Today, automatic control plays an important role in modern medicine. Applications of control in medicine include insulin injection systems, respiratory control, artificial heart and control of artificial limbs. Other important and vital applications can be mentioned. Control in medicine is the control of blood pressure. Simply put, blood pressure is proportional to cardiac output and vascular resistance, so to reduce blood pressure in hypertension, cardiac output or vascular resistance can be reduced. The usual way to lower blood pressure is to reduce vascular resistance by injecting vasodilators.The antihypertensive drug used in this dissertation is sodium nitroprusside, which lowers blood pressure by inhibiting nerve messages from the sympathetic and parasympathetic nodes. It can be said that one of the most important factors in surgery is blood pressure control.