Comparison of ankle-brachial index measured by an automated oscillometric apparatus with that by standard Doppler technique in vascular patients.

Abstract

To evaluate the determination of ankle-brachial indices (ABIs) using a simple automated ankle pressure measurement device in comparison with the Doppler technique. ABI was measured in 61 patients (122 legs) admitted to the department of vascular surgery, Rigshospitalet. ABI was calculated twice using both the methods on both legs. We tested the automated oscillometric blood pressure device, CASMED 740, for measuring ankle and arm blood pressure and compared it with the current gold standard, the hand-held Doppler technique, by the Bland-Altman analysis. Using the Doppler-derived ABI as the gold standard, the sensitivity and specificity of the oscillometric method for determining an ABI<or=0.9 is 71% and 92%, respectively. The overall accuracy for correctly identifying an ABI of 0.9 with the oscillometric method was 82%. Ankle pressures measured by CASMED 740 were systematically higher in patients with reduced ankle pressures, but accurate in patients with ankle pressures above 90 mm Hg. Automated oscillometric assessment of ankle blood pressure and ABI may falsely categorise PAD patients as having a normal ankle pressure and ABI.