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Top1. Introduction
A major issue in post-operative control is the patient’s hypertension. It is important to maintain the patient’s physiological parameters prior to and post-medical treatments (Araki & Furutani, 2005). The most significant physiological parameter is blood pressure, which can be controlled via drug infusion. This is not a trivial task as one has to titrate the drug accurately with proper knowledge of the dynamics of the process. The lack of accuracy and timely infusion of the drug may lead to fluctuations in the blood pressure level. This causes pernicious oscillations in the blood pressure level leading to either hypertension or shock (Bailey & Haddad, 2005). The most widely used drug for the control of Mean Arterial Blood Pressure (MABP) is anti-hypertensive Sodium Nitroprusside (SNP) and for Cardiac Output (CO) is Dopamine (DPM) (Behbehani & Cross, 1991). Dopamine (DPM) is the potent vasopressor agent used for critically ill patients in Intensive Care Unit (ICU), Intensive Cardiac Care Unit (ICCU), Surgical Intensive Care Unit (SICU), Medical Intensive Care Unit (MICU) etc. The onset of action starts within five minutes of Intravenous (IV) administration of DPM. In present scenario dosage of DPM is as per lean body weight (Holmes et al., 2005; Geremia et al., 2012). Immediate infusion rates, i.e. 2 to 5 
and 5 to 15 
cause direct stimulation and increase in Mean Arterial Blood Pressure (MABP) and Cardiac Output (CO). Certain researchers (Cheng et al., 2019; Tufano et al., 2010) have studied the comparative efficacy of vasoactive medication suggesting the use of other inotropic agents such as Nor-epinephrine and Dobutamine. Though there are other inotropic agents available for CO control in acute heart failure syndrome, DPM still remains an essential drug in the patients of septic shock and it is used as the first-line vasopressor in hypertensive emergencies. Epidemiological studies focusing on temporal trends in ICU (Thongprayoon et al., 2016) also revealed that DPM was used in 14% cases in SICU and 50% cases in ICCU over a span of seven years.
Sodium Nitroprusside, a potent vasodilator, is used extensively in the treatment of hypertensive emergencies due to its favourable pharmacokinetic parameters and immediate onset of action (duration 1 to 2 minutes). Recent literature (Benken, 2018) has stated that the dosage of IV infusion, i.e. 0.25 to 10 
titration by 0.1 to 0.2 
results in a significant decrease in MABP. A study (Mullens et al., 2008) has also concluded that SNP vasodilatation has favourable long term clinical outcomes and it remains an excellent therapeutic choice.
In current Indian scenario of government and private setups, Med captain’s infusion syringe pumps are most commonly used in ICU and ICCU for injectable vasopressors and vasodilators and the fluctuations in physiological parameters are mostly monitored on Philips IntelliVue MP5. Looking at the importance of DPM and SNP in control of MABP and CO in cardiac patients, the lack of automatic control for the simultaneous regulation of MABP and CO may lead to increase in the time spent by ICU nurses in attending the cardiac patient for monitoring blood pressure. According to a survey (Bequette, 2013), 73% of the myocardial revascularization patients suffer from post-operative hypertension and require control of blood pressure. The same survey revealed that the Intensive Care Unit (ICU) nurses spend 26% of their time in attending the hypertensive patient post-operation for monitoring blood pressure. Thus, open-loop manual control may lead to a tedious job for the ICU personnel. On the other hand, the development of an automatic closed-loop control unit can provide timely and desirable performance with accuracy. Moreover, the automated closed-loop system controls primary variables and also monitors secondary variables for diagnostics. That allows the physician to spend more time monitoring the patient for conditions that are not easily measured and keeps the physician always ‘in the loop’ (Rao et al., 1999). Thus, closed-loop automatic control may lead to a reduced attendance time for the nursing staff as well as the physicians and surgeons.