Effects of different warming strategies on intraoperative hypothermia: a systematic review and network meta-analysis of randomized controlled trials

BACKGROUND: The purpose of this network meta-analysis was to assess the effect of different active warming strategies on intraoperative hypothermia (IH). METHODS: Databases of PubMed, Web of Science, Embase, and Cochrane Library were searched for randomized controlled trials that were published from 1 January 2015 to 20 September 2025. The incidence of IH was the primary outcome. RESULTS: A total of 45 studies comprising 5317 patients were included in this study. Among the single warming strategies, both thermal suit [RR = 0.45, 95% CI (0.16, 1.27)] and irrigation fluid warming [RR = 0.95, 95% CI (0.27, 3.30)] demonstrated a numerically lower incidence of IH compared with forced-air warming (FAW). For FAW blanket type, the incidence of IH in FAW-Lower-body [RR = 1.54, 95% CI (1.17, 2.04)] and FAW-Surgical-access blanket [RR = 1.44, 95% CI (1.01, 2.06)] was significantly higher than that in FAW-Underbody. Compared with FAW alone, multiple combined warming strategies without prewarming exhibited numerically reduced IH incidence, such as irrigation fluid warming + intravenous fluid warming + FAW [RR = 0.44, 95% CI (0.04, 4.40)]. Compared with FAW alone, prewarming + FAW showed significantly lower IH incidence [RR = 0.66, 95% CI (0.45, 0.96)]. CONCLUSION: FAW remains the pragmatic standard for preventing IH, with the underbody type preferred whenever clinically feasible. We conditionally recommend combining FAW with prewarming and fluid warming in high-risk contexts (particularly for older patients and prolonged surgery), although wide prediction intervals suggest these added benefits should be interpreted cautiously. TRIAL REGISTRATION: PROSPERO Registration Number: CRD420251148645.