Partial cardiopulmonary bypass for core rewarming in profound accidental hypothermia

Six cases of treatment of severe accidental hypothermia using cardiopulmonary bypass for core rewarming are reported and eleven cases from the literature are analyzed. Thirteen patients survived. Overall survival was more likely in patients who had vital signs initially. Initial mean core temperatures in the new cases was 22.8 C. Surface and conventional core rewarming methods resulted in an average temperature increase of 2.4 C per hr. Electrical defibrillation was generally without success until the core temperature had been raised to above 30 C. Between one and six hours after admission, partial femoral-femoral cardiopulmonary bypass (CPB) for core rewarming was started, causing a mean temperature increase of 9.5 C per hr. Four patients required a thoracotomy. Two patients had a massively dilated heart with contusions, and could not be weaned off bypass. None of the four long-term survivors had a demonstrable central nervous system (CNS) deficit. All patients developed temporary pulmonary problems; two developed wound infections. The average hospital stay was 21 days. CPB for core rewarming allows circulatory support while avoiding myocardial damage from prolonged external cardiac massage; rapidly increases the myocardial temperature and counteracts myocardial temperature gradients so that DC electroversion is successful; avoids "rewarming shock"; and improves microcirculatory flow. A prospective randomized trial to compare rapid surface rewarming and CPB rewarming is suggested. Immediate CPB for rewarming is recommended for patients in ventricular fibrillation with core temperatures below 30 C. Prolonged external cardiac massage (ECM) should not be used. The value of surface rewarming and non-CPB core rewarming methods remains undefined.