Background: Reactive hyperemia (RH) is a temporary increase in blood flow following ischemia and serves as a marker of vascular health by reflecting reductions in arterial stiffness. Pulse transit time (PTT) and finger-to-finger pulse arrival time difference (f–f ∆T) are non-invasive techniques used to assess vascular stiffness. This study compares the effectiveness of PTT and f–f ∆T in detecting vascular stiffness changes induced by RH.
Methods: Ten healthy male participants (mean age: 23.1 ± 5.0 years) were enrolled. PTT and f–f ∆T were measured at baseline and at 1-minute intervals for 5 minutes following RH induction. RH was induced by occluding the left arm for 5 minutes.
Results: PTT increased significantly by 6% and 4% at 1 and 2 minutes post-occlusion release, respectively, compared to baseline (260.9 ± 19.1 ms). In contrast, f–f ∆T showed larger relative increases of 362%, 200%, 133%, and 88% at 1, 2, 3, and 4 minutes, respectively, compared to baseline (5.1 ± 7.4 ms). While PTT exhibited only modest and short-lived changes, f–f ∆T changes
were more substantial and persisted longer.
Conclusion: The f–f ∆T method demonstrated greater sensitivity in detecting RH-induced changes in vascular stiffness compared to PTT, with effects lasting up to 4 minutes. In contrast, PTT detected only transient changes, primarily within the first 2 minutes. These findings suggest that f–f ∆T may offer a more sensitive approach for assessing vascular compliance during RH.