Evaluation of normal and large sphygmomanometer cuffs using the Omron 705CP

Sphygmomanometers are usually sold with a single cuff though some are supplied with a short cuff as standard and offer a longer one for larger arms. However, data on the differences in measurements taken with different cuffs applied to different sized arms are conflicting and this study set out to investigate the difference between those taken with 'normal' and 'large' cuffs in arms 28 cm or more in circumference. We avoided observer error by using a semi-automatic digital sphygmomanometer, the Omron 705CP. The 22 subjects employed were selected from one general practice as having a range of previous office blood pressures and a variety of arm sizes above 28 cm in circumference. Omron 'normal' and 'large' cuffs were used alternately, taking five blood pressures with each to a total of 30 readings per patient, resulting in 660 readings, 330 with each cuff. There were mean systolic/diastolic differences of 2.7/3.8 (s.d.s 4.7/2.8) for all subjects. These were greater in the normotensive. When divided into two groups with systolic blood pressures below and equal to or above 140 mm Hg, differences were -1.9/3.0 to 7.1/4.7. From the results of the study, we recommend that large cuffs should be used for all patients with an arm circumference of 28 cm or above but the Omron large cuff still requires formal validation.