Butorphanol premedication improves postoperative lung function and analgesic outcomes in laparoscopic surgery: a randomized dose-response study

In laparoscopic surgery, balancing effective analgesia with preservation of pulmonary function remains a clinical challenge. Butorphanol, a κ-opioid receptor agonist and partial µ-opioid receptor agonist, may offer advantages in respiratory protection and anti-inflammatory effects.

This prospective, randomized, double-blind, three-arm, single-center clinical trial was conducted at the Affiliated Hospital of Zunyi Medical University. Between June 2021 and December 2023, a total of 81 patients undergoing elective laparoscopic surgery were enrolled, including 28 in the control group, 27 in the low-dose butorphanol group (1 mg), and 26 in the high-dose butorphanol group (2 mg). All patients received an intramuscular injection of the assigned study drug 30 min before anesthesia induction. The primary outcome was intraoperative pulmonary gas exchange, including arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂₂), and end-tidal carbon dioxide (ETCO₂). Secondary outcomes included intraoperative ventilatory mechanics, perioperative pulmonary function, inflammatory markers, postoperative analgesia, anesthetic drug consumption, and follow-up outcomes up to 9 months after surgery.

Compared with the control group, butorphanol-particularly at 2 mg-significantly improved intraoperative pulmonary gas exchange. The high-dose group showed greater benefits in reducing airway pressures and anesthetic requirements, improving postoperative pulmonary function, suppressing inflammatory responses, and enhancing analgesic effects. During the 9-month follow-up, 70 patients completed all assessments, and the high-dose group consistently demonstrated superior recovery of pulmonary function, better quality of life, and lower levels of chronic pain.

Pre-induction butorphanol enhances intraoperative pulmonary gas exchange and improves secondary outcomes, with 2 mg showing the most consistent benefits for ERAS protocols.

The study has been registered with the Chinese Clinical Trial Registry, registration number: ChiCTR2100047900. Registration date: June 27, 2021. Not retrospectively registered.