Unilateral post-occlusive reactive hyperemia significantly reduced bilateral coherence for blood flow (CSSI 0.89 to 0.07, p=0.002), whereas sympathetic-driven responses remained synchronized.
Observational (n=12)
Does unilateral post-occlusive reactive hyperemia alter bilateral synchrony of neurovascular responses in healthy young adults?
Unilateral post-occlusive reactive hyperemia induces a marked loss of bilateral coherence in microvascular signals while sympathetic-driven responses remain synchronized, revealing systemic autonomic adjustments beyond local hemodynamics.
Absolute Event Rate: 0.07% vs 0.89%
p-value: p=0.002
Post-occlusive reactive hyperemia (PORH) is widely used to assess microvascular reactivity, but its systemic impact on contralateral neurovascular function remains unclear. This study quantified bilateral synchrony and asymmetry of cutaneous signals during unilateral PORH in healthy subjects using a novel multidimensional framework of inter-limb coherence. Twelve young adults underwent a standard suprasystolic occlusion (5 min at 200 mmHg) on the upper limb, while photoplethysmography (PPG), skin temperature, and electrodermal activity (EDA) were recorded bilaterally in the fingers. Coherence was characterized by profile similarity (Cross-Signal Similarity Index, CSSI), temporal lag (τ*), magnitude asymmetry (Bilateral Magnitude Difference Index, BDMI), directional concordance (Signal Direction Index, SDI; Directional Concordance Index, DCI), and integrated indices (IBIL, IBIS). At baseline, all signals showed high bilateral synchrony (CSSI ≈ 0.9; τ* < 20 ms). Occlusion markedly reduced CSSI for blood flow (0.89 to 0.07, p = 0.002) and temperature (0.93 to −0.03, p = 0.06), while EDA coherence remained preserved (0.95 to 0.82). Integrated indices decreased significantly (IBIL 0.84 to 0.17, p = 0.005; IBIS 0.84 to 0.18, p = 0.004) and recovered only partially during hyperemia (IBIL 0.20, p = 0.003). Directional concordance was heterogeneous: during hyperemia, 9 of 12 subjects showed concordant EDA changes but only 7 of 12 for perfusion. BDMI was largest for perfusion (≈0.8), moderate for temperature (≈0.5), and minimal for EDA (≈0.3). Unilateral PORH thus induces a marked loss of bilateral coherence in microvascular signals, whereas sympathetic-driven responses remain strongly synchronized. This dissociation reveals that occlusion evokes systemic autonomic adjustments beyond local hemodynamics. The proposed framework captures hidden aspects of neurovascular integration and may provide new markers for autonomic imbalance or perfusion asymmetry.
Silva et al. (Sun,) conducted a observational in Healthy subjects (n=12). Unilateral suprasystolic occlusion vs. Baseline was evaluated on Cross-Signal Similarity Index (CSSI) for blood flow (p=0.002). Unilateral post-occlusive reactive hyperemia significantly reduced bilateral coherence for blood flow (CSSI 0.89 to 0.07, p=0.002), whereas sympathetic-driven responses remained synchronized.