Determination of the median effective dose of dexmedetomidine for the prevention of emergence agitation in geriatric patients undergoing major open surgery with general anesthesia: A prospective, double-blinded, dose-response trial

Abstract BackgroundDexmedetomidine can effectively decrease the incidences of emergence agitation (EA) in adult patients, but there are major side effects related to increased dose of dexmedetomidine. The purpose of this study was to determine of the median effective dose of dexmedetomidine in the prevention of EA among geriatric patients undergoing major open surgery with general anesthesia.MethodsA total of 50 geriatric patients were enrolled in this study. Dexmedetomidine 0.5µg·kg-1·h-1 continuous intravenous infusion was administered to the first patient. The next dose was increased or decreased by 0.05 depending on the response of the previous patient, according to the Dixon up-and-down method. An “effective” or “ineffective” response was determined based on the Riker sedation-agitation score(RSAS), we defined “effective” as RSAS < 5, and “ineffective” as RSAS ≥ 5.ResultsThe ED50 of dexmedetomidine in prevention of EA was 0.30µg·kg-1·h-1 (95% CI, 0.27–0.33) and the predicted ED95 was 0.42µg·kg-1·h-1(95% CI, 0.38–0.51). The incidence of bradycardia was significant increased in group without EA compared to the group with EA (57.1% vs 13.6%, P = 0.002).ConclusionsThe ED50 of dexmedetomidine in prevention of EA was 0.30µg·kg-1·h-1 (95% CI, 0.27–0.33) and the predicted ED95 was 0.42µg·kg-1·h-1 (95% CI, 0.38–0.51). Bradycardia was the main complication.Trial registrationThis study was registered in the Chinese Clinical Trial Registry (Registration number: ChiCTR1900023769) on June 11th, 2019.