Minute ventilation at different compression to ventilation ratios, different ventilation rates, and continuous chest compressions with asynchronous ventilation in a newborn manikin

Introduction: Resuscitation from out-of-cardiac arrest (OHCA) requires control of both chest compressions and lung ventilation. There are few effective methods for detecting ventilations during cardiopulmonary resuscitation. Thoracic impedance (TI) is sensitive to changes in lung air volumes and may allow detection of ventilations but has not been tested with concurrent mechanical chest compressions. Hypothesis: It is possible to automatically detect and characterize ventilations from TI changes during mechanical chest compressions. Methods: A cohort of 420 OHCA cases (27 survivors to hospital discharge) were enrolled in the Dallas-Fort Worth Center for Resuscitation Research cardiac arrest registry. These patients were treated with the LUCAS-2 CPR device and had concurrent TI and capnogram recordings from MRx (Philips, Andover, MA) monitor-defibrillators. We developed a signal processing algorithm to suppress chest compression artifacts from the TI signal, allowing identification of ventilations. We used the capnogram as gold standard for delivered ventilations. We determined the accuracy of the algorithm for detecting capnogram-indicated ventilations, calculating sensitivity, the proportion of true ventilations detected in the TI, and positive predictive value (PPV), the proportion of true ventilations within the detections. We calculated per minute ventilation rate and mean TI amplitude, as surrogate for tidal volume. Statistical differences between survivors and non-survivors were assessed using the Mann-Whitney test. Results: We studied 4331 minutes of TI during CPR. There were a median of 10 (IQR 6-14) ventilations per min and 52 (30-81) ventilations per patient. Sensitivity of TI was 95.9% (95% CI, 74.5-100), and PPV was 95.8% (95% CI, 80.0-100). The median ventilation rates for survivors and non-survivors were 7.75 (5.37-9.91) min -1 and 5.64 (4.46-7.15) min -1 (p<10 -3 ), and the median TI amplitudes were 1.33 (1.03-1.75) Ω and 1.14 (0.77-1.66) Ω (p=0.095). Conclusions: An accurate automatic TI ventilation detection algorithm was demonstrated during mechanical CPR. The relation between ventilation rate during mechanical CPR and survival was significant, but it was not for impedance amplitude.

Download Full-text

Abstract 122: Compression-Induced Ventilation Volumes Decrease with Chest Compression Depth and Prolonged CPR

Circulation ◽

10.1161/circ.130.suppl_2.122 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Simone Ordelman ◽

Paul Aelen ◽

Paul van Berkom ◽

Gerrit J Noordergraaf

Keyword(s):

Gas Exchange ◽

Endotracheal Tube ◽

Chest Compression ◽

Minute Ventilation ◽

Time Effect ◽

Chest Compressions ◽

Initial Value ◽

Compression Depth ◽

Minute Period ◽

Over Time

Introduction: Compression-induced ventilation may aid gas exchange during CPR. We hypothesized that the amount of gas moving in and out of the lungs depends on chest compression depth. Methods: VF was induced in five female, anesthetized and intubated pigs of about 30 kg. After 30 seconds of non-intervention time, chest compressions were started and maintained at a rate of 100 compressions per minute. Every two minutes chest compression depth was altered, resulting in 14 minutes of CPR with a depth sequence of 4 cm, 3 cm, 4 cm, 5 cm, 5.5 cm, 5 cm and 4 cm. Ventilations were performed manually with a bag-valve device 10 times per minute during continuous chest compressions by a dedicated expert. Airway flow was measured at the end of the endotracheal tube. Compression-induced ventilation was determined from the periods between the manual ventilations. The average compression-induced minute ventilation volume was determined over the last minute of each two minute period of CPR at each specific chest compression depth. Results: The compression-induced ventilation volume in the first period of CPR at 4 cm of depth was 1.6 ± 0.9 L/min (about 4% of total ventilation volume). The figure shows how the compression-induced ventilation volume decreases with increasing chest compression depth, relative to this initial value. CPR with a chest compression depth of 4 cm was performed three times in each pig, and the corresponding compression-induced ventilation volumes decreased with time. This suggested that there might be just a time effect (e.g. atelectasis). However, the final compression depth of 4 cm resulted in larger compression-induced ventilation volumes than the preceding 5 cm and 5.5 cm compression depths, indicating that the decreased volume over time could not purely be a time effect, but must also be an effect of the depth. Conclusion: In conclusion, compression-induced ventilation volume appears to decrease with deeper chest compressions as well as with prolonged CPR.

Download Full-text

Abstract P101: Comparison of Ventilation Rate Measured with Thoracic Bioimpedance and with Capnography during Out-of-Hospital Cardiopulmonary Resuscitation

Circulation ◽

10.1161/circ.118.suppl_18.s_1467-a ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Ahamed H Idris ◽

Sarah Beadle ◽

Mohamud Daya ◽

Dana Zive

Keyword(s):

Cardiac Arrest ◽

Ventilation Rate ◽

Rater Agreement ◽

Chest Compressions ◽

Intra Class Correlation ◽

Automated Software ◽

Ventilation Rates ◽

Patient File ◽

Hospital Cardiac Arrest ◽

Manual Review

Objective: To determine the ability of thoracic bioimpedance to measure ventilation rate during cardiac arrest and CPR. Methods: Philips MRx devices monitored 32 patients during out-of-hospital cardiac arrest and CPR. The devices recorded chest compressions with an accelerometer, continuous 1-lead EKG, thoracic bioimpedance, and continuous capnography. Of the 32 files, 4 were not used in this study because of incomplete recording. Two reviewers manually annotated ventilation waveforms independently using Laerdal QCPR software, which also automatically annotated ventilation through the bioimpedance channel. Reviewers manually measured ventilation rate (number of breaths/min) recorded with capnography for each 1 minute epoch, which were matched and compared with those measured through bioimpedance for each patient file (N = 28). A total of 585 1-minute epochs were measured and compared. We assessed intra-class correlation for 2 individual raters for ventilation rates measured with capnography and with annotated bioimpedance to establish inter-user reliability of measurements. Ventilation rate measured with capnography vs. bioimpedance was compared with simple regression. Results: The majority (60%) of ventilation rates measured with capnography and with automated software bioimpedance were within 2 breaths/min of each other. After manual annotation of the bioimpedance channel, 81% of 1-min epochs were within 2 breaths/min of rates measured with capnography. Ventilation rate measured with capnography had good correlation with bioimpedance (r = .82, p < .0001). Inter-rater agreement is estimated to be 0.96 for ventilation rate measured with capnography and 0.93 for rate measured with bioimpedance. Discussion: The software occasionally missed obvious ventilation waveforms and occasionally annotated waveforms obviously caused by chest compressions. Manual review and annotation improved the accuracy of ventilation rates measured with bioimpedance. Approximately 75% to 90% of recordings made with the Philips MRx device are expected to be useful for measurement. Conclusion: Ventilation rate measured with thoracic bioimpedance alone is acceptable using the Philips MRx device. Inter-rater agreement for measurements is excellent.

Download Full-text

A Cross-Over Trial Comparing Conventional to Compression-Adjusted Ventilations with Metronome-Guided Compressions

Prehospital and Disaster Medicine ◽

10.1017/s1049023x19000098 ◽

2019 ◽

Vol 34 (02) ◽

pp. 220-223 ◽

Cited By ~ 1

Author(s):

Dhimitri A. Nikolla ◽

Brandon J. Kramer ◽

Jestin N. Carlson

Keyword(s):

Cardiac Arrest ◽

Cardiopulmonary Resuscitation ◽

Null Hypothesis ◽

Basic Life Support ◽

Life Support ◽

Minute Ventilation ◽

Group Versus ◽

Time Intervals ◽

Minute Interval ◽

Ventilation Rates

Introduction:Hyperventilation during cardiopulmonary resuscitation (CPR) negatively affects cardiopulmonary physiology. Compression-adjusted ventilations (CAVs) may allow providers to deliver ventilation rates more consistently than conventional ventilations (CVs). This study sought to compare ventilation rates between these two methods during simulated cardiac arrest.Null Hypothesis:That CAV will not result in different rates than CV in simulated CPR with metronome-guided compressions.Methods:Volunteer Basic Life Support (BLS)-trained providers delivered bag-valve-mask (BVM) ventilations during simulated CPR with metronome-guided compressions at 100 beats/minute. For the first 4-minute interval, volunteers delivered CV. Volunteers were then instructed on how to perform CAV by delivering one breath, counting 12 compressions, and then delivering a subsequent breath. They then performed CAV for the second 4-minute interval. Ventilation rates were manually recorded. Minute-by-minute ventilation rates were compared between the techniques.Results:A total of 23 volunteers were enrolled with a median age of 36 years old and with a median of 14 years of experience. Median ventilation rates were consistently higher in the CV group versus the CAV group across all 1-minute segments: 13 vs 9, 12 vs 8, 12 vs 8, and 12 vs 8 for minutes one through four, respectively (P <.01, all). Hyperventilation (>10 breaths per minute) occurred 64% of the time intervals with CV versus one percent with CAV (P <.01). The proportion of time which hyperventilation occurred was also consistently higher in the CV group versus the CAV group across all 1-minute segments: 78% vs 4%, 61% vs 0%, 57% vs 0%, and 61% vs 0% for minutes one through four, respectively (P <.01, all).Conclusions:In this simulated model of cardiac arrest, CAV had more accurate ventilation rates and fewer episodes of hyperventilation compared with CV.Nikolla DA, Kramer BJ, Carlson JN. A cross-over trial comparing conventional to compression-adjusted ventilations with metronome-guided compressions. Prehosp Disaster Med. 2019;34(2):220–223

Download Full-text

Abstract 371: Using Defibrillator Bioimpedance Waveforms to Measure Ventilation During Continuous Chest Compression CPR

Circulation ◽

10.1161/circ.142.suppl_4.371 ◽

2020 ◽

Vol 142 (Suppl_4) ◽

Author(s):

Teresa R Gordon ◽

Enrique Rueda ◽

Elisabete Aramendi ◽

Unai Irusta ◽

Pamela Owens ◽

...

Keyword(s):

Chest Compression ◽

Heart Rhythm ◽

Spontaneous Circulation ◽

Chest Compressions ◽

Emergency Responders ◽

Advanced Airway ◽

Lower Amplitude ◽

Waveform Amplitude ◽

Ventilation Rates

Introduction: For patients with out of hospital cardiac arrest, prompt return of circulation and ventilation is vitally important for survival. Techniques and devices have been developed to ensure emergency responders are providing high quality chest compression, but there has been little progress in the area of ventilation. Until an advanced airway is placed, there has been no practical way to measure ventilation. The aim of this study is to develop a method to measure ventilation during continuous chest compressions cardiopulmonary resuscitation (CPR) that can be used to monitor and improve quality of ventilation during out of hospital CPR. Hypothesis: Defibrillator transthoracic bioimpedance can be used to identify ventilation waveforms prior to placement of an advanced airway during continuous chest compressions CPR. Methods: We examined 391 patients’ defibrillator files from four Resuscitation Outcomes Consortium sites for the presence of waveforms that met previously developed criteria and were manually annotated. Criteria for an acceptable ventilation waveform were: waveform amplitude ≥0.5 Ohm and waveform duration ≥1 sec. We recorded the number of ventilations, return of spontaneous circulation, initial heart rhythm, and ventilation rates. Following annotation, 333 of the 391 patients’ files had the necessary intubation time recorded and an automated program precisely measured the amplitude and duration of each ventilation. We determined mean (±SD) waveform amplitude and duration of inflation and deflation pre and post airway placement. Significance was determined using Wilcoxon ranked sum test. Results: Comparing the pre and post airway measurements did not result in any significant differences, except in duration of inflation, which was 1.06 ± 0.41 sec and 1.11 ± 0.52 sec, respectively, (p <0.001). Ventilation waveforms had significantly lower amplitude and shorter duration during chest compressions than during pauses in compressions. Conclusion: Defibrillator transthoracic bioimpedance can be used to identify and monitor ventilations during continuous chest compressions CPR. Ventilation waveforms have lower amplitudes and shorter durations during chest compressions than during pauses in compressions.

Download Full-text

Influence of air temperature on ventilation rates and thermoregulation of a flying bat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1991.260.5.r960 ◽

1991 ◽

Vol 260 (5) ◽

pp. R960-R968 ◽

Cited By ~ 3

Author(s):

S. P. Thomas ◽

D. B. Follette ◽

A. T. Farabaugh

Keyword(s):

Heat Loss ◽

Minute Ventilation ◽

Ventilation Rate ◽

Evaporative Heat Loss ◽

Breathing Frequency ◽

Significant Extent ◽

Metabolic Heat ◽

Air Temperatures ◽

Phyllostomus Hastatus ◽

Ventilation Rates

To assess the involvement of the ventilatory system in thermoregulation during flight, breathing frequencies and tidal volumes were measured from three Phyllostomus hastatus undertaking steady wind tunnel flights at a constant speed over a range of air temperatures (Ta) from 17.7 to 31.1 degrees C. Mean breathing frequency was independent of Ta, and tidal volume increased only modestly with increasing Ta. Consequently, minute ventilation rate increased insignificantly over the range of Ta values investigated. Mean rectal temperature showed a direct linear relation to Ta and increased significantly from 39.1 to 41.9 degrees C over the range of Ta values investigated. The highest rectal temperatures measured from flying P. hastatus are approximately 3 degrees C less than those of flying birds. In contrast to flying birds, flying P. hastatus does not modulate its rate of respiratory evaporative heat loss to any significant extent in response to environmental heat stress and only loses an estimated 14% of its metabolic heat load by this route. Cutaneous heat loss channels must therefore be very important to these animals. Some reasons for the observed differences in the thermoregulatory responses of flying bats and birds are discussed as well as the relative advantages and limitations of each group's solutions to their thermoregulatory challenges.

Download Full-text

Cardiopulmonary Resuscitation

Anesthesiology ◽

10.1097/00000542-199904000-00022 ◽

1999 ◽

Vol 90 (4) ◽

pp. 1078-1083 ◽

Cited By ~ 26

Author(s):

Zoltan G. Hevesi ◽

David N. Thrush ◽

John B. Downs ◽

Robert A. Smith

Keyword(s):

Cardiopulmonary Resuscitation ◽

Airway Pressure ◽

Positive Pressure Ventilation ◽

Minute Ventilation ◽

Intermittent Positive Pressure Ventilation ◽

Positive Pressure ◽

Chest Compressions ◽

Aortic Blood Pressure ◽

To Receive ◽

Co2 Elimination

Background Conventional cardiopulmonary resuscitation (CPR) includes 80-100/min precordial compressions with intermittent positive pressure ventilation (IPPV) after every fifth compression. To prevent gastric insufflation, chest compressions are held during IPPV if the patient is not intubated. Elimination of IPPV would simplify CPR and might offer physiologic advantages, but compression-induced ventilation without IPPV has been shown to result in hypercapnia. The authors hypothesized that application of continuous positive airway pressure (CPAP) might increase CO2 elimination during chest compressions. Methods After appropriate instrumentation and measurement of baseline data, ventricular fibrillation was induced in 18 pigs. Conventional CPR was performed as a control (CPR(C)) for 5 min. Pauses were then discontinued, and animals were assigned randomly to receive alternate trials of uninterrupted chest compressions at a rate of 80/min without IPPV, either at atmospheric airway pressure (CPR(ATM)) or with CPAP (CPR(CPAP)). CPAP was adjusted to produce a minute ventilation of 75% of the animal's baseline ventilation. Data were summarized as mean +/- SD and compared with Student t test for paired observations. Results During CPR without IPPV, CPAP decreased PaCO2 (55+/-28 vs. 100+/-16 mmHg) and increased SaO2 (0.86+/-0.19 vs. 0.50+/-0.18%; P < 0.001). CPAP also increased arteriovenous oxygen content difference (10.7+/-3.1 vs. 5.5+/-2.3 ml/dl blood) and CO2 elimination (120+/-20 vs. 12+/-20 ml/min; P < 0.01). Differences between CPR(CPAP) and CPR(ATM) in aortic blood pressure, cardiac output, and stroke volume were not significant. Conclusions Mechanical ventilation may not be necessary during CPR as long as CPAP is applied. Discontinuation of IPPV will simplify CPR and may offer physiologic advantage.

Download Full-text

Mask leak increases and minute ventilation decreases when chest compressions are added to bag ventilation in a neonatal manikin model

Acta Paediatrica ◽

10.1111/apa.12573 ◽

2014 ◽

Vol 103 (5) ◽

pp. e182-e187

Author(s):

Mark B. Tracy ◽

Dharmesh Shah ◽

Murray Hinder ◽

Jan Klimek ◽

James Marceau ◽

...

Keyword(s):

Minute Ventilation ◽

Chest Compressions

Download Full-text

Ozone dose–response effects of varied equivalent minute ventilation rates

Journal of Exposure Science & Environmental Epidemiology ◽

10.1038/sj.jea.7500086 ◽

2000 ◽

Vol 10 (3) ◽

pp. 217-226 ◽

Cited By ~ 9

Author(s):

WILLIAM C ADAMS

Keyword(s):

Dose Response ◽

Minute Ventilation ◽

Ozone Dose ◽

Ventilation Rates

Download Full-text

Abstract 45: A Mathematical Model of Ventilation, Perfusion, and Oxygenation in Low-Flow States

Circulation ◽

10.1161/circ.116.suppl_16.ii_932-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Daniel P Davis ◽

Paul W Davis

Keyword(s):

Mathematical Model ◽

Minute Ventilation ◽

Intrathoracic Pressure ◽

Ventilation Rate ◽

Low Flow ◽

Inflection Points ◽

Volume Relationship ◽

Pressure Volume Relationship ◽

Ventilation Rates ◽

Flow States

Background: Recent investigations underscore the critical importance of ventilation strategies on resuscitation outcomes. In low perfusion states, such as cardiac arrest and traumatic shock, the rise in intrathoracic pressure that accompanies positive-pressure ventilation (PPV) can significantly impede venous return and lead to a decrease in cardiac output. The optimal ventilation strategy in these “low-flow” states remains unclear. Objectives: To create a mathematical model of perfusion and oxygenation to predict the effects of PPV with both normotension and hypotension. Methods: The lung pressure-volume relationship was modeled using a novel formula allowing manipulation of various lung characteristics, including vital capacity, compliance, and the upper and lower inflection points. A separate formula was then derived to predict mean intrathoracic pressure for a given minute ventilation using the pressure-volume formula. The addition of positive end-expiratory pressure was also modeled. Finally, a formula was derived to model oxygen absorbance as a function of alveolar surface area and flow based on ventilation rate and mean intrathoracic pressure. Results: Mathematical models of the lung pressure-volume relationship, mean intrathoracic pressure, and absorbance were successfully derived. Manipulation of vital capacity, compliance, upper and lower inflection points, positive end-expiratory pressure, and minute ventilation allowed prediction of optimal ventilation rate and tidal volume for a normal and an ARDS lung. For a normal lung, optimal values for both mean intrathoracic pressure and absorption were achieved with a ventilation rate of 4 breaths/min. A decrease in the upper inflection point or increase in minute ventilation resulted in faster optimal ventilation rates, although none exceeded 14 breaths/min. Conclusions: A mathematical model of ventilation was successfully created allowing manipulation of multiple variables related to lung compliance and ventilation strategy. This model suggests the use of lower ventilation rates with larger tidal volumes to minimize the hemodynamic effects of PPV and maximize oxygen absorbance.

Download Full-text