Kinetic differences between macro- and microvascular measures of reactive hyperemia
Miles F Bartlett1, Andrew Oneglia1, Manall Jaffery1
1Applied Physiology and Advanced Imaging Laboratory, The University of Texas at Arlington, Arlington, Texas.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 17, 2020
Summary
Investigating reactive hyperemia in human skeletal muscle, this study found that both macrovascular and microvascular blood flow peak during reperfusion are influenced by the duration of ischemia and perfusion pressure. These factors, rather than inherent vessel differences, dictate reperfusion kinetics.
Area of Science:
- Physiology
- Biomedical Engineering
- Hemodynamics
Background:
- Reperfusion kinetics differ between macro- and microvasculature post-ischemia.
- Near-infrared diffuse correlation spectroscopy (NIR-DCS) offers noninvasive microvascular perfusion monitoring.
- Understanding these differences is crucial for diagnosing and treating circulatory disorders.
Purpose of the Study:
- To compare macro- and microvascular reperfusion kinetics during reactive hyperemia in human skeletal muscle.
- To investigate the effects of ischemic duration and perfusion pressure on reperfusion dynamics.
- To utilize Doppler ultrasound and NIR-DCS for simultaneous macro- and microvascular assessment.
Main Methods:
- 16 healthy young adults underwent limb ischemia (3 vs. 6 minutes) at heart level.
- Forearm perfusion pressure was manipulated by arm position (above/below heart level).
- Doppler ultrasound measured macrovascular flow; NIR-DCS measured microvascular blood flow index (BFI).
Main Results:
- Peak macrovascular and microvascular reperfusion increased with longer ischemia (6 min > 3 min).
- Peak macro- and microvascular reperfusion, and microvascular reperfusion rate (BFI slope), were significantly affected by perfusion pressure (below heart > neutral > above heart).
- The rate of microvascular reperfusion (BFI slope) was not affected by ischemic duration.
Conclusions:
- Kinetic differences in macro- versus microvascular reperfusion are primarily driven by fluid mechanical energy (pressure, gravity, kinetic energy).
- These factors, not inherent vascular properties, largely determine reperfusion dynamics following ischemia.
- The study highlights the utility of combining Doppler ultrasound and NIR-DCS for comprehensive hemodynamic assessment.
