Low-Dose Dexmedetomidine Reduces Median Effective Doses of Propofol Required for Successful Gastroscope Insertion: A...

Patients undergoing painless gastrointestinal endoscopy (GIE) typically receive propofol-based sedation. However, the exact dose of propofol when combined with low-dose dexmedetomidine for this procedure remains unclear. The objective of this study was to determine and compare the median effective doses (ED₅₀, the doses required for successful gastroscope insertion in 50% of the subjects) of propofol when used with low-dose dexmedetomidine (0.3 µg/kg) premedication versus propofol alone during painless GIE.

Adult outpatients aged 18 to 65 years scheduled for GIE were enrolled. Participants were randomized to receive either 0.9% saline (Group S) or 0.3 µg/kg of dexmedetomidine (Group D) intravenously over 5 min before induction with propofol. Using modified Dixon's up-and-down method (MDUDM), the initial induction dose of propofol was 1.5 mg/kg, adjusted in a step size of 0.1 mg/kg. ED₅₀ of propofol required for successful endoscope insertion was calculated by averaging the midpoints of all sequential crossovers. Using isotonic regression analysis, ED₅₀ and ED₉₅ (the effective doses required for successful gastroscope insertion in 95% of the subjects) were then extrapolated. All adverse events during painless GIE were recorded.

Thirty patients were enrolled per group. Using MDUDM, the ED₅₀ of propofol for successful gastroscope insertion was significantly lower in Group D (1.48 ± 0.10 mg/kg) than in Group S (1.82 ± 0.16 mg/kg; P < 0.001). The ED₅₀ and ED₉₅ of propofol were extrapolated to 1.80 mg/kg (83% confidence interval [CI], 1.649-1.882) and 2.10 mg/kg (83% CI, 2.081-2.124) for Group S, respectively, using isotonic regression analysis. These values were significantly lower in Group D, at 1.40 mg/kg (83% CI, 1.297-1.452) and 1.70 mg/kg (83% CI, 1.667-1.753).

Premedication with low-dose dexmedetomidine (0.3 µg/kg) significantly reduces the median effective doses of propofol required for successful gastroscope insertion during painless GIE.