Repeatability of ultrasound parameters in measuring blood flow in the lower limb arteries of asymptomatic diabetic patients with early-stage peripheral artery disease

Abstract

The objectives of the study were to i) To determine the repeatability of ultrasound parameters in measuring lower limb blood flow in diabetic patients with early-stage peripheral artery Disease (PAD) and ii) To determine whether any differences in dependent variables between sessions are significant or meaningful. Ultrasound parameters consisting of peak systolic velocity (PSV), pulsatility index (PI), resistive index (RI) and vessel diameter inner to inner (VDI) were assessed for repeatability in measuring blood flow in the popliteal arteries (PA), anterior tibial arteries (ATA) and posterior tibial arteries (PTA) of 10 asymptomatic Black-African diabetic patients [3 males, 7 females; mean age - 49.5 (13.8) years; mean glycated haemoglobin levels (HbA_1c) - 5.9 (0.7)%; mean Ankle Brachial Index (ABI) 1.1 (0.1)and median Body Mass Index (BMI - 29.5 (24-33.7)] with early stage peripheral artery Disease (PAD). Within and between sessions reliability intraclass correlation coefficients [ICC], percentage coefficient of variation [%CV]), measurement error (standard error of measurement [SEM] and smallest detectable difference [SDD] were calculated for Ultrasound parameters which include peak systolic velocity (PSV), resistive index (RI), pulsatility index (PI), and vessel diameter inner to the inner (VDI) to establish their repeatability in measuring blood flow in the popliteal arteries [PA], anterior tibial arteries [ATA] and posterior tibial arteries [PTA] of diabetic patients with early-stage peripheral artery disease [PAD]. Paired t-tests were performed and effect sizes calculated to establish if the differences between sessions were significant or meaningful. PSV, PI and RI showed very good (ICC ≥0.8; 0.6 – 0.9, 95% CI) to excellent (ICC ≤1.0; 1.0 -1.0, 95% CI) reliability and acceptably low variability (≤5.6%CV) both within and between sessions. The SEM was only high for VDI-PTA (SDD = 13.6%). PSV, PI and RI were repeatable in measuring blood flow in the lower limbs of diabetic patients with early-stage PAD.