In Vivo Performance Evaluation of an FOPID Controller for Closed-Loop Anesthesia

In this article, we design and evaluate a fractional-order proportional-integral-derivative (FOPID) controller for the regulation of total intravenous anesthesia (TIVA). In particular, the FOPID controller has been designed to regulate the patient’s depth of hypnosis (DoH), measured via the bispectral index (BIS) monitor, by coadministrating both the hypnotic and analgesic drugs used in TIVA. Separate tunings are obtained for the induction phase and for the maintenance phase. For the former, a methodology based on the minimization of the integrated absolute error (IAE) has been employed, while for the latter, the isodamping design approach has been applied. Experiments carried out on ten patients undergoing plastic surgery show that the FOPID controller meets the clinical requirements for each one of the ten patients without requiring any manual intervention from the anesthesiologist. Notably, the controller provided a fast rejection of disturbances without provoking harmful overdosing episodes.