Oral end tidal carbon dioxide method for diagnosing pulmonary arterial hypertension

Patent metadata

Field	Value
Publication number	US-10383546-B2
Application number	US-201815951622-A
Country	US
Kind code	B2
Filing date	Apr 12, 2018
Priority date	Oct 16, 2008
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

This disclosure concerns improved capabilities for evaluating whether additional medical tests need to be conducted for a diagnosis of a pulmonary arterial hypertension (PAH) condition in a patient. The method includes determining that the patient is at rest and measuring a partial pressure of carbon dioxide in a composite gas, comprising: transferring an expiration from the patient's mouth to a carbon dioxide analyzer; measuring end tidal carbon dioxide (EtCO2) from each of a plurality of oral expirations from the patient; and calculating a composite EtCO2 value. The method further includes comparing the composite EtCO2 value to a range of stored carbon dioxide partial pressure values; generating a signal indicating whether additional medical tests need to be conducted in response to the comparing; and providing the generated signal to an indicator, the indicator adapted to respond to the generated signal to provide an output in a human cognizable format.

First claim

What is claimed is:

1. A method for determining whether additional medical tests need to be conducted for a diagnosis of a pulmonary arterial hypertension (PAH) condition in a patient, comprising:
determining that a patient is at rest;
measuring the partial pressure of carbon dioxide in a composite gas of the patient at rest, the measuring comprising:
transferring an expiration from the patient's mouth to the carbon dioxide analyzer;
measuring end tidal carbon dioxide (EtCO 2 ) from each of a plurality of oral expirations from the patient at rest; and
calculating a composite EtCO 2 value in response to the plurality of oral expirations from the patient at rest;

comparing the composite EtCO 2 value to a range of stored carbon dioxide partial pressure values;
generating a signal indicating whether additional medical tests for diagnosing PAH need to be conducted based on the comparing; and
providing the generated signal to an indicator, the indicator adapted to respond to the generated signal to provide an output in a human cognizable format.

2. The method of claim 1 , further comprising generating the signal in response to the comparing by determining that additional medical tests are needed in response to the composite EtCO 2 value being lower than a first predetermined threshold value.

3. The method of claim 2 , wherein the first predetermined threshold value comprises 36 mm Hg.

4. The method of claim 2 , further comprising generating the signal in response to the comparing by determining that additional medical tests are not needed in response to the composite EtCO 2 value being greater than a second predetermined threshold value.

5. The method of claim 4 , wherein the second predetermined threshold value comprises 38 mm Hg.

6. The method of claim 1 , wherein a lower range of the composite EtCO 2 value is indicative of pulmonary arterial hypertension and a higher range of the composite EtCO 2 value is indicative of pulmonary venous hypertension.

7. The method of claim 1 , wherein a value determined from the further testing comprises determining at least one value selected from the values consisting of:
a variability in the composite EtCO 2 value after a 6-minute walk test;
a correlation of the composite EtCO 2 value with hemodynamic markers of PAH for the patient;
a Wells score for the patient; and
a serum D-dimer measurement for the patient.

8. The method of claim 7 , further comprising comparing the value determine from the further testing with the composite EtCO 2 value to assess a therapeutic response of the patient.

9. A method for determining whether additional medical tests need to be conducted for a diagnosis of pulmonary arterial hypertension (PAH) condition in a patient, the method comprising:
measuring end tidal carbon dioxide (EtCO 2 ) of each of a plurality of oral expirations from a patient at rest;
determining a composite EtCO 2 value from each of the plurality of oral expirations;
comparing the composite EtCO 2 value to a range of stored carbon dioxide partial pressure values;
generating a first signal based upon the comparing, the first signal indicative of whether additional medical tests need to be conducted for the diagnosis of pulmonary arterial hypertension; and
providing the generated signal to an indicator, the indicator adapted to respond to the generated signal to provide an output in a human cognizable format.

10. The method of claim 9 , further comprising generating the first signal in response to the comparing by determining that additional medical tests are needed in response to the composite EtCO 2 value being lower than a first predetermined threshold value.

11. The method of claim 10 , wherein the first predetermined threshold value comprises a value between 28 mm Hg and 38 mm Hg, inclusive.

12. The method of claim 11 , further comprising generating the first signal in response to the comparing by determining that additional medical tests are not needed in response to the composite EtCO 2 value being greater than a second predetermined threshold value.

13. The method of claim 12 , wherein the second predetermined threshold value comprises 38 mm Hg.

14. The method of claim 9 , wherein a lower range of the composite EtCO 2 value is indicative of pulmonary arterial hypertension, and a higher range of the composite EtCO 2 value is indicative of pulmonary venous hypertension.

15. The method of claim 9 , wherein a value determined from the further testing comprises a variability in the composite EtCO 2 value after a 6-minute walk test.

16. The method of claim 9 , wherein a value determined from the further testing comprises a correlation of the composite EtCO 2 value with hemodynamic markers of PAH for the patient.

17. The method of claim 9 , wherein a value determined from the further testing comprises a Wells score for the patient.

18. The method of claim 9 , wherein a value determined from the further testing comprises a serum D-dimer measurement for the patient.

19. The method of claim 9 , wherein a value determined from the further testing comprises determining at least one value selected from the values consisting of:
a variability in the composite EtCO 2 value after a 6-minute walk test;
a correlation of the composite EtCO 2 value with hemodynamic markers of PAH for the patient;
a Wells score for the patient; and
a serum D-dimer measurement for the patient.

20. The method of claim 19 , further comprising comparing the value determine from the further testing with the composite EtCO 2 value to assess a therapeutic response of the patient.

Assignees

• Univ Vanderbilt

Inventors

• Hemnes Anna R
• Newman Alexander
• Newman John

Classifications

• A61B5/082

  Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath (A61B5/083, A61B5/091 take precedence) · CPC title

• A61B5/097

  Devices for facilitating collection of breath or for directing breath into or through measuring devices · CPC title

• A61B5/0836 Primary

  Measuring rate of CO2 production · CPC title