Prognosis

Generally, patients with mild hypothermia will recover without any residual effects.[19]​ Resuscitation and recovery of patients with moderate and severe hypothermia depends on several factors such as cold exposure duration, associated injuries, comorbidities, and the degree of hypothermia. The triad of coagulopathy, acidosis, and hypothermia is associated with increased mortality, particularly among patients with severe injuries.[2][3]

The lowest ever recorded temperature in a patient successfully resuscitated from accidental hypothermia with circulatory arrest is 56.7°F (13.7°C).[62]​ Good physical and mental recovery was also reported in this case. Numerous case reports in the literature have also demonstrated the potential of successful resuscitation with good neurologic recovery even in cases of prolonged cardiac arrest.[63][64]​​​​​ Patients should not be declared dead prior to full resuscitative measures and aggressive rewarming, unless in the case of nonsurvivable traumatic injury or rigor mortis.[45]​​

Evidence suggests that extracorporeal life support (ECLS) offers a better survival outcome than other treatment modalities in patients with hemodynamic instability and cardiac arrest.[19][57][58][65][66]​​​​​​​​ One systematic review found that ECLS rewarming was associated with an 80% survival probability at 5 months follow-up; only 19.4% of survivors reported any long-term cognitive impairments.[57]​ Survival was associated with serum potassium, initial body temperature, and ECLS rewarming rate, although patient age was not found to be significantly associated.[57]​ Slower rewarming rates of ≤41°F (≤5.0°C) per hour are associated with improved survival with good neurologic outcomes.[66]

One retrospective cohort study among patients with moderate and severe hypothermia from the International Hypothermia Registry found a 95% survival rate for patients with preserved circulation, and a 36% survival rate for patients with hypothermic cardiac arrest.[17]​ The majority of cases were secondary to mountaineering accidents in young, healthy men. The study found that predictors of survival included witnessed cardiac arrest, restoration of spontaneous circulation, low potassium and lactate, and the absence of asphyxia.[17]

Serum potassium is part of the HOPE (Hypothermia Outcome Prediction after ECLS rewarming for hypothermic arrested patients) score for prognostication of successful rewarming.[20][48] [ Hypothermia outcome prediction after ECLS (HOPE) score Opens in new window ]

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