Propofol infusion during regional anesthesia: sedative, amnestic, and anxiolytic properties

We examined the plasma concentrations and resultant clinical effects produced by four different propofol bolus infusion regimens in 98 healthy males undergoing elective urologic procedures under regional anesthesia. Patients were randomly assigned to one of four propofol dosage groups. In Groups 1-4, loading doses of propofol equal to 0.2, 0.4, 0.5, or 0.7 mg/kg intravenously, respectively, were followed by fixed-rate propofol infusions of 0.5, 1, 2, or 4 mg.kg-1.h-1, respectively, during the regional block procedure. Sedation (sleepiness) was assessed independently by the patient and a blinded observer using 100-mm visual analog scales. Intraoperative amnesia was assessed using picture recall. Sedation scores increased in a dose-dependent fashion (13 +/- 19, 21 +/- 19, 45 +/- 28, and 73 +/- 26 mm at 30 min in Groups 1-4, respectively). Within a given dosage group, sedation scores were stable during the maintenance infusion period. Mean plasma propofol concentrations increased with higher propofol infusion rates (0.16 +/- 0.3, 0.18 +/- 0.1, 0.47 +/- 0.2, and 1.1 +/- 0.8 microgram/mL at 30 min in Groups 1-4, respectively). However, significant variability was observed among individual patient sedation scores and plasma propofol concentrations. Anxiety scores decreased in all four propofol infusion groups during the maintenance period. Hemodynamic variables and hemoglobin oxygen saturation values were similar in all four treatment groups. Recovery from propofol's central effects was rapid after discontinuation of the propofol infusion, and the incidence of side effects was low. Recall of intraoperative events was more commonly observed in the lower-dosage groups (86%, 96%, 58%, and 13% of patients in Groups 1-4, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)