Artificial-lung design: sheet-membrane units

Two-Dimensional Finite Element Model for Oxygen Transfer in Cross-Flow Hollow Fiber Membrane Artificial Lungs

A predictive, two-dimensional model with good absolute accuracy for flow and mass transfer in cross-flow hollow fiber membrane artificial lungs is developed. The proposed model is able to predict the gas transfer to water flowing outside and perpendicular to hollow fibers in the artificial lung. The model uses a finite element technique to solve the Navier-Stokes equations and the convection-diffusion equation on the computational domain of a unit fiber cell. Subsequent stream-wise and cross-wise unit fiber cells are then coupled/assembled to the relationship between the oxygen transfer rate and flow rate of a cross-flow hollow fiber membrane artificial lung. The model is compared to experimental water data obtained by perfusing three commercial artificial lungs with water.

Mathematical and experimental methods for design and evaluation of membrane oxygenators

Three categories of membrane oxygenators are considered: passive flow, secondary flow induced by the mainstream, secondary flow induced by an external application of energy. The current status of mathematical methods for analysis of fluid mechanics, O2 and CO2 exchange for these categories are briefly reviewed. Emphasis is given to approximate methods for calculation of gas exchange. Practical methods for experimental design optimization studies are outlined; these methods are extended to evaluation of O2 and CO2 exchange in clinical operation. A new method for estimation of internal ventilation and perfusion maldistribution and diffusion resistance is described. A brief assessment of blood damage in clinical application of the oxygenator is presented from the point of view of deterioration of gas exchange performance.