Inaccuracy of electronic sphygmomanometers.

1. Eight electronic sphygmomanometers were purchased locally and evaluated for clinical accuracy during blood pressure recording on volunteer patients. 2. Direct comparisons of systolic and diastolic pressure were made in seven devices using a Y-tube connection to a mercury sphygmomanometer, simultaneous measurements being made by a trained observer on 16-18 subjects. 3. Indirect comparisons were made for all eight devices by comparing the average values obtained from all measurements made on each subject by the device with the average value from mercury sphygmomanometric readings made over the same time period. 4. Results were analysed by measuring the mean and standard deviation of the differences between device readings and mercury readings. Published criteria were used to grade the devices. 5. The most accurate machine was the Omron HEM-719K, which used the cuff as a sound sensor and had an internal microphone. The least accurate was the Omron HEM-812F, which used a finger-cuff method. The other devices (all oscillometric) ranged from fair to poor in performance accuracy.