Hospital resuscitation in patients with primary hypothermic cardiac arrest.

Hypothermia is recognised as a reversible cause of cardiac arrest along with hypoxia, hypovolaemia and hypo or hyperkalaemia. However, hypothermia is the rarer one of these 'four Hs'. Because cardiac arrest caused primarily by hypothermia is a rare occurrence, resuscitation teams may lack real-world experience of it. This article sets out essential information for emergency department staff to understand this presentation and its management. It provides background information on hypothermia, describes the usual pattern of deterioration leading to cardiac arrest, and explains the key interventions required to give patients the best chance of survival, whether or not extracorporeal life support is accessible. It details the guideline recommendations that differ from standard advanced life support procedures and are specific to the management of hypothermic patients in cardiac arrest.