Abstract 7: Mild Therapeutic Hypothermia Using Extracorporeal Cooling Method In Comatose Survivors After Out-Of-Hospital Cardiac Arrest
BACKGROUND Although therapeutic hypothermia using external cooling methods can improve the chance of neurological recovery, the neurological benefit is limited to about a half of unconscious adult patients with return of spontaneous circulation (ROSC) after out-of-hospital ventricular fibrillation (VF). We conducted a prospective preliminary study of therapeutic mild hypothermia using extracorporeal cooling methods, and compared the outcome of this study with that of patients treated with normothermia from the SOS-KANTO study.
METHODS The criteria for entry these studies was the same as the European hypothermia study ( N. Engl. J. Med 2002; 346: 549–56), except initial cardiac rhythm. The protocol of the hypothermia was as follows: Core temperature was monitored by the bladder temperature until a pulmonary-artery catheter was placed. Intravenous infusion of 1,500~2,000ml of extracellular fluid at 4 degrees centigrade over 30 minutes was immediately initiated after emergency room arrival.Subsequently, patients were cooled to a target temperature of 34 degrees centigrade with the use of an extracorporeal cooling device (KTEK-3, Kawasumi-Co, JAPAN) within 2 hours after the ROSC, and this temperature was maintained precisely for 24 hours when collapse-to-ROSC interval was within 20 minutes, 48 hours when that interval was 20 to 30 minutes, and 72 hours when that interval was more than 30 minutes. The primary endpoint was a favorable neurological outcome at the time of hospital discharge.
RESULTS A total of 566 patients were enrolled; 30 were treated with the hypothermia and 539 were treated with the normothermia. Among patients with VF/VT as an initial cardiac rhythm, 17 of the 22 (77.3%) patients in the hypothermia group had a favorable neurological outcome, as compared with 80 of 207 (38.6%) patients in the normothermia group (p<0.001). In addition among patients with PEA or asystole, the hypothermia group was associated with an improvement of a favorable neurological outcome compared with the normothermia group (25% vs 7%, p=0.05).
CONCLUSIONS Extracorporeal cooling method may be a preferable approach to mild therapeutic hypothermia in comatose survivors after out-of-hospital cardiac arrest with either VF/VT or PEA/asystole.