Accuracy of the OMRON M4 automatic blood pressure measuring device

Despite widespread use of the automatic blood pressure (BP) measuring devic e OMRON M4, there is little formal validation on its accuracy. A study was conducted to assess the accuracy of the OMRON M4 compared with the true ind irect BP measured by mercury sphygmomanometer (MS). A rapid method for the evaluation of automatic blood pressure measurement devices (READ) was appli ed for this study, The READ is based on numerous BP measurements at rest an d during a standardised postural challenge in a small number of subjects wh o exhibit a wide range of BPs. Blood pressure measurements were done in sup ine position for 10 min followed by head-up tilt for 30 min and again supin e for 10 min. The automatic device (AU) and the MS were connected to one ar m-cuff by means of a T connector. A stethoscope with dual sets of ear-piece s was used for duplicate MS measurements (MS1 and MS2). The MS1, MS2 and AU measurements were taken simultaneously in a blinded manner. Three units of the automatic instrument were evaluated. An average of 111 measurements pe r unit were performed, every BP category being present in greater than or e qual to 15MS measurements, The differences between MS1 and MS2 measurements (Delta BP: MS1-MS2) were utilized to assess the consistency of true indire ct BP and the differences between AU and MS measurements (Delta BP:AU-MSS) were utilized to assess the accuracy of the AU. The following characteristi cs of the OMRON M4 were assessed: (1) grade of accuracy, (2) aberration pat tern, (3) consistency of the aberration-pattern, and (4) correlation betwee n levels of BP and Delta BP: AD-MS, For MS paired readings, 92-100% of syst olic and 99-100% of diastolic readings fell within 5 mm Hg difference range , that is consistent with a British Hypertension Society grade A of both. F or AU compared to MS2, 29-64% of systolic and 73-94% of diastolic readings fell within 5 mm Hg and 49-86% of systolic and 86-99% of diastolic readings fell within 10 mm Hg and the devices qualified C, D and C, respectively. A ll devices exhibited irregular and inconsistent aberration patterns, making the design of correction formulas impractical, In conclusion, the OMRON M4 device did not meet the requirements of the British Hypertension Society a nd, therefore, cannot be recommended for clinical use.