The administration of an equimolar mixture of nitrous oxide-oxygen (N₂O) is recommended during painful procedures. However, the evaluation of its use during physiotherapy after surgery has not been reported, although pain may hamper physiotherapy efficiency. This study investigated whether the use of N₂O improves the efficacy of post-operative physiotherapy after multilevel surgery in patients with cerebral palsy.

It was a randomised 1:1, double-blind, placebo-controlled study. Sixty-four patients were enrolled. All patients had post-operative physiotherapy starting the day after surgery. Patients received either N₂O or placebo gas during the rehabilitation sessions. All patients had post-operative pain management protocol, including pain medication as needed for acute pain. The primary objective was to reach angles of knee flexion of 110° combined with hip extension of 10°, with the patient lying prone, within 6 or less physiotherapy sessions. Secondary evaluation criteria were the number of sessions required to reach the targeted angles, the session-related pain intensity, and the analgesics consumption for managing post-operative pain.

Targeted angles were achieved more often in the N₂O group (23/32, 72%, vs. Placebo: 13/32, 41%; P=0.01).

Patients treated with N₂O tended to require less often level III analgesic agents for managing post-operative pain, compared to those receiving placebo: 18/32 (58%) vs. 24/32 (75%).

The administration of N₂O during post-operative physiotherapy can help to achieve more quickly an improved range of motion, and, although not significant in our study, to alleviate the need for pain medication. Further studies evaluating the administration of N₂O in various settings are warranted.