Sphygmomanometer

Sphygmomanometer

A traditional sphygmomanometer

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A sphygmomanometer is a medical device used to measure blood pressure. It consists of an inflatable cuff to restrict blood flow, and a mercury or mechanical manometer to measure the pressure. It is always used in conjunction with a means to determine at what pressure blood flow is just starting, and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope.

History

The sphygmomanometer was invented by Samuel Siegfried Karl Ritter von Basch in 1881. The device was further developed by Scipione Riva-Rocci in 1896, and it was popularized by Harvey Cushing, who introduced it to the United States in 1901.

Types of Sphygmomanometers

There are several types of sphygmomanometers:

• Mercury sphygmomanometers: Considered the gold standard for blood pressure measurement, they measure pressure using a column of mercury. They require careful handling due to the toxicity of mercury.

• Aneroid sphygmomanometers: These use a mechanical dial to measure pressure. They are portable and do not contain mercury, but require regular calibration.

• Digital sphygmomanometers: These are electronic devices that automatically measure blood pressure and display the results on a digital screen. They are easy to use and are commonly used in home settings.

Procedure for Use

To measure blood pressure using a sphygmomanometer, follow these steps:

1. Preparation: Ensure the patient is seated comfortably with their arm supported at heart level. The patient should be relaxed and not have consumed caffeine or smoked for at least 30 minutes prior.

2. Cuff Placement: Wrap the cuff snugly around the upper arm, with the lower edge about an inch above the elbow.

3. Inflation: Inflate the cuff by squeezing the bulb until the pressure is about 20-30 mmHg above the expected systolic pressure.

4. Deflation and Measurement: Slowly deflate the cuff while listening with a stethoscope placed over the brachial artery. Note the pressure at which the first Korotkoff sound is heard (systolic pressure) and the pressure at which the sound disappears (diastolic pressure).

5. Recording: Record the systolic and diastolic pressures, and repeat the measurement if necessary to ensure accuracy.

Maintenance and Calibration

Regular maintenance and calibration of sphygmomanometers are essential to ensure accurate readings. Mercury sphygmomanometers should be checked for leaks and mercury levels, while aneroid devices require periodic calibration against a standard.

Also see

• Blood pressure measurement
• Hypertension
• Stethoscope
• Cardiology

References

• "The History of Blood Pressure Measurement". Journal of Medical History.
• "Guidelines for Blood Pressure Measurement". American Heart Association.