Draft International Standard Iso/Dis 19223

DRAFT INTERNATIONAL STANDARD ISO/DIS 19223

ISO/TC 121/SC 4 Secretariat: ANSI Voting begins on: Voting terminates on: 2016-03-18 2016-06-18

Lung ventilators and related equipment — Vocabulary and semantics

Ventilateurs pulmonaires et équipement associé — Vocabulaire et sémantique

ICS: 01.040.11; 11.040.10

THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH. To expedite distribution, this document is circulated as received from the IN ADDITION TO THEIR EVALUATION AS committee secretariat. ISO Central Secretariat work of editing and text BEING ACCEPTABLE FOR INDUSTRIAL, composition will be undertaken at publication stage. TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO WHICH REFERENCE MAY BE MADE IN Reference number NATIONAL REGULATIONS. ISO/DIS 19223:2016(E) RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION. © ISO 2016 ISO/DIS 19223:2016(E)

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form orthe by requester. any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of Ch. de Blandonnet 8 • CP 401 ISOCH-1214 copyright Vernier, office Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47

1 Contents 2 1 * Scope ...... 14

3 2 Conformance ...... 14

4 2.1 General...... 14 5 6 3 Normative references ...... 16

7 4 Terms, definitions, symbols, units and abbreviated terms ...... 16

8 4.1 Breath terminology ...... 18 9 4.1.1 breath ...... 18 10 4.1.2 breathe...... 19 11 4.1.3 spontaneous breath ...... 19 12 4.1.4 natural breathing ...... 19 13 4.1.5 unrestricted breath...... 19 14 4.1.6 respiratory activity ...... 19 15 4.1.7 inspiratory effort...... 20 16 4.1.8 additional breath ...... 20 17 4.1.9 concurrent breath...... 20 18 4.1.10 inspiration...... 20 19 4.1.11 expiration exhalation ...... 20 20 4.1.12 unassisted breath...... 21 21 4.1.13 supported breath ...... 21 22 4.1.14 assisted breath ...... 21 23 4.1.15 synchronised breath...... 21 24 4.1.16 controlled breath ...... 21 25 4.2 Positive-pressure inflation terms and definitions...... 22 26 4.2.1 inflation positive-pressure inflation ventilator inspiration ...... 22 27 4.2.2 inflation-type ...... 22 28 4.2.3 volume-control VC ...... 23 29 4.2.4 pressure-control PC ...... 23 30 4.2.5 dual-control ...... 23 31 4.2.6 pressure-support PS ...... 23 32 4.2.7 proportional effort support pES ...... 24 33 4.2.8 spontaneous/timed pressure-control S/T ...... 25 34 4.2.9 flow-regulation...... 25 35 4.2.10 pressure-regulation ...... 25 36 4.2.11 rise time...... 25 37 4.2.12 primary-inflation ...... 25 38 4.2.13 additional primary-inflation...... 26 39 4.2.14 assured delivery ...... 26 40 4.2.15 support-inflation ...... 26 41 4.2.16 volume targeted vt...... 26 42 4.3 Time, phase and cycle terminology ...... 27 43 4.3.1 expiratory time tE ...... 27 44 4.3.2 expiratory phase ...... 27 45 4.3.3 BAP phase ...... 28 46 4.3.4 BAP time tB ...... 28 47 4.3.5 expiratory-flow time...... 29 48 4.3.6 expiratory pause ...... 29 49 4.3.7 expiratory-pause time ...... 29 50 4.3.8 expiratory hold ...... 29 51 4.3.9 expiratory-hold time ...... 29

52 4.3.10 inspiratory time tI ...... 30 53 4.3.11 inspiratory phase ...... 30 54 4.3.12 inspiratory-flow time ...... 30 55 4.3.13 inspiratory pause ...... 30 56 4.3.14 inspiratory-pause time...... 30 57 4.3.15 inspiratory hold ...... 31 58 4.3.16 inspiratory-hold time...... 31 59 4.3.17 inflation phase...... 31 60 4.3.18 respiratory cycle cycle ...... 31 61 4.3.19 respiratory cycle time cycle time...... 32 62 4.3.20 primary-inflation cycle...... 32 63 4.3.21 phase time ratio I:E ratio ...... 32 64 4.3.22 inspiratory time fraction tI:tTOT ratio ...... 32 65 4.4 Rate terminology...... 32 66 4.4.1 Principle rate concepts - for general use in preference to those listed under 67 4.4.2, secondary rate concepts ...... 32 68 4.4.1.1 rate Rate ...... 32 69 4.4.1.2 total respiratory rate total rate RR ...... 33 70 4.4.1.3 spontaneous respiratory rate spontaneous rate RRspont ISO spontaneous- 71 breath rate...... 33 72 4.4.1.4 ventilator-initiated inflation rate ventilator-initiated rate RRvent ...... 34 73 4.4.2 Secondary rate concepts – rate terms for use if required for specific purposes...... 34 74 4.4.2.1 primary-inflation rate...... 34 75 4.4.2.2 support-inflation rate ...... 34 76 4.4.2.3 assisted breath rate ...... 34 77 4.4.2.4 synchronised breath rate ...... 35 78 4.4.2.5 controlled breath rate...... 35 79 4.4.2.6 unassisted breath rate ...... 35 80 4.4.2.7 additional breath rate...... 35 81 4.4.2.8 patient-triggered primary-inflation rate ...... 35 82 4.4.2.9 concurrent supported-breath rate...... 36 83 4.4.2.10 concurrent unassisted-breath rate ...... 36 84 4.4.2.11 non-concurrent unassisted-breath rate...... 36 85 4.4.2.12 patient-triggered inflation rate ...... 36 86 4.4.2.13 total inflation rate ...... 36 87 4.4.2.14 additional primary-inflation rate ...... 36 88 4.5 Pressure Terminology ...... 37 89 4.5.1 airway pressure PAW ...... 37 90 4.5.2 inspiratory pressure...... 37 91 4.5.3 peak inspiratory pressure ...... 38 92 4.5.4 plateau inspiratory pressure plateau pressure ...... 38 93 4.5.5 inspiratory-pressure relief ...... 38 94 4.5.6 Δ delta...... 38 95 4.5.7 Δ inspiratory pressure Δ pressure Δp ...... 39 96 4.5.8 end-inspiratory pressure ...... 39 97 4.5.9 expiratory pressure ...... 39 98 4.5.10 expiratory pressure-relief ...... 40 99 4.6 Flow terminology ...... 40 100 4.6.1 inspiratory flow Flow ...... 40 101 4.6.2 peak inspiratory flow ...... 41 102 4.6.3 inspiratory-termination flow ...... 41 103 4.6.4 end-inspiratory flow...... 41 104 4.6.5 expiratory flow...... 41 105 4.6.6 expiratory-termination flow...... 42 106 4.6.7 end-expiratory flow ...... 42

107 4.6.8 bias flow ...... 42 108 4.6.9 continuous flow...... 42 109 4.6.10 descending ramp flow pattern ...... 43 110 4.6.11 concave decreasing-flow pattern...... 43 111 4.6.12 demand flow ...... 43 112 4.6.13 airway leak...... 44 113 4.6.14 ventilator breathing system leak VBS leak ...... 44 114 4.7 Volume terminology ...... 44 115 4.7.1 tidal volume VT ...... 44 116 4.7.2 delivered volume VD EL...... 45 117 4.7.3 inspiratory volume VI ...... 45 118 4.7.4 expired tidal volume VTE ...... 46 119 4.7.5 leakage tidal volume VTLeak ...... 46 120 4.7.6 minute volume VM ...... 46 121 4.7.7 delivered minute volume VMDEL ...... 47 122 4.7.8 inspiratory minute ventilation VMI ...... 47 123 4.7.9 expired minute volume VME ...... 47 124 4.7.10 leakage minute volume VMLeak ...... 47 125 4.7.11 assured minute volume VMassd...... 48 126 4.7.12 additional minute volume VMaddn ...... 48 127 4.8 Mode Terminology ...... 48 128 4.8.1 ventilator mode ...... 48 129 4.8.2 ventilation mode ...... 48 130 4.8.3 ventilation-pattern ...... 49 131 4.8.4 *ventilation-mode groups ...... 50 132 4.8.4.1 ventilation-mode Group 1 ...... 50 133 4.8.4.1.1 Group 1a ...... 50 134 4.8.4.1.2 Group 1b ...... 50 135 4.8.4.2 ventilation-mode Group 2 ...... 51 136 4.8.4.2.1 Group 2a ...... 51 137 4.8.4.2.2 Group 2b ...... 51 138 4.8.4.3 ventilation-mode Group 3 ...... 51 139 4.8.4.3.1 Group 3a ...... 51 140 4.8.4.3.2 Group 3b ...... 51 141 4.8.5 *assured ventilation mandatory ventilation...... 52 142 4.8.6 CMV continuous mandatory ventilation ...... 52 143 4.8.7 Assist/Control Ventilation A/CV ...... 53 144 4.8.8 IMV intermittent mandatory ventilation ...... 53 145 4.8.9 SIMV synchronised intermittent mandatory ventilation...... 54 146 4.8.10 CSV continuous spontaneous ventilation SPONT ...... 54 147 4.8.11 MMV minimum minute volume ...... 55 148 4.8.12 * APRV airway pressure release ventilation APRV ...... 55 149 4.8.13 CPAP continuous positive airway pressure ...... 56 150 4.8.14 apnoea ventilation apnea ventilation...... 57 151 4.8.15 back-up ventilation ...... 57 152 4.8.16 systematic ventilation-mode name...... 57 153 4.8.17 alternative mode name alternative ventilation-mode name ...... 57 154 4.8.18 superordinate mode ...... 58 155 4.8.19 breathing therapy mode ...... 58 156 4.9 Mode Adjunct and Bi-level Terminology ...... 58 157 4.9.1 adjunct ventilation-mode adjunct ...... 58 158 4.9.2 ACAP assured constant airway pressure...... 58 159 4.9.3 ACAPL ACAP-low assured constant airway pressure, low...... 59 160 4.9.4 ACAPH ACAP-high assured constant airway pressure, high ...... 60 161 4.9.5 bi-level ventilation bi-level...... 61

162 4.9.6 bi-level positive airway pressure bi-level PAP BPAP ...... 61 163 4.9.7 BAP pressure-low pL ...... 61 164 4.9.8 pressure-low phase pL phase...... 62 165 4.9.9 time-low tL ...... 62 166 4.9.10 BAP-high pressure-high pH ...... 62 167 4.9.11 BAP-high phase pressure-high phase pH phase ...... 63 168 4.9.12 time-high tH ...... 63 169 4.10 Initiation and termination terminology ...... 63 170 4.10.1 initiate ...... 63 171 4.10.2 trigger...... 64 172 4.10.3 flow trigger...... 64 173 4.10.4 pressure trigger ...... 64 174 4.10.5 trigger level...... 64 175 4.10.6 patient-trigger event trigger-event ...... 65 176 4.10.7 breath synchronization ...... 65 177 4.10.8 synchronisation window ...... 65 178 4.10.9 mandatory ...... 65 179 4.10.10 auto trigger...... 66 180 4.10.11 breath stacking ...... 66 181 4.10.12 ventilator-initiation ...... 66 182 4.10.13 remote inflation-initiation ...... 66 183 4.10.14 termination ...... 66 184 4.10.15 flow-termination ...... 66 185 4.10.16 pressure-termination ...... 67 186 4.10.17 time-termination ...... 67 187 4.11 Baseline and PEEP terminology ...... 67 188 4.11.1 BAP baseline airway-pressure baseline pressure PEEP ...... 67 189 4.11.2 PEEP positive end-expiratory pressure ...... 68 190 4.11.3 expiratory-control algorithm ...... 69 191 4.11.4 total PEEP tPEEP ...... 70 192 4.11.5 dynamic PEEP dPEEP...... 71 193 4.11.6 delta PEEP ΔPEEP...... 71 194 4.12 Safety limits and alarm terminology ...... 71 195 4.12.1 Safety limits ...... 71 196 4.12.1.1 pressure limit airway-pressure limit ...... 71 197 4.12.1.2 pressure-limited pLim ...... 72 198 4.12.1.3 maximum limited pressure maximum limited airway-pressure ...... 72 199 4.12.1.4 maximum deliverable airway-pressure ...... 72 200 4.12.1.5 high-airway-pressure limit ...... 72 201 4.12.1.6 high-pressure relief limit high-airway-pressure relief limit...... 73 202 4.12.1.7 high-pressure termination limit high-airway-pressure termination limit ...... 73 203 4.12.1.8 maximum settable inspiratory pressure...... 74 204 4.12.1.9 adjustable pressure limit adjustable airway pressure limit APL ...... 74 205 4.12.2 Alarm conditions ...... 74 206 4.12.2.1 alarm condition ...... 74 207 4.12.2.2 high-pressure alarm condition high-airway-pressure alarm condition ...... 74 208 4.12.2.3 continuing pressure alarm condition continuing airway-pressure alarm 209 condition ...... 75 210 4.12.2.4 low inspiratory-pressure alarm condition ...... 75 211 4.12.2.5 low PEEP alarm condition ...... 75 212 4.12.3 Alarm limits ...... 75 213 4.12.3.1 alarm limit ...... 75 214 4.12.3.2 high-airway-pressure alarm limit ...... 75 215 4.12.3.3 low inspiratory-pressure alarm limit ...... 76 216 4.13 General artificial ventilation terminology...... 76

217 4.13.1 ventilator lung ventilator ...... 76 218 4.13.2 airway...... 76 219 4.13.3 airway device ...... 76 220 4.13.4 airway resistance ...... 76 221 4.13.5 lung compliance...... 77 222 4.13.6 ventilation ...... 77 223 4.13.7 artificial ventilation ...... 77 224 4.13.8 automatic ventilation ...... 77 225 4.13.9 mechanical ventilation ...... 77 226 4.13.10 positive-pressure ventilation ...... 77 227 4.13.11 negative-pressure ventilation NPV ...... 78 228 4.13.12 non-invasive ventilation NIV...... 78 229 4.13.13 tube compensation TC...... 78 230 4.13.14 lung ...... 79 231 4.13.15 lungs ...... 79 232 4.13.16 respiratory system...... 79 233 4.13.17 respiratory system coefficients ...... 79 234 4.13.18 ventilator breathing system VBS anaesthesia breathing system ...... 79 235 4.13.19 set ...... 80 236 4.13.20 measured...... 80 237 4.13.21 preset value...... 81 238 4.13.22 actual value ...... 81 239 4.13.23 limit...... 81 240 4.13.24 normal use ...... 81 241 4.13.25 intended use intended purpose ...... 82 242 4.13.26 normal condition ...... 82 243 4.13.27 single fault condition ...... 82 244 4.13.28 accompanying document ...... 82 245 4.14 Gas Port Terminology ...... 82 246 4.14.1 port ...... 82 247 4.14.2 gas intake port...... 82 248 4.14.3 emergency air intake port ...... 83 249 4.14.4 exhaust port...... 83 250 4.14.5 gas output port ...... 83 251 4.14.6 gas return port ...... 83 252 4.14.7 gas input port ...... 83 253 4.14.8 patient-connection port patient connection...... 83 254 255 Annex A (Informative) Rationale and Guidance ...... 85

256 A.1 General guidance...... 85 257 A.2 Rationale for particular clauses and sub-clauses...... 85 258 259 Annex B (Informative) not used ...... 90

260 Annex C Illustrations of Ventilation Terms (Informative) ...... 91

261 Figure C.1 —Format used in this International Standard for representations of 262 ventilation patterns and inflation-types ...... 92 263 Figure C.2 (1 of 5) — Illustrations of the application of defined ventilation terms in 264 designating key features of typical inflation waveforms ...... 93 265 Figure C.2 (2 of 5) —Illustrations of the application of ventilation terms in 266 designating key features of typical inflation waveforms ...... 94

267 Figure C.2 (3 of 5) — Illustrations of the application of ventilation terms in 268 designating key features of typical inflation waveforms ...... 95 269 Figure C.2 (4 of 5) —Illustrations of the application of ventilation terms in 270 designating key features of typical inflation waveforms ...... 96 271 Figure C.2 (5 of 5) — Illustrations of the application of ventilation terms in 272 designating key features of typical inflation waveforms ...... 97 273 Figure C.3 — Typical airway pressure and flow waveforms for a CMV-PC mode ...... 98 274 Figure C.4 — Typical airway pressure and flow waveforms for a CMV-VC 275 mode ...... 99 276 Figure C.5 — Typical airway pressure and flow waveforms for a CMV- PC 277 mode set with extended phase times ...... 100 278 Figure C.6 — Typical airway pressure and flow waveforms for a CMV- PC 279 mode set with an extreme inverse I:E ratio ...... 101 280 Figure C.7 — Typical airway pressure and flow waveforms for an A/CV - PC mode ...... 102 281 Figure C.8 — Typical airway pressure and flow waveforms for an A/CV – VC mode ...... 103 282 Figure C.9 — Typical airway pressure and flow waveforms for an A/CV – PC 283 mode ...... 104 284 Figure C.10 — Typical airway pressure and flow waveforms for an SIMV- PC\PS mode ... 105 285 Figure C.11 (1 of 4) — Typical airway pressure and flow waveforms for variations on 286 an SIMV- PC\PS\PS mode ...... 106 287 Figure C.12 — Typical airway pressure and flow waveforms for a CSV - PS mode ...... 110 288 Figure C.13 — Characteristics of a concurrent breath ...... 112 289 Figure C.14 (1 of 6) — Ventilation patterns (a) Key to symbols used in b) to f)...... 113 290 Figure C.14 (2 of 6) — Ventilation patterns (b) CMV ventilation-pattern ...... 114 291 Figure C.14 (3 of 6) — Ventilation patterns c) Assist/Control ventilation-pattern ...... 115 292 Figure C.14 (4 of 6) — Ventilation patterns (d) IMV ventilation-pattern ...... 116 293 Figure C.14 (5 of 6) — Ventilation patterns (e) SIMV ventilation-pattern ...... 117 294 Figure C.14 (6 of 6) — Ventilation patterns (f) CSV ventilation-pattern...... 118 295 296 Annex D Classification of Inflation-types and Modes (Normative) ...... 119

297 D.1 Classification of Inflation-types ...... 119 298 Table D.1a —Inflation-type ...... 123 299 Table D.1b —Coding Scheme for variants of Volume Control inflation-types...... 124 300 Table D.1c — Systematic coding scheme for Inflation-types ...... 125 301 D.2 Classification of Ventilation-modes ...... 127 302 Table D.2 — Systematic classification of typical ventilation-modes, with an ACAP 303 adjunct as a third designation ...... 128 304 305 Annex E Conceptual Relationships between Ventilator Actions and Inspiratory Breaths 306 (Informative) 129

307 Figure E.1 — Diagram showing the concepts of the relationship between breath and 308 inflation related terms in the vocabulary of the International Standard...... 131 309 310 Annex F Concepts Relating to Baseline Airway Pressures and PEEP as Used in this Standard 311 (informative) 132

312 Figure F.1 (1 of 2) — Illustrations of the application of BAP and PEEP terminology...... 134 313 Figure F.1 (2 of 2) — Illustrations of the application of BAP and PEEP terminology...... 135 314 Figure F.2 — The BAP/Expiratory phase ...... 136 315 Figure F.3 (2 of 2) — Illustrations of the function of the expiratory-control algorithm 316 on ventilators with an ACAPL adjunct (or an equivalent function) during BAP 317 phases ...... 138

318 319 Annex G Conventions followed in this International Standard (Informative) ...... 139

320 G.1 Avoidance of repetition ...... 139 321 G.2 Post-coordinated terms ...... 139 322 G.3 Use of hyphens...... 139 323 G.4 Flows and pressures ...... 139 324 G.5 Measurements ...... 140 325 G.6 Multiplicity of terms ...... 140 326 G.7 Use of the terms expiration and exhalation ...... 140 327 G.8 The use of symbols to represent defined terms...... 141 328 G.9 Bi-level terminology ...... 141 329 330 Annex H Terminology — Alphabetized index of defined terms (Normative) ...... 143

331 Annex I Index of figures (Informative)...... 154

332 I.1 Annex E Figures...... 155 333 I.2 Annex F Figures...... 155 334 Bibliography 156

335

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received. www.iso.org/patents

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

This first edition of ISO 19223 was prepared with the cooperation of ISO TC 121/SC3 Lung ventilators and related equipment, , IHE Patient Care Devices, Rosetta Terminology Mapping Ventilators, International Healthcare Terminology Standards Development Organization: Anaesthesia Special Interest Group, HL7 Anesthesia Special Interest Group.

This is the first edition of ISO 19223.

In this standard, the following print types are used:

 Definitions: roman type.

 Material appearing outside of tables, such as notes, examples and references: in smaller type.

 Terms defined in clause 4 of this standard or as noted: italic type

In this standard, the conjunctive “or” is used as an “inclusive or” so a statement is true if any combination of the conditions is true.

The verbal forms used in this standard conform to usage described in Annex H of the ISO/IEC Directives, Part 2. For the purposes of this standard, the auxiliary verb:

 “shall” means that compliance with a requirement or a test is mandatory for compliance with this standard;

 “should” means that compliance with a requirement or a test is recommended but is not mandatory for compliance with this standard;

 “may” is used to describe a permissible way to achieve compliance with a requirement or test.

An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title indicates that there is guidance or rationale related to that item in Annex A.

Introduction

The ventilation modes of current automatic lung ventilators are not well understood by many healthcare providers. The currently used terminology used for their description is based on that introduced in the early days of mechanical ventilation but with the advances in ventilators, and the modes of ventilation, that have evolved over recent years, the language used had to be continuously adapted. In the absence of any international coordinating action this had inevitably led to increasing inconsistencies in the way in which well-established terms and their derivatives are used.

To further compound the difficulties in understanding this complex area, ventilator manufacturers have created new proprietary terms to describe some of these new ways to ventilate patients, and some have used existing terms that have different definitions in different situations. This has led to patient safety hazards as, for example, clinical ventilator orders for one model of ventilator may be quite different to that required get the same result from a different ventilator.

Recognizing these difficulties, ISO Technical Committee (TC) 121 Subcommittee (SC) 4 was requested to completely review the terminology and semantics for patient ventilation with a view to creating an International Standard to suit current and, as far as possible, future practice. The intention was, first, to use as much existing terminology as possible while clarifying its meaning as well as putting a limit on its misuse by defining it more precisely. Secondly, to introduce new terms only where there was no alternative; either in order to name new concepts or where the misuse of existing vocabulary has become so widespread that the term has become meaningless or ambiguous. Emphasis was to be placed on creating a terminology that would communicate a clear mental model of the selected ventilator/patient interaction to the operator/user and designers of health information technology systems.

In order to harmonize the terms over several applications for patient care, research and incident reporting, this International Standard has been developed with the cooperation and assistance of other standards development organizations, as detailed in the Foreword, and of major international ventilator manufacturers. The applications include lung ventilation equipment, medical data systems facilitating clinical care and research, interoperability incident reporting and equipment maintenance.

In their review before producing this standardised vocabulary, the subcommittee found that it was necessary to revert to first principles; an approach that included consideration of automatic ventilation from a systems perspective. In the early use of automatic ventilation the patient was ventilated with little regard for the patient’s own respiratory activity and much of the current terminology has its origins in that practice. Modern ventilators interact with the patient as a ‘ventilator-patient system’ resulting in interactions are non-deterministic. This means that one cannot, with any certainty, predict ahead of time how a patient will interact with a ventilator. It is often no longer possible for an operator to set a ventilator and foresee the exact form of the resultant pressure and flow waveforms unless the patient is anesthetized and given a neuromuscular blocking drug.

The terminology in this vocabulary must, therefore, be defined and used in a way that makes it capable of facilitating, unambiguously, both the setting of a ventilator and then describe and record the result of the ventilator-patient interaction, after the event has occurred, at defined points within the course of ventilation. This includes the result of the complex interactions within simultaneous respiratory cycles as may occur, for example, during APRV (airway pressure release ventilation).

This International Standard seeks to provide both a consensus view and to lead to a coherent language for describing ventilator function. Now that ventilation practice has matured it has been possible to review the boundaries between the various established ventilation modes and methods of artificially inflating a patient’s lungs and to formulate descriptions that clarify the common elements and the distinctions. Terms that were relevant to earlier technology and practice but are not adaptable to current practice have been deprecated or discarded and the application of many other terms has been constrained to more specific definitions. The objective is to encourage a more disciplined use of ventilator terminology so that operators trained in the standardised language will be able to move easily from one ventilator to another and operate each one, with confidence, after a minimum of training. Although change will not be immediate it is expected that this discipline will feed through into articles, textbooks and training so that over time a standard basic language of artificial ventilation will become internationally established.

Examples of application of this vocabulary are illustrated in the Figures of Annexes C and F but these are not intended to indicate a requirement nor to impose any restriction on the design of ventilation devices.

The semantics of defined terms, along with their classification schemes, are explained, both in notes to individual entries into this vocabulary and in associated Annexes.

Many of the terms in this vocabulary are intended for the technical explanation on how the various inflation-types, breaths, and ventilation-modes function and may be found to be needed only within technical descriptions.

Lung Ventilators and related equipment—Vocabulary and Semantics

1 * Scope This International Standard establishes a vocabulary of terms and semantics for all fields of respiratory care such as intensive-care ventilation, anaesthesia ventilation, home-care ventilation including sleep apnoea breathing therapy equipment and emergency and transport ventilation. It may be used:

 in lung ventilator and breathing therapy device standards

 in health informatics standards

 for labelling on medical electrical equipment and medical electrical systems

 in medical electrical equipment and medical electrical systems instructions for use and accompanying documents

 for medical electrical equipment and medical electrical systems interoperability

 in electronic health records

This International Standard may also be used for those accessories intended by their manufacturer to be connected to a ventilator breathing system, or to a ventilator, where the characteristics of those accessories can affect the basic safety or essential performance of the ventilator and ventilator breathing systems.

NOTE The vocabulary may also be used for other applications involving lung ventilation including research, description of critical events, forensic analysis and adverse event (vigilance) reporting systems.

This International Standard does not specify terms specific to high-frequency ventilation or negative-pressure ventilation, or to respiratory support using liquid ventilation, extra-corporeal gas exchange, or use of gas mixtures not primarily composed of nitrogen and oxygen.

Many terms entered into this clause of this International Standard originated in ISO 4135. On publication of this International Standard, this vocabulary will supersede the equivalent vocabulary in ISO 4135. It is intended that ISO 4135 will then be appropriately revised, restricting its scope to only deal with terms outside the scope of this International Standard.

2 Conformance

2.1 General

In order to claim conformance with the vocabulary of this International Standard, in this first edition the minimum requirement is that, wherever relevant, any terms used for the labelling of a ventilator and in its accompanying documents that do not conform to its vocabulary are listed alongside the equivalent standardised term in a dedicated section of the product information that is readily accessible to the operator. In particular, all ventilation modes that may be selected on the conforming ventilator are required to be listed using the coded form of the systematic name as specified in this International Standard alongside the labelled name used on the ventilation

14 © ISO 2016 – All rights reserved ISO/DIS 19223:2016(E) device or equipment. These listings should be accompanied by brief descriptions of the basic modes available on the ventilator, using the vocabulary of this International Standard.

Although there are no further requirements in order to conform to this first edition of this International Standard, it is the intention that the present requirements will be extended as further editions are published. In preparation for such changes it is expected that this vocabulary will be adopted by authors, and in teaching and training, so that users will become familiar with its usage before it is widely implemented in the marking and Instructions for Use of ventilators. The following informative guidelines are provided to indicate how the vocabulary of this International Standard is intended to be used.

This International Standard is intended to contribute to the effectiveness and safety of the practice of artificial ventilation by providing a coherent vocabulary covering. It has been structured so that it is sufficiently adaptable to facilitate the description of novel deviations but is recognized that some future innovations may require the use of terms and concepts not covered by this edition of this vocabulary.

The terms, names and acronyms listed in this Standard have been described in a manner that formalizes their interpretation to the extent that it minimizes ambiguity and provides a rigid usage discipline for formal data handling and informatics, whilst retaining phraseology that is suitable for user instructions and clinical dialog.

In the application of the vocabulary of this International Standard, the full term should always be used wherever any ambiguity must be avoided and where there is no trade-off with conciseness, for example, in the formulation of data bases. However, in many applications the context of use may make some of the parts of a compound preferred term redundant, in which case abbreviations, symbols and permitted terms may be used, as appropriate.

In the particular case of terms representing set, actual or measured values, qualifications such as ‘set’ or ‘measured’ may be omitted where the meaning is obvious from the context of use.

Where space is particularly limited such as on a typical user interface, or conciseness is necessary, it is permissible to use abbreviations or symbols to represent a preferred term, providing the context makes it self-evident as to whether it relates to a set, actual or measured value and that the instructions for use relate the abbreviation or symbol to the preferred term. As examples, in a section on a user interface designated for ‘settings’ the input key for inspiratory flow may be marked simply as ‘Flow’ and that for inspiratory time an appropriate symbol such as ‘tI’. However, where abbreviations and symbols are used in this way their meaning and the associated full term are to be provided in the instructions for use. Symbols are not within the scope of this International Standard and have only been included as alternative preferred or admitted terms where there appears to be an existing general consensus relating to their use in representing the main terms used when setting a ventilator. Their inclusion is only for guidance and their format and use is not a normative requirement. For further information and recommendations refer to Annex G.8. Even with these considerations, the exclusive use of the terms listed in this International Standard may still be too formal for some applications and the intention is that in conformance with future editions of this International Standard manufacturers will still be able to still retain their

a) The standardised term should be used in preference to any other where it is applicable.

b) The standardised terms may be used in a variety of post co-ordinations and with any alternative grammatical forms provided that the meaning conveyed is in accordance with the definitions of the terms and concepts in this International Standard.

c) Where proprietary and trade names and acronyms for modes and control algorithms are used they shall be explained in terms of the concepts defined in this International Standard in an appropriate section of, or supplement to, the instructions for use and, as a minimum requirement after major upgrades or on new models, on a help screen on the ventilator.

d) The meaning conveyed by any proprietary term, where applicable, should be the same as that described in this International Standard for the same concept or combination of concepts.

e) Text prepared by the manufacturer and others to explain and describe artificial ventilation may use their own phraseology in expressing the concepts involved but the underlying concepts defined in this International Standard is to be adhered to.

f) Descriptions of artificial ventilation practice not directly covered by the vocabulary of this International Standard may use appropriate new terms where necessary but it is required that these terms are described in respect of the concepts described in this International Standard wherever possible.

g) Terms conforming with this International Standard under the permitted exceptions b) to f) are required to be chosen and used in a manner that avoids any conflicts that could cause confusion to those trained in the vocabulary in this International Standard.

3 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

Not used

NOTE 1 Informative references are listed in the bibliography on page 156.

4 Terms, definitions, symbols, units and abbreviated terms

NOTE For convenience, an index and list of sources of all defined terms used in this document are given in Annex H.

4.0 General

Many terms in the vocabulary of this International Standard originated in ISO 4135. On publication of this International Standard its vocabulary will supersede the equivalent vocabulary

in ISO 4135. It is intended that ISO 4135 will then be appropriately revised, restricting its scope to only deal with terms outside the scope of this International Standard.

4.0.1 Guidance followed in the writing of this International Standard

Vocabulary and terminology standards are required by ISO to be prepared taking into account the guidance of ISO 704, Terminology work - Principles and methods, ISO 10241- 1, Terminological entries in standards - Part 1: General requirements and examples of presentation, and the ISO/IEC Directives, Part 2, 2011 -- Rules for the structure and drafting of International Standards.

The following concepts extracted from ISO 704 were considered to be of particular relevance to the formatting of the vocabulary in this International Standard:

Standardized terminologies should reflect a coherent terminological system that corresponds to the concept system of the subject field in question. The terminology defined in an International Standard should be precise and lead to increased clarity in communication.

A primary function of a standardised terminology is to indicate preferred, admitted, and deprecated terms. A term recommended by a technical committee shall be considered a preferred term whereas an admitted term shall represent an acceptable synonym for a preferred term. Deprecated terms are terms that have been rejected. Terms are rejected or deprecated for a number of reasons. A term may be a synonym for the preferred term but is deprecated in the interests of monosemy (having a single meaning). Alternatively a term may be flawed, inaccurate or may be used with a different definition.

[SOURCE: ISO 704]

4.0.2 Explanation of the principles adopted in the preparation of the vocabulary entries in this clause

As stated in the preceding extracts, a primary function of a standardised terminology is to indicate preferred, admitted, and deprecated terms. In subject fields where there is no standardised terminology, such as is the case with respect to artificial ventilation, it is inevitable that there is often more than one term in common use for the designation of a given concept. However, in choosing a preferred term in this vocabulary it was recognised that in the vocabulary of ventilation a compromise often has to be made between the conflicting requirements for the avoidance of ambiguity and the need for conciseness. In this vocabulary the preferred term has been chosen as the one that is most generally used; with admitted terms (synonyms), abbreviations and symbols sometimes also listed for use where appropriate, depending on the context of use. Where a term is listed as ‘deprecated’, this means that it is deprecated as a synonym for the preferred term, although some such terms are used as preferred terms for the designation of other concepts.

In accordance with the ISO 10241-1:2011 Clause 6.4.4, the definitions of terms entered into this clause are intensional definitions. Such definitions are required to consist of a single phrase specifying the concept being designated, and if possible, to reflect the position of the concept in

the concept system; containing only information that makes the concept unique. A definition given without an indication of its applicability is to be taken as representing the general meaning of the term. Any additional descriptive information deemed necessary is included in notes to entry or in examples. Notes to entry follow different rules from notes integrated into other text; they provide additional information that supplements the terminological data.

Because a ventilator is a device that, typically, interacts with a patient in accordance with inputs from an operator, certain of the concepts of artificial ventilation are of quantities with a value that may be either the actual value or the intended value as set, directly or indirectly, by an operator. In these instances, the definition is used to represent the general meaning of the term. If it is, or may be, used to represent either, or both, a set value or an actual value, this is stated in a note to entry. An actual value exists as a concept whether it can be measured or not and is, therefore, unaffected by the accuracy of measurement or the method by which it may be displayed or recorded. For this reason, the vocabulary of this International Standard only addresses actual values, set values and measured values as concepts. It is for particular standards to specify any requirements regarding measurement accuracy and units of measurement.

The terminological entries hereunder are formatted in accordance with the current ISO rules for the presentation of terminology standards. The vocabulary of this International Standard is primarily arranged in a systematic order, with a secondary alphabetical order. An alphabetical list of terms is provided at the end of this document.

For further information concerning set, actual and measured values, and on how this vocabulary is intended to be applied, particularly with respect to context and qualification, see also Clause 2, Conformance. For further information concerning some of the conventions followed in this clause see informative Annex G.

4.1 Breath terminology

4.1.1 breath increase in the volume of gas in the lung resulting from an inward gas flow through the airway, paired with a corresponding decrease in volume resulting from its expiration

Note 1 to entry: The inward flow may be caused by a positive-pressure inflation, a patient inspiratory effort, or a combination of the two. The outward flow results from a patient’s exhalation.

Note 2 to entry: A breath is composed of two phases: an inspiratory phase (4.3.11), or an inflation phase (4.3.17), and an expiratory phase (4.3.2).

Note 3 to entry: The volume of gas that enters and leaves the lung during a breath may differ due to physical and/or compositional changes between inspired and exhaled gas, and leakages at the connection to the patient’s airway.. Temporarily, it may also differ, breath-to-breath, in the event of, for example, dynamic hyper-inflation or specific patient actions.

Note 4 to entry: This definition accommodates the concept of additional breaths occurring within the period of a primary-inflation cycle.

Note 5 to entry: See also lung (4.13.11), inspiratory volume (4.7.3), expired tidal volume (4.7.4), tidal volume (4.7.1) and additional breath (4.1.8).

4.1.2 breathe take gas into the lungs and then expire it

Note 1 to entry: Breathing is a spontaneous human activity that may be detected by a ventilator but in this vocabulary is never considered to be a ventilator function.

Note 2 to entry: This term is typically used to designate this action as a continuously repeated physiological process but may be used to designate the taking of a single breath or even an inspiration or expiration.

4.1.3 spontaneous breath breath initiated by the patient

Note 1 to entry: This definition is patient-centric and independent of a ventilator or sleep apnoea breathing-therapy device.

Note 2 to entry: The detection of a spontaneous breath by a medical device depends on the set detection threshold of a relevant physiological parameter(s), which may include a parameter(s) that relate to the patient’s intention to breathe and not the actual movement of gas.

Note 3 to entry: The qualifier ‘spontaneous’ makes it clear that such breaths occur as a result of the patient's, generally subconscious, physiological processes, and consequently have elements of unpredictability in initiation, size and duration.

Note 4 to entry: From an artificial ventilation perspective a spontaneous breath is also one to which the patient has contributed at least a proportion of the work of inspiration. More specific terms, which provide an indication of relative magnitude, are subsets of the general term and range from ‘breathing effort’ and ‘breathing activity’ to ‘natural breath’. These are all parts or types of spontaneous breaths, as are spontaneous inspiration and spontaneous expiration.

Note 5 to entry: See also breath (4.1.1).

4.1.4 natural breathing breathing with a workload within the range that a patient might expect to experience when not requiring artificial ventilation and not connected to a ventilator

Note 1 to entry: See also breathe (4.1.2), unassisted breath (4.1.12) and unrestricted breathing (4.1.5).

4.1.5 unrestricted breath unassisted breath with a workload within the range that a patient might expect to experience during natural breathing

Note 1 to entry: See also unassisted breath (4.1.12) and natural breathing (4.1.4).

4.1.6 respiratory activity activity of the patient's respiratory system related to the desire to breathe

Note 1 to entry: This term typically serves as a reference to the minimum detectable form of the physiological indications of the patient’s respiratory intentions, which may be used to improve the interaction between the ventilator and the patient. The term also serves as the reference to the level of effort to be supported during proportional effort support inflations.

Note 2 to entry: This term may be expressed as the activity during either of the phases of a breath, i.e., a patient inspiratory activity or a patient expiratory activity.

Note 3 to entry: Respiratory activity may be detected as a patient generated change in flow or pressure of gas in the airway, respiratory muscle activity, respiratory control-centre activity or other neural signals.

4.1.7 inspiratory effort effort by the patient's respiratory muscles that contributes to the work of inspiration or that generates detectable changes sufficient to cause a patient-trigger event

Note 1 to entry: This definition is patient-centric and independent of the ventilator or sleep apnoea therapy equipment.

Note 2 to entry: See also breathe (4.1.2).

4.1.8 additional breath one of any breaths per minute that are additional to the ventilator set rate in modes where a rate is set

Note 1 to entry: The additional breath rate is the total respiratory rate minus the set rate.

Note 2 to entry: With assist/control ventilation (A/CV) modes it is sometimes not possible to identify any one breath as an additional breath; it is only possible to deduce the number of additional breaths per minute by comparing the total respiratory rate with the set rate as explained in note 1 to entry.

Note 3 to entry: All separate inspirations that occur concurrently with or between primary-inflations are counted as additional breaths, whether unassisted or supported. Patient-trigger events that initiate a primary-inflation are only counted as additional breaths if they initiate additional primary-inflations. See also additional primary-inflation (4.2.13).

Note 4 to entry: The concept of additional breaths facilitates the identification of additional-breath rate (4.4.2.7) and additional minute volume (see 4.7.12).

4.1.9 concurrent breath additional breath, or phase of a breath, initiated during an inflation phase

Note 1 to entry: Inspiratory phases of the breath may be unassisted, or supported.

Note 2 to entry: This is a separate breath, or phase of a breath, following a change of airway flow direction or zero airway flow, while the lung is still inflated. Complete concurrent breaths are only possible with the provision of ACAP or ACAPH.

Note 3 to entry: It is only the detection of the inspiratory phase of a concurrent breath that contributes to the total respiratory rate but the volume change of either concurrent phase is included in the respective minute volume. (See spontaneous-breath rate (4.4.1.3)).

EXAMPLE: See Figures C.5, C.6, C.11a - d, and C.13 (Annex C).

4.1.10 inspiration DEPRECATED AS SYNONYM: inhalation DEPRECATED AS SYNONYM: inhale process of gas entering the lungs through the patient’s airway

4.1.11 expiration exhalation process of gas leaving the lungs through the patient’s airway

Note 1 to entry: The admitted term, in its various grammatical forms, may be used instead of expiration in reference to a patient action, wherever the use of certain grammatical forms of expiration may seem inappropriate in the presence of patients. This admitted use is considered to be generally not necessary for impersonal purposes such as in medical databases and computer records.

Note 2 to entry: This definition recognises that expiration, during both natural breathing and artificial ventilation, is a process that typically extends beyond the time during which gas is actually flowing out from the lungs and only terminates when inspiratory flow next starts.

4.1.12 unassisted breath spontaneous breath by a patient connected to a ventilator, with no assistance from an inflation

Note 1 to entry: An increase of airway pressure applied during the inspiratory phase of a spontaneous breath, with the declared intended use of compensating for any work of breathing imposed by an airway device or the functioning of the ventilator, is not classed as an inflation in this vocabulary. (See also tube compensation (4.13.13)).

Note 2 to entry: The patient’s work of breathing when taking a spontaneous breath may be reduced by the provision of ACAP or CPAP, but because no assistance is provided, such a breath is unassisted. (See also ACAP (4.9.2)).

Note 3 to entry: Unless demand flow is provided by the ventilation mode selected, or by an ACAP adjunct, an unassisted inspiration may require an unsustainable inspiratory effort.

4.1.13 supported breath spontaneous breath with assistance from a pressure support or proportional effort support inflation-type

Note 1 to entry: See also pressure support (4.2.6) and proportional effort support (4.2.7).

4.1.14 assisted breath spontaneous breath with assistance from a patient-triggered primary-inflation at a rate in excess of that set

Note 1 to entry: An assisted breath is assisted by a primary-inflation of the selected type but only occurs if initiated before the next assured delivery is due to occur, at an interval determined by the set rate. Each assisted breath, therefore, occurs at a rate higher than that set; a rate which is solely determined by the patient.

Note 2 to entry: A spontaneous breath that is supported by a pressure support or proportional effort support inflation-type, or by a primary-inflation within a synchronisation window, although also assisted, is separately identified by the specific characteristic that distinguishes it from an assisted breath, namely, supported breath or synchronised breath, respectively.

Note 3 to entry: See also supported breath (4.1.13) and synchronised breath (4.1.15).

4.1.15 synchronised breath spontaneous breath with assistance from a primary-inflation, initiated by a patient-trigger event within a synchronisation window

Note 1 to entry: Synchronised breaths are assured to occur at the set rate.

Note 2 to entry: See also synchronisation window (4.10.8) and assisted breath (4.1.14).

4.1.16 controlled breath breath associated with a ventilator-initiated primary-inflation

Note 1 to entry: A controlled breath is always initiated by the ventilator and subsequently, in the absence of any ensuing spontaneous breathing activity by the patient, generated entirely by the inflation waveform set or selected by the operator. Controlled breaths, therefore, are assured to occur at the set rate.

Note 2 to entry: See also set rate (4.4.1.1)

4.2 Positive-pressure inflation terms and definitions

4.2.1 inflation positive-pressure inflation ventilator inspiration ventilator action intended to increase the volume of gas in the lung by the application of an elevated-pressure waveform to the patient-connection port until a specified termination criterion is met

Note 1 to entry: An elevation of the airway pressure, above the end-expiratory pressure of the previous phase, generates, in the absence of total airway obstruction, an inspiratory flow that will either assist or totally control the inflation of the patient's lungs.

Note 2 to entry: If the inflation is pressure-regulated and the inspiratory phase is set to extend beyond the inspiratory-flow time then the lungs are held distended until the inflation is terminated. During this inspiratory pause, concurrent breathing may be possible, to the extent determined by the specific ventilation mode selected and whether an ACAP adjunct is provided.

Note 3 to entry: Although, typically, there will be more than one inflation-termination criterion, for patient safety reasons, these will always include time-termination, intended as either a primary or secondary means.

Note 4 to entry: If an inflation is terminable by means additional to time, this vocabulary requires that this is indicated, at least in the instructions for use, in accordance with the inflation-type systematic naming and coding tables, D.1a, D.1b and D.1c (Annex D).

Note 5 to entry: The elevated pressure waveform is implemented by either a flow-regulation function or a pressure- regulation function.

Note 6 to entry: This is a context-sensitive term designating an intermittent elevated-pressure ventilator parameter, as distinct from a negative-pressure ventilator inflation or a lung inflation resulting solely from a patient’s inspiratory effort. When used in its defined context the preferred term is used by itself but in cases of possible ambiguity the qualified form, ‘positive-pressure inflation’, should be used.

Note 7 to entry: The admitted term ventilator inspiration is included to facilitate translation into languages that do not have a translation for the word inflation as it is used in this context.

4.2.2 inflation-type property-class named, type of inflation characterised by its temporal delivery pattern following initiation, and its termination criteria

Note 1 to entry: Inflation-types are designated in this vocabulary by their property-class common names, wherever possible. They are more precisely designated by a systematic coding scheme, which uses the abbreviations of the common names, where available, but which also often includes designators of additional properties and designates inflation-types with no common name as yet attributed to them.

Note 2 to entry: A group of Inflation-types that might be selected for a specific purpose are sometimes given a purpose-class name but such a name is not an alternative name for that inflation-type. As an example, one of a selection of inflation-types may be selected to serve as the primary-inflation within a mode but the inflation-type selected becomes the primary ‘inflation-type’, not an inflation of a ‘primary type’.

Note 3 to entry: For further normative information on inflation-type designations see Types of Inflations and Modes (Annex D).

4.2.3 volume-control VC property-class named inflation-type that generates inspiratory flow to a selected flow-waveform, for a set time, or until the set volume has been delivered

Note 1 to entry: The selected inspiratory-flow waveform is typically that of a constant flow at a set value or of a declining-ramp flow pattern, sometimes after a set rise time. This is maintained for the duration of the inflation phase by means of a flow-regulation function.

Note 2 to entry: The flow-regulation function may either maintain a constant set flow rate or make inflation-to- inflation adjustments to ensure that the set volume is delivered in the set time, particularly when compensating for ventilator breathing system characteristics or airway leakage.

Note 3 to entry: See also Figure C.2 (Annex C) and Classification of Types of Inflations and Modes (Annex D)).

4.2.4 pressure-control PC property-class named inflation-type that acts to generate a constant inspiratory pressure at a set level, following a set pressure rise time

Note 1 to entry: During and after the set rise time the set inspiratory pressure is maintained by means of a pressure- regulation function.

Note 2 to entry: If the patient makes a spontaneous inspiratory effort during a pressure-control inflation this will result in a corresponding increase in inspiratory flow, although not necessarily an increased delivered volume.

Note 3 to entry: If the patient makes a spontaneous expiratory effort during a pressure-control inflation the inspiratory pressure will rise above that set, which may cause immediate termination of the inflation. See also high pressure relief limit (4.12.1.6) and high-pressure termination limit (4.12.1.7).

Note 4 to entry: See also Figure C.2 (Annex C), Classification of Types of Inflations and Modes (Annex D).

4.2.5 dual-control type of inflation in which the regulated variable changes from pressure to flow, or vice versa, during an inflation phase in accordance with the inflation algorithm

Note 1 to entry: A dual-control designation is incomplete without reference to the names of the inflation-types that most closely represent the initial and secondary functions within the dual-control inflation. For examples see Tables D.1a and D.1c (Annex D).

Note 2 to entry: Pressure limitations, as may be achieved by a relief system or flow limitations and, as a consequence, where the set delivered volume may not be achieved, are not considered to be components of a dual-control inflation- type.

Note 3 to entry: See also Tables D.1a and D.1c, and D.1, Ref #17 (Annex D).

4.2.6 pressure-support PS property-class named inflation-type that acts to generate a constant airway pressure, following a set pressure rise time, and is intended to be terminated in response to a patient respiratory

© ISO 2016 – All rights reserved 23 ISO/DIS 19223:2016(E) activity. It is only made available for selection with ventilation modes where it cannot be initiated other than in response to a patient-trigger event

Note 1 to entry: During and after the set rise time the set inspiratory pressure is maintained by means of a pressure- regulation function.

Note 2 to entry: Pressure-support inflation-types are so named because they are specified and configured to be used only to provide assistance to spontaneous breathing.

Note 3 to entry: Pressure support inflations are typically flow-terminated but may be terminated by other means.

Note 4 to entry: It is possible for flow-termination to be actioned by the passive characteristics of the patient's respiratory system alone, without any patient respiratory activity, in which case it is misleading to refer to the inflation as having been patient-terminated. Because current ventilators cannot make this distinction, in this vocabulary flow- terminated inflation-types are not referred to as being patient-terminated.

Note 5 to entry: As noted under, inflation, pressure-support (PS) inflations are time-terminated if not terminated within the set inspiratory time; a setting that may be pre-set or operator adjustable.

Note 6 to entry: By convention, set inspiratory pressures for pressure-support (PS) inflations are usually set relative to their related baseline airway-pressure but all relative pressures are required in accordance with this International e 4.5.6).

Standard to be identified as such by the use of the differential symbol, Δ (se Note 7 to entry: For Group 2 modes with an ACAP or ACAPH adjunct, a single pressure-support inflation setting may be arranged to support breaths throughout the full primary-inflation cycle if its set inspiratory-pressure level is higher than the set inspiratory pressure for the primary-inflation. Alternatively, there may be a second level of pressure- support, relative to the set inspiratory pressure for the primary-inflation, for the assistance of concurrent breaths.

Note 8 to entry: A pressure-control (PC) inflation that is flow-terminated is not classified as pressure support (PS) if used in modes where it may be initiated mandatorily; it is then classified as either a spontaneous/timed pressure- control (S/T) inflation or a pressure-control, flow-terminated (PC(q)) inflation.

Note 9 to entry: See also assured ventilation (4.8.5), flow-termination (4.10.15), ACAP (4.9.2) and Figure C.2 (Annex C).

4.2.7 proportional effort support pES property-class name of an inflation-type that generates an airway-pressure waveform that is intended to be proportional to a patient’s effort as indicated by the measured respiratory activity parameters Note 1 to entry: The intention of this inflation-type is to off-load increased work of breathing due to worsened respiratory system coefficients and thereby to get closer to natural breathing.

Note 2 to entry: The respiratory activity is typically detected as the airway resistance or lung stiffness components of the patient’s inspiratory effort or as neural signals.

Note 3 to entry: The required airway-pressure waveform is typically calculated moment-by-moment by a ventilator algorithm, using the instantaneous measurement of inspiratory flow or electromyography signals; it is put into effect by means of a pressure-regulation function.

Note 4 to entry: If the proportional effort support (pES) inflation is based on measurement of inspiratory flow, the support is most commonly determined by the sum of the independently set proportions of the resistive and/or stiffness components of the patient's inspiratory effort, and the inflation is typically terminated when the inflation flow has declined to a set inspiratory-termination flow threshold.

Note 5 to entry: As noted under pressure-control (PC) inflation, proportional effort support (pES) inflations are time- terminated if not terminated by other means within the set inspiratory time; a setting that may be pre-set or operator adjustable.

Note 6 to entry: See also Table D.1a, Table D.1c and D.1, Refs # 12 - 14 (Annex D).

4.2.8 spontaneous/timed pressure-control S/T property-class named inflation-type that acts to generate a characteristic airway-pressure waveform for a set time if ventilator initiated and terminated by a means responsive to a patient respiratory activity if initiated by a patient-trigger event

4.2.9 flow-regulation function of the ventilator that varies the airway pressure as necessary with time to generate an intended inspiratory-flow waveform irrespective of changes to the respiratory system coefficients or of respiratory activity

Note 1 to entry: See also pressure-regulation (4.2.10).

4.2.10 pressure-regulation function of the ventilator that regulates the airway pressure as necessary with time to generate an intended airway-pressure waveform irrespective of changes to the respiratory system coefficients or of concurrent unassisted inspirations

Note 1 to entry: See also concurrent breath (4.1.9), unassisted breath (4.1.12) and flow-regulation (4.2.9).

4.2.11 rise time indication of the time for the regulated parameter to rise to a set value following the initiation of an inflation

Note 1 to entry: The rise time is often expressed as the slope of a ramp or as the time-constant of the rise although neither of these terms depicts the actual typical trajectory of this pressure rise precisely.

Note 2 to entry: For pressure-regulation this is the time to reach a set inspiratory pressure, for flow-regulation it is the time to reach a set inspiratory flow.

Note 3 to entry: see also Figure C.2 (Annex C).

4.2.12 primary-inflation purpose-class named inflation-type that has been selected for assured delivery at the set rate

Note 1 to entry: In this vocabulary, inflations are classified either by their purpose or by their properties in terms of their characteristic waveform. This term is a purpose-classification, as distinct from the name of an inflation-type, which is a property-classification. See inflation-type (4.2.2).

Note 2 to entry: Primary-inflations may be initiated either by the ventilator or by a patient-trigger event.

Note 3 to entry: All assured deliveries are of primary-inflations but not all primary-inflation deliveries are assured.

Note 4 to entry: With some modes the primary-inflations may be delivered at a greater rate than that set, in response to patient-trigger events. See also additional primary-inflation (4.2.13).

Note 5 to entry: Primary-inflations are typically terminated by the ventilator.

Note 6 to entry: The breath associated with a primary-inflation is ‘assisted’, ‘synchronised’ or ‘controlled’.

Note 7 to entry: This qualified term is used in this vocabulary in reference to ventilation with additional breaths, particularly when these are assisted by another inflation-type(s).

Note 8 to entry: An inflation-type that has been selected for assured delivery may also be initiated by a patient-trigger event, for example, in Assist/control ventilation (A/CV) modes and in SIMV modes.

Note 9 to entry: See also respiratory cycle (4.3.18) for derivation of the post-coordinated term primary-inflation cycle.

Note 10 to entry: See also support-inflation (4.2.15) and C.10, C.11a, C.11b and C.11d (Annex C).

4.2.13 additional primary-inflation primary-inflation initiated by an additional breath

Note 1 to entry: In Group 1b) modes any patient-trigger event will cause the primary-inflation rate to exceed that set. Any primary-inflations per minute in excess of those assured to occur by the set rate (4.4.1.1) become additional primary-inflations. These may be recorded and displayed as the additional-breath rate (4.4.2.7) and give rise to additional minute volume (4.7.12).

Note 2 to entry: See also ventilation-mode Group 1b (4.8.4.1.2), patient-trigger event (4.10.6) and assist/control ventilation (4.8.7).

4.2.14 assured delivery delivery of a selected inflation-type at the set rate

Note 1 to entry: The inflation-type selected for assured delivery is designated as a primary-inflation.

Note 2 to entry: The operator has the assurance that the selected inflation type will be delivered at either on average the set rate, or at least the set rate, depending upon the selected ventilation-pattern.

Note 3 to entry: Assured is used in this vocabulary as the preferred synonym to the legacy term, mandatory. It conveys the concept which mandatory is used to elicit in this vocabulary but avoids the ambiguities which that term engenders. For the reasons explained in the rationale to 4.8, mandatory is only used in this vocabulary when explaining the meaning of legacy ventilation-patterns that incorporate this term.

Note 4 to entry: See also Figures C.7, C.8 and E.1, set rate (4.4.1.1), ventilation-pattern (4.8.3) and mandatory (4.10.9)

4.2.15 support-inflation purpose-class named inflation-type that is intended to be terminated in response to the patient’s respiratory activity and is used in modes where it can only be initiated in response to a patient- trigger event

Note 1 to entry: Support-inflations are so named because they are specified and configured to be used only to provide assistance to spontaneous breathing.

Note 2 to entry: It is not generally possible to designate support-inflations as ‘patient-terminated’ because, typically, they may be also terminated by the patient’s passive lung in the absence of respiratory activity.

Note 3 to entry: The breath associated with a support-inflation is ‘supported’. See supported breath (4.1.13).

4.2.16 volume targeted vt automatic inflation-to-inflation adjustment of the set inspiratory pressure, for inflations in which the delivery is pressure-regulated, with the target of achieving a set delivered volume for each breath

Note 1 to entry: The term ‘target’ is used because the inevitable inflation-to-inflation delay, possible respiratory activity and other limitations in the adjustment result in less precise control or each delivered volume than is achieved

by direct feedback (for example, as is used for the pressure-regulation function) although the average delivered volume will typically converge towards the set value.

Note 2 to entry: This term is applicable to all inflations in which the delivery is pressure-regulated to a set value, including those classified as pressure support (PS) but not to those that respond to patient parameters according to an alternative algorithm, for example, pES. The systematic code becomes, for example, vtPC, vtPS. Such a code becomes the generic classification for established proprietary terms such as ‘Autoflow’, ‘PRVC’, ‘Volume Support’, ‘Volume Guarantee’ and ‘VC+’.

Note 3 to entry: See also Table D.1a, Table D.1b and D.1, Refs # 2 and 3 (Annex D).

4.3 Time, phase and cycle terminology

4.3.1 expiratory time tE duration of an expiratory phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20) .

Note 2 to entry: The symbol, tE, in various fonts, is typically used to designate the expiratory time setting, particularly where space is limited such as on operator interfaces.

Note 3 to entry: As a set quantity the expiratory time is either the intended actual duration, the intended average duration or the assured maximum duration of the expiratory phase of the primary-inflation, depending on the mode selected.

Note 4 to entry: As a measured quantity the expiratory time is that of the longest respiratory cycle unless otherwise specified.

Note 5 to entry: On many ventilators the expiratory time is typically set indirectly, for example, by means of a set rate and inspiratory time.

Note 6 to entry: With expiratory phases alternatively labelled as BAP phases, expiratory time becomes BAP time. In modes labelled as bi-level ventilation, the expiratory time may be identified by the term BAP time or time-low. Further details are given in 4.9.

Note 7 to entry: For information on the use of symbols in the labelling of ventilation equipment see Clause 2 – Conformance and Annex G.5.

Note 8 to entry: See also primary-inflation (4.2.12), respiratory cycle (4.3.18), Figures C.3, C.4, C.7 and C.8 (Annex C) and Figure F.2 (Annex F).

[SOURCE: ISO 4135: 2001, 3.4.6]

4.3.2 expiratory phase interval from the start of expiratory flow to the start of inspiratory flow within a respiratory cycle

Note 1 to entry: If additional spontaneous breaths are possible their expiratory phase may occur within the expiratory phase of a primary-inflation cycle.

Note 2 to entry: In accordance with the conceptual framework of this vocabulary, the phase between inflations in any respiratory cycle is the expiratory phase of that cycle. For ventilators where there may be concurrent respiratory cycles it may not be clear as to which of the cycles is being referenced unless it is specifically associated with the primary-inflation cycle each time it is used. In order to avoid that possible ambiguity with concision, the alternative name, BAP phase, has been introduced for use on ventilators that facilitate additional breaths in the phase between primary inflations.

Note 3 to entry: See also BAP phase 4.3.3, additional breath (4.1.8), respiratory cycle (4.3.18), primary-inflation cycle (4.3.19), primary-inflation (4.2.12) and Annex C.

[SOURCE: ISO 4135: 2001, 3.4.5, modified]

4.3.3 BAP phase alternative name for the phase between primary-inflations, in particular on ventilators where unassisted or supported spontaneous inspirations are facilitated during that phase in at least one of the selectable modes on that ventilator

Note 1 to entry: Although this is also the expiratory phase of the primary-inflation cycle, unless that association is made clear each time it is used, if there are additional respiratory cycles there is ambiguity as to which expiratory phase is being referred to. The use of the term BAP phase is therefore much more concise. This is particularly relevant with SIMV and bi-level ventilation modes that may use extended BAP phases of up to 30 seconds or more.

Note 2 to entry: This phase is designated as the BAP phase because, although the conceptual baseline at this set level is continuous, it is only required as a continuous reference following termination and up till the point of initiation of a primary-inflation phase. If additional breaths concurrent with a primary-inflation are possible, these will be superimposed on a higher baseline, at the inspiratory-pressure level, which may be alternatively labelled as BAP-high.

Note 3 to entry: The reason for labelling all expiratory phases as BAP phases on ventilators with at least one mode where that is applicable, is to ensure consistent labelling on any one device. The term may also be applied to the expiratory phases of other classes of inflation if the resulting consistency is assessed as improving usability.

Note 4 to entry: See also unassisted breath (4.1.12), supported breath (4.1.13), spontaneous breath (4.1.3), additional breath (4.1.8), primary-inflation cycle (4.3.20), respiratory cycle (4.3.18) and BAP-high (4.9.10) bi-level ventilation (4.9.5) and Annex C.

4.3.4 BAP time tB duration of a BAP phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: The symbol, tB, in various fonts, is typically used to designate the BAP time setting, particularly where space is limited such as on operator interfaces.

Note 3 to entry: As a set quantity the BAP time is either the intended actual duration, the intended average duration or the assured maximum duration of the BAP phase of the primary-inflation, depending on the mode selected.

Note 4 to entry: As a measured quantity the BAP time is that of the longest respiratory cycle.

Note 5 to entry: On many ventilators the BAP time is typically set indirectly, for example, by means of a set rate and inspiratory time.

Note 6 to entry: In modes labelled as bi-level ventilation, the BAP time may be alternatively identified by the term time-low. Further details are given in 4.9.

Note 7 to entry: For information on the use of symbols in the labelling of ventilation equipment see Clause 2 – Conformance and Annex G.5.

Note 8 to entry: See also primary-inflation (4.2.12), respiratory cycle (4.3.18), Annex C and Figure F.2 (Annex F).

4.3.5 expiratory-flow time duration of the interval from the start of expiratory flow to its cessation

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20

Note 2 to entry: In practice, it may be difficult to measure the actual flow time precisely because of its slow decline but this term is unlikely to be used in the description of situations where precision is critical.

Note 3 to entry: The expiratory flow time and the expiratory time can be equal.

Note 4 to entry: See also Figures C.2 and C.10 (Annex C).

4.3.6 expiratory pause portion of the expiratory phase from the end of expiratory flow to the start of inspiratory flow

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: See also expiratory hold (4.3.8).

[SOURCE: ISO 4135: 2001, 3.4.3, modified]

4.3.7 expiratory-pause time duration of an expiratory pause

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

[SOURCE: ISO 4135: 2001, 3.4.4]

4.3.8 expiratory hold execution of a ventilator function intended to temporarily maintain a constant lung volume during a set extension of the expiratory phase

Note 1 to entry: The maintenance of a constant lung volume is typically used to either facilitate the measurement of dynamic PEEP or to temporarily immobilise the torso (e.g., for diagnostic imaging).

Note 2 to entry: This function can be achieved by temporarily occluding the airway, by maintaining pressure at the patient-connection port or by other means. For the measurement of dynamic PEEP it is necessary to use an expiratory hold achieved with an occluded airway.

Note 3 to entry: Both the initiation and the duration of the function are settings.

Note 4 to entry: See also expiratory-hold time (4.3.9) and expiratory pause (4.3.6).

4.3.9 expiratory-hold time duration of an expiratory hold

Note 1 to entry: The hold time may be set by selecting a time or determined by the duration of a manual input.

4.3.10 inspiratory time tI duration of an inflation or inspiratory phase

Note 1 to entry: In addition to its direct reference, this term or its symbol, tI, may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20)

Note 2 to entry: The symbol, tI, in various fonts, is typically used to designate the inspiratory time setting, particularly where space is limited such as on operator interfaces.

Note 3 to entry: For information on the use of symbols in the labelling of ventilation equipment see Clause 2 – Conformance and G.5.

[SOURCE: ISO 4135: 2001, 3.4.13, modified]

4.3.11 inspiratory phase interval from the start of inspiratory flow to the start of expiratory flow during an unassisted breath

Note 1 to entry: If additional spontaneous breaths are possible their inspiratory phase may occur within the inflation phase of a primary-inflation cycle.

Note 1 to entry: See also Figure C.12 (Annex C)

[SOURCE: ISO 4135:2001, 3.4.12, modified]

4.3.12 inspiratory-flow time duration of the interval from the start of inspiratory flow to its cessation

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: This term becomes relevant as a separate concept with inflations where there is an inspiratory pause. Where there is no inspiratory pause it has the same value as the inspiratory time.

Note 3 to entry: See also Figure C.12 (Annex C)

4.3.13 inspiratory pause interval from the end of inspiratory flow to the start of expiratory flow

Note 1 to entry: There is no inspiratory pause when the inspiratory flow ends with the transition to expiratory flow.

Note 2 to entry: See also Figure C.2c (Annex C)

[SOURCE: ISO 4135: 2001, 3.4.10]

4.3.14 inspiratory-pause time duration of an inspiratory pause

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: See also Figure C.2c (Annex C)

[SOURCE: ISO 4135: 2001, 3.4.11]

4.3.15 inspiratory hold ventilator function intended to temporarily maintain a constant lung volume, or to maintain a constant airway pressure, during a set extension of the end of an inspiratory or inflation phase

Note 1 to entry: This function can be achieved by temporarily occluding the airway, by maintaining pressure at the patient-connection port or by other means.

Note 2 to entry: The maintenance of a constant lung volume is typically used to facilitate a separate clinical procedure, e.g., the measurement of lung parameters or a diagnostic imaging examination.

Note 3 to entry: Both the initiation and the duration of the function are determined by the operator.

Note 4 to entry: See also inspiratory pause (4.3.13)).

4.3.16 inspiratory-hold time duration for an inspiratory hold

Note 1 to entry: The hold time may be determined by an elapsed time setting or by the duration of a manual input.

4.3.17 inflation phase interval from the start of the inspiratory flow at the initiation of an inflation to the start of the expiratory flow resulting from its termination

Note 1 to entry: See also concurrent breath (4.1.9) and Figures C.2 – C.12 (Annex C).

4.3.18 respiratory cycle cycle complete sequence of respiratory events that leads to an increase, followed by a corresponding decrease, of gas volume in the lung regardless of how it is generated

Note 1 to entry: The term respiratory cycle has become a generic term for a complete breath cycle, whether it is assisted or unassisted, spontaneous or assured. Its use addresses a problem that arises because in common usage the word ‘breath’ is often used to refer to either a single phase alone or a complete breath cycle. It is also helpful in the consideration of the occurrence of additional breaths within a primary-inflation cycle. The term ‘respiratory cycle’ is more concise than having to qualify ‘breath’ in a way that removes all ambiguity.

Note 2 to entry: This generic term is not intended for use as a universal substitute for any more specifically applicable terms defined in this vocabulary. Its use should be restricted to the improvement of concision and readability in instances such as those cited in note 1 to entry.

Note 3 to entry: For a primary-inflation, the respiratory cycle starts with its initiation and ends with the initiation of the next primary-inflation. See also primary-inflation cycle (4.3.20).

Note 4 to entry: Additional, separate respiratory cycles can be initiated within a primary-inflation cycle; see also additional breath (4.1.8).

Note 5 to entry: See also breath (4.1.1).

EXAMPLE 1: An unassisted, spontaneous inspiratory phase followed by an expiratory phase.

EXAMPLE 2: The sequence of respiratory events following the initiation of a primary-inflation, through to the subsequent initiation of the following primary-inflation.

EXAMPLE 3: A pressure-support (PS) inflation phase followed by its expiratory phase.

4.3.19 respiratory cycle time cycle time duration of a respiratory cycle

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: The set respiratory cycle time of a primary-inflation (in minutes) is typically determined indirectly by taking the reciprocal of the set rate.

4.3.20 primary-inflation cycle respiratory cycle of a primary-inflation

Note 1 to entry: In modes such as SIMV, supported or unassisted additional breaths may be taken during the expiratory phase of the primary-inflation cycle; also during the inspiratory phase if an ACAP adjunct is provided.

Note 2 to entry: See also Annex C

4.3.21 phase time ratio I:E ratio ratio of the inspiratory time to the expiratory time in a respiratory cycle

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: By mathematical convention, a colon or a slash is used to designate a ratio between two values so the addition of the word ‘ratio’ is not strictly necessary. However, its addition is widely practiced and is considered to add to the readability of descriptive texts and lists.

4.3.22 inspiratory time fraction tI:tTOT ratio ratio of the inspiratory time to the respiratory cycle time

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: This ratio may also be expressed as a fraction or a percentage.

4.4 Rate terminology

4.4.1 Principle rate concepts - for general use in preference to those listed under 4.4.2, secondary rate concepts 4.4.1.1 rate Rate DEPRECATED: f number of primary-inflations that are assured to occur in a specified period of time, expressed as inflations per minute

Note 1 to entry: Following established custom and practice, when used in context and without further qualification, this abbreviation of ‘inflation rate’, and its symbol, Rate, has been adopted in this vocabulary for the designation of this concept as a set quantity (4.13.19).

Note 2 to entry: The operator may select the rate directly or indirectly by means of an algorithm (See example 4).

Note 3 to entry: This setting assures the operator that, in the absence of patient-trigger events, primary-inflations will be delivered at intervals not exceeding, on average, 60/(set rate) seconds. The actual interval between any two successive inflations may differ from the set interval by up to the duration of the synchronisation window with mode- patterns that maintain delivery of primary-inflations at the set rate (e.g., Synchronised intermittent mandatory ventilation (SIMV)).

EXAMPLE 1: With an Assist/control ventilation (A/CV) mode the set rate is the assured minimum ventilator- initiated inflation rate; with any patient-initiated (Assist) inflations the total rate becomes higher. See Figure C.14b (Annex C).

EXAMPLE 2: With an Intermittent Mandatory Ventilation (IMV) mode the set rate is the rate at which the primary-inflations are initiated. See Figure C.14c (Annex C).

EXAMPLE 3: With a Synchronized Intermittent Mandatory Ventilation (SIMV) mode the set rate is the average rate at which the primary inflations are initiated. See Figure C.14d (Annex C).

EXAMPLE 4: With one means of achieving a Minimum minute volume (MMV) mode the mode-control algorithm reduces the effective ventilator set rate as necessary with the objective of maintaining the patient’s minute volume at the set level.

4.4.1.2 total respiratory rate total rate RR number of respiratory cycles initiated in a specified period of time, expressed as respiratory cycles per minute

Note 1 to entry: In addition to its direct reference, this term, and its symbol, RR is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The total respiratory rate is the spontaneous respiratory rate plus the ventilator-initiated inflation rate.

Note 3 to entry: Separate respiratory cycles initiated within primary inflation cycles are counted as part of the total

Note 4 to entry: See also additional breath (4.1.8), respiratory cycle (4.3.18) and primary-inflation cycle (4.3.20).

4.4.1.3 spontaneous respiratory rate spontaneous rate RRspont ISO spontaneous-breath rate total number of spontaneous breaths initiated in a specified period of time, expressed as breaths per minute

Note 1 to entry: In addition to its direct reference, this term, and its symbol, RRspont, is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The spontaneous respiratory rate is the difference between the total respiratory rate and the ventilator-initiated inflation rate.

Note 3 to entry: The detection of the beginning and end of a breath is dependent on the sensitivity of the ventilator sensors and the thresholds of the detection algorithms. For further information concerning the reliability of using the patient-triggered rate as a measure of the spontaneous-breath rate see patient-trigger event (4.10.6).

Note 4 to entry: Because there is no dependent action required, as is the case with assisted breaths, the counting of an unassisted spontaneous breath may be delayed until its inspiratory phase has terminated, thereby allowing a higher level of discrimination between actual breaths and spurious events.

Note 5 to entry: Many legacy ventilators display and log the spontaneous breath rate as the unassisted breath rate plus the support breath rate. While true for CSV modes this practice does not include the spontaneous breaths that may initiate primary inflations, for example, in A/CV and SIMV modes, making the spontaneous rate measurement mode dependent. This practice is considered to be misleading and is not supported in this vocabulary. The admitted term ISO spontaneous-breath rate has been included for use where it is necessary to highlight this distinction.

4.4.1.4 ventilator-initiated inflation rate ventilator-initiated rate RRv ent number of inflations initiated by a timed signal within the ventilator in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term, and its symbol, RRv ent, is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: Ventilator-initiated inflations generate controlled breaths. See also controlled breaths (4.1.16).

Note 3 to entry: In this vocabulary an inflation initiated by a patient-trigger event is classed as a patient-triggered inflation; not as a ventilator-initiated inflation. See also primary-inflation (4.2.12).

4.4.2 Secondary rate concepts – rate terms for use if required for specific purposes 4.4.2.1 primary-inflation rate number of primary-inflations initiated in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: In Group 1a) and Group 2 modes the primary inflation rate is assured to be equal to the set inflation rate; in Group 1a) modes the primary inflation rate is assured to be at least equal to the set inflation rate but will be higher if there are additional breaths.

4.4.2.2 support-inflation rate total number of support-inflations initiated in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: See also support-inflation (4.2.15) and supported breath (4.1.13).

4.4.2.3 assisted breath rate number of assisted breaths initiated in a specified period of time, expressed as breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: See also assisted breath (4.1.14).

4.4.2.4 synchronised breath rate number of synchronised breaths initiated in a specified period of time, expressed as units of breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: See also synchronised breath (4.1.15).

4.4.2.5 controlled breath rate number of ventilator-initiated inflations initiated in a specified period of time, expressed as breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: See also controlled breath (4.1.16).

4.4.2.6 unassisted breath rate number of spontaneous breaths with no assistance from an inflation, initiated in a specified period of time, expressed in units of breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: See also unassisted breath (4.1.12).

4.4.2.7 additional breath rate number of additional breaths in a specified period of time, expressed as breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The additional-breath rate is the difference between the total respiratory rate and the set rate.

Note 3 to entry: See also additional breath (4.1.8).

4.4.2.8 patient-triggered primary-inflation rate number of primary inflations initiated by a patient-trigger event in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity ((4.13.20)).

Note 2 to entry: Patient-triggered primary-inflations generate assisted and synchronised breaths. See also assisted breath (4.1.14) and synchronised breath (4.1.15).

Note3 to entry: See also primary-inflation (4.2.12).

4.4.2.9 concurrent supported-breath rate number of support-inflations initiated during primary-inflation phases in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: See also supported breath (4.1.13) and concurrent breath (4.1.9).

4.4.2.10 concurrent unassisted-breath rate number of unassisted spontaneous breaths initiated during primary-inflation phases in a specified period of time, expressed as breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: See also unassisted breath (4.1.12) and concurrent breath (4.1.8).

4.4.2.11 non-concurrent unassisted-breath rate number of unassisted-breaths initiated between primary-inflation phases in a specified period of time, expressed as breaths per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: See also unassisted breath (4.1.12) and concurrent breath (4.1.8).

4.4.2.12 patient-triggered inflation rate number of inflations initiated by a patient-trigger event in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

4.4.2.13 total inflation rate total number of inflations initiated in a specified period of time, however initiated, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The total inflation rate is equal to the primary-inflation rate (4.4.2.1) plus the support-inflation rate (4.4.2.2).

4.4.2.14 additional primary-inflation rate number of additional primary-inflations initiated in a specified period of time, expressed as inflations per minute

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The additional primary-inflation rate is the primary-inflation rate minus the set inflation rate.

Note 3 to entry: See also additional breath (4.1.8) and additional primary-inflation (4.2.13). Pressure terminology

4.5 Pressure Terminology

4.5.1 airway pressure PAW DEPRECATED AS SYNONYMS: See note 6 to entry DEPRECATED AS SYNONYMS: See note to deprecated terms pressure at the patient-connection port, relative to ambient pressure unless otherwise specified

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20)

Note 2 to entry: The site(s) of actual measurement(s) may be anywhere in the ventilator breathing system providing the indicated value is referenced to that at the patient-connection port.

Note 3 to entry: This is the generic term for this fundamental concept. Post-coordinated terms (e.g., peak inspiratory pressure and baseline airway pressure) are used in particular contexts.

Note 4 to entry: Although providing no explicit indication as to where along the patient’s airway this pressure is measured, this term, along with its symbol, has become almost universally adopted as referencing the pressure at the point at which an artificial-ventilation equipment is connected to the patient's airway or to an airway device. This is the final site where a common and replicable pressure can be continuously monitored before breathing gas enters the patient.

Note 5 to deprecated terms: The following terms are deprecated for use as synonyms for airway pressure: patient pressure; proximal pressure; mouth pressure; pressure at the Y-piece; respiratory pressure; working pressure; inflation pressure; delivered pressure; applied pressure; ventilator pressure. Some of these terms may be valid synonyms but, as reiterated in 4.0, one of the objectives of a terminology standard is to nominate just one preferred term to represent a given concept.

4.5.2 inspiratory pressure DEPRECATED: See note 5 to entry airway pressure during an inspiratory or inflation phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity ((4.13.20)).

Note 2 to entry: As a setting, the value of this quantity is the intended constant pressure level to be attained following a set rise time. Inflation-types that are pressure-regulated to a constant level include pressure-control and pressure- support.

Note 2 to entry: As a measurement, this is the general term for the pressure at any point in time during an inspiratory or inflation phase. It will typically be qualified to indicate the point in the phase to which the observation applies, examples being, peak inspiratory pressure, plateau pressure and end-inspiratory pressure. It may also be displayed as a waveform. See alsoG.5 (Annex G).

Note 3 to entry: The inspiratory pressure is always relative to ambient, that is, independent of the baseline airway- pressure

unless indicated otherwise by the differential symbol, Δ, as a prefix. Note 4 to entry: This term is applicable to both primary-inflations and support-inflations.

Note 5 to entry: The following terms are deprecated as synonyms for the term inspiratory pressure: delivered pressure; support pressure; plateau pressure; pressure limit; respiratory pressure; working pressure; target pressure; end-inspiratory pressure; insufflation pressure.

inspiratory pressure (4.5.7)

Note 5 to entry: See also Δ 4.5.3 peak inspiratory pressure maximum inspiratory pressure

Note 1 to entry: Peak inspiratory pressure is always referenced to the ambient pressure.

Note 2 to entry: Unless otherwise indicated, peak pressure is always indicated for the previous primary-inflation cycle.

Note 3 to entry: This International Standard deprecates the use of this term in reference to a setting.

Note 4 to entry: See also Figure C.2 (Annex C).

4.5.4 plateau inspiratory pressure plateau pressure airway pressure after stabilisation to a constant level during an inspiratory-hold with a volume- control inflation-type or during the intended constant-pressure portion of a pressure-regulated inflation

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20). The corresponding set value is that of the inspiratory pressure.

Note 2 to entry: Although the plateau inspiratory pressure during a pressure-regulated inflation is intended to be constant, there will be inevitable minor variations whenever the inspiratory flow is varying, particularly when it changes direction during concurrent breathing. These possible variations should be taken into consideration when measurements of the plateau pressure are required to be made.

Note 3 to entry: Unless the airway pressure reaches its intended constant level during an inflation there will be no plateau pressure and, therefore, no valid measurement can be made.

Note 4 to entry: When given sufficient time at its stabilised level, the plateau pressure will typically be an indication of the end-inspiratory average alveolar pressure.

Note 5 to entry: Although it will often have the same value this term is not a synonym for end-inspiratory pressure.

Note 6 to entry: See also inspiratory pressure (4.5.2), inspiratory hold (4.3.15), inspiratory pause (4.3.13), end- inspiratory pressure (4.5.8) and Figure C.2d (Annex C).

4.5.5 inspiratory-pressure relief means of limiting the maximum inspiratory pressure to the set level by discharging excess inspiratory flow to the atmosphere

Note 1 to entry: The intended maximum inspiratory pressure is determined by the set pressure limit (4.12.1.1).

Note 2 to entry: This form of pressure limitation will often result in the delivered volume falling below that set as the set relief-pressure is approached. Awareness of this characteristic is important for operators of the simple gas- powered ventilators that typically use such pressure-limitation means and in which there is no independent measurement of the actual tidal volume.

4.5.6 Δ delta difference between two quantities

Note 1 to entry: This symbol is used in this vocabulary as a prefix to denote that the qualified parameter is referenced to another parameter. In particular, it is used in this vocabulary to qualify an inspiratory or expiratory pressure to denote when it is referenced to a baseline airway pressure level instead of to the default, ambient pressure level.

Note 2 to entry: In verbal communication, Δ, as used in this vocabulary, is expressed as either ‘delta’ or ‘differential’.

Note 3 to entry: See also Δ inspiratory pressure (4.5.7), and (Annex C).

4.5.7 Δ inspiratory pressure Δ pressure Δp differential airway pressure relative to baseline airway pressure during an inflation phase qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20). Note 1 to entry: In addition to its direct reference, this term or its symbol, Δp, may be used, in context or by Note 2 to entry: There is no agreed convention as to whether an inspiratory pressure must always be expressed as an absolute quantity relative to ambient pressure or an absolute quantity for one group of inflation-types and relative for another. This has unacceptable patient-safety implications that must be addressed in a vocabulary of lung ventilation. requirement in this vocabulary. This means that respiratory pressures are always to be considered to be relative to ambientThe letter pre Δ ssureis sometimes unless prefixedused as a by symbol Δ. In this to make vocabulary, this distinction Δ, when associatedand that convention with a respiratory has been pressure adopted, indicatesas a that that pressure is relative to the set BAP level. In modes where there is a second, higher, baseline airway-pressure, then the indicating symbol h.

for a pressure relative to that higher pressure level becomes Δ Note 3 to entry: The sum of the set baseline airway pressure level and the Δ inspiratory pressure equals the inspiratory pressure. This applies to both settings and measurements of this parameter.

4.5.6) and Figures C.2a and b (Annex C).

Note 4 to entry: See also Δ ( 4.5.8 end-inspiratory pressure airway pressure at the end of an inflation phase

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: This pressure is displayed or recorded as the last measured value of the inspiratory pressure before the initiation of inflation termination.

Note 3 to entry: This pressure may be coincident with the peak inspiratory pressure or the end of an inspiratory pressure plateau and hence have the same value.

Note 4 to entry: The end-inspiratory pressure is always recorded and displayed as an airway pressure, that is, as

relative to ambient pressure, unless indicated otherwise by the differential symbol, Δ, as a prefix. inspiratory pressure (4.5.7) and Figures Figures C.2a and b (Annex2).

Note 5 to entry: See also Δ 4.5.9 expiratory pressure respiratory pressure during an expiratory phase

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: In this vocabulary, an expiratory pressure is taken to be an airway pressure unless used in a compound (post-coordinated) term, in which case the new name or its definition may indicate an alternative measurement reference site or reference pressure level.

Note 3 to entry: As a measurement, this is the general term for the pressure at any point in time during an expiratory phase. It will typically be qualified to indicate the point in the phase or the site to which the observation applies. It may also be displayed as a waveform. See also G.5 (Annex G).

Note 4 to entry: The expiratory pressure is always relative to ambient pressure, that is, independent of the baseline airway-pressure

unless indicated otherwise by the differential symbol, Δ, as a prefix. Note 5 to entry: See also Figures C.2a (Annex 2) and Figures F.1a to c (Annex F).

4.5.10 expiratory pressure-relief function that relieves expiratory pressure by allowing expiratory flow to pass through to the exhaust port with minimal resistance when above the BAP level, but which prevents expiratory flow below that level

Note 1 to entry: Separate valves providing this function (often referred to as PEEP valves) are, typically, standard accessories with bag-valve-mask ventilators.

Note 2 to entry: With this function acting alone during a BAP phase, an unassisted inspiration may incur additional work of breathing, and if there is a leak in the ventilator breathing system or at the connection to the patient, the airway pressure may fall towards the ambient pressure, which will result in a loss of the intended PEEP. Such consequences may be mitigated by the provision of a bias flow or prevented by the provision of demand flow or an ACAP adjunct, active at the BAP level.

4.6 Flow terminology

4.6.1 inspiratory flow Flow DEPRECATED: peak flow flow of gas delivered through the patient-connection port to the patient during an inspiratory or inflation phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: The symbol, Flow, in various fonts, is typically used to designate the inspiratory flow setting, particularly where space is limited such as on operator interfaces.

Note 3 to entry: Where an inflation serves to augment a patient’s spontaneous breath then, conceptually, inspiratory flow can be seen as being comprised of a component of demand flow resulting from the patient’s inspiratory efforts and a component of flow due solely to the raised pressure of the inflation. However, currently, most ventilators cannot separate these two components and so the unattributed inclusive term, inspiratory flow, has been adopted in this vocabulary for general use. The term demand flow is included in this vocabulary for use when there is a necessity to make reference to the flow resulting solely from the patient’s inspiratory efforts as a separate concept.

Note 4 to entry: The set inspiratory flow will be a good representation of the actual flow that generates the tidal volume when it all enters the patient’s respiratory tract. This is frequently not the case due to, for example, leakage at the patient/airway device interface (particularly in neonatal and non-invasive ventilation) and from the operator- detachable part of the ventilator breathing system. With these conditions, a more reliable indication of the actual flow that will enter the respiratory tract will be provided if the inspiratory flow is leak-compensated relative to that set.

Note 5 to entry: For further information on the semantics of measured quantities and the term ‘Flow’ in this vocabulary see sub-clause 4.0, and G.4 and G.5 (Annex G).

Note 6 to entry: See also Figure C.2, inspiratory effort (4.1.7), demand flow (4.6.12), tidal volume (4.7.1), delivered volume (4.7.2) inspiratory volume (4.7.3) and Annex C.

4.6.2 peak inspiratory flow highest flow of gas delivered to the patient through the patient-connection port during an inspiratory or inflation phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a measured value but in this vocabulary is not used to designate this concept as a set value (4.13.19).

Note 2 to entry: See also Figures C.2a and b (Annex C).

4.6.3 inspiratory-termination flow inspiratory flow threshold at which the termination of a flow-terminated inflation-type is initiated

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: This threshold flow is typically expressed as either a set inspiratory-termination flow rate or a set percentage of the peak inspiratory flow rate.

Note 3 to entry: See also inspiratory flow (4.6.1), flow-termination (4.10.15), termination (4.10.14) peak inspiratory flow (4.6.2) and Figure C.2b (Annex C).

4.6.4 end-inspiratory flow flow at the point when inflation termination is initiated

EXAMPLE 1: See Figure C2.

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This flow is that measured before the inspiratory-flow waveform trajectory transitions towards zero in response to a termination signal; the inflation phase itself does not terminate until the airway flow passes through zero.

Note 3 to entry: This flow is that measured before the inspiratory-flow waveform trajectory transitions towards zero in response to a termination signal; the inflation phase itself does not terminate until the airway flow rate passes through zero.

Note 4 to entry: See also termination (4.10.14), inspiratory flow (4.6.1) and inflation phase (4.3.17).

4.6.5 expiratory flow flow from the patient through the patient connection port during an expiratory phase

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20) .

Note 2 to entry: See also Figures C.2a to e (Annex C).

4.6.6 expiratory-termination flow expiratory flow threshold at which the termination of a flow-terminated expiratory phase is initiated

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: A flow-termination means of this type is sometimes used, for example, to minimise the time that the expiratory pressure is at the BAP level in an APRV (airway pressure release ventilation) mode.

Note 3 to entry: This threshold flow is typically expressed as either a set expiratory-termination flow rate or a set percentage of the peak expiratory-flow rate.

4.6.7 end-expiratory flow expiratory flow at the point when an inflation is initiated

EXAMPLE 1: See Figure C2.

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This flow is that measured before the expiratory-flow waveform trajectory transitions towards zero in response to an inflation initiation signal; the expiratory phase itself does not terminate until the airway flow rate passes through zero.

Note 3 to entry: As a measured value, end-expiratory flow is an indication of dynamic PEEP that has not fully dissipated and, therefore, that the pressure in the lungs may be higher than the intended minimum.

4.6.8 bias flow flow that passes through the ventilator breathing system to the exhaust port but is not intended to contribute to the work of lung ventilation

Note 1 to entry: In addition to its direct reference, this term may be used to designate this concept, in context or by qualification, as a set value (4.13.20).

Note 2 to entry: The term bias flow is used to refer to an intended low-level flow that passes right through the ventilator breathing system with the purpose of improving the responsiveness and accuracy of the ventilator’s control and detection systems, and of minimising the rebreathing of expired gas.

4.6.9 continuous flow gas flowing continuously through the ventilator breathing system, with a proportion intermittently passing to the patient’s lung whenever the airway pressure is raised by the ventilator or an operator action, or flow is demanded by a patient’s inspiratory effort

Note 1 to entry: In addition to its direct reference, this term may be used to designate this concept, in context or by qualification, as a set value (4.13.20).

Note 2 to entry: A constant, continuous flow in the inspiratory limb of the ventilator breathing system is commonly used in the artificial ventilation of neonatal and paediatric patients.

Note 3 to entry: The airway pressure may be intermittently raised to a set inspiratory pressure, for example, by timed, pressure-limited occlusions of the expiratory valve.

Note 4 to entry: See also ventilator breathing system (4.13.18) and airway pressure (4.5.1).

4.6.10 descending ramp flow pattern DEPRECATED: decelerating-flow pattern linearly decreasing flow waveform

Note 1 to entry: This term is applicable to the description of a selectable inspiratory flow-waveform pattern.

Note 2 to entry: In most applications the precise linearity of such a waveform is not critical and so this term is appropriate to describe a range of waveforms that includes those that may have minor nonlinearities, providing these are essentially inconsequential.

4.6.11 concave decreasing-flow pattern DEPRECATED: decelerating-flow pattern declining flow waveform, the gradient of which decreases with time

Inspiratory flow

Concave declining-flow pattern EXAMPLE

Time

Note 1 to entry: This term is applicable to the flow-waveform pattern resulting from a pressure-regulated inflation or of a typical expiratory-flow pattern. Although not a common feature, this term is alternatively applicable to the description of a selectable inspiratory flow waveform pattern of this form; a selectable pattern appropriate to simulate a pressure-control (PC) inflation waveform.

Note 2 to entry: A pattern of this form is typical of the airway flow waveform observed in situations where the applied pressure difference across the airway resistance is changing due to the charging or discharging of the compliant lung. Such a pattern is sometimes referred to as an exponential waveform but there is generally too much nonlinearity in the system for that to be even approximately the case.

Note 1 to deprecated term: Although a commonly used term, it is incorrect in that the rate of flow of a gas, which is essentially a measure of its velocity, cannot be ‘decelerated’; it is only a volume of the gas that can be accelerated and decelerated - not the velocity of that gas.

4.6.12 demand flow flow generated by a ventilator solely to meet the flow demand of the patient while acting to maintain the airway pressure at its intended value

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This term denotes the specific subset of inspiratory flow that is solely due to the patient’s spontaneous inspiratory efforts when connected to a ventilator. In certain contexts, a term for this distinction is

helpful but where this is unimportant the concept may be assumed to be included within the scope of the generalised term, inspiratory flow.

Note 3 to entry: During unassisted breathing, the intention is that the demand flow will meet the patient’s flow demands in a manner that provisions for unrestricted breathing at the applicable BAP level. This may involve the use of a function that temporarily elevates the airway pressure slightly, with the intention of compensating for the possible pressure drop across an airway device or for the inevitable pressure drop that is necessary for the pressure- regulation function to provide flow in proportion to the demand. Alternatively, it may be provided by the provision of ACAP, an adjunct that facilitates unrestricted breathing by the generation of demand flow in proportion to the patient’s demand, with no dependency on a patient-trigger event.

Note 4 to entry: Where spontaneous breaths are given assistance by an inflation, the flow through the patient- connection port during the inflation phase will be the sum of that due to the raised pressure of the inflation and that due to the flow demand resulting from the patient’s inspiratory effort. Because there is currently no reliable way to separate these two components, in this vocabulary the total of the flow generated is denoted by the inclusive, general term, inspiratory flow.

Note 5 to entry: See also inspiratory flow (4.6.1).

4.6.13 airway leak loss of respiratory gas from its pathway between the patient connection port connector interface and the lungs

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: Loss of gas at the patient connection port connector interface is part of an airway leak.

Note 3 to entry: An airway leak may be expressed as a flow rate or a volume and during an inspiratory or expiratory phase, or during a period of time.

4.6.14 ventilator breathing system leak VBS leak loss of gas from the ventilator breathing system

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a measured value (4.13.20).

Note 2 to entry: With this definition, this leak does not include any loss of gas at or beyond the interface in the patient connection port connector.

Note 3 to entry: The term may be applied to the total ventilator breathing system leakage or, more specifically, to any leakage that influences the displayed values of delivered volume or expired minute volume. Any such implications should be disclosed by the manufacturer.

Note 4 to entry: International Standards generally require that ventilator breathing system leakage is expressed as a rate of flow at BTPS (body temperature and pressure, saturated).

Note 5 to entry: See also ventilator breathing system (4.13.18), patient connection port (4.14.8), delivered volume (4.7.2) and expired minute volume (4.7.9).

4.7 Volume terminology

4.7.1 tidal volume VT volume of gas that enters and leaves the lung during a breath

Note 1 to entry: In addition to its direct reference, this term or its symbol, VT, may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19). As a measured quantity it is only used to designate this concept when expressed as a compensated value.

Note 2 to entry: In practice, the volumes that enter and leave the lung are typically measured as a delivered volume and an expired tidal volume because, even without leakage, these two quantities will only be nominally equal due to physical and/or compositional changes of the gas and normal physiological variation in end-expiratory lung volume. Leakages between the point at which the flow towards the patient is measured and the lung, such as occur at the connection to the patient’s airway, will increase these discrepancies.

Note 3 to entry: Without leakage compensation the measured expired tidal volume will be a better representation of the actual tidal volume because leakage is less during expiration than during delivery due to the lower mean airway pressure. Where leakage compensation is in operation the actual delivered and inspiratory volumes are typically greater than the set tidal volume but the compensated tidal volume provides a better representation of the actual tidal volume.

Note 4 to entry: With ventilation equipment where no inspiratory or expired volume measurements are available the actual tidal volume may deviate from the set value as a result of the factors referred to in note 2 to this entry.

4.7.2 delivered volume VDEL net volume of gas delivered to the operator-detachable part of the ventilator breathing system during an inflation or inspiratory phase

Note 1 to entry: In addition to its direct reference, this term or its symbol, VDEL, may only be used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The delivered volume is a good representation of the actual tidal volume when all of the delivered volume enters the patient’s respiratory tract. This is frequently not the case due to, for example, leakage at the patient/ventilator interface (particularly in neonatal and non-invasive ventilation). However, where the actual delivered volume is leak compensated relative to that set the setting is considered to be a sufficiently reliable indication of the tidal volume for it to be so labelled.

Note 3 to entry: The delivered volume is defined as a net volume because it is the actual volume delivered minus any volume that passes through the expiratory valve as a consequence of a bias flow.

4.7.3 inspiratory volume VI volume of gas delivered through the patient connection port during an inflation or inspiratory phase

Note 1 to entry: In addition to its direct reference, this term or its symbol, VI, may only be used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This is the concept designated by entry 3.4.2, delivered volume, in ISO 4135:2001; a term that has not been widely adopted to date. It is a concept relevant to measurements of volume made close to the patient connection port, such as is typically the case with self-contained, multi-parameter patient monitors, as distinct from the redefined delivered volume (4.7.2), which is applicable to ventilators where the inspiratory flow is determined or measured within the body of the ventilator. The closer site of measurement means that this quantity only differs from the actual volume entering the lung by the amount of any volume leakage occurring at the connection to the patient’s airway.

Note3 to entry: See also delivered volume (4.7.2) and tidal volume (4.7.1).

4.7.4 expired tidal volume VTE volume of gas leaving the lung through the patient connection port during an expiratory phase

Note 1 to entry: In addition to its direct reference, this term is used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: Where there is concurrent breathing, although the ventilator can determine the inspiratory volume of the additional breaths their expiration may be combined with the primary expiration, which is typically displayed with no separate attributions.

Note 3 to entry: This term would be appropriate to designate this concept, in context or by qualification, as a set (4.13.20) target value for this quantity but this is typically not currently practiced because of other factors that would have to be taken into account.

4.7.5 leakage tidal volume VTLeak volume of gas lost from the measured volume passing to the patient, before it enters the lung, in a single respiratory cycle

Note 1 to entry: In addition to its direct reference, this term is used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This leakage is typically estimated based on a comparison of the measured volume passing to the patient with the measured expired tidal volume, and the mean inspiratory and expiratory pressures.

4.7.6 minute volume VM DEPRECATED: V� volume of gas either passing to or leaving the lung during inspiratory or inflation phases, or expiratory phases, respectively, expressed as a volume per minute

Note 1 to entry: In addition to its direct reference, this term or its symbol, VM, may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19). As a measured quantity it is only used to designate this concept when expressed as a compensated value.

Note 2 to entry: Unless otherwise qualified, this term designates the volume either passing to or leaving the lung during all of the respective inspiratory or inflation phases, or expiratory phases that have occurred during the period of measurement. This term is appropriately qualified when used to denote the minute volumes resulting from specific types of inflations or breaths (for an example see assured minute volume (4.7.11)).

Note 3 to entry: While a minute volume is expressed as a volume per minute, the actual measurement period will typically be that of a specified number of complete respiratory cycles or of a time other than one minute, in order to provide a more consistent average value. The term by itself suggests that its value is that of a volume but experience has indicated that users prefer the assurance of it being expressed as an average flow rate, that is, as a Volume/min.

Note 4 to entry: In practice the volumes that enter and leave the lung per minute are typically measured as a delivered minute volume and an expired minute volume because, even without leakage, these two quantities will only be nominally equal due to physical and/or compositional changes of the gas and normal physiological variations in end-expiratory lung volume. Leakages between the point at which the flow towards the patient is measured and the lung, such as occur at the connection to the patient’s airway, will increase these discrepancies.

Note 5 to entry: Without leakage compensation the measured expired minute volume is expected to be a better representation of the actual minute volume because leakage is less during expiration than during delivery due to the lower mean airway pressure. Where leakage compensation is in operation the actual delivered and inspiratory

minute volumes are typically greater than the set minute volume but the compensated minute volume provides a better representation of the actual minute volume.

Note 6 to entry: With ventilation equipment where no inspiratory or expired volume measurements are available the actual minute volume may deviate from the set value as a result of the factors referred to in note 2 to this entry.

is incorrect

NoteMinute 1 tovolume deprecated is the term:integral The of symbola varying V�� isflow sometimes rate and usedso is asan aaverage designation rate of for flow. minute For volume. correct representationThis this wobecauseuld require V� is a symbolthe addition for the of differential ‘ ¯ ‘ of volume with time, that is, dV/dt, which is an instantaneous flow rate.

above the V�, which presents typological difficulties. 4.7.7 delivered minute volume VMDEL net volume of gas delivered to the operator-detachable part of the ventilator breathing system during all inflation and inspiratory phases, expressed as a volume per minute

Note 1 to entry: Delivered minute volume is also referred to as minute volume when all of the delivered volume enters the patient’s respiratory tract. This is frequently not the case due to, for example, leakage at the patient/ventilator interface (particularly in neonatal and non-invasive ventilation). However, where the displayed minute volume of gas delivered is leak compensated the observation is considered to be a sufficiently reliable indication of the minute volume for it to be so labelled.

4.7.8 inspiratory minute ventilation VMI volume of gas delivered through the patient connection port during all inflation and inspiratory phases, expressed as a volume per minute

Note 1 to entry: In addition to its direct reference, this term or its symbol, VMI, may only be used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This is the concept designated by entry 3.4.1, delivered ventilation, in ISO 4135; a term that has not been widely adopted to date. It is a concept relevant to measurements of volume made close to the patient connection port, such as is typically the case with self-contained, multi-parameter patient monitors, as distinct from the redefined delivered minute volume (4.7.7), which is applicable to ventilators where the inspiratory flow is determined or measured within the body of the ventilator. The closer site of measurement means that this quantity only differs from the actual volume entering the lung per minute by the amount of any leakage minute-volume occurring at the connection to the patient’s airway.

4.7.9 expired minute volume VME DEPRECATED: expired ventilation volume of gas leaving the lung through the patient connection port during all expiratory phases, expressed as a volume per minute

Note 1 to entry: In addition to its direct reference, this term is used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

4.7.10 leakage minute volume VMLeak gas lost from the measured volumes passing to the patient, before they enter the lung, during a specified time or number of respiratory cycles, expressed as a volume per minute

Note 1 to entry: In addition to its direct reference, this term is used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This leakage is typically estimated based on a comparison of the known delivered flows/volume with the measured expiratory flows/volume, and the mean inspiratory and expiratory pressures.

4.7.11 assured minute volume VMassd minute volume due to the ventilation set rate

EXAMPLE 1: The minute volume resulting from all the primary inflations in an SIMV mode.

EXAMPLE 2: The minute volume resulting from the set number of primary inflations in an A/CV mode.

Note 1 to entry: In addition to its direct reference, this term is used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: The assured minute volume is the minute volume resulting only from inflations delivered at intervals determined by the set rate.

Note 3 to entry: In A/CV modes, where the measured primary-inflation rate is in excess of the set rate then the assured minute volume is the set-rate/primary-rate proportion of the expired minute volume resulting from primary-inflations.

Note 4 to entry: Where leakage compensated measurements of this quantity are available these may be used in the place of expired minute volume measurements.

4.7.12 additional minute volume VMaddn minute volume that is additional to the minute volume which is due to the ventilation set rate

EXAMPLE 1: The volume resulting from all unassisted and supported breaths.

EXAMPLE 2: The volume resulting from the number of inflations in excess of the set number per minute in A/CV.

Note 1 to entry: In addition to its direct reference, this term is used, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: This is the minute volume resulting from any unassisted breaths and from inflations delivered in addition to the set rate.

Note 3 to entry: In A/CV modes, the additional minute volume is determined as the additional breath-rate/total primary-inflation rate proportion of the expiratory minute volume resulting from primary-inflations.

Note 4 to entry: Where leakage compensated measurements of this quantity are available these may be used in the place of expired minute volume measurements.

4.8 Mode Terminology

4.8.1 ventilator mode way in which a ventilator is set to operate

EXAMPLES: standby; calibration; non-invasive ventilation (NIV); breathing system check

4.8.2 ventilation mode specified manner in which a ventilator performs its ventilatory function when connected to a patient

Note 1 to entry: Although a large number of ventilation modes have been described since mechanical ventilation was introduced, all can be seen to be comprised of two key features. These are, the method employed to make the necessary contribution to the inflation of the patient’s lungs and the patterns with which these contributions occur, based on elapsed time or relative to any respiratory activity of the patient. Increasingly, these two features have been separately identified, classified and taught, and this practice has been formalised in this vocabulary; the development of which led to the adoption of the terms inflation-type and ventilation-pattern for their separate designation.

More recently, microprocessor controls have led to the construction of adult ventilators with an inbuilt facility for patient to be able to make unrestricted expirations, as well as inspirations, at any time, including during an inflation at a constant pressure level; a feature previously restricted to infant ventilators. This feature is separately identified in this vocabulary as a ventilation adjunct.

Note 2 to entry: In this vocabulary, specific classification schemes have been introduced for ventilation modes, inflation-types, ventilation-patterns and ventilation-mode adjuncts. These serve, not only to facilitate their identification and relationships, but as a basis for systematic naming and coding. For further information see D.2 and Table D.2 (Annex D).

Note 3 to entry: If a ventilation mode is automatically switched between that and an alternative ventilation mode, when specified conditions are fulfilled, whether or not it generates an alarm condition, in this vocabulary this arrangement may be given a superordinate mode name. However, its systematic coding will require both ventilation- modes to be identified by its systematic code and to be linked by arrow symbols, as used to indicate dual-control inflation-types, for example, CSV-PS  CMV-VC. (See Ref # 17, Annex D for dual-control inflation-types).

Note 4 to entry: Some ventilation modes, or specific setting protocols for such a mode, have a particular feature(s) that has been seen to justify an alternative name; a name that places emphasis on that feature. Such names, which may be generic or proprietary, are classified as alternative mode names (4.8.17). Examples of such generic mode names are bi-level ventilation and airway pressure release ventilation (APRV).

Note 5 to entry: Other implementations of ventilation modes have an additional supervisory function that is considered to distinguish it from the underlying pattern-based mode to the extent that it too justifies a separate identity. Such a mode is separately classified as a superordinate mode. Most of such modes have proprietary names but an example of a generic mode of this type is MMV.

Note 6 to entry: Although alternative and superordinate mode names, whether generic or proprietary, are adopted or permitted by this International Standard as indicators of the additional or supervisory feature, they will not provide a complete description of the ventilation mode without reference to the systematic code of the ventilation-mode on which it is based, along with an explanation of the alternative or additional feature.

Note 7 to entry: See also ventilation-pattern (4.8.3), inflation-type (4.2), ventilation-pattern group (Error! Reference source not found.), alternative mode name (4.8.17), superordinate mode (4.8.18) and Table D.2.

4.8.3 ventilation-pattern specified temporal pattern of sequenced interactions between a ventilator and the patient, including which, when and by what selected inflation-types are initiated

Note1 to entry: The ventilation-pattern also determines which inflation-types are appropriate for use with that pattern.

Note 2 to entry: Ventilation patterns are invariably too complex to fully classify using a few simple words. It has therefore become customary to identify them by means of short descriptive names or by easily-remembered associated abbreviations or acronyms although, because of a lack of standardisation, the meanings attached to these identifiers have become very variable. However, in most cases the name has not been restricted to use with a specific inflation-type and is therefore equally suitable to name just the ventilation-pattern. In this vocabulary, well established, non-proprietary mode acronyms, or their names, have been adopted wherever possible as the generic names for the principle ventilation-patterns associated with them.

Note 3 to entry: When a named ventilation-pattern is selected the features specified for that pattern in this vocabulary will be made available for setting and described in the instruction for use. However, it is necessary to recognise that, with some modern ventilators, particularly those with an ACAP adjunct, it is inevitable that some ventilation modes

can be set so as to generate specific pressure or flow waveforms that could also be obtained with specific settings of a ventilation mode with a different ventilation-pattern selected.

Note 4 to entry: The names or codes used to identify ventilation-patterns in this vocabulary are only used as systematic names or codes for modes that conform to the definition provided in this vocabulary. A ventilation-pattern that does not conform in this way should be described in terms of the most similar ventilation-pattern, with an explanation of the differences. .

Note 5 to entry: A specified ventilation-pattern, together with a specified inflation-type(s) and the type of any mode adjunct, constitutes the core, systematic name of any mode used for positive-pressure ventilation.

Note 6 to entry: A ventilation-pattern is independent of the inflation-type(s) selected and of the set values for parameters such as the set rate, inspiratory pressure and phase-time ratio.

Note 7 to entry: See also Table D.2 (Annex D).

4.8.4 *ventilation-mode groups groups of ventilation-modes that share fundamental features with respect to the characteristics of their ventilation-patterns

Note 1 to entry: The characterisation of ventilation modes into groups in the labelling of ventilators is not a requirement in conformity with this International Standard but where such a grouping is used conformance is required.

Note 2 to entry: See also Table D.2 (Annex D).

4.8.4.1 ventilation-mode Group 1 group of ventilation modes sharing ventilation-patterns in which only one inflation-type can be selected at a time, this being assured to be initiated at least at the set rate

4.8.4.1.1 Group 1a subset of Group 1 ventilation modes with no provision for the selected inflation-type to be initiated by a patient-trigger event

EXAMPLE: CMV (continuous mandatory ventilation) mode.

4.8.4.1.2 Group 1b subset of Group 1 ventilation modes in which the selected inflation-type is assured to be delivered at successive intervals determined by the set rate when not initiated within such an interval by a patient-trigger event.

EXAMPLE: assist/control ventilation (A/CV) mode.

Note 1 to entry: The inflation-type selected is also referred to in this vocabulary by its generic, purpose-classification, that is, primary-inflation (see primary-inflation (4.2.12)).

Note 2 to entry: In the absence of patient-trigger events, primary-inflations will be delivered at intervals of 1/ Rate minutes.

Note 3 to entry: Patient-trigger events cause an increase in the total respiratory rate above the set rate.

4.8.4.2 ventilation-mode Group 2 group of ventilation modes sharing ventilation-patterns in which an inflation-type is selected to be initiated at the set rate. Between, these assured deliveries spontaneous breathing is possible, which may be either unassisted or supported by a second selected inflation-type

4.8.4.2.1 Group 2a subset of Group 2 ventilation modes with no provision for the assured-deliveries to be initiated by a patient-trigger event

4.8.4.2.2 Group 2b subset of Group 2 ventilation modes with the initiation of each assured delivery being synchronised with any spontaneous breathing while maintaining the set rate

Note to Group 2b): See also rate (4.4.1.1).

Note 1 to entry: The inflation-type selected for delivery at the set rate is also referred to in this vocabulary by its generic, purpose-classification, that is, primary-inflation (see also primary-inflation (4.2.13)).

Note 2 to entry: The second inflation-type selected is also referred to in this vocabulary by its generic, purpose- classification, that is, support-inflation (see also support-inflation (4.2.16)). This grouping does not preclude the possibility for the second inflation-type to be set to provide zero support in order to facilitate unrestricted breathing between primary-inflations.

Note 3 to entry: On ventilators with an ACAP adjunct any inspirations occurring concurrently with a pressure-control primary inflation-type, may be assisted by either the selected support-inflation or by an additional, third selected inflation-type (which is also referred to as the second support-inflation).

Group 4 to entry: Group 2 ventilation-modes include those based on the well-established ventilation-patterns used in IMV (Intermittent Mandatory Ventilation) and SIMV (Synchronised intermittent mandatory ventilation)modes. The scope of any mode in this group is independent of whether spontaneous breaths are set to be supported or not between the primary-inflations or whether these inflations are assured to be initiated at an unusual set rate, for example, at only once per minute, in order to recruit the patient's lungs.

Note 5 to entry: See also primary-inflation (4.2.12), primary-inflation cycle (4.3.20), ACAP (4.9.2), adjunct (4.9.14.2.12) and support-inflation (4.2.15).

4.8.4.3 ventilation-mode Group 3 group of ventilation modes sharing ventilation-patterns that enable continuous unrestricted breathing or continuous supported breathing, always with a constant baseline airway pressure at the set BAP level

4.8.4.3.1 Group 3a subset of Group 3 ventilation modes with provision to support each inspiratory activity that exceeds a threshold value

4.8.4.3.2 Group 3b subset of Group 3 ventilation modes with no provision to support any inspiratory activity

Note1 to entry: In this group of modes no inflation is assured to be initiated. If apnoea ventilation is provided for instances of apnoea then this is classified in this vocabulary as an automatic change of ventilation-mode. (See Note 3 to 4.8.2).

Note 2 to entry: Group 3 ventilation-modes include those based on the well-established ventilation-patterns used in CSV (Continuous spontaneous ventilation) and CPAP (Continuous Positive Airway pressure) modes.

Note 3 to entry: The support provided in Group 3a ventilation modes may be by means of pressure support (PS) or proportional effort support (pES) inflation-types. With pressure support the threshold value will be a set value, with proportional effort support the threshold will be the minimum value resolvable by the ventilator.

Note 4 to entry: See also unrestricted breathing (4.1.5), supported breath (4.1.13), baseline airway-pressure (4.11.1), pressure support ( 4.2.6 ), proportional effort support 4.2.7), CSV (Continuous Spontaneous Ventilation) (4.8.10) and CPAP (Continuous Positive Airway pressure) (4.8.13).

4.8.5 *assured ventilation mandatory ventilation patient ventilation by primary-inflations delivered at intervals determined by the set rate

Note 1 to entry: The duration of an assured ventilation episode may be that of a single breath or of a sequence of breaths, ending when a non-synchronising patient-trigger event occurs.

Note 2 to entry: The term assured ventilation is used in this vocabulary to better represent the core concept of the classical ventilation modes, CMV (Continuous mandatory ventilation), IMV (Intermittent Mandatory Ventilation) and SIMV (Synchronised intermittent mandatory ventilation). Mandatory ventilation is retained as an admitted term for this concept in order to provide a link between the use of the word mandatory in the mode name and the more relevant interpretation of its meaning in this vocabulary, that is, the assurance provided by its being required to occur. (See also mandatory (4.2.14)).

Note 3 to entry: It is only primary-inflations delivered at the set rate that contribute to assured ventilation. Primary- inflations that are patient-initiated, and that increase the rate above that set, do not contribute to assured ventilation. (See also primary-inflation (4.2.13)).

Note 4 to entry: Although assured ventilation comprises solely primary-inflations, which could therefore be described as assured inflations, not all primary-inflations can be so described.

Note 5 to entry: With some Group (ii) ventilation-modes, e.g., SIMV, the assured inflations are assured to be delivered at the set rate but are also required to be synchronised with any spontaneous breaths. This is achieved by the use of a synchronisation window that is opened at equal intervals. The actual initiation or that inflation is then either patient- triggered within that window or ventilator-initiated as the window is terminated. This ensures that the assured inflations will be delivered at the set rate although there may be small variations in the inflation-to-inflation time as a consequence of the synchronisation.

Note 6 to entry: It is the intent of the committee to deprecate the admitted term mandatory ventilation in future editions of this Standard.

4.8.6 CMV continuous mandatory ventilation DEPRECATED AS SYNONYM: continuous mechanical ventilation DEPRECATED AS SYNONYM: controlled mechanical ventilation DEPRECATED AS SYNONYM: IPPV DEPRECATED AS SYNONYM: CPPV property-class name of a ventilation-pattern in which a selected inflation-type is assured to be delivered at intervals determined by the set rate, with no facility for any inflation to be initiated by a patient-trigger event

Note 1 to entry: The selected inflation-type is classed as the primary-inflation.

Note 2 to entry: The interval determined by the set rate is 1/Rate minutes.

Note 3 to entry: This is the characteristic ventilation-pattern of Group 1a ventilation-modes.

Note 4 to entry: The initialism, CMV, related to this concept is retained because it is well established, although a number of different names have been associated with it. In this vocabulary it is used only for a ventilation-pattern that does not respond to patient-trigger events of any magnitude (that is, its function is the same as Assist/control ventilation (A/CV) with its trigger function off).

Note 5 to entry: On ventilators with an ACAP adjunct it is possible to set this ventilation mode to replicate IMV (Intermittent Mandatory Ventilation). In such a case the manufacturer’s description of the ventilation mode determines its appropriate designation.

Note 6 to entry: See Figure C.14a (Annex C) for a schematic illustration of this pattern.

4.8.7 Assist/Control Ventilation A/CV DEPRECATED: assist control ventilation DEPRECATED: AC property-class name of a ventilation-pattern in which a selected inflation-type is assured to be initiated at intervals determined by the set rate, unless initiated by an earlier patient-trigger event

Note 1 to entry: The selected inflation-type is classed as the primary-inflation.

Note 2 to entry: With this ventilation-pattern any patient-trigger event will cause the primary-inflation rate to exceed that set. Any primary-inflations per minute in excess of those assured to be delivered by the set rate (4.4.1.1) become additional primary-inflations (which give rise to additional minute volume (4.7.12).

Note 3 to entry: With this ventilation-pattern, if one or more inflations are initiated by a patient-trigger event, although all the inflations are still primary-inflations, there are no specific inflations that can be identified as ‘assured’ or ‘additional’. However, the operator is assured that that the set number of primary-inflations will be delivered per minute and that any inflations per minute above that set will be additional primary-inflations.

Note 4 to entry: The interval determined by the ventilator set rate is 1/Rate minutes.

Note 5 to entry: This ventilation-pattern name is descriptive of its function in that every patient-trigger event initiates the generation of an assisted breath whereas a controlled breath is generated if no patient-trigger event occurs within the interval determined by the set rate. See also assured delivery (4.2.14).

Note 6 to entry: This is the characteristic ventilation-pattern of Group 1b ventilation-modes.

Note 7 to entry: See Figure C.14b (Annex C) for a schematic illustration of this pattern.

Note 8 to entry: See also Figures C.7 – C.9 (Annex C).

Note 1 to deprecated terms: The legacy abbreviation A/C became the established written form for this term. Forms of the term without the forward slash have been used more recently but this practice is deprecated because it fails to convey the OR function implied by the written forms of the preferred term.

4.8.8 IMV intermittent mandatory ventilation property-class name of a ventilation-pattern in which a selected inflation-type is always initiated at a constant interval, as determined by the ventilator set rate. Between these assured deliveries, unrestricted breathing is possible or spontaneous inspirations may be supported by a second selected inflation- type

Note 1 to entry: The inflation-type selected for delivery at the set rate is classed as the primary-inflation and the second inflation-type selected is classed as a support-inflation.

Note 2 to entry: On ventilators with an ACAP adjunct any inspirations occurring concurrently with a pressure-control primary inflation-type, may be assisted by either the selected support-inflation or by an additional, third selected inflation-type (which is also referred to as the second support-inflation).

Note 3 to entry: This is the characteristic ventilation pattern of Group 2a ventilation-modes.

Note 4 to entry: The interval determined by the ventilator set rate is 1/Rate minutes.

Note 5 to entry: It is possible to set ventilation-modes conforming to this pattern to replicate modes with a CMV (Continuous mandatory ventilation) ventilation-pattern on ventilators with an ACAP adjunct. In such cases the manufacturer’s description of the ventilation mode determines its appropriate designation.

Note 6 to entry: See Figure C.14c (Annex C) for a schematic illustration of this pattern.

Note 7 to entry: See also ventilation pattern (4.8.3), ventilation-mode groups (4.8.4) and Table D.2, (Annex D).

4.8.9 SIMV synchronised intermittent mandatory ventilation property-class name of a ventilation-pattern in which a selected inflation-type is initiated at the set rate, with each inflation being synchronised with any spontaneous breathing. Between these assured deliveries unrestricted breathing is possible or spontaneous inspirations may be supported by a second selected inflation-type

Note 1 to entry: Synchronisation is achieved by the use of a synchronisation window, which provides time for the assured delivery to be in phase with any preceding spontaneous breath in order to minimise the possibility of breath stacking.

Note 2 to entry: The synchronisation window is configured so that the initiation of each inflation is synchronised with any spontaneous breathing while maintaining the assured average rate of delivery as determined by the set rate.

Note 3 to entry: The inflation-type selected for delivery at the set rate is classed as the primary-inflation and the second inflation-type selected is classed as a support-inflation.

Note 4 to entry: On ventilators with an ACAP adjunct any inspirations occurring concurrently with a pressure-control primary inflation-type, may be assisted by either the selected support-inflation or by an additional, third selected inflation-type (which is also referred to as the second support-inflation).

Note 5 to entry: This is the characteristic ventilation-pattern of Group 2b ventilation-modes.

Note 6 to entry: See Figure C.14d (Annex C) for a schematic illustration of this pattern.

Note 7 to entry: See also ventilation-pattern (4.8.3), unrestricted breathing (4.1.5), assured delivery (4.2.14), rate (4.4.1.1 ), primary-inflation (4.2.12), support-inflation 4.2.15), synchronisation window (4.10.8), ACAP (4.9.2), breath stacking (4.10.11), IMV (Error! Reference source not found.), Figures C.10 and C.11a to d (Annex C) and Table D.2 (Annex D).

4.8.10 CSV continuous spontaneous ventilation SPONT property-class name of a ventilation-pattern that enables continuous, supported breathing with a constant baseline airway pressure

Note 1 to entry: No support-inflation is assured to be delivered.

Note 2 to entry: With pressure support set to ‘zero’ or ‘none’ modes using this ventilation-pattern function in the same manner as the CPAP (Continuous Positive Airway pressure) ventilation-pattern but because pressure-support is available it cannot be designated as CPAP; in this vocabulary a ventilation mode classification is independent of the setting used.

Note 2 to entry: This is the characteristic ventilation-pattern of Group 3a ventilation-modes.

Note 4 to entry: See Figure C.14e (Annex C) for a schematic illustration of this pattern.

Note 5 to entry: See also ventilation-pattern (4.8.5), supported breath (4.1.13), assured delivery (4.2.14), Figure C.12, (Annex C) and Table D.2 (Annex D).

Note to admitted term: Modes using this ventilation-pattern are commonly labelled on operator interfaces with abbreviations of ‘spontaneous’, such as ‘SPONT’, ‘SPN’ and ‘SPON’, used as symbols.

4.8.11 MMV minimum minute volume generic name of an autonomous ventilation mode that provides assurance to the operator that the patient will receive at least the set minimum minute volume in accordance with the selected mode algorithm

EXAMPLE 1: Mode using an SIMV ventilation pattern where the set rate is adjusted by the MMV algorithm to maintain the set minute volume until the lower limit of the setting is reached.

EXAMPLE 2: Mode using an A/C ventilation-pattern with vtS/T type inflations where the set rate and the set target volume are both continually adjusted in relation to each other in accordance with an established equation, in order to maintain the minute volume at its set level wherever possible.

Note 1 to entry: It is possible for the patient to demand minute volumes in excess of the set value.

Note 2 to entry: This is not to be confused with ‘mandatory minute ventilation’, which was the first implementation of a mode that was described by this initialism. That implementation was an adaptation of a ventilator intended for use during anaesthesia in the operating room and did not provide for spontaneous ventilation in excess of the set minute volume. It was not, therefore, suitable in that form for longer term ventilation. Subsequent developments of the concept have eliminated that restriction and led to its replacement by various forms of ‘minimum minute volume’ ventilation.

Note 3 to entry: This is an autonomous ventilation mode because its name does not describe a mode pattern; it is simply a named ventilatory objective. This objective can be implemented with more than one pattern-based mode but in each case necessarily involving the operator transferring the responsibility for the adjustment of certain parameter settings to the mode algorithm. Intrinsic to such algorithms, is the automatic adjustment of certain initial settings over time, according to the spontaneous activity of the patient.

4.8.12 * APRV airway pressure release ventilation APRV alternative name for a specific setting protocol of a bi-level ventilation mode in which the patient is intended to take natural breaths during an extended primary-inflation phase at BAPH and in which the BAP phase is set to terminate as soon as the alveolar pressure has had time to descend to the set BAP level

Note 1 to entry: APRV is an alternative name for a specific setting protocol for modes such as IMV-PC or IMV- PC[S] ; setting that give extreme inverse phase-time ratios (tH:tL) such that the patient takes unrestricted breaths at a relatively high BAP and but is artificially ventilated by short intermittent pressure releases.

Note 2 to entry: Ventilators supporting this mode may offer the extreme phase-time ratios required either as a suitable time setting or as the result of an algorithm, for example, based on the time for the expiratory flow to reduce

by a set amount or to a set level. With these extreme phase-time ratios available, it is possible to achieve the intended function of airway pressure release ventilation (APRV) by making specific settings on any of a range of bi-level modes, of which IMV-PC is an example.

Note 3 to entry: The terminology used in this definition is that which is appropriate for the labelling of a bi-level mode to be set to an APRV protocol.

Note 4 to entry: See also Figures C.6 and C.11b and c (Annex C).

4.8.13 CPAP continuous positive airway pressure ventilation mode in which the patient breathes continuously at a set baseline airway pressure level (BAP), above ambient

Note 1 to entry: CPAP is intended to maintain the airway pressure at its set value with the exception of the inevitable minor deviations that are necessary for it to perform its function. Although there are currently no tests for acceptable levels for such deviations, they are expected to neither add to nor subtract from the patient’s perceived work of breathing to a greater extent than may be experienced during natural breathing.

Note 2 to entry: This definition excludes the use of the term to describe ventilation modes where spontaneous inspirations are supported by intermittently elevated pressures other than with the intention to compensate for any actual or perceived imposed work of breathing.

Note 3 to entry: Because, as used for this ventilation mode, the concept of a CPAP level coincides with that of a baseline airway pressure the setting could be designated as for either concept but as the intention of the operator selecting this ventilation mode will be to achieve a specific CPAP level this becomes the preferred term to designate the set quantity.

Note 4 to entry: Although at the periphery of what constitutes a ventilation-mode, CPAP is included in this vocabulary because it may be used as part of a continuum of a patient’s treatment without the necessity to change to another device.

Note 5 to entry: It is possible for a CPAP ventilation mode to be realised on a ventilator by the use of CSV (Continuous spontaneous ventilation) with the pressure-support (PS) set to ‘zero’ or ‘none’ but, for the reasons stated in note 1 to entry, CPAP is not equivalent to CSV.

Note 6 to entry: On ventilators with ACAP, this adjunct will enable unrestricted breathing whenever CPAP is selected. CPAP may also be implemented on a ventilator by employing the ventilator’s CSV algorithms but with the pressure- support preset to its ‘zero’ or ‘none’ settings.

Note 7 to entry: CPAP is a Group 3b ventilation-mode. Because no inflation-type is selected this ventilation-mode is identical to its ventilation-pattern and there is no necessity to distinguish between them. The systematic mode code is, therefore, simply, CPAP. On ventilators where CPAP is enabled by means of an ACAP adjunct the systematic code becomes CPAP .

Note 8 to entry: When used for sleep-apnoea breathing therapy CPAP is not classed as a ventilation mode; it becomes a sleep-apnoea breathing therapy mode. Although the principle clinical intention of such a therapy mode is to maintain a positive pressure in the patient’s airway during sleep in order prevent airway obstruction by the soft tissues in the throat it has become a common practice to reduce this pressure during expiration to improve patient comfort. Modes with this feature are typically identified with names that allude to this use of two levels of positive airway pressure. The generic name adopted for the designation of such a breathing therapy mode in this vocabulary is Bi-level PAP.

Note 9 to entry: See also unrestricted breath (4.1.5), baseline airway-pressure (4.11.1), pressure support (4.2.6), breathing therapy mode (4.8.19), CSV (Continuous spontaneous ventilation) (4.8.10), ACAP (4.9.2), CSV (4.8.10) and bi- level PAP (Error! Reference source not found.).

4.8.14 apnoea ventilation apnea ventilation safety provision by which the ventilator automatically switches to a predetermined ventilation mode that generates controlled breaths whenever a hypoventilation alarm condition occurs

Note 1 to entry: A second preferred term for this concept is included in this vocabulary because each form of the key base word, apnoea, is universally used in specific spheres of influence; both within and outside of the scope of this vocabulary.

Note 2 to entry: See also controlled breaths (4.1.16), alarm condition (4.12.2.1) and backup ventilation (4.8.15)

4.8.15 back-up ventilation DEPRECATED AS SYNONYM: apnea ventilation DEPRECATED AS SYNONYM: apnoea ventilation provision by which the ventilator automatically switches to a predetermined alternative ventilation mode intended to maintain patient safety in the event of a component, sensor or function becoming inoperable; or artificial ventilation by means of a second device in case of malfunction of the first

Note 1 to entry: The second device could be an operator-powered resuscitator.

Note 2 to entry: See also apnoea ventilation (4.8.14).

4.8.16 systematic ventilation-mode name systematised name for a ventilation mode, comprising elements that designate its ventilation- pattern, the selected inflation-type(s) and the type of provision for unassisted breathing, if provided

Note 1 to entry: The systematic name may be expressed as the full name but it is most useful in the more concise, coded form, using the abbreviated forms of the ventilation-pattern, the inflation-type(s) and the ACAP adjunct type, whenever this is a function of the ventilator. For examples of this coding scheme, see Table D.2 (Annex D).

Note 2 to entry: See also ventilation-pattern (4.8.3), inflation-type (4.2.2), Tables D.1a, D.1b, D.1c and D.2 (Annex D) and ACAP (assured constant airway pressure) (4.9.2).

4.8.17 alternative mode name alternative ventilation-mode name name used to identify a ventilation mode, or a specific setting protocol for a ventilation mode, which is alternative to the systematic ventilation-mode name, with the intention of placing emphasis on a particular characteristic feature of that ventilation mode or the manner in which it may be used

Note 1 to entry: The alternative name may identify a single ventilation mode, or several ventilation modes with the same characteristic feature or features.

Note 2 to entry: The alternative name may be either a standardised generic name or a proprietary name.

Note 3 to entry: The specification of an alternatively named ventilation mode is incomplete without reference to its systematic ventilation-mode name.

Note 4 to entry: The selection of a ventilation-pattern and inflation-types is fundamental to all modes but some ventilation modes have overriding, clinically significant, combinations of features that have been considered to justify their own generic or proprietary name. Such ventilation modes may use higher-order or interventional control

algorithms in order to achieve additional objectives, for example, a ventilation strategy or procedure, and which have therefore been identified solely by a name relating only to that objective. In other instances, specific combinations of ventilation-pattern, inflation-type(s) and range of settings have been characterised by a name that puts emphasis on a particular ventilation concept. Although this practice may be useful as a shorthand reference such mode names do not provide a complete description: a ventilation mode set on a ventilator using vocabulary conforming to that of this International Standard will enable identification of the standardised selected ventilation-pattern and selected inflation-type(s).

Note 5 to entry: Example of generic alternative names used in this vocabulary are bi-level ventilation and APRV (Airway Pressure Relief Ventilation).

4.8.18 superordinate mode one of a group of ventilation modes that has a significant additional feature to those of the underlying ventilation pattern-based mode, and by which it is separately identified

Note 1 to entry: The additional feature is typically a supervisory function that automatically makes adjustments to the controls of the ventilator with the intention of achieving a progressive care plan with the patient.

Note 2 to entry: Examples of proprietary superordinate-mode names are SmartCare™, Automode and ASV.

Note 3 to entry: See also alternative mode name (4.8.17)

4.8.19 breathing therapy mode ventilation mode that delivers a respirable gas at therapeutic breathing pressures to the patient’s airway with a primary intention other than to provide a proportion of the patient’s work of breathing

4.9 Mode Adjunct and Bi-level Terminology

4.9.1 adjunct ventilation-mode adjunct functional state of the ventilator that provides actions that are superimposed on those of suitable ventilation modes whenever they are selected

Note 1 to entry: Suitable ventilation modes are those that have the specific characteristics that the adjunct can modify to the potential benefit of the patient’s treatment.

Note 2 to entry: An installed ventilation-mode adjunct is typically permanently available and becomes active whenever a suitable ventilation mode is selected, but it may be selectable. Additional properties that are selectable by the operator in order to modify a specific ventilation-pattern or inflation-type are considered to be optional variations, not a mode adjunct.

4.9.2 ACAP assured constant airway pressure adjunct that enables unrestricted breathing by acting to maintain the airway pressure at its set value, irrespective of inspiratory or expiratory flows, or specified permitted leakage, whenever it is intended to be at a constant level

Note 1 to entry: This adjunct is intended to maintain the airway pressure at its set value with the exception of the inevitable minor deviations that are necessary for it to perform its function. Although there are currently no tests for acceptable levels for such deviations, they are expected to neither add to nor subtract from the patient’s perceived work of breathing to a greater extent than may be experienced during natural breathing.

Note 2 to entry: If the ventilator is connected to the patient with an airway device with sufficient resistance to hinder unrestricted breathing it is expected that its effect may be offset by the operator-selection of a tube compensation (TC) function.

Note 3 to entry: An ACAP adjunct is typically made possible in a microprocessor-controlled ventilator with a construction incorporating additional gas-control elements that are used to generate required airway-pressure waveforms irrespective of both inspiratory and expiratory flow and during both the inspiratory and expiratory phases of a primary-inflation. With this adjunct the patient is able to inspire and expire at any time at any BAP level; inspirations may be unassisted or supported and intended expiratory-pressure waveforms are maintained under the control of an expiratory-control algorithm. Unassisted inspirations are enabled by the provision of demand flow that is proportional to the patient’s demands, with no dependency on a patient-trigger event.

A typical implementation of ACAP on a gas-powered ventilator may involve the use of a proportional expiratory valve under the continuous control of the expiratory-control algorithm. When this is controlled in unison with the control of a proportional inspiratory valve it becomes possible to generate the required pressure waveform, irrespective of the possibly rapidly changing inspiratory and expiratory flows of natural breathing. This adjunct may also be achieved on a ventilator that uses alternative proportional gas control or generation elements.

Note 4 to entry: ACAP is typically preselected to be active wherever appropriate - depending on the ventilation mode that has been selected.

Note 5 to entry: Examples of instances of where ACAP is active, when provided, are

• during the intended constant-pressure portion of the waveform of a pressure-control (PC) primary-inflation, • after the expiratory pressure has stabilised at its BAP level during the expiratory phases of primary-inflation cycles and between any support inflations, • between any support inflations during CSV and continuously when pressure-support (PS) is set to ‘zero’ or ‘off, and • during CPAP ventilation modes.

Note 6 to entry: The constant pressure levels at which ACAP is active become the baseline airway-pressures for that activity.

Note 7 to entry: For unassisted breaths, an ACAP adjunct facilitates unrestricted breathing by the generation of demand flow in proportion to the patient’s demands, without any trigger threshold, during inspiration and by 4.2.12the provision of minimal resistance during expiration.

Note 8 to entry: Although this adjunct may not be required to maintain the baseline airway-pressure if pressure support is provided during an expiratory phase, it will serve to prevent the pressure dropping below the set baseline airway-pressure towards the end of expiration due, for example, to any ventilator breathing system or airway leakage. It also allows unrestricted breathing below the set trigger level, or when any pressure support is switched off.

Note 9 to entry: Some of the functions of ACAP may also be achievable by using specific settings with certain ventilator modes but, although such settings may be described as providing an equivalent function to ACAP, because its function is dependent on set values such an arrangement does not constitute an ACAP adjunct. If equivalence is claimed, the means used to facilitate unrestricted breathing should be described in the Instructions for Use.

Note 10 to entry: Group 2 ventilation-modes with an ACAP adjunct may be denoted by the alternative ventilation mode name bi-level ventilation.

Note 11 to entry: See also adjunct (4.9.1), unrestricted-breathing (4.1.5), natural-breathing (4.1.4), primary-inflation (4.2.12), baseline airway-pressure (4.11.1), bi-level ventilation (4.9.5) and demand flow (4.6.12).

4.9.3 ACAPL ACAP-low assured constant airway pressure, low adjunct that enables unrestricted breathing by acting to maintain the expiratory pressure at its set BAP baseline level, irrespective of inspiratory or expiratory flows, or specified permitted

© ISO 2016 – All rights reserved 59 ISO/DIS 19223:2016(E) leakage, after the expiratory pressure has decreased to its baseline level during the expiratory phases of primary-inflation cycles and between any support inflations

Note 1 to entry: As an adjunct that is only active during the expiratory phases of a primary-inflation cycles, it may be the most appropriate for use, for example, with a ventilation mode using a flow-regulated inflation-type as the primary-inflation.

Note 2 to entry: This adjunct is intended to maintain the airway pressure at its set value with the exception of the inevitable minor deviations that are necessary for ACAPL to perform its function. Although there are currently no tests for acceptable levels, with ACAPL, such deviations are expected to neither add to nor subtract from the patient’s perceived work of breathing to a greater extent than may be experienced during natural breathing.

Note 3 to entry: Where provided, ACAPL is typically preselected to be active wherever appropriate - depending on the ventilation mode that has been selected.

Note 4 to entry: For unassisted breaths, an ACAPL adjunct typically facilitates unrestricted breathing by the generation of demand flow in proportion to the patient’s demands, without any trigger threshold, during inspiration and by the provision of minimal resistance during expiration.

Note 5 to entry: Although this adjunct may not be required to maintain the baseline airway pressure if pressure support is provided during an expiratory phase, it will serve to prevent the pressure dropping below the set baseline airway pressure towards the end of expiration due, for example, to any ventilator breathing system or airway leakage. It also allows natural breathing below the set trigger level, or when any pressure support is switched off.

Note 6 to entry: Some of the functions of ACAPL may also be achievable with the use of specific settings with certain ventilation modes but, although such settings may be described as providing an equivalent function to ACAPL, because its function is dependent on set values such an arrangement does not constitute an ACAPL adjunct. If equivalence is claimed, the means used to facilitate unrestricted breathing should be described in the Instructions for Use.

Note 7 to entry: See also the Notes to entry 4.9.2, adjunct (4.9.1), baseline airway-pressure (4.11.1), demand flow (4.6.12) and primary-inflation (4.2.12).

4.9.4 ACAPH ACAP-high assured constant airway pressure, high mode adjunct that maintains the airway pressure at its set primary-inflation inspiratory-pressure value, irrespective of inspiratory or expiratory flows, whenever it is intended to be constant at that level

Note to 1 entry: This adjunct is provided for use only during the inflation phases of pressure-regulated primary- inflation cycles. ACAPH is not applicable during inflations with flow-regulated inflation-types, for example, volume- control, because the inspiratory pressure is not intended to be at a constant level during such inflations. If additional inspiratory flow is provided on demand with a volume-control inflation-type, this is classed as a dual-control inflation not volume-control with ACAP.

Note 2 to entry: This adjunct is intended to maintain the airway pressure at its set value with the exception of the inevitable minor deviations that are necessary for ACAPH to perform its function. Although there are currently no tests for acceptable levels, with ACAPH, such deviations are expected to neither add to nor subtract from the patient’s perceived work of breathing to a greater extent than may be experienced during natural breathing.

Note 3 to entry: Where provided, ACAPH is typically preselected to be active wherever appropriate - depending on the ventilation mode that has been selected.

Note 4 to entry: For unassisted breaths, an ACAPH adjunct facilitates unrestricted breathing by the generation of demand flow in proportion to the patient’s demands, without any trigger threshold, during inspiration and by the provision of minimal resistance during expiration.

Note 5 to entry: Some of the functions of ACAPH may also be achievable by using specific settings with certain ventilator modes but, although such settings may be described as providing an equivalent function to ACAPH, because

its function is dependent on set values such an arrangement does not constitute an ACAPH adjunct. If equivalence is claimed, the means used to facilitate unrestricted breathing should be described in the Instructions for Use.

Note 6 to entry: See also the Notes to entry 4.9.2, adjunct (4.9.1), baseline airway-pressure (4.11.1), dual-control (4.2.5) and primary-inflation (4.2.12).

4.9.5 bi-level ventilation bi-level alternative name for Group 2 modes with a pressure-control primary inflation-type and ACAP as an adjunct, where the intention is to place emphasis on the facility for unrestricted breathing at both baseline airway pressure levels of the primary-inflation cycle

Note 1 to entry: With the provision of ACAP, unrestricted breathing is possible at two alternating pressure levels, thereby adding to the ventilation provided by the primary, pressure- control inflations.

Note 2 to entry: It is common practice to also adopt an alternative naming scheme for the set and measured quantities that are affected by this intended change of emphasis. Figures in Annex E that illustrate modes that may be alternatively designated as bi-level ventilation also show how the alternative terms, standardised for that purpose, are used. Preferred and admitted terms for these quantities are listed in following entries in this sub-clause, 4.9.

Note 3 to entry: This is the generic name for a class of modes based on one originally introduced with the proprietary name BIPAP™ - which is not to be confused with the proprietary name BiPAP™

Note 4 to entry: See also Group 2 ventilation-modes (4.8.4.2), ACAP (4.9.2), bi-level PAP (Error! Reference source not found.), APRV (4.8.12) and Figure C.11a to d (Annex C).

4.9.6 bi-level positive airway pressure bi-level PAP BPAP sleep-apnoea breathing-therapy mode in which the positive airway pressure level that is therapeutically required during the inspiratory phase is reduced during each expiratory phase, with the sole intention of improving patient comfort

Note 1 to entry: The two levels of positive-airway-pressure (PAP) invoked by the various names that have been given to this breathing-therapy mode are typically identified by the terms IPAP and EPAP, with IPAP representing the required airway pressure level during the inspiratory phase and EPAP the lower airway pressure during the expiratory phase.

Note 2 to entry: This is the generic name for a breathing-therapy mode often identified by the proprietary name BiPAP™, which is not to be confused with the proprietary name BIPAP™.

Note 3 to entry: See also bi-level ventilation (Error! Reference source not found.).

4.9.7 BAP pressure-low pL alternatively named lower baseline airway-pressure level in ventilation modes labelled as bi- level ventilation

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: The admitted term and its symbol are included in this edition of this International Standard based on their common current usage and the possible need for a longer transition time for the change-over to the use of the term BAP, should this prove necessary.

Note 3 to entry: The use of this alternative term, or its admitted synonym, in modes labelled as bi-level ventilation is optional.

Note 3 to entry: See also BAP-high (Error! Reference source not found.), bi-level ventilation (Error! Reference source not found.), Figures C (Annex C) and Figure F.2 (Annex F).

4.9.8 pressure-low phase pL phase admitted synonym for BAP phase

Note 1 to entry: This admitted term and its abbreviation are included in this edition of this International Standard based on their common current usage as an alternative name for this concept and the possible need for a longer transition time for the change-over to the use of the term BAP phase, should this prove necessary.

Note 3 to entry: The use of this alternative admitted name, or its admitted abbreviation, in modes labelled as bi-level ventilation is optional.

Note 4 to entry: See also BAP phase (Error! Reference source not found.), bi-level ventilation (Error! Reference source not found.), BAP (Error! Reference source not found.), and BAP-high (Error! Reference source not found.).

4.9.9 time-low tL alternatively named duration of a BAP, or pressure-low, phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: This term is only relevant to modes labelled as bi-level ventilation and is only used in combination with the term BAP-high (or pressure-high) for the designation of the higher baseline airway pressure.

Note 3 to entry: See also baseline airway pressure (4.11.1), BAP-high (Error! Reference source not found.), bi-level ventilation (Error! Reference source not found.) time-high (Error! Reference source not found.) and Figures C.11c and d (Annex C).

4.9.10 BAP-high pressure-high pH alternatively named higher baseline airway-pressure level in modes labelled as bi-level ventilation

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 3 to entry: The use of this alternative term, or its admitted synonym, in modes labelled as bi-level ventilation is optional.

Note 4 to entry: See also BAP (4.16.3), bi-level ventilation (Error! Reference source not found.) and Figures C.11c and d (Annex C).

4.9.11 BAP-high phase pressure-high phase pH phase alternatively named primary inflation-phase in ventilation modes labelled as bi-level ventilation

Note 1 to entry: The admitted term and its symbol are included in this edition of this International Standard based on their common current usage and the possible need for a longer transition time for the change-over to the use of the term BAP-high phase, should this prove necessary.

Note 2 to entry: The use of this alternative term, or its admitted synonym, in ventilation modes labelled as bi-level ventilation is optional.

Note 3 to entry: See also bi-level ventilation (Error! Reference source not found.), BAP (4.11.1) and Figures C.11c and d (Annex C).

4.9.12 time-high tH alternatively named duration of a BAP-high (or pressure-high) phase

Note 1 to entry: In addition to its direct reference, this term may be used, in context or by qualification, to designate this concept as a set quantity (4.13.19) or a measured quantity (4.13.20).

Note 2 to entry: This term is only relevant to ventilation modes labelled as bi-level ventilation and is only used in combination with the term BAP-high (or pressure-high) for the designation of the higher baseline airway pressure.

Note 3 to entry: With inflations that provide synchronised termination the measured duration, averaged over several respiratory cycles, will be determined by the set time-high, even though the duration of any individual pressure-high phase may vary from the set rate as allowed by the synchronisation algorithm.

Note 4 to entry: See also bi-level ventilation (Error! Reference source not found.), baseline airway pressure (4.11.1), BAP-high (Error! Reference source not found.), BAP-high phase (Error! Reference source not found.), time-low (Error! Reference source not found.) and Figures C.11c and d (Annex C).

4.10 Initiation and termination terminology

4.10.1 initiate cause a process or action to begin

Note 1 to entry: This word has been adopted in this vocabulary as the general term to designate the concept of causing a process or action to begin. This is to counter a tendency to use the word ‘trigger’ for this purpose; a trend that removes the ability of that term to differentiate its own special meaning from that of a simple timed switching action. In this vocabulary an inflation can be initiated by, for example:

• patient-trigger events • timed signals • manual inputs • signals from a remote device

Note 2 to entry: In this vocabulary, an inflation that is initiated by a timed signal may is referred to as being ventilator-initiated.

Note 3 to entry: See also trigger (4.10.2), ventilator-initiation (4.10.12) and patient-trigger event (4.10.6).

4.10.2 trigger DEPRECATED: time trigger DEPRECATED: manual trigger DEPRECATED: remote trigger function that detects that the measured value(s) of a parameter(s) that can be attributed to the patient has reached a threshold value

Note 1 to entry: This is the definition of the basic concept of a trigger function, as the term is used in this vocabulary. In practice, some such functions may monitor the value of more than one parameter and make use of dedicated detection algorithms in order that sensitive settings can be used with a minimum risk of auto-triggering.

Note 2 to entry: This term is used to differentiate that class of inflation initiation signals that depend upon the attainment of a threshold by the measured value of a patient parameter, and hence involve a sensitivity setting, from those generated directly by the operation of simple timed, manual or remote, binary-switch functions.

Note 3 to entry: See also initiate (4.10.1) and patient-trigger event (4.10.6).

4.10.3 flow trigger function that detects when changes of flow in the ventilator breathing system due to inspiratory effort reach a set threshold level

Note 1 to entry: This is a classification for the means of detecting a patient’s inspiratory effort in generating a patient- trigger event. As explained in note 1 to4.10.2 , in practice, some such functions may monitor the value of more than one parameter and make use of dedicated detection algorithms in order that sensitive settings can be used with a minimum risk of auto-triggering. In a flow-trigger algorithm, flow will be the dominant parameter in determining attainment of the threshold level.

Note 2 to entry: The change of flow detected may be a change in the bias flow or a change in the flow through the patient-connection port.

Note 3 to entry: See also patient-trigger event (4.10.6), pressure trigger (4.10.4) and bias flow (4.6.8).

4.10.4 pressure trigger function that detects when pressure changes in the ventilator breathing system reach a set threshold level

Note 1 to entry: This is a classification for the means of detecting a patient’s inspiratory effort in generating a patient- trigger event. As explained in note 1 to 4.10.2 in practice, some such functions may monitor the value of more than one parameter and make use of dedicated detection algorithms in order that sensitive settings can be used with a minimum risk of auto-triggering. In a pressure-trigger algorithm, pressure will be the dominant parameter in determining attainment of the threshold level.

Note 2 to entry: The change of pressure detected may be a change in a measured pressure or a change in a rate of a pressure change.

Note 3 to entry: See also patient-trigger event (4.10.6), flow trigger (4.10.3) and bias flow (4.6.8).

4.10.5 trigger level threshold value for a trigger function

Note 1 to entry: This term is used, in context or by qualification, only to designate this concept as a set value (4.13.20).

Note 2 to entry: The level may be labelled in units of pressure or flow, or with a simple sensitivity scale.

4.10.6 patient-trigger event trigger-event signal resulting from a measured value(s) of a parameter(s), which can be attributed to the patient, reaching a threshold value

Note 1 to entry: Typical patient respiratory parameters that are monitored for this purpose are airway pressure, flow or volume, and electromyography signals (EMG). Far less commonly used parameters are chest-wall motion and transthoracic impedance. The detection algorithm may involve more than one of these parameters.

Note 2 to entry: An inflation initiated by a patient-trigger event may be referred to as being patient-triggered or by the method of detection, for example, pressure-triggered, flow-triggered, etc.

Note 3 to entry: The initiation of an inflation by means of a manual input is not a manual trigger event; it is a manual initiation.

Note 4 to entry: It is important that users are made aware that a patient-trigger event may result from the detection of a spurious perturbation on a measurement, especially if the threshold value is set at too sensitive a level.

Note 5 to entry: See also trigger (4.10.2) and auto trigger (4.10.10).

4.10.7 breath synchronization timing adjustment of each initiation and/or termination of an assured delivery so as to match the pattern of any spontaneous inspiratory and/or expiratory efforts, while still maintaining the set rate

Note 1 to entry: Any such timing adjustment will alter the respiratory cycle time of the assured delivery, breath to breath, but the average delivery rate will be maintained at set value.

4.10.8 synchronisation window time interval following the scheduled initiation or termination, of an assured delivery during which actual initiation or termination of an inflation may be synchronised with a respiratory activity of the patient

Note 1 to entry: See Figures C.10, C.11c, C.11d and C.14d (Annex C) for illustrations of the function of a synchronisation window.

4.10.9 mandatory required to occur

Note 1 to entry: This term is defined as used in this vocabulary, with a specific meaning of the word mandatory, which in natural language has a spectrum of meanings. It has become firmly established in the vocabulary of artificial ventilation but because of its ambiguity it can denote either ‘total control’ or, as in this definition, ‘required to occur’. In early artificial ventilation practice it was usual for all aspects of the patient's ventilation to be taken over by the ventilator and so every breath could be described as mandatory in its broadest sense. Since then, with the introduction of patient triggering and the concept of support for spontaneous breathing, only a small percentage of patients currently have their ventilation totally controlled. However, there remains a mandatory component to all forms of artificial ventilation but a key aspect for an operator when setting a modern ventilator is being assured that, when a selected inflation occurs within the selected ventilation-pattern, it will provide a minimum level of assistance and, in the case of apnoea, that the ventilation will be totally controlled.

These developments have led manufacturers to increasingly restrict the use of the term ‘mandatory’ to the context of ventilation that is assured to occur by the programmed delivery of a selected inflation-type, in predetermined patterns, independent of the patient's respiratory activity. This is the only sense in which the term mandatory is used in this vocabulary; which is mainly in the explanation of the classical mode names such as continuous mandatory

ventilation, intermittent mandatory ventilation and synchronised intermittent mandatory ventilation. For other purposes, wherever possible, the term assured is used in its place.

Note 3 to entry: See also assured delivery (4.2.14) and assured minute volume (4.7.11).

4.10.10 auto trigger DEPRECATED AS SYNONYM: autocycle initiation of an inflation as a result of a false patient-trigger event

Note 1 to entry: A false patient-trigger event may be caused, for example, by external perturbations such as a movement of the breathing tube or a cardiac impulse creating pneumatic disturbances.

4.10.11 breath stacking situation in which the ventilator delivers another inflation, or the patient makes an inspiratory effort, before the previous breath has been adequately expired

Note 1 to entry: This situation may be caused by auto triggering or by the expiratory time being set to be too short.

4.10.12 ventilator-initiation initiation of an inflation by means of a timed signal generated after a set interval

4.10.13 remote inflation-initiation initiation of an inflation by means of a recognised signal caused by an event external to the ventilator

EXAMPLES: a signal from another medical device; a synchronization signal from x-ray equipment

4.10.14 termination DEPRECATED: cycle bringing to an end

Note 1 to entry: In this vocabulary this term is used in reference to the ending of either of the two principal breath phases. The means of termination constitutes the secondary classification of inflation-types.

Note 2 to entry: See also inspiratory-termination flow (4.6.3) and expiratory-termination flow (4.6.6).

Note 1 to deprecated term: The term ’cycle’ is currently commonly used in some countries with the meaning of ‘termination’ but it is, in fact, an abbreviation of ‘cycle-off’’. These terms originated when ventilators simply cycled between ‘on’ and ‘off’. Typically, ventilators are now equipped with a variety of means to terminate an inflation and the term ‘cycle’ is considered to be misleading in this context; it also causes confusion with the true dictionary meaning of the term ‘cycle’ as used in this vocabulary.

4.10.15 flow-termination DEPRECATED: flow cycled termination of a pressure-regulated inflation, or of an expiratory phase, as a result of a reduction of the phase flow to the set termination-flow threshold

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.20).

Note 2 to entry: This method of termination provides the means for the patient's respiratory activity to be used to influence the duration of an inflation or expiratory phase in order to improve the match of the duration with the patient's own breathing pattern. See pressure-support for an example of an inflation-type that is typically pressure- regulated and flow-terminated.

Note 3 to entry: Patient-safety considerations dictate that a time-termination is provided as a backup where flow- termination is the intended to be the primary means of termination. This time-termination may be preset, operator adjustable or set by an algorithm.

Note 4 to entry: Flow-terminated pressure-support inflation-types have often been referred to as patient-terminated. The use of that term is deprecated in this vocabulary unless the ventilator is able to specifically indicate that the termination is due to the patient's respiratory activity and neither due to the inevitable decline in inspiratory flow as the passive lungs are inflated in the absence of any such activity, nor due to time-termination.

Note 5 to entry: See also pressure-support 4.2.6), end-inspiratory flow (4.6.4) and end-expiratory flow (4.6.7).

4.10.16 pressure-termination DEPRECATED: pressure cycled termination of an inflation phase when the inspiratory pressure attains a set level

Note 1 to entry: The set level may be either the primary termination criterion for the inflation-type or a set safety limit for the protection of the patient during normal condition or under a single fault condition.

Note 2 to entry: See also normal condition (4.13.26), single fault condition (4.13.27), pressure limit (4.12.1.1) and pressure control (4.2.4).

4.10.17 time-termination DEPRECATED: time cycled termination of an inflation or expiratory phase after an elapsed time, either as set or as derived by an algorithm

Note 1 to entry: Patient-safety considerations dictate that all inflation-types have a directly or indirectly set time- termination. It may be the operator-set primary means of termination or it may be a preset back-up to an alternative primary means of termination

4.11 Baseline and PEEP terminology

4.11.1 BAP baseline airway-pressure baseline pressure PEEP reference airway-pressure level that may be positively offset from the ambient pressure by a set amount and at which a patient breathes when unassisted and upon which inflations are superimposed

Note 1 to entry: The acronym BAP is employed in this vocabulary for the designation this concept as a set quantity (4.13.19) and in reference to baseline levels at a set level. The full term is used in reference to the concept and its function. For examples of this usage see the notes to sub-clauses relating to baseline airway pressure and the relevant sub-clauses in 4.9 and 4.11.

Note 2 to entry: Because of its established use, the acronym PEEP is retained as an admitted term to designate the setting for the baseline airway-pressure level, in this edition of this International Standard. This is in order to provision for a longer transition time in the change-over to the use of the term BAP, should this prove necessary. It may also remain to be a more appropriate term for a setting on basic ventilators and resuscitators, where the concept of a baseline airway pressure is not relevant.

Note 3 to entry: The baseline airway-pressure level for humans breathing without a ventilator is that of the ambient environment. Most ventilators have the capability for the patient to be ventilated and be able to breathe, with a baseline pressure level(s) that is artificially raised relative to the ambient pressure. In addition to the baseline at ambient pressure, this vocabulary utilises baselines at the set BAP level (see note 4 to entry); at the set primary- inflation inspiratory-pressure level (see note 6 to entry); and at the set level in CPAP ventilation modes (see note 8 to entry). In modes designated as bi-level ventilation the baseline at the inspiratory pressure level may be designated as BAP-high.

Note 4 to entry: Baselines at the set BAP level become the reference level for,

• the intended minimum alveolar pressure level throughout expiratory phases of inflations initiated from that baseline, • any inflation-cycles initiated from that baseline, • an ACAP adjunct if active at that level, • the expiratory-control algorithm for any inflation-cycles initiated from that baseline, and • the intended PEEP (positive end-expiratory pressure) at the patient connection port.

Note 5 to entry: The adoption of the concept of a baseline at a set BAP level, to replace that of a PEEP setting, which only determines a positive pressure at the end of each expiratory phase, is necessary because of the increasing number of ventilators that incorporate ventilation-mode adjuncts. These are able to generate required airway pressure waveforms irrespective of both inspiratory and expiratory flow and during both inspiratory and expiratory phases of a primary-inflation. With such an adjunct activated the patient is able to inspire and expire at any time at any BAP level. Such inspirations may be unassisted or supported and intended expiratory-pressure waveforms are maintained under the control of an expiratory-control algorithm. Unassisted inspirations are enabled by the provision of demand flow that is proportional to the patient’s demands, with no dependency on a patient-trigger event. The possibilities that such functions open up require a vocabulary that includes the concept of one or more continuous baseline airway pressures in addition to one that only specifies a pressure requirement at the end of an expiratory phase.

Note 6 to entry: If an ACAP adjunct is provided during a pressure-control (PC) primary-inflation the set inspiratory pressure level becomes the baseline for,

• any concurrent support inflations initiated from that baseline, • the ACAP adjunct at that level, and • the expiratory-control algorithm for any inflation cycles initiated from that baseline.

Note 7 to entry: Ventilation modes in which ACAP is always active, at both the BAP and inspiratory pressure levels, may alternatively be labelled as bi-level ventilation modes.

Note 8 to entry: In a CPAP ventilation mode, the baseline at the set CPAP pressure level becomes the reference level for the ACAP adjunct that enables continuous unrestricted breathing at that constant level.

Note 9 to entry: See also PEEP (4.11.2), ACAP (4.9.2), bi-level ventilation (4.9.5), CPAP (4.8.13), BAP phase (4.3.3) BAP-high (4.9.10) and Figures C11 (Annex C).

4.11.2 PEEP positive end-expiratory pressure respiratory pressure at the end of an expiratory phase

Note 1 to entry: In addition to its direct reference, this term or its acronym, is used in this vocabulary to designate this concept as a measured quantity. Without qualification the quantity is always that at the patient connection port and relative to ambient pressure. When used as part of a post-coordinated term it may be attributed to other measurement sites or reference pressure levels. The term, in its acronym form only, may also be used as an admitted term for the designation of the set value of the baseline airway pressure level (which encompasses the setting for the end-expiratory pressure), thereby acting as a synonym for BAP. For further information on PEEP as an admitted term see 4.11.1.

Note 2 to entry: As a measured quantity, the qualification ‘positive’ is not strictly necessary but its use is retained because it places emphasis on one of the main purposes for which PEEP is used: that of wanting to retain at least a minimum ‘positive’ pressure in the alveoli in order to guard against their collapse.

Note 3 to entry: Since its early use, this term has been used to designate this concept as both a setting and measured value with very little clarity as to which. As the term for a measurement it has been post-coordinated to form terms such as auto-PEEP, intrinsic PEEP, alveolar PEEP, total PEEP, dynamic intrinsic PEEP, dynamic extrinsic PEEP, dynamic total PEEP and applied PEEP. The term extrinsic PEEP has also been used to designate the PEEP at the patient connection port but it is usually not clear whether that is for the set or the actual value. Although, ideally both will have the same value the actual value is not dependent on the set value alone and may have a higher or lower value, depending on other factors such as the expiratory time, any ventilator breathing system or airway device leakage, or patient effort. An inspection of current ventilator labelling demonstrates that there is very little consistency in the way these various forms of the term are used and what they designate.

In practice, on modern electronically controlled ventilators, there is still only the need for one term for the designation of the intended PEEP but a need for an increasing number of terms to designate the various measured outcomes that can be displayed. With the increased significance of the concept of a baseline airway-pressure on such ventilators (for further information see 4.11.1), and because the intended PEEP is simply a specific point on that baseline, there is now a strong case for using the set BAP as the designator for both. This then leaves the acronym PEEP, along with its various post-coordinations, free to designate only measured quantities on those ventilators where there are one or more measured values to be displayed or recorded. However, on basic ventilators and resuscitators, where the concept of baselines is not relevant, and where no independent measured PEEP values are displayed or recorded, then it is logical to retain PEEP as the designator for the set value. These considerations are the basis for the notation adopted in this vocabulary.

Note 4 to entry: The measured value of this quantity informs the operator as to how closely the actual airway pressure at the end of expiration corresponded with the set BAP value. Ideally, it will have the same value as the set BAP, but is not dependent on this setting alone and may, therefore, have a higher or lower value, depending on other factors such as the expiratory time, any ventilator breathing system or airway device leakage, or patient effort.

Note 5 to entry: See BAP (4.11.1) for further information on the context in which PEEP is used in this vocabulary.

Note 6 to entry: See also total PEEP (4.11.4), dynamic PEEP 4.11.5) and F.1 (Annex F).

4.11.3 expiratory-control algorithm algorithm that determines the expiratory-pressure waveform of an expiratory phase

Note 1 to entry: The algorithm used for a specific mode is specified by the manufacturer.

Note 2 to entry: The expiratory-control algorithm takes the relevant baseline airway-pressure as its reference throughout the corresponding phases. See note 1 to the baseline airway pressure entry (4.11.1).

Note 3 to entry: The main purpose of the algorithm is that of managing the expiratory-pressure waveforms following inflations and unassisted inspirations in order to achieve a required objective(s) throughout each expiratory phase.

Note 4 to entry: A basic expiratory-control algorithm may be no more than that of switching the expiratory valve to its open state, leaving the expiratory flow waveform and the minimum expiratory pressure to be determined by an expiratory pressure-relief function (commonly known as a PEEP valve), which is set to the required BAP level. This relieves expiratory pressure by allowing expiratory flow to pass through to the exhaust port with minimal resistance when above the BAP level, but which prevents expiratory flow below that level. However, with this arrangement, once the expiratory flow has ceased, any leakage from the ventilator breathing system or from an airway device may cause the pressure to continue to fall so that by the end of expiration the measured airway-pressure, PEEP, could be below that set. For further information on expiratory pressure-relief see 4.5.10.

Note 5 to entry: An increasing number of ventilators now incorporate ventilation control functions that are able to generate required expiratory-pressure waveforms irrespective of both inspiratory and expiratory flow during both the inspiratory and expiratory phases of a primary inflation. With these functions activated the patient is able to inspire and expire at any time at either the BAP or the primary-inflation inspiratory pressure (or BAP-high) level. These inspirations may be unassisted or supported.

During expirations an expiratory-control algorithm may be used to continuously control the expiratory-pressure waveform in order to achieve an optimum rate of pressure decay. This may include, for example, achieving a faster lung deflation rate by temporarily reducing the airway pressure below the baseline level in early expiration but

bringing it back up to baseline pressure early enough to ensure that the pressure in the lungs never decreases below the baseline level during that phase

With this function acting alone during a BAP phase, an unassisted inspiration may incur additional work of breathing, and if there is a leak in the ventilator breathing system or at the connection to the patient, the airway pressure may fall towards the ambient pressure, which will result in a loss of the intended PEEP. Such consequences may be mitigated by the provision of a bias flow or prevented by the provision of demand flow or an ACAP adjunct, active at the BAP level.

Note 6 to entry: See also the notes to the baseline airway-pressure entry (4.10.1), Figure F.1 and Figures F.3a to d (Annex F).

4.11.4 total PEEP tPEEP DEPRECATED: intrinsic PEEP DEPRECATED: auto PEEP airway pressure at the end of an expiratory-hold procedure that temporarily occludes the upper airway, in the absence of any respiratory effort

Note 1 to entry: In addition to its direct reference, this term is only used in this vocabulary, in context or by qualification, to designate this concept as a measured quantity (4.13.20).

Note 2 to entry: As the pressure at the patient-connection port falls during expiration, there is an unavoidable dynamic lag in the corresponding rate of fall of the alveolar pressure, mainly due to airway-resistance and flow limitation factors. Normally, the effects of this lag will have fully dissipated by the end of the expiratory phase, but with shorter expiratory times or with diseased lungs, the average alveolar pressure may still be above the measured expiratory pressure at the end of the expiratory phase. The amount by which this average alveolar pressure exceeds the measured positive end-expiratory pressure, PEEP, cannot be measured directly but its presence and order of magnitude is commonly ascertained by the use of an expiratory-hold procedure. The airway pressure measurement at the end of this procedure is the average of that of the pressurised gas in the alveoli that has been able to distribute uniformly throughout the lung during the expiratory-hold time, but it may not fully include the contribution of any trapped gas to the true average pressure.

Note 3 to entry: This term is typically only used in relation to the ventilation of patients with diseased lungs, where the presence of dynamic PEEP may be indicated or suspected. In the absence of any dynamic PEEP, a measured total PEEP has the same value as the measured PEEP for the same expiration and, therefore, has no relevance, other than to show that there is no dynamic PEEP.

Note 4 to entry: Because of the diverse nature of diseased lungs there is currently no precise definition of a single concept of total PEEP in an artificially ventilated patient, other than the value measured at the end of an inspiratory- hold procedure during which there is no respiratory effort. This has, therefore, been adopted as the reference method for the determination of the value of this quantity in this vocabulary although a substantially equivalent value may be determined by other methods.

Note 5 to entry: See also dynamic PEEP (4.11.5), PEEP (4.11.2), baseline airway-pressure (4.11.1), and Figures F.1a – F.1d (Annex F).

Note 1 to deprecated terms: These terms are deprecated as synonyms for total PEEP in this vocabulary because, although they are both widely used, there is a clear lack of consensus in the scientific literature and in manufacturer’s labelling as to whether either or both refer to total PEEP or dynamic PEEP.

4.11.5 dynamic PEEP dPEEP DEPRECATED: intrinsic PEEP DEPRECATED: auto PEEP portion of total PEEP that is above PEEP

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured quantity (4.13.20)

Note 2 to entry: As the pressure at the patient-connection port falls during expiration, in the absence of respiratory efforts there is an unavoidable dynamic lag in the corresponding rate of fall of the alveolar pressure, mainly due to airway-resistance and flow limitation factors. Dynamic PEEP represents the portion of total PEEP resulting from this dynamic lag that would not have been present if the expiratory (or BAP) time had been extended by the duration of the expiratory hold.

Note 3 to entry: If there is insufficient expiratory time for the expiratory pressure to reach its baseline airway-pressure level before the end of expiration then PEEP will be greater than that intended by the BAP setting.

Note 4 to entry: See also total PEEP (4.11.4), PEEP (4.11.2), baseline airway-pressure (4.11.1), and Figures F.1a – F.1d (Annex F).

Note 1 to deprecated terms: These terms are deprecated as synonyms for dynamic PEEP in this vocabulary because, although they are both equally widely used, there is a clear lack of consensus in the scientific literature and in manufacturer’s labelling as to whether either or both refer to dynamic PEEP or total PEEP.

4.11.6 delta PEEP ΔPEEP quantity by which PEEP exceeds BAP

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a measured or calculated quantity (4.13.20).

Note 2 to entry: Typically there will be no difference between PEEP and the set BAP, but where a difference arises the operator should be aware of the possible implications. A positive difference may indicate too short an expiration time or a restriction in the ventilator’s expiratory pathway (for example, a contaminated filter). A negative difference may indicate that the alveolar pressure is being allowed to drop below the intended minimum level due to uncompensated leakage from the ventilator breathing circuit or at the airway device.

Note 3 to entry: See also Figure F.1a – F.1d (Annex F), BAP (4.11.1) and PEEP (4.11.2).

4.12 Safety limits and alarm terminology

4.12.1 Safety limits 4.12.1.1 pressure limit airway-pressure limit airway-pressure threshold value for the initiation of an action to protect the patient during normal use

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: This is a general, pre-coordinated term that is the basic definition for high and low limitation functions and for associated functions such as defining alarm conditions and other means of protection.

Note 3 to entry: The limit is to be taken to be for a rising pressure unless specified otherwise. This not only accords with common usage but also avoids a possible confusion resulting from the use of the word ‘high’, which is used in

the limit and alarm terms in this vocabulary with a meaning of ‘higher than intended’, as distinct from ‘the opposite of low’.

Note 4 to entry: See also limit (4.13.23).

4.12.1.2 pressure-limited pLim inspiratory pressure limited to the set pressure limit during normal use, by means of an inspiratory pressure relief function

Note 1 to entry: This limitation is typically used in conjunction with volume control inflation-types where the intention is to limit the maximum pressure that can be generated at the patient connection port during normal use

Note 2 to entry: A pressure relief function spills excess regulated flow to atmosphere, if necessary to avoid the inspiratory pressure exceeding the set level. This results in a possibly un-quantified loss of the delivered volume. See also inspiratory pressure relief (4.5.5).

Note 3 to entry: This function may be associated with an alarm condition.

Note 4 to entry: See Figure C.2 (Annex C) for an example of a pressure limited inflation.

4.12.1.3 maximum limited pressure maximum limited airway-pressure DEPRECATED: maximum circuit pressure limit highest airway pressure during normal use or under single fault condition

Note 1 to entry: In addition to its direct reference as a requirement, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: As with all unqualified airway pressures, this limited pressure is that at the patient connection port and relative to ambient pressure.

Note 3 to entry: As this is the highest level precaution against excessive pressures being applied to the patient’s airway this is a manufacturer’s set value.

[SOURCE: ISO/IEC 80601-2-12: 2011, modified by the addition of semantic notes.]

4.12.1.4 maximum deliverable airway-pressure DEPRECATED: maximum working pressure maximum airway pressure that can be generated by the ventilator during intended use and normal condition

Note 1 to entry: This information is usually documented in the instructions for use as it is valuable to determine whether a ventilator is suitable for use with a particular patient with poor lung compliance.

4.12.1.5 high-airway-pressure limit threshold value at which a protection device prevents any further rise in the airway pressure

Note 1 to entry: The protection device may maintain the pressure at a level close to the threshold value, reduce the pressure to the set baseline airway pressure (BAP) or terminate the inflation phase. One or more of these alternatives will be required by the particular standard that covers the class of ventilator to which the term may be applied.

Note 2 to entry: The set limit may be:

• independently adjustable • connected to an adjustable pressure limit • connected to the high airway pressure-alarm limit • related to the set inflation pressure.

Note 3 to entry: See also inspiratory pressure relief (4.5.5)

4.12.1.6 high-pressure relief limit high-airway-pressure relief limit airway pressure threshold value used by a ventilator to determine when a protection device prevents any further rise in airway pressure during normal use

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: As with all unqualified airway pressures, this limited pressure is that at the patient connection port and relative to ambient pressure.

Note 3 to entry: During an inflation, the high pressure relief protection device is intended to maintain the airway pressure at the threshold value, without terminating the inflation.

Note 4 to entry: Activation of this form of airway pressure limitation will often cause a drop in the inspiratory volume. Operator awareness of this characteristic may be important for patient safety.

Note 5 to entry: The set limit may be independently adjustable, linked with an adjustable pressure limitation, related to the set inspiratory pressure or determined by an algorithm but it must always be at a higher value than the maximum inspiratory-pressure that will result from the operator’s settings during normal use.

Note 6 to entry: The set limit may be associated with an alarm limit.

Note 7 to entry: See also high pressure termination limit (4.12.1.7)

4.12.1.7 high-pressure termination limit high-airway-pressure termination limit airway pressure threshold value used by a ventilator to determine when a protection device terminates the current inflation phase during normal use

Note 1 to entry: This form of airway pressure limitation will often result in the delivered volume falling below the intended tidal volume. Operator awareness of this characteristic is important for patient safety.

Note 2 to entry: As with all unqualified airway pressures, this limited pressure is that at the patient connection port and relative to ambient pressure.

Note 3 to entry: The set limit may be independently adjustable, connected to an adjustable pressure limitation, may be related to the set inflation pressure or may be determined by an algorithm but it must always be at a higher value than the maximum inspiratory-pressure that will result from the operator’s settings during normal use.

Note 4 to entry: This function may be associated with an alarm condition. Particular Standards may have specific requirements

Note 5 to entry: This may have the same as or different threshold from the high-airway-pressure alarm condition. Particular Standards may have specific requirements

Note 6 to entry: See also high pressure relief limit (4.12.1.6) and Figure C.2c (Annex C).

4.12.1.8 maximum settable inspiratory pressure maximum inspiratory-pressure that can be set by the operator

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19), which will typically be pre-set by the manufacturer or the responsible organization

Note 2 to entry: As with all unqualified airway pressures, this inspiratory pressure is that at the patient connection See inspiratory pressure (4.5.2). port and relative to ambient pressure unless prefixed with ‘delta’ or the symbol Δ. 4.12.1.9 adjustable pressure limit adjustable airway pressure limit APL operator-set limitation on the airway pressure under normal condition

EXAMPLE: APL valve on anaesthesia breathing system

4.12.2 Alarm conditions 4.12.2.1 alarm condition state of the alarm system when it has determined that operator awareness or response is required for a potential or actual hazardous situation

Note 1 to entry: An alarm condition can be invalid, that is, a false positive alarm condition.

Note 2 to entry: An alarm condition can be missed, that is, a false negative alarm condition

Note 3 to entry: The alarm condition may be patient related, technical, healthcare provider related or environmental

Note 4 to entry: This definition has been submitted to the ISO/IEC joint working group on Medical Device Alarm Systems for inclusion in the next edition of IEC 60601-1-8

Note 5 to entry: It is intended that the term alarm condition be used by standards writers within post-coordinated terms, for example, high spontaneous breathing rate alarm condition

[SOURCE: IEC 60601-1-8 2006+A1:2012 Clause 3.1, modified]

4.12.2.2 high-pressure alarm condition high-airway-pressure alarm condition alarm condition resulting from a high airway pressure

Note 1 to entry: The high-airway-pressure alarm condition may be subject to an alarm condition delay or there may be an alarm signal generation delay after the onset of an alarm condition.

Note 2 to entry: This may have the same or a different threshold than the high-pressure relief or termination limit. Particular standards may specify specific requirements for such alternative possibilities.

Note 3 to entry: As with all unqualified airway pressures, this alarm limit pressure is that at the patient connection port and relative to ambient pressure.

Note 4 to entry: See also high-airway-pressure relief limit (4.12.1.6) and high-airway-pressure termination limit (4.12.1.7).

4.12.2.3 continuing pressure alarm condition continuing airway-pressure alarm condition alarm condition resulting from an airway pressure that has remained at or exceeded a threshold level for a threshold length of time

Note 1 to entry: The threshold level and length of time will be as disclosed in the instructions for use.

Example: An alarm condition determined when the airway-pressure is held at the set inspiratory-pressure for 3 seconds longer that the set inspiratory time.

Example: In an anaesthesia ventilator breathing system (anaesthesia VBS) in CSV mode with the airway pressure limit valve closed or partially closed with medical gas flowing into the VBS.

4.12.2.4 low inspiratory-pressure alarm condition state of the alarm system when it has determined that operator awareness or response is required for a potential or actual hazardous situation caused by low inspiratory airway pressure

4.12.2.5 low PEEP alarm condition alarm condition determined when the end-expiratory pressure is less than the set BAP

4.12.3 Alarm limits 4.12.3.1 alarm limit threshold used by an alarm system which likely differentiates between safe use (tolerable risk) and potential or actual harm

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: The set alarm limit parameter may be independently adjustable, linked with an adjustable parameter limitation, related to a set parameter or determined by an algorithm.

Note 3 to entry: This definition has been submitted to the ISO/IEC joint working group on Medical Device Alarm Systems for inclusion in the next edition of IEC 60601-1-8

[SOURCE: IEC 60601-1-8 2006+A1:2012 Clause 3.3, modified]

4.12.3.2 high-airway-pressure alarm limit upper airway pressure threshold used by an alarm system which likely differentiates between safe use (tolerable risk) and potential or actual harm

Note 1 to entry: the threshold is always greater than the maximum inspiratory pressure intended by the operator’s settings

Note 2 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 3 to entry: The set high-airway-pressure alarm limit may be independently adjustable, connected to an adjustable pressure limitation or may be related to the set inspiratory pressure.

Note 4 to entry: The high-airway-pressure alarm limit setting may be different from that of the high-pressure limit.

4.12.3.3 low inspiratory-pressure alarm limit lower airway pressure threshold used by an alarm system which likely differentiates between safe use (tolerable risk) and potential or actual harm

Note 1 to entry: In addition to its direct reference, this term is only used, in context or by qualification, to designate this concept as a set quantity (4.13.19).

Note 2 to entry: The set low-inspiratory-pressure alarm limit may be independently adjustable or may be related to the set inspiratory pressure.

4.13 General artificial ventilation terminology

4.13.1 ventilator lung ventilator medical device or medical electrical equipment intended to automatically contribute to, or totally control, the ventilation of the lungs of the patient

Note 1 to entry: See also ventilation (4.13.6).

[SOURCE: ISO 80601-2-12:2011, definition 201.3.222 modified]

4.13.2 airway connected, gas-containing cavities and passages within the respiratory system, that conduct gas between the alveoli and the oral and nasal orifices on the surface of the face, or the patient- connection port if an airway device is used

Note 1 to entry: This is a well-established term that is commonly used in isolation in references to the airway of a patient. Depending on the context, it is sometimes more helpful to use the qualified term, patient’s airway.

Note 2 to entry: See also airway device (4.13.3).

4.13.3 airway device device intended for use as an interface between the patient-connection port of a ventilator and the patient's airway, and which has no auxiliary features on which the ventilator is dependent for its normal operation

EXAMPLES: endotracheal tube; tracheotomy tube; face mask; supralaryngeal airway.

Note 1 to entry: The connection to the patient’s airway may be at the face or internal to the patient.

Note 2 to entry: A face mask that intentionally vents respiratory gas to atmosphere by means of a bleed orifice is a functional part of the ventilator breathing system and therefore not an airway device. With that arrangement the face seal of the mask becomes the patient-connection port and there is no patient-connection port connector, nor an airway device.

4.13.4 airway resistance drop in pressure between the patient connection port and the alveoli per unit rate of airway flow

Note 1 to entry: The airway resistance is normally expressed as a single coefficient, with the implicit assumptions that it is independent of the flow rate and of the direction of flow. In practice, these assumptions are typically only approximately valid.

Note 2 to entry: See also airway (4.13.2).

4.13.5 lung compliance measure of the ability of the lung to expand, expressed as the unit change of lung volume required to achieve unit change of transpulmonary pressure

Note 1 to entry: The lung compliance is normally expressed as a single coefficient, with the implicit assumptions that it is independent of the volume of gas in the lung and of any hysteresis between increasing and decreasing volumes. In practice, these assumptions are typically only approximately valid.

4.13.6 ventilation movement of gas into and out of the lungs

Note 1 to entry: This may be by external or spontaneous means, or by a combination of both.

Note 2 to entry: See also spontaneous breath (4.1.3), artificial ventilation (4.13.7), automatic ventilation (4.13.8), mechanical ventilation (4.13.8), negative-pressure ventilation (4.13.11), positive-pressure ventilation (4.13.10) and inflation (4.2.1).

4.13.7 artificial ventilation ventilation in which a non-zero proportion or all of the work of breathing is provided by external means

Note 1 to entry: Examples of the means used to provide artificial ventilation are: manual resuscitation; mouth-to- mouth resuscitation; automatic ventilator; mechanical ventilator; manually-triggered resuscitator.

Note 1 to entry: Common classifications of areas of application of artificial ventilation are: emergency; transport; home-care; anaesthesia; critical care; rehabilitation.

Note 2 to entry: Classifications used to denote means used for artificial ventilation include: positive-pressure; negative-pressure; gas-powered; operator-powered; electrically-powered.

4.13.8 automatic ventilation continuous artificial ventilation by means of an automatic device

Note 1 to entry: With automatic ventilators within the scope of this International Standard, artificial ventilation is achieved by the use of positive-pressure ventilation.

4.13.9 mechanical ventilation continuous artificial ventilation by means of a mechanical device

Note 1 to entry: This term has become the commonly used term for any form of artificial ventilation that involves a specifically designed equipment having several mechanical or electrical/electronic parts.

Note 2 to entry: A mechanical ventilator may provide artificial ventilation automatically or by manual operation and may provide positive-pressure ventilation or negative-pressure ventilation.

4.13.10 positive-pressure ventilation DEPRECATED AS SYNONYM: IPPV artificial ventilation achieved by the intermittent elevation of the airway pressure above the set baseline airway pressure

Note 1 to entry: This is a general term for artificial ventilation achieved by the intermittent application of a raised pressure to some part of the patient’s airway in order to assist or control an increase in the volume of gas in the lung. Each such intermittent elevation of the airway pressure constitutes an inflation.

Note 2 to entry: The original term for this means of applying artificial ventilation was intermittent positive-pressure ventilation (IPPV) but since the almost universal adoption of the practice of retaining some level of positive airway pressure at the end of expiration the ‘positive pressure’ is no longer intermittent because the airway pressure is continuously positive. Although it is only possible to achieve positive-pressure artificial ventilation by intermittently changing the airway pressure, whether it is intermittent elevation or intermittent release of the pressure depends on the objective and settings. With its now wide acceptance in the practice of artificial ventilation, the qualifying term ‘positive-pressure’ is, therefore, all that is required to distinguish it from alternative means of artificial ventilation.

Note 3 to entry: See also inflation (4.2.1), airway pressure (4.5.1) and baseline airway pressure (4.11.1).

4.13.11 negative-pressure ventilation NPV artificial ventilation achieved by intermittently changing a negative pressure applied to the exterior of the patient's thorax

Note 1 to entry: Although many of the terms will be common, the scope of this edition of this International Standard does not include vocabulary specific to negative-pressure ventilation.

Note 2 to entry: See Scope (1)

4.13.12 non-invasive ventilation NIV positive-pressure ventilation without the use of an invasive airway device

Note 1 to entry: The connection to the patient is typically by means of a specially designed face or nasal mask.

Note 2 to entry: This vocabulary is equally applicable to non-invasive ventilation (NIV) systems but the modes and settings made available for intended non-invasive ventilation use may be specifically adapted to accommodate the particular characteristics and uncertainties of that procedure.

Note 3 to entry: In this vocabulary, this term is not applicable to the designation of breathing therapy equipment as a class separate from ventilation equipment.

4.13.13 tube compensation TC assistive offset of pressure provided by the ventilator during the inspiratory phase of an unassisted or assisted spontaneous breath, or during an expiratory phase, solely in order to compensate, at least in part, for the added airway resistance imposed by an airway device

Note 1 to entry: Tube compensation is not classified as an inflation-type because its intention is to provide compensation for an artificially imposed resistive load and not to contribute to the patient’s work-of-breathing.

Note 2 to entry: The assistive offset is typically calculated by the ventilator, based on information entered by the operator, for example, the inside diameter of an endotracheal tube.

Note 3 to entry: The assistive offset is not intended to support the patient's elastic load.

Note 4 to entry: To achieve compensation during the expiratory phase of a breath the airway pressure may be reduced below the baseline airway pressure for part of the expiratory phase but this vocabulary does not sanction the intentional application of sub-ambient pressures to the patient connection port.

4.13.14 lung shorthand name for the connected, respiratory-gas containing cavities within the respiratory system, extending from the surface profile of the face, or from the patient connection port if an airway device is used, through to the alveoli

Note 1 to entry: In the absence of a more suitable term it has become common practice to use this name to identify the respiratory-gas containing parts of the respiratory system identified by this definition. It is inclusive of what is generally referred to as the airway as well as the lobes containing the alveoli. In this simplified model, one, or two, compliant chamber(s) are connected to a patient-connection port connector by means of a pneumatic resistance. This concept has proven to be useful in discussing lung mechanics and as the basis for the pneumatic simulation of the respiratory system by what has become known as a test lung.

Note 2 to entry: This name is not a synonym for the lungs, the clinical name for the pair of organs within the ribcage, which contain the alveoli.

Note 3 to entry: See also lungs (4.13.15).

4.13.15 lungs pair of organs within the ribcage (thorax), connected to the atmosphere by an airway through which, during natural breathing, air is cyclically drawn and then expelled, and which provide gas/blood interfaces that enable oxygen from the air to pass into the blood and carbon dioxide to be removed

4.13.16 respiratory system anatomical system related to breathing including the upper airway, lower airways, lungs, chest wall, pleural space, brainstem respiratory control centre, phrenic nerves, neuromuscular junctions, diaphragm and accessory muscles of ventilation

4.13.17 respiratory system coefficients value of those parameters that affect the work of breathing (for example lung and airway compliance and resistance), but which are not directly affected by a patient's respiratory activity

NOTE1: Although generally treated in respiratory mechanics as having a constant value, respiratory system coefficients vary with volume and flow, as appropriate. They may also vary with time, sometimes rapidly, during a ventilation procedure.

4.13.18 ventilator breathing system VBS anaesthesia breathing system pathways through which gas flows to or from the patient at respiratory pressures, bounded by the port through which respirable gas enters, the patient-connection port and the gas exhaust port

Note 1 to entry: These pathways typically extend within and outside the body of the ventilator, with those outside being operator-detachable.

Note 2 to entry: The port of entry of a respirable gas into the ventilator breathing system may be inside the body of the ventilator and should not be confused with an external connection port into which respirable gas enters before being reduced to respirable pressures.

Note to admitted term: This admitted term is included in this vocabulary for use in reference to the specific class of ventilators that are configured to ventilate patients with an anaesthetic gas mixture. With this application the

definition may be made more specific with ‘respirable gas’ becoming ‘anaesthetic gases and the ‘port through which respirable gas enters’ becoming the ‘fresh-gas inlet’.

[SOURCES: ISO 4135:2001, definitions 3.1.6 and 4.1.1, modified and 80601-2-12:2011, definition 201.3.221, modified]

4.13.19 set prescribed in advance

EXAMPLE 1: A set pressure limit.

EXAMPLE 2: The set inspiratory pressure.

Note 1 to entry: This term is used in this vocabulary as a prefix to distinguish an intended value of a quantity from an actual or measured value of the same quantity. In common usage it is sometimes used as a prefix to such terms as ‘mode’, ‘inflation-type’ or ‘function’ but the word ‘selected’ is considered more appropriate for that purpose.

Note 2 to entry: As a prefix, this term qualifies a term denoting a quantity if this attribution is not clear from the context of use, although such a qualification is unnecessary when the base term is used in the context of ‘settings’, for example, on a labelled key in the ‘settings’ sector of a users’ interface.

Note 3 to entry: A set value may be determined directly or indirectly.

Note 4 to entry: A value is directly set if the operator sets or selects a value that is intended to become the actual value of that quantity, for example, the intended duration of an inspiratory time.

Note 5 to entry: A value is indirectly set if the operator sets or selects a value that:

→ only partially contributes to the actual set value, → sets or selects values of more than one setting, which, together, result in a calculated set value, or → selects an algorithm that determines the setting based on other settings or measurements.

Note 6 to entry: A value may also be set by other means, for example, remotely, as a default setting by the responsible organization, or by accessing a pre-set value.

Note 7 to entry: Examples of set values are the indicated value on a calibrated setting device and the displayed value on a calibrated device that is independent of the setting device.

Note 8 to entry: See also the reference to settings in 4.13.19 and inAnnex G.

4.13.20 measured determined by a measuring device or system

Note 1 to entry: This term is used in this vocabulary as a prefix to distinguish the value of a quantity as determined by a measuring device or system, from an actual value or set value of the same quantity.

Note 2 to entry: Measured values may be displayed or recorded as discrete values or as a continuous waveform.

Note 3 to entry: As a prefix, this term is used to appropriately qualify a term denoting a quantity if this attribution is not clear from the context of use but such a qualification is unnecessary when the base term is used in the context of ‘measured values’, for example, on a labelled display in the ‘measurements’ sector of a user interface or on a continuous trace of measured ventilation parameters.

Note 4 to entry: The value of the quantity being measured may be the direct result of its setting, the composite result of a setting and other influences not being directly regulated, or completely independent of any ventilator settings.

The displayed measured value of a quantity resulting from a setting is sometimes referred to as the ‘set’ value but wherever this is done the distinction is to be maintained.

Note 5 to entry: A displayed or recorded measured value may be a value calculated from the results of more than one measurements of other quantities.

Note 6 to entry: See also Annex G.2.

4.13.21 preset value one of a set of stored configuration parameter(s), including selection of algorithms and initial values for use by algorithms, which affect or modify the performance of the ventilator

Note 1 to entry: Presets are commonly configured by the manufacturer or a responsible organization.

Note 2 to entry: Access to a pre-set value(s) is typically controlled by:

- a tool, - a responsible organization password and a technical description, separate from the instructions for use, - an individual operator password, - voice recognition, or - biometric means.

4.13.22 actual value value of a quantity as it exists in fact

Note 1 to entry: This is the true value of a quantity, which may, or may not, be determinable by a measuring device.

Note 2 to entry: The definitions of terms denoting quantities, in this vocabulary, denote the actual value of that quantity. Set values are the means by which an operator informs the ventilator of the intended actual value and measured values are displays or records of the actual value, to the accuracy and resolution of the measuring system.

4.13.23 limit point or level beyond which the value of a patient parameter may not pass without an action by the ventilator

Note 1 to entry: The action may be a notification or the implementation of means to prevent or mitigate a hazardous situation.

Note 2 to entry: In this Vocabulary this term is restricted to the designation of safety constraints that provide patient protection that is completely independent of the controlled ventilation parameters.

Note 3 to entry: An alarm system uses an alarm limit in determining an alarm condition.

Note 4 to entry: See also safety limits and alarm terminology (4.12).

4.13.24 normal use operation, including routine inspection and adjustments by any operator, and stand-by, according to the instructions for use

Note 1 to entry: Normal use should not be confused with intended use. While both include the concept of use as intended by the manufacturer, intended use focuses on the medical purpose while normal use incorporates not only the medical purpose, but maintenance, service, transport, etc. as well.

[SOURCE: IEC 60601-1:2005, definition 3.71]

4.13.25 intended use intended purpose use of a product, process or service in accordance with the specifications, instructions and information provided by the manufacturer

Note 1 to entry: Intended use should not be confused with normal use. While both include the concept of use as intended by the manufacturer, intended use focuses on the medical purpose while normal use incorporates not only the medical purpose, but maintenance, service, transport, etc. as well.

[ISO 14971:2000, definition 2.5]

4.13.26 normal condition condition in which all means provided for protection against hazards are intact

[SOURCE: IEC 60601-1:2005, definition 3.70]

4.13.27 single fault condition condition in which a single means for reducing a risk is defective or a single abnormal condition is present

[SOURCE: IEC 60601-1:2005, definition 3.116]

4.13.28 accompanying document document accompanying medical electrical equipment, a medical electrical system, equipment or an accessory which contains information for the responsible organization or operator, particularly regarding basic safety and essential performance

[SOURCE: IEC 60601-1:2005, definition 3.4, modified]

4.14 Gas Port Terminology

4.14.1 port opening for the passage of a fluid through a specified interface

Note 1 to entry: Typical interfaces where ports occur are

• where gas enters a medical device, • where operator detachable tubing is connected to a medical device and • where a ventilator breathing system is connected to the patient or to an airway device.

Note 2 to entry: A port will be typically, but not necessarily, in the form of a specific connector.

4.14.2 gas intake port port through which a respiratory gas is drawn for use by the patient

Note 1 to entry: For anaesthetic ventilators the respiratory gas is typically the fresh gas from an anaesthetic machine and for blower-based ventilators it will be typically ambient air.

[SOURCE: ISO 80601-2-12, definition 201.3.208 modified]

4.14.3 emergency air intake port dedicated intake port through which ambient air may be drawn when the supply of respiratory gas is insufficient or absent

[SOURCE: ISO 4135:2001, definition 3.2.3 modified]

4.14.4 exhaust port port of the medical electrical equipment or device from which gas is discharged to the atmosphere during normal use, either directly or via an anaesthetic gas scavenging system.

[SOURCE: ISO 80601-2-12, definition 201.3.205 modified]

4.14.5 gas output port port of the medical electrical equipment or device through which gas is delivered at respiratory pressures to an operator-detachable part of the ventilator breathing system

[SOURCE: ISO 4135:2001, definition 3.2.8 modified]

4.14.6 gas return port port of the medical electrical equipment or device through which gas is returned at respiratory pressures through an operator-detachable part of the ventilator breathing system, from the patient-connection port

[SOURCE: ISO 80601-2-12, definition 201.3.210 modified]

4.14.7 gas input port port to which gas is supplied under pressure

Note 1 to entry: Gas input ports may be labelled as for inflating gas, driving gas, high-pressure gas or low-pressure gas.

[SOURCE: ISO 4135:2001, definition 3.2.10 modified]

4.14.8 patient-connection port patient connection port of a me equipment or device intended for connection to the patient or to an airway device

Note 1 to entry: The patient-connection port is generally part of the ventilator breathing system and is at the end proximal to the patient.

Note 2 to entry: Although patient-connection port is the correct formal term as used in ISO ventilator standards it is unnecessarily long for general use and the abbreviated term patient connection is adequate for use in that context.

Note 3 to entry: Particular standards invariably specify that the patient-connection port is required to be in the form of a specific standardised connector(s), for example, one or more connectors conforming to ISO 5356.

Note 4 to entry: In ventilators designed to provide non-invasive ventilation (NIV) and where the ventilation function is dependent upon a design feature of a component that connects the ventilator to the patient’s airway, then the patient-

connection port becomes the contact line of the seal to the patient’s face and there is no patient-connection-port connector.

Note 5 to entry: See also non-invasive ventilation (4.13.12).

[SOURCE: ISO 80601-2-12:2011, definition 201.3.218 modified]

Annex A (Informative)

Rationale and Guidance

A.1 General guidance

This Annex provides rationale for the important clauses of this document and is intended for those who are familiar with the subject of this document but who have not participated in its development. An understanding of the reasons for the main requirements is considered to be essential for its proper application. Furthermore, as clinical practice and technology change, it is believed that rationale for the present requirements will facilitate any revision of this document necessitated by those developments.

The clauses and sub-clauses in this annex have been so numbered to correspond to the clauses and subclauses in this International Standard to which they refer. The numbering is, therefore, not consecutive.

A.2 Rationale for particular clauses and sub-clauses

Rationales for particular sub-clauses of Clause 4

The numbering of the following rationales corresponds to the numbering of the clauses in this document. The numbering is, therefore, not consecutive.

Sub-clause 4.4 Rate terminology

The ventilation rate terms in this sub-clause have been grouped into two further sub-clauses. The first of these groups comprises the terms that are commonly used on ventilator user interfaces.

The second group comprises those that may be required for specific purposes such as in technical descriptions, clinical papers or data logging. The purpose of listing and defining them is to ensure that, when used, they are always denoted by the same term.

As with other terms in this vocabulary, the purpose of these rate terms is solely to provide standardised terms to reference to each of a range of related particular concepts. There is no implied requirement that manufacturers should make use of every one of these terms in the instructions for use and descriptions of their ventilation equipment.

Sub-clause 4.8 Mode terminology

The Introduction summarises the factors that led to a comprehensive review of the vocabulary of artificial ventilation and the preparation of this International Standard. A key term in the review was that of ventilation mode because the concepts behind it are fundamental to the structure of the terminology presented in this vocabulary. An explanation of how the definitions associated with it were derived is, therefore, an essential background to understanding that structure.

Early devices for delivering automatic ventilation by means of intermittent positive pressure, operated to a fixed cyclical pattern with a range of settings for just the basic parameters. As new devices were developed additional ventilation patterns became available and these were proposed and offered as selectable modes of operation. In order that specific modes could be easily identified for selection in order to provide particular treatments these modes were given names or acronyms.

However, with the increasing flexibility offered by electronic control systems, more and more permutations and combinations of the basic elements of gas delivery were devised – to the point where it was no longer practical to provide every set pattern with a unique name. Today, nearly 100 different names and approaching 30 mutually exclusive modes make it impossible to teach, comprehensively, which mode to use in which clinical situation. Consequently, most users have only been taught just a limited range of these modes and it has become very difficult for them to relate different manufacturers’ modes to each other – a problem compounded by a lack of consistency in the terminology used to describe them.

A simple analysis of the structure of these modes reveals that they all require the selection of both the regulated parameter used to inflate the lungs and a pattern that determines when inflations occur; functions that can be conveniently referred to as the inflation-type and the ventilation pattern. It also becomes clear that, conceptually and from a clinical perspective, in most cases the choice of inflation-type is largely independent of the choice of ventilation pattern.

In the vocabulary of this International Standard, this concept has been formalised with the ventilation mode becoming a composite of two independent, operator-selectable elements, classified as a mode pattern and an inflation-type, with the inflation-type determining how the airway pressure and flow will be regulated during an inflation, once initiated, and the ventilation pattern determining how the ventilator will respond to patient-trigger events and what and when it will cause to be delivered irrespective of any patient actions.

This is a logical step because most of the clinically distinctive characteristics of the classical modes that still form the foundation of modern ventilation modes are those that relate to the time-pattern of interactive events between the ventilator and the patient, and which are largely independent of the delivery-regulation means.

In practice, many manufacturers have already, at least partially, informally introduced such a separation in the manner in which they have labelled their ventilator control panels and structured their instructions for use.

From this perspective, it is pertinent to note that part of the confusion with respect to ventilation modes resulted from manufacturers labelling their modes with names that feature just one of these attributes; some modes may be labelled SIMV - a ventilation pattern, and others VCV – an inflation-type. In accordance with this vocabulary both of these mode labels would be incomplete; the correct mode designation requires both an indication of the ventilation pattern and the set inflation-types; the examples would be, SIMV-PC or SIMV-VC and CMV-VC.

The above approach reduces the number of pre-coordinated names required significantly as any of a number of inflation-types can be independently selected for use with each ventilation pattern - instead of N*M different mode names to learn there become just M ventilation patterns plus N

inflation-types. Ventilator operation can therefore be described as if made up from elements of a construction set. As an example, it enabled a list of 58 mode names, taken from manufacturers’ literature, to be reduced to just 8 ventilation patterns and 8 inflation-types – each of which can be placed into one of an even smaller number of easily remembered groups.

This format focuses on the pattern to which inflations are initiated and of the type of inflation that is delivered, irrespective of which ventilation-pattern and inflation-type combination can be used with which setting, and for which clinical intention. Not only is the number reduced but the structured format of these names improves ventilator usability that is much easier to teach, recognise, learn and remember.

With this perception of what constitutes a ventilation mode in current practice, in order to understand how modes relate to each other, it is necessary to create a classification system that groups them in terms of what they have in common and in what way they differ. It is considered that present trends are likely to increase this disconnection between a functional classification of ventilation patterns and clinical intention and that the only viable option is to base mode classifications on function alone. When this is done, only three groupings are required. Teaching can then be in terms of the common characteristics of, and mutual differences between, the ventilation patterns in each group, and the appropriate settings for each of these ventilation patterns for different clinical intentions. Additionally, with only 3 or 4 basic families of inflation- types the instructions can be centred on the clinical considerations of the alternative methods of inflation and of its termination. Most of this will be independent of the ventilation pattern with which it will be used but some instruction will be necessary where the selected inflation-type may affect the clinical intention of the resultant ventilation modes. Although, conceptually, around 20 standardised types of inflation could be made available for operator selection with each ventilation pattern, in practice manufacturers will only offer the much more limited range of combinations likely to be most used in clinical practice.

When viewed in this way it can be seen that, in the past, many ‘new’ modes that have been introduced, with their own proprietary names, have in fact been nothing more than an easily described sub-set of a standard inflation-type.

However, users will always be looking to use shorthand names in the day-to-day operation of ventilators and this need is addressed in this vocabulary, as far as possible, by retaining commonly used names as standardising generic ventilation-pattern and inflation-type names; although using each one with its own standard definition. This will enable users to be able to operate current ventilators the same as at present. The difference is that the named ventilation patterns and inflation-types are classified into the main groups so those users interested in the differences between modes will find that these are always explained from the same reference points. These classifications also form the basis of the framework for the unique identification by name and code for any mode within the scope of this vocabulary.

A further question may be as to where the trigger function for patient initiation fits into these classifications. In some previous classification proposals, in which initiation is considered to be a property of the inflation-type, the triggering-function was also included in these properties. In the classification system of this vocabulary the initiation of an inflation is a property of the ventilation pattern. However, a ventilation pattern is just a set of rules defining how the ventilator responds

to various inputs. Logically, therefore, the ventilation pattern is simply responding to a signal from a ventilator detection function indicating that the measurement of a patient parameter(s) has passed a set threshold value. With this concept, the trigger function becomes just another ventilation monitoring function that provides a signal to the ventilator control system. In practice, most major manufacturers treat patient-triggering in this way - as an independently-selectable, settable monitoring function to provide a signal when the monitored parameter reaches a set level, as may be required by the selected ventilation pattern algorithm.

Sub-clause 4.8.4 - ventilation-mode groups

Mode groups have been introduced solely to provide a means of classifying modes to assist with the understanding and teaching of how the large numbers of modes currently in use are related to each other. There is no requirement for manufacturers to include reference to these groups in product labelling but where used it is required to be in accordance with this International Standard.

In this International Standard four mode groups have been specified; three based on ventilation patterns and one comprised of named modes that relate, in particular, to supervisory and ancillary functions. The defining characteristics of each of these groups are given in entry 4.8.4 ventilation- mode groups.

Sub-clause 4.8.5 - assured ventilation

The admitted term, mandatory ventilation, is included in this International Standard because it has become firmly established over several decades by its use in the mode names of CMV, IMV and SIMV. In the early implementations of these modes both the initiation and the delivery was imposed on the patient but with the modern approach to ventilation, which allows the patient to contribute to their own ventilation as much as they are able, the term only makes sense when used to convey the concept of the assured initiation of a selected inflation. This is the only sense in which it is used in this International Standard. However, because the word mandatory is ambiguous when used as a term in this context, in that it can allow the term to be taken to mean either of these, and because this has allowed it to be used to give the appearance of unifying a range of different concepts, the word is only used in the vocabulary in this International Standard in reference to the traditional mode patterns that have it incorporated into their name. For other purposes, natural language phrases such as ‘assured to be’ are used to convey the defined concept wherever possible, in preference to the term mandatory or its inflected forms.

In the related semantics, the delivery of a mandatory-inflation causes mandatory ventilation of the patient’s lungs but only in the sense that the selected type of inflation is assured to be initiated; not that the inflation-type, in itself, will necessarily deliver an assured volume. It follows that the term mandatory minute volume is the sum of the tidal volumes per minute that are due to mandatorily initiated primary inflations. This may be less than the set minute volume although the total minute volume will never be less than that set.

Sub-clause 4.8.13 - APRV (airway pressure release ventilation)

The rational for the introduction of this mode and its name was to allow patients with acute oxygenation failure to breathe with better coordination, improved gas exchange and less

barotrauma. The periodic release and near immediate subsequent build-up of airway pressure was intended to assist the patient's own breathing efforts while not allowing the lungs to collapse.

Although that rational describes the essential concept of APRV it is recognised that, with this mode selected, many manufacturers now permit the operator to set the BAP phase time (tL) to values far in excess of any expected exhalation flow times. The justification for this is that the ongoing treatment of a patient requiring APRV during the initial acute period may well involve the progressive adjustment of the two BAP levels and also the two phase times, both as individual values and their differentials, in order to provide a step-less continuity of treatment - working towards a single, reducing, level of CPAP, without the discontinuity involved in changing over to a different mode.

Annex B (Informative) not used

Annex C Illustrations of Ventilation Terms (Informative)

An important aspect identified in the development of the vocabulary of this International Standard is that part of the present confusion in the use of ventilation terminology is the lack of distinction between the setting perspective and the outcome perspective.

Most representations of ventilation patterns and inflations are based on typical waveforms as seen on user interface displays, which is inevitably an outcome perspective. This is a helpful approach when describing the interpretation of the function of a specific ventilator but inevitably such a display introduces indeterminate artefacts and these can detract from the clarity of a formal diagrammatical representation of the changes of state that are actually set to occur.

In particular, although set flow changes can be made to occur almost instantaneously this is not possible with pressure changes because of the impedance characteristics of a patient’s respiratory system. With such changes at the initiation and termination of an inflation where, conceptually, the set value makes a step change, in practice, the responses of pressure-regulator functions have to be suitably restrained to set rise times in order to avoid excessive overshoots and subsequent oscillations.

With this perspective, and as appropriate, diagrammatic representations of settings are shown without artefacts whereas those of typical outcomes include them. The examples shown in Figure C.1 illustrate typical differences, highlighted by the use of the colour coding employed in other diagrams in this International Standard, with blue representing set parameters and green representing outcomes.

Additionally, some of the figures in this Annex illustrate the waveforms that result when unusual settings are used with named ventilation patterns; although these settings are within the range available for such modes on currently manufactured ventilators.

These unusual waveforms are not shown with any intention of advocating the use of such settings for a particular treatment, but to demonstrate how actual waveforms can be very different from those normally provided to illustrate a mode function. Such illustrations highlight that the ventilation waveforms that can be generated with a specific classical pattern-based mode, but with unusual settings, are not necessarily all unique and some may overlap those that can be generated with another of the classical patterns.

1 Airway pressure, pAW

3 Inspiratory pressure, 2 Ambient 4 BAP 5 PEEP pressure

Flow-regulated 6 Inspiratory time, tI Inflations 7 Inspiratory flow 9 Inspiratory flow

10 Expiratory- flow time 8 Expiratory 11 flow Expiratory flow waveform

1 Airway 12 pressure, Rise time pAW 13 Inspiratory pressure

2 Ambient 4 BAP 5 PEEP pressure

6 Inspiratory time, tI (PC), (PS) Pressure-regulated Inflations

14 7 Peak Inspiratory inspiratory flow flow

8 Expiratory flow

Figure C.1 —Format used in this International Standard for representations of ventilation patterns and inflation-types

Inspiratory-pressure: 3 Waveform 4 Instantaneous 2 Rise time Expiratory-pressure: 9 Waveform 10 Instantaneous 5 Inspiratory 1 Airway 7 pressure 6 Peak Δ Inspiratory pressure inspiratory pAW pressure pressure 8 End inspiratory pressure

22 Baseline airway pressure 21 12 PEEP 11BAP Ambient pressure

13 Inspiratory time

Key to colour scheme: 14 Set value Inspiratory Measured value flow

16 Peak inspiratory flow

20 Expiratory flow time

17 Inspiratory flow time

18 Expiratory-flow 15 19 Peak waveform Expiratory expiratory flow flow

(a) Typical airway pressure and flow waveforms for a pressure-control inflation

Figure C.2 (1 of 5) — Illustrations of the application of defined ventilation terms in designating key features of typical inflation waveforms

Inspiratory-pressure: 4 Waveform 5 Instantaneous 3 Rise time Expiratory-pressure: 2 Inspiratory 9 Waveform 10 Instantaneous 1 pressure 6 Peak Airway inspiratory pressure, pressure 7 Δ Inspiratory pAW pressure 8 End 22 Baseline airway inspiratory pressure 12 PEEP 11 BAP pressure 23 Ambient pressure

Key to colour scheme: Set value Measured value

13 Inspiratory flow 15 Peak 16 Termination inspiratory flow flow

17 Inspiratory time 20 Expiratory flow time

(b) Typical airway pressure and flow waveforms for a pressure-support inflation

Figure C.2 (2 of 5) —Illustrations of the application of ventilation terms in designating key features of typical inflation waveforms

2 Rise time 1 Airway pressure, pAW 3 5 High Inspiratory 4 pressure pressure Δ Inspiratory termination pressure limit

6 PEEP 7 BAP 14 Ambient pressure

8 Key to colour scheme: Inspiratory Set value flow Measured value 10 Peak inspiratory flow

0 12 Peak 11 Inspiratory time expiratory flow

Figure C.2 (3 of 5) — Illustrations of the application of ventilation terms in designating key features of typical inflation waveforms

2 Inspiratory-pressure waveform 1 Airway pressure, pAW 3 Expiratory-pressure: Plateau pressure 4 Waveform 5 Instantaneous 8 Peak inspiratory 7 pressure Inspiratory pressure 20 Baseline airway pressure 6 PEEP 9 BAP 21 Ambient pressure

10 Inspiratory time

12 Rise time (if applicable) Key to colour scheme: 11 Set value Inspiratory Measured value flow 14 Inspiratory 13 pause time Inspiratory flow 19 Expiratory flow time

16 Inspiratory flow time

15 Expiratory 17 Peak flow expiratory 18 flow Expiratory-flow (waveform)

(d) Typical airway pressure and flow waveforms for volume-control inflation with an inspiratory pause

Figure C.2 (4 of 5) —Illustrations of the application of ventilation terms in designating key features of typical inflation waveforms

2 Inspiratory-pressure (waveform)

4 Pressure 1 Airway limit pressure, pAW 3 Peak inspiratory pressure

14 Baseline airway pressure 5 PEEP 6 BAP 15 Ambient pressure

10 Inspiratory time

7 Rise time 11 Inspiratory (if applicable) flow waveform

8 Key to colour scheme: Inspiratory Set value flow 10 Actual value

Inspiratory flow

13 9 Expiratory-flow Expiratory 12 Peak (waveform) flow expiratory flow

(e) Typical airway pressure and flow waveforms for a pressure-limited volume-control inflation

Figure C.2 (5 of 5) — Illustrations of the application of ventilation terms in designating key features of typical inflation waveforms

1 Airway pressure, 3 pAW Inspiratory pressure

PEEP 2 Ambient 4 5 BAP pressure 6 Inspiratory 7 Expiratory time, tE time, tI

8 Cycle time (1/Rate)

9 Inspiratory flow

10 Expiratory flow

©NSJ

Figure C.3 — Typical airway pressure and flow waveforms for a CMV-PC mode

1 Airway pressure, pAW 3 Inspiratory pressure

2 Ambient 4 PEEP 5 BAP pressure

6 Inspiratory time, 7 Expiratory time, tE tI

8 Cycle time (1/Rate)

11 Primary- inflation 12 Primary expiratory phase phase

13 Primary-inflation cycle

9 14 Inspiratory Inspiratory phase flow

Figure C.4 — Typical airway pressure and flow waveforms for a CMV-VC mode

1 Airway pressure, p 3 Inspiratory pressure AW or BAP-high 2 Ambient 4 PEEP 5 BAP pressure

6 Inspiratory time, tI 7 Expiratory time, tE or BAP-high time, tH or BAP time, tL

8 Cycle time (1/Rate)

9 Primary-inflation phase 10 Primary expiratory phase or BAP-highphase or BAP phase 11 Primary-inflation cycle or Bi-level cycle 12 14 Concurrent Inspiratory 16 Inspiratory breath 15 Inspiratory flow phase phase

Figure C.5 — Typical airway pressure and flow waveforms for a CMV- PC mode set with extended phase times

1 Airway pressure, pAW 3 Inspiratory pressure or BAP-high 2 Ambient 4 PEEP 5 BAP pressure

6 Inspiratory time, tI 7 Expiratory time, tE or BAPH time, tH or BAP time, tL

8 Cycle time (1/Rate)

9 Primary-inflation phase or BAP-high phase 10 Primary expiratory phase or BAP phase

11 Primary-inflation cycle or Bi-level cycle

12 14 Inspiratory phases Inspiratory 15 Concurrent or BAPH phases flow breath

Figure C.6 — Typical airway pressure and flow waveforms for a CMV- PC mode set with an extreme inverse I:E ratio

Note to figures C.5 and C.6: The figures on these pages illustrate unusual settings of this mode which are possible with the range of settings available on currently manufactured ventilators. As explained in the introduction to this Annex (C.1), such illustrations are not shown with the intention of advocating such settings, but to demonstrate how actual waveforms can be very different from those normally provided to illustrate a mode function. Such illustrations highlight that the ventilation waveforms that can be generated with a specific classical ventilator pattern-based mode, but with unusual settings, are not necessarily all unique and some may overlap those that can be generated with another of these modes.

3 Assured delivery 1 Airway pressure, 4 pAW Inspiratory pressure

2 5 PEEP 6 BAP Ambient pressure

7 Inspiratory 8 Expiratory time 9 Cycle time (1/Rate) time, tI 11 Primary expiratory 10 Primary- 11 Primary 10 Primary- phase inflation inflation phase expiratory phase phase

12 Primary-inflation cycle 13 12 Primary-inflation cycle Inspiratory flow

Figure C.7 — Typical airway pressure and flow waveforms for an A/CV - PC mode

1 Airway 17 pressure, End-inspiratory pAW pressure

2 5 PEEP 6 BAP Ambient pressure 8 Expiratory 18 Set period (1/Rate) time 10 Primary- inflation 11 Primary expiratory phase phase

12 Primary-inflation cycle

13 Inspiratory 3 Assured flow delivery 19 Inspiratory flow 0

Figure C.8 — Typical airway pressure and flow waveforms for an A/CV – VC mode

1 Airway pressure, pAW 3 Inspiratory pressure

2 4 BAP 5 PEEP Ambient pressure

6 Inspiratory 7 Expiratory time 8 Set period (1/Rate) time, tI

9 Primary- 9 Primary- inflation 10 Primary expiratory inflation 10 Primary expiratory phase phase phase phase 11 Primary-inflation cycle 11 Primary-inflation cycle

12 Inspiratory 16 Flow- flow trigger level

13 Expiratory flow 14 Unrestricted breath (cycle) below the trigger level. 15 Concurrent unrestricted Inspiration followed by expiration expiration followed by inspiration ©NSJ

Figure C.9 — Typical airway pressure and flow waveforms for an A/CV – PC mode

(No pressure-support inflation-type is permitted with this mode but it could be optionally labelled: Bi-level ventilation (A/CV – PC ).)

3 Support-inflations 4 Primary-inflations 1 Airway pressure, pAW 2 Δ Inspiratory 5 pressure Δ Inspiratory pressure

6 PEEP 7 BAP

9 Inspiratory 10 Expiratory time time 11Inspiratory time, 8 Synchronisation tI 14 Expiratory window 13 Inflation phase 12 Set period (1/Rate) phase 16 Primary- 15 Support-inflation cycle inflation 17 BAP phase phase or Primary expiratory phase

18 Primary-inflation cycle

19 27 Flow-trigger Inspiratory level flow 23 Unassisted-breath

20 25 Expiratory phase Expiratory 24 Inspiratory flow phase 26 Supported-breath cycle ©NSJ 21 Primary 22 Primary expiratory-flow pause time expiratory-flow time

Figure C.10 — Typical airway pressure and flow waveforms for an SIMV- PC\PS mode

5 Primary-inflations 1 Airway h pressure, 4 Δ Inspiratory 6 Support-inflations pAW 3 Δ Inspiratory pressure pressure

2 Inspiratory pressure 7 PEEP 8 BAP

9 Expiratory 12 Inspiratory time, tI 13 BAP time, tL 10 Inflation phase phase 14 Set period (1/Rate)

11 Support-inflation cycle 15 Primary-inflation phase 16 BAP phase

18 17 Primary-inflation cycle Inspiratory flow 22 Flow-trigger level 21 Unassisted-breath

a) with typical settings for the simulation of Bi-level ventilation

Figure C.11 (1 of 4) — Typical airway pressure and flow waveforms for variations on an SIMV- PC\PS\PS mode

1 Airway 2 Primary-inflations

pressure, pAW

3 Inspiratory pressure, pI 4 PEEP 4 PEEP 5BAP

6 Inspiratory time, tI 7 Expiratory time, tE

8 Set period (1/Rate)

9 Primary-inflation phase 10 BAP phase

11 Primary-inflation cycle

12 14 Inflation phase Inspiratory 15 Expiratory

flow phase

b) with typical settings for the simulation of APRV

Figure C.11 (2 of 4) — Typical airway pressure and flow waveforms for variations on an SIMV- PC\PS\PS mode

1 Airway pressure, 3 ΔhInspiratory 4 Δ Inspiratory pAW pressure pressure

BAP-high 2

5 BAP 6 PEEP

7 Synchronisation window (typical) 8 Set period (1/Rate) 8 Set period (1/Rate)

9 Time-high, tH 10 Time-low 9 Time-high, tH 10 Time-low

14 Expiratory 11 BAP-high phase 13 Inflation phase phase 12 BAP phase

16 Primary-inflation cycle 17 15 Support-inflation cycle Inspiratory flow Flow-trigger level

c) with a PC{S} primary inflation-type and optionally labelled as a Bi-level ventilation mode

Figure C.11 (3 of 4) — Typical airway pressure and flow waveforms for variations on an SIMV- PC\PS\PS mode

1 Airway 2 Primary-inflations pressure, pAW

3 BAP-high (or pH)

4 PEEP 4 PEEP 5 BAP (or pL)

6 Time-high, H t 7 Time-low, tL

6 Synchronisation 8 BAP-high phase 9 BAP phase window (typical)

10 Primary-inflation cycle

11 13 Inspiratory phase Inspiratory 14 Expiratory flow phase

d) with a PC[S] primary inflation-type, no pressure-support at BAP level and optionally labelled as intended for APRV (airway pressure release ventilation)

Figure C.11 (4 of 4) — Typical airway pressure and flow waveforms for variations on an SIMV- PC\PS\PS mode

1 Airway pressure, pAW

3 Δ Inspiratory pressure

2 4 PEEP 5 BAP Ambient pressure

7 Expiratory phase 6 Inflation phase

8 Support-inflation cycle

9 Inspiratory flow 11 Expiratory time

Figure C.12 — Typical airway pressure and flow waveforms for a CSV - PS mode

Previous figures have shown waveforms for pressure-control inflation- 1 Airway Pressure type deliveries on a ventilator with an ACAP adjunct, and with illustrative concurrent spontaneous breaths. In practice there could be several concurrent breaths and they could take many forms. On the right are a shown other possible flow waveforms and these raise the question of 3Baseline airway pressure what a breath is in this situation. tI 2 Airway The flow waveform A shows the delivered volume, as a result of the Flow elevated pressure of the inflation a, as the area b. It can be seen that the A b d set inspiratory time greatly exceeds the inspiratory flow time and so there e is an inspiratory flow pause before the delivered volume is expired. The c expired volume is represented by the area c. It is therefore clear that b and c represent the breath resulting from the inflation a, and that d and e represent a concurrent spontaneous breath.

Waveform B shows a spontaneous expiration f before an inspiration g. B g To do this the patient would have to have made an active expiratory effort f but this is a possible occurrence and in this case the forced expiration coupled with the inspiration still constitutes the requirement for a breath. The complete waveform therefore shows the result of the inflation and two concurrent spontaneous breaths.

Waveform C shows the patient’s inspiratory efforts augmenting the delivered volume resulting from the inflation, and subsequently expiring it, h but there is no spontaneous breath because the inspiratory component h C is not independent of the ventilator-imposed component.

Waveform D shows a reflexive expiration during the flow pause following the imposed delivered volume. As in the previous example because k is not associated with a specific inspiration it does not constitute part of a separate, spontaneous breath. D From these examples it can be seen that, a concurrent breath is one in k which an inspiratory flow is detected either following a period with no

Figure C.13 — Characteristics of a concurrent breath

Composite symbol representing the function of the Coloured rectangle representing the inflation-type that has been selected synchronisation window. After an assured instigation at for assured deliveries. The same inflation-type may also be initiated by a the timed interval, determined by the ventilator set rate, patient-trigger event in accordance with the ventilation-pattern. it provides time for the expiration of any previously inspiration but responds immediately to a patient-trigger Red arrow in this symbol represents an assured occurrence and the event by initiating the already assured inflation. clock signifies that this is set to occur at a timed interval from the previous assured occurrence. This timed interval (1/Rate) is determined Coloured rectangle representing the inflation-type that has by the ventilator set rate. been selected for initiation solely in response to a spontaneous occurrence. Symbol representing the delay period that has been named as the ‘synchronisation window’. Arrow used to represent an envisaged pattern of patient- trigger events. They are shown with a broken outline in the Symbol representing the ventilator initiation of the following figures because they represent the setting assured inflation in the absence of any patient-trigger perspective of what ‘could’ happen. event during the preceding synchronisation window.

Figure C.14 (1 of 6) — Ventilation patterns (a) Key to symbols used in b) to f)

1 Airway 2 Representative pressure-control inflation-types pressure 3 Setting Perspective

4 Time 1/Rate 1/Rate 5 1/Rate 1/Rate

6 Function of the ventilation-pattern in initiating inflations

7 Inspiratory 9 Typical consequent Flow Waveform Flow

Figure C.14 (2 of 6) — Ventilation patterns (b) CMV ventilation-pattern

1 Airway pressure 2 Representative pressure-control inflation-types 3 Setting Perspective

4 Time 5 1/Rate 1/Rate 1/Rate 1/Rate 1/Rate 1/Rate 1/Rate

6 Function of the ventilation-pattern in initiating inflations

7 9 Typical consequent Flow Waveform Inspiratory Flow

Figure C.14 (3 of 6) — Ventilation patterns c) Assist/Control ventilation-pattern

1 Airway 2 Representative pressure-control inflation-types pressure 3 Setting Perspective

5 1/Rate 1/Rate 1/Rate

6 Function of the ventilation-pattern in initiating inflations

7 Inspiratory Flow 9 Typical consequent flow waveform

4 Time

Figure C.14 (4 of 6) — Ventilation patterns (d) IMV ventilation-pattern

1 Airway 2 Representative pressure-control inflation-types pressure 3 Setting Perspective

5 1/Rate 1/Rate 1/Rate

6 Function of the ventilation-pattern in initiating inflations

7 Inspiratory 9 Typical consequent flow waveform Flow

4 Time

Figure C.14 (5 of 6) — Ventilation patterns (e) SIMV ventilation-pattern

1 Airway pressure 2 Setting Perspective

3 Time

4 Function of the ventilation-pattern in initiating inflations

5 Inspiratory 7 Typical consequent flow waveform Flow

Figure C.14 (6 of 6) — Ventilation patterns (f) CSV ventilation-pattern

Annex D Classification of Inflation-types and Modes (Normative)

D.1 Classification of Inflation-types

The principle individual terms relating to currently available inflation-types are defined in sub- clause 4.2. However, there is a large number of possible variations of the waveforms that could be adopted for this purpose and Tables D.1a and D.1b have been included in order to demonstrate how both defined inflation-types and known variations are systematically identified and allocated their systematic names. Table D.1c has been included in order to demonstrate the structure of the schematic coding scheme used in this vocabulary; it provides a template for the naming of current and future inflation-types that are not already specifically designated. It also includes examples of systematic codes but for a more complete list see Tables D.1a and D.1b.

The primary classification of possible inflation-types have been based, in accordance with convention, on the two basic ventilation parameters that can be conveniently regulated - pressure and flow – along with a hierarchy of letters used to codify how an inflation will be managed - after initiation.

The core element of the coding is a pair of capital letters that have been universally adopted in current ventilation terminology and which are defined in sub-clause 4.2, namely, VC, PC, and PS. In this vocabulary, these pairs, each in isolation, represent an inflation-type that, once initiated in accordance with the selected ventilation-pattern, regulate the delivered flow or pressure to the set value until terminated by time, flow, pressure or volume criteria.

Variations from these specific conditions are designated by the attachment, to the base pair, of leading lower case letters and contained trailing letters - the containment being by means of round brackets for termination parameters, curly brackets for conditional termination means and square brackets for additional regulation parameters.

Leading lower case letters are used to indicate features that provide additional functionality to the basic control. These can be either specific to the particular control to which it is attached, in which case it is in italics, or of more general application. An examples of the latter are the letters vt (volume-targeted), which are applicable to PC and PS inflation-types and indicate that the set inspiratory pressure is automatically adjusted, typically inflation-to-inflation, in order to get closer to achieving the set tidal volume with the next inflation.

In these classifications, where the primary means of inflation termination is shown to be other than by time, safety considerations dictate that there will always be some sort of ultimate time limit on every automatically delivered inflation. This may be a factory-set default or an operator- settable value with a limit on the maximum setting but such secondary time limits are not included in the coding so as to keep them as brief as possible.

Allowance has also been made to accommodate the possibility of switching between regulated parameters during an inflation phase.

In this vocabulary, inflation-type systematic codes are used as symbols, as PC, VC and PS are used at present, with the spoken form being either the spoken abbreviation or the full name that has been abbreviated as written in bold type in the following headings. The term descriptions are related to the lines in Tables D.1a and D.1b, as well as those in Table D.1c, by means of the allocated reference number (Ref #). The descriptive notes against the following headings give further information on the specific inflation-types identified by their Ref #:

Refs # 1a – 1f: volume-control; inflation-types that are all flow-regulated to a constant value (or a specified declining-flow pattern) and time-terminated, which, by convention, have been identified under their more generally applicable name of volume-control, with the abbreviation, VC. There are various ways of achieving a required tidal volume within these restraints and most of these are separately referenced by one of the trailing letters, a – f. In practical use, the differences are typically incidental to most operators, and will be evident from the method by which the volume is set. For this reason, as is current practice, for general use all of these alternative possibilities retain the label, VC. However, the specific characteristics that identify the differences in this vocabulary should be always described in the operator’s Instructions for Use (IFU).

Inflation-types that are flow-regulated to a constantly declining value and time terminated, which, by convention, have also been identified under their more generally applicable name of volume- control, with the abbreviation, VC, are identified with the prefix df or cdf.

All volume control inflations delivering leak compensated volumes are identified with the suffix LC.

The attachment of suffixes or prefixes is not generally necessary if the selection of the represented function is otherwise indicated in associated text or by an indicator on the user interface.

Refs # 2 & 3: volume-targeted; inflation-types, which unlike VC, do not control the delivered volume directly but which target a set volume by adjusting the inspiratory settings of a pressure- regulated inflation, typically inflation-to-inflation, depending on measurements of previous deliveries.

Ref # 4: pressure-limited volume-control; a variant of VC in which, when the inspiratory pressure attains a set level during normal operation, excess regulated flow is spilt to atmosphere if necessary to avoid the inspiratory pressure exceeding the set level, resulting in a possibly un- quantified loss of the delivered volume. This variant is indicated by the addition of the trailing code {pLIM}. As this loss is part of the normal operation of this inflation-type an alarm condition is not generated, but if there is any loss of delivered tidal volume patient safety considerations dictate that it should be indicated. If the pressure is limited by pressure-regulation then the code becomes VC→PC (see 4.2.5).

Ref # 5: pressure-control; an inflation-type that, after an initial rise time, is pressure-regulated to a constant value and time-terminated. By convention, it has been identified with the name pressure-control, with the abbreviation, PC.

Ref # 6: pressure support or flow-terminated pressure-control; a pressure control (PC) inflation- type that is intended to be terminated by patient respiratory activity reducing the flow to a set flow level before the set time termination, and which is only used with ventilation-patterns in

which it can only be initiated by a patient-trigger event, has become identified with the name pressure-support, with the abbreviation, PS. If used in a mode pattern in which it may be time- initiated its code reverts to that of a variant of PC, that is, PC{q}.

Ref # 7: spontaneous/timed; a PC inflation-type that is terminated by time if time-initiated, but which is terminated by flow if initiated by a patient-trigger event occurring before the set time, is identified as a conditional variant of PC, i.e., PC{q/t}. This inflation type has become associated with a ventilation mode which is commonly referred to as an S/T mode. As an S/T mode is dependent on this inflation-type, and as the systematic name is too complicated when spoken, S/T has been adopted as the common name for this inflation-type in this vocabulary on the basis that the termination is conditional on whether the initiation is due to a spontaneous breath or a set time. It is typically used in an assist/control ventilation pattern, in which case the systematic mode designation becomes A/CV-S/T (see Table D.2a).

Ref # 8: volume-assisted pressure-support; a PS inflation-type that is extended by the maintenance of the termination flow if the delivered volume has not by then attained the set minimum value. It’s abbreviated systematic designation is PC→VC, with the common name, VAPS.

Ref # 9: pressure-control with ACAP or ACAPH; conceptually, this is a PC primary-inflation with a separately provided ACAP ventilation-pattern adjunct that is active at the inspiratory pressure baseline level (BAPH), which enables concurrent expirations in addition to unrestricted inspirations.

Ref #10: - - synchronised-termination; an inflation-type, intended for use with ACAP or ACAPH adjuncts, where the patient may expire spontaneously during the set inflation phase without terminating the delivery. It then uses a synchronisation window to modulate the actual termination point of each inflation to coincide with the patient’s expiratory activity (see 4.10.7 and 4.10.8). The presence of this feature is indicated by the conditional-termination variation trailing code {S}, spoken as ‘pressure-control with synchronised-termination’.

Ref # 11: flow-regulated, pressure-limited; an inflation type with no specific name but which is typically used in basic paediatric ventilators, where the system is referred to as a T-piece occluder. A set regulated flow is fed to one port of a T-piece and another is periodically occluded either manually by a thumb, or by a timed mechanical occluder. The required pressure is maintained by a variable relief valve.

Refs # 12 - 14: proportional effort support; a variant of a PS inflation-type that is pressure- regulated to a non-constant waveform that is dependent upon the instantaneous value of a patient variable(s) that indicates the patient effort at that point in time, with the intention of providing support to the breathing that is always proportion to the patient’s effort. The variables used are typically either those relating to the loads imposed by airway resistance and the lung stiffness or the neural signals that determine respiratory effort. The concept is identified with the name proportional effort support, with the abbreviation, pES. The full systematic name for a proportional effort support inflation-type will include a reference to which of these indicators of specific patient efforts are supported, i.e., increase in lung volume [v], flow [q], increase in lung volume and flow [q.v], or the electromyographic activity of the diaphragm and intercostal muscles [EMG].

There is currently no agreed name to designate these following, additional regulation parameters, other than the use of a verbal description.

The following references relate to entries in Table D.1c only:

Ref # 15: flow-regulated, pressure-terminated; a flow-regulated inflation that is pressure terminated and with which, as a consequence, there is no direct correlation between the setting and the volume delivered. It is not, therefore, a variant of VC and is classified as a flow-regulated, pressure-terminated inflation-type. This inflation-type is not currently used in mainstream ventilators but is still sometimes used in low-cost, gas-powered resuscitators. These devices are commonly known as pressure-cycled resuscitators on the basis that each phase change is initiated when a measured pressure reaches a set level.

Ref # 16: volume-terminated, pressure-control; this code represents a variant of a PC inflation- type in which the inflation is terminated after a set volume has been delivered. As a variant it is coded as PC(v).

Ref # 17: dual-control; these codes represent hybrid inflations that start with the first inflation- type but under specified conditions may be changed to an alternative type during the course of the delivery. These changes may be bi-directional or unidirectional as indicated by the coupling arrows.

Operator’s primary Regulated Coded form of full Primary Secondary intent parameter Secondary intent(s) Consequent requirements systematic name Ref # classification classification Set parameters Time termination See Table D.1b for options for consequent requirements FR(t ) which becomes VC 1a - 1d VC At least two of: delivered volume, Flow Deliver a specified Constant flow at set value Time becomes dependent variable FR(v ) which becomes VC VC inspiratory flow and inspiratory time volume through the 1e patient connection Time termination If inspiratory pressure is adjusted inflation-to-inflation the vtPC 2 vtPC Tidal volume and inspiratory time port outcome is volume targetted not VC Pressure Flow termination of a pressure- If inspiratory pressure is adjusted inflation-to-inflation the vtPS 3 vtPS Tidal volume and end-flow support inflation outcome is volume targetted not VC

Deliver a specified Pressure limit VC[p Lim] 4 FC [p Lim] Inspiratory flow & time and pressure flowrate through the limit Flow patient connection Time termination FR(t ) which becomes VC 1f VC Delivered flow and inspiratory time port

Deliver a specified Time termination See Table D.1b for options for consequent requirements VC VC Ref VC LC Flow LC Tidal volume and inspiratory time volume to the trachea #/LC

Time termination PC 5 PC Inspiratory pressure and time Flow termination PC(q ) or PS 6 PS PS (2nd setting, Inspiratory pressure and end-flow where appliacble) Flow or time terminated Inflation is flow terminated if patient-triggered and time PC(q/t) which becomes 7 S/T Inspiratory pressure and time, and terminated if time initiated S/T end-flow Pressure Deliver a specified Assured minimum volume Inspiratory time is extended PCVC which becomes 8 PCVC Inspiratory pressur and flow, and inflation pressure VAPS delivered volume Facilitate concurrent expiration Provision of either ACAP or, at least, ACAPH as mode adjunct PC 9 PC Inspiratory pressure and time

Facilitate concurrent expiration Provision of either ACAP or, at least, ACAPH as mode adjunct PC[S] 10 PC [S] Inspiratory pressure and time and flow termination

Flow Pressure limited, time terminated Provision of pressure-limit function FR[p Lim] 11 FR [p Lim] Inspiratory flow and time, and pressure limit Not otherwise specified Parameters determined by settings pES 12 ES Proportion of effort parameter-value Support patient effort Pressure Support as proportion of a Measurement of EMG signals pES[EMG] 13 ES [EMG] to be supported specified patient effort Measurement and intergation of inspiratory flow pES[q.v ], pES[q ] or pES[v ] 14 ES [q.v ], [q or [v ]

Key to abbreviations: VC Volume control t Time Note: The primary and secondary classifications, and the set PC Pressure control p Airway pressure parameters, are what will typically be presented as separate selections VS Volume support q/t Conditional, flow or time termination on the user interface. FC Flow control q Inspiratory flow vt Volume targetted v Cumulated delivered flow

LC Leak compensated p LIM Pressure-limited pES Proportional effort support ACAP Assured constant airway pressure EMG Electromyography dr Declining-ramp flow pattern S Synchronised cdf Concave descending-flow pattern  2016 NSJ

Table D.1a —Inflation-type

Secondary Operator’s Regulated Abreviated form of Primary classification(s primary intent parameter Secondary intent(s) Consequent requirements full systematic name Ref # classification ) Set parameters Time termination; Constant flow Set constant-flow is automatically offset to compensate for VC VC 1a repeatable deviations due to, e.g., flow rise time & back Time termination; Set constant Flow may be set to less than necessary to achieve volume in VC VC 1b At least two of: Deliver a set flow set time, thereby providing an inspiratory pause. delivered or volume to a Time termination; Substantially Continuous intra-inflation correction of set flow so as to VC VC 1c inspiratory volume, specified part of Flow constant flow achieve delivered volume in set time delivered or the ventilator Constant flow at set value Time becomes dependent variable VC 1d VC inspiratory flow, or breathing system drVC VC Ref VC dr Time terminated; Descending- inspiratory time ramp flow pattern #/dr Time terminated; Concave cdfVC VC Ref VC cdf decreasing-flow pattern #/cdf

Time termination Delivered flow is substantially constant and compensated for VC Ref VC LC

measured leak and other deviations VCLC #/lc Deliver a set Time terminated; Descending- Delivered flow is to a descending-ramp flow pattern and VC Ref VC dr; LC Tidal volume and volume to the Flow ramp flow pattern compensated for measured leak and other deviations drVCLC #/lc inspiratory time trachea Time terminated; Concave Delivered flow is to a concave decreasing-flow pattern and VC ref VC cdf; LC

decreasing-flow pattern compensated for measured leak and other deviations cdfVCLC #/lc  2016 NSJ

Table D.1b —Coding Scheme for variants of Volume Control inflation-types

Flow-regulation See See Inflation-type code: variation designators Group Ref Pressure-regulation Group Ref *  * Inflation-type that conditionally interchanges Means of Time FR(t ) becomes VC #1 PR(t ) becomes PC #5 with characteristics of second inflation type Termination Flow Not applicable PR(q ) becomes PS or PC(q ) #6 Pressure FR(p ) #15 N.A Trailing codes Volume FR(v ) becomes VC #1 PR(v) becomes PC(v) #16 (*) Parameter used for termination Conditional Not applicable PR{q /t } becomes S/T #7 {*} Conditional variation on termination means [*] Additional regulation parameters Key for trailing codes: Variation on Synchronised Not applicable {S}; #10 t Time Termination e.g., PC{S} p Pressure v Volume that has been added to lung Variation on q Flow Regulation q/t Flow or pressure, depending on means of Proportional Not applicable pPS becomes pES #12 initiation EMG Electromyographic activity of the diaphragm Dual-control VC PS, VCPC #17 PCVC #17 and intercostal muscles

p Lim Pressure limit [q &v], [q ], [v], [EMG]; #12 Additional factors VC{p Lim} #4 e.g., pES[EMG] - 14 Prefix codes Lower-case Variation on general inflation algorithms, Variation on Volume-targeted Not applicable vt; #2 e.g., vt, pES Algorithm e.g., vtPC & 3 Key for prefix codes: General Notes: vt Volume targeted All Inflations are required by device standards to be pressure-limited, or pressure- terminated, at an independent, operator-set, safe-pressure limit for the patient. Inflations that are not time-terminated are taken to be also time-limited, whether operator-  2016 NSJ settable or not.

Table D.1c — Systematic coding scheme for Inflation-types

ISO/DIS 19223:2016(E)

D.2 Classification of Ventilation-modes

The principle individual terms relating to currently available ventilation-modes and how these are combined to arrive at a systematic name and code are defined and explained in sub-clause 4.8. The rationale to sub-clause 4.8 gives further explanation. Table D.2 has been included in this International Standard in order to provide an illustration of how these individual concepts are combined to provide a scheme that enables the large number of possible ventilation-modes to be individually named and systematically identified.

The primary classification is the mode grouping as defined in 4.8.4, with 3 basic groups, each of which is then broken down into 2 further sub-groups. These groupings are determined solely by the ventilation-pattern as defined in sub-clause 4.8.3. As made clear in the entries to 4.8, the use of these groups is not a necessary condition for conformance with this International Standard but such use does provide a helpful primary classification.

Each row in Table D.2 represents a specific ventilation mode. The two left hand columns serve to segregate these examples into the ventilation mode Groups.

In order to create a mode it is necessary to combine a ventilation-patterns with one or more appropriate inflation-types, the major systematic classifications of which are described in sub-clause 4.2 - with more comprehensive details being tabulated in Annex D.1.

If the ventilator is of a construction that provides an ACAP adjunct, this adds a further level of classification.

The third column lists the systematic code for typical examples of possible specific modes within each group. Examples involving all the characteristic ventilation-patterns of each group are included along with typically associated inflation-types but, as is indicated by the number of entries in Tables D.1, the possible combinations of these two features is far greater than shown. However, the intention is to demonstrate the pattern of use, not to include every possibility. The presence of an ACAP adjunct on the ventilator providing the mode is indicated by the use of its acronym within angled brackets as the final entry to the code. Typically, where present, this adjunct will be applicable to all modes available on any specific ventilator, although it may be appropriate to restrict its activity to only one phase of the primary inflations of certain modes, as illustrated in some of the examples.

The fifth column lists the full systematic name of each ventilation mode (although an exception has been made with the acronym ACAP due to presentational restraints). The comparison of these names with the associated systematic code demonstrates the practicality and conciseness achieved with the adoption of the code as the primary means of ventilator-mode identification.

The shaded rows in the systematic code column indicate examples of modes that may be alternatively labelled as ‘bi-level ventilation modes’. The notes in the fourth column indicate examples of modes that may be settable to achieve APRV (airway pressure release ventilation), depending on the range of settings made available.

Group Systematic code Note s Full systematic name CMV-VC Continuous mandatory ventilation w ith volume-control

CMV-VC Continuous mandatory ventilation w ith volume-control and an assured constant airw ay pressure adjunct during the expiratory phase CMV-PC Continuous mandatory ventilation w ith pressure-control Group 1 a CMV-vtPC Continuous mandatory ventilation w ith volume-targeted pressure-control CMV-PC Continuous mandatory ventilation w ith pressure-control and an ACAP adjunct CMV-vtPC Continuous mandatory ventilation w ith volume-targeted pressure-control and an ACAP adjunct Group 1

A/CV-VC Assist/Control ventilation w ith volume-control A/CV-PC Assist/Control ventilation w ith pressure-control A/CV-vtPC Assist/Control ventilation w ith volume-targeted pressure-control Group 1 b A/CV-S/T Assist/Control ventilation w ith support/timed inflation-type A/CV-PC Assist/Control ventilation w ith pressure-control and an ACAP adjunct A/CV-vtPC Assist/Control ventilation w ith volume-targeted pressure-control and an ACAP adjunct

IMV-VC Intermittent mandatory ventilation w ith volume-control

IMV-VC Intermittent mandatory ventilation w ith volume-control and an ACAPL adjunct during the primary expiratory phases IMV-PC\PS Intermittent mandatory ventilation w ith pressure-control and pressure-support IMV-vtPC\PS Intermittent mandatory ventilation w ith volume-targeted pressure-control and pressure-support IMV-PC\PS\PS Intermittent mandatory ventilation w ith pressure-control, tw o levels of pressure-support and an ACAP adjunct

Group 2 a IMV-PC #2 Intermittent mandatory ventilation w ith pressure-control and an ACAPH adjunct during the inflation phases IMV-vtPC\PS Intermittent mandatory ventilation w ith volume-targeted pressure-control, pressure-support and an ACAP adjunct IMV-PC[S]\PS\PS Intermittent mandatory ventilation w ith synchronised-termination pressure-control, tw o levels of pressure-support and an ACAP adjunct IMV-PC[S] #1 Intermittent mandatory ventilation w ith synchronised-termination pressure-control and an ACAP adjunct

IMV-PC[S] #1 Intermittent mandatory ventilation w ith synchronised-termination pressure-control and an ACAPH adjunct during the inflation phases Group 2 IMV-PC\-\PS #2 Intermittent mandatory ventilation w ith pressure-control, and an ACAPH adjunct and pressure-support at the higher pressure level only

SIMV-VC\PS Synchronised intermittent mandatory ventilation w ith volume-control and pressure-support

SIMV-VC Synchronised intermittent mandatory ventilation w ith volume-control and an ACAPL adjunct during the expiratory phases SIMV-PC\PS Synchronised intermittent mandatory ventilation w ith pressure-control and pressure-support SIMV-vtPC\PS Synchronised intermittent mandatory ventilation w ith volume-targeted pressure-control and pressure-support Group 2 b SIMV-PC\PS\PS Synchronised intermittent mandatory ventilation w ith pressure-control, tw o levels of pressure-support and an ACAP adjunct SIMV-PC\-\PS Synchronised intermittent mandatory ventilation w ith pressure-control, an ACAP adjunct and pressure-support at the higher pressure level only SIMV-vtPC\PS Synchronised intermittent mandatory ventilation w ith volume-targeted pressure-control, pressure-support and an ACAP adjunct SIMV-PC[S]\PS Synchronised intermittent mandatory ventilation w ith synchronised termination pressure-control, pressure-support and an ACAP adjunct

CSV-PS Continuous spontaneous ventilation w ith pressure-support Group 3a CSV-p ES Continuous spontaneous ventilation w ith proportional effort-support and an ACAP adjunct Group 3 CSV-vtPS Continuous spontaneous ventilation w ith volume-targeted pressure-support and an ACAP adjunct CPAP Continuous positive airw ay pressure Group 3b CPAP Continuous positive airw ay pressure w ith an ACAP adjunct Note #1 Common implementations of APRV Note #2 The code for possible implementations of APRV  2016 NSJ

Table D.2 — Systematic classification of typical ventilation-modes, with an ACAP adjunct as a third designation

1 Annex E 2 Conceptual Relationships between Ventilator Actions and Inspiratory Breaths 3 (Informative)

4 Explanation of the relationships shown in Figure E.1

5 Figure E.1 is a diagrammatical representation of the patient-ventilator interaction and the relationship 6 between breaths and inflations. The figure demonstrates the relationship between the action of a ventilator 7 and the resulting breath that is provided, taking into account the contribution of the patient’s respiratory 8 activity.

9 In this vocabulary, breaths are defined from the patient perspective. Five types of breath are designated by 10 the type of inspiratory assistance that might be provided by various means of artificial ventilation. These 11 types of breath are - :

12 1. Spontaneously taken while connected to a ventilator but with no form of inspiratory assistance 13 selected 14 2. Initiated by spontaneous respiratory activity but assisted by a support-inflation 15 3. Initiated by spontaneous respiratory activity but assisted by an ‘assist’ primary-inflation 16 4. Initiated by spontaneous respiratory activity within a synchronisation window occurring at assured 17 intervals but assisted by a ‘synchronised’ primary-inflation 18 5. Completely controlled by a ventilator, as determined by its settings

19 The interaction between the patient and the ventilator during inspiratory or inflation phases for each of these 20 types of breath is as illustrated in Figure E.1 and explained as follows:

21 1. Breaths taken by the patient when connected to a ventilator but without assistance from any type of 22 artificial inflation are all classified as unassisted breaths. However, the work of breathing imposed 23 by the ventilator in response to spontaneous breathing activity could vary from that of a near 24 complete blockage to the perception of unrestricted breathing. 25 26 Figure E.1 illustrates how an unassisted breath generates a ‘patient demand’, which is seen as a drop 27 in airway pressure in an attempt to obtain more flow. If the ventilator is designed to accommodate 28 unassisted breaths it will generate sufficient ‘demand flow’ to satisfy the patient’s demands, which 29 will reduce the pressure drop and, thereby, the work of inspiration. If there is no specific provision 30 for the ventilator to provide a demand flow, the patient may be able to draw in ambient air through 31 an emergency intake valve but the breathing is likely to feel restricted. Without such a valve 32 unassisted breathing may be severely impeded. 33 34 Where demand flow is available, it may be provided by meeting the patient’s flow demands by 35 means of a patient-triggered pressure-regulated inflation-type with the inspiratory pressure set to its 36 minimum value of 1 or 2 cmH2O above the baseline pressure level. Alternatively, it may be 37 provided by the provision of ACAP, an adjunct that facilitates unrestricted breathing by the 38 generation of demand flow in proportion to the patient’s demand without a set trigger threshold. 39 See unrestricted breathing (4.1.5), pressure-support (4.2.6) and ACAP (4.9.2). 40

41 2. Depending upon the ventilation mode selected, some of the patient’s respiratory activity that is 42 sufficient to causes a patient-trigger event may initiate a support-inflation that assists that activity to 43 an extent determined by the support inflation-type selected and its settings. This support inflation- 44 type is only used in modes where it can only be initiated by a patient-trigger event and which can be 45 terminated by the patient’s respiratory activity. The resulting breaths are designated as supported 46 breaths and are addition to the set rate. 47 48 3. With an assist/control ventilation (4.8.7) mode selected, any patient’s respiratory activity that is 49 sufficient to causes a patient-trigger event initiates a primary-inflation that assists that activity to an 50 extent determined by the inflation-type selected and its settings. The resulting breaths are 51 designated as assisted breaths. (If the patient fails to initiate a subsequent primary-inflation during 52 the maximum expiratory time assured by the set rate it will be initiated by the ventilator and 53 generate a controlled breath.) 54 55 4. Spontaneous breaths taken during a timed synchronisation window when an IMV or SIMV mode are 56 selected, are designated as synchronised breaths. The synchronisation windows are initiated at a set 57 rate. The primary-inflation is initiated either when a patient-trigger event occurs while the window 58 is open; or if no trigger event is detected, when the synchronisation window closes. The primary- 59 inflations therefore contribute to the patient’s work of breathing by assisting those spontaneous 60 breaths that occur within each synchronisation window while limiting the occurrence of such 61 assistance to no more than at the set rate 62 63 5. With any Group 1 or Group 2 mode selected, in the absence of a patient-trigger event, the operator is 64 assured that the ventilator will deliver the next primary-inflation after the maximum expiratory time 65 that is determined solely by the set rate. These breaths are entirely dependent upon the ventilator’s 66 primary inflation-type and its settings and are therefore designated as controlled breaths. 67

130 © ISO 2016 – All rights reserved Figure . iagram showing the concepts of the relationship betweenISO/ 19223:2016(E) breath and inflation related terms in the vocabulary of this 68 International Standard

Primary inflation Support inflation (Assured Demand delivery) flow Unspecified delivery

Patient trigger Patient trigger event Patient Time event demand

Synchronisation Window Assisted Supported

Synchronised Inspiratory Unassisted Breath Controlled

Outcome Ventilator delivery functions

Assured rate Means of delivery initiation > Assured rate Connections showing the relationship for modes where the patient is able to increase the primary-inflation delivery rate above that set Unscheduled Connections showing the relationship for modes where patient trigger events do not increase the average primary-inflation delivery rate above that set NSJ Iss 6d: 15/11/2015 69 70

71 Figure E.1 — Diagram showing the concepts of the relationship between breath and inflation 72 related terms in the vocabulary of the International Standard

74 Annex F 75 Concepts Relating to Baseline Airway Pressures 76 and PEEP as Used in this Standard 77 (informative)

78 Inherent in the concept of a ventilation-pattern that determines how and when inflations are delivered is the 79 determination of what happens between inflations. Typically there are clinical requirements to ventilate 80 patients with an elevated baseline airway-pressure and this requires the use specific control elements and 81 appropriate algorithms, particularly when provision is made for unrestricted, unassisted breathing, both 82 between, and concurrent with, primary-inflations. Figures F.19 – F.27 illustrate the application of the 83 terminology in this vocabulary that relate to this phase.

84 Figures F.19 – F.22 show the typical expiratory-phase waveforms that could be expected with four specific 85 usage scenarios. These were chosen to illustrate the effects of settings, patient parameters and control 86 algorithms on pressures during, and at the end of, time-terminated expiratory phases. For the purposes of 87 these explanations the figures all use the same basic CMV-PC mode setting.

88 As the pressure at the patient-connection port falls during an expiration, there is an unavoidable dynamic lag 89 in the corresponding rate of fall of the alveolar pressure. This is mainly due to airway-resistance and flow 90 limitation factors. Normally, the effects of this lag will have fully dissipated by the end of the expiratory phase, 91 but with shorter expiratory times or with diseased lungs, the average alveolar pressure may still be above 92 the measured expiratory pressure at the end of the expiratory phase. The amount by which this average 93 alveolar pressure exceeds the measured positive end-expiratory pressure, PEEP, cannot be measured directly 94 but its presence and order of magnitude is commonly ascertained by the use of an expiratory-hold procedure. 95 The airway pressure measurement at the end of this procedure is the average of that of the pressurised gas 96 in the alveoli that has been able to distribute uniformly throughout the lung during the expiratory-hold time, 97 but it may not fully include the contribution of any trapped gas to the true average pressure.

98 Figure F.19 illustrates the normal situation where the alveolar pressure does lag the expiratory pressure 99 while there is expiratory flow but once the expiratory pressure reaches a constant value at the set BAP level 100 and expiratory flow has ceased an expiratory hold procedure would show that the alveolar gas had ceased 101 distributing and that the average pressure of the gas that had distributed, total PEEP, was at the measured 102 PEEP level.

103 Figure F.20 illustrates a typical situation that may occur when ventilating a diseased lung with airflow 104 obstruction and flow limitation. In this case, the expiratory pressure has reached a constant value at the set 105 BAP but the effects of the dynamic lag have not fully dissipated by the end of the expiratory phase. An 106 expiratory hold procedure would show that the alveolar gas had not ceased distributing and that the average 107 pressure of the gas, designated as total PEEP (tPEEP), was greater than the measured PEEP by the amount 108 designated as dynamic PEEP (dPEEP).

109

110 Figure F.21 again illustrates a typical situation that may occur when ventilating a diseased lung with airflow 111 obstruction and flow limitation. However, in this case an expiratory-control algorithm has been used to 112 determine an optimum expiratory pressure waveform on a ventilator with the ability to maintain such a 113 waveform by means of an ACAP or ACAPL adjunct, or an equivalent function. The waveform has been initially 114 taken below the set BAP level in order to discharge gas from the ventilator breathing system and the patient’s 115 upper airways as quickly as possible before bringing it back up to the set level while the pressure in the lower 116 airways is still declining. The effect is to decrease the dynamic lag in the later stages of the expiration and to 117 thereby reduce the dynamic PEEP.

118 Figure F.22 illustrates a typical situation that may occur if the set expiratory time is too short such that there 119 is insufficient time for the gas in the lung to fully discharge before the next inflation is initiated. This is more 120 likely to occur at the higher set rates as may be appropriate for younger patients or if there is excessive 121 resistance in the expiratory limb of the ventilator breathing system. In this case, the measured PEEP does not 122 reach the baseline pressure level leading to an increase in the measured total PEEP. Although it could be said 123 that this portion of total PEEP is also a dynamic factor, it is not included in the dynamic PEEP measurement 124 because, unlike dynamic PEEP, it is unlikely to be a good indicator of lung impairment.

125 The difference between the measured PEEP and the set BAP is designated in this vocabulary by the term 126 ΔPEEP. Typically there will be no difference between PEEP and the set BAP, but where a difference arises 127 the operator should be aware of the possible implications. A positive difference may indicate too short an 128 expiration time or a restriction in the expiratory pathway of the ventilator breathing system (for example, a 129 contaminated filter). A negative difference may indicate that the pressure in the lungs is being allowed to 130 drop below the intended minimum level due to uncompensated leakage from the ventilator breathing circuit 131 or at the connections of an airway device.

132 Figures F.23 illustrates a typical expiratory phase of a primary-inflation in a Group 2 ventilation-mode, which 133 may be alternatively referred to as a BAP phase. This alternative name is not only more concise and less 134 ambiguous but leads naturally into the terminology of bi-level ventilation (the two levels of which are 135 indicated by orange broken lines).

136 Figures F.24 – F 27 illustrate the function of an expiratory-control algorithm.

137 F.24 shows its function during the BAP phase of the primary inflation of a Group 2 ventilation-mode when 138 each patient inspiration is supported by a pressure support inflation, whereas F. 25 shows the same BAP 139 phase but with either no support of with the support reduced to its ‘off’ or ‘zero’ level.

140 F.26 shows its function when spontaneous breathing is enabled during a primary inflation phase, which may 141 be alternatively referred to as a BAP-high phase.

142 F.27 shows the function of the expiratory-control algorithm in a CSV mode with and without pressure support.

143 In each of these illustrations the expiratory-pressure waveforms are determined by the expiratory-control 144 algorithm and maintained by the in-built functionality of either an ACAP adjunct that is active at the BAP level, 145 or an equivalent pressure-regulation function. The range of waveforms and how closely they are maintained 146 may be impaired with the use of some equivalent pressure-regulation functions.

147

148

3 Typical, measured 1 Airway expiratory-pressure pressure, waveform pAW 4 Dynamic lag of alveolar pressure

5 Typical, estimated alveolar pressure waveform

6 BAP 7 PEEP 8 total 2 (setting) (measured) PEEP Ambient pressure

150 a) Typical ideal expiratory-airway-pressure waveforms 151

3 Typical, measured expiratory-pressure 1 Airway waveform pressure, 4 Dynamic lag of pAW alveolar pressure 5 Typical, estimated alveolar-pressure waveform in impaired lung

10 dynamic PEEP 8 total 6 BAP 7 PEEP PEEP 2 (setting) (measured) Ambient pressure

155 Figure F.1 (1 of 2) — Illustrations of the application of BAP and PEEP terminology

156

157

158

159

160

3 Typical, algorithm- generated, expiratory- 1 Airway pressure waveform pressure, pAW 4 Typical, estimated alveolar pressure 5 Dynamic lag of waveform alveolar pressure

10 dynamic PEEP

8 6 BAP 7 PEEP total 2 (setting) (measured) PEEP Ambient pressure

162 a) Typical expiratory-airway-pressure waveforms with an impaired lung but with an expiratory-control 163 algorithm programmed to enhance initial evacuation of the gas in the upper airways by increasing 164 the initial pressure differential. 165

3 Typical, measured 1 Airway expiratory-pressure pressure, waveform pAW 4 Typical, estimated alveolar pressure waveform

10 dynamic 5 Dynamic lag of PEEP alveolar pressure

8 6 BAP 11 ΔPEEP 7 PEEP total (measured) PEEP 2 (setting) Ambient pressure

9 Expiratory phase ©NSJ 166 167 c) Typical expiratory-airway-pressure waveforms on a basic ventilator with inadequate set expiratory 168 time or excessive expiratory-limb resistance (e.g., due to kinked tube or increased resistance filter).

169 Figure F.1 (2 of 2) — Illustrations of the application of BAP and PEEP terminology

170

3 Typical displayed expiratory-pressure waveform

1 Airway 4 pressure, Inspiratory pAW pressure, pI or BAP-high

2 5 PEEP 6 BAP Ambient pressure

7 BAP time, tL or expiratory time

8 Inflation 9 Expiratory phase phase 10 Support-inflation cycle

11 BAP phase or primary expiratory phase

12 15 Spontaneous Inspiratory inspiration with flow pressure-support

172 Figure F.2 — The BAP/Expiratory phase

173

174

1 Airway pressure, pAW 1 2 2 1

3 BAP PEEP 4 PEEP PEEP

2 Ambient pressure

5 BAP (or Expiratory) time 175

176 a) Function of the expiratory-control algorithm during a BAP (or primary expiration) phase 177 with supported breaths

178

1 Airway 1 pressure, p AW 3

2 3 BAP PEEP 4 PEEP PEEP Ambient pressure

5 BAP (or Expiratory) time 179

180 b) Function of the expiratory-control algorithm during a BAP (or primary expiration) phase with 181 unassisted breaths

Notes to Figures F.6a) and F.6b): The expiratory-control algorithm also generates Typical expiratory-pressure the constant pressure portion of the intended Pressure-support waveforms, following a primary- primary expiratory pressure waveform, which the 1 inflation to assist 3 inflation, as may be determined 2 ACAPL adjunct acts to maintain in order to enable spontaneous by the expiratory-control unrestricted breathing when pressure-support is inspirations algorithm absent or turned off, and to compensate for leakage.

182

183 Figure F.3 (1 of 2) —Illustrations of the function of the expiratory-control algorithm on ventilators 184 with an ACAPL adjunct (or an equivalent function) during BAP phases

185

186

187

1 1 Airway pressure, pAW 6 BAP-high (or Inspiratory pressure) 1

2 3 BAP Ambient pressure

5 BAP-high time (or inspiratory time) 188

189 c) Function of the expiratory-control algorithm during a primary inflation phase

190

1 Airway 2 3 pressure, 1 pAW 1

PEEP 4 PEEP 3 BAP

2 Ambient pressure 191

192 d) Function of the expiratory-control algorithm in CSV modes

Notes to Figures F.6c) and F.6d): The expiratory-control algorithm also generates the constant Typical expiratory-pressure waveforms, Pressure-support pressure portion of the intended primary expiratory pressure following a support-inflation, at either inflation to assist 1 2 3 waveform, which the ACAP adjunct acts to maintain in order BAP levels, as may be determined by the spontaneous L to enable unrestricted breathing when pressure-support is expiratory-control algorithm inspirations absent or turned off, and to compensate for leakage. 193

194 Figure F.3 (2 of 2) — Illustrations of the function of the expiratory-control algorithm on ventilators 195 with an ACAPL adjunct (or an equivalent function) during BAP phases

196

197 Annex G 198 Conventions followed in this International Standard 199 (Informative)

200 G.1 Avoidance of repetition

201 In order to avoid the repetition of ‘in this International Standard’ in the text of the sub-clauses of this

202 International Standard, the expressions ‘is used’ and ‘in this vocabulary’ are to be read as being in reference 203 to the vocabulary of this International Standard.

204 G.2 Post-coordinated terms

205 The notes to some definitions make reference to post-coordinated terms. These are terms formed by the 206 combination of two defined terms, or of a defined term with a natural language word, to form a new

207 compound term. Usually, the additional term or word qualifies the base term by reference to an alternative 208 site, pressure level or point of occurrence within a respiratory cycle. It may place a restriction on the 209 applicability of the base term. Some of the most commonly used post-coordinated terms are defined in their 210 own right but users of the vocabulary are free to create other post-coordinated terms providing the

211 combination does not conflict with the meaning of the defined term.

212 G.3 Use of hyphens

213 Where hyphens are used in compound terms in the vocabulary of this International Standard their use is

214 considered to be good practice in the interests of readability and the minimisation of possible ambiguity but 215 their use is not normative.

216 G.4 Flows and pressures

217 In natural language, the word ‘flow’ denotes a steady movement of a body of fluid in the same general 218 direction. In order to denote a quantified flow the addition of the word ‘rate’ is necessary.

219 Similarly, the word ‘pressure’ in reference to a gas denotes a continuous physical force exerted against 220 something that the gas is in contact with. In order to denote it as a quantity the addition of a term such as

221 ‘level’ is necessary

222 In practice, when used as artificial-ventilation terms these additions seldom add meaning because the context 223 makes it clear when they are being used to represent a value. Because of the need for brevity, particularly 224 when used on user interfaces and in instructions for use, in the vocabulary of this International Standard, the

225 term ‘flow’ is taken to encompass the concept of a rate of flow and the term ‘pressure’ is taken to encompass 226 the concept of the pressure level. Where this is seen to create an ambiguity, or in applications where the use

227 of correct English is considered to be the priority, the terms ‘rate’ or ‘level’ may be added, respectively, where

228 appropriate.

229 G.5 Measurements

230 References to measured values in this vocabulary are to be taken as referring to values obtained from 231 measurement devices of systems, with the understanding that the actual measurement signal(s) may have

232 been appropriately processed to remove artefacts such as result from transients and ‘noise’ while 233 maintaining a declared accuracy; also that the site(s) of measurement may be away from the site to which

234 the measurement is referenced.

235 As a measurement, without further qualification or context, a recorded or displayed discrete value of a 236 quantity is that of a measurement at any point in time relative to a respiratory cycle or a specified elapsed 237 time. As the actual value of a quantity generally varies with time, even if regulated to a set value, a displayed 238 or recorded measured value has no meaning unless related to a specific point(s) in a respiratory cycle(s), 239 either by a qualifying term or by the context of use. An example of context is a displayed waveform, which is 240 clearly a continuous display of the actual measured value with progress of time. An example of a qualified 241 term is peak inspiratory pressure where the displayed value is the maximum measured value recorded during 242 a specified interval.

243 Although the definition of many terms relating to quantities in the vocabulary of this International Standard 244 specify a site at which it applies, there is no requirement that measurements are made at that site. In practice, 245 the site of actual measurement(s) may be anywhere in the ventilator breathing system providing the indicated 246 value is referenced to the specified site. The displayed or recorded measured value may be a calculated value 247 based on the results of more than one measurement at different sites.

248 As stated in sub-clause 4.0, the terms relating to quantities in this vocabulary are conceptual and are

249 independent of any specific system of units of measurement. It is for particular standards to specify any 250 requirements regarding measurement accuracy, the applicability and appropriateness of the measurement

251 methods that might be adopted, and units of measurement.

252 G.6 Multiplicity of terms

253 Artificial-ventilation may be described in many levels of granularity, depending on the objective of the 254 description. This vocabulary is based on a comprehensive conceptual model of such ventilation, which can 255 lead to an apparently confusing multiplicity of terms relating to certain aspects of that function when listed

256 in an all-encompassing vocabulary. It is to be emphasised that there is no requirement for manufacturers to 257 adopt every one of these terms, nor be required to provide their own equivalent to every one, in the labelling 258 of any specific ventilator.

259 G.7 Use of the terms expiration and exhalation

260 The use of terms relating to gas entering and leaving the patient’s lungs is fundamental to a vocabulary of 261 artificial ventilation. In normal speech in English, terms such as inspire, inhale, exhale and expire in their 262 various inflected forms are used for that purpose but each has connotations that makes it less than ideal in

263 at least one of its forms. In particular, inhalation has become associated with drug abuse and many clinicians 264 consider it to be inappropriate to speak of the patient expiring, in the presence of the patient or those close

265 to them. However, one of the basic objectives of a terminology standard is, wherever possible, to have only 266 one term to represent each concept. After much discussion the terms inspiration and expiration were

267 selected for this vocabulary but with the recognition that the use of alternative terms may be more 268 appropriate in potentially sensitive situations.

269 G.8 The use of symbols to represent defined terms

270 It is not a primary objective of this International Standard to specify requirements for symbols to be used as 271 alternatives to a defined terms. Symbols are typically used where space is limited, such as on a user interface,

272 but for many terms, currently used symbols are very diverse. Some manufacturers attempt to follow the 273 guidance and examples for mathematical signs and symbols to be used in natural sciences and technology

274 given in ISO 80000 but this guidance is not comprehensive.

275 Symbols have only been included as alternative preferred terms in this International Standard where there 276 appears to be a general consensus relating to their use in representing the main terms used when setting a 277 ventilator. Their use in product labelling is recommended but, as stated in Clause 2, not a requirement. 278 Where reproduced, this may be in fonts and styles to suit the application, except for letters designating

279 quantities. These should always in an italic style in accordance with the relevant parts of ISO 80000 & 280 ISO/IEC Directives Part 2: 2011, which specify that:

281 Symbols for quantities are generally single letters from the Latin or Greek alphabet, sometimes 282 with subscripts or other modifying signs. The quantity symbols are always written in italic

283 (sloping) type, irrespective of the type used in the rest of the text. No recommendation is made 284 or implied about the font of italic type in which symbols for quantities are to be printed. When,

285 in a given context, different quantities have the same letter symbol or when, for one quantity, 286 different applications or different values are of interest, a distinction can be made by use of

287 subscripts. A subscript that represents a physical quantity or a mathematical variable, such as 288 a running number, is printed in italic (sloping) type. Other subscripts, such as those

289 representing words or fixed numbers, are printed in roman (upright) type.

290 G.9 Bi-level terminology

291 The terminology in this vocabulary has been developed taking account of the additional functionality of 292 ventilators incorporating an ACAP adjunct. This is an advanced regulation function that, unlike conventional 293 pneumatic regulators, maintains a set airway pressure, irrespective of the direction of the airway flow. It is 294 used not only to enhance the regulation of the airway pressure during pressure-control inflations but also to 295 maintain the required pressure between primary inflations. This makes it possible for the patient to breathe 296 at any time, both concurrently with a primary inflation and during primary expiratory phases, with a minimal 297 imposed addition to the patient’s work of breathing. The set pressure for this regulation function may be 298 continuously constant, as when used with a CPAP mode, or in the form of a varying pressure waveform with 299 constant portions as is typically generated by either the inflation-type algorithm during inflation phases or 300 the expiratory-control algorithm during BAP (or expiratory) phases. During BAP phases it maintains a 301 constant pressure when there is no pressure-support, available or selected, and in the presence of any leakage.

302 On ventilators with this increased functionality, manufacturers have either labelled their modes as bi-level 303 modes, with corresponding terminology for the settings and displays, or have retained the classical 304 terminology for their modes, settings and displays, accompanied by a statement indicating that the patient is 305 free to breathe at any time.

306 As both approaches appear to have advantages and disadvantages, and as there is not yet any clear consensus 307 as to which is better from a human factors perspective, this vocabulary includes terms suitable for both

308 approaches. These terms are in most cases presented as alternatives but it is expected that they will always 309 be used consistently and in context, according to the mode designation adopted by the manufacturer.

310 It is expected that in future editions of this International Standard more specific guidance will be given on

311 the application of such terms.

312 Annex H 313 Terminology — Alphabetized index of defined terms 314 (Normative)

315 NOTE The ISO Online Browsing Platform (OBP) provides access to terms and definitions. 1

Term Source Term Source A/CV ISO 19223, —4.8.7 ACAP ISO 19223, —4.9.2

ACAPH ISO 19223, —4.9.4

ACAPL ISO 19223, —4.9.3 accompanying documents ISO 19223, —4.13.28 IEC 60601-1:2005, —3.4, modified actual value ISO 19223, —4.13.22 additional breath ISO 19223, —4.1.8 additional minute volume ISO 19223, —4.7.12 additional primary-inflation ISO 19223, —4.2.13 additional primary-inflation rate ISO 19223, —4.4.2.14 additional-breath rate ISO 19223, —4.4.2.7 adjunct ISO 19223, —4.9.1 adjustable airway pressure limit ISO 19223, —4.12.1.9 adjustable pressure limit ISO 19223, —4.12.1.9 airway ISO 19223, —4.13.2 airway device ISO 19223, —4.13.3 airway leak ISO 19223, —4.6.13 airway pressure ISO 19223, —4.5.1 airway pressure limit ISO 19223, —4.12.1.1 airway pressure release ventilation ISO 19223, —4.8.12 airway resistance ISO 19223, —4.13.4 alarm condition IEC 60601-1-8, — ISO 19223, —4.12.2.1

1 Available at: https://w w w .iso.org/obp/ui/#home

Term Source alarm condition ISO 19223, —4.12.2.1 IEC 60601-1-8 2006+A1:2012 Clause 3.1, modified alarm limit ISO 19223, —4.12.3.1 IEC 60601-1-8 2006+A1:2012 Clause 3.3, modified alternative mode name ISO 19223, —4.8.17 alternative ventilation mode name ISO 19223, —4.8.17 anaesthesia breathing system ISO 19223, —4.13.18 APL ISO 19223, —4.12.1.9 apnoea ventilation ISO 19223, —4.8.14 APRV ISO 19223, —4.8.12 artificial ventilation ISO 19223, —4.13.7 assist/control ventilation ISO 19223, —4.8.7 assisted breath ISO 19223, —4.1.14 assisted breath rate ISO 19223, —4.4.2.3 assured constant airway pressure ISO 19223, —4.9.2 assured constant airway pressure, ISO 19223, —4.9.4 high assured constant airway pressure, ISO 19223, —4.9.3 low

assured delivery ISO 19223, —4.2.14 assured minute volume ISO 19223, —4.7.11 assured ventilation ISO 19223, —4.8.5 auto trigger ISO 19223, —4.10.10 automatic ventilation ISO 19223, —4.13.8 backup ventilation ISO 19223, —4.8.15 BAP ISO 19223, —4.11.1 BAP phase ISO 19223, —4.3.3 BAP phase ISO 19223, —4.9.7 BAP pressure-low ISO 19223, —4.9.7 BAP time ISO 19223, —4.3.4 BAP-high ISO 19223, —4.9.10 BAP-high phase ISO 19223, —4.9.11

Term Source baseline airway-pressure ISO 19223, —4.11.1 bias flow ISO 19223, —4.6.8 bi-level PAP ISO 19223, —4.9.6 bi-level ventilation ISO 19223, —4.9.5 breath ISO 19223, —4.1.1 breath stacking ISO 19223, —4.10.11 breath synchronization ISO 19223, —4.10.7 breathe ISO 19223, —4.1.2 breathing therapy mode ISO 19223, —4.8.19 CMV continuous mandatory ISO 19223, —4.8.6 ventilation concave declining-flow pattern ISO 19223, —4.6.11 concurrent breath ISO 19223, —4.1.9 concurrent supported-breath rate ISO 19223, —4.4.2.9 concurrent unassisted-breath rate ISO 19223, —4.4.2.10 continuing airway pressure alarm ISO 19223, —4.12.2.3 condition continuous flow ISO 19223, —4.6.9 continuous mandatory ventilation ISO 19223, —4.8.6 continuous positive airway pressure ISO 19223, —4.8.13 continuous spontaneous ventilation ISO 19223, —4.8.10 controlled breath ISO 19223, —4.1.16 controlled breath rate ISO 19223, —4.4.2.5 CPAP ISO 19223, —4.8.13 CSV ISO 19223, —4.8.10 cycle time ISO 19223, —4.3.19 declining-ramp (flow pattern) ISO 19223, —4.6.10 delivered minute volume ISO 19223, —4.7.7 delivered volume ISO 19223, —4.7.2 delta PEEP ISO 19223, —4.11.6 Δ delta ISO 19223, —4.5.6 Δ inspiratory pressure ISO 19223, —4.5.7 Δ p ISO 19223, —4.5.7 Δ PEEP ISO 19223, —4.11.6

Term Source Δ pressure ISO 19223, —4.5.7 demand flow ISO 19223, —4.6.12 dPEEP ISO 19223, —4.11.5 dual-control ISO 19223, —4.2.5 dynamic PEEP ISO 19223, —4.11.5 emergency air intake port ISO 19223, —4.14.3 end-expiratory flow ISO 19223, —4.6.7 end-inspiratory flow ISO 19223, —4.6.4 end-inspiratory pressure ISO 19223, —4.5.8 exhaust port ISO 19223, —4.14.4 expiration ISO 19223, —4.1.11 expiratory flow ISO 19223, —4.6.5 expiratory hold ISO 19223, —4.3.8 expiratory pause ISO 19223, —4.3.6 expiratory phase ISO 19223, —4.3.2 expiratory pressure ISO 19223, —4.5.9 expiratory pressure-relief ISO 19223, —4.5.10 expiratory time ISO 19223, —4.3.1 expiratory-control algorithm ISO 19223, —44.11.3 expiratory-flow time ISO 19223, —4.3.5 expiratory-hold time ISO 19223, —4.3.9 expiratory-pause time ISO 19223, —4.3.7 expiratory-termination flow ISO 19223, —4.6.6 expired minute volume ISO 19223, —4.7.9 expired tidal volume ISO 19223, —4.7.4 flow trigger ISO 19223, —4.10.3 flow-regulation ISO 19223, —4.2.9 flow-termination ISO 19223, —4.10.15 gas input port ISO 19223, —4.14.7 gas intake port ISO 19223, —4.14.2 gas output port ISO 19223, —4.14.5 gas return port ISO 19223, —4.14.6 hazard ISO 14971:2007, 2.2

Term Source high airway pressure limit ISO 19223, —4.12.1.5 high airway-pressure alarm limit ISO 19223, —4.12.3.2 high airway-pressure-relief limit ISO 19223, —4.12.1.6 high airway-pressure-termination ISO 19223, —4.12.1.7 limit high-airway-pressure alarm ISO 19223, —4.12.2.2 condition high-pressure-relief limit ISO 19223, —4.12.1.6 high-pressure-termination limit ISO 19223, —4.12.1.7 I:E ratio ISO 19223, —4.3.21 IMV ISO 19223, —4.8.8 intermittent mandatory ventilation ISO 19223, —4.8.8 inflation ISO 19223, —4.2.1 Inflation Initiation and Termination ISO 19223, —4.10 inflation phase ISO 19223, —4.3.17 inflation-type ISO 19223, —4.2.2 initiate ISO 19223, —4.1.10 Inspiratory minute volume (external ISO 19223, —4.7.8 monitor) inspiration ISO 19223, —4.1.10 inspiratory effort ISO 19223, —4.1.7 inspiratory flow ISO 19223, —4.6.1 inspiratory hold ISO 19223, —4.3.15 inspiratory pause ISO 19223, —4.3.13 inspiratory phase ISO 19223, —4.3.11 inspiratory pressure ISO 19223, —4.5.2 inspiratory time ISO 19223, —4.3.10 inspiratory time fraction ISO 19223, —4.3.22 inspiratory volume ISO 19223, —4.7.3 inspiratory-flow time ISO 19223, —4.3.12 inspiratory-hold time ISO 19223, —4.3.16 inspiratory-pause time ISO 19223, —4.3.14 inspiratory-pressure relief ISO 19223, —4.5.5 inspiratory-termination flow ISO 19223, —4.6.3

Term Source intended purpose ISO 19223, —4.13.25 ISO 14971:2000, — 2.5 intended use ISO 19223, —4.13.25 ISO 14971:2000, — 2.5 ISO spontaneous breath rate ISO 19223, —4.4.1.3 leakage minute volume ISO 19223, —4.7.10 leakage tidal volume ISO 19223, —4.7.5 limit ISO 19223, —4.13.23 low inspiratory-pressure alarm ISO 19223, —4.12.2.4 condition low inspiratory-pressure alarm limit ISO 19223, —4.12.3.3 low PEEP alarm condition ISO 19223, —4.12.2.5 lung ISO 19223, —4.13.14 lung compliance ISO 19223, —4.13.5 lung ventilator ISO 19223, —4.13.1 ISO 80601-2-12:2011, — 201.3.222 modified lungs ISO 19223, —4.13.15 mandatory ISO 19223, —4.10.9 mandatory ventilation ISO 19223, —4.8.5 maximum deliverable airway ISO 19223, —4.12.1.4 pressure maximum deliverable pressure ISO 19223, —4.12.1.4 maximum limited airway pressure ISO 19223, —4.12.1.3 ISO/IEC 80601-2-12: 2011, — 201.3.214 modified by the addition of semantic notes maximum limited pressure ISO 19223, —4.12.1.3 maximum settable inspiratory ISO 19223, —4.12.1.8 pressure measured ISO 19223, —4.13.20 mechanical ventilation ISO 19223, —4.13.9 minute volume ISO 19223, —4.7.6 MMV ISO 19223, —4.8.11 minimum minute volume ISO 19223, —4.8.11

Term Source natural breathing ISO 19223, —4.1.4 negative-pressure ventilation ISO 19223, —4.13.11 NIV ISO 19223, —4.13.12 non-concurrent unassisted-breath ISO 19223, —4.4.2.11 rate non-invasive ventilation ISO 19223, —4.13.12 normal condition ISO 19223, —4.13.26 IEC 60601-1:2005, —3.70] normal use ISO 19223, —4.13.24 IEC 60601-1:2005, —3.71 NPV ISO 19223, —4.13.11 patient-connection port ISO 19223, —4.14.8 patient-trigger event ISO 19223, —4.10.6 patient-triggered inflation rate ISO 19223, —4.4.2.12 patient-triggered primary inflation ISO 19223, —4.4.2.8 rate PC ISO 19223, —4.2.4 peak inspiratory flow ISO 19223, —4.6.2 peak inspiratory pressure ISO 19223, —4.5.3 PEEP ISO 19223, —4.11.1

pES ISO 19223, —4.2.7 phase time ratio ISO 19223, —4.3.21 plateau inspiratory pressure ISO 19223, —4.5.4 plateau pressure ISO 19223, —4.5.4

pLim ISO 19223, —4.12.1.2 port ISO 19223, —4.14.1 positive end-exhalation pressure ISO 19223, —4.11.2 positive pressure inflation ISO 19223, —4.2.1 positive-pressure ventilation ISO 19223, —4.13.10 preset value ISO 19223, —4.13.21 pressure limit ISO 19223, —4.12.1.1 pressure limited ISO 19223, —4.12.1.2 pressure trigger ISO 19223, —4.10.4 pressure-control ISO 19223, —4.2.4

Term Source pressure-high ISO 19223, —4.9.10 pressure-high phase ISO 19223, —4.9.11 pressure-low phase ISO 19223, —4.9.8 pressure-regulation ISO 19223, —4.2.10 pressure-support ISO 19223, —4.2.6 pressure-termination ISO 19223, —4.10.16 primary inflation rate ISO 19223, —4.4.2.1 primary-inflation ISO 19223, —4.2.12 primary-inflation cycle ISO 19223, —4.3.20 proportional effort support ISO 19223, —4.2.7 PS ISO 19223, —4.2.6 rate ISO 19223, —4.4.1.1 remote inflation-initiation ISO 19223, —4.10.13 respiratory activity ISO 19223, —4.1.6 respiratory cycle ISO 19223, —4.3.18 respiratory cycle time ISO 19223, —4.3.19 respiratory system ISO 19223, —4.13.16 respiratory system coefficients ISO 19223, —4.13.17 rise time ISO 19223, —4.2.11 RR ISO 19223, —4.4.1.2

RRspont ISO 19223, —4.4.1.3

RRv ent ISO 19223, —4.4.1.4 S/T ISO 19223, —4.2.8 set ISO 19223, —4.13.19 SIMV ISO 19223, —4.8.9 single fault condition ISO 19223, —4.13.27 IEC 60601-1:2005, —3.116 spontaneous breath ISO 19223, —4.1.3 spontaneous rate ISO 19223, —4.4.1.3 spontaneous respiratory rate ISO 19223, —4.4.1.3 spontaneous/timed pressure-control ISO 19223, —4.2.8 superordinate mode ISO 19223, —4.8.18 supported breath ISO 19223, —4.1.13

Term Source support-inflation ISO 19223, —4.2.15 support-inflation rate ISO 19223, —4.4.2.2 Supralaryngeal airway ISO 11712, —3.10 synchronisation window ISO 19223, —4.10.8 synchronised breath ISO 19223, —4.1.15 synchronised breath rate ISO 19223, —4.4.2.4 synchronised intermittent mandatory ISO 19223, —4.8.9 ventilation systematic ventilation-mode name ISO 19223, —4.8.16

tB ISO 19223, —4.3.4 TC ISO 19223, —4.13.13 termination ISO 19223, —4.10.14

ti ISO 19223, —4.3.10

tI:tTOT ISO 19223, —4.3.22 tidal volume ISO 19223, —4.7.1 time-high ISO 19223, —4.9.12 time-low ISO 19223, —4.14.5 time-low ISO 19223, —4.9.9 time-termination ISO 19223, —4.10.17

tL ISO 19223, —4.14.5 total inflation rate ISO 19223, —4.4.2.13 total PEEP ISO 19223, —4.11.4 total rate ISO 19223, —4.4.1.2 total respiratory rate ISO 19223, —4.4.1.2 tPEEP ISO 19223, —4.11.4 trigger ISO 19223, —4.10.2 trigger event ISO 19223, —4.10.6 trigger level ISO 19223, —4.10.5 tube compensation ISO 19223, —4.13.13 unassisted breath ISO 19223, —4.1.12 unassisted breath rate ISO 19223, —4.4.2.6 unrestricted breathing ISO 19223, —4.1.5

Term Source VBS ISO 19223, —4.13.18 ISO 4135:2001, —3.1.6 and 4.1.1, modified IEC 80601-2-12:2011, — 201.3.221, modified VBS leak ISO 19223, —4.6.14 VC ISO 19223, —4.2.3

VDEL ISO 19223, —4.7.2 ventilation ISO 19223, —4.13.6 ventilation mode ISO 19223, —4.8.2 ventilation-mode Group 1 ISO 19223, —4.8.4.1 ventilation-mode Group 1a ISO 19223, —4.8.4.1.1 ventilation-mode Group 1b ISO 19223, —4.8.4.1.2 ventilation-mode Group 2 ISO 19223, —4.8.4.2 ventilation-mode Group 2a ISO 19223, —4.8.4.2.1 ventilation-mode Group 2b ISO 19223, —4.8.4.2.2 ventilation-mode Group 3 ISO 19223, —4.8.4.3 ventilation-mode Group 3a ISO 19223, —4.8.4.3 ventilation-mode Group 3b ISO 19223, —4.8.4.3.2 ventilation-mode groups ISO 19223, —4.8.4 ventilation-pattern ISO 19223, —4.8.3 ventilator ISO 19223, —4.13.1 ventilator breathing system ISO 19223, —4.13.18 ISO 4135:2001, —3.1.6 and 4.1.1, modified IEC 80601-2-12:2011, — 201.3.221, modified ventilator breathing system leak ISO 19223, —4.6.14 ventilator inspiration ISO 19223, —4.2.1 ventilator mode ISO 19223, —4.8.1 ventilator-initiated inflation rate ISO 19223, —4.4.1.4 ventilator-initiated rate ISO 19223, —4.4.1.4 ventilator-initiation ISO 19223, —4.10.12

VI ISO 19223, —4.7.3

VM ISO 19223, —4.7.6

Term Source

Vmaddn ISO 19223, —4.7.12

Vmassd ISO 19223, —4.7.11

VMDEL ISO 19223, —4.7.7

VME ISO 19223, —4.7.9

VMI ISO 19223, —4.7.8

VMLeak ISO 19223, —4.7.10 volume targeted ISO 19223, —4.2.16 volume-control ISO 19223, —4.2.3 vt ISO 19223, —4.2.16 VT ISO 19223, —4.7.1

VTE ISO 19223, —4.7.4

VTLeak ISO 19223, —4.7.5

316

317 Annex I 318 Index of figures 319 (Informative)

320 Annex C Figures

321 Figure C.1 - Format used in this International Standard for representations of ventilation patterns and 322 inflation-types

323 Figure C.2 (1 of 5) - Illustrations of the application of defined ventilation terms in designating key features of 324 typical inflation waveforms

325 a) Typical airway pressure and flow waveforms for a pressure-control inflation 326 b) Typical airway pressure and flow waveforms for a pressure-support inflation 327 c) Typical airway pressure and flow waveforms for a flow-terminated pressure-control inflation 328 d) Typical airway pressure and flow waveforms for volume-control inflation with an inspiratory pause 329 e) Typical airway pressure and flow waveforms for a pressure-limited volume-control inflation

330 Figure C.3 - Typical airway pressure and flow waveforms for a CMV-PC mode

331 Figure C.4 - Typical airway pressure and flow waveforms for a CMV-PC mode

332 Figure C.5 - Typical airway pressure and flow waveforms for a CMV- PC mode set with extended phase 333 times

334 Figure C.6 - Typical airway pressure and flow waveforms for a CMV- PC mode set with an extreme 335 inverse I:E ratio

336 Figure C.7 - Typical airway pressure and flow waveforms for an A/CV - PC mode

337 Figure C.8 - Typical airway pressure and flow waveforms for an A/CV – VC mode

338 Figure C.9 - Typical airway pressure and flow waveforms for an A/CV – PC mode 339 (No pressure-support inflation-type is permitted with this mode but it could be optionally labelled: Bi-level 340 ventilation (A/CV – PC ).)

341 342 Figure C.10 - Typical airway pressure and flow waveforms for an SIMV- PC\PS mode

343 344 Figure C.11 - Typical airway pressure and flow waveforms for variations on an SIMV- PC\PS\PS mode 345 a) with typical settings for the simulation of Bi-level ventilation 346 b) with typical settings for the simulation of APRV 347 c) with a PC[S] primary inflation-type and optionally labelled as a ‘Bi-level ventilation’ mode 348 d) with a PC[S] primary inflation-type, no pressure-support at BAP level and optionally labelled as 349 intended for APRV (airway pressure release ventilation)

350 351 Figure C.12 - Typical airway pressure and flow waveforms for a CSV - PS mode

352 Figure C.13 – Characteristics of a concurrent breath

353 Figure C.14 – Ventilation patterns

354 a) Key to symbols used in b) to f) 355 b) CMV ventilation-pattern 356 c) Assist/Control ventilation-pattern 357 d) IMV ventilation-pattern 358 e) SIMV ventilation-pattern 359 f) CSV ventilation-pattern

360 I.1 Annex E Figures

361 Figure E.1 — Diagram showing the concepts of the relationship between breath and inflation related terms

362 in the vocabulary of the International Standard

363 I.2 Annex F Figures

364 Figure F.1 Illustrations of the application of BAP and PEEP terminology

365 a) Typical ideal expiratory-airway-pressure waveforms 366 b) Typical expiratory-airway-pressure waveforms with an impaired lung 367 c) Typical expiratory-airway-pressure waveforms with an impaired lung but with an expiratory-control 368 algorithm programmed to enhance initial evacuation of the gas in the upper airways by increasing

369 the initial pressure differential. 370 d) Typical expiratory-airway-pressure waveforms on a basic ventilator with inadequate set expiratory 371 time or excessive expiratory-limb resistance (e.g., due to kinked tube or increased resistance filter).

372 Figure F.2 - The BAP/Expiratory phase

373 Figure F.3 Illustrations of the function of the expiratory-control algorithm on ventilators with an ACAPL 374 adjunct (or an equivalent function) during BAP phases

375 c) Function of the expiratory-control algorithm during a BAP (or primary expiration) phase with 376 supported breaths 377 d) Function of the expiratory-control algorithm during a BAP (or primary expiration) phase with 378 unassisted breaths 379 e) Function of the expiratory-control algorithm during a primary inflation phase 380 f) Function of the expiratory-control algorithm in CSV modes

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