Accuracy of a wrist blood pressure monitor

The traditional way of measuring blood pressure uses a cuff that goes on the upper arm. Recently, wrist monitors have been introduced that are much smaller and easier to use than arm monitors. They also have the advantage that the same cuff size can be used in fat and thin people, because the diameter of the wrist is affected little by obesity, in comparison with the upper arm.

A study conducted in Switzerland compared the blood pressure measured by a wrist monitor (the Omron R3) with the traditional mercury sphygmomanometer measuring blood pressure from the upper arm, and a catheter placed directly in the artery, which is the ‘gold standard’ of blood pressure measurement. It was done in 100 patients who were undergoing catheterization of their hearts, which entailed measurement of blood pressure from inside the major arteries. It was found that the wrist monitor gave readings that were a little closer to the pressure measured directly from the artery than the readings given by the mercury sphygmomanometer.

Doctor’s Comments

This study shows that the Omron wrist monitor can give accurate measurements of blood pressure, even when it gives readings that differ from the conventional mercury sphygmomanometer. The main source of error with the wrist monitors is that the monitor has to be at the level of the heart when the reading is taken (which was not a problem with this study, because the patients were all lying flat when the readings were taken).

Where It Was Published

S Watson and colleagues. Accuracy of a new wrist cuff oscillometric blood pressure device. Comparison with intra-arterial and mercury manometer. American Journal of Hypertension 1998; p.1469

By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

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