In 1700s, the physiologists who studied animals knew about the phenomenon of blood pressure (BP). But it was many years before physicians figured out how to measure it in human beings. When the doctors discovered an accurate device called the sphygmomanometer that used a simple procedure for measuring the blood pressure, then onwards it became a necessary element of medical examination. This invention helped in the discovery of hypertension - a wide spread life-threatening disease.

The sphygmomanometer history reads�

� 1863 - Sphygmograph was an early attempt to measure blood pressure. But this method proved to be inaccurate. The instrument had a spring pressed on one end of a lever onto the wrist, compressing an artery. With each pulse wave the lever rose and fell, which was traced by a recording device on a smoked paper.

� 1898 - Sphygmomanometer model had a cuff that was too narrow.

� 1901 - Sphygmomanometer model had a wide cuff but the doctors used their fingers to detect arterial blood flow as they watched for the changes in pressure.

� 1905 � A Russian surgeon, Nikolai Korotkoff, developed the modern technique of using a stethoscope to listen for the sounds of blood flowing through the artery. It was his method that proved to be very accurate and this eventually led to the discovery of hypertension.

� 1920 - A mercury sphygmomanometer was developed

Later based on this model several variations were made to make the use and the blood pressure recording simple like the aneroid sphygmomanometer, digital sphygmomanometer, manual electronic sphygmomanometer, etc.

Blood pressure is measured in the form of two numbers � the systolic blood pressure and the diastolic blood pressure. It is written as 120/80 mm Hg, where 120 is the systolic pressure and 80 is the diastolic pressure. Systolic pressure is the pressure of the blood when the heart muscles contract and this is when the highest pressure exerted by the blood.The diastolic pressure is the pressure of the blood when the heart muscles relax between the beats. This is when the lowest pressure is exerted by the blood.

The normal blood pressure used to be 120/80 mm Hg. But as per the revised standards, the healthy blood pressure is defined as a blood pressure that is less than 120/80 mm Hg as blood pressures as low as 115/75 mm Hg can also cause heart, vascular and neurological problems.

There are two ways of measuring blood pressure, which are:

1) The Auscultatory method

2) The Oscillometric method

Auscultatory Method

In this method, a stethoscope and a sphygmomanometer (BP Apparatus) are used. Following steps are the direction to note the BP:

� Place cuff tightly around the middle of the upper arm (above the elbow at roughly the same vertical height as the heart).

� Place the bell of your stethoscope over the pulse point just below the cuff.

� Pump up the cuff until it is tight enough to stop the blood flow.

� Slowly deflate the cuff using the knob over the rubber bulb and listen via the stethoscope.

� Note the pressure reading when you hear the first faint sounds, which means some blood has started to pass through the vessels under the cuff. This is the maximum (upper) or systolic pressure.

� Note the last sound before all sounds stop. Now blood is flowing freely. This is the minimum (lower) or diastolic pressure.

� Record the blood pressure reading as systolic over diastolic

Oscillometric Method.

This method is similar to the auscultatory method functionally. As this measurement does not require many skills, therefore, it can be even used by the patients themselves for regular monitoring of their BP.

� The cuff in this type of manometer comes with an electronic pressure sensor fitted in the cuff which detects the blood flow.

� The mercury manometer is fitted on the wrist and elevated to the height of the heart though the upper arm is always preferred.

� The cuff is inflated and released by an electrically operated pump that gives out a numerical reading of the blood pressure.

� This a battery operated instrument

� Digital oscillometric BP monitors are also confronted with "special conditions" for which they are not designed to be used like arteriosclerosis, arrhythmia, preeclampsia and many others

� Consent your health care provider before purchasing this instrument

So, next time you go to your doctor�s clinic make sure you get your BP noted as an early diagnosis will prevent you from many complications your raised blood pressure can cause.