Home blood pressure measurement: validation of the Braun BP 2550 (UG) monitor according to the ESH International Protocol.

BACKGROUND

The Sixth Report of the Joint National Committee states that the 'measurement of blood pressure outside the clinician's office may provide valuable information for the initial evaluation of patients with hypertension and for monitoring the response to treatment'. Prior to their marketing, however, blood pressure measuring devices should be independently validated for safety and accuracy using standard guidelines.

OBJECTIVE

The main objective of the present study was the clinical evaluation of the Braun Precision Sensor 2550 upgrade (Braun BP 2550 (UG)) according to the International Protocol of the European Society of Hypertension (ESH).

METHODS

Measurements of systolic and diastolic blood pressure in 33 subjects were obtained using the mercury sphygmomanometer (Baumanometer) and the device. The sizes of the cuffs used for different arm circumferences were 12 x 23 cm, 15 x 33 cm and 18 x 36 cm for the thin adult, adult and overweight adult, respectively. The adult size was mostly used. If the cuff of the sphygmomanometer did not fall between the two range lines, a larger or smaller cuff was required. The reproducibility of self-blood pressure measurement was compared in 33 subjects (99 measurements). Nine sequential same-arm measurements comparing the test device and the standard mercury sphygmomanometer were carried out according to the International Protocol of the ESH in three steps (phases 1, 2.1 and 2.2).

RESULTS

The device passed phases 1 and 2.1 as 75 systolic and 78 diastolic readings fell within 5 mmHg, exceeding the total of 65 required for approval. It also passed phase 2.2 as 30 subjects for systolic and 29 for diastolic had at least two out of three comparisons within 5 mmHg, exceeding the 22 subjects required. The difference-against-mean plots showed that the device-sphygmomanometer disagreement was -1.58+/-4.84 for systolic pressure (the Braun being lower) and +2.23+/-3.84 for diastolic pressure (the Braun being higher), respectively.

CONCLUSIONS

The equipment passed both phases of the International Protocol (subject measurements and subject accuracy). The difference of 0-5 mmHg between the sphygmomanometer and the device represents 'measurements considered to be very accurate and with no error of clinical relevance'. It can therefore be used at home as an adjunct to physicians' effort to control blood pressure in their hypertensive patients.