Nitrous Oxide Inhalation and Chronic Postsurgical Pain in Thoracoscopic Lobectomy Patients: A Prospective Cohort Study

Abstract

Background: Chronic postsurgical pain is a significant detriment to postsurgical recovery. Previous studies have shown that nitrous oxide may produce long-term analgesia and may benefit the prevention of chronic postsurgical pain in Asian patients. We tested the hypothesis that nitrous oxide is a protective factor against chronic pain after thoracoscopic lobectomy. Methods: Two groups of patients with and without nitrous oxide inhalation during video-assisted thoracic surgery in Peking Union Medical College Hospital were recruited. Perioperative information was documented, and postsurgical pain was followed up by telephone. The primary outcome was the presence of chronic postsurgical pain at 6 months postoperatively. Odds ratios and their 95% confidence intervals were estimated using a multivariate logistic regression model adjusted for relevant confounding factors. Results: A total of 833 patients were eligible, among whom 33.6% were male and 66.4% were female, with an average age of 56.3 ±11.1 years. A total of 387 (46.5%) patients reported incision-related pain at 6 months after surgery, and 160 (40.0%) out of 400 patients with nitrous oxide inhalation during surgery and 227 (52.4%) out of 433 patients without nitrous oxide inhalation during surgery developed chronic postsurgical pain. After adjusting for confounding factors, nitrous oxide inhalation during surgery was associated with lower odds of chronic postsurgical pain (OR=0.654; 95% CI, 0.480–0.890, P=0.007). Conclusions: Nitrous oxide inhalation during surgery was associated with lower odds of CPSP in VATS patients, and nitrous oxide may benefit the management of chronic pain related to thoracoscopic surgery. Trial registration: This study was registered in ClinicalTrials.gov on January 1, 2018, with registration number of NCT03363672.