Effectiveness of 33 °C targeted temperature management in patients with out-of-hospital cardiac arrest after resuscitation: a retrospective study

BACKGROUND: Controversy exists regarding the selection of the target temperature for patients with out-of-hospital cardiac arrest (OHCA). This study aims to identify the subgroups of patients who can benefit from targeted temperature management (TTM) at 33 °C. METHODS: We retrospectively analyzed 282 OHCA patients, who were categorized based on the administration of 33 °C TTM and early mortality within 24 h of ICU admission. The median value was used to determine the cutoff for continuous variables, and patients were further divided into subgroups according to different variables; the outcomes were survival status and neurological function at discharge. Difference analysis, multivariate logistic regression (MLR), and propensity score matching (PSM) were applied to analyze the efficacy of different TTM regimens in each subgroup. RESULTS: Subgroup analysis showed that 33 °C TTM was associated with better survival only in patients without bystander CPR (OR [95%CI]: 3.41 [1.13, 10.31], P = 0.029), whereas this association disappeared after MLR and PSM adjustment. Among patients with an APACHE II score < 30, the Non-33 °C TTM group presented a more favorable neurological prognosis (χ²: OR [95%CI]: 0.34 [0.17, 0.70], P = 0.003; MLR: 0.29 [0.08, 0.96], P = 0.046). 33 °C TTM stable group was related to superior survival only in the APACHE II > 30 subgroup in MLR analysis (OR [95%CI]: 3.47 [1.09, 12.32], P = 0.042). After MLR and PSM adjustment, favorable neurological outcomes remained significantly higher in the Non-33 °C TTM stable group among patients with cardiac etiology (MLR: OR [95%CI]: 0.25 [0.06, 0.94], P = 0.046; PSM: 0.08 [0.01, 0.51], P = 0.017) and those with APACHE II < 30 (MLR: OR [95%CI]: 0.27 [0.07, 0.88], P = 0.034; PSM: 0.19 [0.04, 0.80], P = 0.029). CONCLUSIONS: 33 °C and Non-33 °C TTM strategies were associated with clinical outcomes in specific subgroups of OHCA patients, and further studies are warranted to clarify this association.