Outcome from severe accidental hypothermia in Southern Finland--a 10-year review

The charts of all adult patients with accidental hypothermia who were admitted to a single academic hospital during a 10 year period were retrospectively retrieved. The aim was to identify factors associated with survival of those with hypothermic cardiac arrest. Of 75 admitted patients, 44 were found to be haemodynamically stable and not to require invasive rewarming measures. Of the remaining 31 patients, 23 were in refractory cardiac arrest due to primary hypothermia and rewarmed using cardiopulmonary bypass (CPB). The aetiology of hypothermia was immersion in cold water in 48%, exposure to cold environment in 39% and submersion in 13% of these patients. Their median age was 50 years, and 83% were males. The patients received a total of 70 min of conventional CPR before institution of CPB. Fourteen of these patients (61%) survived to discharge from hospital. Factors associated with survival were age (P=0.015), arterial pH (P=0.011), PaCO2 (P=0.003), and serum potassium (P=0.007). Logistic regression analysis showed that of the 23 patients, 22 could be correctly classified as survivor or nonsurvivor based on the level of serum potassium and arterial pCO2. It is concluded that patients with cardiac arrest due to primary hypothermia tolerate long periods of conventional CPR before institution of CPB. The possible predictive role of serum potassium and arterial pCO2 needs further evaluation.