Thermoregulation in post-cardiac arrest patients treated with targeted temperature management

Objective: Evaluate the relationship between heat generation during rewarming in post-cardiac arrest patients receiving targeted temperature management (TTM) as a surrogate of thermoregulatory ability and clinical outcomes.

Methods: This is a prospective observational single-centre study conducted at an urban tertiary-care hospital. We included post-cardiac arrest adults who received TTM via surface cooling device between April 2018 and June 2019.

Results: Patient heat generation was calculated by multiplying the inverse of the average machine water temperature with time to rewarm to 37 °C and standardized in two ways to account for target temperature variation: (1) divided by number of degrees between target temperature and 37 °C, and (2) limited to when patient was rewarmed from 36 °C to 37 °C. The primary outcome was poor neurologic status, defined as Cerebral Performance Category (CPC) score 3-5, and the secondary outcome was 30-day survival. Sixty-six patients were included: 45 (68%) had a CPC-score of 3-5 and 23 (35%) were alive at 30 days. Besides initial rhythm and arrest downtime, baseline characteristics were similar between outcomes. Heat generation was not associated with poor neurological outcome (CPC 3-5: 6.6 [IQR: 6.1, 7.4] versus CPC 1-2: 6.6 [IQR: 5.7, 7.6], p = 0.89) or survival at 30 days (non-survivors: 6.6 [IQR: 6.6, 7.4] vs. survivors: 6.6 [IQR: 5.7, 8.0, p = 0.78]).

Conclusion: Heat generation during rewarming was not associated with neurologic outcomes. However, there was a relationship between poor neurological outcome and higher median water temperatures. Time to rewarm was prolonged in patients with poor neurological outcome.