A system of controlling the perfusion parameters and the efficacy of extracorporeal gas exchange is described. The system has been developed and employed for the control and regulation of gas exchange in the MOST-122 oxygenators manufactured in the USSR and based on selective composition membranes. The system allows an expeditious assessment of gas exchange disorders which may occur during AC and extracorporeal oxygenation as well as their high-accuracy correction, reaching optimal modes of ventilation.