Accuracy of prehospital sphygmomanometers.

The first requisite for valid blood pressure determination is a correctly calibrated manometer. A total of 125 aneroid sphygmomanometers in prehospital use were calibrated against a mercury manometer standard. A total of 43 (34.4%) aneroid instruments deviated by more than +/- 4 mm Hg tolerance (average of four readings). A deviation of greater than +/- 8 mm Hg was shown by 10.4% (13) of the maeters. These aneroid gauges are easily calibrated by prehospital personnel using a mercury standard and Y-tube connection. Departments with routine maintenance policies had fewer inaccurate instruments. Emergency medical services advisors should ensure periodic maintenance and calibration of sphygmomanometers used in emergency care situations.