Comparison of Generated Parallel Capillary Arrays to Three-Dimensional Reconstructed Capillary Networks in Modeling Oxygen Transport in Discrete Microvascular Volumes

ObjectiveWe compare RMN to PCA under several simulated physiological conditions to determine how the use of different vascular geometry affects oxygen transport solutions. MethodsThree discrete networks were reconstructed from intravital video microscopy of rat skeletal muscle (84x168x342m, 70x157x268m, and 65x240x571m), and hemodynamic measurements were made in individual capillaries. PCAs were created based on statistical measurements from RMNs. Blood flow and O-2 transport models were applied, and the resulting solutions for RMN and PCA models were compared under four conditions (rest, exercise, ischemia, and hypoxia). ResultsPredicted tissue PO2 was consistently lower in all RMN simulations compared to the paired PCA. PO2 for 3D reconstructions at rest were 28.24.8, 28.1 +/- 3.5, and 33.0 +/- 4.5mmHg for networks I, II, and III compared to the PCA mean values of 31.2 +/- 4.5, 30.6 +/- 3.4, and 33.8 +/- 4.6mmHg. Simulated exercise yielded mean tissue PO2 in the RMN of 10.1 +/- 5.4, 12.6 +/- 5.7, and 19.7 +/- 5.7mmHg compared to 15.3 +/- 7.3, 18.8 +/- 5.3, and 21.7 +/- 6.0 in PCA. ConclusionsThese findings suggest that volume matched PCA yield different results compared to reconstructed microvascular geometries when applied to O-2 transport modeling; the predominant characteristic of this difference being an over estimate of mean tissue PO2. Despite this limitation, PCA models remain important for theoretical studies as they produce PO2 distributions with similar shape and parameter dependence as RMN.