Respiratory humidification system

• US 20040060558A1
• Filed: 09/17/2003
• Published: 04/01/2004
• Est. Priority Date: 06/17/1997
• Status: Active Grant

• Current Assignee: Fisher & Paykel Healthcare Limited
• Original Assignee: Fisher & Paykel Limited
• Inventors: Gradon, Lewis George, McPhee, Stephen William, Leonard, Peter John, Seakins, Paul John
• Granted Patent: US 7,263,994 B2
• Time in Patent Office: Days
• US Class Current: 128/203.26
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0841 for sampling
• CPC Class Codes: A61M 16/1075 by influencing the temperature A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/109 the humidifying liquid or the beneficial agent
• CPC Class Codes: A61M 16/1095 in the connecting tubes
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/161 with means for measuring the humidity
• CPC Class Codes: A61M 16/162 Water-reservoir filling system, e.g. automatic
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: G01F 1/684 Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 1/6888 Thermoelectric elements, e.g. thermocouples, thermopiles
• CPC Class Codes: G08B 21/16 Combustible gas alarms
• CPC Class Codes: Y10S 261/65 Vaporizers

Abstract

A flow probe for use in a humidification system is disclosed. The flow probe is adapted to be positioned in a humidified gases flow (for example oxygen or anaesthetic gases) such as that which is provided to a patient in a hospital environment. The flow probe is designed to provide both temperature and flow rate sensing of the gases flow by incorporating two sensors (preferably thermistors) and the shape and alignment of the probe enables accurate readings by reducing the occurrence of condensation on the sensors. A number of possible applications are disclosed wherein the flow sensor is included in humidification control systems which provide a patient with a desired humidity level or simplify the amount of user input required or wherein the flow sensor provides a controller with flow information which may then be used to determine certain, possibly dangerous, conditions (such as incorrect flow sensor placement, breathing circuit disconnected, no water in the humidification chamber or humidity out of required limits).

Claims

1. A breathing circuit component or connector having an interior for conveying respiratory gas comprising

a sensor entry port configured to receive a sensor

a locating depression configured to receive a complementary locating tooth from a sensor, the interconnection of said depression and a tooth providing a predetermined orientation of a sensor within said interior.

2. A breathing circuit component as claimed in claim 1 further comprising a sensor for locating within said port including:

sensor housing adapted for positioning in said gas flow, said sensor housing having a longitudinal axis substantially perpendicular to said humidified gases flow and a sensing end,

a locating tooth configured to mate with said depression

at least one projecting tab, extending laterally from said sensor housing, said at least one projecting tab providing surfaces which enable liquid condensate to disperse away from said sensing end of said sensor housing.

3. A breathing circuit component as claimed in claim 2 wherein said sensor comprise two projecting tabs.

4. A breathing circuit component as claimed in claim 2 or claim 3 wherein said two projecting tab are oppositely positioned around said sensor housing.

5. A breathing circuit component as claimed in claim 2 or claim 3 wherein each said at least one projecting tab is aligned parallel to said gas flow.

6. A breathing circuit component as claimed in claim 2 or claim 3 wherein liquid condensate is dispersed along the lines of intersection between said sensor housing and said at least one tab, there existing a localised area of low surface tension along said lines of intersection.

7. A breathing circuit component as claimed in claim 2 or claim 3 wherein said a sensor comprise two sensor housings, a temperature sensor housing means and a flow rate sensor housing.

8. A breathing circuit component as claimed in claim 7 wherein said temperature sensor housing and said flow rate sensor housing each comprise a temperature dependent resistance.

9. A breathing circuit component as claimed in claim 8 wherein temperature dependent resistance is occasionally heated to a predetermined difference temperature above the temperature of said gases flow, and the power required to maintain said predetermined difference temperature providing an indication of the flow rate of said gas.

10. A breathing circuit component as claimed in claim 7 wherein said flow rate sensor housing is exposed at or near the sensing end while said temperature sensor housing is encapsulated at or near the sensing end of the temperature sensor housing.

11. A breathing circuit component as claimed in claim 9 wherein said temperature and flow rate sensor housing are spaced across said gas flow in order that heat produced from said flow rate sensor housing has substantially minimal effect on said temperature sensor housing.

12. A breathing circuit component as claimed in claim 11 wherein said flow rate sensor housing is positioned up stream of said temperature sensor housing in order that heat produced by said flow rate sensor housing does not effect said temperature sensor housing.

13. A breathing circuit component as claimed in claim 2 or claim 3 wherein said gases flow is channelled within a conduit of known cross-sectional area, at least in the region adjacent said sensor, and is provided with said sensor entry port adapted to receive said sensor, the positioning of said temperature and flow rate sensor housing relative to said gas flow being controlled by the interconnection of said locating depression and tooth.

14. A breathing circuit component or connector having an interior for conveying respiratory gas comprising

a gas inlet communicating with said interior configured to connect to an outlet of a humidifier or other breathing assistance apparatus,

a gas outlet communicating with said interior and configured to connect to a conduit,

a sensor entry port configured to receive a sensor

a locating depression configured to receive a complementary locating tooth from a sensor, the interconnection of said depression and a tooth providing a predetermined orientation of a sensor within said interior.

15. A breathing circuit component as claimed in claim 14 wherein sensor entry port comprises an annular cylinder having an passage communicating with and extending from said interior, said passage substantially perpendicular to said interior.

16. A breathing circuit component as claimed in claim 15 wherein said locating depression comprising a notch in the end of said cylinder distant said interior.

17. A breathing circuit component as claimed in claim 16 wherein said notch is substantially “

V”

shaped.

18. A breathing circuit component as claimed in claim 17 wherein the base of said “

V”

shaped notch is rounded.

19. A breathing circuit component as claimed in claim 18 wherein the diameter of said passage ensures a substantially airtight seal against a sensor located therein.

20. A breathing circuit component as claimed in claim 19 wherein said inlet including an exterior surface comprising a tapered male portion configured to connect to a tapered female portion of an inner surface of an outlet of a humidifier, or other breathing assistance apparatus.

21. A breathing circuit component as claimed in claim 20 wherein outlet including an inner surface configured to form a substantially airtight seal against an exterior surface of a conduit.

22. A breathing circuit component as claimed in claim 21 wherein said inner surface and said exterior surface of said conduit are permanently bonded.

23. A breathing circuit component as claimed in claim 22 further comprising a flow sensor having a substantially cylindrical exterior configured to form an airtight seal against said passage, a sensing end and a locating tooth configured to mate with said locating depression and locate said sensing end in a predetermined location or orientation within said interior.

24. A breathing circuit component as claimed in claim 23 wherein said tooth is substantially “

V”

shaped.

25. A breathing circuit component as claimed in claim 24 wherein the base of said “

V”

shaped tooth is rounded.