Effects of Different Fresh Gas Flow Rates on Body Temperature and Postoperative Nausea and Vomiting in Morbidly Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy

Introduction: Inadvertent perioperative hypothermia and postoperative nausea and vomiting (PONV) remain common after metabolic and bariatric surgery (MBS). Fresh gas flow (FGF) may influence heat and humidity conservation within the breathing circuit and thereby affect perioperative temperature and PONV. Methods: In this single-center, randomized, prospective trial, 161 adults with obesity class III (BMI > 40 kg/m²) scheduled for laparoscopic sleeve gastrectomy were allocated to normal-flow (2.0 L/min; n=53), low-flow (1.0 L/min; n=55), or minimal-flow anesthesia (0.5 L/min; n=53). Esophageal and tympanic temperatures and hemodynamic variables were recorded every 10 minutes intraoperatively. PONV was assessed in the post-anesthesia care unit (PACU) and at 6, 12, and 24 hours postoperatively. Results: Baseline characteristics were comparable among groups. From the 20th minute onward, esophageal and tympanic temperatures differed between groups (p<0.001), with higher temperatures in the minimal-flow group. The proportion of patients without PONV in the PACU and at 6, 12, and 24 hours was highest with minimal-flow anesthesia and lowest with normal-flow anesthesia (p<0.05). Perioperative SpO₂, heart rate, and mean arterial pressure were similar across groups (p>0.05). Conclusion: Minimal-flow anesthesia (0.5 L/min) better preserved perioperative temperature and was associated with lower PONV after laparoscopic sleeve gastrectomy, without compromising hemodynamic stability.