Hemodynamic effects of attachment modes and device design of a thoracic artificial lung.

ABSTRACT

A thoracic artificial lung (TAL) was designed to treat respiratory insufficiency, acting as a temporary assist device in acute cases or as a bridge to transplant in chronic cases. We developed a computational model of the pulmonary circulatory system with the TAL inserted. The model was employed to investigate the effects of parameter values and flow distributions on power generated by the right ventricle, pulsatility in the pulmonary system, inlet flow to the left atrium, and input impedance. The ratio of right ventricle (RV) power to cardiac output ranges between 0.05 and 0.10 W/(L/min) from implantation configurations of low impedance to those of high impedance, with a control value of 0.04 W/(L/min). Addition of an inlet compliance to the TAL reduces right heart power (RHP) and impedance. A compliant TAL housing reduces flow pulsatility in the fiber bundle, thus affecting oxygen transfer rates. An elevated bundle resistance reduces flow pulsatility in the bundle, but at the expense of increased right heart power. The hybrid implantation mode, with inflow to the TAL from the proximal pulmonary artery (PA), outflow branches to the distal PA and the left atrium (LA), a band around the PA between the two anastomoses, and a band around the outlet graft to the LA, is the best compromise between hemodynamic performance and preservation of some portion of the nonpulmonary functions of the natural lungs.