Abstract 14213: Injury Characteristics of Chest Compressions in a Swine Model of Infant Asphyxial Cardiac Arrest Using Either 1.5 inch or 1/3 Anterior-Posterior Diameter Depth Targets

Abstract

Background: Current AHA guidelines for the delivery of chest compressions (CC) for infants and children are largely consensus based, and recommended depths of 1.5 inches or 1/3 anterior-posterior chest diameter (APD). It is unclear whether these have equal potential for injury. Objectives: We sought to examine and compare injury characteristics of CC delivered at 1.5 inches or 1/3 APD in an infant-sized model of asphyxial OHCA. Methods: Thirty-six juvenile swine weighing 10.6kg +/- 0.84 (approximating the 50 th percentile for a 12-month-old) were anesthetized, paralyzed, intubated, and mechanically ventilated (FiO2 21%). APD was measured and by two investigators via a sliding T-square. After instrumentation, the endotracheal tube was manually occluded to induce asphyxia, and occlusion was maintained for 9 minutes. Animals with an organized rhythm after 8 minutes 45 seconds of asphyxia received a single, 3-second transthoracic shock to induce ventricular fibrillation. At 9 minutes, each was then randomized to receive CC with a depth of 1.5 inches (Group 1) or 1/3 APD (Group 2), both with a rate of 100 per minute. ALS drugs were administered after 13 minutes, followed by initial defibrillation attempt at 14 minutes. Resuscitation continued until return of spontaneous circulation (ROSC) or 20 minutes of failed resuscitation. Survivors were sacrificed with KCl after 20 minutes of observation. Veterinary staff blinded to group assignment conducted necropsies to assess lung injury, rib fracture, hemothorax, airway bleeding, great vessel dissection, and heart/liver/spleen contusion. Characteristics were compared via Chi-Squared test or Mann-Whitney U-test using an alpha = 0.05. Results: Group 1 had n=18 and Group 2 had n=18 animals. Mean (SD) APD overall was 5.58 (0.22) inches, yielding a mean 1/3 APD depth of 1.86 inches. APD did not differ between groups. ROSC rates did not differ between groups (Group 1: 66.7% vs Group 2: 83.33%; p = 0.248. No injury characteristics differed significantly between groups. Airway bleeding rates were noteworthy though not different between groups (Group 1: 18.8% vs Group 2: 42.1%; p = 0.219). Conclusions: In a swine model of infant OHCA and resuscitation, both CC depth strategies had similar injury characteristics.