A Computerized Drug Delivery Control System for Regulation of Blood Pressure

Many patients presenting hypertension before/after surgery should need to receive adequate medication. For example, patients with dissecting aneurysm often show extreme hypertension and an adequate control of blood pressure of the patient will lead to good surgical outcome. On the other hand, untreated hypertension after surgery may create complication. Therefore, hypertension control after/before surgery is important. In this paper, postsurgical hypertension control for cardiac patients, without loss of generality, will be focused. From the past experience, elevated blood pressure often occurs in the early hours following open-heart surgery. Basically, there are several medications such as Sodium Nitroprusside (SNP) and Nitroglycerin, etc., which are commonly used for the treatment of postsurgical hypertension of the cardiac patient. We consider here Sodium Nitroprusside in the design of the control system. However, due to a wide range of patients’ drug sensitivities to SNP, manual control by clinical personnel could be very tedious, time consuming and inconsistent. An automatic drug delivery controller based on feedback method may quickly reduce the oscillatory change in mean blood pressure through infusion of SNP. In this paper, an adaptive Proportional-Integral (PI) control of mean blood pressure using SNP is presented. A new algorithm updating variations in time delay and sensitivity of the system is proposed and its effectiveness in the treatment of the hypertension patient is discussed. For demonstration, simulations under clinical conditions are carried out.