GAS-PERMEABILITY OF HOLLOW-FIBER MEMBRANES IN A GAS-LIQUID SYSTEM

Designing an effective intravenous membrane oxygenator requires select ing hollow fiber membranes (HFMs) which present minimal resistance to gas exchange over extended periods of time. To evaluate HFMs, we devel oped a simple apparatus and methodology for measuring HFM permeability in a gas-liquid environment which has the capability of studying a va riety of fiber types in any liquid of interest, such as blood. Using t his system, we measured the O-2 and CO2 exchange permeabilities of Mit subishi MHF 200L composite HFMs and KPF 280E microporous HFMs in water at 37 degrees C. The membrane permeability measured for the MHF 200L composite fiber was 7.9 X 10(-6) ml/s/cm(2)/cmHg for O-2 and 8.4 X 10( -5) ml/s/cm(2)/cmHg for CO2, and for the KPF 280E microporous fiber, 1 .4 X 10(-5) ml/s/cm(2)/cmHg for O-2 and 3.2 X 10(-4) ml/s/cm(2)/cmHg f or CO2. The permeabilities of the microporous HFMs were over two order s of magnitude less than what would be measured in a gas-gas system du e to liquid infiltration of the pores, emphasizing the importance of m easuring permeability in a gas-liquid system for relevant applications such as intravenous oxygenation. Furthermore, both O-2 and CO2 permea bilities of the microporous fiber were consistent with a liquid infilt ration depth of only 1%. The O-2 permeability of the MHF fiber was fou nd to be less than the overall exchange permeability ultimately requir ed of our intravenous oxygenation device (K approximate to 1 X 10(-5) ml(STP)/s/cm(2)/cmHg). Consequently, the MHF 200L composite fiber appe ars unsuitable for intravenous oxygenation devices such as ours.