Accidental hypothermia (AH) can be caused by exposure to cold weather conditions, immersion in water, avalanche burial in snow, or indoors, mostly affecting elderly patients with multiple comorbidities.^1,2 There are three stages of AH.³ In mild AH core temperatures are 35°C–32°C (95°F–89.6°F) and mental status is normal or mildly impaired. In moderate AH with core temperatures between 32°C–28°C (89.6°F–82.4°F), patients may be unconscious or conscious with altered mental status. In severe AH with core temperatures <28°C (82.4°F), patients are unconscious. Pathophysiologic changes caused by hypothermia affect the cardiovascular system, leading to dysrhythmias, impaired cardiac output, and cardiac arrest (CA).^4–7 There may be significant morbidity and mortality but there may also be favorable outcomes.^8–11 Patients with core temperatures <28°C (82.4°F) without CA can be rewarmed by conventional rewarming methods. In unstable patients, extracorporeal life support (ECLS)—extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass—is more effective than conventional means because it provides cardiorespiratory support in addition to rewarming.^3,8,12–17 Extracorporeal membrane oxygenation can also be used to provide post-rewarming cardiorespiratory support if necessary.

Patient selection, outcome prediction, and treatment depend on logistics and planning, including planning for the implementation of ECLS.^18,19 The risk of CA is high in young, healthy patients with core temperatures <28°C (82.4°C), and in elderly patients or patients of any age with comorbidities and core temperatures <30°C (86°F). These patients should be transferred to centers capable of providing ECLS.²⁰ The ICE-CRASH study showed that treatment with ECMO was significantly associated with improved 28 day survival and favorable neurological outcomes at hospital discharge in patients with CA compared with those who did not receive ECMO (odds ratio [OR]: 0.17, 95% confidence interval [CI]: 0.05–0.58, and OR: 0.22, 95% CI: 0.06–0.81).²¹ Indications for ECLS rewarming in severely hypothermic patients with preserved circulation have not been precisely established, and the data on outcomes are conflicting. In one study, ECMO did not improve survival or neurological outcomes and increased treatment duration and frequency of bleeding complications.²¹ Two other studies found that patients with severe hypothermia and cardiovascular instability might benefit from extracorporeal rewarming without an increased risk of complications. The survival rate was higher in patients rewarmed with ECLS. The relative risk of death was twice as high in patients rewarmed by less invasive means.²² Eligibility for ECLS should not be based on core temperature alone or on the stage of hypothermia but also on the condition of the patient.

This expert consensus Extracorporeal Life Support Organization (ELSO) guideline gives recommendations for the use of ECLS for cardiorespiratory support and for rewarming in severe AH.