Microvascular Flow Modeling Using In Vivo Hemodynamic Measurements in Reconstructed 3D Capillary Networks

We describe a systematic approach to modeling blood flow using reconstructed capillary networks and in vivo hemodynamic measurements. Our objective was to produce flow solutions that best represent convective O 2 delivery in vivo. Two capillary networks, A & B, with tissue volumes 84×168×342 & 70×157×268 μm were mapped using custom software. Total network red blood cell supply rate (SR) was calculated from in vivo data and used as a target metric for the flow model. To obtain inlet hematocrits, mass balances were applied recursively from downstream vessels. Pressure differences across the networks were incrementally increased to achieve the target SR. Resulting baseline flow solutions were applied to an existing O 2 transport model. To test the impact of flow redistribution on O 2 delivery, asymmetric flow solutions (Asym) were generated by applying a pressure change (±20% of mean pressure gradient) to outlets on the right and left side of the networks. Asym solutions produced a mean absolute difference in SR per capillary of 27.6±33.3% in network A & 33.2±40.1% in network B vs. baseline. The O 2 transport model calculated a mean tissue pO2 of 28.2±4.8 & 28.1±3.5 mmHg for baseline and 27.6±5.2 & 27.7±3.7 mmHg for Asym solutions. This illustrates that moderate changes in flow distribution within a network have little impact on tissue pO 2 provided that total SR remains unchanged. Supported by CIHR MOP 102504 & NIH HL089125