The relation between capillary transit times and hemoglobin saturation heterogeneity. Part 1: Theoretical models

Adrien Lücker, Timothy W. Secomb, Bruno Weber, Patrick Jenny

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Capillary dysfunction impairs oxygen supply to parenchymal cells and often occurs in Alzheimer's disease, diabetes and aging. Disturbed capillary flow patterns have been shown to limit the efficacy of oxygen extraction and can be quantified using capillary transit time heterogeneity (CTH). However, the transit time of red blood cells (RBCs) through the microvasculature is not a direct measure of their capacity for oxygen delivery. Here we examine the relation between CTH and capillary outflow saturation heterogeneity (COSH), which is the heterogeneity of blood oxygen content at the venous end of capillaries. Models for the evolution of hemoglobin saturation heterogeneity (HSH) in capillary networks were developed and validated using a computational model with moving RBCs. Two representative situations were selected: a Krogh cylinder geometry with heterogeneous hemoglobin saturation (HS) at the inflow, and a parallel array of four capillaries. The heterogeneity of HS after converging capillary bifurcations was found to exponentially decrease with a time scale of 0.15-0.21 s due to diffusive interaction between RBCs. Similarly, the HS difference between parallel capillaries also drops exponentially with a time scale of 0.12-0.19 s. These decay times are substantially smaller than measured RBC transit times and only weakly depend on the distance between microvessels. This work shows that diffusive interaction strongly reduces COSH on a small spatial scale. Therefore, we conclude that CTH influences COSH yet does not determine it. The second part of this study will focus on simulations in microvascular networks from the rodent cerebral cortex. Actual estimates of COSH and CTH will then be given.

Original languageEnglish (US)
Article number420
JournalFrontiers in Physiology
Volume9
Issue numberAPR
DOIs
StatePublished - Apr 26 2018

Keywords

  • Blood flow
  • Capillary transit time heterogeneity
  • Computational modeling
  • Hematocrit
  • Hemoglobin saturation
  • Microcirculation
  • Oxygen transport
  • Red blood cells

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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