A Decoupled Fractional Order Control Strategy to Increase Patient Safety During Anesthesia-Hemodynamic Interactions

Monitoring and control of general anesthesia, involving cardiac output or mean arterial pressure are critical to ensure patient safety during surgery. Several computer control solutions have been developed for each of the anesthesia components and hemodynamic processes. However, most do not tackle the synergistic and antagonistic effects of the anesthetic and hemodynamic drugs. Hitherto, only a handful of preliminary results and ideas regarding multivariable control have been reported so far, usually considering a simplified decentralized approach. A decoupled control strategy is proposed here to reduce the interaction between the hemodynamic and anesthesia sub-systems, hence increasing the robustness and stability of the overall control loop. Due to their intrinsic robustness to uncertainty and process model variability, fractional order controllers are designed to ensure that more specific performance criteria are addressed, compared to the traditional PIDs. The decoupled control strategy is compared to the decentralized approach to validate the minimization of the interactions. A robustness analysis is performed using a benchmark patient model and data from 24 patients.