[Reliability of propofol target-controlled infusion in obese patients].

Background: Propofol target-controlled infusion (TCI) is now commonly used for induction and maintenance of anesthesia. In this study, we measured the propofol plasma concentrations in obese patients in order to test our hypothesis that propofol TCI is reliable for use in obese patients.

Methods: We measured plasma concentrations of propofol in 10 obese patients undergoing elective general anesthesia. Propofol TCI was commenced at a target plasma concentration of 4microg x ml(-1) using a TCI pump. The target concentration was kept at 4microg x ml(-1) for at least 3 hours. Arterial blood samples were drawn for measurement of the propofol plasma-concentration analysis at 30, 60, 90, 120 and 180 minutes after the induction of anesthesia, and at the emergence from anesthesia.

Results: The measured plasma concentrations of the drug were not significantly different from the target plasma concentrations and they showed no tendency to increase during the 3 hours of anesthesia. The measured plasma concentration at emergence was lower than the estimated value.

Conclusions: We conclude that propofol TCI is a reliable method for maintaining anesthesia even in obese patients. At emergence, however, the data suggested that the plasma concentrations might be lower than the estimated values in obese patients.