Nitrous Oxide Compared With Intravenous Sedation for Second-Trimester Abortion: A Randomized Controlled Trial

Area of Science:

• Obstetrics and Gynecology
• Pain Management
• Anesthesiology

Background:

• Surgical abortion in the second trimester (12-16 weeks gestation) requires effective pain management.
• Both inhaled nitrous oxide and intravenous (IV) sedation are options for pain control during outpatient procedures.

Purpose of the Study:

• To compare the efficacy of inhaled nitrous oxide versus IV sedation for pain control during second-trimester surgical abortions.
• To determine if inhaled nitrous oxide is noninferior to IV sedation for pain management in this patient population.

Main Methods:

• A multisite, double-blind, randomized clinical trial was conducted.
• Participants received either 70% nitrous oxide/30% oxygen or IV fentanyl and midazolam, with paracervical blocks for both groups.
• Pain was assessed using a 100-mm visual analog scale (VAS) immediately post-abortion.

Main Results:

• 39 women were enrolled; 19 received nitrous oxide and 20 received IV sedation.
• 36.8% of women in the nitrous oxide group required conversion to IV sedation due to inadequate pain control.
• Women receiving IV sedation reported significantly lower VAS pain scores (mean difference 20.1 mm) compared to those receiving nitrous oxide.

Conclusions:

• Intravenous sedation is more effective than inhaled nitrous oxide for pain control during second-trimester surgical abortions.
• The study demonstrated that inhaled nitrous oxide was not noninferior to IV sedation for this indication.