Humidifier for a respiratory assistance device, a respiratory assistance device and related methods and apparatus

Abstract

A humidification apparatus for a respiratory assistance device is provided wherein the humidification apparatus is configured such that, in use, light impinges on a humidification material to generate localised heating of liquid molecules around the humidification material to generate vapour. A respiratory assistance device comprising a humidifier and related methods and apparatus are also provided. Arrangements are provided for generating vapour by impinging light on a humidification material, wherein, in some embodiments, the humidification material comprises a metallic and/or carbon based material, particularly in the form of nanoparticles.

Claims

1. A humidification apparatus for a respiratory assistance device, the humidification apparatus comprising: a first conduit and a second conduit, wherein the first and second conduits are generally coaxially arranged, wherein at least a portion of a wall between the first and second conduits allows vapour to pass between the first conduit and the second conduit, wherein the first conduit and/or at least a portion of a wall thereof comprises a humidification material, and wherein the humidification apparatus is configured such that in use, light impinges on the humidification material to generate localised heating of liquid molecules around the humidification material to generate vapour.

2. The humidification apparatus of claim 1, wherein the humidification material comprises a metallic and/or carbon based material.

3. The humidification apparatus of claim 2, wherein the metallic and/or carbon based material is in the form of nanoparticles.

4. The humidification apparatus of claim 3, wherein the nanoparticles are provided within a fluid, the fluid disposed in the first conduit.

5. The humidification apparatus of claim 3, wherein the nanoparticles are disposed on or within a wall of the first conduit.

6. The humidification apparatus of claim 1, wherein the first conduit is located inside the second conduit.

7. The humidification apparatus of claim 1, wherein the second conduit is located inside the first conduit.

8. The humidification apparatus of claim 1, further comprising a light source.

9. The humidification apparatus of claim 8, wherein the light source is provided inside the first conduit.

10. The humidification apparatus of claim 8, wherein the light source is provided between the walls of the first and second conduits.

11. The humidification apparatus of claim 8, wherein the light source is provided external to the first and second conduits.

12. The humidification apparatus of claim 1, further comprising one or more light guiding structures.

13. A humidification apparatus for a respiratory assistance device, the humidification apparatus comprising: a first conduit and a second conduit, wherein the first and second conduits are generally coaxially arranged, wherein vapour is configured to pass between the first conduit and the second conduit, wherein the first conduit and/or at least a portion of a wall thereof comprises a metallic and/or carbon based material, wherein the metallic and/or carbon based material is in the form of nanoparticles, and wherein the humidification apparatus is configured such that in use, light impinges on the metallic or carbon-based material to generate localised heating of liquid molecules around the metallic or carbon-based material to generate vapour.

14. The humidification apparatus of claim 13, wherein the nanoparticles are provided within a fluid, the fluid disposed in the first conduit.

15. The humidification apparatus of claim 13, wherein the nanoparticles are disposed on or within a wall of the first conduit.

16. The humidification apparatus of claim 13, wherein the first conduit is located inside the second conduit.

17. The humidification apparatus of claim 13, wherein the second conduit is located inside the first conduit.

18. The humidification apparatus of claim 13, further comprising a light source.

19. The humidification apparatus of claim 13, further comprising one or more light guiding structures.

20. A humidification apparatus for a respiratory assistance device, the humidification apparatus comprising: a first conduit and a second conduit, wherein vapour is configured to pass from the first conduit to the second conduit, wherein the first conduit and/or at least a portion of a wall thereof comprises a humidification material, and wherein the humidification apparatus is configured such that in use, light impinges on the humidification material to generate localised heating of liquid molecules around the humidification material to generate vapour.

21. The humidification apparatus of claim 20, wherein the humidification material comprises a metallic and/or carbon based material.

22. The humidification apparatus of claim 20, wherein the humidification material is in the form of nanoparticles.

Description

DRAWING DESCRIPTION

(1) A number of embodiments of the invention will now be described by way of example with reference to the drawings in which:

(2) FIG. 1 is a schematic of a prior art respiratory assistance device incorporating a humidifier;

(3) FIG. 2 is a schematic side view of a first embodiment of a respiratory assistance device and humidifier in accordance with the invention;

(4) FIG. 3 is a schematic side view of a second embodiment of a respiratory assistance device and humidifier in accordance with the invention;

(5) FIG. 4 is a schematic side view of a third embodiment of a respiratory assistance device in accordance with the invention; and

(6) FIG. 5 is a schematic side view of a third embodiment of a respiratory assistance device and humidifier in accordance with the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) Throughout the description like reference numerals will be used to refer to like features in different embodiments.

(8) The humidifier in accordance with the present invention may be used with any respiratory assistance device, or as part of any respiratory assistance system, where a gas stream requires humidification enrichment.

(9) An example respiratory assistance system can be seen in FIG. 1 and comprises a humidifier. The system is a humidified Continuous Positive Airway Pressure (CPAP) system 1 which provides humidified and pressurised gas to a patient 3 via a patient interface 5 which in this example comprises a nasal mask. Supply gas is provided by a blower arrangement 7, via a gas delivery conduit 3A to a humidifier 9 comprising a chamber 11 filled with a liquid to be evaporated. The humidifier 9 comprises a heating plate 12 or heating coil or the like, generally below the chamber 11. The vapour generated passes from the chamber 11 into the gas flow path via gas delivery conduit 3B connected to the patient interface 5.

(10) While the invention is described below in relation to this system, it will be appreciated that the humidifier in accordance with the present invention may be used with any type of respiratory assistance system, including, for example, a Variable Positive Airway Pressure (VPAP) system or a Bi Level Positive Airway Pressure (BiPAP) system. Further, alternative means may be provided for generating the gas stream and/or for transporting the stream from the humidifier chamber to the patient i.e., alternative conduit and/or patient interface arrangements may be used. Those skilled in the art would be familiar with selecting different, known components to build the system for a particular implementation based on a patient's diagnosis and preferences, as well as due to cost and technical constraints.

(11) Referring to FIG. 2, part 21 of a respiratory assistance device according to an embodiment of the invention is shown. The respiratory assistance device comprises a gas flow path in the form of a gas delivery conduit 3 (which includes the headspace in the shown chamber) having an inlet 25 to receive gas from a source of supply gas (not shown) and an outlet 27 to deliver gas to a patient interface (not shown). The patient interface may, for example, comprise a full or partial face mask or a nasal cannula. The supply gas is driven along the gas flow path 3 and delivered to the patient to pressurise the patient's airway. For example, blower arrangement 7 of FIG. 1 may be configured to couple to inlet 25, and conduit 3B and nasal mask 5 of FIG. 1 may be configured to couple to outlet 27.

(12) An optional gas heater 29 is provided to preheat the supply gas prior to entering the gas flow path. As noted hereinbefore, the novel humidifier of the invention provides more localised heating of a portion of the liquid inside the humidifier chamber and as such, additional heating may be required of the gas stream to prevent or reduce condensation being generated within the chamber or shortly after exiting the chamber. Conduits including heater elements are known in the art and may, for example, include a heater coil of resistance wire incorporated into the wall of the conduit.

(13) The humidifier 31 is provided downstream of the gas heater 29, and upstream of a second optional gas heater 33 arranged to maintain the temperature of the gas after being humidified by the humidifier 31. The second optional gas heater 33 may be configured in a similar manner to the first optional gas heater.

(14) The humidifier 31 is arranged to provide vapour, which may be but is not limited to water vapour, to the gas stream in the gas flow path 3, prior to delivery of the gas to the patient. The vapour is generated via a nanoparticle based heating arrangement. In particular, the humidifier 31 comprises a chamber 35 containing humidification liquid 36, typically water, and metallic and/or carbon based nanoparticles indicated schematically of 38. The nanoparticles are subject, in use, to light which may be ambient light, or light from an artificial light source. At least a portion of the contents of the chamber are exposed to light such that light impinges on the nanoparticles to generate localised heating of liquid molecules in the chamber and generate vapour for use by the respiratory assistance device.

(15) The energy of the received light heats the nanoparticles to a relatively high temperature, preferably to or above the boiling point of the liquid. This heat vaporises the liquid in a region surrounding each nanoparticle. The vapour rises and passes from the chamber 35 into the gas stream in the gas flow path 3. The process continues until the light source is removed.

(16) In this example, the chamber 35 is generally cylindrical. The chamber 35 may be pre-charged with liquid and/or nanoparticles prior to mounting the chamber on or in the humidifier 31, or these may be added subsequently. The chamber 35 and/or humidifier 31 may be removably mounted on a part of the respiratory assistance system.

(17) The chamber 35 may be mounted within an outer housing 37, the inner walls 39 of which may be light reflective. In the illustrated embodiment, a light source is provided in the form of a lamp 41 located at the base of the chamber 35 in the void between the chamber 35 and the outer housing 37. The light from the light source 41 is incident on the base and side walls of the chamber 35 as indicated by the arrows 42. The reflective inner walls 39 assist in delivering the light to the chamber 35. It will be appreciated that the light source may be positioned elsewhere and/or more than one light source may be provided, the intensity or number of which in use may be varied depending on the required level of humidification.

(18) In this example, the walls of the chamber 35 are sufficiently transparent that the light from the light source 41 passes through the walls 39 of the chamber 35 and is incident on the nanoparticles and liquid contained in the chamber 35. This initiates fluid vapour generation via the light heating the nanoparticles, as described above. The generated vapour passes from the chamber 35 into the gas stream 3 and humidifies the gas prior to delivery to the patient. The second gas heater 33 is arranged to heat the humidified gas to reduce or alleviate condensation along the path to the patient interface.

(19) In an alternative arrangement, the light source may be positioned inside the chamber 35, including being positioned in a wall thereof. While housing 39 may still be constructed as shown in FIG. 2, alternatively, the walls of the chamber 35 may be reflective.

(20) According to a yet further alternative, a light source may be configured external to the chamber 35 so as to direct at least a portion of the light emitted thereby through a light transmissible portion of the chamber 35 wall. At least some of the remainder of the wall of the chamber 35 may be reflective to retain light inside the chamber.

(21) According to some embodiments, the light source(s) are configured to emit pulsed light with the ratio of ON:OFF times preferably being adjustable to control the level of humidification. Such ratios may be predetermined based on experimental data. Alternatively, the humidity inside and/or downstream of the chamber may be monitored and used to control the light source accordingly e.g. a longer ON time and/or shorter OFF time may be used if increased humidity is required.

(22) A nanoparticle retention device 43 is provided in the gas flow path 3, downstream of the humidifier chamber 35. The device 43 is arranged to prevent nanoparticles in the gas stream from passing through the device 43 and into the patient interface and the patient airway.

(23) The device 43 may be electromagnetic and arranged to generate an electromagnetic field that attracts or repels the nanoparticles. Alternatively or additionally, the device 43 may incorporate a barrier or filter arranged to allow vapour to pass, but retain the nanoparticles. The device 43 may alternatively be positioned at or adjacent the outlet of the chamber, or within the chamber.

(24) A wide variety of types of light source may be used such as an LED or LED cluster for example. The light source need not be located at the chamber 35 and could be remote therefrom. In that instance the light may be delivered to the chamber 35 via a fibreoptic cable or cables for example.

(25) The light source may be external to the outer housing 37 and may comprise ambient light. In that instance the outer housing 37 of the humidifier 31 may be arranged to allow light to reach the chamber 35. In such embodiments, at least a portion of the wall of the housing 37 may substantially prevent or selectively substantially prevent light from entering the housing 37 so as to prevent the generation of vapours when not required.

(26) The nanoparticle heating arrangement generates vapour relatively quickly due to the rapid increase in temperature of the nanoparticles when subject to light, and also due to the side effect that the vapour is generated only in close proximity to each nanoparticle. Thus, the bulk of the body of the liquid may not be heated, or at least not heated significantly, heating being localised to the nanoparticles. This reduces the energy consumption of the humidifier 31 as compared to using a standard heating plate or heating coil. This effect also lessens the material requirements of the chamber 35, allowing a material to be selected that need not be capable of withstanding the relatively high temperatures of prior art humidifiers. Further, many existing chambers include a metallic base plate to assist in heat transfer from the heater plate positioned thereunder in use. The present invention enables the complete chamber to be formed from plastics, for example, simplifying and reducing the cost of production.

(27) The humidifier of the invention provides greater and more rapid control of the amount of vapour generated, and therefore the humidity of the gas supplied to the patient since it can be changed relatively quickly, and repeatedly, allowing the humidity level in the gas stream to be accurately tailored and/or varied to the patient's varying needs by changing characteristics of the light source(s) (e.g. intensity or brightness. ON time, number of light sources used) and/or by adjusting the path of the light generated thereby (e.g. using mirrors or light blocks or other optical means to control whether and/or how much light is directed at the chamber 35 contents and/or whether and/or to what extent that light is retained inside the chamber 35).

(28) A further benefit is that the fluid consumption may be reduced, as the vapour generated is more precisely controlled as compared to a prior art humidifier since the lags associated with heating a larger body of water are not present, at least to the same degree, in arrangements incorporating the invention.

(29) The above therefore provides an improved humidifier for a respiratory assistance device which uses nanoparticles to generate localised heat, and therefore localised vapour for humidifying enrichment of a gas stream.

(30) The humidifier 31 may be arranged to be mounted on an existing respiratory assistance device in place of a prior art humidifier. The humidifier 31 comprises the components necessary to generate vapour and deliver the vapour into the gas flow path. The humidifier 31 therefore comprises at least the chamber 35 and connections between the chamber 35 and the gas flow path 3. The humidifier 31 may comprise an integral light source, and a power connection for connection to an electrical power source which may be integral or couplable to the respiratory assistance device.

(31) The liquid to be evaporated and the nanoparticles may be supplied as a humidification fluid comprising a pre-mixture of predetermined amounts of liquid and nano-particles. The chamber 35 may be filled, or refilled, prior to each use. Alternatively the chamber 35 may be supplied prefilled with a humidification liquid. Once used, the chamber 35 may be removed from the humidifier 35 and replaced. Alternatively, a user may fill the chamber 35 with a requisite amount of liquid and then add nano-particles thereto. This process may be reversed. Note that the nanoparticles may be re-used and a liquid such as water simply added to the chamber, as required.

(32) Referring to FIG. 3, an alternative humidification part 51 of a respiratory assistance device is shown comprising a gas flow path in the form of a delivery conduit 3. In this example, a gas heat exchanger 52 is provided between the source of supply gas and the patient interface. The heat exchanger 52 is arranged to transfer heat to/from the supply gas to the patient, and the expiratory gas from the patient in use.

(33) In this example, the humidifier 31 comprises a relatively small chamber 55 adjacent the heat exchanger 52 and adjacent the patient interface (not shown), that is, at the patient end of the gas flow path 3.

(34) A light source is provided remotely and light delivered along a fibre optic cable 57 which extends inside the delivery conduit 3 to the heat exchanger 52. The light is delivered by the fibre optic cable 57 to the small chamber 55 to generate vapour as described above.

(35) Optionally, the delivery conduit 3, or the outer material of the fibre optic cable 57, or an intermediate coaxial tube (not shown), may be provided with nanoparticles which are subject to light from the fibre optic cable 57, or from a further light source, to generate heat as well as, or alternatively to, generating vapour for humidification. This heat can be used in the heat exchanger 52 to heat the supply gas prior to delivery to the patient. The nanoparticles may be embedded in the material of the delivery conduit 3, the fibre optic cable 57 or in part of the heat exchanger 52, light being delivered as required to the location of the nanoparticles. Thus, it is envisaged that heating from nanoparticles could be used instead of, or to supplement, a more common resistance wire type electrical heating arrangement. Eliminating the need for resistance wire type heaters can be particularly useful in some hospital environments to reduce the emission of electromagnetic radiation which may interfere with some equipment. For example, during a medical scan such as a MRI scan. Alternatively they may be of value where a suitable electrical power source is not locally available. Yet further, such embodiments can provide for improved safety by removing the need for electrically conducting wires, at least in the region of the vapours.

(36) In a modification of the above, liquid may be supplied to the patient, using capillary action, from a centralised or remote fluid source, whereby liquid is drawn from a reservoir as it is used.

(37) Referring to FIG. 4, a combined heating and humidifying tube comprises a gas delivery conduit 3 inside of which is provided a heating/light tube 53. The supply gas flows along the delivery conduit 3, outside the heating/light tube 53. Liquid contained in the tube 53 is heated via light incident on nanoparticles also in tube 53 to generate vapour which passes from the tube 53 into the gas delivery conduit 3. Thus, the walls of the tube 53 are preferably permeable to evaporated liquid (i.e., allow at least a portion of the vapours to pass from inside the tube 53 to the gas stream in conduit 3) but preferably substantially inhibits liquid from passing through the wall of the tube 53. The material of the tube 53 may comprise a Sympatex or similar material for example.

(38) Referring to FIG. 5, a modified heating light tube 53 is of coaxial form comprising an outer tube 53A, and inside of which is provided a fibre optic cable 53B through which light passes. Fluid and nanoparticles are provided inside the outer tube 53A but outside the fibre optic cable 53B. The material of the outer tube 53A is chosen to allow evaporated liquid to pass through the wall of the outer tube 53A and into the gas stream in the delivery conduit 3, but to retain the nanoparticles and liquid within the outer tube 53A. The material of the outer tube 53A may comprise a sheath of a Sympatex or similar material for example. The fibre optic cable 53B comprises at least one light delivery device arranged to transmit the light from the fibre optic cable into the tube 53. The light delivery device may comprise a ridge or the like including other surface contouring which causes light to exit the fibre optic cable 53B and heat the nanoparticles in the outer tube 53A. The liquid may be transported along the outer tube 53A by capillary action or via a powered pumping arrangement.

(39) The gas delivery conduit 3 and the outer tube 53A may be sufficiently transparent to allow ambient or external light to pass into the outer tube 53A to heat the nanoparticles. The device may then be used in an unpowered mode for transportation or at another time where use of electrical power may not be possible, safe, available or practical. Alternatively, at least a portion of the conduit 3 and/or the outer tube 53A may substantially inhibit light passing therethrough so as to provide for greater control by removing variations in light level caused by changes in the level of ambient light.

(40) The nanoparticles may be arranged to provide heat as well as humidity. The nanoparticles could therefore be embedded into the wall of the delivery conduit 3 and/or the outer tube 53A.

(41) With continued reference to FIGS. 2 and 3, the nanoparticle retention device 43 may be provided with a filter of a barrier material such as Sympatex material. Such a material has a porous structure with pores sized to allow liquid vapour to pass/diffuse into the supply gas path, but to block the nanoparticles. Such a material can be used in any other part of the humidifier 31 or respiratory devices 21, 51 where it is desired to separate the nanoparticles from the stream supplied to the patient.

(42) An electric field may be used to control the dispersion and circulation of the nanoparticles within the liquid, and may be used as the primary method of retention of the nanoparticles within the evaporative system.

(43) Whilst it is envisaged that suitable parts of the humidifier 33 may be sufficiently transparent that light can be transmitted through those parts into the fluid to be heated, it may alternatively be desirable to make such parts non-light transmitting in order to avoid any unwanted heating of the fluid due to external or ambient light. For example, if a co-axial type tube is used, the inner sheath may be formed from a non-transparent material.

(44) Where it is desired to use the heating effect of nanoparticles to generate heat otherwise than for controlling humidification of the supply gas, the nanoparticles may be embedded into part of the material of the device, such that when subject to light, heat is generated to heat the material. For example, the nanoparticles may be embedded in the walls of the gas delivery tube 3, or one or both tubes of a coaxial tube.

(45) Unless the context clearly requires otherwise, throughout the description, the words comprise, comprising, and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of including, but not limited to.

(46) Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention. The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features. Furthermore, where reference has been made to specific components or integers of the invention having known equivalents, then such equivalents are herein incorporated as if individually set forth.

(47) Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.