METHOD AND ARRANGEMENT FOR DETERMINING SAMPLE FLOW VOLUME

• US 20110067480A1
• Filed: 08/18/2010
• Published: 03/24/2011
• Est. Priority Date: 09/24/2009
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: HIETALA, Mika
• Granted Patent: US 8,333,111 B2
• Time in Patent Office: Days
• US Class Current: 73/23.3
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: G01F 22/02 involving measurement of pressure
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath

Abstract

A method for determining a sample flow volume is disclosed herein. The method includes withdrawing the sample flow at a first and second flow rate from a gas flow, measuring a concentration of at least one gas component and measuring at least one of an airway pressure and flow. The method also includes generating first measurement results based on the concentration, generating second measurement results based on the at least one of the airway pressure and flow and setting a suitable point of comparison. The method further includes determining a first and second time delay between the point of comparison of the first and second measurement results of the first and second flow rate, providing information about the first and second sample flow rate and determining the sample volume based on differences between the first and second time delay. A corresponding arrangement is also provided.

Claims

1. A method for determining a sample flow volume comprising:

withdrawing a sample flow at a first and second flow rate from a gas flow;

measuring a concentration of at least one gas component of the sample flow;

measuring at least one of an airway pressure and flow;

generating first measurement results based on said measuring the concentration;

generating second measurement results based on said measuring at least one of said airway pressure and flow;

setting a suitable point of comparison both among said first and second measurement results;

determining a first time delay between said point of comparison of said first and second measurement results of said first flow rate;

determining a second time delay between said point of comparison of said first and second measurement results of said second flow rate;

providing information about said first and second flow rate; and

determining the sample volume based on differences between the first and second time delay.

2. The method according to claim 1, wherein said measuring the concentration of at least one gas component of the sample flow and said measuring at least one of an airway pressure and flow is configured to be made when withdrawing at the first and second flow rate.

3. The method according to claim 1, wherein said generating first measurement results are configured to be made as a function of time and based on said measuring the concentration of the sample flow withdrawn at the first and second flow rate.

4. The method according to claim 1, wherein said generating second measurement results are configured to be made as a function of time and based on said measuring at least one of said airway pressure and flow when withdrawing at the first and second flow rate.

5. The method according to claim 1, wherein determining the sample volume is based on differences between the first time delay at said first flow rate and the second time delay at said second flow rate.

6. The method according to claim 1, wherein the sample flow volume is defined by formula:

Vsample=F1ave*F2ave*Δ

Tdelay/(60*(F1ave−

F2ave)),

where F1ave is the average first flow rate, F2ave is the average second flow rate and Δ

Tdelay is a difference between first and second time delays.

7. The method according to claim 1, further comprising determining a time delay for a normal flow rate based on said sample volume and an average flow rate.

8. The method according to claim 7, wherein said normal flow rate is different from said first and second flow rate.

9. The method according to claim 7, wherein said normal flow rate is one of said first and second flow rate.

10. The method according to claim 8, wherein said normal flow rate is used in ordinary concentration measurements when the sample flow volume is already known.

11. The method according to claim 7, wherein said time delay for the normal flow rate is calculated by the formula:

Tdelay=60*Vsample/Fave,

where Fave is the average flow rate for a normal sample flow.

12. The method according to claim 11, wherein said average flow rate is a mean value of one or more inhalation and expiration period.

13. The method according to claim 11, wherein the calculated Tdelay is approximately a delay between said first measurement results and second measurement results and the exact delay can be determined by waiting for the Tdelay time after a beginning of an inspiration or an expiration of said first measurement results and selecting the nearest beginning of the inspiration or the expiration from said second measurement results respectively.

14. The method according to claim 1, wherein said withdrawing the sample flow at said first flow rate is followed by said measuring the concentration of at least one gas component of the sample flow of the first flow rate and subsequently is made said withdrawing the sample flow at said second flow rate and said measuring the concentration of at least one gas component of the sample flow of the second flow rate.

15. The method according to claim 1, wherein said withdrawing the sample flow at said first flow rate is made substantially simultaneously with said measuring at least one of the airway pressure and flow of said gas flow.

16. The method according to claim 1, wherein said withdrawing the sample flow at said first flow rate, said measuring at least one of the airway pressure and flow of said gas flow when withdrawing at said first flow rate and said measuring the concentration of at least one gas component of the sample flow of the first flow rate are made first followed by said withdrawing the sample flow at said second flow rate, said measuring at least one of the airway pressure and flow of said gas flow when withdrawing at the second flow rate and said measuring the concentration of at least one gas component of the sample flow of the second flow rate.

17. The method according to claim 1, wherein said first flow rate is configured to differ from said second flow rate at least 10 ml/min, more specifically at least 15 ml/min or even more specifically at least 20 ml/min.

18. An arrangement for determining a sample flow volume comprising:

a pump for withdrawing at first and second flow rates along a sampling tube a sample flow from a channel for a gas flow;

an analyzer for measuring a concentration of at least one gas component withdrawn at said first and second flow rates;

a measuring apparatus for measuring at least one of an airway pressure and flow of said gas flow when withdrawing at said first and second flow rate; and

an electronics (21) for generating first measurement results based on the measured concentration of at least one gas component withdrawn at a first and second flow rate and for generating second measurement results based on said at least one of said airway pressure and flow measured while withdrawing at said first and second flow rate and for setting a suitable point of comparison both among said first measurement results and among said second measurement results and for determining a first time delay between said point of comparison of said first measurement results and said point of comparison of said second measurement results of said first flow rate and for determining a second time delay between said point of comparison among said first measurement results and said point of comparison among said second measurement results of said second flow rate and for receiving an information about said first and second flow rate and for determining the sample volume based on differences between the first time delay at said first flow rate and the second time delay at said second flow rate.

19. The arrangement according to claim 18, wherein said electronics is configured to determine a time delay for a normal sample flow rate based on said sample volume and an average flow rate.

20. A method for determining a sample flow volume comprising:

withdrawing a sample flow at a first and second flow rate from a gas flow;

measuring a concentration of at least one gas component of the sample flow when withdrawing at said first and second flow rate;

measuring at least one of an airway pressure and flow of said gas flow when withdrawing at said first and second flow rate;

generating first measurement results as a function of time based on said measuring the concentration of said first and second flow rate;

generating second measurement results as a function of time based on said measuring at least one of said airway pressure and flow of said the first and second flow rate;

setting a suitable point of comparison both among said first measurement results and said second measurement results of the first and second flow rate;

determining a first time delay between said point of comparison of said first measurement results and said point of comparison of said second measurement results of said first flow rate;

determining a second time delay between said point of comparison of said first measurement results and said point of comparison of said second measurement results of said second flow rate;

providing information about said first flow rate and said second flow rate; and

determining the sample volume based on differences between the first time delay at said first flow rate and the second time delay at said second flow rate.