Impact of Incremental Perfusion Loss on Oxygen Transport in a Capillary Network Mathematical Model.

Objectives: To quantify how incremental capillary PL, such as that seen in experimental models of sepsis, affects tissue oxygenation using a computation model of oxygen transport. Methods: A computational model was applied to capillary networks with dimensions 84 9 168 9 342 (NI) and 70 9 157 9 268 (NII) lm, reconstructed in vivo from rat skeletal muscle. FCD loss was applied incrementally up to 40% and combined with high tissue oxygen consumption to simulate severe sepsis. Results: A loss of 40% FCD loss decreased median tissue PO2 to 22.9 and 20.1 mmHg in NI and NII compared to 28.1 and 27.5 mmHg under resting conditions. Increasing RBC SR to baseline levels returned tissue PO2 to within 5% of baseline. HC combined with a 40% FCD loss, resulted in tissue anoxia in both network volumes and median tissue PO2 of 11.5 and 8.9 mmHg in NI and NII respectively; median tissue PO2 was recovered to baseline levels by increasing total SR 3-4 fold. Conclusions: These results suggest a substantial increase in total SR is required in order to compensate for impaired oxygen delivery as a result of loss of capillary perfusion and increased oxygen consumption during sepsis.