Silva Henrique, Rezendes Carlota, Pinto Pedro Contreiras
Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisbon, Portugal.
Department of Pharmacy, Pharmacology and Health Technologies, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisbon, Portugal.
Pflugers Arch. 2025 Sep 2. doi: 10.1007/s00424-025-03110-7.
Post-occlusive reactive hyperemia (PORH) is a physiological response marked by a transient increase in microvascular perfusion following ischemia. While cutaneous perfusion during PORH has been extensively characterized using optical approaches such as Doppler-based techniques, low-cost alternatives like photoplethysmography (PPG), videocapillaroscopy (VC) and near-infrared reflectance imaging (NIRI) may provide complementary insights into both microvascular and venous dynamics. However, their role in quantifying PORH remains underexplored. This study aimed to evaluate the potential of low-magnification VC and NIRI-based imaging for quantifying perfusion changes during a standardized PORH protocol in healthy subjects, using PPG as a reference. Fourteen participants (21.5 ± 4.2 years) underwent suprasystolic occlusion of a randomly selected upper limb, with simultaneous recordings using PPG and VC at the finger and NIRI at the dorsal hand veins. The protocol included a 5-min baseline, 3-min occlusion (200 mmHg), and 5-min recovery. Skin blood flow was derived from the PPG signal, a hemoglobin index (C) was extracted from VC images, and vein width was measured using NIRI. Nonparametric statistics were used for analysis. Arterial occlusion significantly reduced skin blood flow (-95.3%, p < 0.001) and C (-8.3%, p = 0.007), with milder contralateral changes. Vein width increased during occlusion (p = 0.003) and returned to baseline during recovery. VC was less sensitive than PPG but reproduced the expected hemodynamic profile. A positive correlation was found between venous dilation during recovery and the decrement velocity of microvascular perfusion during occlusion. VC and NIRI represent accessible and complementary tools for assessing vascular responses during PORH. Their combined application may enhance non-invasive vascular evaluation in both clinical and research settings.
闭塞后反应性充血（PORH）是一种生理反应，其特征是缺血后微血管灌注短暂增加。虽然使用基于多普勒技术等光学方法对PORH期间的皮肤灌注进行了广泛的表征，但低成本的替代方法，如光电容积脉搏波描记法（PPG）、视频毛细血管显微镜检查（VC）和近红外反射成像（NIRI），可能会为微血管和静脉动力学提供补充见解。然而，它们在量化PORH中的作用仍未得到充分探索。本研究旨在以PPG为参考，评估低倍VC和基于NIRI的成像在量化健康受试者标准化PORH方案期间灌注变化方面的潜力。14名参与者（21.5±4.2岁）对随机选择的上肢进行收缩压以上的闭塞，同时在手指处使用PPG和VC以及在手背静脉处使用NIRI进行记录。该方案包括5分钟的基线期、3分钟的闭塞期（200 mmHg）和5分钟的恢复期。皮肤血流来自PPG信号，从VC图像中提取血红蛋白指数（C），并使用NIRI测量静脉宽度。采用非参数统计进行分析。动脉闭塞显著降低了皮肤血流（-95.3%，p<0.001）和C（-8.3%，p=0.007），对侧变化较轻。静脉宽度在闭塞期间增加（p=0.003），并在恢复期间恢复到基线。VC比PPG敏感性低，但再现了预期的血流动力学特征。发现恢复期间的静脉扩张与闭塞期间微血管灌注的递减速度之间存在正相关。VC和NIRI是评估PORH期间血管反应的可及且互补的工具。它们的联合应用可能会增强临床和研究环境中的无创血管评估。
