Abstract 82: Preserved Heart Rate Variability During Rapid Head Cooling Correlated to Better Survival and Neurological Outcomes in a Pig Model of Cardiac Arrest
Background: Rapid head cooling initiated with CPR improves survival and neurological outcomes after prolonged cardiac arrest. However, the effects of head cooling on cardiac electrical activity after resuscitation are still unknown. In the current study, we investigated the effects of therapeutic hypothermia on the short-term heart rate variability (HRV).
Methods: After 10 mins of untreated ventricular fibrillation, sixteen pigs, 39–45 kg, were randomized to hypothermia (n=8) or control (n=8). For the hypothermia group, intra-nasal induced head cooling was initiated with CPR and persisted for 4 hrs after resuscitation. After 5 mins of mechanical chest compression, a 150 Joule biphasic electrical shock was delivered. Short term HRV analysis, including SDNN (standard deviation of normal to normal intervals), RMSSD (square root of the mean squared differences of successive normal to normal intervals), and HRV triangular index, were compared and correlated to the 96 hr neurological outcomes.
Results: Eight animals in hypothermia group and seven animals in the control group were successfully resuscitated. All 8 hypothermic but only 2 of the control animals survived to 96 hrs. The 96 hr neurological deficit scores of the hypothermic group wase significantly lower than control group (0 vs. 400, P=0.005). All the investigated HRV indices were significantly higher in the hypothermic group 3 hrs after resuscitation as compared to the control group (Table). A significant correlation between HRV and neurological outcomes were also observed in the hypothermia group (r=−0.61, p=0.016).
Conclusion: The preserved HRV during rapid head cooling after resuscitation was associated with better survival and neurological outcomes in this pig model of long term cardiac arrest.
- © 2010 by American Heart Association, Inc.