Evaluation of Plasma Resistant Hollow Fiber Membranes For Artificial Lungs

Abstract

Hollow fiber membranes (HFMs) used in artificial lungs (oxygenators) undergo plasma leakage (or wetting) in which blood plasma slowly fills the pores of the fiber wall, plasma leaks into gas pathways, and overall gas exchange decreases. To overcome this problem plasma resistant fibers are being developed that are skinned asymmetric or composite symmetric versions of microporous oxygenator fibers. This report evaluates several candidate plasma resistant HFMs in terms of their gas permeance and plasma resistance as measured in a surfactant wet out test. Five candidate fibers were compared with each other and with a control fiber. CO2 and O2 gas permeance (in ml/s/cm2/cm Hg) in the plasma resistant fibers ranged from 3.15E-04 to 1.71E-03 and 3.40E-04 to 1.08E-03, respectively, compared with 1.62E-02 and 1.77E-02 for the control fiber. Maximum dye bleed through for the plasma resistant fibers in the forced wet out test were significantly less than for the control fiber. CO2 gas permeance of a plasma resistant fiber imposes the greatest constraint upon artificial lung design for sufficient gas exchange. However, our results suggest sufficient plasma resistance can be achieved using special skinned and composite HFMs while maintaining an acceptable CO2 gas permeance for a broad range of artificial lung applications.

Recovery of [CO2]T from Aqueous Bicarbonate using a Gas Permeable Membrane

“…In the context of typical micorporous membrane systems, the membrane permeability in gas-liquid systems has been shown to be on the order of two to five times slower than gas-gas systems ( Table 2). This difference has been attributed to liquid infiltration into the membrane pores along with slower gas diffusion in a liquid medium [12][13][14]24]. However, since CO 2 is in the ionic form as carbonate and bicarbonate in this gas-liquid membrane system, the degree of flux across the membrane will also be dependent on the rate of CO 2 disproportionation in the system and the relatively much more rapid ion mobility to the membrane surface.…”

“…Most of these applications are near atmospheric pressure and include water purification, blood oxygenation and artificial lung devices [11][12][13][14]. However some are operated at higher pressures such as beverage carbonation [15,16].…”

Blood Biocompatibility Assessment of an Intravenous Gas Exchange Device

“…Future studies will involve application of a micron thick siloxane coating on the fibers to prevent plasma penetration into hollow fiber pores without adversely impacting mass exchange rates (13). A bioactive heparin coating might also be deposited on top of the siloxane layer.…”

Extracorporeal life support: Updates and controversies

“…[15][16][17][18][19][20][21] Newer hollow-fiber gas-exchange devices allow for lower priming volumes and have decreased plasma leakage, which enhances clinical application of these low-resistance lungs. [22][23][24] Perhaps the largest change in ECLS technology is related to the introduction of bi-caval dual-lumen cannulas. Veno-venous ECLS is now most commonly provided in children and adults using bicaval dual-lumen cannulas.…”