Hydrodynamic characteristics of artificial lungs.

An artificial lung is used during cardiopulmonary bypass to oxygenate blood and to control blood temperature. The pressure drop-flow rate characteristics of the membrane compartment in three hollow fiber membrane oxygenators were determined in vitro to characterize design features. Results are presented in a unique dimensionless relationship between Euler number, N Eu (ratio of pressure drop to kinetic energy), and Reynolds number, N Re (ratio of inertial to viscous forces), and are a function of the device porosity, e, and a characteristic device length, ξ, defined as the ratio of the mean blood path and manifold length: N Eu .ξ/e 2 = α + β/N Re .e.(1-e) This dimensionless approach allows us (1) to compare oxygenators independently, and (2) to relate water tests to blood.