PMS Instruments: Methods of measuring blood pressure

Frequently Asked Questions

Methods of measuring blood pressure.

Blood pressure may be measured directly or indirectly. The direct, or invasive intra-arterial method is used for physiological research and is carried out by introducing a miniature manometer or catheter into the lumen of an artery. The catheter is connected to a blood pressure transducer which converts mechanical energy into electrical energy. In turn, this is used to produce a visual display of the blood pressures.

Because this method can effectively record every blood pressure generated with every beat of the heart, direct monitoring is believed to be the most accurate method of blood pressure detection, and is considered the gold standard by which to measure the accuracy of other blood pressure measurement devices and methods.

The first indirect device for measuring arterial blood pressure was designed in 1854. In 1896, Riva-Rocci added the pneumatic cuff to the upper arm for obliteration of the radial pulse. The inflated cuff was used to occlude the brachial artery, causing the radial pulse to disappear. The blood pressure in the artery was determined when the pressure in the cuff was slowly released and radial pulse reappeared.

Only nine years after the Riva-Rocci theory was introduced, a Russian physician by the name of Korotkoff described the tapping and murmuring sound heard while using a stethoscope over the brachial artery while it was occluded by a pneumatic cuff. This discovery gave birth to modern sphymomanometry, while using a mercury column and the auscultatory method of identifying blood pressure. Today, both oscillometric and auscultatory sphymomanometry are used.

Oscillometric measurements are accomplished with the use of a blood pressure cuff and tactile sensors which measure pressure waves in the cuff as blood surges through the constricted artery.

Most modern digital blood pressure monitors use the Oscillometric technique for Hospital accuracy.

Auscultatory measurements are made with the help of a stethoscope which allows for the auditory sensing of the blood rushing through the brachial artery. As K-sounds are identified by the observer taking a blood pressure measurement, the level of mercury on a mercury column or the meter point on an aneroid manometer is recorded.