Inhaled nitrous oxide provides efficacious analgesia for outpatient hysteroscopic procedures

The use of inhaled nitrous oxide during outpatient operative hysteroscopy helps reduce intraprocedural pain and promote successful completion of procedures, resulting in increased patient satisfaction, according to a study.

The study was conducted at a single university-affiliated tertiary care hospital and included 214 women undergoing office-based operative hysteroscopy. These participants were randomly assigned to receive either inhaled nitrous oxide (n=110; mean age 35 years, mean BMI 25.3 kg/m², 17.3 percent premenopausal) or ambient air (n=104; mean age 33.5 years, mean BMI 24.2 kg/m², 17.3 percent premenopausal) through a self-administered face mask.

The primary outcome of pain was assessed during the procedural stages using the visual analogue scale (VAS). Secondary outcomes included the incidence of adverse effects, procedure completion rate, and patient satisfaction.

Compared with ambient air, nitrous oxide was associated with significantly reduced intraprocedural pain (mean VAS score, 2.23 vs 3.96; p<0.001). The analgesic effect of nitrous oxide vs ambient air was notably stronger for postmenopausal women, with significantly lower pain both at uterine entry (mean VAS score, 5.47 vs 8; p=0.013) and during the procedure (mean VAS score, 2.42 vs 6.56; p=0.002).

Procedure completion rates were higher in the nitrous oxide group than the ambient air group, at 93.6 percent vs 83.7 percent (p=0.021). Significantly more participants in the nitrous oxide group expressed willingness to repeat the procedure with the same inhaled agent (80.9 percent vs 47.1 percent; p<0.001).