Abstract| Volume 116, P82, December 2022

P038Ketamine versus fentanyl for surgical abortions: A randomized noninferiority trial

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      To compare patient satisfaction with anesthesia after first-trimester surgical abortions among patients receiving intravenous ketamine vs. IV fentanyl for procedural sedation.


      This was a randomized noninferiority trial comparing IV ketamine to IV fentanyl for surgical abortions up to 13 6/7 weeks’ gestation. Patients were randomized to receive midazolam 2 mg IV  and either ketamine 200–500 mcg/kg IV over two minutes, repeated every five minutes until appropriate analgesia was achieved, or fentanyl 0.5–1 mcg/kg IV over two minutes, repeated every five minutes until appropriate analgesia was achieved. The primary outcome, patient satisfaction, was measured using the Iowa Satisfaction with Anesthesia Scale (ISAS) immediately post-procedure. Secondary outcomes included postoperative pain and additional pain medication given. We calculated a sample size of 84 with a noninferiority margin of 0.6 on the ISAS 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) 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). 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 surgical abortions.
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