Alternatives to the mercury sphygmomanometer.

The mercury sphygmomanometer was introduced over 100 years ago. Mercury, however, is a potent human neurotoxin. An international effort has developed to eliminate health-care sources of mercury--the thermometer and sphygmomanometer--and replace them with less toxic alternatives. There is concern regarding the accuracy of these alternative devices. We conducted a literature review of articles published between 1995 and 2009 evaluating the accuracy of mercury, aneroid, and oscillometric blood pressure devices. Mercury sphygmomanometers fared the best although they do not always perform as expected, failing calibration tests between 1 and 28 per cent of the time. Up to 61 per cent of aneroid sphygmomanometers failed. Recently calibrated aneroid devices performed well. Oscillometric devices were less studied and their performance was variable. All three devices showed variable performance. They should be validated before purchase and calibrated on a regular basis.