[Measuring blood pressure at the wrist: critical analysis of a validation study]

The new device "Blood Pressure Watch" (BPW) by NAIS-Matsushita, which measures blood pressure oscillometrically at the hand wrist, is preferred by many hypertensive patients as a device for self-measurements because of its smallness and simple applicability.

To evaluate the accuracy of blood pressure measurements with this device we determined the blood pressure four times consecutively in the aortic arch using a Statham P23 and the BPW simultaneously at the left hand wrist in 27 patients (58.6 +/- 10.3 [range: 36 to 76] years; 21 male) after a coronary angiography.

With a correlation coefficient of 0.85 for systolic and 0.84 for diastolic pressure mean blood pressure was determined higher (systolic: +1.4 +/- 10.1 mm Hg, diastolic: +4.4 +/- 7.6 mm Hg) by the BPW compared to the aortic arch pressure. While there was no correlation between systolic differences and patients' age, it could be demonstrated that with increasing age the BPW exhibited higher diastolic blood pressure values than those measured in the aortic arch. Multiple regression analysis revealed that this was due to inability of the BPW to detect low diastolic blood pressures (r = 0.89, p < 0.001).

1. For the majority of hypertensive patients the hand wrist device is suitable for self-measurement of blood pressure. It is advisable to perform an auscultatory comparative test at least once before buying such a device. 2. The oscillometric method for measuring blood pressure does not seem to be the proper method for epidemiologic studies and investigation of population groups in which lower diastolic pressure ranges are to assumed.