[Diffusion of oxygen and carbon dioxide in a stationary membrane oxygenator].

Univariate diffusion of oxygen and carbon dioxide through a selective membrane of a stationary membranous oxygenator (SMO) and moving blood film is considered. Through the use of a precise exponential approximation of the oxyhemoglobin dissociation curve [S (p)=1--ae-bp] a partial oxygen pressure distribution [p (x)] along the SMO membrane and a transcedental equation for estimating the value for partial pressure (pa) of the arterialized blood and the SMO efficiency with reference to oxygen have been obtained. A somewhat less exact logarithmic approximation of the summary blood oxygen concentration [C1=a1+b1ln(p--po)] enables it to arrive at an analytical expression for calculating the SMO efficiency with reference to oxygen in a positively definite form. On the other hand, by using logarithmic approximation of the summary carbon dioxide concentration proceeding from the partial CO2 pressure in the blood a partial CO2 pressure distribution along the membrane, as well as an analytical expression for estimating the SMO efficiency with reference to carbon dioxide could be obtained.