Leak determination in a breathing assistance system

• US 9,254,369 B2
• Filed: 12/15/2014
• Issued: 02/09/2016
• Est. Priority Date: 02/10/2010
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Jourdain, Cedric, Bernadet, Olivier
• Primary Examiner(s): DOUGLAS, STEVEN O
• Application Number:
  US14/570,106
• Publication Number:
  US 20150090265A1
• Time in Patent Office: 421 Days
• Field of Search: 128/202.22, 128/204.18, 12820421-20423, 128/200.24
• US Class Current: 1/1
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0057 Pumps therefor
• CPC Class Codes: A61M 16/0063 Compressors
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 16/04 Tracheal tubes catheters in general A61M25/00
• CPC Class Codes: A61M 16/0666 Nasal cannulas or tubing devices for improving normal breathing through the nose A61F5/08; nose filters A62B23/06; outside holding devices A61M25/02
• CPC Class Codes: A61M 16/0883 Circuit type
• CPC Class Codes: A61M 16/20 Valves specially adapted to medical respiratory devices
• CPC Class Codes: A61M 2016/0015 inhalation detectors
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/003 with a flowmeter
• CPC Class Codes: A61M 2016/0033 electrical
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient

Abstract

Systems and methods for estimating a leak flow in a breathing assistance system including a ventilation device connected to a patient are provided. Data of a flow waveform indicating the flow of gas between the ventilation device and the patient is accessed. A specific portion of the flow waveform is identified, and a linear regression of the identified portion of the flow waveform is performed to determine an estimated leak flow in the breathing assistance system.

Claims

1. A breathing assistance system including a ventilation device for delivering respiratory gases to a patient, the breathing assistance system having a controller for estimating a leak flow by:

monitoring a flow of gas between the ventilation device and the patient, wherein the monitored flow of gas is represented by a flow waveform;

determining a first representative flow rate for a first period of the flow waveform;

determining a second representative flow rate for at least a second period of the flow waveform;

defining a steady phase portion of the flow waveform to include the first period and the second period when the second representative flow rate varies from the first representative flow rate by less than a predetermined amount; and

performing an interpolation of the steady phase portion of the flow waveform to determine an estimated leak flow.

2. The breathing assistance system according to claim 1, in response to determining the estimated leak flow, the controller is further configured to control at least one of one or more operational parameters of the breathing assistance system.

3. The breathing assistance system according to claim 1, further comprising:

identifying a specific portion of the flow waveform comprising the first period and the second period by determining that a flow variation in the flow waveform falls within a predetermined variation threshold.

4. The breathing assistance system according to claim 1, further comprising:

determining a third representative flow rate for a third period of the flow waveform; and

defining the steady phase portion to include the first period, the second period, and the third period when the third representative flow rate varies from the first representative flow rate by less than the predetermined amount.

5. The breathing assistance system according to claim 1, wherein the second period immediately precedes the first period.

6. The breathing assistance system according to claim 4, wherein the third period immediately precedes the second period, and wherein the second period immediately precedes the first period.

7. The breathing assistance system according to claim 1, further comprising:

determining a third representative flow rate for a third period of the flow waveform; and

defining the steady phase portion to include the first period and the second period when the third representative flow rate varies from the first representative flow rate by more than the predetermined amount.

8. The breathing assistance system according to claim 1, wherein the interpolation is linear regression.

9. A method for estimating a leak flow in a breathing assistance system including a ventilation device connected to a patient, the method comprising:

monitoring a flow of gas between the ventilation device and the patient, wherein the monitored flow of gas is represented by a flow waveform;

determining a first representative flow rate for a first period of the flow waveform;

determining a second representative flow rate for at least a second period of the flow waveform;

defining a steady phase portion of the flow waveform to include the first period and the second period when the second representative flow rate varies from the first representative flow rate by less than a predetermined amount; and

performing an interpolation of the steady phase portion of the flow waveform to determine an estimated leak flow in the breathing assistance system.

10. The method according to claim 9, further comprising:

in response to determining the estimated leak flow, controlling at least one operational parameter of the ventilation device.

11. The method according to claim 9, wherein identifying the specific portion of the flow waveform comprises:

determining that the steady phase portion of the flow waveform has a flow variation within a predetermined variation threshold.

12. The method according to claim 9, further comprising:

determining a third representative flow rate for a third period of the flow waveform; and

defining the steady phase portion to include the first period, the second period, and the third period when the third representative flow rate varies from the first representative flow rate by less than the predetermined amount.

13. The method according to claim 9, wherein the second period immediately precedes the first period.

14. The method according to claim 12, wherein the third period immediately precedes the second period, and wherein the second period immediately precedes the first period.

15. The method according to claim 9, further comprising:

determining a third representative flow rate for a third period of the flow waveform; and

defining the steady phase portion to include the first period and the second period when the third representative flow rate varies from the first representative flow rate by more than the predetermined amount.

16. The method according to claim 9, wherein the interpolation is linear regression.

17. A ventilation device comprising:

at least one processor; and

at least one memory storing computer-readable instructions that when executed by the at least one processor cause the ventilation device to;

monitor a flow of gas between the ventilation device and the patient, wherein the monitored flow of gas is represented by a flow waveform;

determine a first representative flow rate for a first period of the flow waveform;

determine a second representative flow rate for at least a second period of the flow waveform;

define a steady phase portion of the flow waveform to include the first period and the second period when the second representative flow rate varies from the first representative flow rate by less than a predetermined amount; and

perform an interpolation of the steady phase portion of the flow waveform to determine an estimated leak flow in the ventilation device.

18. The ventilation device according to claim 17, the computer-readable instructions further causing the ventilation device to:

in response to determining the estimated leak flow, control at least one of one or more operational parameters of the ventilation device.

19. The ventilation device according to claim 17, the computer-readable instructions further causing the ventilation device to:

determine a third representative flow rate for a third period of the flow waveform; and

define the steady phase portion to include the first period, the second period, and the third period when the third representative flow rate varies from the first representative flow rate by less than the predetermined amount.

20. The ventilation device according to claim 19, wherein the third period immediately precedes the second period, and wherein the second period immediately precedes the first period.