Validation of the OMRON M7 (HEM-780-E) blood pressure measuring device in a population requiring large cuff use according to the International Protocol of the European Society of Hypertension

Background A high percentage of hypertensive patients present an arm circumference of over 32 cm; the use of a large cuff is therefore recommended. Validation studies are usually performed in the general population using a standard-size cuff. The aim of this study was to assess the accuracy of the Omron M7 device in a population with an arm circumference ranging from 32 to 42 cm. Design A validation study was performed according to the International Protocol of the European Society of Hypertension. This protocol is divided into two phases: the first phase is performed on 15 selected participants (45 pairs of blood-pressure measurements); if the device passes this phase, 18 supplementary participants are included (54 pairs of blood-pressure measurements), making a total number of 33 participants (99 pairs of blood-pressure measurements), on whom the analysis is performed. Methods For each participant, four blood-pressure measurements were performed simultaneously by two trained observers, using mercury sphygmomanometers fitted with a Y tube; the measurements alternated with three by the test device. The difference between the blood-pressure value given by the device and that obtained by the two observers (mean of the two observations) was calculated for each measure. The 99 pairs of blood-pressure differences were classified into three categories (<= 5, <= 10 and <= 15 mmHg). The number of differences in each category was compared with the number required by the European Society of Hypertension protocol. Results The Omron M7 device passed the first and the second phases of the validation process. The average differences between the two observers were 1.5 +/- 3.2 and -0.5 +/- 2.2 mmHg for systolic blood pressure and diastolic blood pressure, and those between the device and the mercury sphygmomanometer were -1.6 +/- 6.7 for systolic blood pressure and -0.12 +/- 4.0 mmHg for diastolic blood pressure Readings that differ by less than 5, 10 and 15 mmHg for systolic blood-pressure and diastolic blood-pressure values fulfill the recommendation criteria of the European Society of Hypertension protocol. Conclusions The Omron M7 (HEM-780-E) device fulfilled the validation criteria of the international protocol in a population with an arm circumference ranging from 32 to 42 cm.