Accuracy of the Omron RX-M, an automated blood pressure measuring device, measuring blood pressure at the wrist, according to a modified British Hypertension Society protocol

OBJECTIVE: To determine the accuracy of the Omron RX-M, a device measuring blood pressure oscillometrically at the wrist. METHODS: In 89 subjects (mean age 55+/-14 years) blood pressure measurements at the wrist with the Omron RX-M were compared to sequential blood pressure measurements with a mercury sphygmomanometer at the (same) upper-arm and to simultaneous measurements with the Omron HEM-705 CP at the opposite arm.Measurements with analyzed according to the British Hypertension Society (BHS) - protocol 1993, to the protocol of the Association for the Advancement of Medical Instrumentation (AAMI) and (retrospectively) to the new 'International Protocol'. RESULTS: Mean differences (+/-SD) between the measurements with the mercury sphygmomanometer and the Omron RX-M were -7.5+/-8.4 mmHg for diastolic blood pressure (DBP) and -2.5+/-12.2 mmHg for systolic blood pressure (SBP), thus not fulfilling the AAMI-criteria (< or =5+/-8). According to the BHS-criteria a grade D was achieved for both DBP and SBP. Compared to the Omron HEM 705 CP results were -6.3+/-7.1 for DBP (grade D) and -4.1+/-12.7 for SBP (grade D). The Omron RX-M also failed to pass the new 'International Protocol' in phase 1. CONCLUSION: Although easy to use, based on this study the Omron RX-M can not be recommended to determine blood pressure accurately.