DOCSLIB.ORG

Analysis of Alveolar Ventilation Inthe Newborn

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Analysis of Alveolar Ventilation Inthe Newborn Arch Dis Child: first published as 10.1136/adc.59.6.542 on 1 June 1984. Downloaded from Archives of Disease in Childhood, 1984, 59, 542-547 Analysis of alveolar ventilation in the newborn K SANDBERG, B A SJOQVIST, 0 HJALMARSON, AND T OLSSON Department of Paediatrics I, University of Goteborg and Research Laboratory of Medical Electronics, Chalmers University of Technology, Goteborg, Sweden SUMMARY Twelve healthy term infants were examined at the median ages of 21/2 and 26 hours. Their alveolar ventilation, efficiency of ventilation, functional residual capacity, and lung nitrogen elimination patterns were studied by means of a computerised nitrogen wash out method. The results showed that alveolar ventilation and functional residual capacity increased over the period studied. At the same time effective dead space decreased leaving minute ventilation unchanged. Distribution of ventilation did not change. In one critical phase at birth the lungs of the interrupted and repeated. A second test was not newborn take over the gas exchange function from performed for at least 15 minutes to allow for gas the placenta by establishing effective ventilation. In equilibration. The nitrogen concentration in the face the healthy infant sufficient function is achieved mask and the respiratory flow rate were sampled by within the first few breaths and steady state condi- a computer for subsequent calculations. The analy- tions are present after a few hours.' sis of the nitrogen wash out curve was performed on The efficiency of the ventilation obtained de- a PDP 11/40 computer and the software was written pends mainly on the volume of the ventilated in FORTRAN. airspace (functional residual capacity), the dead The total expired nitrogen volume during wash space, the distribution of ventilation, and the gas out was determined by integrating the product of the mixing efficiency within the lungs. These factors expired ventilatory flow rate and the nitrogen have not been studied in combination in newborn concentration in the expired air after compensation infants. In this investigation a computerised analysis for equipment delay and plethysmograph character- http://adc.bmj.com/ of nitrogen wash out curves was used to calculate istics. The functional residual capacity was obtained functional residual capacity and alveolar ventilation by dividing the total expired nitrogen volume after and to analyse gas mixing over the first day of life in the beginning of oxygen breathing by the end healthy, term infants. expiratory nitrogen concentration before the ni- trogen wash out. The method was designed to give Methods the lung volume in BTPS. The reproducibility of the functional residual A detailed description of the method is given capacity estimation was tested by means of a on September 27, 2021 by guest. Protected copyright. elsewhere.2 3 For the examination each infant was mechanical lung model inserted into the plethysmo- placed in the supine position in a 'face out' volume graph. This has been described in detail elsewhere.2 displacement body plethysmograph, with a pneumo- The known volume of the mechanical lung fell tachograph (Fleisch 1) in the wall. When the child within the 95% confidence interval of the estimated had adapted to the plethysmograph, respiratory volume when 10 repeated estimations were per- frequency, tidal volume, and minute ventilation formed. The coefficient of variation was 2-9%. were calculated. After this a face mask (dead space No correction was made for the elimination of 2 ml) was gently placed over the infant's face and tissue nitrogen in the estimation of functional mouth. A nitrogen analyser (Hewlett Packard residual capacity. According to Groom et al4 and model 47302A) and a system of tubings were Lundins one minute of oxygen breathing, which was connected to the face mask. During an expiration the approximate time for a nitrogen wash out test in the infant's breathing air was instantaneously this study, would add approximately 0-7 ml N2/kg changed to 100% oxygen and a nitrogen wash out body weight to the expired N2 volume implying an was performed until the end expired nitrogen overestimation of functional residual capacity by concentration was below 2%. If the infant was only about 1 ml/kg body weight. disturbed or if gas leaks were observed the test was A total lung nitrogen volume elimination curve 542 Arch Dis Child: first published as 10.1136/adc.59.6.542 on 1 June 1984. Downloaded from Analysis of alveolar ventilation in the newborn 543 was constructed with breath number on the abscissa In the analysis of the nitrogen elimination pattern (Fig. 1). This volume elimination curve was used for the best estimate of the observed elimination curve the further analysis of the nitrogen elimination was sought by fitting one, two, and three component pattern. In the ideal case the nitrogen elimination models to the linear curve by using the z transform,6 was assumed to be described by a single exponential multiple linear regression, least square fit, and F test function: of the residuals. The estimated curve was considered VLn=VLOe an=VLOWn (equation 1) to fit the original nitrogen elimination curve well (n=breath number, VLn=nitrogen volume remain- when the difference in curve areas-both curves ing in the lung after n breaths, VL0=nitrogen having the first point in common-was less than 5%. volume in the lung before the elimination, if the difference was more than 5% the wash out a=constant) where e-a=W is the dilution factor curve was considered insufficiently described by our defined as W=functional residual capacity/ exponential models. (functional residual capacity+tidal volume-dead The value of tidal volume minus dead space was space). obtained from the dilution factor in the best single Deviations from the ideal nitrogen elimination exponential fit to the wash out data according to pattern were assumed to be described by a sum of equation 1. As functional residual capacity and tidal exponential components with different dilution fac- volume were known, dead space could be estimated. tors. In this case the nitrogen elimination can be This estimated dead space is, by definition, the described as virtual part of the tidal volume not participating in VL, = F1VLOWL +F2VLOW2 +......... +FkVLOWkn the gas exchange between the inspired and alveolar (equation 2) gas, referred to as an effective dead space.7 In the elimination course dead space where VLO=FlVLO+F2VLO+....... +FkVLO and single exponential F1,F2. and Fk, are fractions of the total nitrogen may easily be estimated from the dilution factor. In lung volume. W1, W2...... and Wk are the dilution the multiple exponential course, however, the dead factors for the different exponential components in space changes continuously during nitrogen elimina- the elimination pattern. tion and cannot easily be described by a single value. 100 http://adc.bmj.com/ - E on September 27, 2021 by guest. Protected copyright. g e Breath No Fig, 1 Example ofthe nitrogen volume elimination curve with percentage ofthe total expired nitrogen volume on the ordinate and breath number on the abscisse. Arch Dis Child: first published as 10.1136/adc.59.6.542 on 1 June 1984. Downloaded from 544 Sandberg, Sjoqvist, Hjalmarson, and Olsson In these cases dead space was estimated from the dilution factor achieved by the best single exponen- tial least square fit to the data (equation 1). In this way the estimated dead space is the one obtained in LQJ q a g. .q a .3. an ideal system having the same lung volume and -w-- XN ZC5 4 ., z:_ -- 14 IC = tidal volume as the lung examined and represents a = r- WI, .: Z 7.c tr,, - OC rz. 7 weighted value of the continuously changing dead space. The alveolar ventilation was calculated as (tidal volume minus dead space)xrespiratory frequency At and the effective breath fraction as tidal volume v+,X- X~ ell minus dead space/tidal volume. The nitrogen clear- ance was calculated as the necessary ventilation for X dilution of the lung nitrogen to the end tidal nitrogen concentration of 2% divided by the calcu- _I lated functional residual capacity. In the statistical analysis Student's paired t test, 9 .5 Fisher's exact test, and analysis of covariance were A It a: used. Ninety five per cent confidence intervals for 0 the mean differences were calculated. Results are presented as mean (SEM). 11 .< Patients ., 0- -.-.cl Twelve vaginally delivered, healthy, term infants Oc W< ON Nt C CsC 11 were studied during the neonatal period. The I in median gestational age and range were 40 5 (38 to 42) weeks and the median birthweight and range Cr C' ., were 3-64 (2.95 to 4.15) kg. All infants were studied 'ii~ .5 r. twice at a median age and range of 2½/2 (2 to 4) and 0 http://adc.bmj.com/ 26 (21 to 33) hours. Six infants were boys and 6 were r-oNocNo r.n girls. No infant showed signs of respiratory disease (respiratory frequency greater than 60/minute, 11 cyanosis, retractions, or grunting). Nor were there E signs of perinatal asphyxia, cardiac disease, or o infection. The neonatal period was uneventful in all * infants. The investigation was approved by the local rz~X>~>'s > I; ethical committee and informed maternal consent 72 C) on September 27, 2021 by guest. Protected copyright. was obtained before the examination in all cases. _t IC I CI u Results '0 SZ The ventilatory parameters before and during the C'N ~ wC> nitrogen wash out are presented in Table 1. There .,. s 'A was an increase in minute ventilation during the 'No nitrogen wash out measurement compared with that .e1 found when the baby was sleeping in the plethysmo- C)eu graph without the face mask.
Load more

Recommended publications
  • Influence of a Six-Week Swimming Training with Added Respiratory
    International Journal of Environmental Research and Public Health Article Influence of a Six-Week Swimming Training with Added Respiratory Dead Space on Respiratory Muscle Strength and Pulmonary Function in Recreational Swimmers Stefan Szczepan 1,* , Natalia Danek 2 , Kamil Michalik 2 , Zofia Wróblewska 3 and Krystyna Zato ´n 1 1 Department of Swimming, Faculty of Physical Education, University School of Physical Education in Wroclaw, Ignacego Jana Paderewskiego 35, Swimming Pool, 51-612 Wroclaw, Poland; [email protected] 2 Department of Physiology and Biochemistry, Faculty of Physical Education, University School of Physical Education in Wroclaw, Ignacego Jana Paderewskiego 35, P-3 Building, 51-612 Wroclaw, Poland; [email protected] (N.D.); [email protected] (K.M.) 3 Faculty of Pure and Applied Mathematics, Wroclaw University of Science and Technology, Zygmunta Janiszewskiego 14a, C-11 Building, 50-372 Wroclaw, Poland; zofi[email protected] * Correspondence: [email protected]; Tel.: +48-713-473-404 Received: 5 July 2020; Accepted: 6 August 2020; Published: 8 August 2020 Abstract: The avoidance of respiratory muscle fatigue and its repercussions may play an important role in swimmers’ health and physical performance. Thus, the aim of this study was to investigate whether a six-week moderate-intensity swimming intervention with added respiratory dead space (ARDS) resulted in any differences in respiratory muscle variables and pulmonary function in recreational swimmers. A sample of 22 individuals (recreational swimmers) were divided into an experimental (E) and a control (C) group, observed for maximal oxygen uptake (VO2max). The intervention involved 50 min of front crawl swimming performed at 60% VO2max twice weekly for six weeks.
    [Show full text]
  • Calculation of Dead Space - Relevance in Critical Care
    CALCULATION OF DEAD SPACE - RELEVANCE IN CRITICAL CARE Kodati Rakesh Dead space • Dead space calculation • CO2 measurement • Effect of mechanical ventilation • ARDS • Recruitment & proning • Pulmonary embolism • Weaning DEAD SPACE CALCULATION Dead space • Volume of the airways and lungs that does not participate in gas exchange • Anatomical dead space – Volume of conducting airways – Upper airways, larynx, trachea, bronchi and bronchioles – Does not include respiratory bronchioles and alveoli • Physiologic dead space (VDphys) – Total volume of the lungs that does not participate in gas exchange – Includes anatomic dead space plus a functional dead space in the alveoli Dead space Dead space Difference b/w expected & actual composition of the effluent media Basis for calculating dead space and shunt Dead space Rileys 3 compartment model Alveoli groups according to V/Q ratios A – normal perfusion, no ventilation (shunt V/Q of 0) B – normal perfusion & ventilation (shunt V/Q of 1) C – normal ventilation, no perfusion (shunt V/Q of infinity) Physiological dead space (VD phys) Airway dead space (VD aw) Alveolar dead space (VD alv) Riley RL et al, J App Physiol 1949 Dead space Bohrs dead space • Danish physiologist Christian Bohr in 1891 • Mass balance calculation dilution of the expired gas by the inspiratory gas filling the conductive airways FACO2 - mean alveolar CO2 concentration sample of gas collected late in exhalation FECO2 fractional CO2 concentration in the total mixed exhaled breath H. Thomas Robertson, Eur Respir J 2015; 45 Tusman G et al, Anesth Analg 2012 Bohrs dead space • Fractions or partial pressures of CO2 are used interchangeably • FACO2 is the mean value of CO2 within the alveolar compartment • FE CO2 is calculated using formula VCO2/VT x (Pb – PH2O) H.
    [Show full text]
  • Dead Space and CO2 Elimination Related to Pattern of Inspiratory Gas
    Aboab et al. Critical Care 2012, 16:R39 http://ccforum.com/content/16/2/R39 RESEARCH Open Access Dead space and CO2 elimination related to pattern of inspiratory gas delivery in ARDS patients Jerome Aboab1, Lisbet Niklason2, Leif Uttman2, Laurent Brochard1,3 and Björn Jonson1,2* Abstract Introduction: The inspiratory flow pattern influences CO2 elimination by affecting the time the tidal volume remains resident in alveoli. This time is expressed in terms of mean distribution time (MDT), which is the time available for distribution and diffusion of inspired tidal gas within resident alveolar gas. In healthy and sick pigs, abrupt cessation of inspiratory flow (that is, high end-inspiratory flow (EIF)), enhances CO2 elimination. The objective was to test the hypothesis that effects of inspiratory gas delivery pattern on CO2 exchange can be comprehensively described from the effects of MDT and EIF in patients with acute respiratory distress syndrome (ARDS). Methods: In a medical intensive care unit of a university hospital, ARDS patients were studied during sequences of breaths with varying inspiratory flow patterns. Patients were ventilated with a computer-controlled ventilator allowing single breaths to be modified with respect to durations of inspiratory flow and postinspiratory pause (TP), as well as the shape of the inspiratory flow wave. From the single-breath test for CO2, the volume of CO2 eliminated by each tidal breath was derived. Results: A long MDT, caused primarily by a long TP, led to importantly enhanced CO2 elimination. So did a high EIF. Effects of MDT and EIF were comprehensively described with a simple equation.
    [Show full text]
  • Effect of Dead Space on Breathing Stability at Exercise in Hypoxia Eric Hermand, François Lhuissier, Jean-Paul Richalet
    Effect of dead space on breathing stability at exercise in hypoxia Eric Hermand, François Lhuissier, Jean-Paul Richalet To cite this version: Eric Hermand, François Lhuissier, Jean-Paul Richalet. Effect of dead space on breathing sta- bility at exercise in hypoxia. Respiratory Physiology & Neurobiology, 2017, 246, pp.26-32. 10.1016/j.resp.2017.07.008. hal-03189523 HAL Id: hal-03189523 https://hal.archives-ouvertes.fr/hal-03189523 Submitted on 3 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 Effect of dead space on breathing stability at exercise in hypoxia. 2 3 Eric Hermand1, François J Lhuissier1,2, Jean-Paul Richalet1 4 5 1Université Paris 13, Sorbonne Paris Cité, Laboratoire “Hypoxie et poumon”, EA2363, 6 Bobigny, France 7 2Assistance Publique-Hôpitaux de Paris, Hôpital Avicenne, Service de Physiologie, 8 explorations fonctionnelles et médecine du sport, 93009 Bobigny, France 9 10 11 Corresponding author [email protected] (J.P. Richalet) [email protected] (E. Hermand) 12 13 Laboratoire “Hypoxie & poumon”, EA2363 14 74 rue Marcel Cachin 15 93017 Bobigny Cedex, FRANCE 16 Tel: +33148387758 / Fax: +33148388924 17 18 19 Word count for manuscript: 2946 20 21 22 Key words: Control of ventilation, hypoxia, exercise, periodic breathing, breathing 23 instability, dead space, alveolar ventilation 24 25 26 27 28 29 30 Abstract 31 Recent studies have shown that normal subjects exhibit periodic breathing when submitted to 32 concomitant environmental (hypoxia) and physiological (exercise) stresses.
    [Show full text]
  • How Am I Supposed to Breathe with No Air? Nikki Lewis, CVT, VTS (ECC) 2016 ISVMA Conference Proceedings
    How am I supposed to breathe with no air? Nikki Lewis, CVT, VTS (ECC) 2016 ISVMA Conference Proceedings When the respiratory center begins to fail, functions such as oxygenation and elimination of carbon dioxide are compromised. This results in hypercapnia and hypoxemia. The major components of gas exchange are the lungs and the respiratory muscles which provide a force or pump to the lungs. If either one of these primary functions are compromised it can result in respiratory failure. Assessment of oxygenation and ventilation To accurately define respiratory failure, you must evaluate arterial blood gasses. A partial pressure of oxygen (PaO2) that’s less than 60mmHg and a partial pressure of carbon dioxide (PaCO2) of greater than 50mmHg define respiratory failure. The term partial pressure refers to the total pressure exerted by a single molecule of this gas. There are several molecules all combined in a cell; however, the partial pressure is the single gas’ pressure. Pulse oximetry is another method of quantifying oxygenation, although not as precise as arterial blood gasses. This is an indirect measurement of PaO2. A pulse oximetry measurement of 91-100% typically reflects a PaO2 of 80-100mmHg, which is a normal value. If the pulse oximetry falls below 91% this results in a rapid drop of the PaO2. Several factors can make the pulse oximetry reading false. These include pigmented tissues, motion and methemoglobinemia. Lastly, the measurement of end-tidal CO2 (ETCO2) will evaluate proper gas exchange. This is done by intubating the patient and using capnography. Capnography measures the expired CO2. Normal ETCO2 range is 35-45mmHg.
    [Show full text]
  • Miniaturization of Respiratory Measurement System in Artificial
    sensors Article Miniaturization of Respiratory Measurement System in Artificial Ventilator for Small Animal Experiments to Reduce Dead Space and Its Application to Lung Elasticity Evaluation Homare Yoshida 1,*, Yoshihiro Hasegawa 1, Miyoko Matsushima 2, Tomoshi Sugiyama 3, Tsutomu Kawabe 2 and Mitsuhiro Shikida 1 1 Department of Biomedical Information Sciences, Hiroshima City University, Hiroshima 731-3194, Japan; [email protected] (Y.H.); [email protected] (M.S.) 2 Division of Host Defense Sciences, Omics Health Sciences, Department of Integrated Health Sciences, Graduate School of Medicine, Nagoya University, Nagoya 461-0047, Japan; [email protected] (M.M.); [email protected] (T.K.) 3 Department of Thoracic Surgery, Graduate School of Medicine, Nagoya University, Nagoya 466-8560, Japan; [email protected] * Correspondence: [email protected] Abstract: A respiratory measurement system composed of pressure and airflow sensors was intro- duced to precisely control the respiratory condition during animal experiments. The flow sensor was a hot-wire thermal airflow meter with a directional detection and airflow temperature change compensation function based on MEMS technology, and the pressure sensor was a commercially available one also produced by MEMS. The artificial dead space in the system was minimized to × Citation: Yoshida, H.; Hasegawa, Y.; the value of 0.11 mL by integrating the two sensors on the same plate (26.0 mm 15.0 mm). A Matsushima, M.; Sugiyama, T.; Kawabe, balloon made of a silicone resin with a hardness of A30 was utilized as the simulated lung system T.; Shikida, M.
    [Show full text]
  • Underwater Physiology Is As Important As a Knowledge of Diving Gear and Proce- Dures
    CHAPTER 3 8QGHUZDWHU3K\VLRORJ\ 3-1 INTRODUCTION 3-1.1 Purpose. This chapter provides basic information on human physiology and anatomy as it relates to working in the underwater environment. Physiology is the study of the processes and functions of the body. Anatomy is the study of the structure of the organs of the body. 3-1.2 Scope. This chapter contains basic information intended to provide a fundamental understanding of the physiological processes and functions that are affected when humans are exposed to the underwater environment. A diver’s knowledge of underwater physiology is as important as a knowledge of diving gear and proce- dures. Safe diving is only possible when the diver fully understands the fundamental physiological processes and limitations at work on the human body in the underwater environment. 3-1.3 General. A body at work requires coordinated functioning of all organs and systems. The heart pumps blood to all parts of the body, the tissue fluids exchange dissolved materials with the blood, and the lungs keep the blood supplied with oxygen and cleared of excess carbon dioxide. Most of these processes are controlled directly by the brain, nervous system, and various glands. The indi- vidual is generally unaware that these functions are taking place. As efficient as it is, the human body lacks effective ways of compensating for many of the effects of increased pressure at depth and can do little to keep its internal environment from being upset. Such external effects set definite limits on what a diver can do and, if not understood, can give rise to serious accidents.
    [Show full text]
  • Diving Physiology 3
    Diving Physiology 3 SECTION PAGE SECTION PAGE 3.0 GENERAL ...................................................3- 1 3.3.3.3 Oxygen Toxicity ........................3-21 3.1 SYSTEMS OF THE BODY ...............................3- 1 3.3.3.3.1 CNS: Central 3.1.1 Musculoskeletal System ............................3- 1 Nervous System .........................3-21 3.1.2 Nervous System ......................................3- 1 3.3.3.3.2 Lung and 3.1.3 Digestive System.....................................3- 2 “Whole Body” ..........................3-21 3.2 RESPIRATION AND CIRCULATION ...............3- 2 3.2.1 Process of Respiration ..............................3- 2 3.3.3.3.3 Variations In 3.2.2 Mechanics of Respiration ..........................3- 3 Tolerance .................................3-22 3.2.3 Control of Respiration..............................3- 4 3.3.3.3.4 Benefits of 3.2.4 Circulation ............................................3- 4 Intermittent Exposure..................3-22 3.2.4.1 Blood Transport of Oxygen 3.3.3.3.5 Concepts of and Carbon Dioxide ......................3- 5 Oxygen Exposure 3.2.4.2 Tissue Gas Exchange.....................3- 6 Management .............................3-22 3.2.4.3 Tissue Use of Oxygen ....................3- 6 3.3.3.3.6 Prevention of 3.2.5 Summary of Respiration CNS Poisoning ..........................3-22 and Circulation Processes .........................3- 8 3.2.6 Respiratory Problems ...............................3- 8 3.3.3.3.7 The “Oxygen Clock” 3.2.6.1 Hypoxia .....................................3-
    [Show full text]
  • AIRWAY MANAGEMENT: HYPE ABOUT VENTILATION and the ANETHETIZED PATIENT Donna M
    AIRWAY MANAGEMENT: HYPE ABOUT VENTILATION AND THE ANETHETIZED PATIENT Donna M. Sisak, CVT, LVT, VTS (Anesthesia/Analgesia) Seattle Veterinary Specialists Kirkland, WA [email protected] “Life is not measured by the number of breaths we take but by the moments that take our breath away.” Author unknown An anesthetic event can be divided into the following components: premedication, induction, maintenance, and recovery. Each component is equally important and requires extreme vigilance by the anesthetist. Most of the drugs used (anesthetics/analgesics) throughout an anesthetic event are respiratory depressants. Until we obtain the patient’s airway (intubation) we really have no control over our patient’s ventilatory status and well-being. The patient is at risk of becoming hypoxic (inadequate O2 at the tissue level); eventually leading to other possible complications – aspiration pneumonia, decreased cardiac output (CO), decreased perfusion, and potentially cardiac arrest. Induction of an anesthetic event is defined as: drug administration to change the state of the patient from AWAKE to ANESTHETIZED and eventually securing the patient’s airway by placing a flexible rubber (endotracheal) down the trachea. Endotracheal intubation allows us to isolate the patient’s airway and support respiratory function during an anesthetic event. Safe anesthetic management requires adequate support and function to the respiratory system. It is the responsibility of the anesthetist to assure appropriate airway management during an anesthetic event. The anesthetist should be familiar with respiratory terminology as well as the equipment available for the patient. Endotracheal Intubation Endotracheal intubation is the placement of an endotracheal (ET) tube positioned between the vocal cords and down the trachea.
    [Show full text]
  • Q19 Describe the Types of Dead Space in the Respiratory System (50% Marks)
    Q19 Describe the types of dead space in the respiratory system (50% marks). Explain the consequences of increased dead space on gas exchange (50% mark) (March 2010) Dead space – that component of the tidal volume which does not take part in gas exchange. TYPES OF DEAD SPACE • Apparatus à dead space associated with synthetic breathing apparatus such as ETT and ventilator tubing • Anatomical à that volume of the conducting airways which does not take part in gas exchange (usually 2ml/kg or often estimated at 150ml). Anatomical DS can be measured using the modified Fowler’s method (inspiration of a normal tidal volume breath of 100% oxygen, then expiration against a spirometer and rapid gas analyser – the initial part of exhalation will be 100% oxygen which filled the conducting airways. As alveolar gas is expired, the % of measured CO2 (or N2) will rise and is graphed. A line is drawn such that Va = Vb and that line corresponds to the dead space volume. • Alveolar à that volume of gas reaching the alveoli which does not take part in gas exchange due to inadequate perfusion of those alveoli (this value may be significant in PE, low cardiac output state, or in the patient on PPV or who is hypotensive, in whom alveolar pressure in West’s Zone 1 is greater than pulmonary arterial pressure, compressing the vessels to produce dead space) • Physiological à the entire component of the tidal volume which does not eliminate CO2 (ie, anatomical + alveolar; in fit healthy people the physiological and anatomical values will be very similar).
    [Show full text]
  • 4 Physiology of Ventilation During Cardiac Arrest
    Chapter 4 / Physiology of Ventilation 39 4 Physiology of Ventilation During Cardiac Arrest Andrea Gabrielli, MD, A. Joseph Layon, MD, FACP, and Ahamed H. Idris, MD CONTENTS INTRODUCTION HISTORY OF ARTIFICIAL VENTILATION AND CPR TECHNIQUES PULMONARY PHYSIOLOGY DURING LOW BLOOD FLOW CONDITIONS VENTILATION DURING LOW BLOOD FLOW CONDITIONS TECHNIQUES OF VENTILATION DURING CPR BASIC AIRWAY MANAGEMENT ADVANCED AIRWAY SUPPORT SPECIALIZED AIRWAY DEVICES IN CPR LARYNGEAL MASK AIRWAY COMBITUBE PHARYNGOTRACHEAL LUMEN AIRWAY TRACHEOSTOMY AND CRICOTHYROIDOTOMY ALTERNATIVE METHODS OF VENTILATION AFTER SUCCESSFUL ENDOTRACHEAL INTUBATION TRANSPORT VENTILATORS MONITORING VENTILATION DURING CPR CONCLUSION REFERENCES INTRODUCTION Ventilation—the movement of fresh air or other gas from the outside into the lungs and alveoli in close proximity to blood for the efficient exchange of gases—enriches blood with oxygen (O2) and rids the body of carbon dioxide (CO2)by movement of alveolar gas from the lungs to the outside (1). The importance of ventilation in resuscitation is reflected in the “ABCs” (Airway, Breathing, Circulation), which is the recommended sequence of resuscitation practiced in a broad spectrum of illnesses including traumatic injury, unconsciousness, and respi- ratory and cardiac arrest (CA). Since the modern era of cardiopulmonary resuscitation (CPR) began in the early 1960s, ventilation of the lungs of a victim of CA has been assumed important for successful resuscitation. From: Contemporary Cardiology: Cardiopulmonary Resuscitation Edited by: J. P. Ornato and M. A. Peberdy © Humana Press Inc., Totowa, NJ 39 40 Cardiopulmonary Resuscitation Recently, this assumption has been questioned and is currently being debated (2). Several laboratory studies of CPR have shown no clear benefit to ventilation during the early stages of CA (3–5).
    [Show full text]
  • Respiratory Mechanics and Gas Exchanges in the Early Course of COVID‑19 ARDS: a Hypothesis‑Generating Study J.‑L
    Diehl et al. Ann. Intensive Care (2020) 10:95 https://doi.org/10.1186/s13613-020-00716-1 RESEARCH Open Access Respiratory mechanics and gas exchanges in the early course of COVID-19 ARDS: a hypothesis-generating study J.‑L. Diehl1,2* , N. Peron3, R. Chocron4,5, B. Debuc6, E. Guerot3, C. Hauw‑Berlemont3, B. Hermann3, J. L. Augy3, R. Younan3, A. Novara3, J. Langlais3, L. Khider7, N. Gendron1,8, G. Goudot5, J.‑F. Fagon3, T. Mirault4,9 and D. M. Smadja1,8 Abstract Rationale: COVID‑19 ARDS could difer from typical forms of the syndrome. Objective: Pulmonary microvascular injury and thrombosis are increasingly reported as constitutive features of COVID‑19 respiratory failure. Our aim was to study pulmonary mechanics and gas exchanges in COVID‑2019 ARDS patients studied early after initiating protective invasive mechanical ventilation, seeking after corresponding patho‑ physiological and biological characteristics. Methods: Between March 22 and March 30, 2020 respiratory mechanics, gas exchanges, circulating endothelial cells (CEC) as markers of endothelial damage, and D‑dimers were studied in 22 moderate‑to‑severe COVID‑19 ARDS patients, 1 [1–4] day after intubation (median [IQR]). Measurements and main results: Thirteen moderate and 9 severe COVID‑19 ARDS patients were studied after initiation of high PEEP protective mechanical ventilation. We observed moderately decreased respiratory system compliance: 39.5 [33.1–44.7] mL/cmH2O and end‑expiratory lung volume: 2100 [1721–2434] mL. Gas exchanges were characterized by hypercapnia 55 [44–62] mmHg, high physiological dead‑space (VD/VT): 75 [69–85.5] % and ventila‑ 2 tory ratio (VR): 2.9 [2.2–3.4].
    [Show full text]