TESTING THE PARA-CORPOREAL ARTIFICIAL LUNG USING COMPUTER MODELS

Abstract

Using mathematical models developed recently for the ovine cardiovascular system, for the Para-corporeal Artificial Lung (PAL) device, and for its attachment to the pulmonary circulation, we test the putative effectiveness of different graft and PAL device designs in terms of quantitative changes in heart work and right ventricular driving point impedance relative to control (unassisted) levels. We examine the sensitivity of the graft attachment and PAL device parameters on the driving point impedance of the right heart. Of special interest is the effect of the compliance of the inflow chamber of the PAL device on the driving point impedance. We show in a further model study that time varying pneumatic modulation of the external pressure of the inflow chamber, if in proper phasic relationship to right ventricular pumping, enhances pulmonary flow and reduces the work of the right ventricle. In the figure, RT1, CT1, LT1, RT2, CT2, LT2: resistance (R), compliance (C), and enertance (L) of the inlet and outlet graft. CIC, RIC, RTIC: compliance, axial and transmural resistance of inflow chamber. RAL, CAL: resistance and compliance of the artificial lung chamber. Pth: Thoracic Pressure. Pex: time-varying external pressure of the inflow chamber.Figure