Abstract 17: Combined Intra- and Post-Cardiac Arrest Therapeutic Hypothermia Improves Survival and Neurologic Outcome Compared to Either Therapy Alone
Background: Post-cardiac arrest therapeutic hypothermia (TH) improves outcomes in comatose cardiac arrest survivors. However, inadequate understanding of the mechanisms and therapeutic windows remains a barrier to optimization. Both short duration intra-arrest cooling and long duration post-arrest cooling are effective in animal models, suggesting distinct mechanisms of protection with different therapeutic windows. In this study, we tested the hypothesis that combined intra- and post-cardiac arrest TH has an additive or synergistic therapeutic benefit when compared to either therapy alone.
Methods: Male Long Evans rats were subjected to a standard 8-minute asphxial cardiac arrest model. Rats were block randomized to one of 4 treatment groups; 1) intraarrest TH (IA), 2) post-arrest TH (PA), 3) combined intra- and post-arrest TH (IA+PA), or 4) normothermia (N) (n=12/group). TH was induced using nasopharyngeal cooling with 100 ml/kg/min iced saline. IA cooling was initiated at the start or CPR and TH maintained for 1 hour after return of spontaneous circulation (ROSC). PA cooling was initiated 1 hour after ROSC and maintained for 24 hours. Target temperature was set at 32-34°C, and monitored by intracranial temperature probe during nasopharyngeal cooling and intraperitoneal telemetric temperature probe for long-term post-arrest cooling. Post-arrest neurologic function score (NFS=0-500) was measured daily. Rats surviving 72 hours were euthanized by perfusion fixation and brains processed future histological analysis. Proportional outcomes were compared using a Fisher’s exact test and significance set at a one-tailed p≤.0.05.
Results: Brain target temperature was achieved 7.8 ± 3.3 min after initiation of IA cooling, and 5.3 ± 1.7 min after initiation of PA cooling. Survival was 42% (5/12), 50% (6/12), 50% (6/12), and 92% (11/12) in the N, IA, PA, and IA+PA groups respectively (p ≤0.05 IA+PA vs. all other groups). Survival with good neurologic function (NFS ≥450) was 33% (4/12) in the IA+PA group and 0% (01/12) for all other treatment groups (p≤0.05 IA+PA vs. all other groups).
Conclusion: This result supports our hypothesis that combined intra- and post-cardiac arrest TH has additive or synergistic benefits in the treatment of cardiac arrest.
- Cardiopulmonary resuscitation
- Post cardiac arrest care
- Post cardiac resuscitation
- © 2013 by American Heart Association, Inc.