Predicted oxygenation efficacy of a thoracic artificial lung.

A thoracic artificial lung (TAL) provides respiratory support for lung disease. How well a TAL improves blood oxygenation for a specific pathology depends on how the TAL is attached to the pulmonary circulation: in series with the natural lungs (NLs), in parallel, or in a hybrid series/parallel combination. A computational model, including hemodynamic and O(2) and CO(2) exchange components, predicts TAL effects on blood flow rates and gas transport in pulmonary disease states modeled by elevated pulmonary vascular resistance (PVR) or reduced oxygen diffusivity in the NLs. In most cases, parallel and series TAL attachment provide comparable, maximal oxygenation. Series, with passage of total cardiac output (CO) through the NLs, is preferred for its filtration of emboli. Hybrid TAL attachment is more complicated, requiring a third graft, yet oxygenates less well than parallel and series. With extreme elevations of PVR, as in primary pulmonary hypertension, parallel TAL attachment provides an oxygenating shunt around the high resistance of the NLs, thus unloading the right ventricle, normalizing CO, and maximizing oxygenation.