A double-blind, randomized controlled trial of the use of a 50:50 mixture of nitrous oxide/oxygen in legal abortions

BackgroundThe study was conducted to evaluate the effectiveness of oxygen/nitrous oxide (O2/N2O) in elective abortions by vacuum aspiration with paracervical block and intravenous paracetamol.DesignThis single-center double-blinded randomized study tested O2/N2O (n=36) and placebo (air, n=36) for additional analgesia in elective abortions with paracervical block and intravenous paracetamol. We assessed intra- and postoperative pain according to both a visual analogic scale rated from 0 to 10 and postoperative analgesic requirements.ResultsMean (±SD) intraoperative, immediate postoperative and late postoperative pain did not differ significantly for patients with O2/N2O and with air [3.4±2.6 vs. 3.7±3.05 (p=.75), 1.89±2.4 vs. 1.56±2.03 (p=.78), 0.5±0.8 vs. 0.75±1.2 (p=.45)]. The number of patients with scores for low (0–4), moderate (4–7) and severe (7-10) intraoperative, immediate postoperative and late postoperative pain did not differ significantly between the groups. Total adverse effects were significantly higher in the O2/N2O group [35/180 (19.4%) vs. 18/180 (10%), p=.01].ConclusionO2/N2O did not reduce intraoperative or postoperative pain in elective abortions by vacuum aspiration with paracervical analgesia and intravenous paracetamol, and its adverse effect rate was substantial.