The Protective Effects of Butorphanol on Pulmonary Function of Patients with Obesity Undergoing Laparoscopic...

Obesity is a risk factor for postoperative pulmonary complications (PPCs). Recent studies have reported the pulmonary protective role of the kappa opioid receptor (KOR). Butorphanol is a narcotic with strong KOR agonist action, and the role in pulmonary protection is uncertain. Here, we hypothesized that butorphanol exerts protective effects on pulmonary function in patients with obesity undergoing laparoscopic bariatric surgery.

Patients with a body mass index ≥ 30 kg/m² scheduled for laparoscopic bariatric surgery were randomized to receive butorphanol or normal saline. Butorphanol was administered as an initial loading dose of 10 μg/kg at 5 min before induction followed by 5 μg/(kg h) during surgery. The primary outcome was arterial-alveolar oxygen tension ratio (a/A ratio). Secondary outcomes included other pulmonary variables, biomarkers reflecting pulmonary injury, and incidence of PPCs within 7 days after surgery.

Patients in the butorphanol group had a significantly higher a/A ratio at 1 h after the operation began (68 ± 7 vs. 55 ± 8, P < 0.001), end of the operation (73 ± 8 vs. 59 ± 7, P < 0.001), and 1 h after extubation (83 ± 9 vs. 70 ± 5, P < 0.001) compared with those in the control group. In addition, in the butorphanol group, dead space to tidal volume ratios were significantly lower than those in the control group at the same time points (all P < 0.001). In the control group, the levels of biomarkers reflecting pulmonary injury were significantly higher than those in the butorphanol group at 3 h, 6 h, 12 h, and 24 h postoperatively (P < 0.001). The incidence of PPCs was similar in both groups.

Butorphanol administration protected pulmonary function by improving oxygenation and reducing dead space ventilation in patients with obesity undergoing laparoscopic bariatric surgery. Butorphanol may therefore provide clinical benefits in patients with obesity.