Efficacy of Parallel Capillary Arrays in Modelling Oxygen Transport in Discrete Microvascular Networks

Parallel Capillary Array (PCA) models have frequently been used to model oxygen transport in the microvasculature. Our objective was to compare digitally Reconstructed Microvascular Networks (RMN) to PCA models under several simulated physiological conditions. Two discrete networks were reconstructed from intra‐vital video microscopy of rat skeletal muscle (volumes of interest 84x168x342 μm and 70x157x268 μm). Blood flow in individual capillaries was analyzed and measurements for velocity, hematocrit and oxygen saturation were recorded in the majority of vessels. Flow was modeled for each RMN and adjusted to match velocity profiles measured experimentally. Geometric analysis of the RMNs was used to create equivalent PCAs that were matched in volumetric dimension, vascular density and mean capillary diameter. A computational model of O 2 transport was used to compare RMN to PCA models under 3 conditions (Baseline, 2X Increased Flow & O 2 Consumption, and 37% Functional Capillary Density Loss). O 2 supply rate was equalized between the RMN and paired PCA in each of the three conditions. Mean percent tissue pO 2 difference between the RMN and PCA was −11.9 ± 0.9% at baseline, −13.5 ± 0.4% with increased flow and consumption and −50.8 ± 34.9% with perfusion loss. This suggests that under some conditions PCA models do not suitably represent microvascular geometry when applied to oxygen transport modeling. Funded by CIHR