Abstract 215: Hyperoxic versus Normoxic Resuscitation in Pediatric Asphyxial Cardiac Arrest: Effects on Hemodynamics, Mortality and Functional Outcome.
Current AHA guidelines recommend the use of 100% O2 during resuscitation and for an undefined period thereafter in pediatric cardiac arrest (CA). Studies in adult canine ventricular fibrillation models suggested a reduction of neuronal damage and no deleterious hemodynamic effects of room air resuscitation. Unlike adults, asphyxia is the principal cause of CA in children. There currently exist no comparable studies in pediatric models of CA. We used an age appropriate rodent model of asphyxial CA (ACA) to simulate this condition. We hypothesized that resuscitation with 100% O2 will produce favorable effects on hemodynamics, mortality and functional outcome after ACA in juvenile rats. Anesthetized 16–18 days old rats underwent ACA for 9 min. During resuscitation, rats were randomized and ventilated with hyperoxia (100% O2, n=10), normoxia (21% O2, n=10), and goal directed (GD) O2 to maintain >90% O2 saturation (pulse-oximetry) (n=10). Two sham groups (100% O2, n=6) and (21% O2, n=5) were used as controls. Hemodynamic parameters were recorded at baseline, 10, 30 and 60 min after ACA. Motor function [beam balance (BB), and inclined plane (IP) tests] was assessed on d1-5 and spatial memory (Morris Water Maze task) was assessed on d7-14. Statistical significance was tested by 1-way ANOVA (for hemodynamic parameters) and 2-way RM-ANOVA (for functional outcome). No significant differences in pre-arrest values for arterial pCO2, pH, HR and mean arterial pressure (MAP) were noted. Rats ventilated with 21% vs 100% vs GD O2 for the 1st h after resuscitation exhibited higher HR (413.8±8.4, 342.2±4.3, 366.7±4.2 respectively, p<0.05), lower MAP (36.3±3.2, 48.3±1.2, 46±1.4 respectively, p<0.05) and lower pO2 (55.2±3.6, 361.9±10.7, 73±5.7 respectively, p<0.05). 72h mortality was 31%, 17% and 26% in the 21%, 100% and GD O2 groups respectively. Latency in BB task was significantly prolonged in the 21%, 100% and GD O2 groups vs Sham. Rats resuscitated with 100% O2 spent significantly more time in the target quadrant vs 21% O2 group during probe trial. Surprisingly, normoxic resuscitation after ACA is associated with higher mortality and hypotension. 100% O2 resuscitation does not improve motor testing after ACA however, it might play a role in spatial reference memory formation.
- © 2010 by American Heart Association, Inc.