The Reliability of Auscultatory Measurement of Arterial Blood Pressure: A Comparison of the Standard and a New Methodology

In 48 individuals with a wide range of arm circumferences blood pressure measured indirectly with two different cuffs was compared to direct intraarterial measurements. The two cuffs were a standard size cuff (12 X 35 cm) and a newly developed cuff, containing three rubber bags of different sizes, which automatically selects the appropriately sized bag in relation to arm circumference (Tricuff, Pressure Group AB, Sweden). The Tricuff correctly placed 42 of the 43 patients in the "normotensive" range, ie, diastolic blood pressure less than 90 mm Hg, whereas the standard cuff put only 33 of 44 patients in this range (P less than .005). The discrepancy was not only due to the expected better performance in patients with obese arms, but also in the subgroup of patients with arms in the range 22 to 31 cm, in which group both cuffs would measure blood pressure with a 12 cm wide rubber bag. The number of correctly identified "normotensive" patients was noticeably higher with the Tricuff than with the standard cuff (30/31 v 25/32, P = .053). The better specificity of the new cuff thus offers an improvement over the standard cuff. There are several potential clinical advantages of this, mainly that the risk of erroneously labelling normotensive individuals as hypertensive is reduced.