Membrane blood oxygenators: Oxygen mass transfer in a gas/membrane/liquid system

Despite the widespread use and the decades of continuous developments of the Membrane Blood Oxygenators, several aspects related to the membrane/blood interactions, circulating blood flow conditions and equipment design still need to be improved. Fundamental studies of the blood flow and blood/membrane interface are required to fully understand the effect of the membranes surface and of the conditions of circulation on the gas transfer. The oxygen mass transfer of integral asymmetric hemocompatible polyurethane-based membranes was investigated in a MBO surrogate system that allow the direct assessment to the oxygen fluxes. This system consists of a slit for water circulation as a surrogate blood flow channel and a constant pressure oxygen chamber separated by the membranes in study. A model of the oxygen mass transport in this system was previously verified. The oxygen fluxes were predicted for different conditions of operation. The effect of the circulation conditions and oxygen feed pressure on the required membrane area to assure oxygen physiological needs was investigated. The contribution of the liquid boundary layer resistance is evidenced by the increase of the oxygen fluxes with the increase of the liquid flow rates. The present benchmark device can accommodate membrane/boundary layer disruptors to promote flow fields, enhancing the oxygen mass transfer. Membrane/boundary layer disruptors composites are prepared by deposition of electrospunned fibers over the membranes surface. Their effect in the oxygen mass transfer and blood integrity is under investigation.