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.