Using a Sphygmomanometer
The measured blood pressure is the radial pressure exerted by the blood column againt the arterial wall.

In a normal patient, this pressure varies between 120 mm of Hg and 80 mm of Hg.



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When a cuff is inflated to 160 mm of Hg, the arteries collapse and circulation is temporarily suspended. As blood flow does not occur, no sound is audible.



The korotkoff sounds that are heard while measuring BP are due to disturbance in the streamlined flow of blood. When auscultating an artery without applying pressure no sounds should be heard in a normal person. Generally they are heard when blood flow occurs in spurts. This occurs when the cuff pressure is lesser than the systolic pressure but more than the diastolic pressure.