The subject matter of the application is a device for adjustment and/or regulation of the CO2, carbon dioxide content of the inhaled air. Device based on the invention where a CO2 vessel 30 is connected to the CO2 input aperture 22, a measuring tool 15 determining the CO2 content of the exhaled air is connected to the exhaled air pipe 11, the output aperture of the measuring tool 15 is connected to the input aperture of a control unit 50, and the output aperture of the control unit 50 is connected to the valve 28 adjusting the blending rate of blending vessel 20 and so adjusting the CO2 content of the inhaled air.
