Ensuring the accuracy of digital sphygmomanometers for home use

To describe the techniques for assessing the accuracy of digital sphygmomanometers.

The necessary equipment and the recommended procedures for determining the accuracy of digital units by comparison with a mercury sphygmomanometer were reviewed.

Evaluation of the accuracy of digital sphygmomanometers is a simple two-phase process: (1) comparison of the pressure sensors against a mercury column and (2) assessment of the ability to detect Korotkoff sounds. The only equipment needed is a mercury column, a Y tubing, a "dummy" arm, two male-female adapters, and a stethoscope. The two short ends of the Y tubing are used to connect the mercury sphygmomanometer and the digital unit, and the long end of the Y tubing is attached to the cuff of the digital unit. The inflation mechanism of the digital unit (manual or automatic) influences the approach used for comparing the two units. For both manually and automatically inflatable digital units, the digital display should be within +/- 4 mm Hg of the mercury level; likewise, a properly functioning digital unit should detect Korotkoff sounds (both systolic and diastolic readings) within +/- 4 mm Hg of the auscultated blood pressure measurements. If the digital sphygmomanometer is judged to be accurate, 6-month reevaluations are suggested.

With use of minimal equipment, digital sphygmomanometers (except the new finger blood pressure monitors) can easily be assessed for accuracy by comparing the pressure sensors against a mercury unit and testing the sensitivity for detecting Korotkoff sounds. Self-monitoring of the blood pressure is helpful in assessing blood pressure changes over time and in evaluating antihypertensive therapy.