A clinical observational study analysing the factors associated with hyperventilation during actual cardiopulmonary resuscitation in the emergency department

Assessment of a new volumetric capnography-derived parameter to reflect compression quality and to predict return of spontaneous circulation during cardiopulmonary resuscitation in a porcine model

We aimed to evaluate a volumetric capnography (Vcap)-derived parameter, the volume of CO2 eliminated per minute and per kg body weight (VCO2/kg), as an indicator of the quality of chest compression (CC) and to predict the return to spontaneous circulation (ROSC) under stable ventilation status. Twelve male domestic pigs were utilized for the randomized crossover study. After 4 min of untreated ventricular fibrillation (VF), mechanical cardiopulmonary resuscitation and ventilation were administered. Following 5-min washout periods, each animal underwent two sessions of experiments: three types of CC quality for 5 min stages in the first session, followed by advanced life support, consecutively in two sessions. Different CC quality had a significant effect on the partial pressure of end-tidal carbon dioxide (PetCO2), VCO2/kg, aortic pressure (mean), aortic systolic pressure, aortic diastolic pressure, right atrial pressure (mean), and carotid blood flow (P < 0.05). With the improvement in CC quality, the values of PetCO2 and VCO2/kg also increased, and the difference between the groups was statistically significant (P < 0.05). The Spearman rank test revealed a significant correlation between the Vcap-derived parameters and hemodynamics. PetCO2 and VCO2/kg have similar capabilities for discriminating survivors from non-survivors, and the area under the curve for both was 0.97. VCO2/kg had similar performance as PetCO2 in reflecting the quality of CC and prediction of achieving ROSC under stable ventilation status in a porcine model of VF-related cardiac arrest. However, VCO2/kg requires a longer time to achieve a stable state after adjusting for quality of CC than PetCO2.

Prehospital Cardiac Arrest Airway Management: An NAEMSP Position Statement and Resource Document

Airway management is a critical component of out-of-hospital cardiac arrest (OHCA) resuscitation. Multiple cardiac arrest airway management techniques are available to EMS clinicians including bag-valve-mask (BVM) ventilation, supraglottic airways (SGAs), and endotracheal intubation (ETI). Important goals include achieving optimal oxygenation and ventilation while minimizing negative effects on physiology and interference with other resuscitation interventions. NAEMSP recommends:Based on the skill of the clinician and available resources, BVM, SGA, or ETI may be considered as airway management strategies in OHCA.Airway management should not interfere with other key resuscitation interventions such as high-quality chest compressions, rapid defibrillation, and treatment of reversible causes of the cardiac arrest.EMS clinicians should take measures to avoid hyperventilation during cardiac arrest resuscitation.Where available for clinician use, capnography should be used to guide ventilation and chest compressions, confirm and monitor advanced airway placement, identify return of spontaneous circulation (ROSC), and assist in the decision to terminate resuscitation.

Effects of Changes in Inspiratory Time on Inspiratory Flowrate and Airway Pressure during Cardiopulmonary Resuscitation: A Manikin-Based Study

Objectives: Given that cardiopulmonary resuscitation (CPR) is an aerosol-generating procedure, it is necessary to use a mechanical ventilator and reduce the number of providers involved in resuscitation for in-hospital cardiac arrest in coronavirus disease (COVID-19) patients or suspected COVID-19 patients. However, no study assessed the effect of changes in inspiratory time on flowrate and airway pressure during CPR. We herein aimed to determine changes in these parameters during CPR and identify appropriate ventilator management for adults during CPR.Methods: We measured changes in tidal volume (Vt), peak inspiratory flow rate (PIFR), peak airway pressure (Ppeak), mean airway pressure (Pmean) according to changes in inspiratory time (0.75 s, 1.0 s and 1.5 s) with or without CPR. Vt of 500 mL was supplied (flowrate: 10 times/min) using a mechanical ventilator. Chest compressions were maintained at constant compression depth (53 ± 2 mm) and speed (102 ± 2/min) using a mechanical chest compression device.Results: Median levels of respiratory physiological parameters during CPR were significantly different according to the inspiratory time (0.75 s vs. 1.5 s): PIFR (80.8 [73.3 – 87.325] vs. 70.5 [67 – 72.4] L/min, P < 0.001), Ppeak (54 [48 – 59] vs. 47 [45 – 49] cmH₂O, P < 0.001), and Pmean (3.9 [3.6 – 4.1] vs. 5.7 [5.6 – 5.8] cmH₂O, P < 0.001).Conclusions: Changes in PIFR, Ppeak, and Pmean were associated with inspiratory time. PIFR and Ppeak values tended to decrease with increase in inspiratory time, while Pmean showed a contrasting trend. Increased inspiratory time in low-compliance cardiac arrest patients will help in reducing lung injury during adult CPR.

Effects of airway management and tidal volume feedback ventilation during pediatric resuscitation in piglets with asphyxial cardiac arrest

To compare the effect on the recovery of spontaneous circulation (ROSC) of early endotracheal intubation (ETI) versus bag-mask ventilation (BMV), and expiratory real-time tidal volume (VTe) feedback (TVF) ventilation versus without feedback or standard ventilation (SV) in a pediatric animal model of asphyxial cardiac arrest. Piglets were randomized into five groups: 1: ETI and TVF ventilation (10 ml/kg); 2: ETI and TVF (7 ml/kg); 3: ETI and SV; 4: BMV and TVF (10 ml/kg) and 5: BMV and SV. Thirty breaths-per-minute guided by metronome were given. ROSC, pCO2, pO2, EtCO2 and VTe were compared among groups. Seventy-nine piglets (11.3 ± 1.2 kg) were included. Twenty-six (32.9%) achieved ROSC. Survival was non-significantly higher in ETI (40.4%) than BMV groups (21.9%), p = 0.08. No differences in ROSC were found between TVF and SV groups (30.0% versus 34.7%, p = 0.67). ETI groups presented lower pCO2, and higher pO2, EtCO2 and VTe than BMV groups (p < 0.05). VTe was lower in TVF than in SV groups and in BMV than in ETI groups (p < 0.05). Groups 1 and 3 showed higher pO2 and lower pCO2 over time, although with hyperventilation values (pCO2 < 35 mmHg). ETI groups had non significantly higher survival rate than BMV groups. Compared to BMV groups, ETI groups achieved better oxygenation and ventilation parameters. VTe was lower in both TVF and BMV groups. Hyperventilation was observed in intubated animals with SV and with 10 ml/kg VTF.

Empirical evidence for safety of mechanical ventilation during simulated cardiopulmonary resuscitation on a physical model

BACKGROUND

Cardiac arrest is a critical event requiring adequate and timely response in order to increase a patient's chance of survival. In patients mechanically ventilated with advanced airways, cardiopulmonary resuscitation (CPR) maneuver may be simplified by keeping the ventilator on. This work assessed the response of an intensive care mechanical ventilator to CPR using a patient manikin ventilated in three conventional modes.

METHODS

Volume-controlled (VCV), pressure-controlled (PCV) and pressure regulated volume-controlled (PRVC) ventilation were applied in a thorax physical model, with or without chest compressions. The mechanical ventilator was set with inspiratory time of 1.0 s, ventilation rate of 10 breaths/min, positive end-expiratory pressure of 0 cmH₂O, FiO₂ of 1.0, target tidal volume of 600 mL and trigger level of -20 cmH₂O. Airway opening pressure and ventilatory flow signals were continuously recorded.

RESULTS

Chest compression resulted in increased airway peak pressure in all ventilation modes (p < 0.001), especially with VCV (137% in VCV, 83% in PCV, 80% in PRVC). However, these pressures were limited to levels similar to release valves in manual resuscitators (~60 cmH₂O). In pressure-controlled modes tidal/min volumes decreased (PRVC = 11%, p = 0.027 and PCV = 12%, p < 0.001), while still within the variability observed during bag-valve-mask ventilation. During VCV, variation in tidal/min volumes were not significant (p = 0.140). Respiratory rate did not change with chest compression.

CONCLUSIONS

Volume and pressure ventilation modes responded differently to chest compressions. Yet, variation in delivered volume and the measured peak pressures were within the reported for the standard bag-valve-mask system.

New volumetric capnography-derived parameter: a potentially valuable tool for detecting hyperventilation during cardiopulmonary resuscitation in a porcine model

Background

Volumetric capnography is increasingly being applied in cardiopulmonary resuscitation. However, during cardiopulmonary resuscitation, the abnormal ventilation state affects the monitoring effect of the most commonly used capnography-derived parameter, the partial carbon dioxide end-tidal pressure (PetCO₂). In this study, we evaluated the ability of a new volumetric capnography-derived parameter, the ratio between the PetCO₂ and the volume of carbon dioxide (CO₂) eliminated per min and per kilogram of body weight, for detecting hyperventilation during cardiopulmonary resuscitation.

Methods

We used 12 porcine models of primary ventricular fibrillation-induced cardiac arrest. Ventricular fibrillation was induced and left untreated for 4 min. Standardized chest compressions were performed throughout the experiment using mechanical cardiopulmonary resuscitation. Following 5 min of normal ventilation as a washout period, each animal underwent 4 types of ventilation. The main outcome measures were the PetCO₂, the ratio between the PetCO₂ and the volume of CO₂ eliminated per min and per kilogram of body weight with each ventilation type.

Results

Different ventilation types had a significant effect on the volumetric capnography-derived parameters. The PetCO₂ and ratio between the PetCO₂ and the volume of CO₂ eliminated per min and per kilogram of body weight values during cardiopulmonary resuscitation was significantly higher in non-hyperventilating than in hyperventilating animals. The ratio reflected hyperventilation accurately and immediately, with an area under the curve (AUC) of 0.98. The optimal cut-off point of the ratio for discriminating hyperventilation from non-hyperventilation was 6.36, with a sensitivity and specificity of 0.99 and 0.89, respectively.

Conclusions

The ratio between the PetCO₂ and the volume of CO₂ eliminated per min and per kilogram of body weight showed good performance in discriminating hyperventilation from non-hyperventilation and was sensitive to changes in ventilation status. This ratio may be a valuable clinical indicator for monitoring the ventilation status during cardiopulmonary resuscitation.

Longitudinal effect of high frequency training on CPR performance during simulated and actual pediatric cardiac arrest

Study aim

To determine the impact of high-frequency CPR training on performance during simulated and real pediatric CPR events in a pediatric emergency department (ED).

Methods

Prospective observational study. A high-frequency CPR training program (Resuscitation Quality Improvement (RQI)) was implemented among ED providers in a children's hospital. Data on CPR performance was collected longitundinally during quarterly retraining sessions; scores were analyzed between quarter 1 and quarter 4 by nonparametric methods. Data on CPR performance during actual patient events was collected by simultaneous combination of video review and compression monitor devices to allow measurement of CPR quality by individual providers; linear mixed effects models were used to analyze the association between RQI components and CPR quality.

Results

159 providers completed four consecutive RQI sessions. Scores for all CPR tasks during retraining sessions significantly improved during the study period. 28 actual CPR events were captured during the study period; 49 observations of RQI trained providers performing CPR on children were analyzed. A significant association was found between the number of prior RQI sessions and the percent of compressions meeting guidelines for rate (β coefficient -0.08; standard error 0.04; p = 0.03).

Conclusions

Over a 15 month period, RQI resulted in improved performance during training sessions for all skills. A significant association was found between number of sessions and adherence to compression rate guidelines during real patient events. Fewer than 30% of providers performed CPR on a patient during the study period. Multicenter studies over longer time periods should be undertaken to overcome the limitation of these rare events.

Modified volumetric capnography-derived parameter: A potentially stable indicator in monitoring cardiopulmonary resuscitation efficacy in a porcine model

AIM

We aimed to investigate whether the ability of the volumetric capnography-derived parameter, the volume of CO₂ eliminated per minute and per kg body weight (V'CO₂ kg^-1), in monitoring the quality of CPR and predicting the return of spontaneous circulation (ROSC) remains undisturbed by hyperventilation.

METHODS

This randomised crossover study included 12 male domestic pigs. After 4 min of untreated ventricular fibrillation, mechanical CPR was administered. Following 5-min washout periods, each animal underwent two sessions of experiments; four 5-min ventilation trials followed by advanced life support, consecutively in the two sessions.

RESULTS

Different ventilation types had no significant impact on V'CO₂ kg^-1 or haemodynamics. However, PETCO₂ was significantly affected by the ventilation type and coronary perfusion pressure (P < 0.05). The means ± standard deviations of PETCO₂ decreased linearly with an increase in the respiratory rate (RR) (P < 0.05). The PETCO₂ decreased from 20.42 ± 9.51 to 16.16 ± 5.07 (P < 0.05) as the tidal volume increased from 10 to 20 mL min^-1. No significant differences in V'CO₂ kg^-1 were observed between the three RR levels of ventilation types (P = 0.274). Post hoc analysis demonstrated a significant difference between the highest value of V'CO₂ kg^-1 in double tidal volume hyperventilation and normal ventilation and triple respiratory rate hyperventilation (P < 0.05). The AUC for V'CO₂ kg^-1 and PETCO₂ in discriminating between survivors and non-survivors was 0.80 and 0.71, respectively.

CONCLUSIONS

V'CO₂ kg^-1 performs better than PETCO₂ in monitoring the quality of CPR during hyperventilation. In predicting ROSC during variations in a ventilation state, V'CO₂ kg^-1 has good predictive ability.

Capnography during cardiac arrest

Successful resuscitation from cardiac arrest depends on provision of adequate blood flow to vital organs generated by cardiopulmonary resuscitation (CPR). Measurement of end-tidal expiratory pressure of carbon dioxide (ETCO₂) using capnography provides a noninvasive estimate of cardiac output and organ perfusion during cardiac arrest and can therefore be used to monitor the quality of CPR and predict return of spontaneous circulation (ROSC). In clinical observational studies, mean ETCO₂ levels in patients with ROSC are higher than those in patients with no ROSC. In prolonged out of hospital cardiac arrest, ETCO₂ levels <10 mmHg are consistently associated with a poor outcome, while levels above this threshold have been suggested as a criterion for considering patients for rescue extracorporeal resuscitation. An abrupt rise of ETCO₂ during CPR suggests that ROSC has occurred. Finally, detection of CO₂ in exhaled air following intubation is the most specific criterion for confirming endotracheal tube placement during CPR. The aetiology of cardiac arrest, variations in ventilation patterns during CPR, and the effects of drugs such as adrenaline or sodium bicarbonate administered as a bolus may significantly affect ETCO₂ levels and its clinical significance. While identifying ETCO₂ as a useful monitoring tool during resuscitation, current guidelines for advanced life support recommend against using ETCO₂ values in isolation for decision making in cardiac arrestmanagement.

Comparison of different inspiratory triggering settings in automated ventilators during cardiopulmonary resuscitation in a porcine model

BACKGROUND

Mechanical ventilation via automated in-hospital ventilators is quite common during cardiopulmonary resuscitation. It is not known whether different inspiratory triggering sensitivity settings of ordinary ventilators have different effects on actual ventilation, gas exchange and hemodynamics during resuscitation.

METHODS

18 pigs enrolled in this study were anaesthetized and intubated. Continuous chest compressions and mechanical ventilation (volume-controlled mode, 100% O2, respiratory rate 10/min, and tidal volumes 10ml/kg) were performed after 3 minutes of ventricular fibrillation. Group trig-4, trig-10 and trig-20 (six pigs each) were characterized by triggering sensitivities of 4, 10 and 20 (cmH2O for pressure-triggering and L/min for flow-triggering), respectively. Additionally, each pig in each group was mechanically ventilated using three types of inspiratory triggering (pressure-triggering, flow-triggering and turned-off triggering) of 5 minutes duration each, and each animal matched with one of six random assortments of the three different triggering settings. Blood gas samples, respiratory and hemodynamic parameters for each period were all collected and analyzed.

RESULTS

In each group, significantly lower actual respiratory rate, minute ventilation volume, mean airway pressure, arterial pH, PaO2, and higher end-tidal carbon dioxide, aortic blood pressure, coronary perfusion pressure, PaCO2 and venous oxygen saturation were observed in the ventilation periods with a turned-off triggering setting compared to those with pressure- or flow- triggering (all P<0.05), except when compared with pressure-triggering of 20 cmH2O (respiratory rate 10.5[10/11.3]/min vs 12.5[10.8/13.3]/min, P = 0.07; coronary perfusion pressure 30.3[24.5/31.6] mmHg vs 27.4[23.7/29] mmHg, P = 0.173; venous oxygen saturation 46.5[32/56.8]% vs 41.5[33.5/48.5]%, P = 0.575).

CONCLUSIONS

Ventilation with pressure- or flow-triggering tends to induce hyperventilation and deteriorating gas exchange and hemodynamics during CPR. A turned-off patient triggering or a pressure-triggering of 20 cmH2O is preferred for ventilation when an ordinary inpatient hospital ventilator is used during resuscitation.

Real-time tidal volume feedback guides optimal ventilation during simulated CPR

PURPOSE

We performed this study to investigate whether real-time tidal volume feedback increases optimal ventilation and decreases hyperventilation during manikin-simulated cardiopulmonary resuscitation (CPR).

BASIC PROCEDURES

We developed a new real-time tidal volume monitoring device (TVD) which estimated tidal volume in real time using a magnetic flowmeter. The TVD was validated with a volume-controlled mechanical ventilator with various tidal volumes. We conducted a randomized, crossover, manikin-simulation study in which 14 participants were randomly divided into a control (without tidal volume feedback, n = 7) and a TVD group (with real-time tidal volume feedback, n = 7) and underwent manikin simulation. The optimal ventilation was defined as 420-490 mL of tidal volumes for a 70-kg adult manikin. After 2 weeks of the washout period, the simulation was repeated via the participants' crossover.

MAIN FINDINGS

In the validation study, 97.6% and 100% of the difference ratios in tidal volumes between the mechanical ventilator and TVD were within ±1.5% and ±2.5%, respectively. During manikin-simulated CPR, TVD use increased the proportion of optimal ventilation per person. Its median values (range) of the control group and the TVD group were 37.5% (0.0-65.0) and 87.5% (65.0-100.0), respectively, P < .001). TVD use also decreased hyperventilation. The proportions of hyperventilation in the control group and the TVD group were 25.0% vs 8.9%, respectively (P < .001).

PRINCIPAL CONCLUSIONS

Real-time tidal volume feedback using the new TVD guided the rescuers to provide optimal ventilation and to avoid hyperventilation during manikin-simulated CPR.

Tracheal intubation during pediatric cardiopulmonary resuscitation: A videography-based assessment in an emergency department resuscitation room

OBJECTIVES

To describe procedural characteristics of tracheal intubation (TI) during cardiopulmonary resuscitation (CPR) in a pediatric emergency department, and to characterize interruptions in CPR associated with TI performance.

METHODS

Retrospective single center case series. Resuscitations in a pediatric ED are videorecorded for quality improvement. Children who underwent TI while receiving chest compressions were eligible for inclusion. Intubations done by methods other than direct laryngoscopy were excluded. Background data included patient age and training background of intubator. Data on intubation attempts (success, laryngoscopy time) and chest compressions (interruptions, duration of pauses) were collected.

RESULTS

Between December 2012 and February 2014, 32 patients had 59 TI attempts performed during CPR. Overall first attempt success at TI was 15/32 (47%); a median of 2 attempts were made per patient (range 1 to 4). Median laryngoscopy time was 47s (range 8-115s). 32/59 (54%) TI attempts had an associated interruption in CPR; the median interruption duration was 25s (range 3-64s). TI attempts without interruption in CPR were successful in 20/32 (63%) compared to 11/27 (41%) when CPR was paused (p=0.09). Laryngoscopy time was not significantly different between TI attempts with (47±21s) and without (47±26s; p=0.2) interruptions in compressions. 25/32 (78%) of pauses exceeded 10s in duration.

CONCLUSIONS

TI during pediatric CPR results in significant interruptions in chest compressions. Procedural outcomes were not significantly different between attempts with and without compressions paused. In children receiving CPR, TI should be performed without pausing chest compressions.

A comparison of video review and feedback device measurement of chest compressions quality during pediatric cardiopulmonary resuscitation

AIM

To describe chest compression (CC) rate, depth, and leaning during pediatric cardiopulmonary resuscitation (CPR) as measured by two simultaneous methods, and to assess the accuracy and reliability of video review in measuring CC quality.

METHODS

Resuscitations in a pediatric emergency department are videorecorded for quality improvement. Patients aged 8-18 years receiving CPR under videorecording were eligible for inclusion. CPR was recorded by a pressure/accelerometer feedback device and tabulated in 30-s epochs of uninterrupted CC. Investigators reviewed videorecorded CPR and measured rate, depth, and release by observation. Raters categorized epochs as 'meeting criteria' if 80% of CCs in an epoch were done with appropriate depth (>45 mm) and/or release (<2.5 kg leaning). Comparison between device measurement and video was made by Spearman's ρ for rate and by κ statistic for depth and release. Interrater reliability for depth and release was measured by κ statistic.

RESULTS

Five patients underwent videorecorded CPR using the feedback device. 97 30-s epochs of CCs were analyzed. CCs met criteria for rate in 74/97 (76%) of epochs; depth in 38/97 (39%); release in 82/97 (84%). Agreement between video and feedback device for rate was good (ρ = 0.77); agreement was poor for depth and release (κ 0.04-0.41). Interrater reliability for depth and release measured by video was poor (κ 0.04-0.49).

CONCLUSION

Video review measured CC rate accurately; depth and release were not reliably or accurately assessed by video. Future research should focus on the optimal combination of methods for measuring CPR quality.

Videographic assessment of cardiopulmonary resuscitation quality in the pediatric emergency department

OBJECTIVE

To describe the adherence to guidelines for CPR in a tertiary pediatric emergency department (ED) where resuscitations are reviewed by videorecording.

METHODS

Resuscitations in a tertiary pediatric ED are videorecorded as part of a quality improvement project. Patients receiving CPR under videorecorded conditions were eligible for inclusion. CPR parameters were quantified by retrospective review. Data were described by 30-s epoch (compression rate, ventilation rate, compression:ventilation ratio), by segment (duration of single providers' compressions) and by overall event (compression fraction). Duration of interruptions in compressions was measured; tasks completed during pauses were tabulated.

RESULTS

33 children received CPR under videorecorded conditions. A total of 650 min of CPR were analyzed. Chest compressions were performed at <100/min in 90/714 (13%) of epochs; 100-120/min in 309/714 (43%); >120/min in 315/714 (44%). Ventilations were 6-12 breaths/min in 201/708 (23%) of epochs and >12/min in 489/708 (70%). During CPR without an artificial airway, compression:ventilation coordination (15:2) was done in 93/234 (40%) of epochs. 178 pauses in CPR occurred; 120 (67%) were <10s in duration. Of 370 segments of compressions by individual providers, 282/370 (76%) were <2 min in duration. Median compression fraction was 91% (range 88-100%).

CONCLUSIONS

CPR in a tertiary pediatric ED frequently met recommended parameters for compression rate, pause duration, and compression fraction. Hyperventilation and failure of C:V coordination were very common. Future studies should focus on the impact of training methods on CPR performance as documented by videorecording.

Preventing and Treating Hypoxia: Using a Physiology Simulator to Demonstrate the Value of Pre-Oxygenation and the Futility of Hyperventilation

INTRODUCTION

Insufficient pre-oxygenation before emergency intubation, and hyperventilation after intubation are mistakes that are frequently observed in and outside the operating room, in clinical practice and in simulation exercises. Physiological parameters, as appearing on standard patient monitors, do not alert to the deleterious effects of low oxygen saturation on coronary perfusion, or that of low carbon dioxide concentrations on cerebral perfusion. We suggest the use of HumMod, a computer-based human physiology simulator, to demonstrate beneficial physiological responses to pre-oxygenation and the futility of excessive minute ventilation after intubation.

METHODS

We programmed HumMod, to A.) compare varying times (0-7 minutes) of pre-oxygenation on oxygen saturation (SpO2) during subsequent apnoea; B.) simulate hyperventilation after apnoea. We compared the effect of different minute ventilation rates on SpO2, acid-base status, cerebral perfusion and other haemodynamic parameters.

RESULTS

A.) With no pre-oxygenation, starting SpO2 dropped from 98% to 90% in 52 seconds with apnoea. At the other extreme, following full pre-oxygenation with 100% O2 for 3 minutes or more, the SpO2 remained 100% for 7.75 minutes during apnoea, and dropped to 90% after another 75 seconds. B.) Hyperventilation, did not result in more rapid normalization of SpO2, irrespective of the level of minute ventilation. However, hyperventilation did cause significant decreases in cerebral blood flow (CBF).

CONCLUSIONS

HumMod accurately simulates the physiological responses compared to published human studies of pre-oxygenation and varying post intubation minute ventilations, and it can be used over wider ranges of parameters than available in human studies and therefore available in the literature.