Sole use of dexmedetomidine has limited utility for conscious sedation during outpatient colonoscopy

This study evaluated the ability of dexmedetomidine to provide analgesia and sedation for outpatient colonoscopy, examining outcomes including cardiorespiratory variables, side effects, and discharge readiness. Sixty-four patients were randomly assigned to one of three treatment regimens. In group D, patients received 1 microg/kg dexmedetomidine over 15 min followed by an infusion of 0.2 microg x kg x h. Group P received meperidine (1 mg/kg) with midazolam (0.05 mg/kg), and group F received fentanyl (0.1-0.2 mg intravenous) on demand. The assessment included measurements of heart rate, blood pressure, oxygen saturation, respiratory rate, quality of sedation/analgesia, and an evaluation of the recovery time. The study was terminated before the planned 90 patients had been recruited because of adverse events in group D. In all groups, negligible hemoglobin oxygen saturation and respiratory rate variations were observed. In group D, there was a significantly larger decrease in heart rate (to approximately 40 beats/min in 2 of 19 cases) and blood pressure (to less than 50% of the initial value in 4 of 19 patients). Supplemental fentanyl was required in 47% of patients receiving dexmedetomidine to achieve a satisfactory level of analgesia (vs. 42.8% of patients in group P and 79.2% of patients in group F). Vertigo (5 patients), nausea/vomiting (5 patients), and ventricular bigeminy (1 patient) were observed only in group D. Time to home readiness was longest in group D (85 +/- 74, 39 +/- 21, and 32 +/- 13 min in groups D, P and F, respectively; P = 0.007). The use of dexmedetomidine to provide analgesia/sedation for colonoscopy is limited by distressing side effects, pronounced hemodynamic instability, prolonged recovery, and a complicated administration regimen.