SYSTEM AND METHOD FOR DETECTING RESPIRATORY EVENTS

• US 20080097234A1
• Filed: 09/28/2007
• Published: 04/24/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Nicolazzi, Pascal, Nadjafizadeh, Hossein, Gaudard, Yves, Grillier-Lanoir, Veronique, Flemmich, Bruno
• Granted Patent: US 8,366,631 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0063 Compressors
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 2016/0015 inhalation detectors
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/003 with a flowmeter
• CPC Class Codes: A61M 2230/40 Respiratory characteristics

Abstract

A method for determining the respiratory flow of a patient receiving bi-level respiratory therapy is provided. The method may include measuring the total air flow through a breathing area at a time approximately when the patient has completed exhalation, measuring the pressure in the breathing area, determining a constant representing a corrective flow factor by dividing the measured total air flow by the square root of the measured pressure, and determining the patient'"'"'s respiratory flow by subtracting from a subsequent total air flow the product of constant and the square root of a subsequent pressure.

Claims

1. A method for determining the respiratory flow of a patient receiving bi-level respiratory therapy, the method comprising:

measuring the total air flow through a breathing area at a time approximately when the patient has completed exhalation;

measuring the pressure in the breathing area;

determining a constant representing a corrective flow factor by dividing the measured total air flow by the square root of the measured pressure; and

determining the patient'"'"'s respiratory flow by subtracting from a subsequent total air flow the product of constant and the square root of a subsequent pressure.

2. A method according to claim 1, wherein measuring the total air flow comprises measuring the total air flow about five times during a period of about 100 milliseconds preceding the beginning of an inspiratory phase.

3. A method according to claim 2, wherein measuring the pressure in the breathing area comprises measuring the pressure in the breathing area about five times during a period of about 100 milliseconds preceding the beginning of an inspiratory phase.

4. A system for determining the respiratory flow of a patient receiving bi-level respiratory therapy, the system comprising:

a breathing device defining a breathing area;

a flow sensor operable to measure the total air flow through the breathing area at a time approximately when the patient has completed exhalation;

a pressure sensor operable to measure the pressure in the breathing area; and

a processor operable to;

determine a constant representing a corrective flow factor by dividing the measured total air flow by the square root of the measured pressure; and

determine the patient'"'"'s respiratory flow by subtracting from a subsequent total air flow the product of constant and the square root of a subsequent pressure.

5. A system according to claim 4, wherein the flow sensor is operable to measure the total airflow by measuring the total air flow about five times during a period of about 100 milliseconds preceding the beginning of an inspiratory phase.

6. A system according to claim 5, wherein the pressure sensor is operable to measure the pressure by measuring the pressure about five times during a period of about 100 milliseconds preceding the beginning of an inspiratory phase.

7. A method for detecting a respiratory event of a patient receiving bi-level respiratory therapy, the method comprising:

measuring the total air flow through a breathing area at a time approximately when the patient has completed exhalation;

measuring the pressure in the breathing area;

determining a constant representing a corrective flow factor by dividing the measured total air flow by the square root of the measured pressure;

determining the patient'"'"'s respiratory flow by subtracting from a subsequent total air flow the product of the constant and the square root of a subsequent pressure;

determining an average flow for a plurality of breathing cycles; and

determining the occurrence of a respiratory event by determining if the patient'"'"'s respiratory flow is less than a predetermined percentage of the determined average flow.

8. A method according to claim 7, wherein determining the occurrence of a respiratory event includes determining if the patient'"'"'s respiratory flow remains less than a predetermined percentage of the determined average flow for a predetermined period of time.

9. A method according to claim 7, wherein the predetermined percentage is about eighty percent.

10. A method according to claim 7, wherein the predetermined number of preceding peak to peak breathing cycles is about eight.

11. A method according to claim 7, wherein the predetermined period of time is about ten seconds plus five eighths of a patient'"'"'s breath cycle time.

12. A method according to claim 7, wherein the predetermined percentage is about fifty percent.

13. A method according to claim 7, wherein the predetermined period of time is about ten seconds.

14. A system for detecting a respiratory event of a patient receiving bi-level respiratory therapy, the system comprising:

a breathing device defining a breathing area;

a flow sensor operable to measure the total air flow through the breathing area at a time approximately when the patient has completed exhalation;

a pressure sensor operable to measure the pressure in the breathing area; and

a processor operable to;

determine a constant representing a corrective flow factor by dividing the measured total air flow by the square root of the measured pressure;

determine the patient'"'"'s respiratory flow by subtracting from a subsequent total air flow the product of the constant and the square root of a subsequent pressure;

determine an average flow for a plurality of breathing cycles; and

determine the occurrence of a respiratory event by determining if the patient'"'"'s respiratory flow is less than a predetermined percentage of the determined average flow.

15. A system according to claim 14, wherein determining the occurrence of a respiratory event includes determining if the patient'"'"'s respiratory flow remains less than a predetermined percentage of the determined average flow for a predetermined period of time.

16. A system according to claim 14, wherein the predetermined percentage is about eighty percent.

17. A system according to claim 14, wherein the predetermined number of preceding peak to peak breathing cycles is about eight.

18. A system according to claim 14, wherein the predetermined period of time is about ten seconds plus five eighths of a patient'"'"'s breath cycle time.

19. A system according to claim 14, wherein the predetermined percentage is about fifty percent.

20. A system according to claim 14, wherein the predetermined period of time is about ten seconds.