Safety and Efficacy of Dexmedetomidine in Painless Colonoscopy

104 patients who undergo painless colonoscopy from Decemenber 1,2019 to June 30,2022 will be randomized to two groups: propofol group and dexmedetomidine group.

In the dexmedetomidine group,dexmedetomidine was infusion intravenously with a loading dose of 0.5 μg kg-1 for 10 min, then infusion at 0.3 μg kg-1 h-1 according to the ideal body weight of the patient until the end of colonoscopy. In the propofol group, Propofol was administrated 1 mg kg-1 intravenously, then titrated given by 0.5 mg kg-1.For all patients, if Ramsay sedation scale score reached 3, colonoscope was inserted. During the whole process, maintenance Ramsay score of 3 to 4. Propofol 10 mg was administrated as the rescue dose if body movement occurred during colonoscopy

The primary outcome was the occurrence of hypotension. Secondary outcomes included the followings:(1) the duration and the maximum decreasing in BP. The time-weighted average which is measured by calculating the area under the threshold (AUT) divided by the total duration of colonoscopy. AUT = (depth of hypotension below a 20% decrease in systolic blood pressure or diastolic blood pressure from pre-procedure baseline or SBP of 90 mm Hg or DBP of 50 mm Hg× time in minutes spent of hypotension); (2) the incidence of bradycardia and hypoxemia, mask-assisted ventilation and body movement；(3) the discharge time , patients and endoscopists satisfaction score.

Inclusion criteria

• Patients aged above 18 years
• American Society of Anesthesiologists (ASA) physical status of 1-2
• Patients scheduled for sedation colonoscopy

Exclusion criteria

• Emergency patients
• Body weight < 40 kg or >100 kg
• Allergy to dexmedetomidine, propofol in this trail, a previous adverse reaction to dexmedetomidine or propofol
• Pregnancy or lactation
• Drug abusers
• Participation in other clinical studies within the previous 3 months