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

Abstract

Objectives: To evaluate the determination of ankle-brachial indices (ABIs) using a simple automated ankle pressure measurement device in comparison with the Doppler technique.

Design: 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.

Materials and methods: 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.

Results: 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.

Conclusion: Automated oscillometric assessment of ankle blood pressure and ABI may falsely categorise PAD patients as having a normal ankle pressure and ABI.