Abstract P200: Impact of Duration of Cooling in Mild Therapeutic Hypothermia on Comatose Survivors of Cardiac Arrest: J-PULSE-Hypo registry
Introduction: Mild therapeutic hypothermia (MTH) has neuroprotective effect and provides improved survival and neurological outcome on comatose survivors of out-of-hospital cardiac arrest. But it is still unclear the optimal duration of cooling in MTH.
Hypothesis: We assessed the hypothesis that longer duration of cooling provide better neurologic outcome on comatose survivors of cardiac arrest treated with MTH.
Methods: We conducted a multicenter retrospective study at 12 institutions to evaluate the efficacy of MTH on comatose survivors of out-of-hospital cardiac arrest treated with MTH between 2005 and 2008. Duration of cooling was recorded in 251 patients. Patients were divided into 2 groups according to duration of cooling of <36 hours (Group-A, N=150) or ≥36 hours (Group-B, N=101). We assessed 30-day survival, 30-day favorable neurological finding, and complications. A favorable neurological finding was defined as a cerebral Pittsburgh performance category of 1 or 2.
Results: Time interval from collapse to return of spontaneous circulation (ROSC) was significantly longer in Group-A than in Group-B (median 18 min vs 22 min, P=0.04). There were no significant difference in the rate of 30-day survival (83% vs 84%, P=0.74) and 30-day favorable neurological finding (60% vs 55%, P=0.47) between Group-A and Group-B. Complications occurred more frequently in Group-A than in Group-B (19% vs 41%, P<0.01). Because baseline severity of patients (time interval from collapse to ROSC) was different between 2 groups, we provide additional analysis in patients with prolonged resuscitation (time interval from collapse to ROSC ≥30 min). In patients with prolonged resuscitation (Group-A, N=39; Group-B, N=29; time interval from collapse to ROSC median 51 min vs 47 min, P=0.47), similar findings in the rate of 30-day survival (58% vs 68%, P=0.53), 30-day favorable neurological finding (33% vs 28%, P=0.61), and complications (36% vs 56%, P=0.11) were observed in Group-A and Group-B.
Conclusions: Cooling duration of more than 36 hours may not provide better neurological outcome, but also increase complications in comatose survivors of out-of-hospital cardiac arrest treated with MTH.