| A thoracic artificial lung (TAL) is attached to the pulmonary circulation with blood flow through it driven by the right ventricle. An anastomosis to the proximal main pulmonary artery (PA) leads to the TAL inlet. Split outflow from the TAL leads to the distal main PA and left atrium (LA). Selective banding reduces the attachment configuration to one that is in parallel with the natural lungs (NL), in series with the NL or in an intermediary hybrid configuration.; The TAL and the geometry of the PA anastomoses were characterized in vitro. The hemodynamic and oxygenation consequences of TAL attachment configuration were investigated in an in vivo porcine model. A computational model was developed to study the oxygenation consequences of TAL attachment configuration under additional, anticipated conditions.; The mechanical energy losses across the PA anastomoses can exceed those across the TAL. The losses across the TAL inlet and outlet exceed that across the gas-exchange fiber bundle.; The in vivo experiments consisted of attaching the TAL, collecting baseline data and adjusting the bands to create, in sequence: parallel, hybrid, series, repeat hybrid, repeat parallel and repeat baseline configurations. Most hemodynamic parameters were not significantly different in the repeat configurations than in the corresponding initial configurations. Mean LA pressure increased progressively throughout the experiment, however, which may indicate damage caused by graft attachment to the LA. Parallel attachment lowered pulmonary system impedance and raised cardiac output. Parallel attachment was hemodynamically advantageous, but NL blood flow is important for embolic clearance and metabolic function. Hybrid and series attachment raised pulmonary system impedance and lowered cardiac output. Hybrid attachment was nearly as severe as series, but TAL redesign may lessen its severity. The right ventricle may be ischemic in hybrid or series, due to high workload and low oxygen delivery.; The oxygenation model predicts elevated oxygenation in parallel and reduced oxygenation in hybrid and series. In a disease model with only hemodynamic NL abnormality (elevated pulmonary vascular resistance), oxygenation is perfusion-limited. In a disease model including impaired oxygen diffusion in the NL, the TAL must receive a high fraction of cardiac output. |
