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.
1. An apparatus for analyzing a gas concentration in a breath of a patient, the apparatus comprising:
a sample compartment that captures the breath;
a breath analyzer that determines a breath rate of the patient;
a gas analyzer that determines a gas concentration of the breath in the sample compartment, wherein the gas concentration comprises one selected from the group consisting of a carbon monoxide concentration and a carbon dioxide concentration;
a processor comprising an algorithm that determines a degree of non-homogeneity of the breath sample in the sample compartment based on the breath rate of the patient, wherein the algorithm further determines a corrected gas concentration based on the breath rate of the patient, the degree of non-homogeneity, and the determined gas concentration; and
an output device that communicates the corrected gas concentration.
2. The apparatus of claim 1 , further comprising a flow control pump which draws breath through the sample compartment.
3. The apparatus of claim 1 , wherein the breath analyzer determines at least one of a start or an end of a sub-portion of the patient's breath.
4. The apparatus of claim 3 , further comprising a valve on at least one of an inlet and an outlet of the sample compartment, and wherein the sub-portion of the patient's breath is isolated by controlling the valve based on the start or the end of the sub-portion of the patient's breath.
5. A method of analyzing a gas concentration in a breath of a patient comprising:
capturing the breath in a sample compartment;
determining a breath rate of the patient using a breath analyzer;
determining a gas concentration of the breath in the sample compartment using a gas analyzer, wherein the gas concentration comprises one selected from the group consisting of a carbon monoxide concentration and a carbon dioxide concentration; and executing instructions from a processor for
determining a degree of non-homogeneity of the breath in the sample compartment based on the breath rate of the patient;
determining a corrected gas concentration based on the breath rate of the patient, the degree of non-homogeneity, and the determined gas concentration; and
communicating the corrected gas concentration to an output device.
6. The method of claim 5 , further comprising drawing breath through the sample compartment with a flow control pump.
7. The method of claim 5 , further comprising determining at least one of a start or an end of a sub-portion of the patient's breath using the breath analyzer.
8. The method of claim 7 , further comprising isolating a sub-portion of the breath in the sample compartment based on at least one of the start or the end of the sub-portion of the patient's breath.