Protective Effect of Dexmedetomidine Combined with Butorphanol on Perioperative Pulmonary Function in Patients Undergoing Laparoscopic Colorectal Cancer Resection: A Randomized, Double-Blind, 2 * 2 Factorial-Controlled Trial.

Background: Perioperative lung injury significantly affects the outcome of abdominal surgery. Research has shown that both dexmedetomidine and butorphanol can provide some perioperative lung protection. This study evaluated the protective effects of dexmedetomidine or metoprolol on lung function during laparoscopic resection of colorectal cancer and the potential synergistic effects of their combined use. Methods: A 6-month randomized double-blind placebo-controlled trial with a 2*2 factorial design was conducted at the Affiliated Hospital of Xuzhou Medical University. 176 patients undergoing laparoscopic colorectal cancer resection were randomized into four groups: control (C), dexmedetomidine (D), butorphanol (B), and combination dexmedetomidine + butorphanol (DB). The primary outcome was the arterial-alveolar oxygen partial pressure ratio (a/A ratio) at the end of the administration period (T1). Secondary outcomes included other lung function indices, incidence of postoperative pulmonary complications (PPCs) and other complications, the 15-item Recovery Quality Score (QoR-15) scores, and postoperative inflammatory marker levels. Results: Factorial analysis revealed significant main effects for Group D on the arterial alveolar oxygen partial pressure ratio (a/A ratio) at T1 (F=18.739, P < 0.001, η2=0.098), and Group B (F=19.048, P < 0.001, η2=0.1), with a significant a significant interaction effect between Group D and Group B (F=6.690, P=0.011, η2=0.037). Administration of dexmedetomidine reduced the alveolar-arterial oxygen pressure difference (A-aDO2), intrapulmonary shunt rate (Qs/Qt), and dead space to tidal volume ratio (Vd/Vt) compared to the control. Butorphanol lowered A-aDO2, decreased pulmonary complications on postoperative day 3, reduced postoperative nausea and vomiting, and improved recovery quality. The combination therapy further reduced Vd/Vt, decreased pulmonary complications on postoperative days 1 and 3, and lowered postoperative IL-6 levels. Conclusion: Dexmedetomidine combined with butorphanol enhances lung function in laparoscopic surgery patients by improving gas exchange, boosting ventilation efficiency, reducing inflammation, and decreasing postoperative pulmonary complications.