The invention relates to an arrangement (10, 100) for removing carbon dioxide from an extracorporeal flow of blood and/or for oxygenating the extracorporeal flow of blood. The arrangement (10, 100) comprises an oxygenator (12), a first gas storage tank (24) in which a first gas is contained and at least a second gas storage tank (24) in which a second gas is contained. Further the device (10, 100) has a gas mixing unit for mixing a purge gas from the first and the second gas and an electronic control unit (30) for controlling the gas mixing unit (50). The control unit (30) comprises an input unit (40) by means of which the content of the first gas in the purge gas is adjustable by an operator, wherein the control unit (30) controls the gas mixing unit (50) such that the purge gas has the adjusted content of the first gas.
