Comparison of propofol administration techniques for sedation during monitored anesthesia care

Sixty-three outpatients undergoing breast biopsy procedures with local anesthesia were randomly assigned to receive propofol by intermittent bolus injections (n = 21), a conventional syringe infusion pump (n = 21), or a target-controlled infusion (TCI) device (n = 21) for intraoperative sedation. In the first two groups, an initial intravenous (IV) bolus of propofol (0.3 mg/kg) was administered and an attempt was made to maintain the sedation level at an Observer's Assessment of Alertness/Sedation (OAA/S) score of 3 or 4 with either intermittent bolus injections of propofol (10 mg) or a variable-rate infusion (25-100 micrograms.kg-1.min-1). In the TCI group, the initial target concentration of propofol was set at 2 micrograms/mL and the target concentration was adjusted between 1 and 4 micrograms/mL in an attempt to maintain an OAA/S score of 3 or 4. Recovery was assessed using clinical criteria, visual analog scales (VAS), and the digit-symbol substitution test (DSST). The overall quality of sedation, operating conditions, and clinical recovery profiles were similar in all three treatment groups. The anesthesiologist had to intervene more frequently in the intermittent bolus injection group than in the two infusion groups. We conclude that the use of an infusion technique may allow the anesthesiologist more time for monitoring the patient by decreasing the number of interventions necessary to administer supplemental doses of the sedative medication during the operation. However, the cost of the IV drug delivery system may become an increasingly important factor in the future.