Switching robust controllers for automatic regulation of postoperative hypertension using vasodilator drug infusion rate*

This paper proposes a new switching robust control algorithm, employing a stable hysteresis switching between neighboring controllers within a set of robust controllers designed for five different operating ranges of the system, for regulating the mean arterial blood pressure (MAP) in postsurgical scenario using infusion of vasodilator drug-Sodium Nitroprusside (SNP). Postoperative hypertension is very critical in patients with cardiac disorder and if it is left untreated, it may lead to adverse consequences. Since the sensitivity to the drug, injection delay and drug fraction recirculating vary among individuals, a robust control algorithm becomes an attractive candidate for regulating MAP in the presence of such parameter uncertainties. In addition, the sensitivity to the drug may even vary with time within the same patient, therefore, it is also treated in the model as time-varying value of the parameter. A stable hysteresis switching between neighboring robust controllers is proposed for larger operating range of the system due to considerably large uncertainty range of the patients’ sensitivity to the drug.