| Theoretical and experimental techniques were used to develop high efficiency artificial lungs that consist of blood flowing perpendicular to fiber banks. These investigations include a theoretical numerical model, experimental development of both static and dynamic intravascular lung assist devices (ILAD's), and development of a prototype pumping artificial lung (PAL). The model, based on a numerical solution of O{dollar}sb2{dollar} transfer from a single microporous fiber, approximates the overall O{dollar}sb2{dollar} transfer from a bank of such fibers to blood flowing perpendicular to the fiber axes. Unlike other models, it does not require experimental evaluation of any parameters to accurately predict the O{dollar}sb2{dollar} transfer over a wide range of fiber bank arrangements and membrane oxygenator inlet conditions. The model is shown to accurately predict gas transfer rates for a variety of commercial oxygenators under wide ranges of operating conditions.; The ILAD development included investigations of the effect on gas exchange and hemodynamics of fiber motion. In vitro testing of the devices examined the effects of the (i) mode of fiber motion, rotation or oscillation, (ii) frequency of fiber motion, and (iii) amplitude of fiber motion in the case of oscillation. The advantages of fiber rotation were applied to the development of a PAL, an extracorporeal device that pumps blood with centrifugal motion of the gas exchanging fibers.; All ILAD and PAL designs resulted in efficient gas exchange, i.e., high transfer rate per unit surface area, and the ILAD's with very little pressure drop. To achieve sufficient transfer, i.e., clinically significant transfer rates, the surface areas of the ILAD's must be increased or the efficiency increased further. The PAL's have proven to be effective pumps and efficient oxygenators. |
