Troncoconical cuffs must be used to measure BP in individuals with severe obesity

It appears that only troncoconical cuffs can provide accurate blood pressure (BP) measurement in very obese people since cylindrical cuffs overestimate BP mainly in those with high systolic (S)BP, suggests a new study.

The upper arm shape in all obese participants was troncoconical (mean slant angle, 84.1±1.4°). Compared with controls, difference in SBP and diastolic BP between the troncoconical and the cylindrical cuffs in this cohort were −5.3±4.0 (p<0.001) and −3.0±4.3 mm Hg (p=0.01).

Obese participants in the top BP quintile had between-cuff SBP difference of −9.1±5.1 mm Hg. Arm slant angle independently predicted between-cuff SBP discrepancy (p=0.003).

There was a clear difference in measurement with the pressure sensor between the pressure in the cuff and the pressure transmitted to the arm (mean difference, –10.2±5.2 mm Hg) when the cylindrical cuff was used. This increased with increasing level of the pressure pumped in the cuff.

In this study, the authors investigated the effect of the shape of the cuff on BP measurement in participants with severe obesity. They compared cylindrical and troncoconical cuffs of appropriate size in 33 participants with upper arm mid-circumference at least 42 cm and 33 controls. Additionally, a paper-thin pressure sensor was used to measure the pressure transmitted to the arm under the cuffs at five cuff pressure levels in obese participants.

“Rectangular (cylindrical) cuffs and bladders are currently used for BP measurement at the upper arm. However, large arms have a troncoconical shape, which make cylindrical cuffs potentially unsuitable,” the authors said.