Patients in Group 1 will receive remifentanil and ketamine. Remifentanil will be administered initially with a 1mcg/kg IV bolus followed by a continuous infusion, 0.1 to 0.15 mcg/kg/min IV (using ideal body weight) with titration to a maximum dose of 0.2 to 0.4 mcg/kg/min IV. Total dose of ketamine will be titrated from 10 to 40 mg, based on clinical judgment, and it will be recorded. Ketamine will be delivered using 2mL syringes, previously filled with ketamine in normal saline at a 10mg/mL concentration.

The patients in this group will receive fentanyl doses that range between 0.5 to 2 mcg/kg (25 - 50 mcg) IV bolus in combination with midazolam 1-5 mg bolus over at least 2 minutes as determined by attending anesthesiologist (not to exceed 2.5 mg / 2 min per package insert). Total dosing of fentanyl and midazolam may be titrated, based on clinical judgment, and it will be recorded. Maintenance, additional midazolam doses of 25% of total initial dose required to achieved desired sedation may be administered IV if additional sedation is considered necessary

Opioid analgesic

The primary outcome will be a difference in patient satisfaction with sedation, as determined by a 5-point difference in the PSSI questionnaire. The total score will be assessed by summing the responses to each question. In the scale, 0 will denote no satisfaction (worst outcome) and 100 will represent the greatest possible satisfaction (best outcome).

Difference between both groups in terms of numerical rating scale (NRS) for discomfort associated with the procedure (as reported by the patient). In the scale, 0 will denote no discomfort (best outcome) and 5 will represent the greatest possible discomfort (worse outcome).