Diastolic Ankle-Brachial Indices as a Complementary Measure to Screen for Peripheral Arterial Disease in Diabetic Patients

Abstract

Introduction Ankle-brachial systolic pressure ratio or Index (ABI or ABI-S) has influenced cardiovascular screening for decades. Total or partial rigidity (i.e. calcification) of tibial arteries has hampered Doppler ABI-S measurements in patients with diabetes. Diastolic pressures are measurable with the oscillometric technique. The authors of a previous study demonstrated that ABI-D (ankle-brachial index based on diastolic pressure ratio) was less sensitive than ABI-S, but partial or total incompressibility of tibial arteries was suspected if ABI-D < ABI-S. This study examined whether ABI-D added information to screen for peripheral arterial disease (PAD) in patients with diabetes. Methods An “eye-to-foot” screening/educational program was performed at the city of Arapiraca, state of Alagoas, northeast of Brazil. A vascular surgeon, an expert on the diabetic foot, selected subjects with decreased pulse and/or older age. Bilateral arm and ankle pressures were performed in 71 diabetic patients: 47 (66%) women and 24 (34%) men, 68 ± 10 years (range, 46–86). ABI-S and ABI-D were calculated on the basis of bilateral brachial and ankle oscillometric pressures. Screening for PAD was compared on the basis of the prevalence of ABI < 0.90. Results ABI-S, ABI-D, or either ABI < 0.90 were detected in 36 (51%), 48 (68%), and 55 (77%) diabetics, respectively. ABI-S and ABI-D, only ABI-S, or only ABI-D were <0.90 in 53% (n = 29), 13% (n = 7), and 35% (n = 19) of the 55 diabetics with ABI < 0.90. The increase in frequency of ABI < 0.90 was significant if ABI-D complemented ABI-S ( p < 0.001 by chi-square). ABI-D and ABI-S were 0.83 ± 0.06 (0.68–0.895) versus 1.01 ± 0.10 (0.92–1.30) in the only ABI-D < 0.90 group. Conclusions Diastolic ankle pressures were estimated successfully by use of the oscillometric technique. Diastolic ABI correlated with expert physician assessment and contributed to quantitative screening for PAD in diabetic patients with apparently falsely elevated systolic ABI caused by partial incompressibility of tibial arteries.