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 (less than or equal to 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. (C) 2004 Lippincott Williams Wilkins.