Relationship between time to target temperature and outcome in patients treated with therapeutic hypothermia after cardiac arrest

Introduction: Our purpose was to study whether the time to target temperature correlates with neurologic outcome in patients after cardiac arrest with restoration of spontaneous circulation treated with therapeutic mild hypothermia in an academic emergency department. Methods: Temperature data between April 1995 and June 2008 were collected from 588 patients and analyzed in a retrospective cohort study by observers blinded to outcome. The time needed to achieve an esophageal temperature of less than 34 degrees C was recorded. Survival and neurological outcomes were determined within six months after cardiac arrest. Results: The median time from restoration of spontaneous circulation to reaching a temperature of less than 34 degrees C was 209 minutes (interquartile range [IQR]: 130-302) in patients with favorable neurological outcomes compared to 158 min (IQR: 101-230) (P < 0.01) in patients with unfavorable neurological outcomes. The adjusted odds ratio for a favorable neurological outcome with a longer time to target temperature was 1.86 (95% CI 1.03 to 3.38, P = 0.04). Conclusions: In comatose cardiac arrest patients treated with therapeutic hypothermia after return of spontaneous circulation, a faster decline in body temperature to the 34 degrees C target appears to predict an unfavorable neurologic outcome.