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Health and Medicine - How Is Blood Pressure Measured?

How is blood pressure measured?

Blood pressure is measured by a device called a sphygmomanometer. This device was invented in 1876 by German physician Samuel Siefried von Basch (1837-1905). A sphygmomanometer consists of an arm cuff, a rubber bulb, an inflatable bladder, and a scale that indicates the pressure of blood.

To measure blood pressure, the cuff is wrapped around the upper arm, above the artery at the inside elbow. The rubber bulb is then squeezed and the bladder inflated, thus tightening the cuff to the point that blood flow through the artery is blocked. Then the air is gradually released from the bladder, which causes the cuff to gradually loosen.

As blood returns to the artery, the person taking the blood pressure reading listens through a stethoscope placed over the artery. First there is a thumping sound, which indicates that blood is exerting the systolic pressure (when the heart muscle is...

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