Abstract 4147521: Use of an ETCO ₂ -Directed Resuscitation Algorithm in a Pediatric Swine Model of Asphyxial Cardiac Arrest

Introduction: Current pediatric cardiopulmonary resuscitation (CPR) guidelines provide uniform recommendations for resuscitative efforts, including chest compression rate (CCR), chest compression depth, and epinephrine administration interval (EAI), despite differences in cardiac arrest etiologies or in the patient’s response to resuscitative efforts. Titration of the CCR or the EAI based on the patient’s physiologic response to resuscitation could individualize and optimize resuscitative efforts. Our research group has previously found that use of an end-tidal carbon dioxide (ETCO 2 )-directed algorithm to titrate the CCR and EAI improved intra-arrest hemodynamics and short-term survival in a swine model. Research Question: Here, we investigated whether the use of this ETCO 2 -directed resuscitation algorithm improved long-term survival and neuropathologic outcomes in a similar swine model of cardiac arrest. Methods: We performed 46 resuscitations in 4-5 kg swine. Pigs underwent 7 minutes of asphyxia, 30 seconds of ventricular fibrillation, and 10 minutes of resuscitation prior to the first defibrillation. Pigs were randomized to standard CPR or ETCO 2 -directed algorithm CPR. A sham group was also studied. In the standard group, chest compressions were performed at 100 compressions/minute and epinephrine was administered every 4 minutes per standard pediatric guidelines. In the algorithm group, the CCR was increased by 10 compressions/minute for every minute that the ETCO 2 was <30 torr and the EAI was increased up to every two minutes. Pigs that achieved return of spontaneous circulation (ROSC) were extubated and survived 3 days. Daily neurobehavioral assessments were performed. In blinded fashion, viable and ischemic neurons were counted in the basal ganglia. Results: The rate of ROSC was similar in the standard (10/24, 42%) and algorithm (10/22, 46%, p >0.99) groups. The rate of 3-day survival was also similar between the two groups (4/24 [17%] in the standard group and 6/22 [27%] in the algorithm group, p =0.48). The standard and algorithm groups both had fewer viable neurons and more ischemic neurons in putamen than shams ( p <0.01 for all pairwise comparisons, Figure 1). The number of viable and ischemic neurons were similar between the two CPR groups. Conclusion: In this model of pediatric asphyxial cardiac arrest, use of an ETCO 2 -directed resuscitation algorithm did not improve the rate of ROSC, 3-day survival, or neuropathologic injury in the basal ganglia.