Hematocrit distribution and tissue oxygenation in large microcirculatory networks

Area of Science:

• Physiology
• Biomedical Engineering
• Computational Fluid Dynamics

Background:

• Brain oxygen tension relies on red blood cell (RBC) microcirculatory supply.
• The impact of non-Newtonian blood flow on tissue oxygenation requires further characterization.

Purpose of the Study:

• To assess biphasic blood flow models for predicting tissue oxygen tension based on microcirculatory hemodynamics.
• To introduce and validate a novel biphasic blood flow model.

Main Methods:

• Compared existing plasma-skimming laws with measured RBC distributions in rat and hamster microcirculatory networks.
• Developed and applied a novel biphasic blood flow model.
• Predicted tissue oxygenation in the mesentery, cremaster muscle, and human secondary cortex.

Main Results:

• Identified deficiencies in prior models, including inconsistent plasma-skimming and inadequate oxygen perfusion (33% RBC-free microvessels).
• The novel method produced physiologically sound RBC distributions and tissue oxygen tensions within one standard deviation of experimental data.

Conclusions:

• Introduced a simple, novel biphasic blood flow model with superior or equal predictive power compared to existing models.
• The model effectively handles microcirculatory complexities like trifurcations, anastomoses, and loops.
• This new plasma-skimming law simplifies computations and converges faster for large microcirculatory networks.