BACKGROUND: The aim of this study was to examine the safety and efficacy of patient-controlled sedation (PCS) according to the lock-out time (LOT, 1 or 2 min) with a demand bolus of propofol and alfentanil fixed during a colonofiberscopy.

METHODS: Fifty ASA physical status 1 or 2 patients who underwent a colonofiberscopy were enrolled in this study. They were provided with a PCS pump (Perfusor(R) fm, B Braun Germany, nominal infusion rate, NIR = 1,000 ml/h) containing propofol (9.1 mg/ml) and alfentanil (45.5µg/ml) in order to self-administer a 2 ml bolus whenever they felt uncomfortable. The lock-out time (LOT) was set to 1 (n = 20, group 1) or 2 (n = 30, group 2) minutes. The Observer's Alertness/Sedation (OAA/S) score, D/A (delivery/attempt, %), blood pressure, heart rate, respiratory rate, SpO2, end tidal CO2 and bispectral index (BIS) were assessed and measured during and/or after the procedures. The verbal descriptive pain scores, as well as the patient's and endoscopist's satisfaction scale were assessed after the procedures.

RESULTS: Intraoperative and postoperative pain scores, D/A, the patient's and endoscopist's satisfaction were similar in both groups. However, the lowest BIS values in group 1 was lower than in group 2 (70.3 ± 12.2 and 77.6 ± 6.8, respectively, P = 0.010). There were fewer patients whose lowest OAA/S score was <3 in group 2 (4/30) than in group 1 (11/20)(P = 0.002).

CONCLUSIONS: With a demand bolus of propofol (18.2 mg) and alfentanil (91.0µg) fixed, the incidence of over-sedation was higher at LOT 1 min than at LOT 2 min while the efficacy was similar in the PCS with a high NIR during the colonofiberscopy.