Effect of Intraoperative Active Warming Initiated at Anesthesia Induction on Core Temperature, Postoperative Pain and...

Background and Objectives: Inadvertent perioperative hypothermia is a common and clinically significant complication during laparoscopic surgery, leading to pain, agitation, shivering, and delayed recovery. This randomized controlled trial evaluated the effect of peri-induction active warming with an electric resistive blanket on postoperative pain and agitation-the primary outcomes-compared with passive insulation. Materials and Methods: This study was registered at ClinicalTrials.gov (Identifier: NCT06022926; date of registration: 15 August 2023) prior to the enrollment of the first patient. One hundred and thirty-two American Society of Anesthesiologists I-II adults undergoing laparoscopic cholecystectomy were randomly allocated (1:1) to two groups: one received active warming with a resistive carbon fiber underbody blanket (Group 1), and the other received passive insulation (Group 2). The tympanic core temperature was measured at four perioperative time points (TT1-TT4). Postoperative agitation (Riker Sedation-Agitation Scale, RSAS) and pain (Numerical Rating Scale, NRS) were assessed 20 min after extubation in the post-anesthesia care unit (PACU). Secondary outcomes included intraoperative and postoperative temperature, postoperative shivering, adverse events (bradycardia, tachycardia, hypotension, hypertension, postoperative nausea and vomiting, and respiratory depression), and the PACU length of stay. Results: Baseline core temperatures (TT1) were similar between the groups (36.5 ± 0.55 °C vs. 36.6 ± 0.54 °C; p = 1.00). However, mean core temperatures at TT2, TT3, and TT4 were significantly higher in the active warming group compared with the control group (TT2: 36.7 ± 0.53 °C vs. 36.5 ± 0.54 °C; TT3: 36.6 ± 0.49 °C vs. 36.4 ± 0.54 °C; TT4: 36.6 ± 0.51 °C vs. 36.2 ± 0.52 °C; all p < 0.001). Active warming markedly reduced postoperative agitation (RSAS ≥ 5: 3.1% vs. 19.4%, p = 0.004) and pain (NRS ≥ 4: 15.4% vs. 49.3%, p < 0.001). The incidence of shivering was lower (20.0% vs. 46.3%, p = 0.006), and the PACU stay was shorter (24 [23-28] min vs. 35 [30-40] min, p < 0.001) with active warming. No significant differences in adverse events were observed between groups. Logistic regression identified the intraoperative fentanyl dose as a predictor of agitation and identified shivering and the PACU duration as predictors of pain. Conclusions: Peri-induction active warming effectively maintained normothermia and improved recovery quality by reducing postoperative agitation, pain, shivering, and PACU stays without increasing adverse events. It should be considered a standard component of thermal management in short- and medium-duration laparoscopic surgeries.