Breathing assistance apparatus

• US 6,918,389 B2
• Filed: 03/14/2001
• Issued: 07/19/2005
• Est. Priority Date: 03/21/2000
• Status: Expired due to Term

• Current Assignee: Fisher & Paykel Healthcare Limited
• Original Assignee: Fisher & Paykel Healthcare Limited
• Inventors: Thudor, Mohammad, Seakins, Paul John, Smith, Malcolm David
• Primary Examiner(s): Dawson, Glenn K.
• Application Number:
  US09/808,567
• Publication Number:
  US 20010050080A1
• Time in Patent Office: 1,588 Days
• Field of Search: 128/200.24, 128/201.13, 12820312-20414, 128/204.17, 128/205.12, 128/206.22, 128/200.14, 128/204.18, 261/129, 261/138, 261/142, 454/339
• US Class Current: 128/203.27
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/08 Bellows; Connecting tubes having means for taking samples G01N1/22; Water traps; Patient circuits
• CPC Class Codes: A61M 16/0875 Connecting tubes
• CPC Class Codes: A61M 16/0883 Circuit type
• CPC Class Codes: A61M 16/10 Preparation of respiratory gases or vapours
• CPC Class Codes: A61M 16/1075 by influencing the temperature A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/1085 after being humidified or mixed with a beneficial agent
• 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 16/142 with semi-permeable walls separating the liquid from the respiratory gas
• 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 2016/003 with a flowmeter
• CPC Class Codes: A61M 2016/102 Measuring a parameter of the content of the delivered gas
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/50 with microprocessors or computers

Abstract

A humidifier and humidity sensor for use with a breathing assistance apparatus. The humidity sensor senses absolute humidity, relative humidity and/or temperature at both the patient end and humidifier end. The humidifier may also include provision to both control independently the humidity and temperature of the gases. Further, a chamber manifold facilitates easy connection of the humidifier to various outlets, inlets and sensors. A heated conduit provides a more effective temperature profile along its length.

Claims

1. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

humidification chamber and having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

a chamber heater provided adjacent said humidification chamber and adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

humidity sensor configured to provide an indication of the absolute humidity of said gases flow at least at one of said humidification chamber and at a point along said conduit in said gases flow,

a controller or processor configured or programmed to receive as inputs said indication of the absolute humidity of said gases flow, estimate a rate of condensation of said gases in said conduit based on said inputs and control said chamber heater based on said rate of condensation to minimise condensation of said gases in said conduit.

2. A humidification apparatus as claimed in claim 1 wherein said conduit includes a conduit heater to heat said gases flow, and said controller or processor is configured to control said conduit heater based on said rate of condensation to minimise condensation of said gases in said conduit.

3. A humidification apparatus as claimed in claim 2 wherein said humidity sensor including a first absolute humidity sensor in substantial proximity to said outlet of said humidification chamber.

4. A humidification apparatus as claimed in claim 3 wherein said conduit having a patient end, distal to said end connected to said outlet of said humidification chamber, and said humidity sensor further comprising a second absolute humidity sensor in substantial proximity to said patient end of said conduit.

5. A humidification apparatus as claimed in claim 4 wherein said estimate of the rate of condensation is based on the difference between the absolute humidity at said outlet of said humidification chamber, as indicated by the output of said first absolute humidity sensor, and the absolute humidity at said patient end of said conduit, as indicated by the output of said second absolute humidity sensor.

6. A humidification apparatus as claimed in claim 5 wherein said controller or processor is configured to:

i) energise said conduit heater depending on at least said estimate of the rate of condensation, to a level appropriate to substantially vaporise any liquid condensate present in said conduit; and

ii) energise said conduit heater depending on at least said estimate of the rate of condensation, to a level appropriate to minimise any condensation of the vapour from said gases in said conduit.

7. A humidification apparatus as claimed in claim 6 wherein said steps (i) and (ii) are repeated continually at regular intervals.

8. A humidification apparatus as claimed in claim 6 wherein said steps (i) and (ii) are alternated at regular intervals.

9. A humidification apparatus as claimed in claim 2 wherein said conduit having a patient end, distal to said end connected to said outlet of said humidification chamber and said apparatus further comprising a first temperature sensor in substantial proximity to said outlet of said humidification chamber and an absolute humidity sensor in substantial proximity to said patient end of said conduit.

10. A humidification apparatus as claimed in claim 2 further comprising at least a temperature sensor and at least one relative humidity sensor providing an indication of the temperature and relative humidity at least at one point in the flow path of said gases flow through said apparatus.

11. A humidification apparatus as claimed in claim 2 wherein further comprising flow sensing means adapted to provide an indication of the rate of flow of said gases flown through said apparatus.

12. A humidification apparatus as claimed in claim 11 wherein said flow sensing means comprising a heated element adapted to maintain a substantially constant temperature and being provided in the flow path of said gases through said apparatus, the heat loss therefrom providing an indication of the rate of flow of said gases.

13. A humidification apparatus as claimed in claims 1 or 2 wherein said humidity sensor further comprising a disposable cover providing a substantial barrier to microorganisms between said flow of gases and said humidity sensor.

14. A humidification apparatus as claimed in claims 1 or 2 wherein said humidity sensor further comprising porous disposable cover means for providing porous material as a substantial barrier to microorganisms between said flow of gases and said absolute humidity sensor.

15. A humidification apparatus as claimed in claim 9 further comprising a conduit heater adapted to heat said gases flow in said conduit and/or said conduit, and said controller or processor configured to energise said conduit heater depending on at least said estimate of the rate of condensation, at a level appropriate to minimise any condensation of the vapour from said gases in said conduit as well as convey said gases flow to said patient or other person in need of such gases substantially at a predetermined level of absolute humidity.

16. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber and having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber including wet heating means adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber and dry heating means adapted to directly heat said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, including insulation to minimise the rate of heat energy lost by said gases flow in said conduit,

a controller configured to energise said wet heating means and said dry heating means to achieve a desired level of absolute humidity and to minimise the condensation of the vapour from said gases in said conduit.

17. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber and having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a regulated conduit heater adapted to regulate the temperature profile of said gases flow along said conduit and/or of said conduit, to substantially coincide with a predetermined profile, wherein said regulated conduit heater comprising at least one section of negative temperature coefficient material wherein the localised electrical resistance of said section is negatively related to the localised temperature.

18. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber and having an inlet and an outlet to allow said eases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a regulated conduit heater adapted to regulate the temperature profile of said gases flow along said conduit and/or of said conduit, to substantially coincide with a predetermined profile wherein said regulated conduit heater comprising a plurality of sections of positive temperature coefficient material wherein the localised electrical resistance of each said section is positively related to the localised temperature section and at least two electrical conductors running along said conduit, each said conductor being electrically connected to a separate portion of each said section and each said section being electrically isolated from all other sections except for the connection through each said conductor.

19. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a regulated conduit heater adapted to regulate the temperature profile of said gases flow along said conduit and/or of said conduit, to substantially coincide with a predetermined profile wherein said conduit further comprising an inspiratory conduit in fluid communication with said outlet of said humidification chamber, a connector means in fluid communication with said inspiratory conduit, a flexible tube extension in fluid communication with said connector and a patient interface in fluid communication with said flexible tube extension adapted to convey said gases flow to said patient.

20. A humidification apparatus as claimed in claim 19 wherein said flexible tube extension including a flexible tube extension heater with at least one section of positive temperature coefficient material wherein the localised electrical resistance of said material is positively related to the localised temperature.

21. A humidification apparatus as claimed in claims 19 or 20 wherein said patient interface comprising a patient interface heater including at least one section of positive temperature coefficient material wherein the localised electrical resistance of each said section of said material is positively related to the localised temperature.

22. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a regulated conduit heater adapted to regulate the temperature profile of said gases flow along said conduit and/or of said conduit, to substantially coincide with a predetermined profile further comprising a humidity sensor for providing an indication of the absolute humidity of said gases flow at said outlet of said humidity chamber.

23. A humidification apparatus as claimed in claim 22 wherein further comprising a temperature sensor for providing an indication of the temperature of said gases flow at said outlet of said humidification chamber.

24. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a regulated conduit heater adapted to regulate the temperature profile of said gases flow along said conduit and/or of said conduit, to substantially coincide with a predetermined profile wherein said conduit comprising a double walled inspiratory conduit and said regulated conduit heater comprising the provision of warm fluid circulated between the inner wall and outer wall of said double walled inspiratory conduit.

25. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

chamber heater provided adjacent said humidification chamber adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a regulated conduit heater adapted to regulate the temperature profile of said gases flow along said conduit and/or of said conduit, to substantially coincide with a predetermined profile wherein said predetermined profile relates to a substantially constant temperature along the length of said conduit.

26. A method for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

transferring water vapour or humidity to gases passing through a chamber,

conveying said gases flow to said patient or other person in need of such gases from said chamber, and

sensing the absolute humidity of said gases flow at one point along its flow path,

estimating a rate of condensation of said gases based on said absolute humidity and controlling the transferred humidity based on said rate of condensation to minimise condensation of said gases.

27. A method as claimed in claim 26 further comprising the step of heating said gases flow at least at one point along its flow path, and controlling the transferred heat based on said rate of condensation to minimise condensation of said gases.

28. A method as claimed in claim 27 wherein said absolute humidity is sensed in substantial proximity to said chamber.

29. A method as claimed in claim 28 wherein said absolute humidity is also sensed in substantial proximity to a patient.

30. A method as claimed in claim 29 wherein said estimate of the rate of condensation is based on the difference between the absolute humidity at said outlet of said chamber, and the absolute humidity at said patient.

31. A method as claimed in claim 30 further comprising the steps of:

i) heating said gases flow depending on at least said estimate of the rate of condensation, to a level appropriate to substantially vaporise any liquid condensate; and

ii) heating said gases flow depending on at least said estimate of the rate of condensation, to a level appropriate to minimise any condensation of the vapour from said gases.

32. A method as claimed in claim 31 said steps (i) and (ii) are repeated continually at regular intervals.

33. A method as claimed in claim 31 wherein said steps (i) and (ii) are alternated at regular intervals.

34. A method as claimed in claim 27 wherein the temperature of said gases is sensed in substantial proximity to the outlet of said chamber and the absolute humidity is sensed in substantial proximity to said patient.

35. A method as claimed in claim 34 further comprising the steps of heating said gases, and controlling the transferred heat depending on at least said estimate of the rate of condensation, at a level appropriate to minimise any condensation of the vapour from said gases as well as convey said gases flow to said patient or other person in need of such gases substantially at a predetermined level of absolute humidity.

36. A method as claimed in claim 27 wherein the temperature and relative humidity at least at one point in the flow path of said gases flow is sensed.

37. A humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:

a humidification chamber and having an inlet and an outlet to allow said gases flow to pass through said humidification chamber,

a chamber heater provided adjacent said humidification chamber and adapted to vaporise liquid water in said humidification chamber in order to provide water vapour to said gases flow passing through said humidification chamber,

a conduit connected to said outlet of said humidification chamber to convey said gases flow to said patient or other person in need of such gases, and

a humidity sensor configured to provide an indication of the absolute humidity of said gases proximate said outlet,

a controller or processor configured or programmed to receive as inputs said indication of the absolute humidity of said gases flow, and energise said chamber heater based on said absolute humidity to achieve a predetermined absolute humidity at said outlet, and configured or programmed to vary said predetermined absolute humidity to substantially avoid condensation in said conduit.