### Literature Review  
#### 1.1.1 The Physiological Parameters for Health Status Determination  
Vital signs have been widely used as performance indicators of a person's health. The four main vital signs that are routinely monitored by health care providers are body temperature, pulse rate/heart rate, respiration rate (rate of breathing), blood pressure (non-invasive systolic) [15; 16]. The normal body temperature of a person varies depending on the gender, any recent activities that the person has been engaged in, along with food and fluid consumption, the time of the day, and in women, the stage of the menstrual cycle. The pulse rate is a measure of the heart rate, or the heart beats per minute. As the heart pumps blood in and out of the body, this action puts pressure on the arteries, which could be felt as a pulse. Taking a pulse on the wrist measures the heart rate and can indicate heart rhythm and health. The normal pulse for healthy adults ranges from 60 to 100 beats per minute. The pulse rate can fluctuate, and it may increase with exercise, illness, injury, and emotions. The heart rate and pulse rate are technically different, though it is the heart beats that cause the pulse, so for analytical purposes, the heart rate can be used just as effectively as the pulse rate. Pulse rate, however, can use used in heart rate variability measurement [17]. The respiration rate is the number of breaths taken by a person per minute. It is usually measured when a person is at rest, sometimes in a supine position, and it simply involves counting the number of breaths for one minute. Respiration rates also vary, and can it increase with fever, sickness, and with other medical conditions that influence respiration. The normal respiration rates for an adult person in resting position range from 12 to 20 breaths per minute, and may depend on age. Traditionally, in intensive care units and ambulatory settings, a spirometer has been used to measure the respiration rate; however, there has been a range of modern respiration rate sensing devices that have emerged, even in the consumer market, which are non-invasive in nature [9]. This research uses the ECG signal to calculate the respiratory rate, also called the ECG-derived respiratory (EDR) rate. Thus, all of the sensors mentioned in this research are ubiquitous, wearable, and accurate, as compared to the traditionally used sensing devices and manual interventions [18]. Blood pressure is the force of the blood pressurizing the artery walls during the contraction and relaxation of the heart. Each time the heart beats, it pumps blood into the arteries, resulting in an increase and peak in blood pressure as the heart contracts, and when the heart relaxes, the blood pressure falls. Two measures have been traditionally recorded when measuring blood pressure using an instrument called sphygmomanometer. The higher measure, called the systolic pressure, refers to the arterial pressure when the heart contracts and pumps blood through the body. The lower measure, called the diastolic pressure, refers to the arterial pressure due to the heart when it comes to rest and is filled with blood. Both the systolic and diastolic pressures are recorded as \"mm Hg\" (millimeters of mercury). The research revolves around using modern state-of-the-art measuring methods, and this means that blood pressure is a vital sign [19]. High blood pressure (or hypertension) increases the risk of cardiac arrest, heart failure, and stroke, and its measurement is used as an important vital sign. Blood pressure can be categorized as normal, elevated, or stage 1 or stage 2 high blood pressure: Normal blood pressure is a systolic pressure of less than 120, and a diastolic pressure of less than 80, which is generally recorded as 120/80. Elevated blood pressure is systolic pressure with a range of 120 to 129, and diastolic pressure of less than 80.