Nitrous Oxide for Pain Management During In-Office Hysteroscopic Sterilization

Abstract

INTRODUCTION: To evaluate whether inhaled nitrous oxide with oxygen (N2O/O2) is superior to oral sedation for pain management during in-office hysteroscopic sterilization. METHODS: This double blinded randomized controlled trial enrolled women undergoing in-office hysteroscopic sterilization. The intervention group received N2O/O2 titrated to a maximum 70%:30% mixture and placebo pills pre procedure. The control group received inhaled O2 during the procedure and 5/325 mg hydrocodone/acetaminophen and 1 mg lorazepam pre procedure. The primary outcome was maximum procedural pain on a 100 mm Visual Analogue Scale (VAS) assessed 3–5 minutes post procedure. A sample size of 30 women per treatment arm was required to detect a clinically significant pain difference of 20 mm on the VAS. RESULTS: 72 women, 36 per study arm, were randomized to account for unsuccessful bilateral coil placement and drop out after randomization. Two women in the study group and 6 in the control group were excluded due to unsuccessful bilateral coil placement. Mean age of participants was 34.1±5.7 years and mean BMI was 30.1±6.6 kg/m2. Mean maximum procedural pain scores were 22.8±27.6 mm and 54.5±32.7 mm for study and control groups, respectively (P<.001). Most study participants (97%) stated NOS should be offered for gynecologic office procedures and 86% would pay for NOS if it were not a covered benefit. CONCLUSION: NOS decreased pain with in-office hysteroscopic sterilization compared to oral sedation. Given its safety and favorable side effect profile, NOS should be considered for routine availability for in-office hysteroscopic sterilization.