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.