Development of ConGraseTCI, a MacOS Application for Target-Controlled Infusion of Propofol

Osamu Nagata, M.D., Ph.D., Haruko Fujiwara, M.D., Mieko Chinzei, M.D., Ph.D., Megumi Tagami, M.D., Ph.D., Kazuo Hanaoka, M.D., Ph.D.

Department of Anesthesiology, Faculty of Medicine, The University of Tokyo

ConGraseTCI is an application software developed by our group with CodeWarrior Professional Release 5 (Metrowerks Inc., U.S.A.) in C++ language. It runs on Macintosh/PowerMacintosh (Apple Computer Inc., U.S.A.) computer, and controls a Graseby 3500 (Graseby Inc., U.K.) syringe pump connected with a null modem through the computer’s serial port. It manages two types of target–controlled infusion (TCI) of propofol, i.e., TCI for blood compartment and TCI for effect-site compartment. The predicted blood concentration and effect–site concentration are calculated by the Runge-Kutta method using the same pharmacokinetic/pharmacodynamic microconstants used in Duprifusor. To achieve optimal control for TCI, we selected an original pharmaco-kinetic/pharmaco-dynamic algorithm developed by our group instead of the PID (Proportional-Integral-Differential) algorithm.

ConGraseTCI has two advantages over Duprifusor: it can calculate both the effect-site concentration of propofol and the predicted wake-up time. The predicted wake-up time is calculated as the interval during which the drug concentration decreases to the level at which the patient regains consciousness. Though the context-sensitive half-time is used to explain the intervals of drug effects, it is not so useful in clinical anesthesia because it can give us little information on the amount of time we have to wait for the patient to wake up after stopping the drug infusion. Compared to the context-sensitive half time, the wake-up time tells us the interval until consciousness is regained.

Unfortunately, there is no commercial TCI-system in Japan at this moment. ConGraseTCI was distributed as freeware at the 45^th annual meeting of the Japan Society for Anesthesiologists, and now it is used in more than 20 hospitals in Japan. This software can be downloaded from the Internet at :

http://www.u-page.so-net.ne.jp/fa2/o-nagata/ Freeware_j.html