Microvascular blood flow during vascular occlusion tests assessed by diffuse correlation spectroscopy

Area of Science:

• Physiology
• Vascular Biology
• Hemodynamics

Background:

• Vascular function assessment often uses the vascular occlusion test (VOT).
• Responses across different vascular beds after cuff release are not well understood.
• Potential differences in vascular compliance may affect blood flow dynamics.

Purpose of the Study:

• To compare blood flow responses in the brachial artery, cutaneous microcirculation, and skeletal muscle microcirculation during a VOT.
• To investigate potential mechanistic differences in blood flow distribution following transient ischemia.
• To determine if cutaneous circulation accurately represents overall vascular function.

Main Methods:

• Utilized laser Doppler-derived blood flux (LDFcut) for cutaneous circulation.
• Employed diffuse correlation spectroscopy (DCS) for skeletal muscle microvascular blood flux (BFI).
• Measured brachial artery blood flow (BABF) using Doppler ultrasound.
• Compared time-to-peak blood flow responses after cuff release across vascular beds.

Main Results:

• Skeletal muscle BFI showed a significantly longer time to peak (32.3 ± 6.0 s) compared to BABF (7.3 ± 2.5 s) and LDFcut (10.0 ± 6.4 s).
• Time to peak for BABF, LDFcut, and total hemoglobin (total-[Hb]) were not significantly different.
• These findings indicate distinct blood flow regulation between cutaneous and muscular compartments post-ischemia.

Conclusions:

• Skeletal muscle microvascular blood flow recovery is notably slower than in the cutaneous circulation after transient ischemia.
• Mechanistic differences exist in the control and distribution of blood flow between skin and muscle.
• The cutaneous circulation may not be a universally representative measure of overall vascular function.