A sphygmomanometer is an instrument used to measure blood pressure. The word is derived from the Greek sphygmus (pulse) plus the scientific (physical) term manometer.
Arterial blood pressure is the force of pressure, which the blood is exerting on the walls of the blood vessels in which it flows. The blood pressure in the artery varies during the cardiac cycle. The cardiac cycle is defined as the cycle of events that take place during one systole and diastole of the heart. Systole refers to contraction and diastole the relaxation. During ventricular systole, when the left ventricle is forcing blood into the aorta the pressure rises to a peak which is referred to as systolic pressure. During diastole the pressure falls and the lowest value reached is referred to as diastolic pressure.
The blood pressure depends partly on the force and volume of blood pumped by the heart and partly on the contraction of the muscles in the walls of the arterioles. Blood pressure changes during physical exercise, during anxiety and emotion and in sleep etc. However a prolonged or constant elevation of blood pressure, a condition known as hypertension can increase a person's risk for heart attack, stroke, heart and kidney failure and other health problems. It is always suitable to measure blood pressure when a person is in a relaxed and in resting condition.
The normal blood pressure value is 120/80mm Hg, in which ' 120' denotes the systolic pressure and 80 the diastolic pressure.
There are two types of sphygmomanometer viz., Monometric type and 2. Digital (modern) type.
1. Sphygmomanometer helps to estimate the state of blood circulation and the working of heart.
2. Sphygmomanometer helps to diagnose pathological conditions such as hypertension (increased BP) and hypotension (reduction in BP).