Effects of sustained inflation pressure during neonatal cardiopulmonary resuscitation of asphyxiated piglets

Chest compressions superimposed with sustained inflation during neonatal cardiopulmonary resuscitation: are we ready for a clinical trial?

Neonates requiring cardiopulmonary resuscitation (CPR) are at risk of mortality and neurodevelopmental injury. Poor outcomes following the need for chest compressions (CCs) in the delivery room prompt the critical need for improvements in resuscitation strategies. This article explores a technique of CPR which involves CCs with sustained inflation (CC+SI). Unique features of CC+SI include (1) improved tidal volume delivery, (2) passive ventilation during compressions, (3) uninterrupted compressions and (4) improved stability of cerebral blood flow during resuscitation. CC+SI has been shown in animal studies to have improved time to return of spontaneous circulation and reduced mortality without significant increase in markers of inflammation and injury in the lung and brain, compared with standard CPR. The mechanics of CCs, rate of compressions, ventilation strategies and compression-to-ventilation ratios are detailed here. A large randomised controlled trial comparing CC+SI versus the current 3:1 compression-to-ventilation ratio is needed, given the growing evidence of its potential benefits.

Chest compressions superimposed with sustained inflations during cardiopulmonary resuscitation in asphyxiated pediatric piglets

BACKGROUND

Pediatric resuscitation guidelines recommend continuous chest compression with asynchronized ventilation (CCaV) during cardiopulmonary resuscitation. We recently described that providing a constant high distending pressure, or sustained inflation (SI) while performing continuous chest compressions (CC = CC + SI) reduces time to return of spontaneous circulation (ROSC) in neonatal and pediatric piglets with asphyxia-induced cardiac arrest.

METHODS

To determine if CC + SI compared to CCaV will improve frequency of achieving ROSC and reduce time to ROSC in asphyxiated pediatric piglets. Twenty-eight pediatric piglets (21-24 days old) were anesthetized and asphyxiated by clamping the endotracheal tube. Piglets were randomized to CC + SI or CCaV for resuscitation (n = 14/group). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.

RESULTS

The mean(SD) duration of resuscitation was significantly reduced with CC + SI compared to CCaV with 208(190) vs. 388(258)s, p = 0.045, respectively. The number of piglets achieving ROSC with CC + SI and CCaV were 12/14 vs. 6/14, p = 0.046. Minute ventilation, end-tidal carbon dioxide, ventilation rate, and positive end expiratory pressures were also significantly improved with CC + SI.

CONCLUSIONS

CC + SI improves duration of resuscitation and increases number of piglets achieving ROSC secondary to improved minute ventilation.

IMPACT

Chest compressions superimposed with sustained inflation resulted in shorter duration of resuscitation Chest compressions superimposed with sustained inflation resulted in higher number of piglets achieving return of spontaneous circulation Further animal studies are needed to examine chest compressions superimposed with sustained inflation.

Chest compression rates of 60/min versus 90/min during neonatal cardiopulmonary resuscitation: a randomized controlled animal trial

Background

To compare chest compression (CC) rates of 60/min with 90/min and their effect on the time to return of spontaneous circulation (ROSC), survival, hemodynamic, and respiratory parameters. We hypothesized that asphyxiated newborn piglets that received CC at 60/min vs. 90/min during cardiopulmonary resuscitation would have a shorter time to ROSC.

Methods

Newborn piglets (n = 7/group) were anesthetized, tracheotomized and intubated, instrumented and exposed to 45 min normocapnic hypoxia followed by asphyxia and cardiac arrest. Piglets were randomly allocated to a CC rate of 60/min or 90/min. CC was performed using an automated CC machine using CC superimposed with sustained inflation. Hemodynamic parameters, respiratory parameters, and applied compression force were continuously measured.

Results

The mean (IQR) time to ROSC was 97 (65-149) s and 136 (88-395) s for CC rates of 60/min and 90/min, respectively (p = 0.31). The number of piglets that achieved ROSC was 5 (71%) and 5 (71%) with 60/min and 90/min CC rates, respectively (p = 1.00). Hemodynamic parameters (i.e., diastolic and mean blood pressure, carotid blood flow, stroke volume, end-diastolic volume, left ventricular contractile function) and respiratory parameters (i.e., minute ventilation, peak inflation and peak expiration flow) were all similar with a CC rate of 60/min compared to 90/min.

Conclusion

Time to ROSC, hemodynamic, and respiratory parameters were not significantly different between CC rates of 60/min vs. 90/min. Different CC rates during neonatal resuscitation warrant further investigation.

Assessment of optimal chest compression depth during neonatal cardiopulmonary resuscitation: a randomised controlled animal trial

AIM

The study aimed to examine the optimal anterior-posterior depth which will reduce the time to return of spontaneous circulation and improve survival during chest compressions. Asphyxiated neonatal piglets receiving chest compression resuscitated with a 40% anterior-posterior chest depth compared with 33%, 25% or 12.5% will have reduced time to return of spontaneous circulation and improved survival.

METHODS

Newborn piglets (n=8 per group) were anaesthetised, intubated, instrumented and exposed to 45 min normocapnic hypoxia followed by asphyxia and cardiac arrest. Piglets were randomly allocated to four intervention groups ('anterior-posterior 12.5% depth', 'anterior-posterior 25% depth', 'anterior-posterior 33% depth' or 'anterior-posterior 40% depth'). Chest compressions were performed using an automated chest compression machine with a rate of 90 per minute. Haemodynamic and respiratory parameters, applied compression force, and chest compression depth were continuously measured.

RESULTS

The median (IQR) time to return of spontaneous circulation was 600 (600-600) s, 135 (90-589) s, 85 (71-158)* s and 116 (63-173)* s for the 12.5%, 25%, 33% and 40% depth groups, respectively (*p<0.001 vs 12.5%). The number of piglets that achieved return of spontaneous circulation was 0 (0%), 6 (75%), 7 (88%) and 7 (88%) in the 12.5%, 25%, 33% and 40% anterior-posterior depth groups, respectively. Arterial blood pressure, central venous pressure, carotid blood flow, applied compression force, tidal volume and minute ventilation increased with greater anterior-posterior chest depth during chest compression.

CONCLUSIONS

Time to return of spontaneous circulation and survival were similar between 25%, 33% and 40% anterior-posterior depths, while 12.5% anterior-posterior depth did not result in return of spontaneous circulation or survival. Haemodynamic and respiratory parameters improved with increasing anterior-posterior depth, suggesting improved organ perfusion and oxygen delivery with 33%-40% anterior-posterior depth.

TRIAL REGISTRATION NUMBER

PTCE0000193.

Sustained Inflation During Chest Compression: A New Technique of Pediatric Cardiopulmonary Resuscitation That Improves Recovery and Survival in a Pediatric Porcine Model

Background

Chest compression (CC) during sustained inflations (CC+SI) compared with CC with asynchronized ventilation (CCaV) during cardiopulmonary resuscitation in asphyxiated pediatric piglets will reduce time to return of spontaneous circulation (ROSC).

Methods and Results

Piglets (20–23 days of age, weighing 6.2–10.2 kg) were anesthetized, intubated, instrumented, and exposed to asphyxia. Cardiac arrest was defined as mean arterial blood pressure <25 mm Hg with bradycardia. After cardiac arrest, piglets were randomized to CC+SI (n=12) or CCaV (n=12) or sham (n=8). Sham‐operated animals had no asphyxia. Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded. There were no differences in baseline parameters or the duration and degree of asphyxiation. Median (interquartile range) Time to ROSC was 248 (41–346) seconds compared with 720 (167–720) seconds in the CC+SI group and CCaV group, respectively (P=0.0292). There was a 100% higher rate of ROSC in the CC+SI group versus CCaV group, with 10 (83%) versus 5 (42%) achieving ROSC (P=0.089), respectively. Piglets in the CC+SI and CCaV groups received intravenous epinephrine boluses to achieve ROSC (8/12 versus 10/12 P=0.639). There was a significantly higher minute ventilation in the CC+SI group, which was secondary to a 5‐fold increase in the number of inflations per minute and a 1.5‐fold increase in tidal volume.

Conclusions

CC+SI reduced time to ROSC and improved survival compared with using CCaV. CC+SI allowed passive ventilation of the lung while providing chest compressions. This technique warrants further studies to examine the potential to improve outcomes in pediatric patients with cardiac arrest.

Registration

URL: https://www.preclinicaltrials.eu; Unique identifier: PCTE0000152.

Is Chest Compression Superimposed with Sustained Inflation during Cardiopulmonary Resuscitation an Alternative to 3:1 Compression to Ventilation Ratio in Newborn Infants?

Approximately 0.1% for term and 10-15% of preterm infants receive chest compression (CC) in the delivery room, with high incidence of mortality and neurologic impairment. The poor prognosis associated with receiving CC in the delivery room has raised concerns as to whether specifically-tailored cardiopulmonary resuscitation methods are needed. The current neonatal resuscitation guidelines recommend a 3:1 compression:ventilation ratio; however, the most effective approach to deliver chest compression is unknown. We recently demonstrated that providing continuous chest compression superimposed with a high distending pressure or sustained inflation significantly reduced time to return of spontaneous circulation and mortality while improving respiratory and cardiovascular parameters in asphyxiated piglet and newborn infants. This review summarizes the current available evidence of continuous chest compression superimposed with a sustained inflation.

Return of Spontaneous Circulation Depends on Cardiac Rhythm During Neonatal Cardiac Arrest in Asphyxiated Newborn Animals

Objective: Pulseless electrical activity (PEA) occurs in asphyxiated newborn piglets and infants. We aimed to examine whether different cardiac rhythms (asystole, bradycardia, PEA) affects the resuscitation outcomes during continuous chest compressions (CC) during sustained inflations (CC+SI). Design: This study is a secondary analysis of four previous randomized controlled animal trials that compared CC+SI with different CC rate (90 or 120/min), SI duration (20 or 60 s), peak inflation pressure (10, 20, or 30 cmH₂O), and oxygen concentration (18, 21, or 100%). Setting and Subjects: Sixty-six newborn mixed breed piglets (1-3 days of age, weight 1.7-2.4 kg) were obtained on the day of experimentation from the University Swine Research Technology Center. Interventions: In all four studies, piglets were randomized into intervention or sham. Piglets randomized to "intervention" underwent both hypoxia and asphyxia, whereas, piglets randomized to "sham" received the same surgical protocol, stabilization, and equivalent experimental periods without hypoxia and asphyxia. Measurements: To compare differences in asphyxiation time, time to return of spontaneous circulation (ROSC), hemodynamics, and survival rate in newborn piglets with asystole, bradycardia or PEA. Main Results: Piglets with PEA (n = 29) and asystole (n = 13) had a significantly longer asphyxiation time and time to ROSC vs. bradycardia (n = 24). Survival rates were similar between all groups. Compared to their baseline, mean arterial pressure and carotid blood flow were significantly lower 4 h after resuscitation in all groups, while being significantly higher in the bradycardia group. Conclusion: This study indicates that cardiac rhythm before resuscitation influences the time to ROSC and hemodynamic recovery after ROSC.

Sustained inflation with 21% versus 100% oxygen during cardiopulmonary resuscitation of asphyxiated newborn piglets - A randomized controlled animal study

BACKGROUND

Current neonatal resuscitation guidelines recommend using 100% oxygen during chest compressions (CC), however the most effective oxygen concentration during cardiopulmonary resuscitation remains controversial.

AIM

In term newborn piglets with asphyxia-induced cardiac arrest does 21% oxygen compared to 100% oxygen during resuscitation using CC during sustained inflation (SI; CC + SI) will have a reduced time to return of spontaneous circulation (ROSC).

INTERVENTION AND MEASUREMENTS

Twenty-two mixed breed piglets (1-3 days old, 1.7-2.4 kg), were obtained on the day of the experiment and anesthetized, intubated, instrumented, and exposed to 30-min normocapnic hypoxia followed by asphyxia. Piglets were resuscitated using CC + SI and randomized to 21% oxygen (n = 8) or 100% oxygen (n = 8). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.

MAIN RESULTS

Baseline parameters were similar between 21% and 100% oxygen groups. There was no difference in asphyxiation (duration and degree) between groups. Time to ROSC was similar between 21% and 100% oxygen groups: median (interquartile range - IQR) 80 (70-190)sec vs. 90 (70-324)sec, (p = 0.56). There was no significant difference in the rate of ROSC between 21% and 100% oxygen groups: 7/8 (88%) vs. 5/8 (63%), (p = 0.569). All piglets that achieved ROSC survived to four hours post-resuscitation. Hemodynamics and regional perfusion were not significantly different between groups.

CONCLUSIONS

In term newborn piglets resuscitated by CC + SI, the use of 21% oxygen resulted in a similar time to ROSC, short-term survival, and hemodynamic recovery compared to 100% oxygen.

Asphyxiated Female and Male Newborn Piglets Have Similar Outcomes With Different Cardiopulmonary Resuscitation Interventions

Background: Male newborns have a greater risk of poor cardiovascular and respiratory outcomes compared to females. The mechanisms associated with the "male disadvantage" remains unclear. We have previously shown no difference between male and female newborn piglets during hypoxia, asphyxia, resuscitation, and post-resuscitation recovery. However, it is unknown if there are differences in resuscitation outcomes between males and females during different cardiopulmonary resuscitation techniques. Intervention and Measurements: Secondary analysis of 184 term newborn mixed breed duroc piglets (1-3 days of age, weighing 2.0 (0.2) kg) from seven different studies, which were exposed to 30-50 min of normocapnic hypoxia followed by asphyxia until asystole. This was followed by cardiopulmonary resuscitation. For the analysis, piglets were divided into male and female groups, as well as resuscitation technique groups (sustained inflation, 3:1 compression-to-ventilation ratio, or asynchronous ventilations during chest compressions). Cardiac function, carotid blood flow, and cerebral oxygenation were continuously recorded throughout the experiment. Main results: Regardless of resuscitation technique, there was no significant difference between males and females in the number achieving return of spontaneous circulation (ROSC) [95/123 (77%) vs. 48/61 (79%)], the time to achieve ROSC [112 (80-185) s vs. 110 (77-186) s], and the 4-h survival rate [81/95 (85%) vs. 40/48 (83%)]. Levels of the injury markers interleukin (IL)-1ß, IL-6, IL-8, and tumor necrosis factor-α in frontoparietal cortex tissue homogenates were similar between males and females. Conclusions: Regardless of resuscitation technique, there was no significant effect of sex on resuscitation outcome, survival, and hemodynamic recovery in asphyxiated newborn piglets.