Blood Pressure Measurement

How Does a Sphygmomanometer Measure Blood Pressure?

Overview of the Sphygmomanometer

• A sphygmomanometer, commonly known as a blood pressure cuff, is designed to measure blood pressure in millimeters of mercury (mmHg).

• The device consists of a rubber cuff that wraps around the arm and is connected to a pressure gauge.

• A stethoscope is placed against the brachial artery to detect pulse sounds during measurement.

Measurement Process

• The cuff is inflated to create pressure that temporarily blocks blood flow through the artery, resulting in no audible pulse sounds.

• As the cuff deflates slowly, systolic pressure is determined when the first pulse sounds are heard.

• Diastolic pressure is assessed when pulse sounds can no longer be detected, typically at maximum deflation.

• Blood pressure readings are expressed as a ratio of systolic over diastolic pressures; for example, 126/90 mmHg.