Cardiac arrest secondary to environmental hypothermia: Incidence and outcomes in an urban emergency department in the Upper Midwestern United States.

OBJECTIVES

Data describing hypothermic cardiac arrest (HCA) outcomes predominantly originate from patients involved in wilderness accidents. We describe the incidence and outcomes of HCA in an urban environment, with a subgroup analysis of patients with witnessed HCA in the prehospital or emergency department (ED) setting.

METHODS

We completed a retrospective, single center cohort analysis of consecutive adult patients with environmental exposure and core body temperature ≤ 32 °C. We describe characteristics of this cohort and evaluate the relationship between initial core temperature and occurrence of HCA.

RESULTS

171 patients met eligibility criteria from January 2007 to September 2023. 43 (25 %) sustained HCA, including 6/98 (6 %) of those with moderate hypothermia (28.01-32 °C), 21/55 (38 %) with severe hypothermia (24-28 °C) and 16/18 (89 %) with profound hypothermia (<24 °C). Risk of HCA increases 2.06 times (95 % CI 1.66 to 2.69) for each 1 °C decrease in initial core temperature below 32 °C. Among HCA patients, 18/43 (42 %) had a witnessed HCA during prehospital (n = 8) or ED (n = 10) care. The overall survival rate of HCA was 53 % but was higher in patients with initial core temperature < 28 °C versus those >28C (62 % vs 0 %). Survival of hypothermic patients who experienced their first HCA after arrival in the ED approached that of hypothermic patients without HCA (90 % vs 94 %).

CONCLUSION

Patients with severe hypothermia secondary to environmental exposure in an urban environment are at high-risk of HCA. Witnessed HCA accounts for a significant portion of HCA patients, and patients with witnessed HCA in an ED setting can achieve excellent outcomes.