The accuracy of the Marshall 85 oscillometric sphygmomanometer in the ambulatory care setting

The purpose of this study was to evaluate a partially automated sphygmomanometer for accuracy in the ambulatory care setting. Patients seen in 80 consecutive office visits served as subjects. Blood pressures were measured simultaneously under standard conditions. The oscillometric test instrument and a standard mercury manometer were connected with a Y tube. Paired t-tests were used to determine statistical differences between values obtained from the two instruments. Analyses were done by age, sex, and blood pressure range. While mean differences in blood pressure values were statistically significant in almost every instance, the quantitative differences were 5 mmHg or less with one exception. The differences, although statistically significant, were not great enough to be clinically important. We conclude that the Marshall 85 oscillometric sphygmomanometer is sufficiently accurate for limited use in the ambulatory care setting.