Ketamine Compared With Fentanyl for Surgical Abortion: A Randomized Controlled Trial.

Abstract

To compare patient satisfaction with anesthesia after first-trimester surgical abortion among patients receiving intravenous (IV) ketamine compared with IV fentanyl for procedural sedation. This was a randomized noninferiority trial comparing IV ketamine to IV fentanyl for first-trimester surgical abortion up to 13 6/7 weeks of gestation. Patients were randomized to receive either ketamine 200-500 micrograms/kg IV over 2 minutes, repeated every 5 minutes until appropriate analgesia was achieved, or fentanyl 0.5-1 micrograms/kg IV over 2 minutes, repeated every 5 minutes until appropriate analgesia was achieved. All patients received midazolam 2 mg IV. The primary outcome, patient satisfaction, was measured using the Iowa Satisfaction with Anesthesia Scale immediately postprocedure. Secondary outcomes included postoperative pain, additional pain medication necessary during the procedure and on discharge, physician satisfaction, and time to discharge. We calculated a sample size of 84 with a noninferiority margin of 0.6 on the Iowa Satisfaction with Anesthesia Scale with 80% power, one-sided type 1 error of 0.025, and further increased this number to 110 to account for potential dropout. From April to October 2021, 184 patients were screened and 110 were randomized (57 to ketamine and 53 to fentanyl). Demographics were similar between groups. The primary outcome, patient satisfaction with anesthesia, was noninferior in the ketamine group (mean score 2.4, SD 0.8) as compared with the fentanyl group (mean score 2.2, SD 0.9) with a risk difference of 0.20 (95% CI 0.11-0.52). More hallucinations were reported in the ketamine group. Otherwise, secondary outcomes were similar between the groups. Compared with IV fentanyl, IV ketamine is noninferior for patient satisfaction with anesthesia when used for procedural sedation for first-trimester outpatient surgical abortion. ClinicalTrials.gov , NCT04871425.