Brachial cuff lacks accuracy in measuring intra-arterial BP

The accuracy of brachial cuff towards intra-arterial (IA) blood pressure (BP) is lacking in several patients, which could potentially result in higher risk of BP mismanagement and inaccurate determination of central BP, a study has found.

The authors measured cuff brachial systolic BP (bSBP) and central SBP in 303 individuals using a Mobil-o-Graph simultaneously to IA bSBP and aortic SBP. Based on the difference between IA and cuff bSBP, three phenotypes were named: underestimation (cuff bSBP < IA bSBP by >10 mm Hg); no mismatch (cuff bSBP within 10 mm Hg of IA bSBP); overestimation (cuff bSBP > IA bSBP by >10 mm Hg) phenotypes.

Subsequently, the authors determined the risk of overtreatment and undertreatment as well as the accuracy (ARTERY society criteria: mean difference ≤5±8 mm Hg). They also assessed variable associated with the bSBP difference using a multiple linear regression model.

The underestimation (n=142), no mismatch (n=136), and overestimation (n=25) phenotypes had comparable characteristics and cuff bSBP (124±17, 122±14, 127±19 mm Hg, respectively; p=0.19), but different aortic SBP (133±21, 120±16, 112±18 mm Hg, respectively; p<0.001).

More than half (59 percent) in the underestimation phenotype were at risk of undertreatment (14 percent in no mismatch), while half (50 percent) in the overestimation phenotype were at risk of overtreatment (17 percent in no mismatch).

Cuff bSBP had an accurate estimate of aortic SBP only in the no mismatch group (mean difference, 1.6±8.2 mm Hg), whereas central BP never met the accuracy criteria. Of note, lesser underestimation of bSBP difference was associated with male sex, higher height, and active smoking.

“This illustrates the need to improve the accuracy of cuff-based BP monitors,” the authors said.