Abstract: To develop a closedloop feedback controlled volatile anesthesia system with index (BIS) as the control variable and to clinically validate it. MethodsIn the first stage, a closedloop feedback controlled volatile anesthesia system was set up. A volatile anesthetic physiological pharmacokinetics model was built in the system software, whose controlled algorithm was based on the proportional-integral-derivative principle. System software, anesthesia deep monitor, syringe pump and anesthesia machine made up the whole administrate system. In the second stage, enflurane, isoflurane or sevoflurane was used in clinical operations to verify the performance of the administrate system for patients with general surgeries, single side lung venting or obesity. ResultsThe close-loop feedback administrate system can maintain BIS around the target value and retained hemodynamics stabilization. This system reduced the inducement and analepsia time. All patients administrated by this system had not encountered awareness during general anesthesia. ConclusionThe system is able to provide clinically adequate anesthesia using the commonly used volatile anesthetics even when patients′ pharmacokinetics parameters have evident changes.

Key words: Electroencephalography, bispectral index, Feed-back control, Anesthetics, volatile