Validation of an oscillometric blood pressure measuring device: a substudy of the HOT Study. Hypertension Optimal...

The accuracy of a semi-automated oscillometric blood pressure measuring device (Visomat OZ D2 International) was studied by simultaneous comparison with a standard sphygmomanometer in 407 normotensive subjects and hypertensive patients. Four pairs of measurements, at least 1 min apart, were obtained from all patients. The oscillometric device tended to give lower measurements than the standard device; the mean difference was -0.9 mmHg for diastolic blood pressure and -6.4 mmHg for systolic blood pressure. The size of this difference was not dependent on the mean blood pressure. Intra-individual standard deviations were similar with the two techniques. The oscillometric device tended to produce higher readings on the first measurement than on the subsequent three, whereas the reverse was true of the standard sphygmomanometer. It is concluded that the oscillometric device used in the HOT Study provides reliable measurements of blood pressure. The slight difference in mean readings between the two methods is unlikely to be of importance for the comparison of differences in treatment blood pressure values in the HOT Study.