Use of anthropometric indices to identify appropriate cuff shapes for blood pressure measurement: normative data for adults

Published evidence has shown that tronco-conical cuffs improve BP measurement accuracy in obese subjects. However, the exact shape of these cuffs according to arm size has not been established. The aim of the present study was to investigate the anthropometric characteristics of the upper arm in a large population in order to identify the appropriate shape of the cuff according to arm size.Anthropometric characteristics were assessed in 729 adults with middle arm circumference ranging from 16 to 55 cm. Upper arm length and proximal, middle, and distal circumferences were measured to calculate the slant angle of the upper-arm truncated cone. Subjects were divided into 6 classes of upper arm middle circumference, and the upper arm slant angle was calculated within each class.In all subjects the upper arm showed a tronco-conical shape with a slant angle ranging from 80.4 to 89.2. The conical shape of the arm progressively increased with increasing arm circumference (r = 0.61,p < 0.0001). Independent predictors of the conical shape were arm circumference (p < 0.0001) and length (negative relationship, p < 0.0001). Women had a slightly more pronounced conical shape of the arm than men. In a two-way ANOVA, a significant effect of both arm size (p < 0.001) and sex (p = 0.001) was found on the conical shape of the arm. However, the decrease in the slant angle across the arm size classes showed a similar trend in men and women, and in the two-way ANOVA there was no interactive effect between arm size and gender (p = 0.11). On the basis of the slant angle calculated in each arm-size class, we identified appropriate dimensions for bladders that would fit the arm within a given circumference range. The upper arm slant angle and the proximal-distal circumference difference for the 4 cuff sizes (small adult, adult, large adult, and extra-large adult) recommended by the American Heart Association were also provided.To properly fit the upper arm, cuffs should have a tronco-conical shape especially in obese individuals. This study provides reference data for appropriate proximal and distal circumferences of bladders according to arm size.