Pain
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Randomized Controlled Trial Multicenter Study
Chronic postsurgical pain after nitrous oxide anesthesia.
Nitrous oxide is an antagonist at the N-methyl-D-aspartate receptor and may prevent the development of chronic postsurgical pain. We conducted a follow-up study in the Evaluation of Nitrous Oxide in the Gas Mixture for Anaesthesia (ENIGMA) trial patients to evaluate the preventive analgesic efficacy of nitrous oxide after major surgery. The ENIGMA trial was a randomized controlled trial of nitrous oxide-based or nitrous oxide-free general anesthesia in patients presenting for noncardiac surgery lasting more than 2 hours. ⋯ In addition, severe pain in the first postoperative week, wound complication, and abdominal incision increased the risk of chronic pain. In conclusion, chronic postsurgical pain was common after major surgery in the ENIGMA trial. Intraoperative nitrous oxide administration was associated with a reduced risk of chronic postsurgical pain.