Collection and analysis of a volume of exhaled gas with compensation for the frequency of a breathing parameter

Apparatuses are described to accurately determine a gas concentration of a sample of a patient's breath. The apparatuses may include a sample compartment, a breath speed analyzer, a gas analyzer, and a processor. The sample compartment includes an inlet that receives the breath. The breath speed analyzer determines the speed of a portion of the breath. The gas analyzer determines a gas concentration. The processor includes an algorithm that determines a degree of non-homogeneity of the sample based on the speed, and a corrected gas concentration based on the degree of non-homogeneity. In some variations, the gas correction is determined independently of patient cooperation. Apparatuses may be tuned based on the intended population's expected breathing pattern ranges such that the sample compartment is filled with a homogenous end-tidal gas sample regardless of an individual's breathing pattern. These apparatuses are useful, for example, for end-tidal CO analysis. Methods are also described. 11404844_1 (GHMatters) P97599.AU.2 Figure SA 510 502 514 522 524 Pt a c Ill 526 V1 520 518 V2 512 528 Figure 5B 502 514 530 522 524 532 501 b b b Pt a V C-a vi c a V2 C cV3 a 510 526 520 518 536 528 534