Introduction

The pathophysiological changes associated with hypothermia make cardiopulmonary resuscitation a unique challenge in patients with severe accidental hypothermia. Hypothermia offers protection from ischemic tissue injury. Therefore, hypothermic patients have survived prolonged periods of untreated cardiac arrest and resuscitation efforts lasting for hours. The arrested hypothermic heart often does not respond to electrical or pharmacological therapy unless rewarmed. Therefore, diagnosis of irreversible cardiorespiratory arrest is difficult during hypothermia and is often defined as “the failure to revive with rewarming”. It is widely accepted that “nobody is dead unless warm and dead.” In addition to basic and advanced cardiac life support adopted to the particular needs of hypothermia, rapid core rewarming is an essential cornerstone of any resuscitation effort. Extracorporeal circulation is considered the method of choice to accomplish core rewarming in arrested hypothermic patients while offering optimal circulatory support.

Pathophysiology of hypothermic cardiac arrest

Hypothermic cardiac arrest may occur in clinically distinct groups of patients. Cardiac arrest may affect otherwise healthy individuals trapped in cold environments, with cardiac arrest being the sole consequence of the deleterious effects of hypothermia on the cardiovascular system. Cardiac arrest may occur in individuals submerged in ice water or snow, who suffer from asphyxia while rapidly cooling. In these patients cardiorespiratory arrest is, at least partly, a consequence of asphyxia, and hypothermia may offer protection from irreversible ischemic injury when substantial hypothermia has developed before cardiac arrest.