Abstract 2461: Therapeutic Hypothermia During CPR Reduces Myocardial Ischemic Injury
Therapeutic hypothermia following return of spontaneous circulation (ROSC) improves neurological outcome and survival. In the present study, we examined the effects of therapeutic hypothermia initiated during cardiac resuscitation on the severity of global myocardial ischemic injury. We hypothesized that therapeutic hypothermia decreases myocardial ischemic injury and thereby further improves the outcomes of CPR. Ventricular fibrillation (VF) was induced and untreated in 10 S-D rats, weighing between 450–550g, randomized into 2 groups: normothermia or induced hypothermia. CPR was started 8 minutes after onset of VF. Hypothermia was initiated coincident with the start of CPR. The blood temperature was reduced and maintained at 32°C±0.2 with a cooling blanket and continued for 4 hours after ROSC. The normothermia group was maintained at 37°C±0.2. Precordial compression was adjusted to achieve coronary perfusion pressure to 22±2 mm Hg. Defibrillation was attempted after 8 minutes of CPR. Significantly better echocardiographically measured cardiac output (CO) and myocardial performance index (MPI) were observed in the hypothermia group. The magnitude of ST segment elevation and the incidence of recurrent VF (8±6 vs 0.6±0.5, p<0.05) were significantly reduced in comparison with normothermic animals and resulted in significantly higher 7 day survival rates (1/5 vs 5/5, p<0.01). We conclude that therapeutic hypothermia initiated during cardiac arrest and CPR also reduced myocardial ischemic injury and thereby contributed to improved survival.