Sphygmomanometer Health Article

Definition

A sphygmomanometer is a device for measuring blood pressure.

Purpose

The sphygmomanometer is designed to monitor blood pressure by measuring the force of the blood in the heart where the pressure is greatest. This occurs during the contraction of the ventricles, when blood is pumped from the heart to the rest of the body (systolic pressure). The minimal force is also measured. This occurs during the period when the heart is relaxed between beats and pressure is lowest (diastolic pressure).

A sphygmomanometer is used to establish a baseline at a healthcare encounter and on admission to a hospital. Checking blood pressure is also performed to monitor the effectiveness of medication and other methods to control hypertension, and as a diagnostic aid to detect various diseases and abnormalities.

Description

A sphygmomanometer consists of a hand bulb pump, a unit that displays the blood pressure reading, and an inflatable cuff that is usually wrapped around a person's upper arm. Care should be taken to ensure that the cuff size is appropriate for the person whose blood pressure is being taken. This improves the accuracy of the reading. Children and adults with smaller or larger than average-sized arms require special sized cuffs appropriate for their needs. A stethoscope is also used in conjunction with the sphygmomanometer to hear the blood pressure sounds. Some devices have the stethoscope already built in.

A sphygmomanometer can be used or encountered in a variety of settings:

• home
• hospital
• primary care clinic or professional office
• ambulance
• dental office
• pharmacy and other retail establishment

There are three types of equipment in common use for monitoring blood pressure.

• A mercury-based unit has a manually inflatable cuff attached by tubing to the unit that is calibrated in millimeters of mercury. During blood pressure measurement, the unit must be kept upright on a flat surface and the gauge read at eye level. Breakage of the unit may cause dangerous mercury contamination and would require specialist removal for disposal. Due to the hazards of mercury, the use of mercury-based sphygmomanometers has declined sharply since 2000.
• An aneroid unit is mercury free and consists of a cuff that can be applied with one hand for self-testing; a stethoscope that is built in or attached; and a valve that inflates and deflates automatically with the data displayed on an easy-to-read gauge that will function in any position. The unit is sensitive and if dropped may require recalibration.
• An automatic unit is also mercury-free and is typically battery-operated. It has a cuff that can be applied with one hand for self-testing, and a valve that automatically inflates and deflates. Units with manual inflation are also available. The reading is displayed digitally and a stethoscope is not required. This is useful for persons who are hearing-impaired, for emergency situations when staff is limited, and for automatic input into instruments for storage or graphical display. A wrist monitor is also available for home testing. Some more expensive models also remember and print out recordings. The automatic units tend to be more portable than bulkier mercury devices.