Effect of targeted temperature management on systemic inflammatory responses after out-of-hospital cardiac arrest: A prospective cohort study

Background: Interleukin (IL)-6 is a major inflammatory cytokine that predicts mortality after out-of-hospital cardiac arrest (OHCA). Targeted temperature management (TTM) is associated with improved all-cause mortality in patients with OHCA. However, the effect of TTM on IL-6 production remains unclear. This study investigated whether TTM has additional anti-inflammatory effects after OHCA. Methods: This prospective cohort study included a total of 141 hospitalized patients with OHCA who were treated between January 2015 and June 2023. The study was conducted in the intensive care unit of China Medical University Hospital, Taichung. Postcardiac arrest care included TTM or the control approach (no TTM). The primary outcomes included the 90-day mortality rate and neurologic outcomes after OHCA. Differences between the TTM and control groups were examined using Student t test, chi-square test, and Kaplan-Meier survival curve analysis. Multivariate analysis of variance model was used to examine interaction effects. Results: Plasma IL-6 and IL-6/soluble IL-6 receptor complex levels were measured at 6 and 24 hours after resuscitation. IL-6 and IL-6/soluble IL-6 receptor complex production was lower in the TTM group than in the control group (-50.0% vs +136.7%, P < .001; +26.3% vs +102.40%, P < .001, respectively). In addition, the 90-day mortality rate and poor neurologic outcomes were lower in the TTM group than in the control group (36.8% vs 63.0%, relative risk 0.39, 95% confidence interval 0.24-0.64, P < .001; 65.5% vs 81.5%, relative risk 0.80, 95% confidence interval 0.66-0.98, P = .04). Conclusion: TTM improves both the mortality rate and neurologic outcomes in patients resuscitated from OHCA, possibly by reducing IL-6-induced proinflammatory responses.