Closed Loop Propofol Administration in Pediatric Cardiac Surgery

"In automatic mode, the system requests an update of the BIS data every 5 seconds and calculates the BIS error (difference between the target and actual BIS value). This value along with the trends of BIS in the epoch of the last 30 seconds as well as in the last 5 minutes is passed on to a patient individualized, model based adaptive control algorithm. The algorithm uses the error to calculate an adjustment to the propofol delivery rate, but does not apply it immediately. Adjustments to the propofol delivery rate are only made every 30 seconds, taking into account the sum of previous six BIS error values, the trends of BIS in the epoch of last 30 seconds as well as in the last 5 minutes, time elapsed since the initiation of infusion, pharmacokinetics, the time delay factor between sensing and averaging of BIS data, the time delay factor between the change in infusion rate and the actual change in the plasma concentration of propofol as well as the peak effect of propofol."

"In manual mode, the user can also control the propofol infusion rate manually, using the keyboard or the mouse of the PC. The PC displays a graph of the propofol delivery rate and trend of BIS value."