Conscious Sedation for Outpatient Colonoscopy

Eighty patients undergoing outpatient colonoscopy will be randomized into two equal groups. In Dexmedetomidine (DEX) group the patients will be administered a loading dose of i.v. dexmedetomidine 1 μg/kg over 10 min, followed by a continuous infusion of 0.2-1 μg/kg/h, titrated according to the sedation score, till the end of the procedure. In the PR group, propofol will be started by a loading dose of 0.5 mg/kg over 3-5 minutes then a maintenance infusion of 25-75 μg kg/min. Remifentanil infusion will be started at 1 μg kg over one minute then and 0.01-0.1 μg kg/min. If the patient complained of pain or discomfort, the infusion rates of dexmedetomidine (DEX group) or propofol-remifentanil (P-R group) will be increased. If the higher limit of the dose range of the study drugs reached, additional fentanyl 0.5 μg/kg i.v. boluses will be administered. Rescue medication consisting of propofol boluses of 0.5 mg/kg i.v. will be given if the previous protocol failed. Sedation score,haemodynamics, end-tidal carbon dioxide, oxygen saturation, total fentanyl, propofol bolus doses, patient and colonoscopist satisfaction and side effects will be recorded.

Inclusion criteria

• ASA I or II physical status
• 18-65 years
• Scheduled for elective colonoscopy

Exclusion criteria

• History of allergy to any of the study drugs
• Alcohol or drug abuse.
• Second and third-degree heart block.
• Morbid obesity.
• Pregnant and lactating women.
• Psychiatric disorders.
• Severe cardiac, respiratory, renal, and liver diseases