Sphygmomanometer

A sphygmomanometer is a medical device used to measure blood pressure. It consists of an inflatable cuff to restrict blood flow, and a manometer to measure the pressure. The device is used in conjunction with a method to determine the pressure at which blood flow begins and at which it is unimpeded.

History

The sphygmomanometer was invented in 1881 by Samuel Siegfried Karl Ritter von Basch. The device was further developed by Scipione Riva-Rocci in 1896, who introduced the use of an inflatable cuff. The modern sphygmomanometer was developed by Harvey Cushing, who introduced the use of the device in the United States.

File:Sphygmomanometer WWI Memorial de Verdun.JPG

Early sphygmomanometer used during World War I

Types

There are several types of sphygmomanometers:

Mercury Sphygmomanometer

The mercury sphygmomanometer is considered the gold standard for measuring blood pressure. It uses a column of mercury to measure pressure and is known for its accuracy.

Clinical mercury manometer

Aneroid Sphygmomanometer

The aneroid sphygmomanometer uses a mechanical gauge with a dial to measure pressure. It is more portable than the mercury type but requires regular calibration.

Digital Sphygmomanometer

Digital sphygmomanometers are electronic devices that automatically measure blood pressure and display the results on a digital screen. They are easy to use and do not require a stethoscope.

Modern digital sphygmomanometer

Components

A typical sphygmomanometer consists of the following components:

• Cuff: A fabric band that wraps around the arm and inflates to restrict blood flow.
• Bulb: A rubber bulb used to inflate the cuff.
• Valve: A valve to release air from the cuff.
• Manometer: A device to measure the pressure in the cuff.

File:Sphygmomanometer&Cuff.JPG

Sphygmomanometer with cuff

Measurement Technique

The measurement of blood pressure using a sphygmomanometer involves the following steps:

1. The cuff is placed around the upper arm and inflated to a pressure higher than the expected systolic pressure. 2. The pressure in the cuff is slowly released while listening with a stethoscope over the brachial artery. 3. The first sound heard (Korotkoff sound) indicates the systolic pressure. 4. The point at which the sound disappears indicates the diastolic pressure.

Diagram of Korotkoff sounds

Clinical Use

Sphygmomanometers are used in various clinical settings to monitor blood pressure. They are essential tools in diagnosing and managing hypertension and other cardiovascular conditions.

Checking blood pressure with a sphygmomanometer

Related Pages

• Blood pressure
• Hypertension
• Cardiovascular system