The control of physiological variables presents specific challenges, mainly due to the highly nonlinear, complex behavior of biological systems. Cardiovascular system stands as a clear example, with critical situations when control is desirable and troublesome in the same time. This paper presents a fuzzy control strategy for blood pressure by automatic infusion of two commonly used drugs, sodium nitroprusside and dopamine respectively. The Mean Arterial Pressure (MAP) is regulated using the Zeigler-Nichols Proportional-Integral and Fuzzy logic controllers (FLC). Simulations study demonstrates the ability of FLC regulates MAP at a nominal and safe value within a reasonable time period. Furthermore, cost reduction by minimized drug consumption and shortened period of clinical treatment is part of the main issues which motivates automation. Performances of control techniques are evaluated based on integral square error and integral absolute error. From the simulation results and from the performance criteria it is observed that FLC controls MAP better than that of conventional PI controller.
