Patent ID: 7885771

Claim:
An apparatus for the acquisition and interpretation of expirograms comprising: a gas measuring probe configured to determine the gas concentration ƒ mess of a gas in exhaled respiratory air; a reading device that is configured to read, for a plurality of values x 1 , . . . , x N of an exhaled volume of the exhaled respiratory air, the respective determined gas concentrations ƒ mess (x 1 ), . . . , ƒ mess (x N ) from the gas measuring probe; a storage device configured to store the values x 1 , . . . , x N assigned to the gas concentrations ƒ mess (x 1 ), . . . , ƒ mess (x N ); and a function fitting unit that is configured to determine a non-linear fit function ƒ( x ) =g ( x )· h ( x )+Offset Gas for the stored gas concentrations ƒ mess (x 1 ), . . . , ƒ mess (x N ) by determining functions g(x) and h(x) wherein h(x)=a+b·x g(x) is a continuously differentiable, non-linear function, where: g ⁡ ( 0 ) = 0 ⁢ ⁢ and ⁢ ⁢ lim x -> ∞ ⁢ ⁢ g ⁡ ( x ) = const , a, b and const are constants, and Offset Gas is a constant, mean concentration of the gas in room air.