Randomized Controlled Trial of Ketamine and Moderate Sedation for Outpatient Endoscopy in Adults

Introduction: Ketamine is an effective sedative agent in a variety of settings due to its desirable properties including preservation of laryngeal reflexes and lack of cardiovascular depression. We hypothesized that ketamine is an effective alternative to standard moderate sedation (SMS) regimens for patients undergoing endoscopy.

Materials and methods: We conducted a randomized controlled trial comparing ketamine to SMS for outpatient colonoscopy or esophagogastroduodenoscopy at Brooke Army Medical Center. The ketamine group received a 1-mg dose of midazolam along with ketamine, whereas the SMS group received midazolam/fentanyl. The primary outcome was patient satisfaction measured using the Patient Satisfaction in Sedation Instrument, and secondary outcomes included changes in hemodynamics, time to sedation onset and recovery, and total medication doses.

Results: Thirty-three subjects were enrolled in each group. Baseline characteristics were similar. Endoscopies were performed for both diagnostic and screening purposes. Ketamine was superior in the overall sedation experience and in all analyzed categories compared to the SMS group (P = .0096). Sedation onset times and procedure times were similar among groups. The median ketamine dose was 75 mg. The median fentanyl and midazolam doses were 150 mcg and 5 mg, respectively, in SMS. Vital signs remained significantly closer to the physiological baseline in the ketamine group (P = .004). Recovery times were no different between the groups, and no adverse reactions were encountered.

Conclusions: Ketamine is preferred by patients, preserves hemodynamics better than SMS, and can be safely administered by endoscopists. Data suggest that ketamine is a safe and effective sedation option for patients undergoing esophagogastroduodenoscopy or colonoscopy (clinicaltrials.gov NCT03461718).