Cost-effectiveness of closed-loop versus open-loop infusion of propofol guided by bispectral index in elderly patients undergoing abdominal surgery

Objective To compare the cost-effectiveness of closed-loop versus open-loop infusion of propofol guided by bispectral index (BIS) in elderly patients undergoing abdominal surgery. Methods Sixty American Society of Anesthesiologists physical status Ⅱpatients of either sex, aged 65-75 yr, with body mass index of 18-25 kg/m2, undergoing elective open gastrointestinal tumor resection with general anesthesia, were allocated into closed-loop target-controlled infusion (TCI) group (group C) and open-loop TCI group (group O) using a random number table.Propofol was given using closed-loop TCI, and the target BIS value was set at 45-55 in group C. In group O, the target plasma concentration (2.0-3.5 μg/ml) of propofol was adjusted to maintain the BIS value at 45-55.Remifentanil was given by TCI with the target plasma concentration of 2-8 ng/ml in both groups.The total consumption of propofol and remifentanil, time rate of maintaining BIS value within the target range, development of intraoperative hypertension and hypotension, emergence time, tracheal extubation time, time for recovery of orientation, first ambulation time, time to first flatus and length of postoperative hospital stay were recorded.The development of nausea and vomiting and delirium within 3 days after operation and intraoperative awareness was recorded.The cost of anesthetics and total cost of anesthesia were calculated. Results Compared with group O, the total consumption of propofol was significantly decreased, the total consumption of remifentanil was increased, the time rate of maintaining BIS value within the target range was increased, the emergence time, tracheal extubation time and time for recovery of orientation were shortened, the cost of propofol and total cost of anesthesia were decreased (P 0.05). Intraoperative awareness was not found in two groups. Conclusion Compared with open-loop infusion of propofol guided by BIS, closed-loop infusion of propofol guided by BIS is a cost-effective method of anesthesia in elderly patients undergoing abdominal surgery. Key words: Drug delivery systems; Propofol; Electroencephalography; Cost-benefit analysis