A model for the treatment of accidental severe hypothermia

Central to the controversy that surrounds the treatment of accidental severe hypothermia is the question of how the method of rewarming affects myocardial performance, and therefore survival. We induced severe hypothermia and cardiac arrest in 15 mongrel dogs. Each dog was rewarmed by one of three methods: partial cardiac bypass (Group I); peritoneal dialysis (Group II); or external rewarming with a fluid-circulated blanket (Group III). The cardiac arrest state was supported by partial cardiac bypass in Group I and by standard mechanical cardiopulmonary resuscitation (CPR) in Groups II and III. In all dogs, the hypothermically depressed myocardial performance returned to normal upon rewarming. Groups I and II had similar rewarming times and required similar volumes of crystalloid and bicarbonate solutions to maintain adequate cardiac filling pressures and arterial pH. However, Group III had a significantly slower rewarming time and required significantly greater volumes of crystalloid and bicarbonate solutions. The sole procedural death occurred in Group III. Our results show that partial cardiac bypass, peritoneal dialysis, and the fluid-circulated blanket are equally effective in rewarming severely hypothemic dogs with cardiac arrest, provided that the cardiac arrest is relieved by partial cardiac bypass or standard mechanical CPR and that physiologic levels of intravascular volume, oxygenation, and pH are maintained.