A testing device for evaluation of gas transfer through synthetic membranes

Abstract

An experimental set‐up was designed to allow the determination of the gas transfer rates between human blood and pure O₂ through a synthetic membrane. This device permitted the obtention of known steady states. It consisted of a thermostated closed blood loop containing a capillary oxygenating cell with a functional area of 400 cm². The thickness of the blood film in the capillaries was about 150 μ. The type of membrane under study consisted of a supporting cellulosic paper, impregnated with a silicone elastomer. The manufacturing process allowed to get reproduceable hydrophobic microporous membranes without selective permeability in gas to gas phase. The continuous evaluation of the “expired” CO₂ flow rate was achieved with an accurate titration method. O₂ and CO₂ transfer rates were also determined on the blood phase. In parallel mounting of two oxygenators permitted an intercomparison of membranes. The results gained from this study permitted to consider one of these membranes (6.5 g silicone/m²) as suitable for incorporation into a blood oxygenator. Moreover, agitation of the blood capillaries at a suitable frequency resulted in a substantial increase of O₂ and CO₂ transfer rates.