Ventilator Initiation

NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning, LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC 9781284139860_CH06_311_366.indd 311

© Thep Urai/Shutterstock OBJECTIVES Summary Management ofSpecificDiseaseStatesandConditions Patient Assessment Initial Ventilator Settings Choice ofMode Choice ofaVentilator Establishment oftheAirway Methods ofVentilation Goals ofMechanicalVentilation Introduction OUTLINE Neuromuscular Disease Acute RespiratoryDistress Syndrome Severe Pneumonia Acute ExacerbationofCOPD Asthma Humidification Alarms andLimits PEEP andCPAP Inspiratory Phase,ExpiratoryandI:ERatio Breath Trigger Tidal Volume andRate Mode Other ModesofVentilation Major ModesofVentilation VentilatoryFull andPartial Support More onNomenclature Tracheostomy Endotracheal Intubation Positive-Pressure Ventilation Negative-Pressure Ventilation 5. 3. 2. 1. 4. NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC

pressure ventilation. Explain theadvantagesanddisadvantages ofnegative- ventilation. Overview thehistoricaldevelopment ofnegative-pressure Describe themajorgoalsofmechanical ventilation. Identify thefourmajorindicationsformechanicalventilation. Describe theprimaryfunctionofamechanicalventilator. © Jones & Bartlett Learning LLC, an Ascend Learning Company. NOTFORSALEORDISTRIBUTION. LLC, anAscendLearning © Jones&Bartlett Learning NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC Ventilator Initiation David C.ShelledyandJay I.Peters CHAPTER 6 NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning, LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC 21. 19. 20. 18. 17. 16. 15. 14. 13. 12. 11. 10. 9. 8. 7. 6.

variable: flowtrigger, pr Explain eachofthefollowingtermsrelated tothetrigger ventilation topatient-trigger Define thetermtriggervariableandcompare time-triggered ventilation (HFV). ventilatory assist(NAVA), andhigh-frequency assist ventilation(PAV), automode,neutrallyadjusted airway pressure-release ventilation(APRV),proportional ventilation(ASV),ventilation (MMV),adaptivesupport adaptive pressure contr Explain theuseofothermodesventilationtoinclude explain theadvantagesanddisadvantagesofeach. Define eachofthefivemajormodesventilationand each. suppor Explain methodsforproviding ventilatory fullandpartial and targeting scheme. of ventilationemployed:control variable,breath sequence, Explain eachofthefollowingtermsusedtodefinemode choosing amechanicalventilator. Summarize thefactorsthatshouldbeconsidered when used toprovide invasivemechanicalventilation. Contrast endotrachealintubationandtracheostomywhen invasive mechanicalventilation. Describe methodsandstepstoestablishtheairwayfor Describe initialventilatorsettingsforNIV. disadvantages ofnoninvasiveventilation(NIV). Explain theindications,contraindications,advantages,and and continuousspontaneousventilation(CSV). ventilation (CMV),intermittentmandatory(IMV), Define eachofthefollowing:continuousmandatory control ventilation(PCV). Compare pressure-suppor ventilation (PC). Compare volume-control (VC)andpressur cycled, andflowcycled. the inspiratoryphase:volumecycled,pressure cycled,time Explain howeachofthefollowingcyclevariablesterminates each term. ventilation intermsofthetriggervariableassociatedwith breath Define eachofthefollowingcommonlyusedterms:assist , NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC t andcontrastadvantagesdisadvantagesof control breath, assist-control, andcontrolled essure trigger, andautotrigger. ol (APC),mandatoryminute t ventilation(PSV)andpressure- ed ventilation. NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC NOT FORSALEORDISTRIBUTION © Jones&BartlettLearning,LLC e-control

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22. Describe initial ventilator setup for adult patients to include expiratory time and I:E ratio, oxygen concentration, © Jones & Bartlettmode, tidalLearning, volume, rate, LLC inspiratory pressure, breath © Jones PEEP/& Bartlett CPAP, alarms Learning, and limits, and LLC humidification. NOT FOR SALEtrigger, OR pressure DISTRIBUTION rise time or slope, inspiratory time, NOT FOR SALE OR DISTRIBUTION

KEY TERMS adaptive pressure high-frequency positive end-expiratory secondary breaths control (APC) © Jones &positive-pressure Bartlett Learning, LLCpressure (PEEP) ©servo Jones targeting & Bartlett (r) Learning, LLC adaptive support ventilation (HFPPV) positive-pressure ventilation set-point targeting (s) ventilation (ASV) NOT FORhigh-frequency SALE OR DISTRIBUTIONpressure control-continuous NOTspontaneous FOR SALEbreaths OR DISTRIBUTION adaptive targeting (a) ventilation (HFV) mandatory ventilation synchronized intermittent airway pressure-release imposed work of (PC-CMV) mandatory

ventilation (APRV) breathing (WOBI) pressure control-continuous ventilation (SIMV) assist-control volume intelligent targeting (i) spontaneous targeting scheme ventilation intermittent mandatory ventilation (PC-CSV) time cycled autotriggering© Jones & Bartlett Learning,ventilation LLC(IMV) pressure control© Jones & Bartletttime-triggered Learning, breaths LLC automodeNOT FOR SALE OR invasiveDISTRIBUTION ventilation intermittentNOT mandatory FOR SALEvolume OR control-continuous DISTRIBUTION biovariable targeting (b) lung-protective ventilation (PC-IMV) mandatory ventilation continuous positive airway ventilatory strategy pressure-control (VC-CMV) pressure (CPAP) mandatory breaths ventilation (PCV) volume control controlled ventilation mandatory minute pressure cycled intermittent mandatory dual targeting (d) ventilation (MMV) pressure-regulated volume ventilation (VC-IMV) © Jones & flowBartlett cycled Learning, LLCnegative-pressure © Jonescontrol & Bartlett(PRVC) Learning,volume LLC control (VC) NOT FOR SALEfull ventilatory OR DISTRIBUTION support ventilation NOTpressure-support FOR SALE OR DISTRIBUTIONvolume cycled high-frequency jet neurally adjusted ventilation (PSV) volume support (VS) ventilation (HFJV) ventilatory assist (NAVA) primary breaths work of breathing (WOB) high-frequency oscillatory noninvasive ventilation (NIV) proportional assist ventilation (HFOV) optimal targeting (o) ventilation (PAV) high-frequency percussive partial ventilatory support rapid sequence ventilation (HFPV) © Jonespatient-triggered & Bartlett Learning,breaths LLCintubation (RSI) © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Introduction The decision to initiate mechanical ventilatory support The primary function of a mechanical ventilator is to aug- must also consider contraindications to mechanical venti- ment© Jonesor replace & Bartlettnormal ventilation. Learning, Thus, LLC mechanical lation, and possible© Jones complications & Bartlett and hazards.Learning, Hazards LLC of ventilationNOT FOR may be SALE required OR when DISTRIBUTION spontaneous breathing mechanical NOTventilation FOR include SALE ventilator-associated OR DISTRIBUTION lung is insufficient or absent. The decision to initiate mechani- injury (VALI), ventilator-associated pneumonia (VAP), cal ventilatory support should be based on a thorough and increased work of breathing (WOB) and ventilatory patient assessment, sound clinical judgment, and an un- muscle dysfunction due to inappropriate ventilator set- Positive-pressure ventilation derstanding of the indications, contraindications, compli- tings. may result in reduced © Jones & cations,Bartlett and Learning, hazards of mechanical LLC ventilation. The most© Jonesvenous & return Bartlett to the rightLearning, heart, decreased LLC cardiac output, and hypotension. Other possible adverse effects of NOT FOR SALEcommon OR reason DISTRIBUTION for initiation of mechanical ventilatoryNOT FOR SALE OR DISTRIBUTION support is acute respiratory failure. Other common diag- mechanical ventilation include the development of baro- noses associated with the need for mechanical ventilatory trauma (e.g., pneumothorax, pneumomediastinum), air- support include acute exacerbation of chronic obstruc- way problems (e.g., accidental bronchial intubation, airway tive pulmonary disease (COPD), coma, multiple trauma, occlusion), and ventilator system failure. Chapter 2 reviews and neuromuscular disease.© Jones The &respiratory Bartlett care Learning, clinician LLCrespiratory failure, while Chapter© Jones5 provides & a Bartlettdiscussion Learning, LLC of the indications for mechanical ventilation. should be aware of predisposingNOT FOR factors SALE for OR the developDISTRIBUTION- NOT FOR SALE OR DISTRIBUTION ment of acute respiratory failure, the clinical manifesta- Once the decision has been made to institute me- tions of acute respiratory failure, and the indications chanical ventilatory support, a number of choices for mechanical ventilation. These indications include: must be made. Most patients will receive some form of positive-pressure ventilation, although ■■ Apnea negative-pressure ventilation may be appropriate in ©■■ Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Acute ventilatory failure a few select cases. Certain patients may do well with NOT■■ FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Impending ventilatory failure noninvasive positive-pressure ventilation (NPPV), while ■■ Severe oxygenation problems (refractory others may require endotracheal (ET) intubation and in- hypoxemia) vasive mechanical ventilation. Many modern ventilators Other possible indications include the administra- allow the clinician to choose between providing partial © Jones & tionBartlett of general Learning, anesthesia, LLC protection of the airway in © Jonesand full & ventilatory Bartlett support,Learning, and a LLC large number of dif- NOT FOR SALEthe absence OR of DISTRIBUTION a gag reflex, and the need for deep seda-NOTferent FOR ventilator SALE ORmodes DISTRIBUTION are currently available. Follow- tion and/or neuromuscular blockade. ing selection of the appropriate mechanical ventilator

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© Jones &and Bartlett initial mode Learning, of ventilation, LLC the respiratory care cli-© Jonesoutput. & Other Bartlett hazards Learning, include barotrauma, LLC ventilator- nician must choose the initial ventilator settings. Each NOTassociated FOR SALE pneumonia OR DISTRIBUTION (VAP), oxygen toxicity, and ven- NOT FOR SALEof these ORchoices DISTRIBUTION will be discussed in this chapter. tilator system failure. VALI may be caused by elevated transpulmonary RC Insight pressures during positive-pressure breathing. Dur- ing mechanical ventilation, plateau pressure (Pplateau) © Jones & Bartlett Learning, LLCreflects alveolar pressure and,© inJones turn, transpulmonary & Bartlett Learning, LLC Major indications for ventilator initiation include lung-protective ventilatory strategy NOT FOR SALE OR DISTRIBUTIONpressure. A NOT FOR SALE should OR DISTRIBUTION apnea, acute ventilatory failure, impending venti- be employed, which includes limiting plateau pressure latory failure, and severe oxygenation problems. 1,2 to less than 30 cm H2O for most patients. It should be noted, however, that patients with decreased thoracic Goals of Mechanical Ventilation compliance may have decreased transpulmonary pres- © Jones & Bartlett Learning, LLC sures; in such© cases,Jones higher & Bartlett Pplateau may Learning, be applied (if LLC MechanicalNOT FOR ventilation SALE can OR normalize DISTRIBUTION alveolar ventila- needed) withoutNOT causing FOR overdistention.SALE OR DISTRIBUTION Smaller tidal tion and Paco2, reverse hypoxemia, relieve respiratory volumes (e.g., 6 to 8 mL/kg) and appropriate levels of distress, and allow for recovery from ventilatory muscle PEEP are used in patients with acute respiratory distress fatigue. Properly applied, mechanical ventilation may syndrome (ARDS) to avoid ventilator-induced lung in- decrease ventilatory muscle and myocardial oxygen jury (VILI). An extensive review suggested that with < © Jones & consumptionBartlett Learning, and improve LLC oxygen delivery to the tis- © JonesARDS, & if BartlettPplateau remained Learning, 30 cm LLC H2O, a slightly larger NOT FOR SALEsues. Mechanical OR DISTRIBUTION ventilation may also allow for deep NOTtidal FOR volume SALE (Vt) OR (8 toDISTRIBUTION 10 mL/kg ideal body weight sedation and neuromuscular blockade for certain pro- [IBW]) did not affect outcomes.3 Properly applied, cedures to be performed or in cases of severe distress PEEP can stabilize unstable lung units and avoid repeti- and agitation, delirium, or severe, refractory hypoxemia. tive inflation and deflation of alveoli, thus reducing the However, for most patients, sedation should only be likelihood of additional injury. As a point of interest, the applied as necessary ©for Jones patient comfort& Bartlett and effective Learning, LLCterm ventilator-induced lung© injury Jones (VILI) & isBartlett used when Learning, LLC ventilation. In the presenceNOT FORof a closed SALE head OR injury DISTRIBUTION (e.g., the ventilator can be clearly identifiedNOT FOR as the SALE source OR of DISTRIBUTION severe traumatic brain injury) or cerebral edema, mech- the injury. Because it can be difficult to be sure that the anical ventilation may be used for a short period of time ventilator caused any lung injury observed (e.g., VILI), to reduce the Paco2, cause cerebral vasoconstriction, the term ventilator-associated lung injury (VALI) is and reduce intracranial pressure (ICP). Initial hyper- commonly used. ventilation© Jones should & Bartlett be avoided Learning, in such patients LLC except as © Jones & Bartlett Learning, LLC a life-savingNOT FOR measure SALE when OR cerebral DISTRIBUTION herniation has oc- MethodsNOT of FORVentilation SALE OR DISTRIBUTION curred or is imminent. Methods of providing mechanical ventilatory sup- The primary goals of mechanical ventilation are to port include negative-pressure ventilation, positive- provide adequate alveolar ventilation, ensure adequate pressure ventilation, partial ventilatory support, tissue oxygenation, restore and maintain acid-base full ventilatory support, volume-control ventila- homeostasis, and reduce the WOB. Mechanical ventila- © Jones & Bartlett Learning, LLC © Jonestion, pressure-control & Bartlett Learning, ventilation, LLC and various ven- tory support should be adjusted to ensure patient com- tilatory modes that employ automated targeting NOT FOR SALEfort and OR safety DISTRIBUTION and minimize harmful side effects and NOT FOR SALE OR DISTRIBUTION schemes (e.g., proportional assist ventilation [PAV], complications. Mechanical ventilatory support should pressure-regulated volume control [PRVC], or also be applied in such a fashion as to promote prompt adaptive support ventilation [ASV]). liberation of the patient from the ventilator. It should also be noted that mechanical© Jones ventilation & Bartlett may Learning,reduce LLCNegative-Pressure Ventilation© Jones & Bartlett Learning, LLC cardiac work by supporting oxygenation and relieving stress on the heart. MechanicalNOT FOR ventilation SALE ORmay alsoDISTRIBUTION The tank ventilator or “iron lung”NOT wasFOR developed SALE by OR DISTRIBUTION incorporate positive end-expiratory pressure (PEEP) Drinker, McKhann, and Shaw at Harvard University or continuous positive airway pressure (CPAP) to help in 1928; an improved commercial version was intro- restore or maintain lung volumes, improve compliance, duced by John H. Emerson in 1932. The Emerson iron and© prevent Jones or &treat Bartlett atelectasis. Learning, In cases of LLC severe tho- lung was in© widespread Jones & use Bartlett during the Learning, polio epidemics LLC racicNOT trauma FOR with SALE a flail ORchest DISTRIBUTIONrequiring ventilatory sup- in the UnitedNOT States FOR in the SALE 1940s andOR 1950s DISTRIBUTION and con- port, mechanical ventilation may be helpful for internal tinued to be manufactured until 1970. Other forms of stabilization of the thorax. negative-pressure ventilation include the Port-a-Lung, Initiation of mechanical ventilation is not without chest cuirass, and bodysuit. These devices have been risk. Hazards include ventilator-associated lung in- used to provide intermittent or continuous negative- © Jones & juryBartlett (VALI), Learning, increased WOB LLC (which may be caused © Jonespressure & ventilatoryBartlett Learning,support to patients LLC with chronic NOT FOR SALEby patient–ventilator OR DISTRIBUTION asynchrony), ventilatory muscle NOTconditions FOR SALE (e.g., polio,OR DISTRIBUTION other neuromuscular disease, or dysfunction, and decreased venous return and cardiac chronic restrictive disorders). Negative-pressure devices

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© Jones &do Bartlett not require Learning, the placement LLC of an artificial airway © Jonesof inspiration, & Bartlett and airway Learning, pressure LLC will fall to a plateau and are relatively easy to use to support patients with during this inspiratory pause. This plateau pressure NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION chronic ventilatory failure. Negative-pressure ventila- (Pplateau) represents the point at which Paw and Pa have tors enclose the thorax within a chamber, shell, or body equilibrated (assuming no spontaneous breathing ef- suit and apply a negative pressure to effect inspiration. forts are made during the inspiratory pause). Monitor- This negative pressure is then released to allow for ex- ing PIP and Pplateau during mechanical ventilation in the piration. Initial settings© Jones for adults & were Bartlett at a rate Learning, of 12 to LLCvolume-control mode provides© valuableJones information& Bartlett Learning, LLC 24 breaths/min withNOT a negative FOR inspiratory SALE ORpressure DISTRIBUTION of used to detect important clinicalNOT changes FOR asSALE well as OR al- DISTRIBUTION –10 to –35 cm H2O. The level of negative pressure ap- lowing for the calculation of the patient’s static total plied determines the degree of inspiratory support and compliance (Cst) and airway resistance (Raw). resultant tidal volume. Following the inspiratory phase, the ventilator allows Advantages of negative-pressure ventilators included airway pressure to fall to a baseline value, and expira- the© maintenance Jones & ofBartlett the natural Learning, airway, which LLC allowed tion occurs ©due Jones to the natural & Bartlett elastic recoilLearning, of the lungs. LLC patientsNOT to FOR talk or SALE eat, and OR the relativeDISTRIBUTION simplicity of the Baseline pressureNOT mayFOR be SALEambient OR barometric DISTRIBUTION pressure ventilator controls. Problems associated with negative- (conventionally referred to as zero) or elevated with the pressure ventilation include difficulties in accessing the application of PEEP or CPAP. When properly applied, patient for procedures, bathing, or turning. Most de- positive-pressure breathing can be accomplished with vices were large and bulky and difficult to move. Main- little or no work on the part of the patient. taining ventilation could be difficult because of leaks. © Jones & Bartlett Learning, LLC © JonesTerminology & Bartlett Learning, LLC NOT FOR SALEIn the case OR of DISTRIBUTION full-body tanks, abdominal venous bloodNOT FOR SALE OR DISTRIBUTION pooling could occur, resulting in reduced venous return Terminology used to describe positive-pressure ventila- and acute hypotension or “tank shock.” In the absence of tion can be confusing, due to the wide variety of terms an artificial airway, negative-pressure ventilation could in common in use. To further complicate the taxonomy result in upper airway soft tissue obstruction, and nega- for mechanical ventilation, different ventilator manufac- 4,5 tive pressure ventilation© Jones is contraindicated & Bartlett in patientsLearning, LLCturers use different terms to ©refer Jones to the &same Bartlett modes. Learning, LLC with obstructive sleepNOT apnea. FOR Because SALE of these OR prob- DISTRIBUTIONThe trigger variable refers NOTto the methodFOR SALE that begins OR DISTRIBUTION lems, negative-pressure ventilators are inappropriate inspiration (i.e., the changeover from expiration to in- in most modern acute care and ICU settings. Although spiration). The two most common trigger variables are negative-pressure ventilation may be useful in a hand- time and patient effort (i.e., patient triggered), which ful of long-term care patients based on patient prefer- may be further described as a (negative) pressure trigger ence,© itsJones use has & been Bartlett largely Learning,replaced by noninvasive LLC or flow trigger.© JonesPatient-triggered & Bartlett breaths Learning, are initiated LLC positive-pressureNOT FOR SALE ventilation OR (NPPV). DISTRIBUTION As late as 2014, by the patientNOT independent FOR SALE of the ORventilator DISTRIBUTION rate set- a few negative-pressure ventilators remained in use in tings. Patient-triggered breaths are commonly referred the United States. Other devices that have been used to as assisted breaths, although using this terminology in the past to noninvasively support ventilation include for patient-triggered breaths has been discouraged by the rocking bed and pneumobelt. Diaphragmatic pacing some authors.4,5 Autotriggering refers to unintentional © Jones & (akaBartlett phrenic Learning, nerve pacing) LLC provides another example of© Jonesinitiation & Bartlett of breath deliveryLearning, by the LLC ventilator, most often ventilatory support that does not require insertion of an due to inappropriate trigger sensitivity settings and/or NOT FOR SALEendotracheal OR DISTRIBUTIONor tracheostomy tube for patients with ap-NOTmovement FOR SALE of the OR ventilator DISTRIBUTION circuit. nea or severe hypoventilation due to bilateral diaphrag- As noted, in common clinical parlance, the term matic paralysis. assisted breath is often used to refer to breaths that Positive-Pressure Ventilation are patient triggered. In a similar fashion, control © Jones & Bartlett Learning, LLCbreaths commonly refer to breaths© Jones that are & timeBartlett trig- Learning, LLC During positive-pressure ventilation, the ventilator ap- gered, and the term assist-control is commonly used plies a positive pressureNOT via FORmask, endotrachealSALE OR tube,DISTRIBUTION to refer to a mode of ventilationNOT that FOR may beSALE patient OR or DISTRIBUTION tracheostomy tube, or other interface during inspira- time triggered, depending on which occurs first. Con- tion. This positive proximal airway pressure (Paw) trolled ventilation, in this context, is used to refer to a creates a pressure gradient between the mouth or air- mode of ventilation in which every breath is time trig- way© and Jones the alveoli & Bartlett (Pa), and Learning, inspiration occurs. LLC The gered. These© latterJones terms & Bartlettshould probably Learning, be avoided LLC peak inspiratory pressure (PIP) is the highest pressure in favor of simply describing the trigger method that NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION5 reached during the inspiratory phase. In general, PIP starts a breath (e.g., patient or time triggered). It occurs at the end of inspiration during volume-control should be noted that other trigger variables may be ventilation. PIP occurs early in the inspiratory phase employed with certain modes of ventilation. Examples during pressure-control ventilation and continues until of other trigger variables include preset apnea interval © Jones & theBartlett cycle variable Learning, criterion LLC is reached (e.g., time or flow© Jonesset as a& backup Bartlett safety Learning, feature in the LLC event of apnea, NOT FOR SALEcycle). Occasionally OR DISTRIBUTION an inspiratory pause or hold of 0.5 NOTand FOR electrical SALE signals OR fromDISTRIBUTION the diaphragm (see neurally to 1.5 seconds may be mechanically applied at the end adjusted ventilatory assist [NAVA]). Mandatory minute

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© Jones &volume Bartlett (MMV) Learning, ventilation LLC may automatically increase© Jonespressure & ventilationBartlett ,Learning, pressure-targeted LLC ventilation, and the respiratory rate (or pressure-support level, depend-NOTpressure-limited FOR SALE ORventilation DISTRIBUTION. NOT FOR SALEing on the OR ventilator DISTRIBUTION employed) to meet a minimum Pressure-support ventilation (PSV) is a form of minute ventilation goal. spontaneous ventilation (see definition below) in which The cycle variable refers to the method by which the beginning of inspiration is patient triggered and inspiration is cycled off or stops (i.e., the changeover the inspiratory pressure rapidly rises to a preset value. from inspiration to expiration).© Jones Common& Bartlett cycle Learning, vari- LLCWith PSV, the change over from© Jones inspiration & Bartlett to expira -Learning, LLC Pressure-control ventilation (PCV) ables include inspiratoryNOT time, FOR inspiratory SALE pressureOR DISTRIBUTION tion is flow cycledd. NOT FOR SALE OR DISTRIBUTION (i.e., peak airway pressure), volume, and flow (e.g., per- is the term employed for PC ventilation in which the centage of peak inspiratory flow). Thus, a breath may beginning of inspiration is time or patient triggered be volume cycled, pressure cycled, time cycled, or (aka assist-control) and the change over from inspira- flow cycled. It should also be noted that a breath may be tion to expiration is time cycled. pressure© Jones limited & and Bartlett pressure Learning, cycled, pressure LLC limited Although© the Jones term pressure-support& Bartlett Learning, ventilation LLC andNOT time cycledFOR (e.g.,SALE pressure-control OR DISTRIBUTION ventilation), or is commonlyNOT used, FOR it should SALE be notedOR DISTRIBUTION that the pressure limited and flow cycled (e.g., pressure-support recommended taxonomy for PSV is pressure ventilation), as described below. control-continuous spontaneous ventilation Volume control (VC) occurs when volume delivery is (PC-CSV).4,5 In a similar fashion, while the term fixed, and airway pressure varies with changes in resist- pressure-control ventilation is in common use, the ance and compliance. Put another way, with VC the preferred taxonomy for PCV is pressure control- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 4,5 NOT FOR SALEpreset tidal OR volume DISTRIBUTION is delivered regardless of patient NOTcontinuous FOR SALE mandatory OR DISTRIBUTION ventilation (PC-CMV). effort, resistance, or compliance and peak airway pres- This taxonomy is described further below. sure varies (assuming the ventilator’s set pressure limit Mandatory breaths occur when the ventilator de- is not reached). Other terms often used to refer to VC livers the same breath type with every cycle, regard- include volume ventilation, volume-targeted ventila- less of whether the breath is patient or time triggered 5 tion, and volume-limited© Jones ventilation. & Bartlett Both volume Learning, and LLCto inspiration. Mandatory breaths© Jones may & be Bartlett VC or PC Learning, LLC flow are preset priorNOT to inspiration FOR SALE during OR VC. DISTRIBUTIONIt should breaths. Terms sometimes usedNOT to FOR refer toSALE manda OR- DISTRIBUTION be noted that the targeting scheme employed refers tory breaths include machine breaths, or mechanical to the characteristics that distinguish the ventilatory breaths, although these terms are not recommended. pattern in use.4,5 For example, a volume-control mode Spontaneous breaths occur when the start and end in which the operator sets all parameters for volume of inspiration are determined by the patient, indepen- 5 and© flow Jones waveforms, & Bartlett is known Learning, asset-point LLC targeting. dent of other© ventilatorJones &settings. Bartlett Put Learning,another way, LLC A targetingNOT FOR scheme SALE that allowsOR DISTRIBUTION the ventilator to auto- during spontaneousNOT FOR breathing, SALE the OR patient DISTRIBUTION triggers the matically adjust pressure between breaths to achieve breath to inspiration and cycles the breath to expira- an average tidal volume over several breaths would be tion. Spontaneous breaths may or may not be pressure referred to as adaptive targeting (e.g., adaptive pres- supported (i.e., pressure-support ventilation) and may sure ventilation [APV] or pressure-regulated volume or may not occur with an elevated baseline pressure dual targeting © Jones & controlBartlett [PRVC]). Learning, With LLC , the ventilator © Jones(i.e., continuous & Bartlett positive Learning, airway pressure LLC or CPAP). can automatically switch between volume control and Some authors have suggested that if the ventilator does NOT FOR SALEpressure OR control DISTRIBUTION during a single breath. Other target- NOTsome FOR or SALE all the WOB, OR DISTRIBUTION the breath is assisted.5 Normal ing schemes include servo, optimal, biovariable, and spontaneous breathing is unassisted, while spontaneous intelligent targeting discussed below under modes of breathing with pressure support is assisted.5 The use of ventilation.4,5 the term assisted breathing in this context should not be Pressure control (PC)© Jones occurs when& Bartlett inspiratory Learning, air- LLCconfused with the term assist-control© Jones, which & Bartlett indicates Learning, LLC way pressure remains constant despite changes in pa- the trigger method. tient effort, resistanceNOT and FORcompliance. SALE With OR PC, DISTRIBUTION tidal Continuous spontaneous ventilationNOT FOR (CSV) SALE oc- OR DISTRIBUTION volume varies and is dependent on the driving pressure, curs when all breaths are initiated and ended by the inspiratory time, patient effort, compliance, resistance, patient.5 Common examples of CSV modes include and presence (or absence) of PEEP. Inspiratory pressure normal spontaneous breathing, PSV, and CPAP. Other is predetermined© Jones & Bartlettwith PC. It Learning, should be noted LLC that a PC forms of CSV© Jonesinclude automatic& Bartlett tube Learning, compensation LLC breath may be triggered by time or patient effort and cy- (ATC), proportional assist ventilation (PAV), and NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION4,5 cled to expiration by time (i.e., time-cycled ventilation) neurally adjusted ventilatory assist (NAVA). or flow (i.e., flow-cycled ventilation). It should be noted The term continuous mandatory ventilation that older ventilators (e.g., Bird Mark series) allowing (CMV) is used when every breath is a mandatory for pressure-cycled ventilation are no longer in common breath, regardless of whether the breath is patient or 4 © Jones & use,Bartlett although Learning, pressure-cycled LLC breath termination may © Jonestime triggered & Bartlett (aka Learning,assist-control). LLC CMV breaths pressure control-continuous mandatory NOT FOR SALEoccur if ORthe ventilator’s DISTRIBUTION set pressure limit is reached. NOTmay FOR be SALE OR DISTRIBUTION Other terms sometimes used to refer to PC include ventilation (PC-CMV) breaths or volume control-

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continuous mandatory ventilation (VC-CMV) © Jones & Bartlett Learning, LLC breaths. © JonesRC &Insight Bartlett Learning, LLC VC-CMV is commonly referred to as assist-control NOT FOR SALE OR DISTRIBUTION NOT FOR SALE(A/C) volume OR DISTRIBUTION ventilation. To add to the confusion, the Indications for NIV in the acute care setting in- terms controlled-volume ventilation or volume ventilation in the control mode are commonly used to refer to clude acute exacerbation of COPD with hypercap- time-triggered VC-CMV. These latter terms should be nic acidosis, cardiogenic pulmonary edema, and avoided in favor of time-triggered© Jones & VC-CMVBartlett. Learning, LLCacute hypoxemic respiratory© Jonesfailure. NIV & Bartlettmay also Learning, LLC Intermittent mandatory ventilation (IMV) be used to prevent extubation failure. NOT FOR SALE OR occurs DISTRIBUTION when NOT FOR SALE OR DISTRIBUTION patients can breathe spontaneously between mandatory breaths. Synchronized intermittent mandatory ventilation (SIMV) is a form of IMV in which the man- NIV is also commonly used to support ventilation datory breaths may be time or patient triggered. With in patients with chronic hypoventilation due to neuromuscular or chest wall disease (e.g., muscular dys- SIMV,© Jones spontaneous & Bartlett breaths may Learning, be pressure LLC supported © Jones & Bartlett Learning, LLC (i.e., SIMV with pressure support). SIMV may also be trophy, post-polio syndrome, other slowly progressing NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION8 provided with (or without) an elevated baseline pres- neuromuscular diseases, or chest wall deformity). Such sure (i.e., PEEP/CPAP). Note the term IMV has been patients may be candidates for nocturnal or sustained suggested for mode classification purposes regardless NIV, especially if they have either daytime hypercapnia or nocturnal hypoventilation with sustained oxygen whether intermittent mandatory breaths are time or 8 patient triggered.4,5 That said, the term SIMV remains desaturation. © Jones & Bartlett Learning, LLC © JonesContraindications & Bartlett Learning, for NIV include LLC cardiac or respi- NOT FOR SALEin common OR use DISTRIBUTION by both clinicians and manufacturers. NOT FOR SALE OR DISTRIBUTION Table 6-1 summarizes terminology in use to describe ratory arrest; hemodynamic or cardiac instability (e.g., common modes of ventilation. Box 6-1 lists additional unstable cardiac arrhythmias), or severely impaired < 6 modes available on certain ventilators. consciousness (Glasgow coma score [GCS] 10). NIV may also be contraindicated in the presence of Noninvasive Ventilation facial trauma, facial surgery, or facial deformity. Upper © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC airway obstruction, inability to protect the airway or Noninvasive ventilation (NIV) refers to techniques that NOT FOR SALE OR DISTRIBUTIONclear secretions, and high riskNOT for aspiration FOR SALE are rela- OR DISTRIBUTION do not require insertion of an invasive artificial airway tive contraindications for the use of NIV. For example, (e.g., endotracheal intubation or tracheostomy). NPPV patients with upper gastrointestinal bleeds are not good is the most common form of NIV in use today. CPAP candidates for NIV. Patients with acute respiratory and bilevel positive airway pressure (BiPAP) have been failure who are likely to require prolonged mechanical used© inJones the home & Bartlettfor management Learning, of obstructive LLC sleep © Jones & Bartlett Learning, LLC ventilatory support may be best treated with invasive apnea (OSA) for many years. BiPAP combines inspira- NOT FOR SALE OR DISTRIBUTION mechanicalNOT ventilation. FOR Patients SALE with OR encephalopathy DISTRIBUTION tory positive airway pressure (IPAP) and expiratory (i.e., brain dysfunction) caused by hypercapnia may positive airway pressure (EPAP). The routine use of NIV respond to NIV, but these patients must be carefully for patients with acute respiratory failure has been a monitored; if there is no prompt response, intubation relatively recent development. and invasive mechanical ventilation should occur.6 NIV NIV requires the use of a nasal mask, oronasal © Jones & Bartlett Learning, LLC © Jonescan result & Bartlett in gastric Learning,inflation at pressures LLC above 20 to mask, nasal pillows, mouthpiece, or helmet interface. NOT FOR SALE OR DISTRIBUTION NOT25 FOR cm H SALEO; NIV OR is also DISTRIBUTION contraindicated in patients who Properly applying the interface to avoid excessive leaks 2 have recently received esophageal surgery or in the without causing patient discomfort or skin break- presence of a tracheal-esophageal fistula.6 NIV may be down is one of the more important and challenging provided using BiPAP, PSV, assist-control (A/C) volume aspects of NIV. The oronasal or full-face mask is the ventilation (aka VC-CMV), PAV, and NAVA. Initial NIV most common interface for use in patients with acute © Jones & Bartlett Learning, LLCventilator settings using BiPAP,© PSV,Jones or volume & Bartlett ventila- Learning, LLC respiratory failure. NIV may be delivered by volume- NOT FOR SALE OR DISTRIBUTIONtion typically include:6,8 NOT FOR SALE OR DISTRIBUTION limited or pressure-limited ventilators. Most BiPAP devices are flow triggered to inspiration, flow cycled ■■ Lower initial pressures for BiPAP and PSV to to expiration, and pressure limited. Newer critical care allow for patient adaptation to the device and ventilators may also have an NIV mode built in. interface. ●● ©Indications Jones for& BartlettNIV include Learning, acute exacerbation LLC of IPAP© Jones8 to 20 cm & HBartlett2O (begin Learning,at 8 to 12 cm LLCH2O COPD with hypercapnic acidosis, cardiogenic pulmo- for most patients). NOT FOR SALE OR DISTRIBUTION 6 ●● NOT FOR SALE OR DISTRIBUTION nary edema, and acute hypoxemic respiratory failure. EPAP 3 to 5 cm H2O. NIV may also be useful to prevent postextubation res- ●● Delta P (∆P = IPAP – EPAP) should be ad- piratory failure. Nocturnal NIV may be useful for stable justed to about 5 to 15 cm H2O to ensure ad- COPD patients with chronic respiratory failure and day- equate tidal volume. © Jones & timeBartlett hypercapnia. Learning, NIV may LLC also be useful for acute or © Jones ●&● IPAPBartlett should Learning, be maintained LLC < 25 to 30 cm NOT FOR SALEimpending OR respiratory DISTRIBUTION failure in pediatric patients whoNOT FOR SALEH2O in orderOR DISTRIBUTION to avoid gastric insufflation and do not require emergency endotracheal intubation.7 ventilator-induced lung injury.

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© Jones & Bartlett Learning, expiration to inspiration is patient or time Changeover from mode). (i.e., assist-control triggered wave Inspiratory flow waveform may be adjustable (e.g., square or down ramp); waveform does not vary during inspiration. inspiration to expiration is volume cycled (or Changeover from LLCtime cycled but volume is constant based on flow and time). Expiratory phase allows for the application of PEEP. (i.e., expiration to inspiration is time triggered Changeover from mode). control wave Inspiratory flow waveform may be adjustable (e.g., square or down ramp); waveform does not vary during inspiration. inspiration to expiration is volume cycled (or Changeover from time cycled but volume constant based on flow and time). Expiratory phase allows for the application of PEEP. © Jones expiration to inspiration is patient or time trig- Changeover from If the trigger variable is mode or PAC). (i.e., assist-control gered mode. to as control time, this is commonly referred limited. Inspiration is pressure & or decelerating. Inspiratory flow waveform is decreasing Bartlett inspiration to expiration is time cycled. Changeover from Expiratory phase allows for the application of PEEP. Learning, expiration to inspiration is patient or time Changeover from triggered. may be Inspiratory flow waveform for VC mandatory breaths LLC wave or down ramp) and waveform does adjustable (e.g., square not vary during mandatory breaths. inspiration to expiration is volume cycled (or Changeover from time cycled but volume constant based on flow and time). Expiratory phase allows for the application of PEEP. may be ambient or elevated (CPAP). Baseline pressure support (PSV) may be added for spontaneous breaths. Pressure lim- pressure support is patient triggered, Inspiratory pressure ited, and flow cycled. NOT FOR SALE OR mandatory: are All breaths DISTRIBUTION• • • • mandatory: are All breaths • • • • NOT mandatory: are All breaths • FOR• • SALE• • OR DISTRIBUTIONMandatory breaths: • • • • Spontaneous breaths: • • •

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Volume assist-control (VA/C) assist-control Volume ventilation A/C Volume-limited ventilation (A/C) Volume-cycled volume control Assist-control (A/C VC) controlled Synchronized mandatory ventilation (S)CMV CMV mechanical Controlled ventilation ventilation: Volume-limited mode control (PC): control Pressure to sometimes used to refer time cycled time-triggered, ventilation pressure-control some- assist (PA): Pressure to patient- times used to refer pressure-control triggered ventilation limited: time-cycled Pressure A/C mandatory Pressure-control ventilation (P-CMV) SIMV (volume control) with pres- SIMV volume control support sure SIMV Volume-targeted SIMV Volume-limited SIMV Alternative Terminology Description • • • • • • • • • • • • • • • • • © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 1–6

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Volume A/C or VAC Volume (A/C) volume ventilation Assist-control ventilation assist- Volume-control mode (VC AC) control A/C ventilation Volume-targeted or VC control Volume mode volume ventilation Control ventilation: control Volume-targeted mode or PAC assist-control Pressure ventilation (PCV) Pressure-control ventilation Pressure-targeted control A/C pressure CMV Pressure-control SIMV or V-SIMV Volume intermittent mandatory Synchronized ventilation (SIMV) SIMV (VC) Common Terminology • • • • • • • • • • • • • • • © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Volume Control-Continuous Mandatory Control-Continuous Volume (VC-CMV): patient or time Ventilation triggered. mandatory and may be are Note: all breaths or time triggered. patient triggered Volume Control-Continuous Mandatory Control-Continuous Volume (VC-CMV): time triggered Ventilation mandatory and time are Note: all breaths triggered. Mandatory Control-Continuous Pressure (PC-CMV) Ventilation mandatory and may be are Note: all breaths or time triggered. patient triggered Intermittent Mandatory Control Volume (VC-IMV) Ventilation interspersed with are Note: mandatory breaths may Mandatory breaths spontaneous breaths. (i.e., SIMV). Spon- be patient or time triggered augmented may be pressure taneous breaths support or automatic tube com- (e.g., pressure pensation [ATC]) Preferred Taxonomy Preferred NOT FOR SALE 6-1 TABLE Used to Describe Modes of Ventilation Terminology OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, expiration to inspiration is patient or time Changeover from triggered. limited. Inspiration is pressure or Inspiratory flow waveform is decreasing LLCdecelerating. inspiration to expiration is Changeover from time cycled. Expiratory phase allows for the application of PEEP. may be ambient or elevated (CPAP). Baseline pressure during inspiration support (PSV) may be provided Pressure for spontaneous breaths. pressure support is patient triggered, Inspiratory pressure limited, and flow cycled. © flow-cycled pressure-limited, Patient-triggered, Jonesventilation. may be ambient or elevated (CPAP). Baseline pressure during inspiration for support provided Pressure spontaneous breaths. & support is patient triggered. Inspiratory pressure Bartlett inspiration to expiration is Changeover from flow cycled. Learning, LLC NOT FOR SALE OR DISTRIBUTION: Mandatory IMV breaths • • • • • : Spontaneous breaths • • • Spontaneous breaths: NOT• • FOR• • SALE• OR DISTRIBUTION

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION SIMV pressure control SIMV pressure (P-SIMV) Pressure-SIMV inter- synchronized Pressure mittent mandatory ventilation (P-SIMV) SIMV Pressure-limited SIMV Pressure-targeted with control SIMV pressure support pressure support (PS) Pressure support Spontaneous pressure support Standalone pressure Alternative Terminology Description • • • • • • • • • © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ol (VAC); pressure assist-control (PAC); volume-synchronized intermittent mandatory ventilation (V-SIMV); pressure- volume-synchronized (PAC); assist-control pressure ol (VAC); 1–6

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Pressure-control SIMV or P-SIMV Pressure-control control SIMV pressure SIMV (PC) Pressure-support ventilation or PSV Pressure-support Common Terminology • • • © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION t. ol.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,e assist. LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION synchronized intermittent mandatory ventilation (P-SIMV); and pressure-support ventilation (PSV). intermittent mandatory ventilation (P-SIMV); and pressure-support synchronized © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC volume assist-contr are Modes available using this simplified nomenclature 1. AC (or A/C) indicates assist-control, which may be time or patient triggered. which may be time or patient triggered. 1. AC (or A/C) indicates assist-control, 2. VC indicates volume control. contr 3. PC indicates pressure indicates pressur 4. PA suppor 5. PS indicates pressure 6. Pressure Control Intermittent Mandatory Control Pressure (PC-IMV) Ventilation interspersed with are Note: mandatory breaths may Mandatory breaths spontaneous breaths. Spon- or time triggered. be patient triggered augmented may be pressure taneous breaths support or automatic tube com- (e.g., pressure pensation [ATC]) Pressure Control-Continuous Spontaneous Control-Continuous Pressure (PC-CSV) Ventilation or volume controlled and pressure may be time or patient triggered Mandatory breaths type with every breath. occur when the ventilator delivers same breath Mandatory breaths to is commonly used to refer breaths In a similar fashion, the term control patient triggered. that are to PC or VC breaths is commonly used to refer (PC or VC). The term assisted breath to as continuous mandatory ventilation (CMV). CMV may be volume or pressure the mode is referred is a mandatory breath, When every breath time triggered. that are PC or VC breaths support (PS) or initiated by the patient and determines when end of inspiration occurs (i.e., cycled). Pressure are (VC-CMV or PC-CMV). Spontaneous breaths controlled control-continuous and support some of the work inspiration. When used alone, PSV is a form pressure may be applied during spontaneous breaths automatic tube compensation (ATC) spontaneous ventilation (PC-CSV). continuous positive airway pressure. CPAP, positive end-expiratory pressure; PEEP, Preferred Taxonomy Preferred TABLE 6-1 TABLE ( Continued ) Used to Describe Modes of Ventilation Terminology

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC © Jones & BartlettBox 6-1 Learning, Other Availabl LLCe Modes of Ventilation NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Noninvasive ventilation (NIV) is sometimes referred and eVent Inspiration 7i (eVent Medical, Lake to as noninvasive positive-pressure ventilation Forest, CA). (NPPV). yyOther proprietary names for PRVC include Auto- yyThe ventilator is connected to the patient using flow (Dräger Evita E-4, Infinity V500 Elite), VC+ © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC a nasal mask or pillows, full face mask, mouth- (Covidien PB 840, PB 980) and adaptive pressure piece, or helmetNOT interface. FOR SALE OR DISTRIBUTIONventilation (Hamilton G5NOT and FOR G3). SALE OR DISTRIBUTION yyThe ventilator is typically patient triggered, pres- Volume support (VS). sure limited, and flow cycled. yyLike pressure support, breaths are patient trig- yyNIV is currently available on most critical care gered and flow cycled. The pressure-support © Jonesventilators. & Bartlett Learning, LLC level is© adjusted Jones automatically & Bartlett breath Learning, to breath LLC NOTBi-level FOR positive SALE airway OR pressure DISTRIBUTION (BiPAP). to achieveNOT a volume FOR SALEtarget. OR DISTRIBUTION yyOften used to deliver noninvasive ventilation, Bi- yyInspiration is patient triggered; spontaneous PAP delivers a preset inspiratory pressure (IPAP) breathing is required. that is patient triggered to inspiration and yyVS is a form of adaptive pressure control (see © Jones & Bartlettflow Learning, cycled to expiration LLC similar to pressure © Jonesbelow). & Bartlett Learning, LLC NOT FOR SALE supportOR DISTRIBUTION (PSV). NOT FORAdaptive SALE pressure OR control DISTRIBUTION (APC) automatically yyInspiratory positive airway pressure (IPAP) refers adjusts pressure control or pressure support to to the pressure delivered during inspiration. achieve the target tidal volume. yyExpiratory positive airway pressure (EPAP) re- yyInspiratory pressure varies automatically between fers to the baseline© Jones pressure & Bartlett maintained Learning, during LLCbreaths to achieve the target© Jones tidal volume. & Bartlett Learning, LLC expiration. NOT FOR SALE OR DISTRIBUTIONyyMaintains tidal volume withNOT changes FOR inSALE ventila- OR DISTRIBUTION yyAlong with compliance, resistance, and patient tory mechanics. effort, the difference between IPAP and EPAP de- yyMay improve patient–ventilator synchrony due termines the tidal volume delivered. to variable inspiratory flow provided. © Pressure-controlJones & Bartlett inverse-ratio Learning, ventilation LLC (PC-IRV). yyAPC is© also Jones known &as BartlettPRVC (Servo-i, Learning, Servo-u), LLC NOTyyTypically, FOR SALE the ventilator OR DISTRIBUTION is time triggered, pres- adaptiveNOT pressur FORe ventilation SALE OR (Hamilton DISTRIBUTION sure limited, and time cycled in a manner such Galileo), AutoFlow (Dräger), volume control plus that inspiration is longer than expiration (I:E (Puritan Bennett), and volume-targeted pressure ratio > 1:1; e.g., 1.5:1, 2:1). control (General Electric). yyInverse-ratio ventilation (IRV) increases mean yySupport is reduced if the patient’s tidal volume © Jones & Bartlettairway Learning, pressure and LLC may improve oxygenation ©in Jonesconsistently & Bartlett exceeds Learning, the target. LLC NOT FOR SALE certainOR DISTRIBUTION patients (e.g., severe ARDS). NOT FORAdaptive SALE support OR ventilation DISTRIBUTION (ASV) makes automatic Pressure-regulated volume control (PRVC). adjustments in respiratory rate and inspiratory yyPRVC is a form of adaptive pressure control pressure based on measurements of respiratory (see below). mechanics to deliver the desired minute ventilation yyProvides a volume-targeted,© Jones & Bartlett pressure-control Learning, LLCand minimize the WOB. © Jones & Bartlett Learning, LLC breath. NOT FOR SALE OR DISTRIBUTIONyyDesired minute ventilationNOT is calculated FOR SALE based OR DISTRIBUTION yyInspiration is patient or time triggered, pressure on the patient’s ideal body weight and estimated limited, and time cycled. Pressure is automati- dead space where target V˙ e = 0.1 L/min/kg or cally adjusted breath to breath to achieve a vol- 100 mL/min/kg. © Jonesume target. & Bartlett Learning, LLC yyThe level© ofJones ventilatory & Bartlett support to Learning, be provided is LLC ˙ NOTyyDelivered FOR SALE tidal volume OR DISTRIBUTION is measured and com- set by NOTthe clinician FOR as SALE a percentage OR ofDISTRIBUTION the target Ve. pared to the set (targeted) tidal volume; pres- yyThe ventilator uses an algorithm to determine sure control is gradually increased or decreased optimal breathing frequency (f) and a target tidal until the target tidal volume is reached. volume is calculated based on V˙ e and f (Vt = V˙ e/f) yyPressure control is then adjusted automatically © Jones & BartlettyyPRVC Learning, is available underLLC that name on the Ma- © Jones & Bartlett Learning, LLC quet Servo-i and Servo-u; Yvaire AVEA and VELA; to achieve the targeted tidal volume. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (Continues)

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© Jones & Bartlett Learning, LLC © Jones & BartlettBox 6-1 Learning, Other Available LLC Modes of Ventilation (Continued) NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Airway pressure-release ventilation (APRV). yyPAV may be more comfortable for some patients yyAPRV provides two levels of CPAP, which are and improves patient–ventilator synchrony by time triggered and time cycled. APRV allows for matching the patient’s inspiratory demand. spontaneous© breathing Jones at& both Bartlett levels. Learning, LLCyyPAV has not been shown© to Jones improve & patient Bartlett Learning, LLC outcomes. yyAPRV is typicallyNOT used FOR as a SALE form of ORpressure- DISTRIBUTION NOT FOR SALE OR DISTRIBUTION control inverse-ratio ventilation (PCIRV) in which Neurally adjusted ventilatory assist (NAVA) uses the high-pressure time exceeds the low-pressure the electrical discharge from the diaphragm (i.e., time. electromyography [EMG]) to trigger and cycle yyAPRV may reduce shunt and improve oxy- mechanical breaths. © Jonesgenation & andBartlett gas exchange Learning, as compared LLC to yyNAVA requires© Jones an esophageal & Bartlett catheter Learning, that incor LLC- NOTconventional FOR SALE ventilation OR DISTRIBUTION in ARDS patients; im- poratesNOT a multiple FOR array SALE esophageal OR DISTRIBUTION electrode. proved patient outcomes have not been clearly yyNAVA increases ventilator pressure as patient demonstrated. effort increases. Automatic tube compensation (ATC). yyNAVA may improve patient–ventilator synchrony. © Jones & BartlettyyImposed Learning, airway resistance LLC due to the endotra-© JonesMandatory & Bartlett minute Learning, volume ventilation LLC (MMV) is aka NOT FOR SALE chealOR DISTRIBUTION tube or tracheostomy tube is estimated. NOT FORmandatory SALE minute OR ventilationDISTRIBUTION, minimum minute yyPressure-support level is automatically adjusted ventilation, or augmented minute ventilation). to compensate for the WOBI. yyDesigned to promote ventilator weaning. yyThe clinician may choose 100% tube compensa- yyA minimum minute ventilation (V˙ e) is set for tion or a lower© value.Jones & Bartlett Learning, LLCspontaneously breathing© patients. Jones & Bartlett Learning, LLC Proportional assistNOT ventilation FOR SALE(PAV). OR DISTRIBUTIONyyThe ventilator monitorsNOT the patient’s FOR SALEsponta- OR DISTRIBUTION yyPAV incorporates an algorithm to calculate the neous minute volume and provides additional pressure required to ventilate based on the pa- ventilatory support as needed to achieve the set tient’s tidal volume, elastance, resistance, and minimal minute volume. © Jonesgas flow. & Bartlett Learning, LLC yyWith increased© Jones spontaneous & Bartlett V˙ e ,Learning, the ventilator LLC NOT FORThe ventilator SALE ORestimates DISTRIBUTION WOB based on in- reducesNOT the level FOR of supportSALE provided.OR DISTRIBUTION spiratory flow, volume, pressure, compliance, yyAdditional ventilatory support may be in the resistance, and pressure. form of increased pressure support or increased yyBreaths are patient triggered, pressure limited, IMV rate, depending on the ventilator employed. yyMMV using automatic adjustments in SIMV rate © Jones & Bartlettand Learning, flow cycled. LLC © Jones & Bartlett Learning, LLC can vary the number of mandatory breaths from NOT FOR SALEyy Pressure,OR DISTRIBUTION flow, and volume are proportional toNOT FOR SALE OR DISTRIBUTION the patient’s spontaneous effort and clinician- 0 to the set SIMV rate, depending on the pa- set parameters. tient’s spontaneous V˙ e. Pressure varies depending on the amount of High-frequency ventilation (HFV) delivers small tidal inspiratory flow and volume demanded by the volumes at a very high respiratory frequency. Pos- patient and© theJones amplification & Bartlett level Learning,selected LLCsible indications for HFV include© Jones ARDS, bronchopleu& Bartlett- Learning, LLC by the clinician.NOT FOR SALE OR DISTRIBUTIONral fistula, and air leaks. HFVNOT is not FOR recommended SALE ORas DISTRIBUTION a first choice for mode of ventilation and should be Flow increases proportionally as patient’s in- avoided in patients with obstructive lung disease. spiratory effort increases. yyHigh-frequency oscillatory ventilation (HFOV) is yyThe clinician adjusts the percentage of support delivered using an oscillator to provide a respira- © Jones(from 5%& Bartlettto 95%) to Learning, achieve WOB LLC in the range © Jones & Bartlett Learning, LLC tory frequency in the range of 3 to 15 Hz (180 to NOTof FOR 0.5 to SALE 1.0 joules OR per DISTRIBUTION liter. NOT FOR SALE OR DISTRIBUTION 900 breaths/min). yyApplied pressure and inspiratory time vary HFOV may minimize alveolar over distention breath by breath and within each breath depend- and derecruitment. ing on changes in compliance, resistance, and © Jones & Bartlettflow Learning, demand. Inspiratory LLC time is determined by© Jones &HFOV Bartlett seems Learning, to be effective LLC in neonatal respiratory failure. NOT FOR SALE theOR flow DISTRIBUTION cycle setting. NOT FOR SALE OR DISTRIBUTION

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© Jones & BartlettHFOV Learning, may be consideredLLC for refractory © JonesyyHigh-frequency & Bartlett Learning, positive-pressure LLC ventilation NOT FOR SALE ORhypoxemic DISTRIBUTION respiratory failure in adults, al- NOT FOR(HFPPV) SALE uses OR a conventional DISTRIBUTION ventilator with a though better patient outcomes have not low tidal volume setting and a very rapid respira- been demonstrated. tory rate. yyHigh-frequency jet ventilation (HFJV) is delivered Continuous positive airway pressure (CPAP). using a jet gas© flowJones delivered & Bartlett to the endotra- Learning, LLCyyCPAP allows for spontaneous© Jones breathing & Bartlett at el- Learning, LLC cheal tube viaNOT a small FOR cannula. SALE OR DISTRIBUTIONevated baseline pressure.NOT FOR SALE OR DISTRIBUTION yyHigh-frequency percussive ventilation (HFPV) yyCPAP increases functional residual capacity combines time-cycled pressure-control ventila- (FRC) and may improve compliance, oxygen- tion with a phasitron to provide oscillatory or ation, and ventilation in patients with acute re- © Jonespercussive & Bartlett ventilation Learning, throughout inspirationLLC strictive© lung Jones disease. & Bartlett Learning, LLC and expiration. HFPV may improve secretion NOT FOR SALE OR DISTRIBUTION WOBI - imposedNOT work of FOR breathing SALE OR DISTRIBUTION clearance, improve oxygenation and ventilation, and lower airway pressures.

© Jones & Bartlett■■ For volume Learning, ventilation, LLC larger initial tidal volumes© Jonessupport & probablyBartlett are Learning, best served byLLC invasive mechan- NOT FOR SALEof OR6 to 10DISTRIBUTION mL/kg have been suggested to compen-NOTical FOR ventilation. SALE TheOR placementDISTRIBUTION of an endotracheal tube sate for air leaks during NIV. or tracheostomy tube may also facilitate suctioning of ■■ Trigger effort should be set for minimal patient airway secretions. work without autocycling. ■■ A backup respiratory rate may be set 2 to 4 RC Insight breaths/min below© Jones the patient’s & Bartlett spontaneous Learning, rate. LLC © Jones & Bartlett Learning, LLC Patients often initiallyNOT FOR hyperventilate, SALE OR and DISTRIBUTIONthe Invasive ventilation has theNOT advantage FOR of SALE securing OR DISTRIBUTION backup rate may be adjusted accordingly. Patients’ and protecting the airway and providing a more rates may slow within 6 to 12 hours as they dependable form of ventilatory support for un- become accustomed to NIV, and the backup rate stable, critically ill patients. may need to be decreased at that time. ■■ © JonesInitial Fio &2 shouldBartlett be selected Learning, to avoid LLC hypox- © Jones & Bartlett Learning, LLC NOTemia FOR without SALE administration OR DISTRIBUTION of excessive oxygen EstablishmentNOT FOR of SALE the AirwayOR DISTRIBUTION concentrations. Nasopharyngeal or oral pharyngeal airways may be Following initial ventilator setup, the ventilator is helpful in certain patients with soft tissue obstruction; adjusted to ensure adequate oxygenation, ventilation, however, they do little to protect the lower airway and © Jones & andBartlett patient Learning,comfort while LLC avoiding patient–ventilator © Jonesdo not & allow Bartlett for invasive Learning, mechanical LLC ventilatory sup- asynchrony. Chapter 10 provides additional information port. Extraglottic airways (aka supraglottic airways) NOT FOR SALEregarding OR NIV. DISTRIBUTION NOThave FOR been SALE sometimes OR DISTRIBUTIONused during general anesthesia or as an adjunct to manage difficult and emergency air- Invasive Ventilation ways.9 An example of an extraglottic airway is the laryn- Invasive mechanical ventilation is provided via an geal mask airway (LMA). artificial airway whose© Jonestip is located & Bartlett in the trachea Learning, LLCMost patients requiring invasive© Jones mechanical & Bartlett venti- Learning, LLC (e.g., endotracheal tube or tracheostomy tube). lation, however, are endotracheally intubated, and Invasive ventilation hasNOT the advantageFOR SALE of securing OR DISTRIBUTION and the clear majority (95%) of theseNOT intubations FOR SALE are done OR DISTRIBUTION protecting the airway and providing a more dependable orally; the remaining endotracheal tubes are placed na- form of ventilatory support for unstable, critically ill sally. A subset of patients requiring extended invasive patients. For example, in patients requiring mechan- mechanical ventilation will receive a tracheostomy at ical© ventilatory Jones & support, Bartlett the lossLearning, of protective LLC airway some point© (most Jones often & > Bartlett10 to 14 days, Learning, but earlier LLC in reflexesNOT areFOR an important SALE OR indication DISTRIBUTION for endotracheal some patients).NOT FOR SALE OR DISTRIBUTION intubation. On the other hand, patients who can swal- Endotracheal Intubation low and speak may not require endotracheal intubation to protect the lower airway; these patients may be can- Indications for endotracheal intubation include the in- didates for NIV. Patients with depressed mental status ability to maintain a patent airway, inability to protect © Jones & (e.g.,Bartlett unconsciousness, Learning, coma), LLC hemodynamic instability,© Jonesthe airway & Bartlett against aspiration, Learning, failure LLC to ventilate, failure severe oxygenation disorders, and those requiring (or to oxygenate, and anticipation of deterioration in the NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 10 likely to require) sophisticated mechanical ventilatory patient’s condition that will lead to respiratory failure.

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© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-2 Learning, Indications, LLC Contraindications, and Complications of Endotracheal Intubation NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Indications yySecretions Cardiac arrest yyKinks Apnea (e.g., respiratory arrest) yyCuff leaks Upper airway obstruction© Jones & Bartlett Learning, LLCyyPilot balloon failure © Jones & Bartlett Learning, LLC Need to provideNOT a patent FOR airway SALE (e.g., OR coma, DISTRIBUTION de- yyAspiration of secretionsNOT due to FOR cuff failure SALE or OR DISTRIBUTION pressed mental status) improper inflation Need to protect the airway (e.g., high risk of aspira- Complications associated with suctioning tion, lack of gag reflex) yyHypoxemia ©Respiratory Jones & failure Bartlett (failure Learning, to oxygenate LLC and/or yyArrhythmias© Jones & Bartlett Learning, LLC ventilate) NOT FOR SALE OR DISTRIBUTION yyVagal stimulationNOT FOR SALE OR DISTRIBUTION Need to provide mechanical ventilatory support to yyBradycardia critically ill patients (i.e., invasive mechanical ventilation; NIV contraindicated or impractical) yyHypotension Anticipated deterioration in the patient’s condition yyCardiac arrest © Jones & Bartlettthat will Learning, lead to respiratory LLC failure © JonesVentilator-associated & Bartlett Learning, pneumonia LLC (VAP) NOT FOR SALE OR DISTRIBUTION NOT FORTracheobronchitis SALE OR DISTRIBUTION Contraindications Supraglottic or subglottic pathology (e.g., blunt Nasal complications (due to nasal endotracheal trauma with laryngeal fracture) intubation) Penetrating trauma of the upper airway (e.g., he- yySinusitis due to impaired sinus drainage matoma, airway© transection) Jones & Bartlett Learning, LLCyyNasal necrosis (following© nasal Jones intubation) & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Severe laryngeal edema or supralaryngeal edema Laryngeal injury due to ETT (e.g., anaphylaxis, bacterial infection, or burns) yyVocal cord ulceration Difficult airway due to anatomic features or yyGlottic edema injuries yySubglottic edema © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC yyVocal cord ulceration ComplicationsNOT FOR SALE During OR the ProcedureDISTRIBUTION NOT FOR SALE OR DISTRIBUTION Difficult intubation may result in complications yyVocal cord paralysis Prolonged intubation attempts yyLaryngeal inflammation Hypoxemia, hypercarbia, and acidosis yyGranuloma formation Trauma to the upper airway yyLaryngotracheal stenosis © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Glottis, vocal cord, or laryngeal trauma Tracheomalacia NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Aspiration of stomach contents (patient may gag Tracheal arterial fistula and vomit) Tracheoesophageal fistula Inadvertent mainstem bronchial intubation Complications discovered following extubation Inadvertent esophageal© Jones intubation & Bartlett Learning, LLCyySwallowing disorders © Jones & Bartlett Learning, LLC Airway obstructionNOT FOR SALE OR DISTRIBUTIONyyHoarseness NOT FOR SALE OR DISTRIBUTION Complications Following the Procedure yySore throat Accidental extubation yySpeech impairment Airway malfunction yyTracheal stenosis © yJonesyObstruction & Bartlett Learning, LLC yyExtubation© Jones failure &requiring Bartlett re-intubation Learning, or NIV LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Contraindications to endotracheal intubation generally are summarizes indications, contraindications, and hazards those in which the procedure for tube insertion is likely associated with endotracheal intubation. to cause additional airway trauma or is likely to be unsuc- Rapid-sequence intubation (RSI) is performed for © Jones & cessful.Bartlett NIV Learning, may be helpful LLC in such situations, although an© Jonesemergency & Bartlett airway management. Learning, Completion LLC of RSI NOT FOR SALEemergency OR tracheostomy DISTRIBUTION (or in rare cases cricothyrotomy)NOT includes FOR SALE the administration OR DISTRIBUTION of an induction agent (e.g., may be necessary if ventilation is compromised. Box 6-2 ketamine [Ketalar], etomidate [Amidate], midazolam

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© Jones &[Versed], Bartlett and Learning, propofol [Diprivan]) LLC resulting in uncon- © JonesClass & IBartlett: Visible structures Learning, include LLC the tongue, hard sciousness immediately followed by a paralytic agent NOT FORpalate, SALE soft OR palate, DISTRIBUTION uvula, and posterior pharynx. NOT FOR SALE(e.g., rocuronium OR DISTRIBUTION [Zemuron], succinylcholine [Anec- Class II: Visible structures include the tongue, hard tine]) for neuromuscular blockade.10 Initial medication palate, soft palate, and part of the uvula, and pos- dosage is based on the patient’s weight and designed to terior pharynx. achieve unconsciousness and paralysis within 1 min- Class III: Visible structures include the tongue, hard 10 ute. Induction and ©paralysis Jones may & notBartlett be necessary Learning, in LLC palate, soft palate; posterior© Jones pharynx & NOTBartlett visible. Learning, LLC already unconsciousNOT and apneic FOR patients SALE (e.g., OR a DISTRIBUTIONcrash Class IV: Visible structuresNOT include FOR only SALE the anterior OR DISTRIBUTION airway). Specific indications for emergency endotra- tongue and hard palate. cheal intubation include cardiac arrest, respiratory Portable chest x-rays taken shortly after intubation are arrest, and upper airway obstruction not relieved by often useful in confirming proper tube placement. The tip other methods. of the endotracheal tube generally should lie in the middle Direct laryngoscopy is often employed to achieve © Jones & Bartlett Learning, LLC one-third of© the Jones trachea and& Bartlett be at least Learning,2 cm above the LLC endotracheal intubation. Prior to intubation, the pa- NOT FOR SALE OR DISTRIBUTION carina. FollowingNOT tube FOR placement, SALE bedside OR DISTRIBUTION ultrasound may tient is assessed and the appropriate equipment, sup- be useful to confirm bilateral lung ventilation by observing plies, and medications are gathered.9,11 The patient is the lung sliding sign on each side (i.e., movement of the prepared, positioned, and preoxygenated with 100% parietal and visceral pleura as the lung expands and con- oxygen using a bag-valve mask system with a PEEP tracts).11 If the lung sliding sign is present on only one side, valve.9,11 For oral intubation, the patient’s mouth is © Jones & Bartlett Learning, LLC © Jonesbronchial & Bartlett intubation Learning,may have occurred. LLC Absence of slid- opened and the laryngoscope is introduced and ad- NOT FOR SALE OR DISTRIBUTION NOTing FOR is also SALE seen with OR a pneumothoraxDISTRIBUTION or scarring between vanced until the epiglottis and glottis can be visualized. the visceral and parietal pleura. Box 6-3 summarizes key The endotracheal tube is then guided to the glottis points regarding endotracheal intubation. Chapter 9 pro- and inserted between and past the vocal cords into vides additional information regarding patient assessment the trachea. Recent advances in intubation include the and the procedure for endotracheal intubation. common use of a video© Jones laryngoscope & Bartlett (e.g., the Learning, Glide LLC © Jones & Bartlett Learning, LLC Scope), where the entireNOT glottis FOR can SALE be visualized OR DISTRIBUTION from NOT FOR SALE OR DISTRIBUTION the level of the pharynx and a specialized stylet allows RC Insight the ET tube to be placed past the level of the vocal cords. Following insertion to an appropriate depth (e.g., Endotracheal intubation can maintain a patent 21 cm for most adult females or 23 cm for most adult airway, protect the airway against aspiration, and males)© Jones the tube & is Bartlettsecured, and Learning, the patient LLC is mechani- allow for ©ventilation Jones &and Bartlett oxygenation. Learning, LLC cally supported using the manual resuscitator bag and NOT FOR9,11 SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 100% oxygen. Equal and bilateral breath sounds Tracheostomy should be confirmed by auscultating the patient’s chest and assessment for the presence of exhaled CO2 using Indications for tracheostomy include long-term mech- capnography should be promptly performed to confirm anical ventilation, weaning failure, upper airway obstruc- 9,11 12 © Jones & properBartlett tube Learning, placement. LLC Once proper placement of © Jonestion, and & Bartlettfor the management Learning, of copious LLC secretions. A the endotracheal tube has been assured and the tube surgical tracheostomy is performed in the region of the NOT FOR SALEsecured, OR mechanical DISTRIBUTION ventilation can begin. Figure 6-1 NOTsecond FOR toSALE fourth ORtracheal DISTRIBUTION cartilages, while percutaneous describes assessment of the difficult airway. The tracheostomy is done between the first and second or modified Mallampati Classification system for airway the second and third tracheal cartilages.13 Percutaneous assessment is described below. tracheostomy is simpler, quicker, and has a lower rate of © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Class I Class II Class III Class IV © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 6-1 Modified Mallampati Classification. The modified Mallampati difficulty classification is based on structures visible during NOT FOR SALEoropharyngeal OR examination DISTRIBUTION via direct laryngoscopy. Class I is least difficultNOT intubation, FOR SALE while Class OR IV is DISTRIBUTIONmost difficult intubation.

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© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-3 Learning, Endotracheal LLC Intubation NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The following steps are recommended in order yyClass IV indicates most difficult airway to to perform successful and safe endotracheal intubate. intubations. Other risk factors present for airway distor- Assess the airway – tion, any obstruction? 1. © JonesHAND & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC istory of difficult intubation? yyNeck mobility. yyH NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION yyAnatomic considerations present? yyDifficult airway should be considered if concerns 3-3-2 rule assessment. A difficult to intubate with any of the factors above. airway may be present if one of or more of 2. Preoxygenate using 100% oxygen, bag-valve mask the following are present: with PEEP valve. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC yy 3. Prepare. NOT FORPatient’s SALE mouth OR cannotDISTRIBUTION be opened to per- NOT FOR SALE OR DISTRIBUTION mit placement of three fingers between yyPatient: Sniffing position, headboard off and pa- the upper and lower teeth. tient head just below intubator’s xyphoid process yyThree fingers do not fit under the chin be- yyMedications: Free-flowing IV, premedication, tween the tip of the jaw and the beginning induction, paralytic and vasopressor agents © Jones & Bartlett Learning,of the neck. LLC © JonesyyRight & Bartlett side: Suction, Learning, endotracheal LLC tube with NOT FOR SALE ORyy DISTRIBUTIONThere is not enough space for two fingersNOT FORstylet SALE and syringe OR DISTRIBUTION attached between the thyroid notch and the floor of yyLeft side: Laryngoscope handle, blades, oral and the mandible. nasal airways end-tidal CO₂ detector Modified Mallampati classification is employed 4. Review team member roles, primary and backup to assess probable© Jones difficulty & Bartlett of intubation. Learning, LLCintubation plans. © Jones & Bartlett Learning, LLC yyOropharyngealNOT FOR examination SALE ofOR the DISTRIBUTION tongue, 5. Oxygen cut offs: Identify signalsNOT toFOR abort; SALE reinitiate OR DISTRIBUTION hard palate, soft palate, uvula, and poste- bag-valve mask ventilation. rior pharynx during laryngoscopy. 6. Administer medication, if indicated. yyClassification (I through IV) is based on 7. Confirm endotracheal tube placement using two © Jonesstructures & Bartlett visible Learning, during the oralLLC pharyn- indicators© (including Jones end-tidal& Bartlett CO₂). Learning, LLC geal exam. NOT FOR SALE OR DISTRIBUTION 8. Hold endotrachealNOT FOR tube SALE until secured. OR DISTRIBUTION yyClass I indicates least difficult airway to Data from the American College of Chest Physicians Airway intubate. Management Program Curriculum, 2013.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC early complications. Because of this, well over half (66% stabilization on the ventilator when it becomes appar- NOT FOR SALEto 86%) ofOR tracheostomies DISTRIBUTION performed are now percutaneNOT- ent FOR that SALEthe patient OR will DISTRIBUTION require prolonged ventilatory ous tracheostomies.12,13 Advantages of tracheostomy (as assistance. Early tracheostomy may be beneficial in pa- compared to endotracheal intubation) include improved tients who require high levels of sedation to tolerate the patient comfort, less sedation/analgesia required, re- endotracheal tube. As noted, tracheostomy placement 14 duced oral/laryngeal ©injury, Jones and improved & Bartlett oral care.Learning, LLCmay slightly reduce airway resistance© Jones and & anatomic Bartlett Learning, LLC Tracheostomy can also improve patient communication dead space and reduce WOB. Patients may derive bene- by enabling lip-readingNOT or the FOR use of SALE speaking OR valves. DISTRIBUTION fit from the ability to eat orally,NOT communicate FOR SALE by articu- OR DISTRIBUTION Tracheostomy better preserves the swallow, allowing for lated speech, and enhanced mobility. earlier feeding and helps maintain glottic competence, Tracheostomy is not without complications, which which may have some benefit in avoiding aspiration and may include infection of the wound site, pneumothorax, the development of ventilator-associated pneumonia.14 subcutaneous emphysema, tube obstruction, and ac- © Jones & Bartlett Learning, LLC © Jones &16–18 Bartlett Learning, LLC NOTTracheostomy FOR SALE may also OR slightly DISTRIBUTION reduce anatomic cidental decannulation.NOT FOR SALE Later ORcomplications DISTRIBUTION include dead space (due to bypass of the upper airway), de- aspiration (30% to 50% of patients), pneumonia, tra- crease airway resistance and WOB, improve secretion cheal stenosis, tracheoarterial fistula (most commonly clearance, reduce the need for sedation, and decrease tracheoinnominate artery fistula), tracheoesophageal the risk of aspiration.15,16 Because of these advantages, fistula, and tracheomalacia.12,14,16,19,20 Tracheostomy some have speculated that tracheostomy may facilitate bypasses the natural warming, filtration, and humidi- © Jones & Bartlett Learning, LLC 15,17,18 © Jones & Bartlett Learning, LLC NOT FOR SALEventilator OR weaning DISTRIBUTION in certain patients. Trache- NOTfication FOR SALE provided OR by theDISTRIBUTION upper airway. Inadequate hu- ostomy should be considered after an initial period of midification can lead to chronic inflammatory changes,

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© Jones &squamous Bartlett metaplasia, Learning, desiccation LLC of the tracheal mu- © Jonesthen advanced & Bartlett distal Learning, to the tracheostomy LLC stoma and the cosa, and reduced ciliary function. Tracheostomy also cuff inflated.16 As a last resort, the artery may be digitally NOT FOR SALE OR DISTRIBUTION 16 NOT FOR SALEdiminishes OR cough DISTRIBUTION effectiveness and may hamper an ef- compressed using a finger placed through the stoma. fective swallow. In summary, the effect of early tracheostomy on hos- Although rare (especially with the higher position of pital mortality, duration of mechanical ventilation, and tracheostomy tubes done percutaneously), innominate development of ventilator-associated pneumonia re- 21,22 artery erosion (i.e., tracheoarterial© Jones & fistula)Bartlett can Learning,lead to LLCmains unclear. Tracheostomy© Jones appears & to Bartlett have bene- Learning, LLC massive hemorrhageNOT and death. FOR Immediate SALE OR recognition DISTRIBUTION fits in terms of reduced sedationNOT requirements, FOR SALE patient OR DISTRIBUTION and maneuvers to sustain the patient until surgical re- comfort, resumption of oral feeding, decreased oral and pair can be done should be applied.16 For example, the laryngeal injury, and reduced WOB. Early tracheostomy tube cuff may be overinflated to compress the innomi- should be considered in patients likely to require pro- nate artery, or an endotracheal tube inserted allowing longed mechanical ventilation. Box 6-4 lists the indica- for ©removal Jones of the& Bartletttracheostomy Learning, tube. The LLCETT tip is tions, contraindications,© Jones & and Bartlett hazards Learning,of tracheostomy. LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION BOX 6-4 Indications, Contraindications, and Complications of Tracheostomy Indications Complications During the Procedure Provide secure airway for mechanical Bleeding © Jones & Bartlettventilation Learning, (especially LLC prolonged mechanical © JonesAirway & Bartlett obstruction/malfunction Learning, LLC NOT FOR SALEventilation). OR DISTRIBUTION NOT FORHypoxemia/hypoventilation SALE OR DISTRIBUTION Failure to wean from the ventilator in 1 to 3 weeks following endotracheal intubation. Complications Following the Procedure Airway malfunction Advantages yyObstruction Improve weaning© parametersJones & (e.g.,Bartlett rapid shallowLearning, LLC © Jones & Bartlett Learning, LLC yySecretions breathing indexNOT [RSBI]). FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION yyCuff leaks Reduce WOB. yyPilot balloon failure Improve patient comfort. yyAspiration of secretions due to cuff failure or Reduce need for sedation and analgesia. improper inflation © ImprovedJones &patient Bartlett mobility. Learning, LLC © Jones & Bartlett Learning, LLC yyAccidental decannulation NOTImproved FOR patient SALE communication OR DISTRIBUTION (speaking tubes, NOT FOR SALE OR DISTRIBUTION yyMigration of the tube lip-reading). Pneumothorax; subcutaneous emphysema Allow patient to eat orally. Postoperative hemorrhage Improved secretion clearance and ease of © Jones & Bartlettsuctioning. Learning, LLC © JonesInfection & Bartlett Learning, LLC NOT FOR SALEEasier OR nursing DISTRIBUTION care. NOT FORNosocomial SALE pneumonia OR DISTRIBUTION Percutaneous tracheostomy is faster, less expen- Reduced or lost phonation (vocal fold sound pro- sive, and may be performed at the bedside. duction, speech) Tracheoarterial fistula (e.g., tracheal innominate Contraindications artery erosion) Age < 15 years (percutaneous© Jones & tracheostomy)Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Wound infection Bleeding diathesisNOT (tendency FOR SALEto bleed, OR e.g., DISTRIBUTIONclotting NOT FOR SALE OR DISTRIBUTION Oral secretion aspiration (cuff failure or poor cuff disorder) maintenance) Neck tumor Complications at the cuff site Thyromegaly (enlarged thyroid) © Jones & Bartlett Learning, LLC yyTracheomalacia© Jones & Bartlett Learning, LLC Tracheomalacia (weak, soft, floppy tracheal yyTracheoesophageal fistula (more common with NOTcartilages) FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION endotracheal intubation) Soft-tissue infection yyTracheal stenosis Obesity Complications associated with suctioning (e.g., Cervical spine instability © Jones & Bartlett Learning, LLC © Joneshypoxemia, & Bartlett arrhythmias, Learning, vagal stimulation,LLC brady- Short neck NOT FOR SALE OR DISTRIBUTION NOT FORcardia, SALE hypotension, OR DISTRIBUTION and cardiac arrest)

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© Jones &Choice Bartlett Learning,of a Ventilator LLC © JonesCurrent & Bartlett adult critical Learning, care ventilators LLC in common use include the Covidien Puritan Bennett series (PB 840, PB Prior to initiation of mechanical ventilation, the respira-NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 980), Dräger Evita series (Evita XL, Evita Infinity V500), tory care clinician must choose an appropriate ventila- GE Healthcare CARESCAPE R860, Getinge Group tor. Ventilator choice should be driven by consideration Maquet Servo ventilators (Servo-s, Servo-i,, Servo-u), of the patient’s needs, the goals to be achieved, patient Hamilton Medical Ventilators (Hamilton G-5, safety, and the clinician’s familiarity with the ventilator Hamilton C-3), and Vyaire ventilators (AVEA, to be employed. For ©example, Jones an & unstable, Bartlett critically Learning, ill LLC © Jones & Bartlett Learning, LLC VELA). Other ventilators for use in acute and postacute patient in acute ventilatoryNOT FORfailure SALEwith severe, OR refrac-DISTRIBUTION NOT FOR SALE OR DISTRIBUTION care include the Covidien Newport e360 ventilator and tory hypoxemia may require a ventilator with in-depth the Vyaire LTV 1200 and LTV 1150. Ventilators especially monitoring and graphics capabilities able to apply so- well-suited to provide NIV include the Philips Respiron- phisticated modes of ventilation. On the other hand, a ics ventilators (e.g., V60, V200, BiPAP, and Trilogy series) long-term high cervical spinal cord injury patient with and Devilbiss ventilators (e.g., Intelli PAP AutoBilevel and little© or Jones no lung & injury Bartlett may require Learning, a dependable LLC and © Jones & Bartlett Learning, LLC Bilevel S). High-frequency ventilators include the Vyaire reliableNOT ventilator FOR SALE able to ORsafely DISTRIBUTION support the patient; so- NOT FOR SALE OR DISTRIBUTION 3100B Oscillator, Percussionaire VDR-4, and Bunnell Life phisticated graphics packages and modes of ventilation Pulse high-frequency ventilator. There are also transport may not be needed. Patients expected to continue to and home care ventilators available, although these ven- make spontaneous ventilatory efforts during ventilatory tilators in general are not appropriate for continuing sup- support may do well with a ventilator able to provide port of patients in the ICU. To summarize, factors that © Jones & aBartlett mode of ventilation Learning, that LLC better promotes patient– © Jones & Bartlett Learning, LLC should be considered when choosing a ventilator include: NOT FOR SALEventilator OR synchrony. DISTRIBUTION An apneic patient generally will NOT FOR SALE OR DISTRIBUTION require time-triggered volume ventilation (aka control ■■ Clinical goals and patient’s needs mode), while a COPD patient with acute respiratory ■■ Availability failure may do well with NIV. ■■ Reliability When choosing a specific ventilator, features, modes ■■ Ventilator features available, pressure and© flowJones capabilities, & Bartlett and integrated Learning, LLC■■ Alarms and monitoring© capabilities Jones & Bartlett Learning, LLC alarms and monitoringNOT systems FOR should SALE be considered.OR DISTRIBUTION ■■ Modes available NOT FOR SALE OR DISTRIBUTION Reliability, cost, and familiarity with the ventilator ■■ Cost are also important factors in ventilator choice. Most ■■ Clinician’s familiarity with the ventilator modern ventilators have sufficient pressure and flow Chapter 4 provides additional information regarding capabilities to ventilate patients with low compliance, specific critical care ventilators currently available. high© resistance,Jones & or Bartlett markedly Learning,increased inspiratory LLC flow © Jones & Bartlett Learning, LLC demands.NOT FORThe ventilator SALE ORchosen DISTRIBUTION should adequately and NOT FOR SALE OR DISTRIBUTION safely ventilate patients under changing conditions and RC Insight provide the features and modes required. Most ventilator manufacturers offer several ventilators with differ- The most important factor in choice of ventilator ent capabilities and features. Typically, manufacturers is the clinician’s familiarity with the device. © Jones & willBartlett offer a Learning,sophisticated, LLC high-end ventilator for criti- © Jones & Bartlett Learning, LLC NOT FOR SALEcal care ORuse that DISTRIBUTION incorporates a number of modes and NOT FOR SALE OR DISTRIBUTION special features. The same manufacturer may also offer an intermediate critical care ventilator that does not Choice of Mode include some modes of ventilation and/or some specific The mode of ventilation is determined by the control features. These intermediate ventilators are often less variable (e.g., volume control [VC] or pressure control expensive and may be© easier Jones to operate & Bartlett by personnel Learning, LLC[PC]), breath sequence (e.g., continuous© Jones mandatory& Bartlett Learning, LLC unfamiliar with newerNOT and moreFOR sophisticated SALE OR modes DISTRIBUTION ventilation [CMV] or intermittentNOT mandatory FOR SALE venti- OR DISTRIBUTION of ventilation. Manufacturers also often offer specific lation [IMV]), and targeting scheme employed.4,5 ventilators for patient transport or very short-term use. Mandatory breaths occur when the start and/or end of While most of the newer critical care ventilators have inspiration is determined by the ventilator, independent NIV capability, some manufacturers offer ventilators of the patient. A mandatory breath may be patient or that© are Jones designed & Bartlettprimarily for Learning, NIV. In a similar LLC fashion, time triggered© Jones to inspiration & Bartlett but is cycled Learning, to expiration LLC someNOT ventilators FOR SALE are designed OR DISTRIBUTIONprimarily for use in the by ventilator-determinedNOT FOR SALE parameters, OR whichDISTRIBUTION may be set neonatal intensive care unit, while other ventilators are by the clinician or automatically determined by the ven- able to support infants, children, and adults. Several tilator. For example, continuous mandatory manufacturers offer ventilators particularly suited for ventilation (CMV) may incorporate mandatory breaths long-term or home-care use. As manufacturers de- that are time or patient triggered to inspiration © Jones & velopBartlett and market Learning, newer ventilators,LLC older models are © Jones(assist-control) & Bartlett and volumeLearning, or time LLC cycled to expiration. NOT FOR SALEoften gradually OR DISTRIBUTION phased out, and may be acquired at a NOTIMV FOR intersperses SALE OR mandatory DISTRIBUTION breaths with spontaneous reduced cost. breaths. By definition, spontaneous breaths are initiated

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© Jones &by Bartlett the patient Learning, and the patient LLC determines when the end© Jonesdifferent & Bartlettterms to refer Learning, to the same LLC mode. As noted, of inspiration occurs. In order to allow for spontane- NOTwhat FOR distinguishes SALE OR different DISTRIBUTION modes of ventilation are NOT FOR SALEous breathing OR DISTRIBUTION through the ventilator circuit, modern the control variables (pressure or volume), breath ventilators incorporate a patient trigger to provide in- sequence (CMV, IMV, or CSV), and the targeting spiratory gas flow and a cycle mechanism to allow flow scheme or schemes used for the primary and secondary to be patient cycled to expiration. Spontaneous breaths breaths.4,5 The primary breath generally refers to man- provided by the ventilator© Jones may include & Bartlett pressure Learning, sup- LLCdatory breaths (CMV or IMV)© althoughJones with& Bartlett continu- Learning, LLC port or automatic tubeNOT compensation FOR SALE during OR inspiration DISTRIBUTION ous spontaneous breathing (absentNOT mandatoryFOR SALE breaths) OR DISTRIBUTION and may include CPAP during inspiration and expira- spontaneous breaths would be considered primary. The tion. The only requirement for a breath to be classified secondary breaths are those that occur in addition to as spontaneous is that the breath is patient triggered to the primary breaths. For example, IMV combines man- inspiration and patient cycled to expiration. Recall that datory breaths with spontaneous breaths. To further PSV© is Jones patient triggered& Bartlett to inspiration Learning, and cycledLLC to ex- complicate the© Jones nomenclature, & Bartlett there are Learning, seven basic LLC pirationNOT when FOR the SALE patient’s OR inspiratory DISTRIBUTION flow rate declines targeting schemesNOT FOR(set point SALE [s], dual OR [d], DISTRIBUTION biovariable to a preset value; thus, PSV can be considered a form of [b], servo [r], adaptive [a], optimal [o], and intelligent spontaneous ventilation.4,5 [i]).4,5 For example, for the Covidien PB 840 and PB 980, To review, the common control variables are PC or in the assist-control (A/C) volume-control mode the VC for the primary breath. Theprimary breath is de- clinician sets the tidal volume, peak flow, and trigger © Jones & finedBartlett as either Learning, the spontaneous LLC breath in continuous © Jonessensitivity. & Bartlett The tidal Learning, volume and LLCflow waveform are set NOT FOR SALEspontaneous OR DISTRIBUTIONventilation (CSV), the mandatory breath inNOT by FOR the clinician SALE andOR not DISTRIBUTION adjusted automatically by the continuous mandatory ventilation (CMV), or the man- ventilator. This is referred to as set-point targeting; the datory breath in intermittent mandatory ventilation. recommended nomenclature for this mode would be With CSV, all breaths are spontaneous. With CMV, all VC-CMVs where the s indicates the set-point target- breaths are mandatory. With IMV, spontaneous breaths ing scheme.4,5 Other names used for VC-CMVs include are interspersed with© mandatory Jones & breaths. Bartlett Using Learning, the LLCCMV and VC-CMV (Dräger Evita© Jones XL and & Evita Bartlett Infin- Learning, LLC breath sequence of eitherNOT CSV, FOR CMV, SALE or IMV OR coupled DISTRIBUTION ity V500 respectively [VC-CMVNOT provided FOR bySALE the V500 OR DISTRIBUTION with the control variable of either pressure or volume, is time triggered only]), and synchronized controlled the clinician can describe the basic mode of ventilation mandatory ventilation (Hamilton G5, Hamilton being employed. Using this system, the five basic C-3). The Maquet Servo-i and Servo-u have a similar modes of ventilation available are: VC-CMV, VC-IMV, mode called volume control; this mode allows patient or 5 PC-CMV,© Jones PC-IMV, & Bartlett and PC-CSV. Learning, LLC time triggering© Jones (i.e., assist-control). & Bartlett Learning, LLC NOTWithin FOR these broadSALE modes, OR DISTRIBUTIONthere are several For the CovidienNOT FOR PB 840 SALE and PB OR 980 DISTRIBUTION in the SIMV vol- variations that can be distinguished by their targeting ume control with pressure support mode, the clinician schemes. There are seven targeting schemes in current sets the tidal volume, peak flow, and trigger sensitivity use: set-point (s), dual (d), servo (r), adaptive (a), bio- for the mandatory breaths and the pressure-support variable (b), optimal (o), and intelligent (i).5 The mode level for spontaneous breaths. The recommended no- © Jones & ofBartlett ventilation Learning, can be further LLC described by placing the © Jonesmenclature & Bartlett for this modeLearning, of ventilation LLC would be VC- targeting scheme subscripts after the basic mode de- IMV , indicating a set-point targeting scheme for both NOT FOR SALE OR DISTRIBUTION NOT FORs,s SALE OR DISTRIBUTION scription. For example, assist-control volume ventilation primary and secondary breaths. VC-IMVs,s is simply (aka volume control-continuous mandatory ventilation) called SIMV by Dräger and Hamilton (Dräger Evita with set-point breath targeting can be further described XL, Dräger Evita Infinity V500, and Hamilton Medi- as VC-CMVs. Volume control-SIMV with set-point cal G5 and C-3). Dual targeting allows the ventilator breath targeting for both mandatory and spontaneous to automatically switch between volume control and © Jones & Bartlett Learning, LLC © Jones4,5 & Bartlett Learning, LLC breaths would be described as VC-IMVs,s. These target- pressure control during a single breath. The Maquet ing schemes are furtherNOT described FOR SALEin Table OR6-2. DISTRIBUTIONServo-i and Servo-u incorporateNOT dual FOR targeting SALE when OR DISTRIBUTION Currently, there are very large number of modes of using AutoMode for PC, VC, and PRVC. In this case, ventilation available. While many of these modes have dual targeting allows the ventilator to automatically distinct advantages from a theoretical point of view, switch between volume or pressure control and pres- research© Jones demonstrating & Bartlett that Learning,a specific mode LLC is more ef- sure support© during Jones a single & Bartlett breath. Learning, LLC fectiveNOT in FORimproving SALE patient OR outcomes DISTRIBUTION is often lacking. NOT FOR SALE OR DISTRIBUTION Consequently, we will focus on common modes used to Full and Partial Ventilatory Support provide adult ventilatory support. Other, newer modes Mechanical ventilation may be employed to provide will be discussed later in this section. 100% of the WOB required to meet the patient’s ventila- More on Nomenclature tory needs. In such cases, the patient is receiving full © Jones & Bartlett Learning, LLC © Jonesventilatory & Bartlett support. Learning,Other modes LLCof ventilation may be NOT FOR SALENomenclature OR DISTRIBUTION for different modes of ventilation can NOTselected FOR SALE that do notOR provide DISTRIBUTION 100% of the patient’s ven- be confusing and specific manufacturers often use tilatory needs and require the patient to provide some

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© Jones & BartlettTABLE 6-2 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEVentilator OR Modes DISTRIBUTION and Targeting Schemes NOT FOR SALE OR DISTRIBUTION The five basic ventilator modes are:

Mode Abbreviation Common Terminology Volume control-continuous© mandatoryJones ventilation& Bartlett Learning,VC-CMV LLC Assist-control ©volume Jones ventilation & Bartlett Learning, LLC Volume control-intermittentNOT mandatory FOR ventilation SALE OR DISTRIBUTIONVC-IMV IMV or SIMV volumeNOT ventilation FOR SALE OR DISTRIBUTION

Pressure control-continuous mandatory ventilation PC-CMV Pressure-control ventilation (PCV)

Pressure control-intermittent mandatory ventilation PC-IMV IMV pressure-control ventilation

Pressure© Jones control-continuous & Bartlett spontaneous Learning, ventilation LLC PC-CSV © JonesThe most & commonBartlett form Learning,is PSV LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The seven available targeting schemes* are:

Name Abbr. Description Example

Set-point s The clinician sets the volume and flow waveforms for VC and Covidien PB 840 and PB 980: A/C volume © Jones & Bartlett Learning, LLCthe pressure and pressure waveform© Jones for PC. Set-point & Bartlett breath Learning,control (VC-CMVs). LLC targeting is easy to understand and apply. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Dual d The ventilator can automatically switch between VC and PC Evita XL, Evita Infinity V500:CMV with during a single inspiration. Originally introduced as volume- pressure-limited ventilation (VC-CMVd). assured pressure support (VAPS) in which a breath began as a pressure-support breath and then could switch to a volume- control breath if tidal volume target was not being achieved. © JonesDual & Bartletttargeting may Learning, also be used to LLCswitch between © Jones & Bartlett Learning, LLC NOT FORvolume-control SALE and OR pressure-support DISTRIBUTION breaths. With flow NOT FOR SALE OR DISTRIBUTION adaptive volume control, if the patient makes minimal or no effort, breath delivery is like assist-control VC-CMV. If the patient makes sufficient inspiratory effort, the breath changes to pressure support. Dual targeting can allow for consistent tidal volume © Jones & Bartlett deliveryLearning, but can beLLC complicated and difficult to set. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Servo r Proportional assist ventilation (PAV), automatic tube compen- Proportional assist ventilation is available sation (ATC), and neurally adjusted ventilatory assist (NAVA) on the Covidien PB 840 and PB 980 as are modes that incorporate servo targeting. proportional assist ventilation plus (PAV+). With servo targeting, ventilator output automatically PAV+ would be classified as PC-CSVr. adjusts based on varying input measures. For example, inspi- ATC is available on the Hamilton G5, Covi- © Jones & Bartlett Learning, LLCratory pressure may be adjusted© proportional Jones to & inspiratory Bartlett Learning,dien PB 840 and LLCPB 980, Dräger Evita XL effort; as effort increases support increases (and vice versa). and Infinity 500, Yvaire AVEA, Hamilton NOT FOR SALE OR DISTRIBUTION NOT FOR SALE ORG5, DISTRIBUTION and Maquet Servo-i and Servo-u. NAVA is available with the Maquet Servo-i and Servo-u.

Adaptive a The ventilator automatically adjusts targets between breaths Servo-i and Servo-u: Pressure-regulated in response to varying patient input. Adaptive targeting is volume control (PRVC or PC-CMVa). © Jonesused &in combinationBartlett with Learning, pressure control LLC to allow the ven- © Jones & Bartlett Learning, LLC NOT FORtilator toSALE automatically OR changeDISTRIBUTION the pressure-control level as NOT FOR SALE OR DISTRIBUTION needed to maintain a clinician-set target tidal volume. Adap- tive targeting can maintain a stable tidal volume in the face of changing pulmonary mechanics or patient inspiratory effort.

Biovariable b The ventilator randomly adjusts inspiratory pressure or tidal Evita Infinity V 500:Variable pressure sup- © Jones & Bartlett Learning,volume to simulate LLC the variability associated with normal© Jonesport & (PC-CSVb). Bartlett Learning, LLC NOT FOR SALE ORspontaneous DISTRIBUTION breathing. NOT FOR SALE OR DISTRIBUTION Optimal o Ventilatory pattern is automatically adjusted to optimize WOB Hamilton G5: Adaptive support ventila- in the face of changing lung mechanics or patient effort. tion (ASV or PC-IMVoi,oi).

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Intelligent i Artificial intelligence is used to adjust the ventilator in the Evita XL and Evita Infinity V 500: face of changing lung mechanics or patient inspiratory effort. Smart Care/PS (PC-CSVi) Intelligent breath targeting can adapt the ventilator in the face of patient changes similar to human decision making. © JonesIntelligent & Bartlett targeting may Learning, make inappropriate LLC ventilator © Jones & Bartlett Learning, LLC NOT FORchanges SALE if algorithm OR assumptions DISTRIBUTION are violated or do not NOT FOR SALE OR DISTRIBUTION match the patient’s actual physiology.

The mode of ventilation is determined by the control variable (e.g., VC or PC), breath sequence (e.g., CMV or IMV), and targeting scheme employed. * Note: the targeting scheme is indicated by the abbreviation following the major mode description. For example, volume-controlled continu-

ous mechanical ventilation with set-point targeting would be described as VC-CMVs. Targeting schemes for mandatory and spontaneous breaths© Jones are listed & for Bartlett IMV modes. ForLearning, example, SIMV LLC volume control with pressure support© (PB840Jones and & 980) Bartlett using set-point Learning, targeting for LLC spontaneousNOT FOR and mandatory SALE breathsOR DISTRIBUTION would be described as VC-IMVs,s, indicating set-pointNOT targeting FOR for bothSALE spontaneous OR DISTRIBUTION and mandatory breaths. Targeting schemes can be mixed in the IMV mode. For example, adaptive pressure ventilation SIMV (Hamilton G5) would be

described as PC-IMVa,s, indicating adaptive targeting for pressure-control breaths and set-point targeting for spontaneous breaths.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEportion ORof the DISTRIBUTION WOB in order to achieve effective venti-NOTsupport FOR SALEmay allow OR for DISTRIBUTION ventilatory muscle rest and re- lation. When less than 100% of the WOB is performed covery in cases of diaphragmatic fatigue. by the ventilator, this is known as partial ventilatory Controlled ventilation is a time-triggered form of support. Advantages and disadvantages of these two full ventilatory support that requires apnea. Controlled approaches are discussed below. ventilation eliminates the WOB and allows for complete control over the patient’s ventilatory pressures, volumes, Full Ventilatory Support© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONand flows. Controlled ventilationNOT will FOR reduce SALE oxygen OR DISTRIBUTION When mechanical ventilation is initiated to provide consumption of the ventilatory muscles and provide full ventilatory support, adequate alveolar ventilation ventilatory muscle rest. Administration of sedatives and is maintained even if the patient makes no spontane- (in some cases) neuromuscular-blocking agents (aka ous breathing efforts. Full ventilatory support can be paralytic drugs) may be needed to achieve controlled provided© Jones using & volume- Bartlett or pressure-controlled Learning, LLC ventila- ventilation. ©Neuromuscular-blocking Jones & Bartlett Learning,agents paralyze LLC tion.NOT The FORkey to SALEproviding OR full DISTRIBUTIONventilatory support is the voluntaryNOT muscles, FOR including SALE theOR diaphragm. DISTRIBUTION In the ventilator settings that deliver a tidal volume, respira- event of a ventilator malfunction or disconnect, the tory rate, and resultant minute ventilation sufficient patient will be unable to breathe spontaneously, and to provide 100% of the patient’s needs with little or no a catastrophic outcome may follow. It should also be work on the part of the patient. In the case of spontane- noted that paralytic agents do not alter cognitive func- 23 © Jones & ouslyBartlett breathing Learning, patients in LLC the CMV mode, the patient © Jonestion, perception, & Bartlett or theLearning, experience LLC of pain. Because of can trigger the ventilator (aka assist breaths); care this, neuromuscular-blocking agents should be given in NOT FOR SALEmust be OR taken DISTRIBUTION to minimize trigger work and maximize NOTconjunction FOR SALE with OR sedatives DISTRIBUTION and appropriate analgesics patient–ventilator synchrony. In the event of apnea, the for pain and anxiety. Neuromuscular-blocking agents set ventilator rate, tidal volume, and minute ventilation can also cause anaphylaxis, hypotension, cardiac ar- are sufficient, and the patient’s WOB is zero. The term rhythmias, electrolyte disturbances, and prolonged controlled ventilation 23 © is Jonessometimes & usedBartlett to refer Learning, to LLCparalysis and muscle weakness.© Jones Neuromuscular- & Bartlett Learning, LLC time-triggered continuous mandatory ventilation and blocking agents used in the ICU include vercuronium should not be confusedNOT with FOR volume SALE control OR or pressureDISTRIBUTION (Norcuron), pancuronium (Pavulon),NOT FOR and cisatracurium SALE OR DISTRIBUTION control. (Nimbex). Neuromuscular-blocking agents should be Full ventilatory support is required in the presence used cautiously, and other options should be considered of apnea. Causes of apnea include anesthesia, sedative for managing patient agitation, excessive movement, or 23 or ©narcotic Jones drugs, & Bartlett cardiac arrest, Learning, heart failure, LLC shock, ventilator asynchrony.© Jones & Prolonged Bartlett controlled Learning, ventilation LLC trauma, head injury, cerebral hypoxia, neurologic/ may also result in ventilatory muscle atrophy and reduc- neuromuscularNOT FOR diseaseSALE (e.g., OR major DISTRIBUTION stroke, spinal cord tions in diaphragmaticNOT FOR muscle SALE strength OR DISTRIBUTION and endurance.24 injury, and brain death), poisoning (e.g., carbon mon- To summarize, full ventilatory support provides oxide, cyanide) and administration of neuromuscular- 100% of the patient’s ventilatory needs. Full ventilatory blocking agents (e.g., succinylcholine, rocuronium). Full support can be provided using assist-control volume- © Jones & ventilatoryBartlett supportLearning, is also LLC generally indicated as an ini-© Jonescontrol & ventilation Bartlett (aka Learning, VC-CMV), LLC assist-control tial approach for patients with severe respiratory failure pressure-control ventilation (PC-CMV), and volume- or NOT FOR SALEand increased OR DISTRIBUTION WOB. Properly applied, full ventilatory NOTpressure-control FOR SALE OR SIMV DISTRIBUTION (e.g., VC-IMV or PC-SIMV).

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Partial Ventilatory Support volume control-intermittent mandatory ventilation © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC (VC-IMV), pressure control-intermittent mandatory NOT FOR SALEWhen mechanical OR DISTRIBUTION ventilation is initiated to provide NOT FOR SALE OR DISTRIBUTION partial ventilatory support, the ventilator settings and ventilation (PC-IMV), and pressure control-continuous mode require that the patient provide a portion of the spontaneous ventilation (PC-CSV). VC-CMV and ventilation and associated work required to maintain VC-IMV are the most frequently used forms of ventilation for adult patients at many institutions and most an acceptable Paco2. The most common form of par- 25,26 tial ventilatory support© Jonesis IMV with & Bartlett mandatory Learning, rates LLCclinicians are familiar with these© Jones two modes. & BartlettWhile Learning, LLC less than 8 to 10 breaths/min.NOT FOR This SALE requires OR the DISTRIBUTIONpatient multiple breath-targeting schemesNOT areFOR used SALE in various OR DISTRIBUTION to breathe spontaneously between mandatory breaths adaptations of these five basic modes, we will focus our at a spontaneous rate and tidal volume sufficient (in discussion to use of these modes where the clinician combination with the ventilator’s support) to maintain determines most ventilator parameters (i.e., set-point effective alveolar ventilation. With partial ventilatory breath targeting). Advantages and disadvantages of each support© Jones in the IMV& Bartlett mode, should Learning, the patient’s LLC spon- of these major© Jonesmodes are & discussedBartlett below. Learning, LLC taneousNOT breathing FOR SALE cease orOR become DISTRIBUTION inadequate, acute NOT FOR SALE OR DISTRIBUTION hypercapnia and respiratory acidosis may occur. Full Volume Control-Continuous Mandatory ventilatory support can be provided using IMV if the Ventilation (VC-CMV) mandatory rate, tidal volume, and resultant minute VC-CMV with set-point breath targeting is commonly ventilation meets all the patient’s needs (e.g., Vt ≥ 6 to © Jones & Bartlett Learning,≥ LLC © Jonesreferred & toBartlett as volume-limited Learning, ventilation, LLC volume- 8 mL/kg and f 10 to 12 breaths/min). targeted ventilation, volume-cycled ventilation, volume NOT FOR SALEThere OR are DISTRIBUTIONseveral other modes of ventilation that NOTassist-control FOR SALE (VA/C), OR DISTRIBUTION or just plain volume ventilation. require the patient to breathe spontaneously. These VC-CMV may be patient or time triggered to inspira- include PSV, volume support (VS), PAV, and NAVA, tion and is volume cycled to expiration. Typically, the all of which can be used to provide partial ventilatory clinician sets the desired tidal volume, minimum man- support. © Jones & Bartlett Learning, LLCdatory (machine) rate, inspiratory© Jones peak flow, & Bartlett and trigger Learning, LLC Mandatory minute ventilation (MMV) and adaptive sensitivity. Other ventilators instead have the clinician support ventilation (ASV)NOT automaticallyFOR SALE vary OR the DISTRIBUTION level set the desired tidal volume, mandatoryNOT FOR (machine) SALE rateOR DISTRIBUTION of mechanical ventilatory support with changes in the and inspiratory time, or inspiratory percentage time. patient’s spontaneous minute ventilation. Thus, MMV Most ventilators also allow the clinician to select the and ASV adjust automatically to provide partial or full inspiratory flow waveform, typically as a square wave or ventilatory support as the patient’s spontaneous minute © Jones & Bartlett Learning, LLC down ramp,© although Jones some & Bartlett ventilators Learning, have a sinewave LLC ventilation varies. option (e.g., Hamilton G5). A square flow waveform NOTIn summary, FOR partialSALE ventilatory OR DISTRIBUTION support requires the (aka constantNOT flow FOR waveform) SALE may OR reduce DISTRIBUTION mean air- patient to continue to breathe spontaneously to main- way pressure, which may be useful in patients who are tain adequate alveolar ventilation. Modes sometimes hemodynamically compromised.27 A down-ramp flow used to provide partial ventilatory support include waveform (aka decreasing flow waveform) may increase IMV/SIMV, PSV as a standalone mode, VS, PAV, and mean airway pressure, reduce peak inspiratory pressure, © Jones & NAVA.Bartlett Partial Learning, ventilatory LLC support may help maintain © Jonesand improve & Bartlett distribution Learning, of inspired LLC gases.27 NOT FOR SALEventilatory OR muscle DISTRIBUTION function and reduce the loss of ven-NOT FORWith SALE VC-CMV, OR every DISTRIBUTION breath is a mandatory breath tilatory muscle strength that sometimes occurs with 24,25 delivered at the clinician-selected Vt. Commonly mechanical ventilation. Partial ventilatory support referred to as assist-control volume ventilation, the may require less sedation and improve patient–ventilator patient can trigger the primary breath (aka assist synchrony in some patients. Because spontaneous breath). If no spontaneous effort is detected during breathing occurs during© Jones partial ventilatory & Bartlett support, Learning, LLCthe respiratory cycle time, the© ventilator Jones will& Bartlett provide a Learning, LLC there may be some advantagesNOT FOR in stabilizingSALE OR and DISTRIBUTION re- time-triggered breath (aka controlNOT breath). FOR SALEFigure 6-2 OR DISTRIBUTION cruiting alveoli because of the negative intrathoracic illustrates patient- and time-triggered VC-CMV. pressures that occur during spontaneous breathing. A Volume-control ventilation is available as A/C major disadvantage of partial ventilatory support is that volume control (Covidien PB 840 and PB P980), CMV it may not allow for adequate ventilatory muscle rest and VC-CMV (Dräger Evita XL and Evita Infinity V500) and© recovery Jones in & cases Bartlett where Learning,diaphragmatic LLC fatigue has and synchronized© Jones controlled & Bartlett mandatory Learning, ventilation LLC [(S) occurred.NOT FOR SALE OR DISTRIBUTION CMV] (HamilNOTton FOR G-5). SALE The ORMaquet DISTRIBUTION Servo-i and Major Modes of Ventilation Servo-u also feature a volume control mode, which (in the absence of Automode) functions as VC-CMV. As noted, there are five basic ventilatory modes at A major advantage of VC-CMV is the fact that it will the clinician’s disposal: volume control-continuous deliver a constant Vt in the face of changes in compli- © Jones & mandatoryBartlett Learning,ventilation (VC-CMV), LLC pressure control- © Jonesance and & Bartlettresistance limitedLearning, only by LLC the clinician-set NOT FOR SALEcontinuous OR mandatory DISTRIBUTION ventilation (PC-CMV), NOTmaximum FOR SALE pressure OR alarm DISTRIBUTION limit and the machine’s

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Flow (L/min) Flow –40 –60 © Jones & 2Bartlett46 Learning, LLC810121© Jones4 & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION O) 24 2 20 Patient-triggered Ventilator-triggered 16 breath breath 12 8 © Jones & Bartlett4 Learning, LLC © Jones & Bartlett Learning, LLC 0 essure (cm H Pr essure NOT FOR SALE OR DISTRIBUTION2 4681NOT01 FOR SALE21 OR4 DISTRIBUTION 600 500 400 300 © Jones & Bartlett Learning,200 LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTION (mL) Volume 100 NOT FOR SALE OR DISTRIBUTION 0 2 4 6810 12 14 Time (s)

FIGURE 6-2 Continuous ©Mandatory Jones Ventilation & Bartlett Illustrating Learning, Ventilator-Triggered LLC and Patient-Triggered Breaths. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION pressure and flow capabilities. A minimum guaranteed machine breath has been triggered. This can result in an minute ventilation (V˙e) will be delivered based on the increase in WOB, especially if inspiratory time or peak Vt and set backup rate. In the assist-control mode, the inspiratory flow rates are set improperly. patient© Jones can trigger & Bartlett the ventilator Learning, above the LLC set mini- Problems© with Jones patient–ventilator & Bartlett asynchronyLearning, may LLC mum respiratory rate; a minimum V˙e will be provided also occur due to inappropriate trigger-sensitivity set- in theNOT absence FOR of SALE a patient OR trigger DISTRIBUTION (e.g., apnea due to tings, high patientNOT FORtrigger SALE rates, or OR inadequate DISTRIBUTION peak sedation or CNS problems). Properly applied assist- inspiratory flow rates. For example, a patient in distress control volume ventilation provides full ventilatory sup- may trigger the ventilator at a rapid assist rate resulting port with a lower WOB then partial ventilatory support in decreased expiratory time and increased mean air- modes. Ventilatory muscle fatigue occurs due to high way pressures. Excessive patient effort required to trig- © Jones & ventilatoryBartlett workloads,Learning, such LLC as may occur in patients © Jonesger a mandatory & Bartlett breath Learning, will increase LLC the patient’s WOB. NOT FOR SALEwith acute OR respiratory DISTRIBUTION failure. Because VC-CMV can NOTThis FOR can SALE be caused OR by DISTRIBUTION inappropriate trigger sensitivity reduce or eliminate the WOB, it is especially well-suited or autoPEEP, both of which may increase trigger work. to allow for ventilatory muscle rest and recovery from Inappropriate peak inspiratory flow rate settings that ventilatory muscle dysfunction. It must be noted, how- do not meet or exceed the patient’s inspiratory flow ever, that prolonged ventilatory muscle inactivity may demand may increase the patient’s WOB and result in result in ventilatory muscle© Jones weakness & Bartlett and atrophy. Learning,24 LLCpatient–ventilator asynchrony.© InadequateJones & expiratory Bartlett Learning, LLC VC-CMV is easy to understandNOT FOR and SALE apply andOR is DISTRIBUTION well- times may cause the developmentNOT of FOR autoPEEP, SALE espe- OR DISTRIBUTION suited for most patients. cially in patients with obstructive lung disease. High Disadvantages of VC-CMV include the possible mean airway pressures may impede venous return and delivery of unsafe peak and plateau pressures (PIP and reduce cardiac output in hemodynamically comprom- Pplateau) in the presence of decreasing compliance or ised patients. Some patients who are awake, alert, and increasing© Jones airway & Bartlettresistance. Learning, Use of large tidal LLC volumes anxious do ©not Jones tolerate &VC-CMV Bartlett well, Learning, and other forms LLC mayNOT also resultFOR in SALE excessive OR PIP DISTRIBUTION and Pplateau and excessive of ventilatoryNOT support FOR may SALE be considered. OR DISTRIBUTION airway pressures may result in barotrauma or VILI. This Controlled ventilation (time-triggered VC-CMV) emphasizes the need for setting the ventilator alarms requires patient apnea, which in turn may require the at appropriate levels to alert the respiratory therapist administration of sedative and possibly paralytic agents, to make ventilator adjustments, when needed. It is also which can delay ventilator weaning and discontinuance. © Jones & importantBartlett toLearning, note that with LLC patient-triggered breaths, © JonesControlled & Bartlett ventilation Learning, may be required LLC in patients with NOT FOR SALEpatients OR continue DISTRIBUTION to actively inspire even though the NOTan FOR absent SALE ventilatory OR driveDISTRIBUTION due to CNS problems (e.g.,

9781284139860_CH06_311_366.indd 331 20/02/19 5:00 PM 332 CHAPTER 6 Ventilator Initiation

© Jones &coma), Bartlett spinal Learning, cord injury, LLCor neuromuscular paralysis. © JonesWith & PC-CMV,Bartlett the Learning, clinician sets LLC the pressure-control Provision of a relatively high minute ventilation via level, which assures (if properly set) that airway pres- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION time-triggered VC-CMV that meets all the patient’s sures remain in a safe range (Pplateau ≤ 28 to 30 cm physiologic needs may reduce the drive to breathe and H2O). PC-CMV provides a decreasing flow waveform cause an absence of patient-triggered breaths. Time- that varies flow with patient demand. For example, gas triggered VC-CMV eliminates diaphragmatic activity flow to the patient will increase with increased patient and the WOB. Patients© Jonesmay also &develop Bartlett ventilatory Learning, LLCeffort. This variable flow ©may Jones better match& Bartlett patient in- Learning, LLC muscle weakness, and atrophy and neuromuscular spiratory demand, improve patient comfort, provide NOT FOR SALE OR DISTRIBUTION24 NOT FOR SALE OR DISTRIBUTION weakness related to critical illness is not uncommon. better patient–ventilator synchrony and allow for earlier Diaphragmatic inactivity can cause atrophy in as little liberation from the ventilator. As noted, the square wave as 18 to 69 hours.28 Careful monitoring of the apneic inspiratory pressure waveform results in a decreasing patient is required as a ventilator malfunction or dis- flow waveform. The square wave inspiratory pressure connect© Jones can be &catastrophic Bartlett inLearning, patients unable LLC to spon- waveform also© Jonesresults in & more Bartlett sustained Learning, inspiratory LLC Box 6-5 taneouslyNOT FORbreathe. SALE OR summarizes DISTRIBUTION the advantages pressure, whichNOT may FOR improve SALE alveolar OR recruitment,DISTRIBUTION as and disadvantages of patient- and time-triggered VC- well as improve distribution of inspired gases. CMV (aka assist-control volume ventilation). Pressure rise time or slope may be adjusted by the clinician to adjust the rate at which inspiratory gas Pressure Control-Continuous Mandatory Ventilation flow increases from baseline to peak flow during the © Jones & PressureBartlett control-continuous Learning, LLC mandatory ventilation © Jonesfirst part& Bartlett of the inspiratory Learning, phase. LLC Rise time should be NOT FOR SALE(PC-CMV) OR with DISTRIBUTION set-point breath targeting is patient- NOTadjusted FOR SALE so that inspiratoryOR DISTRIBUTION gas flow meets or exceeds or time triggered to inspiration, pressure limited and patient demand. Slow rise times may not provide ad- time cycled to expiration. Other terms employed for equate flow and increase the WOB. Rapid rise times PC-CMV include pressure assist-control, pressure A/C, may provide more flow than necessary and result in an pressure-control ventilation (PCV), and (when used inspiratory pressure spike near the beginning of the in- © Jones & Bartlett Learning, LLCspiratory phase. © Jones & Bartlett Learning, LLC with an inverse I:E ratio) pressure-control inverse-ratio Δ = ventilation (PC-IRV).NOT With FORPC-CMV, SALE the respiratoryOR DISTRIBUTION Vt is determined by the pressureNOT FOR gradient SALE ( P OR DISTRIBUTION care clinician sets the respiratory rate, inspiratory time PIP – PEEP), inspiratory time, patient effort, and pul- (or inspiratory percent time), and inspiratory pressure monary mechanics (compliance and resistance). In increases as the inspiratory pressure limit. The clinician also determines the patient trigger general, Vt increases (assuming ventilatory mechanics, patient sensitivity and may adjust the inspiratory rise time or effort, inspiratory time, and PEEP are constant); de- ramp.© Jones During inspiration,& Bartlett airway Learning, pressure risesLLC to a pre- © Jones & Bartlett Learning, LLC creases in inspiratory pressure generally reduce Vt. setNOT value; FORinspiration SALE is terminated OR DISTRIBUTION when the inspiratory NOT FOR SALE OR DISTRIBUTION Changes in PEEP will affect delivered Vt if inspiratory time limit is reached. Normal adult inspiratory time (TI) is set at 0.6 to 1.0 seconds with a respiratory rate of 12 pressure is not simultaneously adjusted, although most to 20 breaths/min and I:E ratio of 1:2 or lower. Some ventilators in the pressure-control mode will automatically adjust inspiratory pressure with changes in PEEP patients do well with slightly longer TI (e.g., 0.8 to 1.2 Δ © Jones & seconds).Bartlett Typically, Learning, PC-CMV LLC results in a square wave-© Jonesto maintain & Bartlett a constant Learning, P. For initial LLC ventilator setup, inspiratory pressure generally is adjusted to achieve a NOT FOR SALElike inspiratory OR DISTRIBUTION pressure waveform and a decreasing NOT FOR SALE OR DISTRIBUTION or decelerating inspiratory flow waveform, which may Vt in the range of 6 to 8 mL/kg of ideal body weight

improve patient comfort and improve the distribution (IBW) while maintaining a safe plateau pressure (Pplateau ≤ 28 to 30 cm H O). of inspired gases. The square wave pressure pattern will 2 With PC-CMV, as inspiratory time (T ) increases, also increase mean airway pressure, which may improve I inspiratory flow to the patient decreases because of the oxygenation. Recall, ©however, Jones that & increased Bartlett mean Learning, air- LLC © Jones & Bartlett Learning, LLC decreasing flow waveform provided. If sufficient inspira- way pressure may impede venous return and reduce NOT FOR SALE OR DISTRIBUTIONtory time is provided, flow willNOT decrease FOR to SALE zero and OR any DISTRIBUTION cardiac output in patients with hemodynamic instabil- remaining inspiratory time will provide an inspiratory ity. Properly applied, PC-CMV provides full ventilatory hold or plateau. Increases in inspiratory time generally support and minimizes the WOB, which may be helpful will increase Vt up until the point at which flow reaches to rest the ventilatory muscles in the presence of venti- zero. latory© Jones muscle fatigue.& Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Initial ventilatorNOT FOR set up SALE for PC-CMV OR DISTRIBUTION includes selecting a TI that provides enough time for the inspiratory RC Insight flow to decrease to zero before beginning the expiratory phase. In cases where inspiratory flow does not reach With PC-CMV, tidal volume is adjusted by adjust- zero at end inspiration, increasing inspiratory time © Jones & Bartletting the pressure Learning, gradient LLC (ΔP = PIP–PEEP) to ob- © Joneswill tend & Bartlettto increase Learning, Vt. As noted, LLC if inspiratory time NOT FOR SALEtain the OR desired DISTRIBUTION Vt. NOTcontinues FOR SALE past the OR point DISTRIBUTION of zero gas flow, an inspiratory pause or hold will ensue, which may further improve the

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© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-5 Learning, Advantages LLC and Disadvantages of Volume Control-Continuous Mandatory NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Ventilation (VC-CMV) VC-CMV, commonly known as assist-control volume Disadvantages of VC-CMV ventilation, allows the clinician to set the desired tidal Unsafe peak inspiratory pressures (PIP > 35 to 40 volume (Vt), minimum mandatory (machine) rate (f), cm H O) may occur with reduced compliance or © Jones & Bartlett Learning, LLC 2 © Jones & Bartlett Learning, LLC inspiratory peak flow, and trigger sensitivity. Other increased airway resistance as the ventilator at- ventilators have theNOT clinician FOR set SALE tidal volume, OR DISTRIBUTION manda- tempts to maintain deliveredNOT Vt. FOR SALE OR DISTRIBUTION

tory (machine) rate, and inspiratory time or inspira- Unsafe plateau pressures (Pplateau > 28 to 30 cm tory percentage time and trigger sensitivity. VC-CMV H2O) may occur with inappropriate tidal volume allows for control of the Fio2 and the addition of PEEP. settings and/or reduced lung compliance, which Assist-control© Jones & volume Bartlett ventilation Learning, allows LLC for a patient may result© in Jones alveolar & overdistention. Bartlett Learning, LLC orNOT time FORtrigger, SALE whichever OR occurs DISTRIBUTION first. Controlled vol- Improper NOTtrigger FOR sensitivity SALE may OR increase DISTRIBUTION the WOB. ume ventilation is time triggered and requires apnea. Inspiratory flow rate is typically fixed and does Advantages of VC-CMV not vary with patient effort. This may cause Vt constant in the face of changes in compliance patient–ventilator asynchrony. © Jones & Bartlettand resistance Learning, (within LLC the clinician-set maximum © JonesInadequate & Bartlett ventilator Learning, flow rates LLC may increase the NOT FOR SALEpressure OR DISTRIBUTION limit and the machine’s pressure and flowNOT FORWOB SALEin spontaneously OR DISTRIBUTION breathing patients and re- capabilities). sult in patient–ventilator asynchrony. Guaranteed minimum minute ventilation delivered yyLow inspiratory flow rates also increase inspira- (V˙ e) based on set minimum f and Vt. tory time and (assuming a constant respiratory Provides full ventilatory support. © Jones & Bartlett Learning, LLCrate) decrease expiratory© time. Jones & Bartlett Learning, LLC Minimizes or eliminatesNOT FOR the WOB.SALE OR DISTRIBUTIONInadequate expiratory timesNOT may FORresult inSALE auto OR DISTRIBUTION yyPatient-triggered (assist) breaths should have PEEP, particularly in patients with obstructive lung minimal work if proper trigger sensitivity and disease. appropriate peak inspiratory flowrates are set in With patient-triggered breaths, patients continue spontaneously breathing patients. to actively inspire even though the ventilator has © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC yyTime-triggered ventilation (control mode) elimi- begun to provide support; this may increase the NOTnates FOR the SALE WOB but OR requires DISTRIBUTION apnea. WOB especiallyNOT FORin cases SALE of inappropriate OR DISTRIBUTION ventilator Allows for ventilatory muscle rest and recovery peak flow settings. from ventilatory muscle dysfunction. High mean airway pressures may reduce venous Flow waveform is adjustable on some ventilators. return and impede cardiac output in hemodynami- © Jones & BartlettyySquare Learning, wave flow LLC waveform (aka constant © Jonescally & unstable Bartlett patients. Learning, LLC NOT FOR SALE flowOR DISTRIBUTIONwaveform) may reduce mean airway pres-NOT FORHigh pressuresSALE OR may DISTRIBUTION result in barotrauma (e.g., sure and inspiratory time (in ventilators with pneumothorax, pneumomediastinum, pneumo- peak flow control) but increase peak inspira- peritoneum, and subcutaneous emphysema) or tory pressure (PIP). This flow waveform may be ventilator-induced lung injury (VILI). VILI is caused by useful in patients© Jones who are & hemodynamically Bartlett Learning, LLCalveolar overdistention (aka© volume Jones trauma), & Bartlett cyclic Learning, LLC alveolar expansion and collapse (aka atlectrauma), compromised.NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION yyDown ramp (aka decreasing flow waveform) or inflammation associated with mechanical venti- may increase mean airway pressure, reduce PIP, lation (aka biotrauma). and increase inspiratory time in ventilators with Patients may trigger the ventilator at a rapid rate the peak flow control. This may improve the dis- resulting in respiratory alkalosis, patient–ventilator © Jonestribution & ofBartlett inspired gasesLearning, and oxygenation. LLC asynchrony,© Jones and increased & Bartlett peak and Learning, mean airway LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Assist-control volume ventilation is easy to under- pressures. stand and apply and is a type of ventilation familiar Inappropriate inspiratory flow rates that do not to most clinicians. meet the patient’s inspiratory flow demand in spon- Mode is well-suited for most patients. taneously breathing patients may increase the WOB. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (Continues)

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© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-5 Learning, Advantages LLC and Disadvantages of Volume Control-Continuous Mandatory NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Ventilation (VC-CMV) (Continued) Assist-control volume ventilation may be poorly and anxiety. Prolonged use of paralytic agents is tolerated in patients who are awake, anxious, or uncommon in the modern ICU. in pain; this may© result Jones in the & patientBartlett fighting Learning, the LLCyyVentilator malfunction or© disconnectJones & can Bartlett be Learning, LLC ventilator. NOT FOR SALE OR DISTRIBUTIONcatastrophic in the presenceNOT of FOR apnea. SALE OR DISTRIBUTION Controlled ventilation (time-triggered VC-CMV) Development of ventilatory muscle weakness requires apnea. and atrophy is associated with controlled yySedative and (possibly) paralytic drugs may be ventilation, prolonged use of sedatives, and use of required. neuromuscular-blocking agents. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC yyParalytic drugs should not be administered alone NOTand FOR require SALE the addition OR DISTRIBUTION of sedatives for pain NOT FOR SALE OR DISTRIBUTION

distribution of inspired gases. That said, with patients use of sedatives and (sometimes) paralytic agents, as © Jones & makingBartlett spontaneous Learning, respiratory LLC efforts, excessive inspi-© Jonesspontaneously & Bartlett breathing Learning, patients generallyLLC do not toler- NOT FOR SALEratory times OR mayDISTRIBUTION cause patient–ventilator asynchrony. NOTate FOR the useSALE of inverse-ratio OR DISTRIBUTION ventilatory patterns well and Care should also be taken to ensure adequate expiratory may fight the ventilator. The clinician should also be time to avoid autoPEEP and gas trapping, especially in aware that increased mean airway pressures may reduce patients with obstructive lung disease. venous return and cardiac output in hemodynamically Disadvantages of PC-CMV include variable tidal vol- compromised patients. ume delivery in the face© Jones of changes & inBartlett the level ofLearning, patient LLCPC-CMV is available as A/C© pressureJones control & Bartlett Learning, LLC effort, system compliance,NOT FORor airway SALE resistance OR andDISTRIBUTION this (Covidien PB 840 and PB 980);NOT pressure-control FOR SALE OR DISTRIBUTION may result in inadvertent hypo- or hyperventilation. This ventilation plus assisted, CMV with Autoflow, and CMV requires the clinician to pay careful attention to delivered with Autoflow and tube compensation,(Dräger Evita ˙ Vt and VE and set the ventilator’s alarms appropriately. XL); pressure control assist-control, and volume control Changes in inspiratory time may also affect delivered assist-control with Autoflow (Evita Infinity V500);pressure Vt©. PC-CMV Jones may & Bartlett also result Learning,in a higher mean LLC airway control CMV,© pressure-control Jones & Bartlett CMV with Learning, tube-resistance LLC pressures,NOT FOR which SALEmay decrease OR DISTRIBUTIONvenous return and impair compensation,NOT adaptive FOR pressure SALE ventilation OR DISTRIBUTION CMV, cardiac output in hemodynamically unstable patients. and adaptive pressure ventilation and CMV with tube- As with other modes, improper trigger sensitivity may resistance compensation (Hamilton G-5). The Maquet increase WOB. Inadequate inspiratory flow rates, which Servo-i and Servo-u also feature pressure control and may occur with inappropriate rise time settings, may also pressure-regulated volume control modes. Box 6-6 sum- © Jones & increaseBartlett W OLearning,B and cause patient–ventilatorLLC asynchrony.© Jonesmarizes & the Bartlett advantages Learning, and disadvantages LLC of PC-CMV. As with other modes of ventilation, excessive airway NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION pressures may cause barotrauma or VILI and inadequate Volume-Controlled Intermittent expiratory times may result in the development of auto Mandatory Ventilation PEEP and air trapping. Some awake and alert patients will not tolerate PC-CMV. For example, pain and anxiety Volume-controlled intermittent mandatory ventilation may result in rapid patient-triggering© Jones & Bartlett rates, increased Learning, LLC(VC-IMV) intersperses volume-targeted© Jones mandatory& Bartlett Learning, LLC airway pressures, respiratory alkalosis, and patient– breaths with spontaneous breathing. VC-IMV is com- ventilator asynchrony.NOT Controlled FOR ventilationSALE OR (time- DISTRIBUTIONmonly referred to as volume-targetedNOT FOR SIMV SALE or V-SIMV. OR DISTRIBUTION triggered PC-CMV) requires apnea, which in turn may With SIMV mandatory breaths may be time or patient require the use of sedatives and possibly paralytic agents. triggered. Older forms of IMV did not allow for patient- Pressure-control inverse-ratio ventilation (PC-IRV) triggered mandatory breaths. With SIMV, if the patient is a© form Jones of PC-CMV & Bartlett in which Learning, the ventilator LLC is ad- does not trigger© Jones a breath & during Bartlett the time Learning, window LLC justedNOT so thatFOR inspiratory SALE OR time DISTRIBUTION is longer than expiratory provided, theNOT ventilator FOR will SALE provide OR a time-triggeredDISTRIBUTION time. PC-IRV increases mean airway pressure and may mandatory breath. SIMV was introduced to help avoid improve oxygenation in certain patients with severe breath stacking and reduce patient–ventilator asyn- hypoxemic respiratory failure despite optimal PEEP chrony, which can occur with time-triggered IMV. and appropriate Fio2. While PC-IRV can improve oxy- Most modern ventilators today provide SIMV. For © Jones & genation,Bartlett evidence Learning, of improvement LLC in other important © JonesVC-SIMV, & Bartlett the clinician Learning, sets Vt and LLC mandatory rate, in- outcomes (e.g., time on the ventilator, time in the ICU, spiratory peak flow or inspiratory time, trigger sensitiv- NOT FOR SALE OR DISTRIBUTION26 NOT FOR SALE OR DISTRIBUTION and mortality) is lacking. PC-IRV often requires the ity, and Fio2. Spontaneous breaths may include pressure

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© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-6 Learning, Advantages LLC and Disadvantages of Pressure Control-Continuous NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Mandatory Ventilation (PC-CMV) PC-CMV, commonly known as assist-control meet or exceed the patient’s inspiratory demand pressure-control ventilation (PCV), allows the clinician (i.e., appropriate rise time settings). to set the desired inspiratory pressure, minimum man- © Jones & Bartlett Learning, LLCyyTime-triggered ventilation© Jones(control mode)& Bartlett elimi- Learning, LLC datory (machine) rate (f), inspiratory time (or inspira- nates the WOB but requires apnea. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION tory percentage time), and trigger sensitivity. PC-CMV Allows for ventilatory muscle rest and recovery allows for control of the Fio2 and the addition of PEEP. from ventilatory muscle dysfunction if properly Assist-control PCV allows for a patient or time trigger, applied. whichever occurs first. Time–triggered control mode Decreasing flow waveform varies flow based on pa- PCV requires patient apnea. © Jones & Bartlett Learning, LLC tients’ inspiratory© Jones effort. & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Advantages of PC-CMV yyPatient comfort and patient–ventilator syn- Inspiratory pressure is constant in the face of chrony may improve with PC-CMV because inspi- changes in compliance and resistance. ratory flow varies with patient effort. yyPlateau pressure can be maintained at safe lev- yyDecreasing flow waveform (aka down ramp) in- © Jones & Bartlettels (PLearning,plateau ≤ 28 to LLC 30 cm H2O). © Jonescreases & Bartlett mean airway Learning, pressure LLC and may improve NOT FOR SALEyy ResultantOR DISTRIBUTION PIP may be lower than can be achievedNOT FORinspired SALE gas OR distribution DISTRIBUTION and oxygenation. with VC-CMV (square wave). yyDecreasing flow waveform results in a square yyRisk of alveolar overdistention is reduced with wave pressure pattern, which may open alveoli changes in compliance. earlier in the inspiratory phase, improve inspired yySquare wave-like© Jones inspiratory & Bartlett pressure waveformLearning, LLCgas distribution, and improve© Jones oxygenation. & Bartlett Learning, LLC results in moreNOT sustained FOR inspiratorySALE OR pressure, DISTRIBUTION yyImproved gas distributionNOT may FORallow forSALE use of OR a DISTRIBUTION which may improve alveolar recruitment. lower Vt. Desired Vt may be achieved by adjusting pressure yyPressure rise time or slope can be adjusted. Rise control level (PIP) or inspiratory time. time allows the clinician to adjust the rate at © yJonesyVt is determined & Bartlett by theLearning, pressure gradient LLC which ©inspiratory Jones gas& Bartlett flow increases Learning, from base- LLC (ΔP = PIP – PEEP), patient effort, inspiratory line to peak flow. Rise time should be adjusted NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION time (TI), and pulmonary mechanics (compliance to ensure that machine gas flow meets or ex- and resistance). ceeds patient demand. yyIncreasing ΔP by increasing PIP generally in- yyRise time adjustment of the pressure waveform creases Vt and vice versa. can be made to avoid a pressure spike at the © Jones & BartlettyyIn cases Learning, where inspiratory LLC flow does not reach © Jonesbeginning & Bartlett of inspiration Learning, due toLLC rapid rise times NOT FOR SALE zeroOR atDISTRIBUTION end inspiration, increasing inspiratory NOT FORin whichSALE the OR flow DISTRIBUTION to the patient exceeds patient time will tend to increase Vt. demand. yyPEEP changes may affectΔ P and delivered Vt. PEEP yyRise time should also be adjusted to ensure that alterations will require attention to alterations inspiratory gas flow is not too slow and meets in PIP to maintain© Jones the same & Δ BartlettP and tidal Learning,volume LLCor exceeds patient demand.© Jones Slow rise & times Bartlett may Learning, LLC delivery. NOT FOR SALE OR DISTRIBUTIONincrease WOB. NOT FOR SALE OR DISTRIBUTION yyIncreased patient inspiratory effort will generally Pressure-control inverse-ratio-ventilation (PC-IRV) increase Vt; decreased effort tends to decrease Vt. has been suggested for severe hypoxemic respira- Properly applied, PC-CMV can provide full ventilatory failure (e.g., severe ARDS) where optimal PEEP tory support. and Fio2 have been ineffective in providing ade- © Jones & Bartlett Learning, LLC quate oxygenation.© Jones While & Bartlett PC-IRV may Learning, improve oxy- LLC PC-CMV may minimize or eliminate the WOB. NOT FOR SALE OR DISTRIBUTION genation,NOT cardiac FOR output SALE may be OR compromised DISTRIBUTION due yyPatient-triggered (assist) breaths should have to increased mean airway pressures and decreased minimal work if proper trigger sensitivity is set venous return. and adequate inspiratory gas flow is provided to

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© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-6 Learning, Advantages LLC and Disadvantages of Pressure Control-Continuous Mandatory NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Ventilation (PC-CMV) (Continued) Assist-control PCV is relatively easy to understand overdistention (aka volume trauma), cyclic alveolar and apply. expansion and collapse (aka atelectrauma), or in- Mode is well-suited© Jones for most & patients,Bartlett assuming Learning, LLCflammation associated with© Jonesmechanical & Bartlettventilation Learning, LLC (biotrauma). skilled cliniciansNOT and careful FOR monitoringSALE OR of DISTRIBUTIONdeliv- NOT FOR SALE OR DISTRIBUTION ered volumes. Patients may trigger the ventilator at a rapid rate resulting in respiratory alkalosis and patient– Disadvantages of PC-CMV ventilator asynchrony. Vt will vary with changes in compliance, resistance, Inappropriate inspiratory flow rates that do not ©or Jones patient &effort. Bartlett Learning, LLC meet the ©patient’s Jones inspiratory & Bartlett flow Learning, demand in LLC NOTyyDecreased FOR SALE compliance, OR DISTRIBUTION increased resistance, spontaneouslyNOT breathing FOR SALE patients OR may DISTRIBUTION increase the or decreased patient effort will reduce deliv- WOB. ered Vt. Pressure rise time or slope may be improperly set. yyIncreased compliance, decreased resistance, or Rise time allows the clinician to adjust the rate at © Jones & Bartlettincreased Learning, patient LLCeffort will increase delivered © Joneswhich & inspiratoryBartlett Learning,gas flow increases LLC from baseline NOT FOR SALE Vt.OR DISTRIBUTION NOT FORto peak SALE flow atOR the DISTRIBUTION beginning of the inspiratory

yyCareful monitoring of exhaled Vt is required to phase. avoid inadvertent hyperventilation or hypoven- yyIf inspiratory flow exceeds patient demand, a tilation associated with changes in pulmonary pressure spike may occur early in the inspiratory mechanics or© patient Jones effort. & Bartlett Learning, LLCphase. Adjustment of the© riseJones time can& Bartlett eliminate Learning, LLC a pressure spike at the beginning of inspiration Because Vt is determinedNOT FOR by theSALE pressure OR gradi- DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ent (ΔP = PIP – PEEP), increases in PEEP without due to inappropriately high initial machine flow increases in PIP will decrease ΔP and decrease de- rates. livered Vt. Most ventilators make this adjustment yyIf inspiratory flow is reduced to the point at automatically (i.e., PC is maintained at the set value which patient demand exceeds machine flow, © aboveJones PEEP). & Bartlett Learning, LLC the pressure© Jones waveform & Bartlett will be deformed. Learning, Adjust LLC- NOTNo guaranteed FOR SALE minimum OR DISTRIBUTION minute ventilation (V˙e) ment ofNOT rise timeFOR can SALE increase OR inspiratory DISTRIBUTION flow because Vt may change due to changes in compli- to meet or exceed patient demand. ance, resistance, or patient effort. Assist-control PC ventilation may be poorly toler- Improper trigger sensitivity may increase the WOB. ated in patients who are awake, anxious, or in pain; © Jones & BartlettInadequate Learning, inspiratory LLC flow rates may increase the© Jonesthis &may Bartlett result in theLearning, patient fighting LLC the ventilator. NOT FOR SALEWOB OR in DISTRIBUTIONspontaneously breathing patients and re-NOT FORInadequate SALE expiratory OR DISTRIBUTION times may result in auto sult in patient–ventilator asynchrony. PEEP, particularly in patients with obstructive lung High mean airway pressures may reduce venous disease. return and impede cardiac output in hemodynami- Controlled ventilation (time-triggered PC-CMV) requires apnea. cally unstable patients.© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Pressure-controlNOT inverse-ratio FOR SALE ventilation OR (PC-IRV) DISTRIBUTION yySedative and paralytic drugsNOT may FOR be required. SALE OR DISTRIBUTION will further increase mean airway pressure and may yyParalytic drugs should not be administered alone reduce venous return and cardiac output. PC-IRV and require the addition of sedatives for pain may also cause autoPEEP due to short expiratory and anxiety. times resulting in further decreases in venous re- Development of ventilatory muscle weakness © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC turn and impairment of cardiac output. and atrophy is associated with controlled ven- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION PIP and Pplateau > 28 to 30 cm H2O may result in tilation, prolonged use of sedatives, and use of barotrauma (e.g., pneumothorax, pneumomedi- neuromuscular-blocking agents. astinum, pneumoperitoneum, and subcutaneous Pressure control is a less familiar type of ventilation emphysema) or VILI. VILI is caused by alveolar for some clinicians (as compared volume control). © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones &augmentation Bartlett Learning, (e.g., pressure LLC support or automatic tube© JonesThe addition & Bartlett of PSV Learning, or ATC will LLCreduce the WOB, but compensation). PEEP/CPAP may be added to provide NOTincrease FOR SALE mean airway OR DISTRIBUTIONpressure, which may reduce ve- NOT FOR SALEan elevated OR baseline DISTRIBUTION pressure. VC-IMV probably was nous return and impair cardiac output in hemodynami- the most popular and widely used mode of ventilation cally unstable patients. As noted above, when the level in United States from the late 1970s through the 1990s, of ventilatory support provided using IMV is decreased and most clinicians from that era have had a great deal to about 50% that needed for full ventilatory support, of experience in the ©use Jones of IMV and/or& Bartlett SIMV. Learning, LLCthe patient’s WOB can approach© Jones that of spontaneous& Bartlett Learning, LLC SIMV is currentlyNOT available FOR as SIMV SALE volume OR control DISTRIBUTION unsupported breathing. Also,NOT as noted, FOR VC-IMV SALE may OR DISTRIBUTION with pressure support or tube compensation (Covidien PB prolong ventilator weaning and discontinuance as com- 840 and PB 980), SIMV and SIMV with automatic tube pared to spontaneous breathing trials (SBTs) or PSV. compensation (Dräger Evita XL), volume-control SIMV When used to provide partial ventilatory support, (Evita Infinity V500), and SIMV and SIMV with tube sudden hypoventilation or apnea may result in an acute resistance© Jones compensation & Bartlett (Hamil Learning,ton G-5). LLC The Maquet respiratory ©acidosis. Jones Lastly, & Bartlett some patients Learning, who are LLC Servo-iNOT and FOR Servo-u SALE also featureOR DISTRIBUTION SIMV (volume control). experiencingNOT rapid FOR shallow SALE breathing OR may DISTRIBUTION continue to IMV was originally advanced as a preferred mode of make respiratory efforts throughout the mandatory ventilation because IMV was thought to result in more breath cycle resulting in an increase in WOB and rapid ventilator weaning. It has subsequently become patient–ventilator asynchrony apparent that when the support level approaches 50% of Automated modes of ventilation that provide a form © Jones & thatBartlett required Learning, for full ventilatory LLC support, the patient’s © Jonesof VC &IMV Bartlett include mandatoryLearning, minute LLC volume ventila- NOT FOR SALEWOB during OR DISTRIBUTIONVC-IMV can approach that of unsup- NOTtion, FOR mandatory SALE ORminute DISTRIBUTION volume ventilation with auto- ported spontaneous ventilation. Put another way, the matic tube compensation, mandatory minute volume degree of ventilatory muscle rest with VC-IMV is not ventilation with pressure-limited ventilation, and man- proportional to the level of ventilatory support pro- datory minute volume ventilation with pressure-limited vided.29 Today, it generally is accepted that VC-IMV ventilation and automatic tube compensation avail- may prolong ventilator© Jonesweaning as& comparedBartlett toLearning, other LLCable with the Dräger Evita XL© and Jones Evita Infinity& Bartlett V500. Learning, LLC methods (e.g., spontaneousNOT FOR breathing SALE trials OR [SBTs] DISTRIBUTION or Automode (available with theNOT Maquet FOR Servo-i SALE and OR DISTRIBUTION pressure support).26,29 Servo-u) also provides a form of VC-IMV. These newer Advantages of IMV include reduced mean airway modes of ventilation are discussed later in this chapter. pressures (as compared to VC-CMV); maintenance of Box 6-7 summarizes the advantages and disadvantages ventilatory muscle activity, strength, and coordination; of VC-IMV. and reduction in the need for sedation or administration © Jones & Bartlett Learning, LLC Pressure Control-Intermittent© Jones & Bartlett Mandatory Learning, Ventilation LLC of paralyticNOT FOR drugs. SALE There isOR some DISTRIBUTION evidence that the lower NOT FOR SALE OR DISTRIBUTION mean airway pressures associated with VC-IMV may be Pressure control-intermittent mandatory ventilation helpful in maintaining cardiac output and blood pressure (PC-IMV) intersperses mandatory pressure-control in some patients.26 During IMV, the patient continues to breaths with spontaneous breaths. The pressure-control breathe spontaneously interspersed with mandatory ma- breaths may be time or patient triggered and are pres- © Jones & chineBartlett breaths Learning, and spontaneous LLC breathing is thought to be© Jonessure limited & Bartlett and time Learning, cycled to expiration. LLC Spontan- more physiologic than positive pressure breathing. The eous breaths may be provided with or without pressure NOT FOR SALElevel of ventilatoryOR DISTRIBUTION support provided can be easily titratedNOT augmentation FOR SALE (e.g., OR pressure-support DISTRIBUTION ventilation [PSV] up and down based on the patient’s needs by simply in- or automatic tube compensation [ATC]. Fio2 is selected creasing or decreasing the mandatory rate. The level of and PEEP/CPAP may also be employed. The respiratory support provided can range from full ventilatory support, care clinician typically sets the pressure-control level, to partial support, to ©no Jonessupport, &depending Bartlett on Learning,the set LLCinspiratory time, and mandatory© Jones rate. The & clinicianBartlett also Learning, LLC mandatory (machine) rate. Rapidly breathing patients will set the trigger sensitivity and inspiratory rise time may adapt more readilyNOT to IMV, FOR without SALE the OR problem DISTRIBUTION of for the mandatory pressure-controlNOT FORbreaths. SALE For spon- OR DISTRIBUTION triggering mandatory breaths at a rapid rate resulting in taneous breaths, the clinician may add pressure support a respiratory alkalosis, which may occur with patient- or automatic tube compensation. Minimal PEEP/CPAP triggered VC-CMV. VC-IMV may improve patient toler- (3 to 5 cm H2O) generally is used to maintain FRC and ance© andJones patient–ventilator & Bartlett synchrony Learning, as compared LLC to provide physiologic© Jones PEEP. & BartlettHigher PEEP Learning, levels may LLCbe VC-CMVNOT FOR and the SALE development OR DISTRIBUTION of autoPEEP is less likely. required in NOTpatients FOR with SALEhypoxemic OR respiratory DISTRIBUTION failure. Disadvantages of VC-IMV include the WOBI associ- Pressure-control SIMV is currently available as ated with endotracheal and tracheostomy tubes during SIMV pressure control with pressure support or tube spontaneous breathing requiring the addition of PSV compensation (Covidien PB 840 and PB 980), PCV+ or automatic tube compensation (ATC). Spontaneous with pressure support or automatic tube compensation © Jones & breathingBartlett with Learning, high ventilatory LLC workloads may result in© Jones(Dräger & Evita Bartlett XL), pressure-control Learning, LLC SIMV and pressure- + NOT FOR SALEventilatory OR muscle DISTRIBUTION fatigue and dysfunction, which may NOTcontrol FOR SIMVSALE (EvitaOR DISTRIBUTION Infinity V500), and pressure- prolong the need for mechanical ventilatory support. control SIMV with pressure support or tube resistance

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© Jones & Bartlett Learning, LLC © Jones & BartlettBox 6-7 Learning, Advantages LLC and Disadvantages of VC-IMV NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION VC-IMV intersperses volume-targeted mandatory No need for excessive sedation or administration of breaths with spontaneous breathing. Mandatory breaths neuromuscular-blocking agents. may be time or patient triggered in the case of syn- Patients who rapidly trigger the ventilator in the chronized intermittent mandatory ventilation (SIMV). VC-CMV mode, resulting in hyperventilation and © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Pressure augmentation in the form of pressure support respiratory alkalosis, may benefit from a trial of or automatic tube compensationNOT FOR SALEmay be providedOR DISTRIBUTION to VC-IMV. NOT FOR SALE OR DISTRIBUTION overcome the imposed work of breathing (WOBI) asso- Development of autoPEEP may be less likely. ciated with endotracheal and tracheostomy tubes. PEEP/ CPAP may be added in order to improve oxygenation, Disadvantages of VC-IMV increase© Jones FRC, & and Bartlett prevent cyclicLearning, alveolar LLCrecruitment– Patients requiring© Jones full & ventilatory Bartlett support Learning, and LLC constant tidal volume delivery may do better on derecruitmentNOT FOR SALEas sometimes OR DISTRIBUTION seen in patients with NOT FOR SALE OR DISTRIBUTION severe hypoxemic respiratory failure (e.g., ARDS). VC-CMV. Imposed work of breathing (WOB ) due to the arti- Advantages of VC-IMV I Incorporates spontaneous breathing that maintains ficial airway during spontaneous breathing may be high. © Jones & Bartlettventilatory Learning, muscle activity LLC and may help maintain© Jones & Bartlett Learning, LLC ventilatory muscle strength and coordination. The addition of PSV or ATC to overcome WOBI in- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Incorporation of spontaneous breathing allows for creases mean airway pressure. more physiologic alveolar and intrathoracic pres- Spontaneous breathing with high ventilatory sures during spontaneous breaths and lower mean workloads may result in ventilatory muscle fa- airway pressures (as compared to VC-CMV). tigue, especially in patients with rapid shallow breathing and impaired pulmonary mechanics Mandatory respiratory© Jones rate &can Bartlett be easily titratedLearning, LLC © Jones & Bartlett Learning, LLC (e.g., reduced compliance, increased resistance). up and down toNOT vary the FOR level SALE of support OR provided DISTRIBUTION NOT FOR SALE OR DISTRIBUTION based on the patient’s needs. With partial ventilatory support and lower set mandatory rates (f 8 to 10 breaths/min) acute re- May provide partial or full ventilatory support, de- < pending on the set mandatory rate. spiratory acidosis may occur if the patient becomes apneic or hypoventilates. © yJonesyLevel of & support Bartlett provided Learning, can be easily LLC titrated © Jones & Bartlett Learning, LLC With lower mandatory rates (f 6 to 8 breaths/ NOTfrom FOR full SALE ventilatory OR support DISTRIBUTION (mandatory rate ≥ NOT FOR SALE OR< DISTRIBUTION 10 to 12 breaths/min) to no ventilatory support min or 50% of the full ventilatory support value) WOB can approach that of spontaneous (mandatory rate = 0). breathing. yyLower levels of support may be beneficial in The degree of respiratory muscle rest during © Jones & Bartlettcertain Learning, patients to LLC maintain cardiac output and© Jones & Bartlett Learning, LLC blood pressure. VC-IMV is not proportional to the level of ventila- NOT FOR SALE OR DISTRIBUTION NOT FORtory support SALE provided. OR DISTRIBUTION Patients often adjust easily to IMV, which may improve patient tolerance and patient–ventilator Some patients have difficulty adjusting to the venti- synchrony. lator and their spontaneous breathing pattern may conflict with the ventilator settings. PSV or ATC may be added to overcome the WOBI associated with endotracheal© Jones or & tracheostomy Bartlett Learning, tubes. LLCVC-IMV may prolong ventilator© Jones weaning. & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

compensation (Hamilton G-5). The Maquet Servo-i stable Vt delivery include SIMV volume control plus, and Servo-u also feature SIMV (pressure control). SIMV volume control plus with pressure support, and ©There Jones are several & Bartlett more exotic Learning, PC-IMV LLCvariations SIMV volume© Jonescontrol plus & Bartlettwith tube compensationLearning, (Co-LLC thatNOT incorporate FOR SALEmultiple OR targeting DISTRIBUTION schemes (e.g., servo, vidien PB 840NOT and FORPB 980), SALE SIMV ORwith DISTRIBUTIONautoflow (Dräger adaptive, and adaptive with servo). Recall that adaptive Evita XL), VC-SIMV with autoflow and PC-SIMV with targeting schemes can maintain a stable tidal volume volume guarantee (Evita Infinity V500), and SIMV by adjusting pressure-control levels between breaths as pressure-regulated volume control (Maquet Servo-i and lung mechanics or inspiratory patient effort vary. Servo- Servo-u). These modes use pressure control with auto- © Jones & targetingBartlett schemes Learning, vary the LLC support provided by the © Jonesmatic adjustment& Bartlett to Learning, achieve a target LLC Vt. Other forms NOT FOR SALEventilator OR proportional DISTRIBUTION to inspiratory effort. Forms of NOTof FOR PC-IMV SALE include OR bilevel DISTRIBUTION with pressure support, bilevel PC-IMV that incorporate adaptive targeting to maintain with tube compensation (Covidien PB 840 and PB 980)

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© Jones &and Bartlett APRV and Learning, APRV with LLC tube compensation (Dräger © Jonesand patient–ventilator & Bartlett Learning, synchrony. LLCPatients with rapid Evita XL and Evita Infinity V500). NOTshallow FOR SALEbreathing OR may DISTRIBUTION have difficulty tolerating PC- NOT FOR SALEPC-IMV OR incorporates DISTRIBUTION the advantages and disadvan- IMV and at lower mandatory rates, sudden apnea or tages of pressure-control ventilation with IMV. As with hypoventilation can result in acute respiratory acidosis. PC-CMV, mandatory breath Vt will vary with changes It should also be recalled that at low mandatory IMV in patients’ pulmonary mechanics and inspiratory ef- rates, WOB can approach that of spontaneous unsup- fort. PC-IMV will allow© Jones the clinician & Bartlett to set an Learning, appro- LLCported breathing. Appropriate© levelsJones of PSV & Bartlett should help Learning, LLC priate and safe inspiratoryNOT FORpressure SALE to maintain OR DISTRIBUTION Pplateau reduce WOB when low mandatoryNOT ratesFOR are SALE employed. OR DISTRIBUTION ≤ 28 to 30 cm H2O and avoid ventilator-induced lung Like VC-IMV, PC-IMV has not been shown to be a su- injury. Tidal volume for pressure-control breaths is de- perior mode for ventilator weaning and may prolong the termined by the pressure gradient (ΔP = PIP – PEEP), weaning process as comparted to PSV or SBTs.29 patient effort, inspiratory time (TI), and pulmonary mechanics© Jones (compliance & Bartlett and resistance).Learning, Normally LLC the Pressure Control-Continuous© Jones & Bartlett Learning, LLC PIPNOT is adjusted FOR to SALE achieve OR a mandatory DISTRIBUTION breath tidal vol- SpontaneousNOT Ventilation FOR SALE OR DISTRIBUTION ume in the range of 6 to 8 mL/kg IBW, although larger tidal volumes may be appropriate for some patients. Forms of pressure control-continuous spontanteous venti- Inspiratory time (TI) may also affect Vt provided dur- lation (PC-CSV) include pressure support, automatic tube ing pressure-control breaths. Typical adult TI for manda- compensation and continuous positive airway pressure. © Jones & toryBartlett pressure-control Learning, breaths LLC is in the range of 0.6 to 1.0 © JonesWhile &pressure Bartlett support Learning, and CPAP canLLC be used with IMV, they may also be used as stand alone, primary modes. NOT FOR SALEseconds, OR although DISTRIBUTION many patients do well with a slightly NOT FOR SALE OR DISTRIBUTION longer TI (e.g., 0.8 to 1.2 seconds). On initial setup, inspi- Continuous Spontaneous Ventilation (CSV) ratory time is usually adjusted so that inspiratory flow declines to zero at end inspiration. This should optimize Vt Some modes of ventilation allow for spontaneous delivery (at the set pressure-control value) and improve breathing through the ventilator circuit. Spontaneous distribution of inspired© gas.Jones The &decreasing Bartlett flow Learning, wave- LLCbreathing during mechanical© ventilatory Jones support& Bartlett can be Learning, LLC defined by the method a breath is triggered and cycled. form provided with pressureNOT FOR control SALE will vary OR inspiratory DISTRIBUTION NOT FOR SALE OR DISTRIBUTION flow with patient inspiratory effort, which may improve With IMV, some breaths are mandatory (i.e., time or patient comfort and patient–ventilator synchrony. The patient triggered, but machine cycled) and some breaths square wave-like pressure waveform provided will in- are spontaneous (i.e., patient triggered and patient cy- crease mean airway pressure and may improve distribu- cled). With continuous spontaneous ventilation (CSV) tion© of Jones inspired & gases Bartlett and oxygenation. Learning, As with LLC PC-CMV, every breath© is Jones patient triggered& Bartlett and patientLearning, cycled. LLC Put another way, every breath is spontaneous. Spontaneous higherNOT mean FOR airway SALE pressures OR mayDISTRIBUTION impair venous return NOT FOR SALE OR DISTRIBUTION and cardiac output in hemodynamically unstable pa- breaths during mechanical ventilation can be provided tients. That said, the inclusion of IMV should lower mean with or without pressure augmentation. The most com- airway pressures compared to PC-CMV. Pressure rise mon forms of pressure augmentation are PSV and auto- time or slope should be adjusted to ensure inspiratory matic tube compensation (ATC). CPAP can be defined as spontaneous breathing with an elevated baseline © Jones & flowBartlett provided Learning, meets or exceeds LLC the patient’s inspiratory© Jones & Bartlett Learning, LLC demand. Recall, however, that too rapid rise times can re- pressure. Thus, during inspiration CPAP also provides a NOT FOR SALEsult in a ORpressure DISTRIBUTION spike at the beginning of inspiration. NOTform FOR of SALEinspiratory OR pressure DISTRIBUTION augmentation. PC-IMV can provide full or partial ventilatory sup- Pressure-Support Ventilation (PSV) port by adjusting the mandatory rate. For full ventilatory support, pressures generally are adjusted to achieve PSV provides patient-triggered, pressure-limited, flow- an acceptable Vt and© mandatory Jones & IMV Bartlett rate is set Learning, in the LLCcycled ventilation. When used© as Jones a primary & mode Bartlett of Learning, LLC range of 12 to 20 breaths/min. Partial ventilatory sup- ventilation, PSV is a form of pressure control-continuous port is provided by usingNOT a lowerFOR IMV SALE rate. OR Because DISTRIBUTION PC- spontaneous ventilation (PC-CSV).NOT EveryFOR breath SALE is pa OR- DISTRIBUTION IMV incorporates spontaneous breathing, ventilatory tient triggered and patient cycled and inspiratory pres- muscle activity is maintained, which may help preserve sure augmentation is provided with every breath. Thus, ventilatory muscle strength and coordination. Allowing during PSV patients can vary their respiratory rate, the© patient Jones to spontaneously& Bartlett Learning,breathe between LLC pressure- inspiratory ©flow, Jones inspiratory & Bartlett time, and Learning, tidal volume. LLCThe controlNOT breaths FOR maySALE have OR other DISTRIBUTION physiologic benefits respiratory NOTcare clinician FOR setsSALE the triggerOR DISTRIBUTION sensitivity and (e.g., more normal alveolar and intrathoracic pressures pressure-support level. Most modern critical care ven- during spontaneous breaths). Pressure support pro- tilators also allow the clinician to set the inspiratory rise vided during spontaneous breaths should be adjusted time and flow termination criteria (i.e., cycle sensitivity) to minimize the WOBI associated with the artificial during PSV. The level of pressure augmentation (i.e., © Jones & airway.Bartlett Recall, Learning, however, that LLC PSV and ATC will increase© Jonespressure-support & Bartlett level) Learning, provided will LLC vary, depending on NOT FOR SALEmean airway OR DISTRIBUTIONpressure. Some patients adjust easily to NOTthe FOR clinical SALE goals. OR As the DISTRIBUTION pressure-support level increases, IMV, which may further improve patient tolerance so will the patient’s spontaneous tidal volume. Assuming

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Flow (L/min) Flow –40 –60© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 2 46810 12 14 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

O) 24 2 20 16 12 © Jones & Bartlett8 Learning, LLC © Jones & Bartlett Learning, LLC 4 Tr igger NOT FOR SALE0 OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION essure (cm H Pr essure 2 4 6810 12 14 600 500 400 © Jones & Bartlett Learning,300 LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION200 NOT FOR SALE OR DISTRIBUTION 100 Volume (mL) Volume 0 2 468101214 Time (s) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 6-3 Pressure Support.NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

adequate inspiratory flow rates are provided, as PSV for signs of distress (e.g., f > 30 to 35 breath/min, Spo2 increases, tidal volume increases and WOB declines. < 90%, heart rate [HR] > 120 to 140 bpm, systolic blood Figure 6-3 illustrates patient-triggered, pressure-limited, pressure [BP] < 90 or > 180 mmHg). If the patient dis- flow-cycled© Jones pressure-support & Bartlett Learning, ventilation (aka LLC PC-CSV). plays signs of© distress,Jones PSV & Bartlett is returned Learning, to its previous LLC NOTDuring FOR PSV, expiration SALE OR may DISTRIBUTION be passive to ambient level. In theNOT absence FOR of distress, SALE reductions OR DISTRIBUTION in the level pressure (0 cm H2O baseline) or to an elevated baseline of PSV continue to the point at which extubation is con- pressure (PEEP/CPAP). Modest levels of pressure sup- sidered (e.g., PSV of 5 to 8 cm H2O is well tolerated). port (5 to 15 cm H2O) can be used to overcome the However, if full ventilatory support only requires 10 WOBI due to the ventilator circuit and artificial airway. cm of H2O, then PSV at 5 cm is not truly considered a © Jones & LowBartlett levels ofLearning, PSV (e.g., 5 LLCto 8 cm H2O) are often com- © JonesSBT and & someBartlett clinicians Learning, suggest a LLC trial of ATC without bined with CPAP during IMV and during spontaneous PSV to assess the patients readiness for extubation. NOT FOR SALEbreathing OR trials DISTRIBUTION (SBTs) to evaluate the patient’s readi- NOT FORTo summarize, SALE OR PSV DISTRIBUTION may be used as a standalone ness for ventilator discontinuance and extubation. mode or in conjunction with IMV. When used with While commonly used in conjunction with IMV, PSV IMV, low levels of PSV are often employed to reduce or can also be used as a primary mode of ventilation. As a eliminate the WOBI of spontaneous breaths in between primary mode of ventilation,© Jones PSV & may Bartlett improve Learning, patient– LLCmandatory breaths. PSV values© neededJones to & eliminate Bartlett the Learning, LLC ventilator synchrony and patient comfort. When used as WOBI will vary with the patient’s ventilatory pattern and the primary mode of NOTventilation, FOR the SALE pressure-support OR DISTRIBUTION endotracheal or tracheostomyNOT tube diameterFOR SALE but usu OR- DISTRIBUTION level generally is adjusted to achieve a tidal volume in the ally are in the range of 5 to 15 cm H2O. PSV may also be range of 4 to 8 mL/kg IBW with the patient-triggered used during SBTs, often in combination with CPAP, to respiratory rate ≤ 25 breaths/min. Generally speaking, assess the patient’s readiness for ventilator discontinu- as the© Jones pressure-support & Bartlett level Learning,increases, WOB LLC decreases. ance. PSV is© sometimes Jones & used Bartlett as the primary Learning, mode ofLLC NOTWhile FORoften employed SALE OR during DISTRIBUTION SBTs to overcome the ventilation NOTand may FOR improve SALE patient–ventilator OR DISTRIBUTION syn- WOBI due to the endotracheal or tracheostomy tube, chrony and comfort, reduce the WOB, and provide an PSV may also be used as an alternative ventilator wean- alternative method for ventilator weaning. When used ing method. When used as a primary weaning method, as a primary, standalone mode PSV is a form of PC-CSV. PSV generally is initiated at a relatively high level to Automatic tube compensation (ATC) is designed © Jones & achieveBartlett an adequateLearning, Vt and LLC respiratory rate (f). When © Jonesto overcome & Bartlett the WOB Learning,I due to an endotrachealLLC tube NOT FOR SALEthe patient OR meets DISTRIBUTION readiness criteria, PSV is reduced 2 toNOT or FOR tracheostomy SALE ORtube DISTRIBUTIONduring spontaneous breathing. 4 cm H2O in a stepwise fashion followed by assessment ATC automatically applies inspiratory positive pressure

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Flow (L/min) Flow –30 –40 –50© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE2 OR468 DISTRIBUTION 10 12NOT 14FOR SALE OR DISTRIBUTION

O) 24 2 20 16 12 8 © Jones & Bartlett4 Learning, LLC © Jones & Bartlett Learning, LLC 0 NOT FOR SALE (cm H Pr essure OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 2 468101214 600 500 400 © Jones & Bartlett Learning,300 LLC © Jones & Bartlett Learning, LLC 200

NOT FOR SALE OR DISTRIBUTION (mL) Volume 100 NOT FOR SALE OR DISTRIBUTION 0 2 468101214 Time (s)

FIGURE 6-4 Continuous ©Positive Jones Airway & Pressure. Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION proportional to the measured resistance of the artifi- tube. Like PEEP, CPAP increases mean airway pressure, cial airway. The respiratory care clinician sets the per- mean intrathoracic pressure, and FRC. Figure 6-4 illus- centage of compensation to be applied, ranging from trates pressure, volume, and flow curves seen with CPAP. partial© Jones to full compensation. & Bartlett Learning,While ATC does LLC reduce CPAP may© increaseJones the& Bartlettlung surface Learning, area for gas LLC theNOT patient’s FOR WOB, SALE it has ORnot beenDISTRIBUTION shown to improve exchange, improveNOT FOR oxygenation, SALE and OR help DISTRIBUTION prevent al- patient outcomes.2 ATC incorporates a set point with veolar collapse and atelectasis. CPAP may be useful to servo-(s,r) targeting scheme and is commonly used with maintain alveolar recruitment in patients with acute re- IMV.4 Recall that servo-targeting schemes vary the out- strictive lung disease (e.g., mild to moderate pulmonary put of the ventilator automatically following a varying edema, parenchymal lung injury).2 With CPAP, pres- © Jones & inputBartlett and can Learning, vary support LLC provided proportional to © Jonessure is & elevated Bartlett during Learning, inspiration LLC and expiration, thus NOT FOR SALEinspiratory OR effort. DISTRIBUTION Setpoint targeting simply refers to theNOT providing FOR SALE a form OR of inspiratory DISTRIBUTION pressure augmentation ability of the clinician to set specific parameters (e.g., that may reduce the WOB during spontaneous ventila- level of compensation provided). Ventilators that offer tion. CPAP is often used during spontaneous breathing ATC include the Covidien PB 840 and PB 980 (as tube trials (SBTs) for evaluation of ventilator discontinuance compensation), Dräger Evita XL and Evita Infinity V500 and extubation. CPAP may also be useful in maintain- (as automatic tube compensation© Jones &), andBartlett Hamil Learning,ton LLCing FRC in intubated patients,© who Jones may otherwise & Bartlett have Learning, LLC G-5 (as tube resistanceNOT compensation FOR SALE). When OR used DISTRIBUTION alone slight reductions in FRC due NOTto the lossFOR of glotticSALE func- OR DISTRIBUTION (e.g., IMV rate = 0) ATC is a form of PC-CSV. tion; thus, CPAP levels of 3 to 5 cm H2O for intubated patients may be considered physiologic. CPAP should Continuous Positive Airway Pressure be used cautiously in patients with obstructive lung disease and those with hemodynamic instability. CPAP© Jones describes & spontaneous Bartlett Learning, breathing at aLLC constant © Jones & Bartlett Learning, LLC elevatedNOT pressure. FOR SALE With CPAP, OR DISTRIBUTIONthe patient initiates and Other ModesNOT of FOR Ventilation SALE OR DISTRIBUTION terminates each breath. CPAP may be used during continuous spontaneous ventilation (CSV) or with IMV. There are a number of alternative modes of ventilation CPAP may also be combined with PSV. CPAP may be which incorporate feedback mechanisms to adjust the provided through the ventilator or independently us- level or type of support provided. In addition, APRV © Jones & ingBartlett a high-flow, Learning, blended andLLC humidified gas source and© Jonesand high & Bartlettfrequency ventilationLearning, provide LLC alternative NOT FOR SALEa PEEP valve.OR DISTRIBUTION CPAP may be provided by a well-fitted NOTmodes FOR whichSALE may OR be usefulDISTRIBUTION for certain patients (e.g., facemask or invasively, via endotracheal or tracheostomy severe ARDS).

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Adaptive Pressure Control © Jones & Bartlett Learning, LLC © Jonestargeting & Bartlettscheme. As Learning, a form of APC, LLC PRVC provides relatively stable tidal volume delivery with changes in NOT FOR SALEAdaptive OR pressure DISTRIBUTION control (APC) provides an adaptive NOT FOR SALE OR DISTRIBUTION feedback mechanism for pressure control or pressure compliance, resistance, or patient effort. Patients may support. With APC the desired tidal volume (Vt) is trigger the ventilator (aka assist breaths) and set their set but the breath type is pressure control or pressure own rate. In the absence of a patient trigger within support. The ventilator then automatically adjusts the the time interval provided, the ventilator will initiate a pressure level from breath© Jones to breath & Bartlett to achieve Learning,the LLCtime-triggered breath (aka control© Jones breath). & IfBartlett the deliv- Learning, LLC targeted Vt. This allowsNOT the FOR ventilator SALE to ORmaintain DISTRIBUTION a ered Vt for a breath is less thanNOT the FORtarget, SALEthe pressure- OR DISTRIBUTION control value will automatically increase for the next relatively stable Vt in the face of changes in compliance, breath. If Vt is greater than target, the pressure-control resistance, or patient effort. If delivered Vt decreases, the ventilator automatically increases the pressure pro- value will automatically decrease for the next breath. vided and vice versa. On the other hand, if patient de- As noted earlier, adaptive targeting has the advan- mand© Jonesand associated & Bartlett effort increases Learning, resulting LLC in a larger tage of allowing© Jones for automatic & Bartlett adjustments Learning, in pressure LLC thanNOT desired FOR Vt, SALEthe ventilator OR DISTRIBUTIONautomatically decreases control to achieveNOT FORa volume SALE target. OR Adaptive DISTRIBUTION targeting, the pressure-control level, which may be inappropriate. however, can make inappropriate ventilator adjustments APC provides many of the advantages of in cases where algorithm assumptions are incorrect, or pressure-control ventilation while maintaining a rela- the assumptions do not match the patient’s physiology. tively stable clinician-selected Vt. Decreases in compli- For example, an increase in patient effort may be inter- © Jones & ance,Bartlett increases Learning, in resistance, LLC or reductions in patient © Jonespreted & as Bartlettan increase Learning, in compliance. LLC This may result in NOT FOR SALEeffort willOR cause DISTRIBUTION the ventilator to increase the pressure NOTan FOR inappropriate SALE OR decrease DISTRIBUTION in support. automatically. Clinicians must be aware, however, Functionally, the Servo-i and Servo-u ventilators in the that peak inspiratory pressures (PIP) and plateau pres- PRVC mode will deliver a test breath Vt with an inspiratory breath hold to measure the plateau pressure (Pplateau). sures (Pplateau) may rise above acceptable levels as the ventilator attempts to automatically maintain a target The measured plateauP pressure is then used for the next Vt in the face of changes© Jones in ventilatory & Bartlett mechanics Learning, or LLCbreath and the resultant exhaled© JonesVt is compared & Bartlett to the Learning, LLC decreased patient effort.NOT OnFOR the otherSALE hand, OR increasing DISTRIBUTION target Vt. The pressure is thenNOT regulated FOR to SALE provide ORthe DISTRIBUTION patient effort may result in an inappropriate decreased clinician-set Vt from breath to breath. The pressure will ± level of support for patients in distress. increase or decrease in increments of 3 cm H2O per Manufacturers’ names for adaptive pressure control breath as needed to achieve the target tidal volume. The include pressure-regulated volume control (PRVC) pro- pressures possible, however, cannot exceed the clinician- vided© Joneswith the Maquet& Bartlett Servo-i Learning, and Servo-u LLC (see below), selected peak© pressureJones alarm & Bartlett setting minus Learning, 5 cm H2 OLLC (e.g., if the peak pressure alarm is set at 30 cm H2O, the auto-flowNOT FORprovided SALE with theOR Dräger DISTRIBUTION Evita XL and Evita NOT FOR SALE OR DISTRIBUTION30 Infinity V500, volume control plus (Covidien PB 840 and ventilator cannot increase PIP beyond 25 cm H2O). PB 980), and adaptive pressure ventilation (Hamilton As with other forms of PC-CMV, PRVC incorporates G5 and C-3). We will discuss a few of these versions of a decreasing flow waveform and square wave pressure APC below. waveform. As compared to VC-CMV with fixed inspiratory flow rates, PRVC shares many of the advantages of © Jones & Pressure-RegulatedBartlett Learning, Volume LLC Control © Jones & Bartlett Learning, LLC PC-CMV in that it may reduce the WOB and improve NOT FOR SALEPressure-regulated OR DISTRIBUTION volume control (PRVC) is a form ofNOT patient FOR comfort,SALE ORand increasedDISTRIBUTION mean airway pressure APC first introduced on the Servo 300 ventilator in the may improve oxygenation. Inspiratory gas flow varies 1990s. This form of APC is currently available on the with patient inspiratory effort, which may improve Maquet Servo-i and Servo-u and Yvaire AVEA ventila- patient–ventilator synchrony. tors as pressure-regulated© Jones volume & control. Bartlett PRVC Learning, pro- LLCAs described above, PRVC© is Jonesa form of & adaptive Bartlett pres- Learning, LLC vides volume-targeted pressure-control breaths using sure control (APC) that is available on several other an adaptive (a) targetingNOT scheme FOR that SALE automatically OR DISTRIBUTION ad- ventilators under different proprietaryNOT FOR names SALE (e.g., OR DISTRIBUTION justs the pressure between breaths to reach the targeted auto-flow: Dräger Evita XL and Evita Infinity V500, tidal volume in response to varying patient conditions. volume control plus: Covidien PB 840 and PB 980, and Delivered Vt is measured and compared with target adaptive pressure ventilation: Hamilton G5 and C-3). Vt and the pressure-control value is then gradually © Jones & Bartlett Learning, LLC Volume Support© Jones & Bartlett Learning, LLC increasedNOT FOR or decreased SALE until OR the DISTRIBUTION target Vt is reached. NOT FOR SALE OR DISTRIBUTION PRVC allows for patient-triggered or time-triggered Volume support (VS) is like PSV with the addition of a breaths (aka assist-control ventilation). PRVC with IMV clinician-set volume target. Like PSV, volume support is also offered with the Servo-i and Servo-u ventilators requires spontaneous breathing. All breaths are patient as SIMV pressure-regulated volume control. triggered, pressure limited, and flow cycled to expiration. © Jones & BartlettPRVC can Learning, be classified LLC as pressure control-contin- © JonesUpon initial& Bartlett setup the Learning, ventilator delivers LLC a test pulse at NOT FOR SALEuous mechanical OR DISTRIBUTION ventilation with adaptive targeting NOT10 FOR cm H SALE2O above OR PEEP DISTRIBUTION and measures compliance and (PC-CMVa) where the “a” notation indicates an adaptive exhaled Vt. The ventilator than automatically adjusts the

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pressure-support level up or down on a breath-to-breath patients may develop rapid shallow spontaneous breath- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,˙ LLC basis to achieve the clinician-selected tidal volume. NOTing, FOR which SALE can result OR inDISTRIBUTION high Ve but inadequate alveolar NOT FOR SALEVolume OR support DISTRIBUTION is a form of pressure-control ventila- ventilation. Recall that many patients in respiratory fail- tion with adaptive breath targeting. As described earlier, ure develop rapid shallow breathing patterns that main- adaptive breath targeting allows the ventilator to auto- tain a relatively high minute ventilation. This is especially matically vary pressure to achieve the desired Vt. Like true for patients with acute restrictive pulmonary dis- PSV, the patient triggers© Jones and cycles & Bartletteach breath; Learning, be- LLCease (e.g., severe pneumonia, ©ARDS). Jones For &example, Bartlett a very Learning, LLC = cause of this, VS canNOT be classified FOR SALEas a form OR of pressureDISTRIBUTION sick patient breathing 40 breaths/minNOT FOR with VSALEt 150 OR mL DISTRIBUTION control-continuous spontaneous ventilation, specifically would have a minute ventilation of 6 L/min: PC-CSV . With adaptive (a) breath targeting, however, a V˙e = Vt × f = 150 mL × 40 breaths/min = inappropriate changes may occur if algorithm assump- 6000 mL/min = 6 L/min tions are violated or do not match the patient’s actual physiology.© Jones For & example, Bartlett the Learning,ventilator cannot LLC distin- In such a© case, Jones the MMV & Bartlett system would Learning, assume thatLLC guishNOT between FOR changes SALE in OR patient DISTRIBUTION effort and changes in spontaneousNOT minute FOR ventilation SALE was OR adequate DISTRIBUTION and dial compliance; an increase in patient effort may be mis- back the mandatory IMV rate, even though very shallow interpreted as an improvement in compliance and the tidal volumes provide minimal effective alveolar venti- ventilator may decrease support inappropriately. lation due to dead space. Recall also that IMV has the In summary, volume support has many of the ad- potential to prolong ventilator weaning, and spontan- © Jones & vantagesBartlett of Learning,pressure support LLC but provides more stable © Joneseous breathing & Bartlett trials Learning, (SBTs) have supplantedLLC IMV as the NOT FOR SALEtidal volume OR deliveryDISTRIBUTION in the face of changes in compli- NOTmost FOR appropriate SALE OR approach DISTRIBUTION to ventilator discontinuance ance, resistance, or patient effort. Volume support can for most patients. 4,5 be classified as PC-CSVa. All breaths are initiated and MMV is currently available on the Dräger Evita XL terminated by the patient (i.e., patient triggered and and Evita Infinity V500 as mandatory minute volume flow cycled). In the absence of a patient trigger, no time- ventilation (VC-IMVa,s, that is, adaptive and set-point triggered breaths will© be Jones provided; & anBartlett apnea alarm Learning, and LLCbreath targeting) and mandatory© Jones minute &volume Bartlett with Learning, LLC backup apnea ventilationNOT mode FOR should SALE be employed.OR DISTRIBUTION pressure-limited ventilation (VC-IMVNOT FORda,s indicates SALE dualOR DISTRIBUTION For example, in the volume-support mode the Maquet adaptive and set-point breath targeting).31 Despite being Servo-i ventilator will automatically switch from volume available since the late 1970s, MMV has not been shown support to volume control in the event of apnea. to consistently improve ventilator weaning success as Volume support is available on the Servo-i, Servo-u, compared to newer techniques and has not been shown Covidien© Jones PB 840 & andBartlett PB 980, Learning, and Newport LLC e360. to improve ©other Jones important & Bartlett patient outcomes. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Mandatory Minute Ventilation (MVV) Adaptive Support Ventilation (ASV) Mandatory minute ventilation (MVV) is an older form Adaptive support ventilation (ASV) is a closed-loop, of automated ventilation that compares the patient’s automatic ventilation mode that combines aspects of ˙ © Jones & actualBartlett minute Learning, ventilation (VLLCe) to a targeted value and © Jonespressure & controlBartlett IMV Learning, with pressure LLC support (i.e., automatically increases or decreases the level of support PC-IMV) to achieve a target minute ventilation (V˙e). NOT FOR SALEprovided. OR As originallyDISTRIBUTION introduced in 1977, MMV was NOTASV FOR incorporates SALE OR optimal DISTRIBUTION targeting of both mandatory a form of intermittent mandatory ventilation that auto- and spontaneous breaths.4,5 With ASV the pressure- matically increased or decreased the mandatory breath control level is adjusted automatically to achieve a rate to achieve the desired minute ventilation. MMV was specific tidal volume (Vt) at a specific frequency for 4,5 initially introduced as© a Jonesform of automated & Bartlett ventilator Learning, LLCmandatory breaths. Target ©tidal Jones volume & for Bartlett spontane- Learning, LLC weaning. As the patient’s level of spontaneous ventilation ous breaths is based on respiratory system mechanics increased, the ventilatorNOT would FOR automatically SALE OR dial DISTRIBUTION back and target minute ventilation.NOT4,5 Mandatory FOR SALE breaths OR are DISTRIBUTION the number of mandatory breaths delivered. If the pa- time triggered at a preset frequency and inspiratory tient’s spontaneous ventilation decreased, the ventilator pressure and are time cycled to expiration (i.e., pressure would automatically increase the number of mandatory control). Spontaneous breaths are patient triggered and ˙ breaths© Jones provided & toBartlett maintain Learning,the desired V eLLC. Other forms flow cycled© to Jones expiration & (i.e.,Bartlett pressure Learning, support). LLC of MMV later introduced would vary the level of pressure Simply put, ASV allows for the delivery of patient- supportNOT provided FOR SALE (vs. IMV OR rate) DISTRIBUTION to maintain a stable V˙e. triggered pressure-supportedNOT FOR SALE spontaneous OR DISTRIBUTION breaths or Advantages of MMV include assuring a more stable time-triggered mandatory pressure-control breaths to level of ventilation during IMV in the face of changes achieve a minimum minute ventilation at an optimal level in patients’ spontaneous breathing; avoidance of epi- of WOB. The ventilator automatically adjusts the level of © Jones & sodesBartlett of acute Learning, hypoventilation; LLC and providing a smooth,© Jonessupport & provided Bartlett based Learning, on respiratory LLC system mechanics, systematic, automated method of weaning ventilatory targeted minute ventilation (V˙e), and clinician-selected NOT FOR SALEsupport. OR An importantDISTRIBUTION disadvantage of MMV is that NOTlevel FOR of support.SALE TargetOR DISTRIBUTION minute ventilation is calculated

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© Jones &by Bartlett the ventilator Learning, based on LLCthe patient’s ideal body weight© JonesTo initiate& Bartlett ASV the Learning, clinician enters LLC the patient’s ideal (IBW) at 0.1 L/min/kg (or 100 mL/min/kg). For example,NOT body FOR weight, SALE high OR pressure DISTRIBUTION limit, PEEP, Fio2, rise time, NOT FOR SALEa patient OR with DISTRIBUTIONan ideal body weight of 70 kg would have flow cycle, and percentage of predicted minute venti- a target minute ventilation of 7 L/min (V˙e = 0.1 L/min/ lation to support (i.e., 20% to 200%). The ventilator kg × 70 kg = 7 L/min). The clinician could then select to incorporates algorithms that automatically adjust the res- provide from 20% to 200% of the calculated V˙e. If 100% piratory rate, pressure limit, and tidal volume to optimize ˙ support was selected,© in Jones this example & Bartlett the target Learning,Ve would LLCthe patient’s WOB based on measurement© Jones & of Bartlett specific Learning, LLC be 7 L/min. A level ofNOT support FOR of up SALE to 200% OR could DISTRIBUTION be variables (e.g., flows, times, compliance,NOT FOR resistance, SALE ORand DISTRIBUTION selected for patients with increased ventilatory needs. expiratory time constant) to maintain an appropriate Examples of patients who may have increased ventilatory level of support based on calculated V˙e.32 The ventilator needs include those with sepsis, increased physiologic uses a test breath to calculate compliance, resistance, and dead space, or increased metabolic rate. Less than 100% autoPEEP. The ventilator automatically sets minimum support© Jones could be & selected Bartlett for ventilatorLearning, weaning. LLC and maximum© Jonesvalues for & V tBartlett, mandatory Learning, breath fre- LLC WithNOT ASV, FOR the SALE ventilator OR uses DISTRIBUTION an algorithm to de- quency, inspiratoryNOT FOR pressure, SALE and inspiratory/expiratory OR DISTRIBUTION termine the optimal breathing frequency (f) and tidal time. Vt is adjusted with changes in compliance to main- volume (Vt). The ventilator’s goal is to provide tidal vol- tain a lung-protective strategy. For example, a decrease umes and frequencies that are physiologically beneficial in compliance may result in a decrease in Vt. ASV auto- for the patient in terms of WOB. The optimal breathing matically adjusts mandatory breath frequency (f) and I:E © Jones & frequencyBartlett (f) Learning, to minimize LLC WOB based on the estimated© Jonesratio to & maintain Bartlett an expiratoryLearning, time LLC at least three time NOT FOR SALEdead space OR (Vd) DISTRIBUTION and measured expiratory time constantNOT constants FOR SALE in length OR and DISTRIBUTION reduce the risk of autoPEEP. is calculated.2 Ventilatory dead space (Vd) is estimated ASV will alter the amount of support provided to at 2.2 mL/kg IBW. Tidal volume (Vt) is calculated based achieve the target V˙e. With spontaneously breathing ˙ on the target Ve and optimal calculated breathing fre- patients, ASV will deliver patient-triggered, pressure- ˙ quency where Vt = Ve/f. The clinician sets the inspira- limited, flow-cycled pressure-support breaths while tory pressure-support© level,Jones rise &time, Bartlett and expiratory Learning, LLCmonitoring the patient’s lung© mechanics Jones and& Bartlett minute Learning, LLC cycle sensitivities forNOT spontaneous FOR SALEbreaths. OR DISTRIBUTIONventilation. If the level of spontaneousNOT FOR ventilation SALE is OR suf- DISTRIBUTION ficient to meet the target ˙e,V no mandatory breaths will be delivered. If the level of spontaneous ventilation is ˙ CLINICAL FOCUS 6-1 Estimated Minute insufficient to meet thee V , the ventilator will automatic- Volume and Dead Space Volume ally increase the level of support provided. A© patient Jones with & acuteBartlett respiratory Learning, failure is LLC to receive ASV can© be Jones an effective & Bartlett approach toLearning, ventilation inLLC patients with acute respiratory failure.2 Patients with adaptiveNOT FOR support SALE ventilation OR DISTRIBUTION (ASV). The clinician NOT FOR SALE OR DISTRIBUTION normal or near-normal lungs (e.g., opiod drug overdose calculates her ideal body weight at 70 kg. without aspiration) who require ventilatory support may 2 Question 1. Estimate the required minute receive unnecessarily large tidal volumes with ASV. ASV ventilation for this patient using the formula can adjust to changing lung compliance and patient in- © Jones & Bartlettintegrated Learning, into the ASV LLC system. © Jonesspiratory & Bartletteffort; however, Learning, automatic LLC adjustment may be The patient’s required minute ventilation (V˙ e) can inappropriate if algorithm assumptions are violated or if NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION5 be estimated using the following formula: they do not match the patient’s physiology. ASV while may provide a safe and effective method V˙ e = 100 mL/min/kg × IBW (kg). for automated ventilator weaning.32 Because of the al- Assuming IBW = 70 kg, this becomes: gorithms in play, patients with extended expiratory time constants (e.g., long expiratory time as seen in COPD) V˙ e = 100 mL/min/kg© Jones × 70 kg & = Bartlett 7000 mL/min Learning, or LLC © Jones & Bartlett Learning, LLC may receive larger tidal volumes and lower frequencies NOT 7 L/min. FOR SALE OR DISTRIBUTIONas compared to patients with NOTshorter FOR time expiratorySALE OR DISTRIBUTION constants (e.g., short expiratory time as may occur with Question 2. Estimate this patient’s dead space ARDS).26 ASV has not been shown to improve specific volume using the formula integrated into the clinically important patient outcomes.26 ASV system. ASV is available on the Hamilton G5, C-3, C-1, Ventilatory© Jones dead & Bartlett space volume Learning, (Vd) is estimated LLC at © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION T-1, and MR-1NOT ventilators. FOR SALE IntelliVent OR ASV DISTRIBUTION (Hamilton 2.2 mL/kg: S1 ventilator) provides a form of ASV that adds a

Vd = 2.2. mL/kg IBW × IBW (kg). closed-loop system to control oxygenation based on the ARDSNet PEEP tables and Spo to adjust Fio and PEEP.2 In this example for a 70 kg (IBW) patient the esti- 2 2 mated dead space volume would be: Airway Pressure-Release Ventilation © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Airway pressure-release ventilation (APRV) employs NOT FOR SALE ORVd DISTRIBUTION = 2.2 mL/kg × 70 kg = 154 mL. NOT FOR SALE OR DISTRIBUTION two levels of pressure, which are time triggered and

9781284139860_CH06_311_366.indd 344 20/02/19 5:00 PM Choice of Mode 345

Phigh

Time © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC T T NOT FOR SALE OR DISTRIBUTIONhigh low NOT FOR SALE OR DISTRIBUTION FIGURE 6-5 Airway Pressure-Release Ventilation.

© Jones & timeBartlett cycled. Learning, Patients may LLC breathe spontaneously at © JonesAPRV & Bartlettmay decrease Learning, peak airway LLC pressures, improve NOT FOR SALEboth levels OR not DISTRIBUTION unlike providing two levels of CPAP. TheNOT alveolar FOR SALErecruitment, OR improveDISTRIBUTION oxygenation, and increase high-pressure level may be set to last several seconds ventilation in dependent lung zones in patients with (e.g., 3 to 6 sec) to promote alveolar stabilization and ARDS (as compared to conventional ventilatory sup- alveolar recruitment in patients with severe hypoxemic port).26 Because spontaneous breathing is allowed dur- respiratory failure (e.g., ARDS). The ventilator then ing APRV, there may be some physiologic benefits (e.g., cycles to the low-pressure© Jones setting & for Bartlett a brief period Learning, LLCspontaneous breathing may promote© Jones recruitment & Bartlett of Learning, LLC (e.g., 0.5 to 0.8 sec) toNOT aid in FOR CO2 removal, SALE lowerOR DISTRIBUTION mean dependent alveoli, improve gasNOT exchange, FOR and SALE improve OR DISTRIBUTION airway pressures, and reduce the risk of cardiovascular cardiac filling). There is also some evidence that APRV compromise. Figure 6-5 illustrates high and low airway has the potential to decrease the need for sedation and pressures and times during APRV. administration of paralytic agents, decrease the time on Ventilator settings during APRV include high airway the ventilator, and reduce ICU length of stay as com- 26 pressure© Jones (Phigh), & high-pressure Bartlett Learning, time (Thigh), LLClow airway pared to conventional© Jones approaches. & Bartlett Like Learning, other forms LLC pressureNOT (PFORlow), and SALE low-pressure OR DISTRIBUTION time (Tlow). Phigh and of pressure-controlNOT FOR ventilation, SALE tidal OR volume DISTRIBUTION may vary Plow are the two levels of pressure provided and function during APRV with changes in the patient’s condition like two levels of CPAP in the presence of spontaneous and a minimum minute ventilation is not guaranteed. breathing. Thigh and Tlow represent the time periods set As with PC-IRV, short expiratory times can result in the for each pressure level. Plow and Tlow represent the air- development of autoPEEP and higher mean airway pres- © Jones & wayBartlett pressure-release Learning, level LLC and airway pressure-release © Jonessures can& Bartlett reduce venous Learning, return and LLC compromise cardiac time. APRV can be classified as a form of PC-IMV. In output in patients with hemodynamic compromise. NOT FOR SALEthe absence OR of DISTRIBUTION spontaneous breathing, however, APRV NOTAPRV FOR generally SALE isOR not DISTRIBUTION indicated for use in patients with functions as time-triggered pressure control-continuous severe obstructive lung disease due to the potential for mechanical ventilation (PC-CMV). As noted, Thigh air trapping and barotrauma. APRV has not been shown generally is > Tlow and in the absence of spontane- to improve mortality or other important outcomes as 2, 26 ous breathing, APRV© can Jones provide & pressure-controlled Bartlett Learning, LLCcompared to more conventional© Jonesmodes of & ventilation. Bartlett Learning, LLC inverse-ratio ventilation (PC-IRV). APRV is available as APRV (Dräger Evita XL, Evita Tidal volume (Vt)NOT provided FOR by theSALE ventilator OR duringDISTRIBUTION Infinity V500), Bi-level (CovidienNOT PB FOR 840 and SALE 980), OR DISTRIBUTION APRV is determined by the pressure gradient between BiVent and BiVent/APRV (Maquet Servo-i and Servo-u), the two pressure levels (ΔP = Phigh – Plow), the duration APRV and DuoPAP (Hamilton G-5 and C-3), and of high pressure (Thigh), and the patient’s pulmonary BiPhasic (Yvaire AVEA). mechanics (i.e., compliance and resistance). Put another © Jones & Bartlett Learning, LLC Proportional© JonesAssist Ventilation & Bartlett Learning, LLC way,NOT the transition FOR SALE from P ORlow to DISTRIBUTIONPhigh inflates the lungs NOT FOR SALE OR DISTRIBUTION while the transition from Phigh to Plow allows the lungs to Proportional assist ventilation (PAV) automatically ad- deflate. The patient’s alveolar ventilation and Paco2 are justs the level of ventilatory support based on estimated determined by the Vt, frequency of the airway pressure- WOB and feedback measures associated with the neural release maneuver, and level of the patient’s spontaneous output of the respiratory center.2 Specifically, the pa- © Jones & breathing.Bartlett For Learning, example, if LLCThigh is 4.2 seconds and Tlow is © Jonestient’s &spontaneous Bartlett inspiratoryLearning, effort LLC (as inspiratory gas NOT FOR SALE0.8 seconds, OR theDISTRIBUTION cycle time would be 5 seconds and pro-NOTflow) FOR reflects SALE the OR patient’s DISTRIBUTION respiratory drive. The ventila- vide 12 inspiratory/expiratory cycles per minute. tor calculates delivered volume and estimates resistance

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© Jones &and Bartlett compliance Learning, (as elastance) LLC by applying a brief © Jonesneeded & to Bartlett overcome Learning,the elastic and LLC resistive loads of the end-inspiratory pause and expiratory pause every few lung. This pressure may be provided by the ventilator or 2 NOT FOR SALE OR DISTRIBUTION NOT FOR SALEseconds. OR Inspiratory DISTRIBUTION pressure is varied automatically the respiratory muscles, or both. depending on the patient’s inspiratory effort, calculated P ventilator + P respiratory muscles = WOB, and the clinician-set percentage of support. In- elastance × volume + resistance × flow spiratory pressure and inspiratory time may vary breath 2 to breath and within© each Jones breath. & Bartlett Learning, LLCAs noted, the patient’s spontaneous© Jones inspiratory & Bartlett flow Learning, LLC Work is simply forceNOT times FOR distance; SALE WOB OR is DISTRIBUTIONa func- provides an estimate of the neuralNOT output FOR ofSALE the respira- OR DISTRIBUTION tion of pressure times volume (see Box 6-8). The level tory centers and inspiratory effort. Thus, PAV adjusts of support provided can be adjusted from 5% to 95% so the level of support based on the patient’s inspiratory that the WOB is in the range of approximately 0.5 to 1.0 effort and changing lung mechanics (i.e., compliance J/L.2 The ventilator monitors the patient’s inspiratory and resistance). Pressure may vary from breath to flow© andJones calculates & Bartlett the pressure Learning, required forLLC ventilation breath depending© Jones on changes & Bartlett in the patient’s Learning, pulmonary LLC basedNOT on theFOR equation SALE of motionOR DISTRIBUTION. Recall that the equa- mechanics andNOT inspiratory FOR SALE flow demand.OR DISTRIBUTION Breaths are tion of motion describes the pressure required to over- cycled to expiration by flow, similar to breath cycling come the elastic and resistive properties or loads of the with pressure-support ventilation; the flow termina- lung–thorax system. Recall also that compliance is the tion criterion is adjustable. Box 6-8 provides additional inverse of elastance and that work is required to over- information about WOB. Box 3-11 (Chapter 3) provides © Jones & comeBartlett these Learning,elastic and resistive LLC forces. The elastic forces© Jonesadditional & Bartlett information Learning, about the equationLLC of motion. NOT FOR SALEare proportional OR DISTRIBUTION to tidal volume and the resistive forcesNOT FORPAV maySALE improve OR patient–ventilatorDISTRIBUTION synchrony and are proportional to the airflow. patient comfort.2 PAV assumes intact neural control of The required WOB can be performed by the patient respiration and no leaks in the system (a system leak or the ventilator, or both may contribute to the total work can be misinterpreted as increased patient effort and in- necessary. Put another way, the equation of motion decreased inspiratory effort). A runaway phenomenon may scribes the elastic and© resistive Jones loads & Bartlett contributing Learning, to the LLCoccur, resulting in in excessive© volume Jones and & pressure Bartlett deliv Learning,- LLC WOB and predicts theNOT pressures FOR needed SALE to ORovercome DISTRIBUTION ery if the clinician has set the percentageNOT FOR of supportSALE tooOR DISTRIBUTION these workloads. The ventilator can perform some or all high; if the percentage of support is too low, WOB may be this work thus unloading the ventilatory muscles. In the excessive.2 It must also be noted that PAV does not pro- presence of ventilatory work provided by the ventilator vide an automatic minimal support level and alarms and and work provided by the respiratory muscles, the equa- backup ventilation modes must be activated in the event tion© of Jones motion can& Bartlett be simplified, Learning, where P is LLC the pressure of apnea or ©otherwise Jones absent & Bartlett or minimal Learning, patient effort. LLC It NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

BOX 6-8 Work of Breathing Work of breathing (WOB) is the work done by the kg × m or joules OR normalized to volume (i.e., © Jones & Bartlettventilatory Learning, muscles and/or LLC mechanical ventilator to © Jonesjoules/L) & Bartlett where: Learning, LLC NOT FOR SALEovercome OR elasticDISTRIBUTION and resistive forces opposing ventilaNOT- FOR SALE OR DISTRIBUTION 1 joule = 0.1 kg × m. tion. Work is force × distance and work units are kilograms × meters (kg × m) or joules (1 joule = 1 joule per liter = joule/L = 0.1 kg × m/L 0.1 kg m). Pressure is force per unit surface area (force/ × Normally work occurs during inspiration and surface area) while volume is distance cubed (m3 3 © Jones & Bartlett Learning, or cm ). LLCis performed by the diaphragm© Jones and accessory& Bartlett Learning, LLC WOB is a functionNOT of the FOR pressure SALE change OR × DISTRIBUTION volume muscles of inspiration; expirationNOT FOR is normally SALE OR DISTRIBUTION change (∆P × ∆V): passive requiring only the elastic recoil of the yyWork = force × distance. lung tissue (i.e., no work). With severe obstruc- yyPressure is force per unit surface area tive lung disease, the accessory muscles of ex- 2 © Jones(force/cm & Bartlett). Learning, LLC piration ©may Jones be engaged & Bartlett increasing Learning, WOB during LLC 2 2 NOTyySurface FOR areaSALE is distance OR DISTRIBUTION often reported as cm . exhalation.NOT FOR SALE OR DISTRIBUTION yyVolume may be recorded in cm3 (i.e., cc or mL). Normal WOB normalized to volume is about 0.5 to yyWOB = ∆P × ∆V = force/cm2 × cm3 1.0 joules per liter; > 1.5 joules/L may be an exces- = force × cm = force × distance. sive workload. Proportional assist ventilation (PAV) is typically set © Jones & BartlettWOB canLearning, be measured LLC as pressure units (cm © Jones & Bartlett Learning, LLC so WOB is 0.5 to 1.0 joules per liter. NOT FOR SALEH2 O)OR × volumeDISTRIBUTION units (L) and then converted to NOT FOR SALE OR DISTRIBUTION

9781284139860_CH06_311_366.indd 346 20/02/19 5:00 PM Choice of Mode 347

© Jones &must Bartlett also be Learning, noted that calculated LLC WOB may not reflect© JonesAs noted,& Bartlett automode Learning, can be set LLCto the alternate be- actual patient effort. For example, a patient may make a NOTtween FOR PRVC SALE and OR VS withDISTRIBUTION a target minute ventilation NOT FOR SALElarge effort OR that DISTRIBUTION results in little or no volume or flow. In based on the set tidal volume and respiratory rate. Used this case, while the patient effort is large, the calculated in this manner, the ventilator monitors the patient’s WOB will not reflect that effort because the volume tidal volume and automatically adjusts inspiratory pres- change is small. PAV is not useful in patients with a weak sure between breaths to achieve an average exhaled tidal ventilatory drive or weak© Jones respiratory & Bartlett muscles. Learning, LLCvolume at the set target. If the© spontaneous Jones & Bartlettrespiratory Learning, LLC PAV is available onNOT the CovidienFOR SALE PB 840 OR and DISTRIBUTION PB rate does not achieve the minimumNOT FORminute SALE ventilation OR DISTRIBUTION 980 as spontaneous proportional assist. The Dräger target, mandatory time-triggered breaths are provided. Evita V 500 offers spontaneous proportional pressure Inappropriate sensitivity settings, resulting in auto- support, which allows the clinician to set the amount triggering, can mislead the ventilator regarding the level of resistance to be supported as flow assist and the of spontaneous breathing present. As with other modes amount of elastance to be supported as volume as- of ventilation, attention to appropriate alarm settings is ©31 Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC sist.NOT The FOR Phillips SALE Respironics OR DISTRIBUTION V60 ventilator provides required. AutomodeNOT FOR is available SALE on OR the DISTRIBUTIONMaquet Servo-i a noninvasive form of PAV as proportional pressure and Servo-u. support, which may be useful in treating patients with Neurally Adjusted Ventilatory Assist (NAVA) sleep disorders. Proportional assist ventilation can be classified as NAVA incorporates an esophageal catheter with a mul- a form of pressure control-continuous spontaneous tiple array electrode to detect the electrical discharge © Jones & Bartlett Learning, LLC 4 © Jones & Bartlett Learning, LLC NOT FOR SALEventilation OR with DISTRIBUTION servo breath targeting (PC-CSVr). TheNOT from FOR the SALE diaphragm OR (Edi). DISTRIBUTION Edi provides a reflection proportional pressure-support mode available with the of the respiratory center’s neural output to the dia- Respironics V 60, however, would be best classified as a phragm.28 This diaphragmatic signal is used to trig- form of pressure control-intermittent mandatory venti- ger, adjust flow, and cycle the ventilator.2 Because the 4 lation (PV-IMVs,r). PAV has not yet been shown to sig- strength of the diaphragmatic signal varies throughout nificantly improve important clinical outcomes.2 inspiration, pressure will also vary throughout inspira- © Jones & Bartlett Learning, LLC28 © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONtion. NAVA may provide betterNOT coordination FOR SALE between OR DISTRIBUTION Automode the patient’s central respiratory drive and the ventilator’s inspiratory trigger, flow, and cycle. The degree Automode is a form of IMV that incorporates a target- of support provided varies with the amplitude of the ing scheme for both primary and secondary breaths diaphragmatic signal and assist level set by the respira- based on the modes selected. Automode uses IMV to tory care clinician.6 Tidal volume will vary from breath synchronize© Jones mandatory & Bartlett and spontaneousLearning, breathsLLC by au- © Jones & Bartlett Learning, LLC to breath in proportion to the patient’s inspiratory tomaticallyNOT FOR switching SALE between OR DISTRIBUTION two modes of ventilation NOT FOR SALE OR DISTRIBUTION 4 demand. NAVA can be classified as a form of pressure based on specific feedback measures. This allows the control-continuous spontaneous ventilation with servo ventilator to automatically titrate the level of support breath targeting (PC-CSVr), not unlike proportional as- provided between control and support modes depen- sist ventilation (PAV). dent on the patient’s level of spontaneous ventilation. Up to 25% of ventilator patients experience patient– © Jones & InBartlett the event Learning, of apnea, the LLC ventilator will automatically © Jones & Bartlett Learning, LLC ventilator asynchrony.33 Patient–ventilator asynchrony switch to a time-triggered control mode. Automode NOT FOR SALE OR DISTRIBUTION NOTmay FOR lead SALE to patient OR discomfort, DISTRIBUTION increased WOB, dia- may be especially useful in patients who have a vari- phragmatic dysfunction, the need for increased seda- able respiratory drive due to fatigue, pain, changing tion, and delayed liberation from the ventilator. NAVA lung mechanics, or intermittent apnea. Automode can was developed to provide spontaneously breathing be used to provide an automated form of ventilator patients greater control of their ventilatory pattern weaning. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC during mechanical ventilatory support.28 NAVA’s in- Automode can be set to titrate the level of ventilation NOT FOR SALE OR DISTRIBUTIONtent is to achieve neural-ventilatoryNOT FORcoupling, SALE which OR DISTRIBUTION provided between the following modes: should improve trigger synchrony and cycle synchrony. ■■ Volume control (VC) and volume support (VS). Neural–ventilatory coupling refers to the time between Used in this fashion, automode can be classified as the spontaneous breath and the delivery of a me- © JonesVC-IMV d,a& usingBartlett dual targetingLearning, for VC LLC and adap- chanical breath.© Jones Neural–ventilatory & Bartlett couplingLearning, is faster LLC tive targeting for VS. with NAVA than with conventional flow or pressure- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE26 OR DISTRIBUTION ■■ Pressure control (PC) and pressure support (PS). triggered ventilatory support. Another advantage of Used in this fashion, automode can be classified as NAVA is ventilator triggering should not be adversely PC-IMVs,s using set-point targeting for PC and PS. affected in patients with flow limitations and autoPEEP ■■ Pressure-regulated volume control (PRVC) and and this may be helpful in patients with COPD.2 © Jones & Bartlettvolume Learning, support (VS). LLC Used in this fashion, auto- © JonesAs described,& Bartlett the Learning, degree of support LLC provided with mode can be classified as PC-IMV using adap- NOT FOR SALE OR DISTRIBUTION a,a NOTNAVA FOR varies SALE with OR the DISTRIBUTION amplitude of the diaphragmatic tive targeting for both PRVC and VS. signal and the assist level set by the clinician. As the set

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© Jones &NAV BartlettA level Learning,is increased, theLLC inspiratory pressure pro- © Jonesfor patients & Bartlett who are Learning,heavily sedated LLC or have other CNS vided in proportion to the diaphragmatic signal also in- problems that depress spontaneous ventilation. NAVA 28 NOT FOR SALE OR DISTRIBUTION NOT FOR SALEcreases. OR Initially, DISTRIBUTION NAVA settings should be adjusted to does not provide a minimal support level and alarms produce the same or slightly lower inspiratory pressures and apnea backup ventilation modes must be employed. as the patient was receiving during conventional ventila- Also, as noted should apnea occur the ventilator will tion. Settings may then be adjusted until a comfortable automatically switch to time-triggered pressure control and consistent tidal volume© Jones is achieved & Bartlett while observingLearning, LLC(PC-CMV) as a safety feature.© The Jones respiratory & Bartlett care cli- Learning, LLC the diaphragmatic signal displayed on the ventilator nician can set the backup PC-CMV pressure, rate, and NOT FOR SALE OR DISTRIBUTION 28 NOT FOR SALE OR DISTRIBUTION screen. In general, as NAVA levels are increased, peak inspiratory time. pressure and tidal volume will increase, although this is NAVA has been safely used in adults, children, and dependent on patient effort and the strength of the dia- neonates and there is evidence that NAVA may improve phragmatic signal. patient–ventilator trigger and cycle synchrony and 2 The© Jones ventilator & Bartlettcan be set toLearning, cycle to expiration LLC when reduce the need© Jones for sedation. & Bartlett Patients Learning, may be more LLC theNOT diaphragmatic FOR SALE signal decreasesOR DISTRIBUTION to 40% to 70% of its comfortableNOT as NAVA FOR allows SALE them OR to determine DISTRIBUTION their maximum signal strength. Normally, the diaphragmatic own ventilatory pressures, volumes, and respiratory signal decreases as inspiratory effort decreases, and ex- rates.28 The level of support provided varies based on the piration begins. The goal is to avoid continued inflation patients’ respiratory drive. Outcomes data that NAVA when the patient’s central respiratory control centers improves important clinical outcomes such as liberation have switched to the expiratory phase. Cycling criteria from the ventilator or survival are not currently avail- © Jones & Bartlett Learning, LLC © Jones26 & Bartlett Learning, LLC NOT FOR SALEis normally OR set DISTRIBUTION at 70% of peak inspiratory diaphragmaticNOT able. FOR NAVA SALE is availableOR DISTRIBUTION on the Maquet Servo-i and activity. With inadequate levels of support, the patient Servo-u. may exhibit signs of distress with increased respiratory Recently an option to provide noninvasive ventila- rate; ventilatory muscle fatigue may ensue. If support tory support using NAVA has been developed and provided is greater than necessary, large tidal volumes newer Servo ventilators allow NAVA to be used to pro- 28 may result with suppression© Jones of the & diaphragmaticBartlett Learning, signal. LLCvide invasive or noninvasive ventilatory© Jones support. & Bartlett Learning, LLC Optimal NAVA supportNOT will FOR allow SALEthe patients OR toDISTRIBUTION com- NOT FOR SALE OR DISTRIBUTION fortably choose their respiratory rate and tidal volume and maintain adequate alveolar ventilation while un- RC Insight loading the respiratory muscles. Drawbacks of NAVA include the expense and inva- Newer modes of ventilation have been shown to sive© nature Jones of the & esophagealBartlett Learning, catheter, which LLC may cause be safe and© effective;Jones & however, Bartlett they Learning, do not signifi- LLC discomfort;NOT FOR catheter SALE displacement OR DISTRIBUTION and signal loss are cantly improveNOT importantFOR SALE patient OR outcomes. DISTRIBUTION other potential problems. Contraindications for the placement of an esophageal catheter precludes the use of NAVA. In the case of the loss of the catheter signal, High-Frequency Ventilation the ventilator will automatically switch to conventional, 28 © Jones & patient-triggeredBartlett Learning, pressure-support LLC mode. © JonesHigh-frequency & Bartlett ventilation Learning, (HFV) LLC employs very rapid Spontaneous breathing is required with NAVA, and respiratory rates (> 60 to 3000 breaths/min) and very NOT FOR SALEit should OR not DISTRIBUTIONbe used in patients who are heavily sedatedNOT small FOR tidal SALE volumes OR at DISTRIBUTION or below that of anatomic dead or otherwise have respiratory center depression. NAVA space volume. HFV has been used in neonatal, pediat- is also contraindicated in patients with spinal cord in- ric, and adult patients as a lung-protective strategy. Its jury, brain center damage, absent phrenic nerve activity, primary use in adults is as a rescue mode for patients neuromuscular transmission© Jones problems & Bartlett or blockade, Learning, LLCwith severe ARDS who have failed© Jones to respond & Bartlett to con- Learning, LLC or apnea.28 Should a patient become apneic during ventional ventilation using a lung-protective strategy. NAVA, the ventilatorNOT will automatically FOR SALE switch OR toDISTRIBUTION time- Routine use of HFV for patientsNOT withFOR ARDS SALE is not OR DISTRIBUTION triggered pressure control.28 NAVA also depends on supported by current evidence.2 HFV has been sug- adequate neurotransmission via the phrenic nerve to gested for several other conditions including broncho- the diaphragm and an intact vagal reflex.28 It should be pleural fistula, neonatal respiratory distress syndrome noted© Jones that lung & transplant Bartlett patients Learning, may not LLC have an in- (RDS), burns© withJones inhalational & Bartlett injury, Learning, and head trauma LLC tactNOT vagal FORreflex SALEand are ORnot candidates DISTRIBUTION for NAVA. with increasedNOT intracranial FOR SALE pressure OR (ICP). DISTRIBUTION HFV can As with any ventilatory mode, proper alarm settings successfully ventilate patients with large air leaks (e.g., are an important consideration. In addition to an au- tracheoesophageal fistula, bronchopleural fistula) and dible alarm for diaphragmatic signal loss (e.g., catheter may be helpful in cases of major airway disruption that displacement) or apnea, alarms are also available for cannot be successfully managed with conventional 28 © Jones & highBartlett pressure, Learning, PEEP, minute LLC ventilation, and rate. As © Jonesventilation. & Bartlett HFV has Learning, been used extensively LLC to support NOT FOR SALEnoted above, OR DISTRIBUTIONNAVA requires spontaneous breathing NOTneonates FOR SALE with RDS OR and DISTRIBUTION in those with pulmonary air with an intact ventilatory drive and is not appropriate leaks and bronchopulmonary dysplasia with generally

9781284139860_CH06_311_366.indd 348 20/02/19 5:00 PM Initial Ventilator Settings 349

2 © Jones &good Bartlett results. Learning, Currently there LLC are four major types of © Jonesprovides & Bartlettrelatively high Learning, mean alveolar LLC pressures with HFV available as described below. minimal fluctuation (as compared to conventional NOT FOR SALE OR DISTRIBUTION2 NOT FOR SALEHigh-frequency OR DISTRIBUTION positive-pressure ventilation (HFPPV) mechanical ventilation). This may help prevent cyclic as applied to adults uses tidal volumes in the range alveolar inflation—deflation (i.e., cyclic recruitment– of 100 to 200 mL with respiratory rates of 60 to 120 derecruitment), which may contribute to alveolar injury breaths/min. HFPPV can be accomplished using current in patients with ARDS. HFOV may also minimize alveo- 2 conventional ventilators© Jones and can & be Bartlett effective inLearning, ventilat- LLClar overdistention and help maintain© Jones alveolar & Bartlett patency. Learning, LLC ing patients with largeNOT air leaks. FOR HFPPV SALE is rarelyOR DISTRIBUTION used in HFOV has frequently beenNOT used inFOR preterm SALE neonates OR DISTRIBUTION the modern intensive care unit. in respiratory failure and may be useful as rescue ther- High-frequency percussive ventilation (HFPV) was apy when PIP ≥ 28 to 30 cm H2O or when mean airway 35 developed by Forrest Bird in the mid-1980s. HFPV incor- pressure > 10 cm H2O. In adults, HFOV is primarily porates a sliding Venturi device or Phasitron and com- used as a rescue mode for ARDS patients with refractory bines© high-frequencyJones & Bartlett oscillatory Learning, pulses (200 LLC to 900 beats hypoxemia that© Jones has failed & toBartlett respond toLearning, conventional LLC perNOT minute) FOR and smallSALE tidal OR volumes DISTRIBUTION with more trad- mechanical NOTventilation FOR using SALE a lung-protective OR DISTRIBUTION strategy. itional pressure-control ventilation. HFPV may improve HFOV is available for ventilation of neonates, in- oxygenation and ventilation and reduce the risk of baro- fants, and small children using the Vyaire 3100A. The trauma and hemodynamic compromise. HFPV may also Vyaire 3100B is designed to provide HFOV for adults be useful in promoting secretion clearance. HFPV has and larger children (> 35 kg). © Jones & beenBartlett advocated Learning, for ventilation LLC of burn patients with inha©- JonesIn summary,& Bartlett high-frequency Learning, ventilation LLC may be NOT FOR SALElational injuryOR DISTRIBUTION to maintain lower peak airway pressures, NOTprovided FOR SALE using high-frequency OR DISTRIBUTION positive-pressure venti- facilitate clearance of soot and secretions, and to facilitate lation (HFPPV), high-frequency percussive ventilation reinflation of collapsed alveoli.34 HFPV may reduce the (HFPV), high-frequency jet ventilation (HFJV), and incidence of pneumonia in patients with smoke inhala- high-frequency oscillatory ventilation (HFOV). HFOV tion and decrease ICP in patients with head injuries. has been the most commonly employed method to pro- HFPV is available ©for Jones critical-care & Bartlett applications Learning, as the LLCvide high-frequency ventilation© Jonesin neonates & Bartlettand adults. Learning, LLC Percussionaire VDR-4NOT volumetric FOR diffusiveSALE ORrespirator DISTRIBUTION HFV should be only employedNOT by FORskilled cliniciansSALE OR well DISTRIBUTION (Percussionaire Corporation). The Percussionaire IPV-1C familiar with its use. Management of ventilatory param- is primarily a therapy device to aid in secretion removal, eters with HFV can be complex. HFV may cause auto although it may be used in-line with other ventilators. PEEP due to reduced expiratory times and probably should High-frequency jet ventilation (HFJV) employs a jet be avoided in patients with obstructive lung disease. delivered through a special endotracheal tube adapter. HFV can be safe and effective in maintaining oxy- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,26 LLC HFJVNOT uses FOR constant SALE gas flow OR interruptersDISTRIBUTION that are time genation andNOT ventilation FOR inSALE various OR settings. DISTRIBUTION However, cycled and pressure limited.35 Tidal volume is depen- no form of HFV has been shown to be consistently su- dent on amplitude, jet driving pressure, jet orifice size, perior to conventional ventilation in reducing mortality length of inspiratory jet valve time on, and the patient’s or improving outcomes. Chapter 3 provides additional compliance and resistance. HFJV is used in conjunc- information regarding HFV. Chapter 11 describes the tion with a conventional ventilator, which can provide use of HFOV for adults with ARDS. © Jones & Bartlett Learning, LLC 35 © Jones & Bartlett Learning, LLC adjustable Fio2, PEEP, and 2 to 10 sigh breaths/min. NOT FOR SALEThe clinician OR DISTRIBUTION selects peak inspiratory pressure (PIP), jetNOT FOR SALE OR DISTRIBUTION frequency, and inspiratory jet valve time on.35 Initial Ventilator Settings HFJV is available with the Bunnell Life Pulse jet ven- Once the decision has been made to initiate mechanical tilator, which can deliver frequencies in the range of 240 ventilation, several important choices must be made. As to 660 cycles per minute.© Jones HFJV is& commonly Bartlett employed Learning, LLCnoted, mechanical ventilatory© support Jones can & be Bartlett invasive Learning, LLC in preterm neonates with RDS, although evidence that or noninvasive. Initiation of NIV was discussed earlier routine use of HFJV NOTimproves FOR patient SALE outcomes OR DISTRIBUTIONas com- in this chapter and additionalNOT information FOR isSALE provided OR DISTRIBUTION pared to conventional ventilation is lacking. in Chapter 10. Invasive mechanical ventilation requires High-frequency oscillatory ventilation (HFOV) uses establishment of an artificial airway, and mechanical very high frequencies in the range of 180 to 900 cycles/ ventilation is most commonly initiated following oral min© (3 Jones to 15 Hz; & 1Bartlett Hz = 60 cycles/min) Learning, and LLC very small endotracheal© intubation.Jones & Bartlett Learning, LLC tidalNOT volumes FOR (50 SALE to 250 mL).OR HFOVDISTRIBUTION is the most com- An appropriateNOT FOR ventilator SALE must OR be available DISTRIBUTION based monly used form of high-frequency ventilation in neo- on the patient’s needs and the expertise and experience nates and adults. HFOV creates a rapidly oscillating bias of the respiratory care clinician. The clinician must flow that affects gas transport through complex, incom- then choose the mode of ventilation and make import- pletely understood mechanisms.2 These mechanisms ant decisions about the tidal volume, respiratory rate, © Jones & mayBartlett include Learning, conventional LLC bulk flow, Taylor dispersion,© Jonesbreath & trigger, Bartlett inspiratory Learning, pressures, LLC flows, and time. pendeluft, asymmetric velocity profiles, cardiogenic The clinician must also choose an appropriate Fio2 and NOT FOR SALE OR DISTRIBUTION 27 NOT FOR SALE OR DISTRIBUTION mixing, and/or enhanced molecular diffusion. HFOV whether to implement PEEP or CPAP. Humidification,

9781284139860_CH06_311_366.indd 349 20/02/19 5:00 PM 350 CHAPTER 6 Ventilator Initiation

© Jones &alar Bartlettms, limits, Learning, and backup LLC apnea ventilation must then© JonesA third & Bartlett option sometimes Learning, appropriate LLC for initial be selected. Each of these choices is discussed below. NOTchoice FOR of SALE mode inOR spontaneously DISTRIBUTION breathing patients NOT FOR SALE OR DISTRIBUTION with an intact respiratory drive is PSV. Used as a pri- Mode mary standalone mode, PSV may be classified as pressure control-continuous spontaneous ventilation While there are several mode choices that may be ap- (PC-CSV). PSV generally is well tolerated by spontane- propriate in specific© situations, Jones &we Bartlettrecommend Learning, that the LLCously breathing patients and ©the Jones pressure & level Bartlett can be Learning, LLC initial mode for mostNOT adult FORand pediatric SALE patients OR DISTRIBUTION be adjusted to achieve a desired NOTtidal volume. FOR SALEPSV allows OR DISTRIBUTION volume control-continuous mandatory ventilation (VC- the patient to initiate and terminate each breath and it CMV) allowing for patient-triggered or time-triggered delivers a variable flow based on the patient’s inspira- ventilation. This mode is commonly referred to as tory effort. Thus, PSV may improve patient–ventilator assist-control volume ventilation. VC-CMV assures that synchrony and comfort while reducing the WOB. Two the patient will receive a minimum minute ventilation major drawbacks of PSV as a primary mode of ventila- ˙ © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC (Ve)NOT based FOR on the SALE set tidal OR volume DISTRIBUTION (Vt) and respiratory tion are present.NOT If FORapnea SALEor bradypnea OR DISTRIBUTIONoccur, there is rate (f). The set Vt is delivered consistently, even in the no backup ventilatory rate provided. Attention to venti- face of changes in the patient’s compliance or resistance. lator alarms and properly setting apnea backup ventila- Allowing for patient triggering enables the patient to set tion is very important. As with other forms of pressure his or her respiratory rate at a value above the minimum control, tidal volume will vary with changes in compli- set rate. In the event of apnea, sedation, or respiratory ance, resistance, or patient effort. © Jones & Bartlett Learning, LLC˙ © Jones & Bartlett Learning, LLC NOT FOR SALEcenter depression OR DISTRIBUTION Vt, f, and Ve are assured. VC-CMV NOT FORSIMV SALE is also aOR serviceable DISTRIBUTION option for initial ventilator also provides full ventilatory support and when properly setup and can be provided as volume control-intermittent applied may significantly reduce the WOB. mandatory ventilation (VC-IMV) or pressure control- The main disadvantages of VC-CMV are the variability intermittent mandatory ventilation (PC-IMV). SIMV, of PIP and Pplateau, introducing the possibility of inap- when properly applied, can provide full ventilatory propriately high pressures© Jones being delivered & Bartlett to the Learning, patient. LLCsupport, while allowing the patient© Jones to breathe & Bartlett sponta- Learning, LLC Patient triggering sometimesNOT FOR results SALE in an unacceptably OR DISTRIBUTION neously in between mandatoryNOT breaths. FOR Spontaneous SALE OR DISTRIBUTION high ventilatory rate resulting in a respiratory alkalosis, breaths can be pressure augmented using pressure especially in patients who are anxious or in pain. Inap- support or automatic tube compensation to reduce the propriately high triggering rates can also cause inadequate WOB associated with the artificial airway. While SIMV expiratory time resulting in air trapping and autoPEEP. has largely fallen out of favor in recent years, it can be VC-CMV© Jones is also & provided Bartlett using Learning, a fixed inspiratory LLC flow useful as an© alternative Jones for& Bartlettpatients with Learning, rapid spon- LLC rate,NOT which FOR can result SALE in an OR increased DISTRIBUTION WOB in spontane- taneous respiratoryNOT FOR rates SALEthat would OR otherwise DISTRIBUTION trigger ously breathing patients if the set inspiratory flow does the ventilator much too frequently when using a mode not meet or exceed the patient’s inspiratory demand. in which every patient trigger results in a mandatory Improper ventilator settings can also lead to patient– breath. It is used by some clinicians in patients with ventilator asynchrony. That said, VC-CMV generally is the status asthmaticus to limit the minute ventilation to © Jones & bestBartlett initial choice Learning, for most LLC critically ill adult patients. © Jonesaround & 10 Bartlett L/min and Learning, minimize air LLC trapping. An acceptable alternative to VC-CMV for initial Following initiation of mechanical ventilation and NOT FOR SALEmode choice OR isDISTRIBUTION PC-CMV set to allow patient-triggered orNOT patient FOR stabilizationSALE OR using DISTRIBUTION one of the above modes, the time-triggered breath initiation. This mode is commonly respiratory care clinician must thoroughly assess the referred to as assist-control pressure-control ventilation patient. It may then become apparent that an alternative (PCV). With PC-CMV, inspiratory pressure will not ex- mode should be considered. ceed the set pressure-control© Jones level, & thus Bartlett assuring Learning, that PIP LLC © Jones & Bartlett Learning, LLC and P remain in a safe range, despite changes in the Tidal Volume and Rate plateau NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION patient’s respiratory mechanics. PC-CMV also incorpo- Tidal volume, respiratory rate, and minute ventilation rates a variable inspiratory flow, which may be more com- determine the effectiveness of the ventilatory support fortable and better tolerated by some patients. The major provided. Each of these parameters may be set directly disadvantage of PC-CMV is that delivered Vt will vary or indirectly as described below. with© changesJones in & the Bartlett patient’s compliance, Learning, resistance, LLC or © Jones & Bartlett Learning, LLC inspiratoryNOT FOR effort. SALE Adjustment OR DISTRIBUTIONof PC-CMV to ensure tidal Normal TidalNOT Volume, FOR Rate,SALE and OR Minute DISTRIBUTION Ventilation volume delivery also requires that the respiratory care cli- A normal adult’s resting spontaneous tidal volume (Vt) nician fully understand the interactions between inspira- is about 5 to 7 mL/kg of ideal body weight (IBW) or tory pressure, inspiratory time, respiratory mechanics, and about 400 to 700 mL with a respiratory rate (f) in the patient effort. If apnea is present, PC-CMV will provide range of 12 to 18 breaths/min. Minute ventilation (V˙e) time-triggered ventilation (aka controlled ventilation). © Jones & Bartlett Learning, LLC © Jonesis simply & Bartletttidal volume Learning, (Vt) × rate LLC (f): Volume-targeted forms of PC-CMV (e.g., PRVC) provide NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION˙ good options for clinicians familiar with these modes. Ve = Vt × f

9781284139860_CH06_311_366.indd 350 20/02/19 5:00 PM Initial Ventilator Settings 351

© Jones & BartlettAssuming Learning, a normal adult LLC tidal volume (500 mL) and© Jonesacceptable & Bartlett tidal volume, Learning, usually in LLC the range of 4 to 8 respiratory rate (12 breaths/min), minute ventilation NOTmL/kg FOR IBWSALE and ORresulting DISTRIBUTION in a patient-triggered respira- NOT FOR SALEwould be: OR DISTRIBUTION tory rate of ≤ 25 breaths/min. Typically, this requires PSV levels of ≤ 20 cm H O (above PEEP). Recall that V˙e = Vt × f = 500 mL × 12 breaths/min = 2 with PSV all breaths are patient triggered and no time- 6000 mL/min or 6 L/min. triggered rate is set. In the event of apnea, an automatic ˙ The normal range (for© Jonesadults) for & eBartlettV is 5 to 10 Learning,L/min or LLCbackup apnea ventilation function© Jones should & be Bartlett set, as well Learning, LLC about 100 mL/kg IBW.NOT Note FOR that thereSALE are ORseveral DISTRIBUTION for- as setting other appropriate alarmsNOT andFOR limits. SALE OR DISTRIBUTION mulas for estimating IBW (e.g., Broca formula, Devine With VC-IMV and PC-IMV, mandatory breath tidal formula, and Hamwi formula). We use the formulas volume, pressure, and rate are set in a similar fashion as vol- suggested by ARDSNet, which are based on the Devine ume control- and pressure control-continuous mandatory formula for IBW calculation: ventilation (VC-CMV and P-CMV) as described above. © Jones & =Bartlett+ Learning, LLC © Jones & Bartlett Learning, LLC Males: IBW 50 2.3 (height in inches – 60) Inspiratory Pressure NOT FOR SALE= +OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Females: IBW 45.5 2.3 (height in inches – 60) High inspiratory pressures are associated with baro- Note: ARDSNet uses the term predicted body weight or trauma and lung injury. In general, Pplateau ≤ 28 to 30 cm PBW instead of IBW; the terms can be used interchange- H2O is thought to reduce the likelihood of ventilator- ably. Table 6-3 illustrates the calculation of tidal volume induced lung injury and lower plateau pressures are © Jones & andBartlett minute Learning,ventilation based LLC on ideal body weight. © Jonesassociated & Bartlett with better Learning, patient outcomes. LLC It should be NOT FOR SALE OR DISTRIBUTION NOTnoted, FOR however, SALE thatOR patientsDISTRIBUTION with decreased thoracic Initial Ventilator Settings for Tidal Volume and Rate compliance (e.g., chest wall deformity, obesity, and as- cites) may tolerate Pplateau > 28 to 30 cm H2O without With VC-CMV using set-point breath targeting (aka causing alveolar overdistention. assist-control volume ventilation) the clinician sets the With VC-CMV, peak inspiratory pressure (PIP) and desired Vt and f. For ventilator initiation in the VC-CMV © Jones & Bartlett Learning, LLCplateau pressure (Pplateau) will vary© Jones with changes & Bartlett in pa- Learning, LLC mode, we suggest an NOTinitial tidalFOR volume SALE of 8OR mL/kg DISTRIBUTION IBW tients’ compliance and resistance.NOT In FORgeneral, SALE PIP should OR DISTRIBUTION with a rate of 12 to 16 breaths/min for most patients. be ≤ 40 cm H2O while maintaining Pplateau ≤ 28 to 30 cm Tidal volume should be then adjusted (if necessary) to ≤ H2O. Ventilator adjustments that may reduce PIP during maintain a Pplateau 28 to 30 cm H2O. Slightly larger tidal volume ventilation include lowering the set tidal volume, volumes (e.g., 8 to 10 mL/kg) may be acceptable if P plateau decreasing the inspiratory peak flow, and changing the ≤ 28 to 30 cm H O.3 ARDS patients may require smaller © Jones &2 Bartlett Learning, LLC inspiratory flow© Jones waveform & Bartlett from a square Learning, wave to a LLCdown tidal volumes (e.g., 6 mL/kg IBW or less) to maintain NOT≤ FOR SALE OR DISTRIBUTION ramp. PplateauNOT can be FOR reduced SALE by lowering OR DISTRIBUTION the set tidal. Pplateau 28 to 30 cm H2O. Patients with neuromuscular With PC-CMV, PC-CSV, and PC-IMV the pressure- diseases may require larger tidal volumes to prevent atel- control level is set by the clinician to achieve an accept- ectasis. The spontaneously breathing patient may trigger able Vt while maintaining Pplateau ≤ 28 to 30 cm H2O. the ventilator at a rate greater than the set minimum rate. If smaller tidal volumes are required to maintain P ≤ © Jones & Bartlett Learning, LLC plateau © JonesIntermittent & Bartlett Sigh Breaths Learning, LLC 28 to 30 cm H2O (e.g., ARDS, severe pneumonia), higher NOT FOR SALEinitial respiratory OR DISTRIBUTION rates may be required. NOTNormal FOR SALEspontaneously OR DISTRIBUTION breathing subjects take an in- For PC-CMV using set-point breath targeting (aka termittent deep breath or sigh every 6 to 10 minutes. assist-control pressure-control ventilation [PCV]) we Monotonous shallow tidal breathing (< 7 mL/kg IBW) suggest an initial pressure-control setting of 12 to 15 without an intermittent deep breath may cause progres- cm H2O (above PEEP)© followedJones by& immediateBartlett observaLearning,- LLCsive atelectasis, and intermittent© deepJones breaths & Bartlett (sighs) will Learning, LLC tion of the resultant tidal volume. The pressure-control reverse this trend. Often modern critical care ventilators level is then quickly adjustedNOT FOR up or SALE down to OR achieve DISTRIBUTION incorporate a sigh function, whichNOT may FOR be set SALE by the cliniOR- DISTRIBUTION the desired Vt while ensuring Pplateau ≤ 28 to 30 cm cian to deliver an intermittent deep breath or sigh volume H2O. Initial rate is set in the range of 12 to 16 breaths/ at a specific interval. Traditionally, sigh breaths were set at min. Spontaneously breathing patients may trigger the 1.5 to 2 times the tidal volume to be delivered every 6 to ventilator© Jones at a rate& Bartlett greater than Learning, the set minimum LLC rate. If 10 minutes.© We Jones suggest &that Bartlett almost all Learning, patients receive LLC a ≤ smallerNOT tidal FOR volumes SALE are ORrequired DISTRIBUTION to maintain Pplateau minimal levelNOT of PEEP FOR (e.g., SALE 5 to 8 cmOR H 2DISTRIBUTIONO), which should 28 to 30 cm H2O to prevent alveolar overdistention (e.g., make institution of intermittent sigh breaths unnecessary. ARDS), higher initial respiratory rates may be required. That said, recruitment maneuvers are sometimes used For PC-CSV using set-point breath targeting (aka in patients with ARDS and function somewhat like an standalone pressure-support ventilation [PSV]), we sug- intermittent sigh. There is also some evidence that the use gest an initial PSV setting of 12 to 15 cm H2O (above of intermittent sighs may improve alveolar recruitment in © Jones & Bartlett Learning, LLC © Jones &2 Bartlett Learning, LLC NOT FOR SALEPEEP) followed OR DISTRIBUTION by immediate observation of the resul-NOTARDS. FOR ChaptersSALE OR 7 and DISTRIBUTION 8 provide additional discussion of tant tidal volume. PSV is then adjusted to achieve an the use of recruitment maneuvers in ARDS.

9781284139860_CH06_311_366.indd 351 20/02/19 8:26 PM 352 CHAPTER 6 Ventilator Initiation

© Jones & BartlettTABLE 6-3 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALETidal Volume OR DISTRIBUTION and Minute Ventilation Based on Ideal BodyNOT Weight FOR SALE OR DISTRIBUTION Males Tidal volume (Vt) V˙ e

Height (in) IBW (kg) 4 mL/kg 6 mL/kg 8 mL/kg 10 mL/kg 100 mL/kg

60 50 200 300 400 500 5000 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 61 52.3NOT FOR SALE209.2 OR DISTRIBUTION313.8 418.4 523 NOT FOR5230 SALE OR DISTRIBUTION 62 54.6 218.4 327.6 436.8 546 5460

63 56.9 227.6 341.4 455.2 569 5690

64 59.2 236.8 355.2 473.6 592 5920 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 65NOT FOR SALE61.5 OR DISTRIBUTION246 369 492 NOT FOR615 SALE OR DISTRIBUTION6150 66 63.8 255.2 382.8 510.4 638 6380

67 66.1 264.4 396.6 528.8 661 6610

68 68.4 273.6 410.4 547.2 684 6840 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE69 OR DISTRIBUTION70.7 282.8 424.2NOT FOR 565.6SALE OR DISTRIBUTION707 7070 70 73 292 438 584 730 7300

71 75.3 301.2 451.8 602.4 753 7530

72 77.6 310.4 465.6 620.8 776 7760 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 73 79.9 319.6 479.4 639.2 799 7990 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 74 82.2 328.8 493.2 657.6 822 8220

Females Tidal volume (Vt) V˙ e

Height (in) IBW (kg) 4 mL/kg 6 mL/kg 8 mL/kg 10 mL/kg 100 mL/kg © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 60 45.5 182 273 364 455 4550 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 61 47.8 191.2 286.8 382.4 478 4780

62 50.1 200.4 300.6 400.8 501 5010

63 52.4 209.6 314.4 419.2 524 5240

NOT FOR SALE65 OR DISTRIBUTION57 228 342NOT FOR 456SALE OR DISTRIBUTION570 5700

66 59.3 237.2 355.8 474.4 593 5930

67 61.6 246.4 369.6 492.8 616 6160

68 63.9© Jones & 255.6Bartlett Learning,383.4 LLC 511.2 639 © Jones &6390 Bartlett Learning, LLC

69 66.2NOT FOR SALE264.8 OR DISTRIBUTION397.2 529.6 662 NOT FOR6620 SALE OR DISTRIBUTION

70 68.5 274 411 548 685 6850

71 70.8 283.2 424.8 566.4 708 7080

72© Jones & Bartlett73.1 Learning,292.4 LLC 438.6 584.8© Jones &731 Bartlett Learning,7310 LLC

73NOT FOR SALE75.4 OR DISTRIBUTION301.6 452.4 603.2NOT FOR 754SALE OR DISTRIBUTION7540

74 77.7 310.8 466.2 621.6 777 7770

Males: IBW = 50 + 2.3 (height in inches – 60). Females: IBW = 45.5 + 2.3 (height in inches – 60). © Jones & BartlettNote: ARDSNet Learning, uses the term predicted LLC body weight or PBW instead of IBW;© the Jones terms can be& used Bartlett interchangeably. Learning, Set ventilator tidalLLC volumes may be rounded, NOT FOR SALEas appropriate. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284139860_CH06_311_366.indd 352 20/02/19 5:00 PM Initial Ventilator Settings 353

© Jones &Breath Bartlett Trigger Learning, LLC © Jonesalso sets & eitherBartlett the peak Learning, flow and LLCflow waveform or the inspiratory time and flow waveform. For assist-control NOT FOR SALEPatient-triggered OR DISTRIBUTION breaths may be (negative) pressure or NOT FOR SALE OR DISTRIBUTION flow triggered. With pressure triggering, a patient inspira- ventilation, the clinician also sets trigger sensitivity. tory effort decreases the ventilator circuit pressure to a In ventilators with a peak flow control, peak flow, flow clinician-selected level, thus triggering inspiration. With waveform, and tidal volume determine inspiratory time. flow triggering, a constant flow of gas during the expira- As peak flow increases, inspiratory time decreases and tory phase is disrupted© byJones the patient’s & Bartlett inspiratory Learning, effort, LLCvice versa. In ventilators with© an Jones inspiratory & Bartlett time set- Learning, LLC triggering inspiration.NOT In either FOR case, SALE the trigger OR sensitivity DISTRIBUTION ting, inspiratory time, tidal volume,NOT FORand flow SALE waveform OR DISTRIBUTION should be adjusted to minimize trigger work while avoid- determine peak flow. Inspiratory time is set directly in ing autotriggering. For pressure triggering, the trigger these ventilators and inspiratory flow varies to ensure tidal volume delivery within the set inspiratory time. generally is set between –0.5 and –1.5 cm H2O, although some circuits may require trigger sensitivity be set at –2.0 Many ventilators allow the clinician to choose be- 2,27 tween a square wave (constant flow) flow waveform and cm© H 2JonesO to avoid & autotriggering. Bartlett Learning, With flow LLC triggering © Jones & Bartlett Learning, LLC theNOT trigger FOR sensitivity SALE generally OR isDISTRIBUTION set at the range of 1 to a down rampNOT (decreasing FOR SALEflow waveform). OR DISTRIBUTION In ventilators 2 L/min below the baseline or bias flow, although some with peak flow controls, a square wave will result in a systems may require flow triggers as high as 3 to 4 L/min shorter inspiratory time, higher PIP, and lower mean below baseline or bias flow to avoid autotriggering.2,27 airway pressure (as compared to a down ramp). In ven- Inappropriate trigger sensitivity settings and autoPEEP tilators with peak flow controls, a down-ramp waveform © Jones & canBartlett increase Learning, trigger work. LLCTrigger asynchrony occurs © Joneswill result & Bartlett in a longer Learning, inspiratory time,LLC lower PIP, and NOT FOR SALEwhen the OR patient’s DISTRIBUTION inspiratory effort becomes decoupledNOT higher FOR mean SALE airway OR pressure DISTRIBUTION (as compared to a square from the ventilator trigger. With the current generation of wave). Ventilators with inspiratory time controls will critical care ventilators there are no clinically important vary the inspiratory flow based on the set tidal volume differences between a pressure and flow trigger.2,27 NAVA and inspiratory time. Changes in flow waveform in may also improve patient–trigger synchrony. these ventilators will affect PIP and mean airway pres- © Jones & Bartlett Learning, LLCsure. In general, flow waveforms© Jones that increase & Bartlett mean air- Learning, LLC NOT FOR SALE OR DISTRIBUTIONway pressure will tend to decreaseNOT PIP FOR and SALEvice versa. OR DISTRIBUTION RC Insight For VC-CMV, inspiratory time and respiratory rate determine the expiratory time and I:E ratio. In general, Patient-trigger sensitivity should be adjusted to an I:E ratio of 1:2 or lower is preferred. For VC-IMV, minimize trigger work without autocycling. mandatory and spontaneous breaths are interspersed © Jones & Bartlett Learning, LLC allowing the© patient Jones to initiate& Bartlett a spontaneous Learning, inspira- LLC NOT FOR SALE OR DISTRIBUTION tion followingNOT a mandatory FOR SALE breath. OR Thus, DISTRIBUTION the patient Inspiratory Phase, Expiratory Phase, and I:E Ratio has control of his or her spontaneous inspiratory time, spontaneous expiratory time, and spontaneous I:E ratio. Various ventilator controls will effect inspiratory time, We suggest an initial mandatory breath peak flow expiratory time, and I:E ratio, and these effects vary setting for VC-CMV and VC-IMV of 60 L/min with a depending on the mode of ventilation employed. Initial 27 © Jones & Bartlett Learning, LLC © Jonesrange of& 40Bartlett to 80 L/min Learning, for adult patients.LLC In ventila- ventilator settings are discussed further below. tors with an inspiratory time setting, we suggest an ini- NOT FOR SALE OR DISTRIBUTION NOTtial FOR inspiratory SALE time OR of DISTRIBUTION 0.8 seconds with a range of 0.6 to Volume Control 27 1.0 seconds for adult patients, although many patients With VC-CMV and VC-IMV using set-point breath do well with a slightly longer TI (e.g., 0.8 to 1.2 seconds). targeting (aka assist-control volume ventilation and We also suggest using a down-ramp flow waveform for volume SIMV), the clinician© Jones sets & the Bartlett desired Vt Learning, and f LLCinitial ventilator setup. This ©may Jones later be &adjusted Bartlett based Learning, LLC for mandatory breaths. With these modes, the clinician on patient assessment results. Box 6-9 summarizes NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

BOX 6-9 Initial Ventilator Settings for Assist-Control Volume Ventilation (VC-CMV) Initial ventilator settings for most adults receiving volume ventilation in the assist-control mode are summarized© Jones as follows. & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Ventilator Control Initial Setting

t Tidal volume (V ) 8 mL/kg IBW (range 6 to 8 mL/kg); adjust to ensure Pplateau ≤ 28 to 30 cm H2O. ARDS patients may require smaller tidal volumes to maintain Pplateau ≤ 28 to 30 cm H2O. Some patients with neuromuscular disease may require larger tidal volume. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Rate For assist-control (patient- or time-triggered ventilation), set the rate in the range of 12 to 14 breaths/min. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

(Continues)

9781284139860_CH06_311_366.indd 353 20/02/19 5:00 PM 354 CHAPTER 6 Ventilator Initiation

© Jones & Bartlett Learning, LLC © Jones & BartlettBOX 6-9 Learning, Initial Ventilator LLC Settings for Assist-Control Volume Ventilation (VC-CMV) NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (Continued)

Peak flow or For ventilators with peak flow control begin at 60 L/min (range 40 to 80 L/min). Adjust peak flow to ensure inspiratory time inspiratory flow meets or exceeds patient inspiratory demand. For ventilators withinspiratory time control, begin ©with Jones an inspiratory & Bartlett time setting ofLearning, 0.8 sec (range LLC 0.6 to 1.0 sec). Adjust inspiratory time© Jonesto ensure resultant & Bartlett flows Learning, LLC meet or exceed patient demand and avoid patient–ventilator asynchrony. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Trigger sensitivity Set pressure trigger –0.05 to –1.5 cm H2O. For flow, trigger set sensitivity at 1 to 2 L/min below baseline flow. Adjust trigger sensitivity to minimize trigger work without autocycling.

Flow waveform Begin with a decreasing flow waveform (down ramp). A decreasing flow waveform will reduce PIP and increase inspiratory time (in ventilators with a peak flow control) and mean airway pressure and may improve distribution of © Jones & Bartlettinspired gases. Learning, Consider square LLC wave to decrease inspiratory time© andJones decrease & meanBartlett airway pressures.Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Fio2 (O2 Begin with 100% O2 for patients in obvious distress or conditions that may require high initial O2 concentrations percentage) (e.g., multiple trauma, severe pneumonia, ARDS, carbon monoxide poisoning, pulmonary edema, and post- resuscitation cardiac arrest). If recent arterial blood gases and the patient’s condition (e.g., COPD) suggest

that 100% O2 will not be necessary, you may begin with a moderate to high Fio2 (e.g., 0.40 to 0.70.) Careful assessment and monitoring (including continuous Spo2) should guide appropriate adjustment in Fio2 to obtain © Jones & Bartlett Learning,adequate LLC arterial oxygenation at a safe oxygen© Jones concentration. & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION PEEP Initial PEEP setting for most patients is 5 cm H2O.

Humidification For heated humidification, adjust to obtain a temperature at the proximal airway of 35° to 37°C. A heat moisture exchanger may suffice for some patients.

Alarms and limits ©Set Jones appropriate & volume Bartlett and pressure Learning, alarms and LLC limits to ensure safe and effective ventilation© Jones (see Table& Bartlett 6-4) Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

TABLE 6-4 Initial Ventilator Alarm Settings for Adult Patients* Alarm© Jones & Bartlett Learning,Initial setting LLC © JonesAdjusted &value Bartlett Learning, LLC

Low-pressureNOT FOR limit SALE OR DISTRIBUTION8 cm H2O NOT5 to FOR 10 cm HSALE2O below ORPIP DISTRIBUTION

High-pressure limit 40 cm H2O 10 cm H2O above PIP; avoid PIP exceeding 40 cm H2O

Low PEEP/CPAP 3 to 5 cm H2O below initial PEEP setting to begin 2 cm H2O below PEEP/CPAP © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALELow Vt OR DISTRIBUTION100 mL below set Vt NOT FOR SALE100 OR mL DISTRIBUTIONbelow actual Vt

Low V˙ e 1 to 2 L/min below set V˙ e 1 to 2 L/min < actual V˙ e

High V˙ e 5 L/min or 50% above set V˙ e 5 L/min or 50% above actual V˙ e

Apnea backup ventilationNOT FORSet SALE Vt and f ORfor full DISTRIBUTION ventilatory support in the Set Vt and f for fullNOT ventilatory FOR support SALE in the OR DISTRIBUTION event of apnea event of apnea

High oxygen percentage 5% > set O2% 5% > actual O2%

Low oxygen percentage © Jones & Bartlett Learning,5% < set O 2LLC% © Jones5% < actual & OBartlett2% Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Humidifier temperature 35° to 37°C 35° to 37°C

Low humidifier temperature alarm 2°C below set temperature 2°C < actual temperature

High humidifier temperature alarm 1°C above set temperature 1°C above set temperature; do not exceed © Jones & Bartlett Learning, LLC © Jones & Bartlettdelivered Learning, temperature >LLC 37°C NOT FOR SALE*The initial OR alarm DISTRIBUTION settings should be set prior to patient connection to the ventilator.NOT Ventilator FOR alarms SALE and limits ORshould DISTRIBUTIONthen be adjusted based on the patient’s response. Data from Hyzy RC. Modes of mechanical ventilation. In: Parsons PE, Finlay G (eds.) UpToDate; October 2018.

9781284139860_CH06_311_366.indd 354 26/02/19 12:27 PM Initial Ventilator Settings 355

© Jones &initial Bartlett ventilator Learning, settings forLLC most adult patients when © Jonestime will & Bartlettdecrease and Learning, I:E ratio will LLC increase. With PC- using assist-control volume ventilation (aka patient- or NOTIMV, FOR the SALE patient ORmay DISTRIBUTIONintersperse spontaneous breaths NOT FOR SALEtime-triggered OR DISTRIBUTION VC-CMV). Clinical Focus 6-2 provides with mandatory breaths. In such cases, the patient will an example using VC-CMV. have control over his or her spontaneous inspiratory time, spontaneous expiratory time, and spontaneous I:E Pressure Control ratio. Box 6-10 summarizes initial ventilator settings for With PC-CMV and PC-IMV© Jones using & Bartlettset-point breath Learning, LLCmost adult patients when using© Jonesassist-control & Bartlett pressure- Learning, LLC targeting (aka assist-controlNOT FOR pressure-control SALE OR ventila- DISTRIBUTIONcontrol ventilation (aka patient-NOT or time-triggeredFOR SALE OR DISTRIBUTION tion [PCV] and pressure-control SIMV) the clinician PC-CMV). Clinical Focus 6-3 provides an example of a sets the inspiratory pressure, inspiratory time, and rate ventilator initiation using PC-CMV. (f) for mandatory breaths. With these two modes, the With PSV (aka PC-CSV), when used as a primary inspiratory pressure waveform is a square wave while mode of ventilation, the clinician sets the inspiratory the© inspiratory Jones &flow Bartlett waveform Learning, is a decreasing LLC flow that pressure-support© Jones level to& achieve Bartlett a desired Learning, tidal volume. LLC variesNOT with FOR the patient’s SALE inspiratory OR DISTRIBUTION effort. As noted The patientNOT triggers FOR and SALEcycles each OR breath DISTRIBUTION and thus above, inspiratory pressure is set to achieve the desired controls his or her inspiratory time, expiratory time, I:E tidal volume while maintaining Pplateau ≤ 28 to 30 cm ratio, and rate. H2O. The inspiratory time setting and rate determine the expiratory time and I:E ratio. Inspiratory time may RC Insight © Jones & beBartlett set initially Learning, in the range LLC of 0.6 to 1.0 seconds. For ex-© Jones & Bartlett Learning, LLC NOT FOR SALEample, withOR an DISTRIBUTION inspiratory time of 1.0 second and respi-NOT FORPressure-control SALE OR ventilation DISTRIBUTION is a good option for ratory rate of 15 breaths per min, the respiratory cycle patients with ARDS to maintain safe airway pres- = time will be 4 sec (60/15 4 sec); expiratory time will sures, while providing effective ventilation. be 3 sec resulting in an I:E ratio of 1:3. Pressure-control inverse-ratio ventilation (PC-IRV) may begin with an Pressure Rise Time or Slope I:E ratio 1:1 and increase© Jones the I:E ratio& Bartlett based on Learning, patient LLC © Jones & Bartlett Learning, LLC response. We suggestNOT that moreFOR conventional SALE OR modes DISTRIBUTION of Most modern ventilators allowNOT for adjustment FOR SALE of rise OR DISTRIBUTION lung-protective ventilation with appropriate levels of time (aka pressure slope) and expiratory sensitivity during PEEP be applied before attempting PC-IRV. PSV and these adjustments will alter the inspiratory pres- With PC-CMV, the patient may trigger the ventilator sure and flow waveforms. The inspiratory pressure rise more frequently than the set rate. In such cases, the in- time control adjusts the rate at which gas flow increases spiratory© Jones time will& Bartlett remain constant, Learning, while theLLC expiratory during inspiration.© Jones Normally, & Bartlett the rise timeLearning, is adjusted LLC so NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION CLINICAL FOCUS 6-2 Initiating Assist-Control Volume Ventilation (aka VC-CMV) A 50-year-old man presented to the emergency de- Question 1: What initial mode of ventilation is partment complaining of shortness of breath, cough, appropriate for this patient? © Jones & Bartlettyellow-colored Learning, sputum, LLC and fever with chills for © JonesAssist-control & Bartlett volume Learning, ventilation (aka LLC VC-CMV) to NOT FOR SALE2 weeks. OR The DISTRIBUTION patient was extremely short of breath andNOT provide FOR full SALE ventilatory OR DISTRIBUTIONsupport is a good initial choice on examination, the respiratory care clinician noted re- for most patients. Assist-control pressure-control ven- spiratory accessory muscle use, diaphoresis, and course tilation (PC-CMV) or volume control-SIMV (VC-SIMV) crackles upon auscultation. Vital signs were heart rate could also be used to provide full ventilatory support of 126, respirations of 35, blood pressure 160/92 mmHg, for this patient. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Spo2 84% (while breathing room air), and oral tempera- With assist-control volume ventilation, Question 2: ture of 102° F. ChestNOT radiographs FOR demonstratedSALE OR DISTRIBUTION bilateral what are appropriate choicesNOT for initial FOR tidal SALE OR DISTRIBUTION infiltrates. Arterial blood gas was obtained after the volume (Vt) and respiratory rate (f)? patient was placed on a nasal cannula at 5 L/min: Initial tidal volume should be 8 mL/kg IBW (range 6 to pH: 7.24 8 mL/kg) with a respiratory rate of 12 to 14 breaths/ © Jones & Bartlett Learning, LLC min. A rate in© theJones range &of 8Bartlett to 12/min Learning, may be neces- LLC Paco2: 68 mmHg NOT FOR SALE OR DISTRIBUTION sary to ensureNOT adequate FOR expiratory SALE OR time. DISTRIBUTION Ideal body Pao2: 48 mmHg weight can be estimated based on the patient’s height Sao : 0.83 2 using the following formula for males: - HCO3: 27 mEq/L IBW = 50 + 2.3 (height in inches – 60) NIV was considered; however, the decision was made © Jones & Bartlettto initiate Learning, invasive mechanical LLC ventilatory support. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (Continues)

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© Jones & Bartlett Learning, LLC © Jones & BartlettCLINICAL Learning, FOCUS 6- LLC2 Initiating Assist-Control Volume Ventilation (aka VC-CMV) (Continued) NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION If this patient is 5 ft 10 in tall (70 in) his estimated IBW Desired V˙ e = IBW × 100 mL/kg/min = 73 kg × would be: 100 mL/kg/min = 7300 mL/min (7.3 L/min). IBW = 50 + 2.3 (70 – 60) = 73 kg (or 168 lb). Given a tidal volume of 584 mL, the rate needed to Vt (desired) will© beJones 8 mL/kg & ×Bartlett 73 kg = 584 Learning, mL. LLCachieve this minute ventilation© would Jones be: & Bartlett Learning, LLC f = V˙ e ÷ Vt = 7300 mL ÷ 584 mL = 12.5 breaths/min. Question 3. What’sNOT an appropriate FOR SALE initial OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION respiratory rate for this patient? The respiratory care clinician would then set the rate at While an initial respiratory rate of 12 to 14 breath/min 12 or 13 breaths/min. A rate as low as 8 to 12 breaths/min should suffice, the respiratory care clinician can may be necessary to increase expiratory time and avoid estimate© Jones the &rate Bartlett (f) based Learning, on the desired LLC Vt and min- air trapping. Initial© Jones Fio2 of &0.50 Bartlett to 0.70 with Learning, a PEEP of ≤ LLC 5 cm H O (or as needed to offset autoPEEP) is a good place uteNOT ventilation FOR SALE ( V˙ e), where: OR DISTRIBUTION 2 NOT FOR SALE OR DISTRIBUTION to start followed by rapid adjustment based on Spo . V˙ e = Vt × f 2 Initial peak flow (e.g.,≥ 80 L/min) and inspiratory time and (e.g., should allow for an expiratory time sufficient to allow complete exhalation, and avoid air trappingg and f = V˙ e ÷ Vt © Jones & Bartlett Learning, LLC © JonesautoPEEP. & AsBartlett a point ofLearning, interest, if initial LLC time volume is NOT FOR SALEGiven ORthe patient’s DISTRIBUTION IBW of 73 kg, the target minute NOT8 mL/kgFOR IBWSALE and initialOR DISTRIBUTION rate is 12.5 breaths/min for any ventilation can be estimated at 100 mL/kg/min: patient, the target minute ventilation will be 100 mL/kg.

BOX 6-10 Initial© Ventilator Jones & Settings Bartlett for Learning, Assist-Control LLC Pressure-Control Ventilation© Jones (PC-CMV) & Bartlett Learning, LLC Initial ventilator settingsNOT FORfor most SALE adults OR receiving DISTRIBUTION pressure-control ventilation (PCV) inNOT the assist-control FOR SALE mode OR DISTRIBUTION are summarized as follows.

Ventilator Control Initial Setting

Pressure control Begin at 15 to 20 cm H2O and adjust to obtain an expired tidal volume of 8 mL/kg IBW (range 6 to 8 mL/kg). © Jones & BartlettDo not exceedLearning, Pplateau > 28LLC to 30 cm H2O. ARDS patients may© require Jones smaller & tidal Bartlett volumes as Learning, described in the LLC NOT FOR SALEARDS OR Clinical DISTRIBUTION Network Mechanical Ventilation Protocol Summary.NOTa FOR SALE OR DISTRIBUTION

Inspiratory time Begin with an inspiratory time setting of 0.8 sec (range 0.6–1.0 sec, although many patients do well with TI 0.8 to 1.2 sec. Adjust inspiratory time to ensure resultant flow meets or exceeds patient demand; avoid patient–ventilator asynchrony. If possible, the inspiratory time and pressure-control settings should allow the inspiratory flow to decrease to zero prior to the initiation of the expiratory phase, as observed on the ventilator’s graphics flow–time display. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Rate For assist-control (patient- or time-triggered ventilation) set the rate in the range of 12 to 14 breaths/min. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Trigger sensitivity Set pressure trigger –0.05 to –1.5 cm H2O. For flow, trigger set sensitivity at 1 to 2 L/min below baseline flow. Adjust trigger sensitivity to minimize trigger work without autocycling.

Flow waveform and PCV results in a square wave pressure pattern and a decreasing flow waveform. Pressure rise time should pressure rise time be adjusted based on observation of the ventilator graphics pressure–time curve to ensure that there is not a or slope ©pressure Jones overshoot & Bartlett or spike at Learning, the beginning of LLC inspiration, but that pressure rises quickly© Jones enough to& meetBartlett the Learning, LLC NOTpatient’s FOR spontaneous SALE inspiratory OR DISTRIBUTION demand in spontaneously breathing patients. NOT FOR SALE OR DISTRIBUTION

Fio2 (O2 Begin with 100% O2 for patients in obvious distress or conditions that may require high initial O2 concentrations percentage) (e.g., multiple trauma, severe pneumonia, ARDS, carbon monoxide poisoning, pulmonary edema, and post- resuscitation cardiac arrest). If recent arterial blood gases and the patient’s condition (e.g., COPD) suggest

that 100% O2 will not be necessary, you may begin with a moderate to high Fio2 (e.g., 0.40 to 0.70.) Careful © Jones & Bartlettassessment Learning, and monitoring, LLC (including continuous Spo2) should© guide Jones appropriate & Bartlett adjustment Learning,in Fio2 to obtain LLC NOT FOR SALEadequate OR DISTRIBUTIONarterial oxygenation at a safe oxygen concentration.NOT FOR SALE OR DISTRIBUTION

PEEP Initial PEEP setting for most patients is 5 cm H2O.

Humidification For heated humidification adjust to obtain a temperature at the proximal airway of 35°C–37°C. A heat moisture exchanger (HME) may suffice for some patients. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEAlarms OR and DISTRIBUTIONlimits Set appropriate volume and pressure alarmsNOT and FORlimits to SALEensure safe OR and DISTRIBUTIONeffective ventilation (see Table 6-4). aThe ARDSNet Protocol may be found at the ARDSNet website: www.ardsnet.org/files/ventilator_protocol_2008-07.pdf.

9781284139860_CH06_311_366.indd 356 26/02/19 12:33 PM Initial Ventilator Settings 357

© Jones & Bartlett Learning, LLC © Jones & BartlettCLINICAL Learning, FOCUS 6- LLC3 Initiating Assist-Control Pressure-Control Ventilation (aka PC-CMV) NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION The decision is made to intubate and ventilate a Given the patient’s IBW of 57 kg, the target minute female ARDS patient using assist-control pressure ventilation can be estimated at 100 mL/kg/min: control ventilation (aka PC-CMV). The patient is Desired V˙ e = IBW × 100 mL/kg/min = 57 kg × 65 inches (165 cm) in height. © Jones & Bartlett Learning, LLC100 mL/kg/min = 5700 mL/min© Jones (5.7 & L/min). Bartlett Learning, LLC Question 1. WhatNOT is an appropriateFOR SALE initial OR tidal DISTRIBUTION Given a target tidal volume ofNOT 456 mL, FOR the rateSALE needed OR DISTRIBUTION volume goal for this patient? to achieve this minute ventilation would be: Initial tidal volume should be 8 mL/kg IBW with a re- ˙ spiratory rate to achieve an appropriate minute ventila- f = Ve ÷ Vt = 5700 mL ÷ 456 mL = 12.5 breaths/min. tion V˙ e). Ideal body weight can be estimated based on The respiratory care clinician would then set the rate the© patient’sJones height& Bartlett using the Learning, following formula LLC for at 12 or 13 breaths/min.© Jones & Bartlett Learning, LLC females:NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Question 3. What is an appropriate initial pressure IBW = 45.5 + 2.3 (height in inches – 60) control, inspiratory time, and PEEP for this patient? If this patient is 65 in tall, her estimated IBW would be: Pressure control can be initially set at 15 cm H2O above PEEP; initial PEEP should be set at 5 cm H O. Tidal vol- IBW = 45.5 + 2.3 (65 – 60) = 57 kg (or 125 lb). 2 © Jones & Bartlett Learning, LLC © Jonesume delivery & Bartlett should then Learning, be immediately LLC assessed, and NOT FOR SALEVt OR (desired) DISTRIBUTION will be 8 mL/kg × 57 kg = 456 mL. NOTpressure-control FOR SALE levelOR adjusted DISTRIBUTION to achieve the target Vt of about 460 mL, while at the same time assuring that Question 2. What is an appropriate initial P < 30 cm H O. The ARDSNet Protocola suggests respiratory rate for this patient? plateau 2 that Vt then be reduced by 1 mL/kg at intervals of While an initial respiratory rate of 12 to 14 breath/min ≤ 2 hours until Vt is 6 mL/kg, or about 340 mL for this may suffice, the respiratory care clinician can estimate © Jones & Bartlett Learning, patient.LLC As Vt is reduced, appropriate© Jones increases & Bartlett in rate Learning, LLC the rate (f) based on the desired Vt and minute venti- NOT FOR SALE OR DISTRIBUTION(up to 35 breaths /min) shouldNOT be made FOR to maintain SALE V˙ORe. DISTRIBUTION lation (V˙ e) where: aThe ARDSNet Protocol may be found at the ARDSNet website: and f = V˙ e ÷ Vt www.ardsnet.org/files/ventilator_protocol_2008-07.pdf.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION that there is not a pressure spike on the pressure–time delivery.27 An inspiratory pause may also be used to ensure scalar at the beginning of inspiration. Rise time should a full inspiration (e.g., 1-sec inspiratory pause) before a also be adjusted such that initial gas flow to the patient chest radiograph is obtained.27 Caution should be em- meets or exceeds the patient’s inspiratory demand. With ployed beyond intermittent use of an inspiratory pause © Jones & PSVBartlett inspiratory Learning, gas flow LLCdeclines until the flow termina-© Jonesto measure & Bartlett Pplateau in spontaneouslyLearning, LLCbreathing patients to NOT FOR SALEtion criteria OR is DISTRIBUTION met (e.g., 5% to 25% of peak inspiratory NOTavoid FOR causing SALE or worseningOR DISTRIBUTION patient–ventilator asynchrony. flow). Expiratory sensitivity allows for adjustment of the An inspiratory pause will also increase mean airway pres- flow termination criterion to ensure the ventilator and sure, which could be problematic in patients with hemody- patient cycle are in sync in terms of the beginning of the namic instability. expiratory phase and cycle asynchrony does not occur. With pressure-control© Jones ventilation, & Bartlett the clinician Learning, can LLCExpiratory Time © Jones & Bartlett Learning, LLC set the rise time; the cycle variable is time. NOT FOR SALE OR DISTRIBUTIONExpiratory time for continuousNOT mandatory FOR SALE ventila -OR DISTRIBUTION tion is a function of inspiratory time, and respiratory Inspiratory Pause rate. Depending on the ventilator employed and the With VC-CMV and VC-IMV using set-point breath mode in use, inspiratory time may be set directly OR targeting (aka assist-control volume ventilation and vol- be determined by the tidal volume, peak flow, and flow ume© SIMV)Jones the & clinician Bartlett may Learning, set an inspiratory LLC pause waveform. ©Expiratory Jones time& Bartlett should allow Learning, for complete LLC or NOTinspiratory FOR hold. SALE Clinicians OR DISTRIBUTIONand automated monitor- exhalation NOTof inspired FOR gases SALE prior OR to the DISTRIBUTION initiation of ing systems routinely use a brief inspiratory pause (0.5 the next breath. This is especially important in patients to 2.0 sec) to measure patients’ Pplateau and calculate with obstructive lung disease (e.g., asthma, COPD) to compliance and resistance. avoid the development of autoPEEP and pulmonary The application of an inspiratory pause will increase over inflation. AutoPEEP may also cause patients to © Jones & inspiratoryBartlett time,Learning, decrease expiratoryLLC time, increase I:E © Joneshave difficulty & Bartlett triggering Learning, the ventilator. LLC Steps to cor- NOT FOR SALEratio, and OR increase DISTRIBUTION mean airway pressure. A brief inspira- NOTrect FOR for SALEautoPEEP OR include DISTRIBUTION using smaller tidal volumes, tory pause (e.g., 10%) may improve distribution of inspired decreasing inspiratory time, increasing expiratory gases, improve Pao2, and improve aerosol medication time, and reducing mandatory breath rate. Small

9781284139860_CH06_311_366.indd 357 20/02/19 5:00 PM 358 CHAPTER 6 Ventilator Initiation

© Jones &amounts Bartlett of Learning,extrinsic PEEP LLC to balance autoPEEP may © Jonesadult patients& Bartlett when Learning,using volume LLCcontrol or pressure be useful in patients have triggering difficulty. NOTcontrol FOR intermittentSALE OR mandatory DISTRIBUTION ventilation (aka VC- NOT FOR SALE OR DISTRIBUTION SIMV or PC-SIMV). Clinical Focus 6-4 provides an example using IMV/SIMV. I:E Ratio Fio (Oxygen Percentage) For ventilator initiation, we recommend that adjust- 2 ments in inspiratory© time, Jones expiratory & Bartlett time, and Learning, respi- LLCIn general, the safest option for© Jonesinitial oxygen & Bartlett con- Learning, LLC ratory rate achieve anNOT initial FOR I:E ratio SALE of 1:2 OR or lower. DISTRIBUTION centration (Fio2) is 1.0 (100%NOT O2) followed FOR SALE by patient OR DISTRIBUTION Methods to alter expiratory time and I:E ratio will vary, assessment, observation of changes in pulse oximetry 2 depending on the mode in use and available controls values (Spo2), and arterial blood gas measurement. (e.g., peak flow, respiratory rate, and inspiratory time). Beginning with 100% oxygen is especially important Box 6-11 summarizes initial ventilator settings for most in patients for whom little information is available or © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC BOXNOT 6-11 FOR Initial SALE Ventilator OR DISTRIBUTION Settings for Intermittent MandatoryNOT FOR Ventilation SALE OR DISTRIBUTION (VC-IMV or PC-IMV) Intermittent mandatory ventilation (IMV) intersperses mandatory breaths with spontaneous breathing. Sponta- neous breaths may be pressure supported using pressure-support ventilation (PSV) or automatic tube compen- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC sation (ATC). IMV is most commonly provided as volume-SIMV (aka VC-SIMV), although many modern critical NOT FOR SALEcare ventilators OR DISTRIBUTION allow for the use of pressure control-SIMVNOT (akaFOR PC-IMV) SALE or ORvarious DISTRIBUTION other targeting schemes. With SIMV, the ventilator is often initially adjusted to provide full ventilatory support. Initial ventilator settings for VC-IMV and PC-IMV are described below.

Ventilator Control© Jones Initial Setting& Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Tidal volume (Vt) and NOT ForFOR VC-IMV SALE initial Vt ORmay be DISTRIBUTION set at 8 mL/kg IBW (range 6 to 8 mL/kg); adjust toNOT ensure FOR Pplateau ≤SALE 28 to OR DISTRIBUTION inspiratory pressure 30 cm H2O. For PC-IMV set initial pressure-control value in the range of 15 to 20 cm H2O and adjust to achieve an adequate Vt.

Rate Initially set the IMV rate in the range of 12 to 14 breaths/min to achieve full ventilatory support.

©Peak Jones flow or inspiratory& Bartlett For Learning, volume ventilators LLC with peak flow control begin at 60© L/min Jones (range &40 Bartlettto 80 L/min). Learning, Adjust peak flow LLC to NOTtime FOR SALE ORensure DISTRIBUTION mandatory breath inspiratory flow meets or exceedsNOT patient FOR inspiratory SALE demand. OR ForDISTRIBUTION ventilators with inspiratory time control, begin with an inspiratory time setting of 0.8 sec (range 0.6 to 1.0 sec although

some patients do well with a TI 0.8 to 1.2 sec.) Adjust inspiratory time to ensure resultant flows meet or exceed patient demand and avoid patient–ventilator asynchrony.

Trigger sensitivity Set pressure trigger –0.05 to –1.5 cm H2O. For flow, trigger set sensitivity at 1 to 2 L/min below baseline © Jones & Bartlett Learning, LLCflow. Adjust trigger sensitivity to minimize© Jones trigger &work Bartlett without autocycling. Learning, LLC NOT FOR SALEFlow waveformOR DISTRIBUTION for the For VC-IMV begin with a decreasingNOT flow waveform FOR (downSALE ramp) OR and DISTRIBUTIONadjust, if needed. PC-IMV provides mandatory breaths a square wave-like pressure pattern with a decreasing flow waveform. The pressure waveform may be modified by adjusting the pressure rise time or slope.

Pressure support PSV generally is provided for spontaneous breaths in the range of 5 to 15 cm H2O to overcome the WOBI due to artificial airways. Automatic tube compensation (ATC) is also available on most modern critical care © Jonesventilators & Bartlettwhen used in Learning,the IMV/SIMV mode. LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Fio2 (O2 percentage) Begin with 100% O2 for patients in obvious distress or conditions that may require high initial O2 concentrations (e.g., multiple trauma, severe pneumonia, ARDS, carbon monoxide poisoning, pulmonary edema, and post-resuscitation cardiac arrest). If recent arterial blood gases and the patient’s condition

(e.g., COPD) suggest that 100% O2 will not be necessary, you may begin with a moderate to high Fio2 (e.g., 0.40 to 0.70). Careful assessment and monitoring (including continuous Spo2) should guide © Jones & Bartlettappropriate Learning, adjustment LLC in Fio2 to obtain adequate arterial© oxygenation Jones at& a Bartlettsafe oxygen concentration.Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION PEEP Initial PEEP setting for most patients is 5 cm H2O.

Humidification For heated humidification adjust to obtain a temperature at the proximal airway of 35°C to 37°C. A heat moisture exchanger (HME) may suffice for some patients. © Jones & BartlettAlarms and Learning, limits LLC Set appropriate volume and pressure© alarmsJones and limits& Bartlett to ensure safe Learning, and effective ventilationLLC (see Table 6-4). NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

9781284139860_CH06_311_366.indd 358 26/02/19 12:34 PM Initial Ventilator Settings 359

© Jones & Bartlett Learning, LLC © Jones & BartlettCLINICAL Learning, FOCUS 6-4 LLC Initiating Volume SIMV (VC-IMV) NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION A 38-year-old male arrived unresponsive in the emer- wave and down ramp flow waveform. We suggest Ini- gency department. He was suspected of taking an tiating ventilation with a down ramp. This may then overdose of an unknown substance. An arterial blood be adjusted following ventilator initiation. gas sample taken on room air reveals: Trigger sensitivity should be adjusted to ensure min- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC pH: 7.15 imal trigger work without autocycling. This generally NOT FOR SALE OR DISTRIBUTIONcorresponds to a pressure triggerNOT of 0.5FOR to –1.5SALE cm H OR2O DISTRIBUTION Paco2: 80 mmHg or flow trigger of 1 to 2 L/min below baseline bias flow. Pao : 38 mmHg 2 This patient was experiencing severe hypoxemia Sao2: 0.78 while breathing room air. Fio2 should be initiated at 1.0 HCO–: 28 mEq/L © Jones3 & Bartlett Learning, LLC or 100% O2.© Jones & Bartlett Learning, LLC The decision is made to intubate and ventilate this pa- NOT FOR SALE OR DISTRIBUTION Question 3.NOT What FORis an appropriate SALE OR initial DISTRIBUTION tient using volume SIMV (aka VC-IMV). The patient is ventilator setting for PSV? approximately 72 inches in height (6 ft). SIMV allows for spontaneous breathing to be inter- Question 1. What are appropriate initial ventilator spersed with mandatory IMV breaths. Some form of settings for rate (f) and tidal volume (Vt) this patient? © Jones & Bartlett Learning, LLC © Jonespressure & augmentationBartlett Learning, should be providedLLC with SIMV Initial Vt should be 8 mL/kg IBW. The patient’s ideal to compensate for the WOB due to the endotracheal NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONI body weight can be calculated using the following for- tube. Pressure augmentation may be provided using mula for males: PSV or automatic tube compensation. For PSV an ini- IBW = 50 + 2.3 (height in inches – 60) tial setting of 5 to 15 cm H2O is appropriate. Following ventilator initiation, the PSV needed to overcome the IBW = 50 + 2.3© (72Jones – 60) =& 77.6Bartlett kg (or 168 Learning, lb). resistanceLLC of the endotracheal© tube Jones can be & estimated Bartlett Learning, LLC as follows: Vt (desired) willNOT be 8 mL/kg FOR × SALE 77.6 kg =OR 620.8 DISTRIBUTION mL. NOT FOR SALE OR DISTRIBUTION PSV = (PIP – P ) × the patient’s spontaneous SIMV rate can be set in the range of 12 to 14 breaths/ plateau inspiratory flow rate. min to achieve a V˙e of 100 mL/min/kg IBW or 7760 mL/min. Following ventilator initiation, the patient’s peak in- © Jones & Bartlett Learning, LLC spiratory pressure© Jones (PIP) was& Bartlett 35 cm H O Learning, and plateau LLC Question 2. What are appropriate initial ventilator 2 NOT FOR SALE OR DISTRIBUTION pressure (P NOT) was FOR 21 cm SALE H O. During OR DISTRIBUTION spontaneous settings for this patient for peak flow, flow wave plateau 2 breathing in between mandatory SIMV breaths, the form, trigger sensitivity, and Fio ? 2 patient’s spontaneous inspiratory flow rate was 0.5 L/ The peak flow should be initially set at 60 L/min sec or 30 L/min. (range 40 to 80 L/min) and then adjusted to ensure PSV needed to overcome the WOB for this patient was: © Jones & Bartlettthat peak Learning, flow meets LLCor exceeds the patient’s inspira-© Jones & Bartlett Learning,I LLC NOT FOR SALEtory flow OR demand.DISTRIBUTION In ventilators with inspiratory timeNOT FORPSV = SALE (PIP – P plateauOR )DISTRIBUTION × the patient’s spontaneous control, an initial setting of 0.8 seconds (range 0.6 to inspiratory flow rate. 1.0 sec) is a good place to start. PSV = (35 cm H O – 21 cm H O) × Most modern critical care ventilators allow the 2 2 0.5 L/sec = 7 cm H O. respiratory care clinician to choose between a square 2 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION those in obvious distress. Disease states or conditions (Pao2 ≥ 60 mmHg, Sao2 ≥ 0.90) at a safe Fio2 (≤ 0.50 that may require high initial oxygen concentrations to 0.60). PEEP or CPAP may help achieve this goal. include severe pneumonia, ARDS, cardiac arrest fol- Some patients require mechanical ventilatory sup- lowing resuscitation, severe trauma, acute pulmonary port due to extra pulmonary conditions (e.g., anes- edema,© Jones near-drowning, & Bartlett smoke Learning, inhalation, LLCsuspected thesia, drug© overdose, Jones head& Bartlett trauma, neuromuscularLearning, LLC 27 aspiration,NOT FOR and carbon SALE monoxide OR DISTRIBUTION poisoning. Many of disease, andNOT spinal FOR cord injury).SALE These OR DISTRIBUTIONpatients may have these conditions increase pulmonary shunt, which gen- normal or near-normal lungs and may respond well to erally is less responsive to oxygen therapy. Fio2 should low to moderate initial concentrations of oxygen (e.g., then be quickly reduced (if possible) to avoid the devel- Fio2 of 0.40 to 0.50). Certain disease states associated opment of absorption atelectasis and oxygen toxicity. In with low V˙/Q˙ (but not shunt) also often respond well © Jones & manyBartlett patients Learning, Fio2 may beLLC rapidly titrated downward © Jonesto low &to Bartlettmoderate concentrationsLearning, LLC of oxygen therapy. NOT FOR SALEbased on OR Spo DISTRIBUTION2 monitoring and clinical assessment. TheNOT These FOR include SALE asthma, OR DISTRIBUTION emphysema, chronic bronchitis, end goal is to achieve an adequate arterial oxygen level and COPD. There may also be patients for whom a great

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© Jones &deal Bartlett of infor Learning,mation is available LLC including recent arterial© Jonescan be & set Bartlett by the respiratory Learning, care clinician.LLC These in- blood gases, suggesting adequate arterial oxygenation NOTclude FOR alarms SALE for ORmaximum DISTRIBUTION inspiratory pressure, low NOT FOR SALEcan be achieved OR DISTRIBUTION with low to moderate concentrations of pressure, low PEEP, high and low tidal volume, high and oxygen. In such cases, the clinician may choose to below minute ventilation, high and low respiratory rate, gin with a moderate concentration of oxygen (e.g., 40% oxygen percentage, humidification (temperature), and to 50%) based on prior blood gases and the patient’s apnea.27 The respiratory care clinician should adjust the clinical condition. That© Jones said, when & Bartlettin doubt begin Learning, with LLCventilator alarms to ensure patient© Jones safety &without Bartlett be- Learning, LLC 100% O2 and titrate downNOT based FOR on SALE the patient’s OR DISTRIBUTION oxygen coming a nuisance that may beNOT ignored. FOR SALE OR DISTRIBUTION saturation. Limits should be adjusted prior to ventilator initiation. The high-pressure limit and high-pressure alarm may can be set at 40 cm H2O prior to connecting the RC Insight patient to the ventilator to ensure that excessive pres- © Jones & Bartlett Learning, LLC sures are not© unintentionally Jones & Bartlett delivered. Learning, Pressures are LLC In general, the safest option for initial oxygen NOT FOR SALE OR DISTRIBUTION then reassessedNOT and FOR readjusted SALE following OR DISTRIBUTION initiation of concentration is 100% O2. mechanical ventilation with the goal of maintaining safe inspiratory pressures (e.g., Pplateau ≤ 28 to 30 cm H2O, PIP ≤40 cm H2O). Ventilator adjustments can be made PEEP and CPAP to reduce Pplateau and PIP if necessary following ventilator initiation. Table 6-4 lists suggested initial alarm set- © Jones & AsBartlett described Learning, earlier, patients LLC with acute restrictive © Jones & Bartlett Learning, LLC tings for adult mechanical ventilation. NOT FOR SALEpulmonary OR disease DISTRIBUTION (e.g., ARDS, severe pneumonia, NOT FOR SALE OR DISTRIBUTION or pulmonary edema) may develop hypoxemia due to Humidification unstable alveolar units that are collapsed. PEEP and CPAP can restore FRC, improve and maintain lung vol- Humidification should be provided for all patients re- umes, and improve oxygenation in such patients. PEEP/ ceiving invasive mechanical ventilatory support. Clini- CPAP should be considered© Jones in such & Bartlett patients with Learning, inad- LLCcal practice guidelines for heated© Jones humidifiers & Bartlett suggest Learning, LLC ± equate arterial oxygenNOT levels FOR (Pao 2SALE < 60 mmHg, OR DISTRIBUTION Sao2 an inspired gas temperature ofNOT 35°C FOR 2°C SALEto provide OR DISTRIBUTION < 0.90) on moderate to high oxygen concentrations humidity of 33 to 44 mg H2O/L at the patient Y con- (Fio2 ≥ 0.40). Smaller tidal volumes and appropriate nection. Heat and moisture exchangers (HME) may levels of PEEP are used in patients with ARDS to avoid be appropriate for some patients. HMEs should not be VILI. With ARDS, properly applied PEEP can stabilize used in patients receiving low tidal volumes as they add unstable© Jones lung units & Bartlett and avoid Learning, repetitive inflation LLC and additional mechanical© Jones dead& Bartlett space. HMEs Learning, are also not LLC deflationNOT FORof alveoli, SALE thus ORreducing DISTRIBUTION the likelihood of addi- recommendedNOT for FORuse with SALE noninvasive OR DISTRIBUTION ventilation. tional injury. Minimal PEEP/CPAP (3 to 5 cm H2O) generally is Patient Assessment used to maintain FRC and provide physiologic PEEP. Following initiation of mechanical ventilation, the pa- PEEP/CPAP may also be useful to offset autoPEEP and tient and patient–ventilator system should be carefully © Jones & reduceBartlett trigger Learning, work in some LLC patients. PEEP and CPAP © Jonesassessed. & Bartlett This should Learning, include physical LLC assessment, NOT FOR SALEmust be OR used DISTRIBUTION cautiously in patients with an already NOTbreath FOR sounds,SALE oximetry, OR DISTRIBUTION heart rate, blood pressure, elevated FRC as may occur with obstructive lung and observation of the cardiac monitor for cardiac disease (e.g., COPD, acute asthma). rhythm. The patient–ventilator system should be as- There are several approaches to the use of PEEP. sessed for ventilatory pressures, volumes, and flows. These include minimal PEEP, optimal or best PEEP, Arterial blood gases are usually obtained following compliance titrated PEEP,© Jones and the & use Bartlett of pressure– Learning, LLCinitial patient stabilization. Following© Jones assessment, & Bartlett Learning, LLC volume curves as partNOT of a lung-protectiveFOR SALE strategy.OR DISTRIBUTION For necessary changes in ventilatoryNOT parameters FOR SALE should OR be DISTRIBUTION initial ventilator setup, however, we suggest that almost made to ensure patient safety, comfort, oxygenation, all patients initially receive 5 cm H2O of PEEP/CPAP. and ventilation. Chapter 7 describes patient stabilization and ventilator adjustments following ventilator Alarms and Limits © Jones & Bartlett Learning, LLC initiation. © Jones & Bartlett Learning, LLC Modern critical care ventilators have sophisticated NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION alarms and monitoring systems. Ventilator alarms audi- Management of Specific Disease bly and visually notify ICU personnel that specific parameters are not met, and the patient–ventilator system States and Conditions should be assessed. Ventilator malfunction alarms are Management of patients with specific disease states and © Jones & normallyBartlett set Learning, by the manufacturer, LLC and include alarms © Jonesconditions & Bartlett can be complex. Learning, A few LLCof the key factors that for power loss, gas supply loss, electronic malfunction, NOT FOR SALE OR DISTRIBUTION NOTshould FOR beSALE considered OR DISTRIBUTIONfor mechanical ventilation in spe- or pneumatic malfunction. Certain patient status alarms cific situations are described below.

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© Jones &Asthma Bartlett Learning, LLC © Jonesventilation. & Bartlett Pressure Learning, support (5 to LLC 10 cm H2O) should be added to reduce the WOB due to the endotracheal NOT FOR SALEVentilation OR of DISTRIBUTION patients with severe asthma can be ex- NOT FOR SALE OR DISTRIBUTIONI tremely challenging. Lower tidal volumes (e.g., 6 to 8 tube. In the presence of autoPEEP resulting in triggering mL/kg IBW) should be used to reduce airway pressures difficulty, small amounts of extrinsic PEEP (3 to 5 cm H2O) may be applied, generally at about 50% to 80% of and avoid barotrauma; Pplateau should be maintained 36,37 the measured autoPEEP level. ≤ 30 cm H2O. Care must be taken to ensure adequate I:E ratios and© sufficientJones & expiratoryBartlett time Learning, to allow LLC © Jones & Bartlett Learning, LLC Severe Pneumonia for complete exhalationNOT in theFOR presence SALE of airwayOR DISTRIBUTION ob- NOT FOR SALE OR DISTRIBUTION struction. Lower respiratory rates (e.g., 10 to 12 breaths/ Mechanical ventilation may be necessary in pneumonia min) and higher inspiratory flow (e.g., 60 to 80 L/min) patients with severe respiratory failure to maintain oxy- 36,37 should be employed. Patient–ventilator asynchrony genation, ventilation, and acid-base balance. 36,39 Assist- should be avoided, and adjustment of tidal volume, control volume ventilation (VC-CMV) or volume-SIMV respiratory© Jones rate, & inspiratory Bartlett flow, Learning, inspiratory LLC time, and with pressure© supportJones will & Bartlettbe effective Learning, for most patients. LLC triggerNOT sensitivity FOR SALE may be necessary.OR DISTRIBUTION PEEP may be set at Initial Vt andNOT f may FOR be set SALE at 8 mL/kg OR IBWDISTRIBUTION and 14 to ≤ 5 cm H2O or at 50% to 80% of measured autoPEEP, if 16 breaths/min (respectively) with sufficient inspira- present. Some patients may require the use of paralytic tory flow and time settings (e.g., 60 to 80 L/min or 0.6 agents to control ventilation and permissive hypercapnia to 0.8 sec) to meet or exceed the patient’s inspiratory may sometimes be used to ensure airway pressures are demand.36,39 Unless recent blood gases and the patient’s © Jones & notBartlett excessive. Learning, Oxygen concentrations LLC should be adjusted to© Jonescondition & Bartlett indicate otherwise, Learning, it is LLCusually best to begin ≥ NOT FOR SALEachieve adequateOR DISTRIBUTION arterial oxygenation (e.g., Spo2 90%).NOTFio FOR2 at 1.0SALE and PEEP OR ofDISTRIBUTION 5 cm H2O. Fio2 and PEEP are then titrated to achieve an adequate arterial oxygenation at Acute Exacerbation of COPD a safe Fio2. Respiratory rate and tidal volume are adjusted to maintain adequate alveolar ventilation, while avoiding Mechanical ventilatory support may be necessary for excessive pressures (e.g., keep P < 30 cm H O). patients with severe exacerbation of COPD.36,38 NIV is plateau 2 © Jones & Bartlett Learning, LLCA lung-protective ventilation© strategy Jones is then& Bartlett employed Learning, LLC often a good option for these patients in the presence NOT FOR SALE OR DISTRIBUTION(see ARDS below).36,39 NOT FOR SALE OR DISTRIBUTION of acute respiratory acidosis. Other indications for NIV include severe dyspnea with respiratory muscle fatigue, Acute Respiratory Distress Syndrome increased WOB, or persistent hypoxemia unresponsive to supplemental oxygen therapy 36,38 NIV can be deliv- Patients with severe ARDS often require intubation ered© byJones facemask, & Bartlett nasal mask, Learning, or nasal pillows. LLC Initial and mechanical© Jones ventilation. & Bartlett Initially, very Learning, high oxygen LLC settingsNOT may FOR include SALE patient-triggered OR DISTRIBUTION breaths with concentrationsNOT may FOR be required, SALE and OR it generallyDISTRIBUTION is best inspiratory pressure in the range of 8 to 20 cm H2O to begin ventilation with 100% O2. As soon as is fea- and end-expiratory pressure in the range of 3 to 5 cm sible, Fio2 and PEEP are titrated to achieve adequate 36,38 H2O. Inspiratory pressure is then adjusted based on oxygenation at a safe Fio2. Lower tidal volumes are used measured tidal volume and respiratory rate. as part of a lung-protective strategy to avoid ventilator- 36,39 © Jones & BartlettSome patients Learning, may be LLCunable to tolerate NIV and re-© Jonesassociated & Bartlett lung injury. Learning, Ventilation LLC is usually initiated quire invasive mechanical ventilation. Initial ventilator to achieve full ventilatory support. Assist-control volume NOT FOR SALEsettings ORgenerally DISTRIBUTION include assist-control volume ventila-NOTventilation FOR SALE (aka VC-CMV) OR DISTRIBUTION or assist-control pressure/ tion with a tidal volume in the range of 6 to 8 mL/kg, control ventilation (aka PC-CMV) generally is effec- backup rate of 10 to 12 breaths/min, and inspiratory tive. Initial tidal volume may be set at 8 mL/kg IBW and flow of 60 to 80 L/min.36,38 Lower tidal volumes (e.g., respiratory rate adjusted to achieve an adequate minute 36,39 6 mL/kg), lower rates© (e.g., Jones 8 to 10), & Bartlettand higher Learning, initial LLCventilation (e.g., 100 mL/min/© kg Jones IBW). & Tidal Bartlett volume Learning, LLC peak flow (≥ 80 L/min or inspiratory time of 0.6 to is then progressively reduced to 7 mL/kg and then to 0.80 sec) may be necessaryNOT toFOR allow SALE for sufficient OR DISTRIBUTION 6 mL/kg over the next 1 to 3 hours.NOT36,39 FOR As tidal SALE volume OR DISTRIBUTION expiratory time. Care should be taken to avoid excessive is reduced, respiratory rate is increased to maintain pressures (e.g., maintain Pplateau ≤ 30 cm H2O). Trigger minute ventilation. Respiratory rate may be adjusted up sensitivity should be set to minimize trigger work with- to 35 breaths/min. Additional tidal volume adjustments < out© autotriggering. Jones & Bartlett Adequate Learning, expiratory time LLC should be may be made© toJones maintain & PBartlettplateau 30 Learning,cm H2O. PEEP LLC is providedNOT toFOR avoid SALE air trapping OR DISTRIBUTIONand autoPEEP. Moderate employed toNOT facilitate FOR alveolar SALE recruitment OR DISTRIBUTION and reduce Fio2s will often suffice (e.g., 0.40 to 0.50). Fio2 is ad- end expiratory alveolar collapse. Several PEEP strategies justed to maintain adequate arterial oxygen levels (e.g., have been suggested for ARDS patients. A good strategy Spo2 ≥ 92%, Pao2 ≥ 60 mmHg). Patients who rapidly for most patients is to adjust the PEEP to the lowest level trigger the ventilator in the assist-control mode may that results in an adequate Pao2 with an Fio2 ≤ 0.60. To © Jones & doBartlett well with Learning, SIMV. If SIMV LLC is employed, tidal volume, © Jonesbegin, &we Bartlett suggest in initialLearning, PEEP of LLC 5 to 8 cm H2O. Other NOT FOR SALEinspiratory OR peak DISTRIBUTION flow, and inspiratory time should be setNOT strategies FOR SALE to improve OR oxygenationDISTRIBUTION include recruitment at values similar to those used for assist-control volume maneuvers, pressure-control inverse-ratio ventilation,

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© Jones &and Bartlett prone p Learning,ositioning. Various LLC open lung and PEEP © Jones(IMV/SIMV). & Bartlett There Learning, are also a large LLC number of alterna- strategies are discussed in Chapters 7 and 8. Slightly NOTtive FOR modes SALE that haveOR beenDISTRIBUTION used to safely and effectively NOT FOR SALElarger tidal OR volumes DISTRIBUTION (e.g., 8 to 10 mL/kg) may be accept- provide ventilatory support to critically ill patients. 3 able if Pplateau remains ≤ 28 to 30 cm H2O. While these newer modes may have theoretic advantages, none has been shown to consistently improve Neuromuscular Disease patient outcomes as compared to more conventional Mechanical ventilatory© Jones support &is sometimesBartlett requiredLearning, LLCapproaches. © Jones & Bartlett Learning, LLC in patients with neuromuscularNOT FOR disease. SALE NIV OR can DISTRIBUTION often Ventilator initiation requiresNOT important FOR SALEchoices, OR DISTRIBUTION be effective in these patients and should be considered. including whether to provide invasive or noninvasive Acutely ill patients, however, may require invasive me- ventilation, type of airway or ventilator interface, and chanical ventilatory support.35 Assist-control volume whether to provide full or partial ventilatory support. ventilation (aka VC-CMV) or volume SIMV (VC-IMV) The respiratory care clinician must also select the mode to provide© Jones full ventilatory& Bartlett support Learning, generally LLC is effective. of ventilation© andJones specific & Bartlettventilator toLearning, be employed LLC Initially,NOT tidal FOR volume SALE may OR be setDISTRIBUTION at 8 mL/kg IBW with and the initialNOT ventilator FOR settings.SALE TheseOR DISTRIBUTION include initial a respiratory rate of 12 to 16 breaths/min to achieve a pressures, volumes, and flows provided, as well as oxy- desired minute ventilation (e.g., 100 mL/kg/min). 35 Ini- gen concentration, PEEP/CPAP, humidification, and tial inspiratory peak flow or inspiratory time may be set ventilator alarms and limits. Careful patient observation at 60 to 80 L/min (0.8 to 1.0 sec inspiratory time) with and assessment must follow ventilator initiation and © Jones & aBartlett down ramp Learning, flow waveform. LLC Trigger sensitivity should© Jonesappropriate & Bartlett adjustments Learning, made. The LLC goal is to ensure NOT FOR SALEbe adjusted OR to DISTRIBUTION ensure minimal trigger effort without auNOT- safe, FOR comfortable SALE OR support DISTRIBUTION that achieves adequate tissue tocycling. If IMV/SIMV is employed, pressure support oxygenation, alveolar ventilation, and acid-base homeo- starting at 5 cm H2O or automatic tube compensation stasis while minimizing the WOB. should be used to overcome the WOBI associated with the artificial airway. Often, patients with neuromus- Key Points cular disease, head trauma, or spinal cord injury have © Jones & Bartlett Learning, LLC■■ The primary function of a© mechanicalJones & ventilator Bartlett is toLearning, LLC otherwise normal lungs. These patients may initially NOT FOR SALE OR DISTRIBUTIONaugment or replace normalNOT ventilation. FOR SALE OR DISTRIBUTION only require moderate concentrations of oxygen (e.g., ■■ The four major indications for mechanical ventilation 0.40 to 0.50). Initial Fio may be 1.0 if the patient is in 2 are apnea, acute ventilatory failure, impending venti- distress or recent oximetry or blood gases suggest the latory failure, and severe oxygenation problems. need for a high initial oxygen concentration. Patients ■■ The major goals of mechanical ventilation are to pro- with neuromuscular disease and otherwise normal or © Jones & Bartlett Learning, LLC vide adequate© Jones alveolar & ventilation,Bartlett Learning,ensure adequate LLC near-normal lungs may benefit from the use of slightly NOT FOR SALE OR DISTRIBUTION tissue oxygenation,NOT FOR restore SALE and OR maintain DISTRIBUTION acid-base larger tidal volumes (e.g., 8 to 10 mL/kg) to prevent balance, and reduce the work of breathing. the development of atelectasis. Some neuromuscular ■■ The tank ventilator or iron lung was developed by care units begin with tidal volumes in the range of 10 Drinker, McCann, and Shaw at Harvard University to 12 mL/kg IBW and quadriplegic patients with high in 1928 and saw widespread use as the Emerson iron spinal cord injury (C3 to C4) may achieve more rapid © Jones & Bartlett Learning, LLC © Joneslung & during Bartlett the polio Learning, epidemics LLC in the 1940s and 50s. ventilator weaning with larger tidal volumes (> 20 mL/ NOT FOR SALE OR DISTRIBUTION NOT FOR■■ Negative-pressure SALE OR DISTRIBUTIONventilators maintain the natural kg IBW).40 airway, which allows patients to talk and eat; however, it is challenging to access the patient for proce- Summary dures, bathing, or turning and they are large, bulky, Indications for mechanical ventilation include apnea, and difficult to maneuver. acute ventilatory failure,© Jones impending & Bartlett ventilatory Learning, failure, LLC■■ The most common trigger© variables Jones are & timeBartlett and Learning, LLC and severe oxygenationNOT problems. FOR SALEMechanical OR ventila- DISTRIBUTIONpatient effort (i.e., patient NOTtriggered). FOR SALE OR DISTRIBUTION tory support may be provided using noninvasive venti- ■■ The common types of patient triggers are flow trigger lation or invasive ventilation requiring endotracheal and pressure trigger. intubation or tracheostomy. Mechanical ventilation ■■ Commonly used terms include assist breath, which is usually initiated to provide full ventilatory support; is patient triggered, control breath, which is time partial© Jones ventilatory & Bartlett support modes Learning, may be appropriateLLC in triggered,© and Jones assist-control & Bartlett, which Learning, can be patient LLC or certainNOT circumstances. FOR SALE OR DISTRIBUTION time triggered.NOT FOR SALE OR DISTRIBUTION Conventional modes of ventilation include assist- ■■ Controlled ventilation refers to time-triggered venti- control volume ventilation, also known as volume lation and requires apnea. control-continuous mandatory ventilation (VC-CMV); ■■ Cycle variables include volume, pressure, flow, and assist-control pressure-control ventilation, also known time. © Jones & asBartlett pressure Learning,control-continuous LLC mandatory ventilation © Jones■■ With & volume-controlBartlett Learning, ventilation, LLC a constant tidal NOT FOR SALE(PC-CMV) OR and DISTRIBUTION intermittent mandatory ventilation NOT FORvolume SALE is delivered; OR DISTRIBUTION however, inspiratory pressure

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■■ © Jones & Bartlettvaries with Learning, changes in theLLC patient’s compliance and © JonesHigh & airwayBartlett pressures Learning, may result LLC in barotrauma resistance. NOT FORor VILI. SALE OR DISTRIBUTION NOT FOR SALE■■ With ORpressure-control DISTRIBUTION ventilation, a constant inspi- ■■ The five major modes of ventilation are VC-CMV, ratory pressure is delivered; however, tidal volume PC-CMV, VC-IMV, PC-IMV, and PC-CSV. These varies with changes in the patient’s compliance, modes may be supplemented with PEEP or CPAP. resistance, and inspiratory effort. ■■ Advantages of VC-CMV include constant tidal vol- ■■ Pressure-support© ventilation Jones (PSV)& Bartlett is patient Learning, LLCume delivery in the face of© changes Jones in &compliance Bartlett Learning, LLC triggered, pressureNOT limited, FOR and SALE flow cycled. OR DISTRIBUTIONand resistance, provision ofNOT full ventilatory FOR SALE support, OR DISTRIBUTION ■■ Pressure-control ventilation (PCV) may be time or and reduced or eliminated work of breathing; how- patient triggered and is pressure limited and time ever, unsafe airway pressures may result. cycled. ■■ Advantages of PC-CMV include a constant inspira- ■■ With continuous mandatory ventilation (CMV), tory pressure in the face of changes in compliance every© Jones breath & is Bartletta mandatory Learning, breath. LLC and resistance,© Jones allowing & Bartlett for maintenance Learning, of a safe LLC ■■ ≤ WithNOT intermittent FOR SALE mandatory OR DISTRIBUTION ventilation (IMV), Pplateau NOT 28 to 30FOR cm H SALE2O. OR DISTRIBUTION mandatory breaths are interspersed with spontan- ■■ IMV incorporates spontaneous breathing, which main- eous breaths. tains ventilatory muscle activity and may help maintain ■■ With continuous spontaneous ventilation (CSV), the ventilatory muscle strength and coordination. patient initiates and terminates each breath; however, ■■ IMV may be used to provide full or partial ventila- © Jones & Bartlettinspiratory Learning, pressure augmentation LLC may be provided © Jonestory & support; Bartlett IMV Learning, may delay weaning LLC as compared NOT FOR SALE(e.g., ORPSV orDISTRIBUTION automatic tube compensation [ATC]). NOT FORto spontaneous SALE OR breathing DISTRIBUTION trials (SBTs). ■■ Noninvasive ventilation (NIV) may be indicated for ■■ Pressure-control inverse-ratio ventilation (PC-IRV) patients with acute exacerbation of COPD with hy- is a form of PC-CMV that may improve oxygenation percapnic acidosis, cardiogenic pulmonary edema, in patients with acute, severe hypoxemia that is unre- and acute hypoxemic respiratory failure. sponsive to conventional ventilation. ■■ NIV may also be useful© Jones to prevent & Bartlett postextubation Learning, LLC■■ Automatic tube compensation© Jones (ATC) is& designed Bartlett to Learning, LLC respiratory failureNOT and in FOR the support SALE of ORpatients DISTRIBUTION with overcome the imposed workNOT of breathing FOR SALE due to ORan DISTRIBUTION chronic hypoventilation due to neuromuscular or endotracheal or tracheostomy tube during spontane- chest wall disease. ous breathing. ■■ NIV should not be used in patients with cardiac or ■■ CPAP may help maintain FRC and improve oxygen- respiratory arrest, hemodynamic or cardiac instabil- ation in spontaneously breathing patients. ©ity, Jones or severely & impairedBartlett consciousness. Learning, LLC ■■ Other modes© Jones of ventilation & Bartlett include Learning, adaptive pres- LLC ■■ NOTIndications FOR for SALE endotracheal OR DISTRIBUTIONintubation include the in- sure control,NOT (APC), FOR mandatory SALE OR minute DISTRIBUTION ventilation ability to maintain a patent airway, inability to protect (MMV), adaptive support ventilation (ASV), airway the airway against aspiration, failure to ventilate, failure pressure-release ventilation (APRV), proportional to oxygenate, and anticipation of deterioration in the assist ventilation (PAV), automode, neutrally ad- patient’s condition that will lead to respiratory failure. justed ventilatory assist (NAVA), and high-frequency ■■ © Jones & BartlettEndotracheal Learning, intubation LLC is the most common © Jonesventilation. & Bartlett Learning, LLC method to achieve invasive ventilatory support; how- ■■ Adaptive pressure control (APC) automatically NOT FOR SALEever, ORtracheostomy DISTRIBUTION should be considered in certain NOT FORadjusts SALE pressure-control OR DISTRIBUTION or pressure-support levels patients. to achieve the desired tidal volume. ■■ Factors that should be considered when choosing a ■■ Pressure-regulated volume control (PRVC) and ventilator include clinical goals, the patient’s needs, volume support (VS) are considered forms of APC. ■■ availability, reliability,© Jones ventilator & features,Bartlett alarms Learning, and LLCMandatory minute ventilation© Jones (MVV) &automatically Bartlett Learning, LLC monitoring capabilities, modes available, cost, and adjusts the level of support provided to achieve a tar- (most importantly)NOT clinician’s FOR familiarity SALE OR with DISTRIBUTION the get minute ventilation. NOT FOR SALE OR DISTRIBUTION ventilator. ■■ Adaptive support ventilation (ASV) automatically ■■ The mode of ventilation can be described by the con- adjusts respiratory rate and inspiratory pressure to trol variable, breath sequence, and targeting scheme deliver the desired minute ventilation and minimize employed. the work of breathing. ■■ © Jones & Bartlett Learning, LLC ■■ © Jones & Bartlett Learning, LLC NOTCommon FOR control SALE variables OR DISTRIBUTIONare pressure control (PC) Airway pressure-releaseNOT FOR SALE ventilation OR DISTRIBUTION(APRV) allows and volume control (VC) for the primary breath. for two levels of CPAP that are time triggered and ■■ With full ventilatory support, adequate alveolar time cycled. ventilation is achieved even if the patient makes no ■■ Proportional assist ventilation (PAV) automatically spontaneous breathing efforts. adjusts the level of ventilatory support based on the ■■ © Jones & BartlettPartial ventilatory Learning, support LLC requires the patient to © Jonespatient’s & Bartlett inspiratory Learning, effort, calculated LLC work of breath- NOT FOR SALEprovide OR a portionDISTRIBUTION of the work needed to maintain anNOT FORing, andSALE clinician-set OR DISTRIBUTION percentage of support to be acceptable Paco2. provided.

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■■ © Jones & BartlettAutomode Learning, is a form of LLCIMV that incorporates a © Jones■■ Heated & Bartlett humidification Learning, should LLCbe provided at 35°C targeting scheme for both primary and secondary ± ° NOT FOR SALE OR DISTRIBUTION NOT FOR 2 C;SALE heat and OR moisture DISTRIBUTION exchangers (HME) may be breaths based on the modes selected. appropriate for some patients. ■■ Neurally adjusted ventilatory assist (NAVA) uses the ■■ A careful assessment should be done immediately electrical discharge from the diaphragm to trigger following ventilator initiation and appropriate venti- and cycle ventilator breaths. lator adjustments should be made to ensure patient ■■ High-frequency ventilation© Jones uses & Bartlettsmall tidal Learning,volumes LLCsafety, comfort and effective© Jonesgas exchange. & Bartlett Learning, LLC and very high respiratoryNOT FOR rates; SALE possible OR indications DISTRIBUTION NOT FOR SALE OR DISTRIBUTION include ARDS, bronchopleural fistula, and air leaks. ■■ There are currently four major types of HFV: high- References frequency positive-pressure ventilation (HFPPV), 1. Kacmarek RM, Stoller JK, Heuer AJ. Physiology of ventilatory high-frequency percussive ventilation (HFPV), high- support. In: Kacmarek RM, Stroller JK, Heuer AJ, Chatburn RL, frequency jet ventilation (HFJV), and high-frequency Kallet RH (eds.). Egan’s Fundamentals of Respiratory Care. 11th © Jones & Bartlett Learning, LLC ed. St. Louis,© Jones MO: Elsevier; & 2017:Bartlett 1016–1057. Learning, LLC oscillatory ventilation (HFOV). 2. Hess DR, MacIntyre NR, Galvin WF, Mishoe SC. Mechanical ■■ NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Assist-control volume ventilation, also known as ventilation. In: Hess DR, MacIntyre NR, Galvin WF, Mishoe SC VC-CMV, is a good initial mode choice for most (eds.). Respiratory Care: Principles and Practice. 3rd ed. Burling- patients. ton, MA: Jones & Bartlett Learning; 2016: 493–531. ■■ An acceptable alternative to assist-control volume 3. Petrucci N, Feo CD, Iacovelli W. Lung protective ventilation strategy for the acute respiratory distress syndrome. Cochrane Da- © Jones & Bartlettventilation Learning, is assist-control LLC pressure-control ventila-© Jonestabase & Bartlett Syst Rev. 2007;3:1–32. Learning, doi:10.1002/14651858.cd003844. LLC NOT FOR SALEtion (alsoOR knownDISTRIBUTION as PC-CMV); this mode requires NOT FORpub3. SALE OR DISTRIBUTION careful attention to the delivered tidal volume. 4. Chatburn RL, Volsko TA, Hess DR, et al. Mechanical ventilators: ■■ Pressure-support ventilation (PSV) can be used as classification and principles of operation. In: Hess DR, MacIntyre the primary mode of ventilation when patients have a NR, Galvin WF, Mishoe SC (eds.). Respiratory Care: Principles and Practice. 3rd ed. Burlington, MA: Jones & Bartlett Learning; consistent, stable, spontaneous ventilatory pattern. 2016: 462–492. ■■ SIMV is a serviceable© Jones option for& Bartlettinitial ventilator Learning, LLC5. Chatburn RL, El-Khatib M, Mireles-Cabodevila© Jones & BartlettE. A taxonomy Learning, LLC setup, although itNOT is used FOR less commonly. SALE OR DISTRIBUTIONfor mechanical ventilation: 10 fundamentalNOT FOR maxims. SALE Respir OR Care .DISTRIBUTION ■■ Initial tidal volume (adults) may be set in the range 2014;59(11):1747–1763. doi:10.4187/respcare.03057. 6. Hyzy RC, McSparron JI. Noninvasive ventilation in acute respira- of Vt 6 to 8 mL/kg IBW with the rate of 12 to 16 tory failure in adults. In: Parsons PE, Finlay G (eds.). UpToDate; breaths/min; smaller tidal volumes and faster rates July 2018. may be required for some ARDS patients. 7. Nagler J, Cheifetz IM. Noninvasive ventilation for acute and im- ■■ ©Tidal Jones volume & should Bartlett be adjusted Learning, to ensure LLC that pending respiratory© Jones failure & inBartlett children. In: Learning, Randolph AG, Wiley LLC JF Pplateau ≤ 28 to 30 cm H2O with a peak inspiratory (eds.). UpToDate; May 2018. NOT FOR SALE OR DISTRIBUTION 8. Hill NS, NOTKramer NFORR. Practical SALE aspects OR of nocturnalDISTRIBUTION noninvasive pressure (PIP) < 40 cm H2O. ■■ ventilation in neuromuscular and chest wall disease. In: Shefner Intermittent sigh breaths have been used in the past JM, Parsons PE (eds.). UpToDate; October 2018. to prevent development of atelectasis; routine use of 9. Davies JD, Niven AS, Hess DR, et al. Airway management. In: Hess PEEP may eliminate the need for an intermittent sigh. DR, MacIntyre NR, Galvin WF, Mishoe SC (eds.). Respiratory ■■ © Jones & BartlettPatient-triggered Learning, breaths LLC may be negative pressure © JonesCare: & BartlettPrinciples and Learning, Practice. 3rd ed. LLC Burlington, MA: Jones & or flow triggered; trigger sensitivity should be set to Bartlett Learning; 2016: 380–430. NOT FOR SALE OR DISTRIBUTION NOT10. FOR Laffer SALEty KA, Dillinger OR DISTRIBUTION R. Rapid sequence intubation: background, minimize trigger work while avoiding autotriggering. indications, contraindications. Medscape. May 24, 2018. Avail- ■■ Most modern ventilators allow for the adjustment of able at emedicine.medscape.com/article/80222-overview. rise time and expiratory sensitivity during PSV. 11. Orebaugh S, Snyder JV. Direct laryngoscopy and endotracheal in- ■■ An inspiratory pause allows for the measurement of tubation in adults. In: Wolfson AB, Hagberg CA (eds.). UpToDate; 2018 the plateau pressure (Pplateau) and calculation of com- © Jones & Bartlett Learning, LLC12. De Leyn P, Bedert L, Delcroix M,© et al.Jones Tracheotomy: & Bartlett clinical re Learning,- LLC pliance and resistance. view and guidelines. Eur J Cardio-Thoracic Surg. 2007;32:412–421. ■■ NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION I:E ratio should be 1:2 or lower for most patients. 13. Silvestri GA, Colice GL. Deciding timing and technique for tra- ■■ In general, the safest option for initial oxygen con- cheostomy. Contemp Intern Med. 1993;5(3):20–31. centration is 100%. 14. Epstein S. Anatomy and physiology of tracheostomy. Respir Care. ■■ PEEP/CPAP may improve and maintain lung vol- 2005;50(3):476–482. 15. Pierson, DJ. Tracheostomy and weaning. Respir Care. 2005;50(4): ©umes Jones and improve & Bartlett oxygenation Learning, in patients LLC with acute 526–533.© Jones & Bartlett Learning, LLC restrictive pulmonary disease. 16. Hyzy RC, McSparron JI. Overview of tracheostomy. In: King TE, ■■ NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Initial PEEP/CPAP of 5 cm H2O is appropriate for Finlay G (eds.). UpToDate; July 2018. most patients. 17. Blot F, Melot C. Indications, timing, and techniques of tracheos- ■■ Ventilator alarms and limits are to ensure patient tomy in 152 French ICUs. Chest. 2005;127(4):1347–1352. 18. Griffiths J, Barber VS, Morgan J, Young JD. Systematic review and safety and should be adjusted to alert ICU person- meta-analysis of studies of timing of tracheostomy in adult patients © Jones & Bartlettnel that theLearning, patient–ventilator LLC system should be © Jonesundergoing & Bartlett artificial Learning, ventilation. Br MedLLC J. 2005;330(7502):1243. NOT FOR SALEassessed. OR DISTRIBUTION NOT FORdoi:10.1136/bmj.38467.485671.ED SALE OR DISTRIBUTION

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19. Littlewood KE. Evidence-based management of tracheostomies 30. Cairo JM. Selecting the ventilator and the mode. In: Pilbeam © Jones & Bartlettin hospit alizedLearning, patients, Respir LLC Care. 2005;50(4):516–518. © JonesMechanical & Bartlett Ventilation: Learning, Physiological LLC and Clinical Applications. NOT FOR SALE20. Goldenber OR gDISTRIBUTION D, Ari EG, Golz A, et al. Tracheotomy complications:NOT FOR6th ed.SALE Maryland OR Heights, DISTRIBUTION MO: Elsevier; 2016: 58–79. a retrospective study of 1,130 cases. Otolaryngol Head Neck Surg. 31. Chatburn RL, Zhou S. Mechanical ventilation. In: Volscow TA, 2000;123(4):495–500. Chatburn RL, El-Khatib MF (eds.). Equipment for Respiratory 21. Trouillet JL, Luyt CE, Guiguet M, et al. Early percutaneous tra- Care. Burlington, MA: Jones & Bartlett Learning; 2016: 271–448. cheotomy versus prolonged intubation of mechanically ventilated 32. Cairo JM. Weaning and discontinuation from mechanical ventila- patients after cardiac surgery: a randomized trial. Ann Intern tion. In: Cairo JM (ed.). Pilbeam Mechanical Ventilation: Physio- Med. 2011;154(6):373–383.© Jones & Bartlett Learning, LLClogical and Clinical Applications©. 6thJones ed. Maryland & Bartlett Heights, MO: Learning, LLC 22. Rumbak MJ, NewtonNOT M, FORTruncale SALE T, et al. OR A prospective, DISTRIBUTION Elsevier; 2016: 387–412. NOT FOR SALE OR DISTRIBUTION randomized, study comparing early percutaneous dilatonal tra- 33. Verbrugghe W, Jorens PG. Neurally adjusted ventilatory assist: cheotomy to prolonged translaryngeal intubation (delayed tra- a ventilation tool or a ventilation toy? Respir Care. 2011;56(3): cheotomy) in critically ill medical patients. Crit Care Med. 2004; 327–335. doi:10.4187/respcare.00775. 32(8):1689–1694. 34. Harrington D. Volumetric diffusive ventilator. J Burn Care Res. 23. Bittner EA. Clinical use of neuromuscular blocking agents in 2009;1(1):175–176. https://doi.org/10.1097/BCR.0b013e3181923c44. ©critically Jones ill patients. & Bartlett In: Parsons Learning, PE, Finlay G, Crowley LLC M (eds.). 35. Eichenwald© EC.Jones Mechanical & Bartlett ventilation in Learning, neonates. In: Martin LLC R, NOTUpToDate FOR; December SALE 2017. OR DISTRIBUTION Kim MS (eds.).NOT UpToDate FOR ; SALEJune 2018. OR DISTRIBUTION 24. Hyzy RC. Physiologic and pathophysiologic consequences of 36. Hou P, Baez AA. Mechanical ventilation of adults in the emer- mechanical ventilation. In: Parsons PE, Finlay G (eds.). UpToDate; gency department. In: Walls RM, Grayzel J (eds.). UpToDate; April 2018. September 2017. 25. Hyzy RC, McSparron JI. Overview of mechanical ventilation. In: 37. Thomson CC, Hasegawa K. Invasive mechanical ventilation in Parsons PE, Finlay G (eds.). UpToDate; November 2018. adults with acute exacerbations of asthma. In: Manaker S, Holling- © Jones & 26.Bartlett Hyzy RC. Learning, Modes of mechanical LLC ventilation. In: Parsons PE, Finlay© Jonessworth & Bartlett H (eds.). UpToDate Learning,; September LLC 2018. G (eds.). UpToDate; 2018. 38. Allen GB. Invasive mechanical ventilation in acute respiratory NOT FOR SALE27. Kacmare ORk RM,DISTRIBUTION Stoller JK, Heuer AJ. Initiating and adjusting inNOT- FORfailure SALE complicating OR chronicDISTRIBUTION obstructive pulmonary disease. In: vasive ventilatory support. In: Kacmarek RM, Stroller JK, Heuer Stoller JK, Parsons PE, Finlay G (eds.). UpToDate; November AJ, Chatburn RL, Kallet RH (eds.). Egan’s Fundamentals of Res- 2016. piratory Care. 11th ed. St. Louis, MO: Elsevier; 2017:1078–1110. 39. Siegel MD, Hyzy RC. Mechanical ventila tion of adults in acute 28. Cairo JM. Special techniques and ventilatory support. In: Cairo respiratory distress syndrome. In: Parsons PE, Finlay G (eds.). JM (ed.). Pilbeam ©Mechanical Jones Ventilation: & Bartlett Physiological Learning, and LLCUpToDate; November 2017. © Jones & Bartlett Learning, LLC Clinical Applications. 6th ed. Maryland Heights, MO: Elsevier; 40. Peterson W, Barbalata L, Brooks C, et al. The effect of tidal vol- 2016:443–485. NOT FOR SALE OR DISTRIBUTIONumes on the time to wean personsNOT with FOR high SALEtetraplegia OR from DISTRIBUTION 29. Epstein SK, Walkey A. Methods of weaning from mechanical ven- ventilators. Spinal Cord. 1999;37(4):284–288. doi:10.1038/sj tilation. In: Parsons PE, Finlay G (eds.). UpToDate; July 2018. .sc.3100818.

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