Study objective: To compare the sedative, anxiolytic, and amnestic effects, as well as the recovery characteristics, when midazolam (vs. a placebo) is administered to patients receiving a propofol infusion for sedation during local anesthesia.
Design: Randomized, double-blind, placebo-controlled study to evaluate the perioperative effects of intravenous (IV) midazolam.
Setting: Outpatient surgery center of a university-affiliated medical center.
Patients: One hundred thirty-nine consenting, ASA physical status I, II, and III outpatients undergoing elective surgical procedures under local anesthesia.
Interventions: Patients were randomly assigned to receive either midazolam 2 mg IV or saline 2 ml IV prior to injection of local anesthesia. Intraoperative sedation was maintained using a variable-rate propofol infusion.
Measurements and main results: Preoperative assessment of sedation, anxiety, and amnesia was performed before and after IV midazolam. Intraoperative evaluations included level of sedation, as well as cardiovascular and respiratory measurements, at 1- to 5-minute intervals during the operation. Postoperatively, recovery of psychomotor function and patients' subjective feelings were assessed using the visual analog scale and questionnaires. Amnesia was assessed using picture recall during the perioperative period. In the operating room, midazolam 2 mg IV, compared with the placebo, produced a significantly greater increase in patients' level of sedation (7 +/- 13 mm to 49 +/- 21 mm for midazolam vs. 8 +/- 11 mm to 19 +/- 21 mm for the placebo; p less than 0.01) and a greater decrease in anxiety level (62 +/- 25 mm to 21 +/- 21 mm for midazolam vs. 54 +/- 27 mm to 53 +/- 22 mm for the placebo; p less than 0.01). Although the propofol dosage requirements to maintain comparable levels of sedation were similar in both groups, midazolam decreased patients' recall of intraoperative events (e.g., propofol-induced pain on injection and discomfort with local anesthetic injection) without significantly altering cardiorespiratory parameters or prolonging times to ambulation and discharge from the outpatient facility.
Conclusions: Premedication with midazolam 2 mg IV produced increased sedation, amnesia, and anxiolysis when administered immediately prior to the propofol infusion as part of a sedation technique for outpatient surgery. This combination did not prolong the recovery room stay when compared with propofol alone.