pital and the acquisition of written informed consent, eight patients scheduled to undergo an elective A-V shunt construction in the forearm received propofol PCS. All patients were premedicated with atropine sulfate 0.01 mg·kg Ϫ1 intramuscularly 30 min before arrival at the operating room. After the placement of routine monitors (ECG, NIBP, and a pulse oximeter for arterial hemoglobin oxygen saturation [Sp O 2 ]), axillary blockade was performed by the standard approach, with an injection of 20 ml of 1.5% lidocaine with epinephrine 5 µg/ml.The PCS setting consisted of 0.2 mg·kg Ϫ1 of propofol with a lockout interval of 3 min. The basal infusion used was 2 mg·kg·h Ϫ1 following a 0.4 mg·kg Ϫ1 bolus injection. All patients were shown how to use the device and were instructed to use the pump (Baxter AP-II PCA pump; Baxter, Chicago, IL, USA) if they felt anxious or wished to be more sedated during their operation.The cardiorespiratory condition (blood pressure [BP], heart rate [HR], respiratory rate, arterial blood gas analysis) was recorded during the surgical procedure. The degree of sedation was assessed at 1, 15, 30, and 60 min after the loading dose and 15 min after the end of PCS. The level of sedation was assessed by a fivepoint scale: 1, fully awake; 2, drowsy; 3, eyes closed, but arousable by command; 4, eyes closed, but arousable by mild physical stimulation; and 5, eyes closed and nonarousable by mild physical stimulation [5]. A sedation score of 4 or more was considered to be oversedation in this study. To collect arterial blood for the analysis of arterial blood gas and the plasma propofol level, an arterial catheter was inserted into the right dorsal is pedis artery. Arterial blood gas analysis was performed before the start of PCS as a control value. For the analysis of plasma propofol levels, blood was collected in tubes containing ethylene diamine tetraacetic acid (EDTA) at 1, 15, 30, and 60 min after the start of PCS and 15 min after the end of PCS. Each sample was then centrifuged at 1500 g for 15 min and