Effect of Trendelenburg position on post-induction hypotension in patients undergoing gastrointestinal surgery: A Randomized Clinical Trial

Background Hypotension during general anesthesia induction is common and linked to adverse outcomes. Positioning strategies such as the Trendelenburg position may help improve hemodynamics, but their effectiveness during induction remains unclear. Methods This single-center, prospective, randomized controlled trial was conducted at Zhejiang Cancer Hospital in China from June to August 2024. A total of 70 adult patients (ASA I–III) scheduled for laparoscopic colorectal or gastric cancer surgery were randomly assigned to either the Trendelenburg group (n = 35) or the supine group (n = 35). Immediately after loss of eyelash reflex, patients were positioned in a 10° Trendelenburg or supine position for 15 minutes. Standardized anesthesia, fluid therapy, and vasopressor protocols were applied. The primary outcome was the area under the curve (AUC) for mean arterial pressure (MAP) < 65 mmHg during the first 15 minutes post-induction. Secondary outcomes included AUC for MAP < 60 and < 50 mmHg, duration of hypotension, and drug usage. Statistical analyses involved appropriate non-parametric tests to compare the groups. Results The median AUC for MAP < 65 mmHg was 0 (0–0) mmHg·min in the Trendelenburg group versus 2.03 (0–5.40) mmHg·min in the supine group (P < 0.001). The duration of MAP < 65 mmHg was 0 minutes in the Trendelenburg group compared to 0.92 minutes in the supine group (P < 0.001). Vasopressor use and remifentanil doses were significantly lower in the Trendelenburg group. Conclusions Applying a 10° Trendelenburg position during anesthesia induction significantly reduces the incidence and severity of hypotension in patients undergoing gastrointestinal surgery. Larger multicenter studies are warranted to evaluate the impact on postoperative outcomes and recovery. Trial registration: The trial was registered on June 3, 2024, at http://www.chictr.org.cn/, registration number ChiCTR2400085213.