Figure 1. Definitions of baseline and hyperemic brachial artery blood flow velocity and diameter parameters for the assessment of flow-mediated dilation.

Blood flow velocity (A) and diameter curves (B) obtained by beat-to-beat analysis of Duplex video images. Raw data curves (red) were smoothed (blue) to reduce noise, particularly in the peak change estimates. Baseline blood flow velocity (v_base) and diameter (D_base) were determined over the 120 seconds prior to cuff-inflation. The peak change in blood flow velocity (Δv_peak) was determined as the maximum velocity reached within 180 seconds after cuff-release while the mean change in blood flow velocity (Δv_mean) was determined as the average velocity over the 180 seconds after cuff-release, both minus the baseline blood flow velocity v_base (A). The peak change in diameter (ΔD_peak) was determined as the maximum diameter reached within 180 seconds after cuff-release minus the baseline diameter D_base (B). Indicated also are the full area under the curve of the hyperemic velocity curve above baseline level (Δv_AUC) and the area integrated till peak-time of velocity curve (Δv_{AUC_peak}). ▲indicates the timing of rapid cuff inflation and release.