Experimental Evaluation of Analgesia With an Event-Based PID Control Strategy for Anesthesia

The recent introduction of the Conox monitoring system in the clinical practice of total intravenous anesthesia (TIVA) has opened new research opportunities. Indeed, it provides the qCON and the qNOX indexes, which give a measure of hypnosis and analgesia, respectively. This letter presents the first experimental results of closed-loop anesthesia performed by using the Conox monitoring system. In particular, we exploited the qCON as the feedback variable for an event-based PID multiple-input single-output (MISO) controller and we recorded the qNOX to evaluate analgesia. Clinical experiments have been performed on four patients undergoing general anesthesia for elective plastic surgery. The controller demonstrated a satisfactory performance in maintaining qCON within the desired range for all patients. An optimal qNOX level has also been achieved in three out of four cases, while, in one patient, the qNOX level indicated a slight excess of analgesia. These findings suggest that the proposed MISO architecture is effective in providing adequate levels of hypnosis and analgesia and that, in future works, the qNOX information could be leveraged in the controller design to enhance analgesia control.