Relationship between cooling time and neurological outcomes in targeted temperature management

Objectives: The relationship between cooling time (CT) variables and neurological outcomes is controversial. We evaluated the relationship between CT and neurological outcomes in out-of-hospital cardiac arrest (OHCA) patients treated with targeted temperature management (TTM). Methods: We conducted a multicenter, prospective, and registry-based study of OHCA survivors treated with TTM. CT was defined as the time from restoration of spontaneous circulation to achievement of the target temperature. The primary outcome was a favorable neurological outcome at 6 months. Multilevel logistic regression analysis was performed to test the relationship between CT and the primary outcome. Results: Overall, the favorable neurological outcome rates at 6 months were 29.8% in 937 patients. When CT was stratified into categories of 0–3, 3.1–6, 6.1–9, 9.1–12, and >12 h, according to 3-h intervals, the primary outcome rates were 8.2%, 22.7%, 35.5%, 44.7%, and 44.5%, respectively (p < 0.001). Significant differences were not found in multilevel logistic regression analysis; the adjusted odds ratios (95% confidence interval) of each category for the primary outcome compared to the 0–3-h group were 0.81 (0.32 to 2.04), 0.77 (0.30 to 2.01), 1.26 (0.43 to 3.68), and 1.06 (0.37 to 3.06). Conclusions: We did not find a relationship between CT and neurological outcomes at 6 months.