Integrated Evaluation of Macro- and Microvascular Function in Human Limbs Using Simultaneous Application of FMD and NIRS Techniques

Abstract

PURPOSE: Endothelial dysfunction is an early indicator of cardiovascular disease. Regular exercise improves vascular function, highlighting the need for accurate assessment of exercise-induced vascular adaptations. This study introduces a simultaneous evaluation method that combines flow-mediated dilation (FMD) using Doppler ultrasound and vascular occlusion testing (VOT) using near-infrared spectroscopy (NIRS) to assess vascular responses at both the macrovascular and microvascular levels. METHODS: We present a unified assessment protocol that integrates Doppler ultrasound-based FMD and NIRS-VOT. This study systematically outlines the experimental procedures, including participant preparation, equipment configuration, measurement protocols, data analysis methods, and clinical interpretation strategies. To ensure accurate and reproducible vascular-function assessment, standardized guidelines are provided for subject preparation (e.g., fasting and medication restriction), ultrasound imaging, NIRS probe placement, and occlusion parameters such as pressure and duration. RESULTS: This combined approach provides a non-invasive means to assess vascular function at both the macrovascular and microvascular levels while also capturing their functional interactions. CONCLUSIONS: The proposed method enables an integrated assessment of vascular adaptations across multiple levels, offering insights into the physiological mechanisms underlying exercise-induced vascular improvements. It may serve as a valuable tool in exercise research and clinical evaluation of vascular health.