Closed-loop control of anesthesia using two-degrees-of-freedom control with a target-controlled infusion algorithm

This article proposes a new closed-loop control method to induce and maintain a desired depth of hypnosis during total intravenous anesthesia. The method utilizes two-degrees-of-freedom control, with propofol infusion rate as the input and bispectral index (BIS) as the output. A target-controlled infusion (TCI) algorithm called STANPUMP is used as the feedforward action to achieve the desired BIS response, and a feedback controller based on a Kalman filter deals with model uncertainties. Adding a TCI algorithm as the feedforward action improves the time-to-target and enhances patient safety. This is because it allows for a seamless transition to open-loop control if needed.