Patent Description:
Humidifiers are often used in respiratory therapy to provide humidified breathing gas to the airways of a person suffering from any of a number of respiratory illnesses or conditions. Such therapies may include but are not limited to pressure therapy, such as continuous positive airway pressure (CPAP) therapy and non-invasive ventilation (NIV) therapy.

CPAP therapy can be used to treat obstructive sleep apnoea (OSA), a condition in which a patient's airway intermittently collapses during sleep, preventing the patient from breathing for a period of time.

CPAP therapy involves the delivery of a supply of continuous positive air pressure to the airway of the patient via a respiratory interface. The continuous positive pressure acts as a splint within the patient's airway, which secures the airway in an open position such that the patient's breathing and sleep are not interrupted.

However, the breathing gas provided during pressure therapy can dry the airways of a patient, which leads to patient discomfort. Respiratory pressure therapy systems, such as CPAP systems and NIV systems, therefore typically include humidifiers in which a body of water is heated and air is passed over the water, where it is humidified before being delivered to a patient receiving respiratory pressure therapy. The most common method of heating the body of water is through the use of a thermally conductive heater plate that is heated by an electrically powered heating element. However, actively heating water using a heater plate has a number of disadvantages. For example, it may require a relatively large amount of power (approximately <NUM>-<NUM> W, or <NUM>-<NUM> W, depending on the device) to power a heating element to generate the necessary level of heat. Such a high power requirement increases the cost to operate the humidifier. The high power requirement can also limit the portability of the humidifier because the device must either be constantly connected to mains power, or if battery powered, requires a large (and typically expensive) battery to operate for an extended period of time.

Another disadvantage is that an active heating system, whether using a conductive method (such as by using a heater plate) or an inductive method, requires electronics to control and operate the heating system, which adds to the complexity of the humidifier; increases the cost to produce the humidifier; and also requires the size of the humidifier to be sufficiently large to include the heating system with control electronics in an appropriate arrangement within the humidifier. In addition, software is required to operate the electronic controls for the heating system, which further increases the complexity and cost of the humidifier.

Active heating systems also tend to have an inherent time delay between when the heating system is turned on and when the humidification system is operating at the set or desired level. For example, the heater plate must heat the entire body of water to an elevated temperature before a substantial increase in humidity results, which can take up to <NUM> minutes or more.

Another disadvantage with humidifiers that require a heating system for humidification is the associated hazard risk. For example, a heating element creates the opportunity for a heat or temperature hazard to be present to the user.

<CIT> discloses a humidifier with a heating element, having an internal wick and wick frame located within the humidification chamber for holding the wick in place. The wick frame has 'baffles' for lengthening the air flow path along the wick. It is an object of the present invention to provide a humidification device or system that goes at least some way towards overcoming the disadvantages of known humidification devices or systems, or to at least provide the public with a useful alternative.

Described herein is a humidification device for use in CPAP, wherein the device comprises: a wick chamber for supporting a wick and comprising at least a gas inlet; a non-heated fluid chamber for holding fluid to be placed in contact with the wick; wherein the fluid chamber is configured to allow fluid from the fluid chamber to wet the wick to humidify gas passing through or over the wick.

In one form, the wick chamber is held within the fluid chamber and the wick chamber comprises a foraminous structure for holding the wick within the wick chamber and diffusing gas flow through or over the wick. Optionally, the wick chamber comprises a baffle wall comprising diffusion apertures of varying sizes to diffuse gas through or over the wick. In another form, the humidification device may comprise a blade diffuser to diffuse gas from the gas inlet through or over the wick.

In one form, the gas inlet is located on the side of the wick chamber to direct gas through the wick from the side of the wick. The gas inlet may enter the wick chamber at a transition region comprising a curved radius between the gas inlet and the chamber at a transition region comprising a curved radius between the gas inlet and an external wall of the wick chamber to encourage gas entering the wick chamber to diffuse by exploiting a Coanda effect.

In one form, the humidification device comprises a wick supported by the wick chamber. Different regions of the wick may have a different thickness to other regions.

The technology provides a humidification device for use in CPAP, wherein the device comprises: a wick chamber for supporting a wick; a gas inlet to the wick chamber; and a diffusion system for directing or controlling gas flow through the device. The diffusion system comprises a diffuser to diffuse gas flowing from the gas inlet and into the wick chamber substantially evenly through or over the wick. The gas inlet is located on the side of the wick chamber, preferably to direct gas through the wick from the side of the wick.

The wick chamber comprises a foraminous structure for supporting the wick within the wick chamber and diffusing gas flow through or over the wick. Preferably, the wick chamber comprises a baffle wall comprising diffusion apertures of varying sizes to diffuse gas flow through or over the wick.

In one form, the gas inlet enters the wick chamber at a transition region comprising a curved radius between the gas inlet and an external wall of the wick chamber to encourage gas entering the wick chamber to diffuse by exploiting a Coanda effect. Optionally, the humidification device comprises a blade diffuser to diffuse gas from the gas inlet through the wick.

Described herein is a humidification module configured for retrofit insertion into a humidification device, wherein the humidification module comprises a wick chamber for supporting a wick within the wick chamber, and wherein the humidification module comprises at least one attachment member to detachably attach the humidification module to a flow generator to generate a flow of gas through the humidification module.

Also described herein is a humidification control system comprising: a humidification device comprising a gas inlet and a gas outlet, a wick chamber for supporting a wick, the wick chamber being in fluid communication with the gas inlet and the gas outlet and being configured to provide humidified gas to the gas outlet of the humidification device, a gas bypass connected to the gas inlet and the gas outlet and configured to allow gas to bypass the wick chamber from the gas inlet to the gas outlet, and a controller to control the amount of gas that bypasses the wick chamber. Preferably, the humidification control system further comprises a wick supported by the wick chamber.

Further described herein is a humidification device for use in CPAP, wherein the device comprises; a wick chamber for supporting a wick; a fluid chamber to hold a reservoir of fluid; and a fluid flow path connecting the wick chamber and the fluid chamber to allow fluid to be fed from the fluid chamber to the wick chamber to wet the wick.

In one form, the wick chamber and the fluid chamber each comprise an opening and wherein the device further comprises a removable seal configured to detachably attach to the wick chamber, the fluid chamber, or both, to seal the openings of the wick chamber, the fluid chamber, or both. Preferably, the humidification device further comprises a wick supported by the wick chamber.

Also described herein is a humidification device for humidifying a flow of breathing gas, wherein the humidification device comprises: a fluid chamber having a gas inlet and a gas outlet, wherein the breathing gas flows through the fluid chamber from the gas inlet to the gas outlet,
a wick supported within the fluid chamber such that the flow of breathing gas through the fluid chamber passes through the wick, the wick configured to wick fluid within the fluid chamber across the wick, wherein the wick comprises; a wick body, and a hollow region, wherein the hollow region of the wick is downstream of the gas inlet, and wherein the gas outlet is downstream of the hollow region of the wick. Optionally, the wick includes a wick inlet downstream of the gas inlet and upstream of the hollow region.

In one form, a wick chamber is located within the fluid chamber and comprises a foraminous structure for supporting the wick within the fluid chamber. Preferably, the wick chamber is configured to attach to the fluid chamber. In one form, the wick chamber includes an internal chamber wall, an external chamber wall, a base and a lid. The wick is optionally supported between the internal chamber wall and the external chamber wall.

In one form, the hollow region of the wick is a cuboid shape. In another form, the hollow region of the wick is a cylindrical shape.

In one form, a first thickness of the wick near the gas inlet is thinner than a second thickness of the wick near the gas outlet.

Preferably, in use, fluid within the fluid chamber is maintained at or below ambient temperature.

Also described herein is a kit comprising: a flow generator comprising a non-humidified gas circuit to deliver non-humidified gas to a patient; a humidification module detachably attachable to the flow generator and comprising a humidified gas circuit to deliver humidified gas to a patient; and a control system to control the amount of gas that flows from the flow generator through the humidified gas circuit and the amount of gas that flows from the flow generator through the non-humidified gas circuit.

Further described herein is a humidification device for use in CPAP, wherein the device comprises: a wick chamber for supporting a wick and comprising at least one gas inlet; a fluid chamber for holding fluid to be placed in contact with the wick; wherein the fluid chamber is configured to allow fluid from the fluid chamber to wet the wick; and a flow generator configured to cause a flow of gas to pass through or over the wick to produce a flow of humidified gas, wherein the flow of humidified gas is at a temperature equal to ambient temperature plus any temperature increase due to heating caused by the flow generator.

Also described herein is a humidification device for a respiratory pressure therapy device comprising: a fluid chamber comprising a gas inlet and a gas outlet; and a wick supported within the fluid chamber, the wick comprising a wick body having two spaced apart opposed portions, wherein the wick is at least partially disposed between the gas inlet and the gas outlet of the fluid chamber.

In one form, the wick is disposed within the fluid chamber to cause gas that enters the fluid chamber via the gas inlet to pass through or over a first of the spaced apart portions of the wick body, across the space between the two portions and then through or over a second of the spaced apart portions of the wick body before exiting the fluid chamber via the gas outlet. Preferably, the wick body comprises a hollow region that defines the space between the two opposed portions of the wick body. Optionally, the wick body comprises a curved external surface. In one form, the wick body comprises a curved external surface and wherein the hollow region of the wick body is defined by a curved internal wall to form an annular wick.

In one form, the wick body comprises a first linear portion. The wick body may also comprise a second linear portion. Optionally, the first linear portion is disposed at an angle to the second linear portion. In one form, the angle is greater than <NUM> degrees.

In one form the wick body comprises wicking elements. Optionally, the wick body comprises a lattice of wicking elements. Preferably, the wicking elements are fibrous.

Also disclosed herein is a humidification device for use in CPAP, wherein the device comprises: a wick; a non-heated fluid chamber for holding fluid in contact with the wick; and a gas inlet to the fluid chamber, wherein the fluid chamber and wick are configured to humidify gas passing through the wick.

Preferably, gas passes through the wick at approximately ambient conditions.

In one form, the fluid chamber comprises a connection structure for directly connecting to a self-supporting wick. Optionally, the self-supporting wick is a sufficiently rigid sintered wick. The self-supporting wick may be directly connected to fluid within the fluid chamber.

Preferably, the fluid chamber comprises a foraminous structure for holding the wick within the fluid chamber and diffusing gas flow through or over the wick.

In one form, the humidification device further comprises a wick chamber for supporting the wick within the fluid chamber, wherein the wick chamber comprises a baffle wall comprising diffusion apertures of varying sizes to diffuse gas flow through or over the wick.

Preferably, the gas inlet is located to direct gas through the wick from the side of the wick.

Optionally, the gas inlet is relatively large compared to the side of the wick. For example, the gas inlet may comprise an opening to the wick that is at least one third of the size of the side surface of the wick.

In one form, a plenum is located between the gas inlet and the wick.

Optionally, the gas inlet enters the fluid chamber at a transition region comprising a curved radius between the gas inlet and fluid chamber wall to encourage gas entering the fluid chamber to diffuse by exploiting a Coanda effect.

In one form, the humidification device further comprises a blade diffuser to diffuse gas from the gas inlet through the wick.

Optionally, different areas of the wick have a different thickness.

Also disclosed herein is a humidification device for use in CPAP, wherein the device comprises: a wick; a wick chamber for supporting the wick; a gas inlet to the wick chamber; and a diffusion system for directing or controlling gas flow through the device.

Preferably, the diffusion system comprises a diffuser for diffusing gas flowing from the gas inlet and into the wick chamber substantially evenly through the wick.

The wick chamber comprises a foraminous structure for holding the wick within the wick chamber and diffusing gas flow through or over the wick.

Optionally, the wick chamber comprises a baffle wall comprising diffusion apertures of varying sizes to diffuse gas flow through or over the wick.

In one form, the gas inlet is located to direct gas through the wick from the side of the wick.

In one form, the humidification device further comprises a plenum located between the gas inlet and the wick.

In one form, the gas inlet enters the wick chamber at a transition region comprising a curved radius between the gas inlet and chamber wall to encourage gas entering the wick chamber to diffuse by exploiting a Coanda effect.

Optionally, the humidification device further comprises a blade diffuser to diffuse gas from the gas inlet through the wick.

In one form, different areas of the wick have a different thickness.

Further disclosed herein is a humidification control system comprising: a humidification device comprising a gas inlet and a gas outlet, a wick humidifier connected to the gas inlet and the gas outlet and configured to deliver humidified gas to the gas outlet of the humidification device, a gas bypass connected to the gas inlet and the gas outlet and configured to allow gas to bypass the wick humidifier from the gas inlet to the gas outlet, and a controller to control the amount of gas that bypasses the wick humidifier.

Optionally, the controller is connected to the gas inlet.

Also disclosed herein is a humidification device for use in CPAP, wherein the device comprises a wick; a wick chamber to hold the wick; a fluid chamber to hold a reservoir of fluid; and a fluid flow path connecting the wick chamber and the fluid chamber to allow fluid to be fed from the fluid chamber to the wick chamber to wet the wick.

Optionally, the device is configured to allow fluid to flow from the fluid chamber to the wick chamber to maintain a substantially constant water level in the wick chamber.

In one form, the wick chamber and the fluid chamber each comprise an opening and the device further comprises a removable seal configured to detachably attach to the wick chamber and the fluid chamber to seal the openings of the wick chamber and the fluid chamber.

The wick chamber opening may be configured to allow a wick to be placed into and removed from the wick chamber.

The fluid chamber opening may be configured to allow fluid to be poured into and out of the fluid chamber.

Embodiments of systems, components and methods of assembly and manufacture will now be described with reference to the accompanying figures, wherein like numerals refer to like or similar elements throughout. Several embodiments, examples and illustrations are disclosed below.

Certain terminology may be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as "above" and "below" refer to directions in the drawings to which reference is made.

Terms such as "top", "bottom', "upper", "lower", "front", "back", "left", "right", "rear", and "side" describe the orientation and/or location of portions of the components or elements within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the components or elements under discussion. Moreover, terms such as "first", "second", "third", and so on may be used to describe separate components. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import.

Referring to <FIG>, the invention relates to a humidification device <NUM> and a humidification system <NUM> for the delivery of humidified breathing gas, such as air, to a patient. The humidification device or system comprises a humidifier. The humidification system may comprise an in-built humidifier or a detachable humidifier.

In one form, the humidification device and system may be configured for use in CPAP or other positive pressure respiratory therapy, such as NIV.

The humidification device <NUM> may comprise a heating system to heat fluid within a fluid chamber. In another form, the humidification device may be devoid of such a heating system and may operate at approximately ambient temperature, which may include a temperature slightly lower than or slightly above ambient temperature. In other words, the humidification device may be a non-heated humidification device that humidifies gas passing through or over a wick at approximately ambient conditions. For example, the humidification device may provide passive, non-active humidification through an absence of an intentional form of heating or through an absence of a controlled heating system to heat fluid in a fluid reservoir within the device. Optionally, the humidification device is configured to humidify breathing gas without the assistance of a designated electric heating system to heat fluid in the fluid reservoir. Where the device includes an electronic control system, such as a system for operating the flow generator, heat from the energy created by the control system may raise the temperature of the fluid in the fluid reservoir or gas within the device, but only slightly above ambient temperature.

The humidification device <NUM> may comprise a flow generator/blower <NUM>, or may be configured to attach to a flow generator <NUM>, to blow breathing gas <NUM> through the device <NUM> in order to humidify the breathing gas <NUM> before delivering the breathing gas to a patient. The flow generator <NUM> may add some heat to the gas entering the humidification device, causing the temperature of the gas to be raised slightly above ambient temperature. This slightly heated gas may cause some marginal increase of temperature to the fluid in the fluid reservoir.

The humidification device <NUM> may comprise a wick <NUM> and a fluid chamber <NUM> for holding fluid <NUM> that may be at least partially absorbed by the wick <NUM>. In one form, the wick <NUM> may be held within the fluid chamber <NUM>, as shown best in <FIG>, so that fluid within the fluid chamber <NUM> wets the wick <NUM> within the chamber <NUM>. In another form, as shown best in <FIG>, the wick <NUM> may be held in or supported by a wick chamber/wick support structure <NUM> that is in fluid communication with the fluid chamber <NUM> so that fluid <NUM> from the fluid chamber <NUM> flows to the wick chamber <NUM> and wets the wick <NUM> in the wick chamber <NUM>. In one form, the wick chamber <NUM> may be attached to the fluid chamber <NUM>.

The wick <NUM> may comprise a structure that aids wetting by the fluid <NUM> and/or that aids gas flow <NUM> through or over the wick. The wick <NUM> may be wet by at least partially absorbing or soaking up the fluid <NUM> and/or by being at least partially coated by the fluid <NUM>.

In one form, the wick structure may comprise a matrix or lattice of wicking elements, which makes it easier to cause a portion of the gas flow <NUM> to flow through or over the wick <NUM> and a portion of the gas <NUM> to flow across the wicking elements of the wick to evaporate fluid <NUM> from the wick <NUM>. The wicking elements may be small fibrous constituents of the wick <NUM> so that fluid <NUM> from the fluid chamber <NUM> is encouraged to spread across the wicking elements. The wicking elements may be arranged to provide apertures between at least some of the wicking elements to allow gas flow between wicking elements. The wick <NUM> may comprise a large number of wicking elements to create a large surface area for gas <NUM> to pass across the wick <NUM> and to therefore improve the rate at which fluid evaporates from the wick <NUM> and humidifies the gas <NUM>. The term `across the wick' as used in this specification includes gas flow through the wick and over the wick, unless otherwise indicated.

The fluid <NUM> may be water, an alternative fluid (such as a medicinal fluid), or a combination of water and an alternative fluid.

The humidification device <NUM> comprises a gas inlet <NUM> that directs gas <NUM> across the wick <NUM>.

The wick <NUM> is configured to draw fluid, from the fluid chamber <NUM>, up and through the body of the wick <NUM> via capillary action so that the wick is kept moist. The wick <NUM> acts to increase the humidity of breathing gas <NUM> passing across the wick <NUM>. In some cases, the use of a wick <NUM> can increase the relative humidity of airflow through the humidification device to <NUM>%.

The wick <NUM> may be shaped and dimensioned to provide a relatively large surface area over which the fluid <NUM> can be dispersed in order to increase the humidifying efficiency of the wick <NUM>. The wick <NUM> may have a substantially uniform structure or an irregular structure.

In one form, the wick comprises a wick body comprising two spaced apart portions. In one form, the wick body may comprise a hollow region that defines the space between the first and second portions of the wick body.

The wick body may be of any suitable shape. For example, the wick body may comprise a curved external surface or a linear external surface. In one form, the wick body may comprise two or more linear external surfaces forming linear portions of the wick body that are disposed at an angle to each other, such as at an angle of about or greater than <NUM>°. In one form, first and second linear surfaces meet at an angle of about or greater than <NUM>°. The hollow region may be defined by an internal surface comprising a curved wall, or one or more linear walls joined together, or a combination of curved and linear walls. Where the wick body comprises two spaced apart opposed portions, each having a linear internal surface (such as a wick body having a box-section shape), the two portions may be referred to as first and second linear portions. The first and second linear portions may be joined together by side portions, which may also be linear, but may otherwise be curved. In one form, the first and second linear portions may be disposed at an angle to each other of about or greater than <NUM>°. In one form, the first and second linear portions are joined together at an angle of about or greater than <NUM>°.

In one form, as shown in <FIG>, the wick <NUM> takes the shape of a hollow, tubular cylinder or annular shape. In another form, the wick may comprise any suitable curved shape, such as a U-shape. In yet another form, as shown in <FIG>, the wick <NUM> may take the shape of a hollow polygon or rectangular prism having multiple linear external surfaces that meet together at an angle of about <NUM>°. In other configurations, the wick <NUM> could take the general shape of a hollow oval, or any other polygon and/or regular or irregular three-dimensional configuration. The hollow region of the wick is defined by one or more interior walls that form an interior surface of the hollow region. The shape of the hollow region may be the same as or different from the external shape of the wick. For example, the wick may comprise a cuboid external shape with a cuboid hollow region defined by four evenly sized internal walls. Alternatively, the wick may comprise a cuboid external shape with a tubular hollow region formed by a single curved internal wall. In alternate configurations, the wick <NUM> could simply be a planar two-dimensional face with a depth that forms a sheet of material, having a desired thickness.

In one form, as shown in <FIG> and <FIG>, the wick may comprise at least one internal space 131b, such as a substantially hollow region or core. For example, the wick <NUM> may be substantially cylindrical or polygonal, such as cuboid, and may comprise a space or hollow region 131b within the wick, preferably at the centre of the wick <NUM>. In another form, the hollow region 131b may be offset from centre, or the wick may comprise multiple hollow regions that may be evenly or unevenly spaced through the body of the wick. The hollow region(s) 131b may extend completely through the wick <NUM> from the top of the wick to the bottom. Or one or more hollow regions 131b may form a depression or recess in the top of the wick <NUM> so that the bottom of the wick comprises a substantially continuous surface. The internal space(s) 131b further increase the exposed surface area of the wick <NUM> and help to increase the rate of evaporation of fluid from the wick to increase the rate at which gas <NUM> is humidified by the humidification device <NUM>. In another form, as shown in <FIG> and <FIG>, the wick <NUM> may comprise a substantially consistent or uniform structure throughout the wick.

Optionally, the wick <NUM> comprises at least one opening or recess forming a wick inlet/wick opening portion 131a through which gas may be directed across the wick <NUM>. Gas can be directed into the internal space(s) 131b via the wick opening 131a prior to being directed through the wick <NUM> to increase the surface area of the wick <NUM> that is exposed to the gas. The wick opening is greater than the pore size of the material from which the wick is made and is distinct from apertures created by the structural arrangement of the wick, such as apertures formed between wicking elements of a wick having a lattice structure.

The humidification device <NUM> also comprises a gas outlet through which the humidified gas <NUM> can be provided to a patient.

The humidification device <NUM> may operate as follows:
Firstly, ambient air/breathing gas <NUM> is drawn into the device <NUM> via an inlet.

Secondly, the ambient gas <NUM> passes through the powered flow generator <NUM>. The gas may be caused to heat slightly (by only a few degrees Celsius) due to heat transfer from the energy released from the powered flow generator <NUM> and energy from other forces within the device, such as friction, compression, and the like.

Thirdly, the flow generator <NUM> blows the gas <NUM> across the wick <NUM>, such as by blowing the gas through and over the wicking elements. Fluid <NUM> in and on the wick <NUM>, particularly fluid on the wicking elements, is evaporated, which increases the humidity of the gas <NUM>. At the same time, the evaporation of the fluid causes the temperature of the gas to be reduced slightly (i.e. due to the latent heat of vaporisation). The temperature decrease is typically only slight (a few degrees Celsius). The energy contained in the gas and provided incidentally by forces around the flow generator and the heating effect of electronics in the device, helps to maintain the temperature of the fluid reservoir <NUM> to approximately ambient temperature, preventing fluid <NUM> from within the fluid reservoir <NUM> from continuously cooling due to the loss of energy/heat as a result of evaporation.

Fourthly, the gas <NUM> is delivered to the patient via the gas outlet.

The humidification device <NUM> is therefore able to humidify ambient gas <NUM> passing through the device <NUM> without deliberately heating the gas <NUM> and therefore without including components in the device <NUM> (such as a heater) for the purpose of heating the gas <NUM> passing through the device <NUM>.

In one form, as shown in <FIG>, the humidification device <NUM> comprises a fluid chamber <NUM> that includes a gas inlet <NUM>, a gas outlet <NUM>, a suspension bracket/fluid reservoir support structure/lid <NUM>, and a tub/bucket/fluid reservoir <NUM> for holding a reservoir of fluid <NUM> and that attaches to the lid <NUM>. The humidification device also comprises a wick <NUM> held within or supported by a wick chamber <NUM>.

The fluid chamber lid <NUM> is located above the fluid chamber tub or reservoir <NUM>. The wick chamber <NUM> may be attached to and suspended from the lid <NUM>, as shown in <FIG> and <FIG>, so that the wick chamber <NUM> is located within the tub/reservoir <NUM> of the fluid chamber <NUM>, as shown in <FIG> and <FIG>. In one form, the wick chamber <NUM> is detachably attached to the lid <NUM>. The wick chamber <NUM> may be detachably attachable to the lid <NUM> of the fluid chamber <NUM> via a snap fit configuration (such as by providing one or more rigid connectors on the wick chamber <NUM> that are configured to snap fit into one or more rigid connectors on the fluid chamber lid <NUM>), interference fit (such as by providing one or more rigid connectors on the wick chamber that are configured to fit into one or more plastically deformable connectors on the fluid chamber lid or vice versa), threaded screw fit, or by any other suitable attachment system. Alternatively, the entire wick chamber <NUM> may be removable and replaceable.

The wick <NUM> may be held within the wick chamber <NUM>, which supports the wick <NUM> within the fluid chamber <NUM>. The wick chamber <NUM> may comprise an internal/interior chamber wall <NUM>, an external/exterior chamber wall <NUM>, and a base <NUM>, as shown in <FIG>. Optionally, the wick chamber <NUM> may also comprise a lid <NUM> configured to be attached to the lid <NUM> of the fluid chamber <NUM>. In another form, one or more walls <NUM>, <NUM> of the wick chamber <NUM> may be configured to attach to the fluid chamber lid <NUM>. In one form, the wick chamber <NUM> may be configured to detachably attach to the lid <NUM>. In this configuration, the wick <NUM> may be sandwiched between the internal <NUM> and external <NUM> chamber walls and is supported by the base <NUM> and located beneath the wick chamber lid <NUM> or fluid chamber lid <NUM>, as the case may be.

The wick chamber <NUM> also comprises at least one gas inlet <NUM> in fluid communication with the fluid chamber gas inlet <NUM>. In this configuration, breathing gas from the flow generator <NUM> is blown through the fluid chamber gas inlet <NUM> and through the wick chamber gas inlet <NUM> before being directed across the wick <NUM>, such as through a wick inlet portion 131a. The gas flow may diffuse upon entering the wick chamber <NUM> and before passing across the wick <NUM>, as shown in <FIG>. This configuration provides an unimpeded inlet for gas to flow from a flow generator <NUM> to the wick <NUM>, before the gas is emitted from the wick chamber <NUM> through at least one gas outlet and then through the fluid chamber gas outlet <NUM>. Preferably, the wick chamber gas inlet(s) <NUM> and gas outlet(s) are arranged so that breathing gas passes across a significant portion of the wick <NUM> before exiting the wick chamber <NUM>. The wick chamber <NUM> may comprise a gas outlet that is located substantially opposite to the gas inlet <NUM> to encourage gas <NUM> to pass across the wick, from one side to the other, before exiting the wick chamber <NUM>. In another form, as shown in <FIG>, the wick chamber comprises a grille-like structure that has multiple openings. Each opening may form a gas outlet for the wick chamber <NUM>.

The fluid chamber gas outlet <NUM> may be located substantially opposite the fluid chamber gas inlet <NUM> or the gas outlet <NUM> may be located closer to the gas inlet <NUM>. For example, the gas outlet <NUM> may be located at an angle to the gas inlet <NUM>, such as an angle between approximately <NUM>° and <NUM>° from the gas inlet <NUM>. In another form, the gas outlet may be located on the fluid chamber lid or offset from a central point of the gas inlet. For example, the gas outlet may be centred at a point above or below the central point of the gas inlet.

In one form, as shown in <FIG> and <FIG>, the wick <NUM> comprises a body comprising a hollow region. The wick <NUM> is positioned within the wick chamber <NUM> so that the hollow region of the wick <NUM> is downstream of the fluid chamber gas inlet <NUM> and the fluid chamber gas outlet <NUM> is downstream of the hollow region of the wick. Where the wick comprises a wick inlet portion <NUM>1a, the wick inlet is downstream of the fluid chamber gas inlet <NUM> and upstream of the hollow region.

Fluid <NUM>, such as water, transfers from the wick <NUM> to the breathing gas, increasing the humidity of the breathing gas before the breathing gas exits through the gas outlet <NUM> and is directed to the patient.

In one form, as shown in <FIG>, and <FIG>, the wick <NUM> comprises a tubular cylinder that is located between the internal <NUM> and external <NUM> walls of the wick chamber <NUM>. The diameter of the external chamber <NUM> wall may be greater than the diameter of the internal chamber wall <NUM>. The internal chamber wall <NUM> is preferably spaced substantially equidistant from the external chamber wall <NUM> so that the internal and external chamber walls <NUM>, <NUM> form concentric cylinders, between which the hollow cylindrical wick <NUM> is positioned.

In one form, as illustrated, the ratio of the diameter of the internal wick chamber wall <NUM> to the diameter of the external wick chamber wall <NUM> is uniform at approximately <NUM>:<NUM>. In other forms, the ratio is non-uniform, such as where the internal wall <NUM> is of a different shape to the external wall <NUM> or where the internal wall <NUM> is located off-centre with respect to the external wall <NUM>. In other forms, the ratio between the lateral dimension of the internal and external walls <NUM>, <NUM> may be different to the ratio between the distal dimension of the internal and external walls <NUM>, <NUM>, such as where the wick chamber <NUM> has a rectangular configuration.

In one form, the gas inlet <NUM> of the fluid chamber <NUM> and/or wick chamber <NUM> is located to direct breathing gas through the side of the wick <NUM> so that the gas passes through the thickness of the wick <NUM>, as shown in <FIG>.

The gas inlet <NUM> may be of any suitable size and shape. In one form, the gas inlet <NUM> is relatively large compared to the surface of the wick <NUM> facing the inlet <NUM>. For example, the size of the gas inlet <NUM> may be at least one third of the size of the facing surface of the wick <NUM>. Where the gas inlet <NUM> directs gas through the side of the wick <NUM>, the facing surface of the wick <NUM> is the side surface of the wick <NUM> that is proximate the gas inlet <NUM>. The size of the gas inlet may also effect the diffusion of gas flow across the wick. For example, the larger the inlet, the greater the diffusion of gas entering the wick chamber.

The surface area of the wick <NUM> that is exposed to gas flow has an influence on the amount of humidity that can be provided to the gas flow. For example, if a small surface area of the wick <NUM> is exposed to gas flow (because of a high fluid level within the fluid reservoir), the gas flow may not have an opportunity to evaporate enough fluid <NUM> from the exposed surface of the wick <NUM> to provide a sufficient level of humidification to the gas. Therefore, by providing a larger gas inlet to increase the diffusion of gas across the wick, greater humidification efficiencies may be achieved.

The level of fluid <NUM> in the fluid reservoir/tub lowers over time, as fluid <NUM> is evaporated and provided to the patient. If the fluid level is initially too high, the humidity level will be low at the beginning of a therapy session and will increase over time, as the fluid level drops. The decreasing fluid level increases the surface area of the wick <NUM> that is exposed to gas flow. As the wick surface area increases, the humidity provided to the gas flow also increases - to a point.

Any pronounced increase in the humidity of the gas flow could result in an uncomfortable or undesirable change in conditions for the patient. This problem may be mitigated by providing one or more target fluid level indicators on the fluid chamber tub <NUM> and/or providing one or more target fluid level indicators on the wick chamber <NUM>. For example, indicators may be used to mark the maximum and/or minimum target fluid levels. If the fluid chamber <NUM> is filled within this target range, the surface area of wick <NUM> exposed to gas flow will be such that the humidifying effect is maximized (by effectively saturating the output gas). The humidifying effect may be maximized regardless of the extent to which the fluid level drops, as long as the fluid chamber <NUM> holds at least some fluid to distribute across the wick <NUM>.

Factors that influence the effectiveness of the wick <NUM> per unit surface area, and that therefore effect the optimum fill height of the fluid chamber <NUM> include:.

In one form, the wick chamber <NUM> may assist in diffusing or directing gas blown through the fluid chamber <NUM> and therefore across the wick <NUM>, as shown in <FIG>, <FIG>, <FIG> and <FIG>.

It has been found that the wick humidification device <NUM> is most effective when the incoming gas flow from the gas flow generator <NUM> is evenly distributed across the exposed surface area of the wick <NUM>. This ensures that a large surface area of fluid <NUM> (held within the wick <NUM>) is in contact with the moving gas flow <NUM> to allow evaporating fluid <NUM> from the wick <NUM> to humidify the gas <NUM>. Consequently, the efficiency of the humidification device <NUM> may be maximised by dispersing the flow of gas substantially evenly through the fluid chamber <NUM> and across the wick <NUM> as the gas flow <NUM> enters the fluid chamber <NUM>. Advantageously, it may also be simpler to maintain a fully saturated gas output <NUM> under all input gas flow rates and ambient humidity conditions by dispersing the gas flow across the wick <NUM>.

Evenly dispersing the gas flow <NUM> through the fluid chamber <NUM> may also prevent high velocity gas from passing across only a portion of the wick <NUM>, causing that portion to dry out, which would result in a decreased humidity output. High localised velocities of gas <NUM> passing across only a portion of the wick <NUM> may also produce fluid aerosols, which may undesirably result in bacteria transportation by aerosol, due to the large nature of the aerosolised fluid particles that may harbour bacteria.

The humidification device <NUM> may comprise a dispersion system configured to disperse the gas flow through the fluid chamber <NUM> and/or across the wick <NUM>. Different forms of dispersion system may disperse gas through the device <NUM> in many different ways. For example, one or more components of the device <NUM> may be configured to direct or control gas flow <NUM> through the device <NUM>. In another form, the device <NUM> may comprise a diffuser for diffusing gas flow <NUM> through or over the wick <NUM>. In one form, the device <NUM> may comprise a control system or controller for directing or controlling gas flow through the device <NUM>. The control system/controller may comprise one or more control valves for directing gas flow. In one form, one or more control valves may also act as a diffuser.

In some forms, the wick chamber <NUM> may comprise a foraminous structure for holding the wick <NUM>. Openings formed in the foraminous structure may assist dispersion of gas across the wick. The openings of the foraminous structure may also provide multiple inlets <NUM> and/or outlets <NUM> of the wick chamber through which gas can pass.

In one form, one or each of the internal and external walls <NUM>, <NUM> of the wick chamber <NUM> may form a baffle comprising diffusion apertures <NUM> of varying sizes. The diffusion apertures <NUM> may be of any suitable regular or irregular shape, including but not limited to square, rectangular, circular, triangular, hexagonal, octagonal, oval, elliptical, quadrilateral, or amorphous shapes. The internal and/or external wall <NUM>, <NUM> may comprise different shaped diffusion apertures <NUM> from left to right, top to bottom, or throughout the wall <NUM>, <NUM> in a random or regular arrangement. For example, a lower region 132a, 133a of the internal and/or external walls <NUM>, <NUM> respectively may comprise quadrilateral diffusion apertures <NUM> and an upper region 132b, 133b of the internal and/or external walls <NUM>, <NUM> respectively may comprise circular apertures <NUM>. The external wall <NUM> may comprise different shaped diffusion apertures <NUM> to the internal wall <NUM>.

The wick chamber walls <NUM>, <NUM> may comprise different sized diffusion apertures <NUM>, as shown in <FIG> and <FIG>. <FIG> shows a flattened view of one form of internal wick chamber wall <NUM> comprising diffusion apertures <NUM> of varying sizes. The diffusion apertures <NUM> may be different sizes from left to right, top to bottom, or throughout the wall <NUM>, <NUM> in an irregular or regular arrangement. For example, a lower region 132a, 133a of one or both wick chamber walls <NUM>, <NUM> may comprise larger diffusion apertures <NUM> than an upper region 132b, 133b of one or both walls <NUM>, <NUM>, as shown in <FIG>. In one form, the external wick chamber wall <NUM> may comprise different sized diffusion apertures <NUM> to the internal wick chamber wall <NUM>. For example, the diffusion apertures <NUM> of the external wick chamber wall <NUM> may be smaller or larger than the diffusion apertures <NUM> of the internal wick chamber wall <NUM>.

Also as shown in <FIG>, one region of the internal <NUM> or external <NUM> wall of the wick chamber <NUM> may comprise diffusion apertures <NUM> that are smaller than diffusion apertures at another region of the wall <NUM>, <NUM>. In one form, a region of the internal wall <NUM> comprising smaller diffusion apertures <NUM> may be located substantially opposite to the wick chamber inlet <NUM>. In one form, there may also be fewer diffusion apertures <NUM> in this region than in one or more other regions of the internal wall <NUM> of the wick chamber <NUM>.

In one form, a select region <NUM> of a portion of the internal wall <NUM> substantially opposite the gas inlet <NUM>, such as at the upper portion 132b of the internal wall <NUM>, may comprise smaller diffusion apertures <NUM> and/or a reduced number of diffusion apertures <NUM> than another region or than the rest of the internal wall <NUM>. The diffusion apertures <NUM> in the select region <NUM> may also be smaller in size and/or in number than apertures <NUM> of the external wall <NUM>, so that the select region <NUM> acts as an enhanced baffle that helps to diffuse gas flow through or over the wick <NUM>. This configuration decreases the surface area through which the gas can flow, thereby reducing the volume of gas <NUM> that can pass straight through the portion of the wick <NUM> that is adjacent to the select region <NUM> of the internal wall <NUM>. The gas <NUM> that is unable to pass through the select region <NUM> of the internal wall <NUM> is deflected from the wall <NUM> and dispersed through or over other areas of the wick <NUM> to allow a more even distribution of gas flow <NUM> through or over the wick <NUM>. In one form, the internal wall <NUM> may comprise more than one select region <NUM> to modify the dispersion pattern of gas across the wick <NUM>. In another form, the external wall <NUM> or both the internal and external walls <NUM>, <NUM> comprise at least one select region having diffusion apertures <NUM> that are smaller in size and/or reduced in number compared to other diffusion apertures <NUM> in the external and/or internal walls <NUM>, <NUM>.

<FIG> shows a cross-sectional top view of the fluid chamber <NUM>, wick chamber <NUM>, and wick <NUM>. The internal wall <NUM> of the wick chamber <NUM> comprises a select region <NUM> of a reduced number of diffusion apertures <NUM> to provide an enhanced baffle. The select region <NUM> of the internal wall <NUM> is located substantially opposite the inlet <NUM> to the wick chamber <NUM> so that gas <NUM> is directed through the inlet <NUM> toward the enhanced baffle <NUM>. In one form, the select region/enhanced baffle <NUM> may be located proximate to the gas outlet <NUM> of the fluid chamber <NUM>, as shown in <FIG>.

In one form, the total open area of the select region <NUM> (i.e. the total area the diffusion apertures <NUM> within the select region <NUM>) is between approximately <NUM>% to <NUM>% of the total area of the respective internal or external wall <NUM>, <NUM> of the wick chamber <NUM>.

In one form, the total open area of the select region <NUM> may be between <NUM>% and <NUM>% less than the total open area of one or more other regions of the internal <NUM> and/or external wall <NUM>, as shown in <FIG>. For example, the open area in the select region <NUM> located in the upper portion 132b of an internal wick chamber wall <NUM> may be <NUM>% less than the open area in the lower portion 132a of the internal wall <NUM>.

In one form, the select region <NUM> of reduced diffusion apertures <NUM> (diffusion apertures that are fewer in number and/or smaller in size than diffusion apertures in one or more other regions of the wick chamber) may substantially span the length of the wick chamber <NUM>. Where the wick chamber <NUM> is substantially cylindrical and comprises a hollow interior, as shown in <FIG>, the select region <NUM> may extend around the internal perimeter of the wick chamber <NUM> (as indicated by the dashed lines in <FIG>) and/or around the external perimeter of the wick chamber <NUM>. Where the wick chamber <NUM> is polygonal, the select region <NUM> may extend around the perimeter of the polygon or across at least one front or rear surface of the polygon.

In one form, the select region <NUM> of reduced diffusion apertures <NUM> may span the height of the upper 132b, 133b or lower 132a, 133a portion of the internal and/or external wall(s) <NUM>, <NUM> of the wick chamber <NUM>. In the embodiment shown in <FIG>, the upper portion 133b (and select region <NUM>) of the wick chamber internal wall <NUM> spans approximately <NUM>% of the total height of the internal wall <NUM>. In other forms, the select region <NUM> of reduced diffusion apertures <NUM> may span between approximately <NUM>% to <NUM>% of the total height of an internal <NUM> and/or external wall <NUM> of the wick chamber <NUM>. For example, the upper portion 132b, 133b and/or select region <NUM> may span approximately <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the total height of the internal <NUM> and/or external wall <NUM> of the wick chamber <NUM>. The location and size of the select region <NUM> of reduced diffusion apertures <NUM> may depend on the size and location of the wick chamber inlet <NUM>.

The select region <NUM> may span only a portion of the perimeter of the internal <NUM> and/or external walls <NUM> of a cylindrical wick chamber <NUM>, so that the select region <NUM> forms an arc. The arc may span between approximately <NUM>% to <NUM>% of the total length of the respective wick chamber wall <NUM>, <NUM>. For example, the arc may span approximately <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>% or <NUM>% of the perimeter of the internal <NUM> and/or external <NUM> wick chamber wall. In one form, the select region <NUM> may be located on the internal wall <NUM> of the wick chamber <NUM> and the arc length may span approximately <NUM>% of the length of the internal wall <NUM>, as shown in <FIG>. In this form, the arc of the select region <NUM> forms an angle θ of approximately <NUM>° (<NUM>. 83rad) from the central axis of the cylinder formed by the internal wall <NUM> of the wick chamber <NUM>. It has been found that this configuration helps to disperse gas flow substantially evenly across the interior surface of the cylindrical wick <NUM>.

In another form, it may be possible to increase the flow resistance through the region of the wick chamber internal wall <NUM> located substantially opposite the wick chamber inlet <NUM> by increasing the number of diffusion apertures <NUM> in this target region, while increasing the surface area of the solid portions of the wall <NUM>. In other words, the wall surface area that is taken up by a solid region of the wall <NUM> increases, but the wall <NUM> includes more apertures <NUM> having smaller surface areas. Increasing the wall surface area within the target region results in a reduction in the total surface area of the apertures, thereby increasing the flow resistance of this region. This configuration may decrease the surface area across which gas may pass relative to adjacent areas of the wick chamber internal wall <NUM>, causing gas to disperse across other areas of the wick <NUM>.

In another form, the humidification device <NUM> may comprise a blade diffuser 140a to diffuse gas from the gas inlet <NUM> through the fluid chamber <NUM> and across the wick <NUM>. The blade diffuser 140a may be located in or proximate to the fluid chamber gas inlet <NUM> or wick chamber gas inlet <NUM> so that gas is directed through the blade diffuser 140a and is dispersed before passing across the wick <NUM>. Diffusers may decrease the velocity of gas flow, while increasing the static pressure.

In one form, the diffuser 140a may be shaped similarly to a louvre bladed diffuser, as shown in <FIG>. The diffuser 140a may be of any suitable form, including but not limited to a straight bladed diffuser, linear slot diffuser, swirl diffuser, jet diffuser, barrel diffuser, perforated diffuser, plain face diffuser, louvre bladed diffuser, or any combination of these.

In one form, the humidification device may comprise a diffuser in the form of a grille 140b. The grille 140b may be formed from a plurality of interconnecting grille members <NUM> that may be spaced from each other and connected together at intersecting points in a regular or irregular arrangement. A grille member <NUM> may be oriented substantially vertically, horizontally, or diagonally. A grille member <NUM> may be straight, curved, or angled. A grille member <NUM> may have a substantially uniform or non-uniform shape. For example, a grille member <NUM> may have a substantially curved "S" shape. A grille member <NUM> may have a substantially uniform thickness or a non-uniform thickness, such as being wider at the bottom than the top or vice versa, or wider or thinner at a central region of the grille member <NUM>.

In one form, the diffuser may comprise a substantially regular arrangement of diffusion grille apertures <NUM> interspersed between grille members <NUM> to form a diffusion grille 140b for diffusing gas across the wick <NUM>, as shown in <FIG> and <FIG>. The grille apertures <NUM> may be of any regular or irregular shape, such as quadrilateral, circular, triangular, or amorphous shapes. In a preferred form, the grille apertures <NUM> are rectangular. Any number of grille members <NUM> can be used to increase or decrease the size of the grille apertures <NUM> between the grille members <NUM> and to therefore influence the flow of gas through the inlet <NUM>. At least one of the grille apertures <NUM> may form a gas inlet <NUM> of the wick chamber <NUM>. Optionally, the wick chamber comprises multiple gas inlets and/or gas outlets.

The grille 140b may be of any suitable design to disperse gas flow across the wick <NUM>. For example, the grille 140b may comprise an egg crate grille, bar grille, transfer grille, or any combination of these.

A cylindrical, tubular wick chamber <NUM> having an external wall <NUM> and an internal wall <NUM> may comprise a double layered grille 140b at the wick chamber inlet <NUM>, as shown in <FIG>. For example, the external wall <NUM> may comprise an arrangement of diffusion grille apertures <NUM> within a grille 140b that extends across the wick chamber inlet <NUM>. Similarly, the internal wall <NUM> may comprise an arrangement of diffusion grille apertures <NUM> within a grille 140b that extends across the wick chamber inlet <NUM>. Alternatively, only the external wall <NUM> or the internal wall <NUM> may form a grille 140b across the wick chamber inlet <NUM>. In the embodiment shown in <FIG>, only the internal wall <NUM> forms a grille 140b across the inlet <NUM>.

In yet another form, the humidification device <NUM> may comprise a fibrous diffuser or a diffuser comprising a fabric/textile diffuser 140c that spans a length of the wick chamber inlet <NUM> to disperse gas across the wick <NUM>. In one form, a fabric diffuser 140c is located at the gas inlet <NUM> on the internal wall <NUM> of a cylindrical wick chamber <NUM>. In another form, a fabric diffuser 140c is located at the gas inlet <NUM> on the external wall <NUM> of a cylindrical wick chamber <NUM>. Alternatively, a fabric diffuser 140c may be located at the gas inlet <NUM> at both the internal <NUM> and external walls <NUM> of the wick chamber <NUM>. The fabric used in the diffuser 140c may be any form of material, such as fibrous material. Preferably, the fabric is a woven material.

In one form, the wick <NUM> may be configured to help diffuse gas flow across the wick <NUM>. In this form, the body of the wick <NUM> may have a variable thickness. For example, in a substantially cylindrically shaped tubular wick <NUM> having an internal space or hollow region, as shown in <FIG>, the portion of the wick <NUM> nearest the wick chamber gas inlet <NUM> (the wick inlet portion 131a) has a first thickness ti that may be thinner than the second thickness t<NUM> of the wick portion located substantially opposite the wick chamber inlet <NUM>. Conversely, the first thickness ti of the wick <NUM>, at the wick inlet portion 131a, may be thicker than the second thickness t<NUM> of the opposite wick portion. The side portions of the wick <NUM> may be of a third thickness that may be thinner, of substantially equal thickness, or thicker than the first or second thicknesses of the wick inlet portion 131a and opposing wick portion respectively. In the embodiment shown in <FIG>, the wick inlet portion 131a and side portions are substantially the same thickness whereas the wick portion opposing the gas inlet <NUM> is of a greater thickness. Increasing the thickness of the wick portion opposite the wick chamber inlet <NUM> will increase the impedance of gas flow through that portion of the wick <NUM>. Therefore, gas will tend to disperse across the wick <NUM> more evenly around the inside surface of the tubular wick <NUM>, with a small amount of gas passing across the thick portion of the wick <NUM> and the remaining gas dispersing and passing through the thinner portions of the wick <NUM>.

A wick <NUM> having a wick body comprising at least two spaced apart opposed portions and at least one internal space/hollow region, forming the space between the first and second opposed portions, may also encourage gas to disperse throughout the body of the wick. For example, gas entering the wick may initially flow through a first portion or wall of the wick body before the gas reaches the hollow region. In the hollow region, the gas may spread out to fill the hollow region and may then be pushed through the second portion or other portions/walls of the wick body as more gas enters the hollow region. Furthermore, gas directed through the wick inlet portion 131a can be distributed throughout the internal space prior to passing through the second portion of the wick body. This increases the surface area of the wick <NUM> through with the gas can pass before being directed through the outlet, increasing the humidity output and therefore the effective efficiency of the apparatus.

In one form, the wick may be at least partially disposed between the gas inlet and the gas outlet of the fluid chamber to cause gas that enters the fluid chamber via the gas inlet to pass through or over a first of two spaced apart portions of the wick body, across the space or hollow region between the two body portions, and then through or over the second portion of the wick body before exiting the fluid chamber via the gas outlet.

The gas inlet <NUM> to the fluid chamber <NUM> and/or the wick chamber <NUM> may also be configured to enhance the dispersion of gas across the wick <NUM>.

In one form, the gas inlet <NUM> to the wick chamber <NUM> enters the chamber <NUM> at a transition region at which a curved wall of the gas inlet curves outwardly to form the external wall <NUM> of the wick chamber. In other words, the corner formed at the transition region where the gas inlet meets the external wall of the wick chamber comprises a curved radius 104a, as shown in <FIG>. The curved radius 104a of the gas inlet <NUM> at the transition region encourages gas entering the wick chamber <NUM> to diffuse more evenly through and over the wick by exploiting a Coanda effect. The Coanda effect causes the gas flow to attach to nearby surfaces and to therefore follow the curved radius 104a along the external wall <NUM> of the wick chamber <NUM> so that the gas is dispersed more evenly across the wick <NUM> in the wick chamber <NUM>. The humidification device <NUM> may comprise a curved radius gas inlet to the fluid chamber <NUM>, the wick chamber <NUM>, or both. <FIG> shows a generic curved radius gas inlet <NUM> that may be used in a fluid chamber <NUM>, for example.

In another form, as shown in <FIG>, the fluid chamber inlet <NUM> may be located on the top of the fluid chamber, such as through the fluid chamber lid <NUM>. Gas flow is directed from the fluid chamber inlet <NUM> to the wick chamber <NUM>. The base <NUM> of the wick chamber and therefore the bottom of the wick <NUM> lies beneath the fluid level in the fluid chamber <NUM>. Gas flow entering the fluid chamber <NUM> is dispersed by the fluid <NUM> in the chamber <NUM>, causing the gas to flow more evenly across the exposed surface area of the wick <NUM>, particularly the interior surface of the wall(s) defining the hollow region of the wick <NUM>, where the wick includes a hollow region, such as where the wick is a tubular wick <NUM>.

In another form, the fluid chamber inlet <NUM> may have a substantially frustoconical shape having an enlarged diameter at the fluid reservoir end of the gas inlet <NUM> so that the wall(s) of the gas inlet <NUM> flare outwardly as the gas inlet <NUM> opens into the fluid chamber <NUM>. In this configuration, gas flowing through the inlet <NUM> may be caused to disperse through the chamber <NUM> by the frustoconical shape of the gas inlet <NUM>.

In any form, the gas inlet <NUM> may comprise a diffuser <NUM>, as discussed above, such as a louvre diffuser, grille, fabric diffuser, or any other suitable system for diffusing gas flow through the gas inlet.

Another form of wick humidifier or humidification device <NUM> is shown in <FIG>. Although all forms of wick humidifier shown and disclosed in this specification may be configured to be portable, the humidifier shown in <FIG> may be particularly suitable as a portable humidifier/humidification device. In this form, the humidification device <NUM> comprises a housing <NUM> comprising a wick chamber <NUM> and a fluid chamber <NUM>. The fluid chamber <NUM> is preferably located immediately adjacent to the wick chamber <NUM>, but may be spaced from the wick chamber in alternative embodiments. The wick chamber <NUM> is configured to contain a wick <NUM>. The fluid chamber <NUM> is configured to contain fluid <NUM> that is fed to the wick chamber <NUM> through a fluid flow path <NUM> connecting the fluid chamber <NUM> to the wick chamber <NUM>. The fluid chamber <NUM> and wick chamber <NUM> may each comprise an opening <NUM> to allow a person to access the fluid <NUM> and wick <NUM> respectively. The humidification device <NUM> may also comprise at least one lid. Preferably, the lid comprises or consists of a seal <NUM> configured to cover or seal across the openings of both the fluid chamber <NUM> and wick chamber <NUM>. However, in other forms, the device <NUM> may comprise a first lid to cover or seal across the opening of the fluid chamber <NUM> and a second lid to cover or seal across the opening of the wick chamber.

The wick chamber <NUM> comprises a gas inlet <NUM>, through which gas can enter the chamber and pass across the wick <NUM>, and a gas outlet <NUM> through which humidified gas can exit the wick chamber <NUM> for delivery to a patient. In one form, the gas inlet <NUM> is formed in a front wall of the wick chamber <NUM> and the gas outlet <NUM> is formed in a rear wall of the wick chamber <NUM>. The fluid chamber gas outlet <NUM> may be positioned substantially opposite the wick chamber gas inlet <NUM>.

The wick <NUM> may be substantially planar (two-dimensional) or a solid (three-dimensional) form. In other words, it is not necessary for the wick to comprise a hollow interior.

In one form, the wick chamber <NUM> may comprise one or more guides <NUM> to locate the wick <NUM> at a distance from the gas inlet <NUM> and/or gas outlet <NUM>. For example, as shown in <FIG>, the wick chamber <NUM> may comprise a first guide 171a to space the wick <NUM> at a distance from the gas inlet <NUM>, and a second guide 171b to space the wickv131 at a distance from the gas outlet <NUM>. Optionally, the first guide 171a spaces the wick <NUM> at a distance of approximately <NUM> from the gas inlet <NUM>. The distance between the rear of the wick <NUM> and the gas outlet <NUM> is preferably at least <NUM>.

Spacing the wick <NUM> away from the gas inlet <NUM> produces a plenum in front of the wick <NUM> that helps to equalise pressure at the inlet <NUM> side of the wick <NUM> and to disperse gas more evenly across the wick <NUM>. Spacing the wick <NUM> at an appropriate distance away from the gas outlet <NUM> reduces the risk that the surface tension of the fluid <NUM> may bridge the gap between the wick <NUM> and the wall of the wick chamber <NUM> in which the gas outlet <NUM> is located. This configuration may also reduce the risk that fluid <NUM> from the wick <NUM> will be blown through the gas outlet <NUM> to the patient.

In the embodiment shown in <FIG>, gas from a gas generator <NUM> is blown through the gas inlet <NUM> and across the surface of the wick <NUM> facing the inlet <NUM> (the facing surface). As the gas passes through the moist wick <NUM>, the gas is humidified before exiting the wick chamber <NUM> through the gas outlet <NUM>.

The wick chamber <NUM> is configured to hold at least some fluid <NUM> in which the bottom portion of the wick <NUM> sits, so that the fluid <NUM> moves up through the wick <NUM> under capillary action. In one form, the wick chamber <NUM> comprises one or more surrounding external walls <NUM> and a roof or lid <NUM> that meets with upper edges of the wick chamber walls <NUM>. In one form, one of the walls <NUM> of the wick chamber <NUM> or the lid <NUM> of the wick chamber <NUM> may be removable, or may comprise a closeable access opening through which the wick <NUM> can be inserted and from which the wick may be removed from the wick chamber <NUM>. In another form, the bottom of the wick chamber <NUM> may be removable to form an access opening or may comprise a base attached to the wall(s) <NUM> and having a closeable access opening through which the wick <NUM> can be inserted and removed from the wick chamber <NUM>.

The fluid chamber <NUM> comprises surrounding walls <NUM> and a roof or lid <NUM> that meets with upper edges of the surrounding fluid chamber walls <NUM>. In one form, the lid <NUM> of the fluid chamber <NUM> may be removable or may comprise a closeable access opening to allow access to the fluid chamber <NUM> so that fluid <NUM> can be added to and removed from the fluid chamber. In another form, the bottom of the fluid chamber <NUM> may be removable or may comprise a base with a closeable access opening through which fluid <NUM> can be added to and removed from the fluid chamber <NUM>. In one form, a pump may be used to supply fluid to the fluid chamber <NUM> through an access opening at any suitable location in the fluid chamber <NUM>.

Optionally, one or more walls <NUM> of the fluid chamber <NUM> may comprise one or more fluid level indicators to indicate to a user the optimum maximum and/or minimum fluid level at which the humidification device should operate.

In one configuration, the wick chamber <NUM> and fluid chamber <NUM> are adjacent and share a wall, as shown in <FIG>.

The shared wall 122a may comprise an opening, such as a fluid channel <NUM>, that forms a fluid flow path <NUM> through which fluid <NUM> may flow from the fluid chamber <NUM> to the wick chamber <NUM>. Fluid <NUM> from the fluid chamber <NUM> pools in the bottom of the wick chamber <NUM> to wet the wick <NUM>.

In one form, the humidification device <NUM> comprises a detachable base <NUM> that is configured to seal across an opening at the bottom of both the fluid chamber <NUM> and the wick chamber <NUM>. In this configuration, it is possible to access both the fluid chamber <NUM> and the wick chamber <NUM> by turning the device <NUM> upside down and removing the base <NUM>. The fluid chamber <NUM> may be filled and the wick <NUM> may be replaced before the base <NUM> is attached to bottom edges of the walls of the housing <NUM> (such as the fluid chamber walls <NUM> and wick chamber walls <NUM>) to form a seal that prevents fluid <NUM> from escaping through the base <NUM>. The humidification device <NUM> is then turned to its upright position, ready for use.

In one form, the base <NUM> comprises one or more guides <NUM> to locate the wick at a desired distance from the gas inlet <NUM> and gas outlet <NUM>. For example, the base <NUM> may comprise a first guide 171a for spacing the wick away from the gas inlet <NUM> and a second guide 171b for spacing the wick <NUM> away from the gas outlet <NUM>.

In one form, the base <NUM> may comprise a retaining channel or groove <NUM> at or near its perimeter. The groove <NUM> may be configured to receive bottom edges of the surrounding walls <NUM>, <NUM> of the fluid chamber and wick chamber. In one form, as shown in <FIG>, the bottom edges of the chamber walls <NUM>, <NUM> comprise a rim <NUM> configured to engage with the groove <NUM> of the base <NUM> to form a fluid tight seal.

The base <NUM> may also comprise a partition channel or groove <NUM> that extends across the base. The partition groove <NUM> is positioned to at least partially receive the bottom edge of the shared wall 122a of the fluid chamber <NUM> and wick chamber <NUM>.

In one form, as shown in <FIG>, the partition groove <NUM> comprises an opening, such as a fluid channel <NUM>, that forms a fluid flow path <NUM> between the fluid chamber <NUM> and the wick chamber <NUM>. In this configuration, fluid <NUM> from the fluid chamber <NUM> may be fed through the fluid channel <NUM> to the wick chamber <NUM> where the fluid <NUM> pools at the base of the wick chamber <NUM> and wets the wick <NUM> sitting on the base of the wick chamber <NUM>.

In one form, both the shared wall <NUM> of the fluid and wick chambers <NUM>, <NUM> and the partition groove <NUM> of the base <NUM> comprise a fluid channel forming a fluid flow path <NUM>. In this form, the base <NUM> is attached to the humidification device housing <NUM> so that the fluid channel <NUM> of the base substantially aligns with the fluid channel <NUM> of the shared wall <NUM> of the housing <NUM> to allow fluid to flow from the fluid chamber <NUM> to the wick chamber <NUM>.

<FIG> and <FIG> show one form of humidification device <NUM> comprising adjacent wick and fluid chambers <NUM>, <NUM> and in which the fluid chamber <NUM> contains water. The wick chamber <NUM> has a first volume that is dimensioned to contain a wick <NUM>. In the illustrated embodiment, the volume of the wick chamber <NUM> is <NUM><NUM>. The fluid chamber <NUM> has a second volume that is dimensioned to hold a sufficient volume of fluid <NUM> to humidify gas for at least one full night (for about <NUM> to <NUM> hours). In the illustrated embodiment, the volume of the fluid chamber <NUM> is <NUM><NUM>. In this configuration therefore, the fluid chamber <NUM> has a larger volume than the wick chamber <NUM>. One possible ratio between the volume of the wick chamber <NUM> and the fluid chamber <NUM> is <NUM>:<NUM> or <NUM>:<NUM>. However, other ratios may also be suitable.

In use, fluid from the fluid chamber <NUM> will flow to the wick chamber <NUM> through the fluid flow path <NUM> until a point of equilibrium is met. This point of equilibrium is typically met when the level of fluid <NUM> in the wick chamber <NUM> lies just above the height of the fluid channel <NUM>, <NUM>. This is the maximum fluid level of the wick chamber <NUM>. Therefore, the fluid level in the wick chamber <NUM> is typically less than the fluid level in the fluid chamber <NUM>.

The fluid <NUM> in the wick chamber <NUM> soaks into the bottom of the wick <NUM> and moves up the wick <NUM> under capillary action to dampen the wick <NUM>. The fluid level in the wick chamber <NUM> lowers below the maximum height of the fluid channel <NUM>, <NUM> as fluid is soaked up by the wick <NUM>. Gas from the wick chamber <NUM> may then pass through the fluid channel <NUM>, <NUM> and into the fluid chamber <NUM> to displace the fluid <NUM> that has left the fluid chamber <NUM>. Gas flowing across the wick <NUM> is humidified by the wick <NUM>. As the wick <NUM> humidifies gas, the wick <NUM> soaks up more fluid to replace the fluid that humidified the gas. Therefore, fluid continues to flow from the fluid chamber <NUM> to the wick chamber <NUM> until the point of equilibrium is reached again. Therefore, the wick <NUM> is able to hold fluid in the wick chamber <NUM> but the wick chamber is prevented from flooding.

One advantage of maintaining a substantially constant fluid level in the wick chamber is that a substantially constant surface area of the wick is available for gas <NUM> to pass across. This provides improved control of the humidification output of the humidification device. Contrast this with other wick humidifiers where the exposed surface area of the wick increases over the course of the therapy session as more fluid is evaporated and transferred to the gas passing across the wick.

Another advantage of maintaining a substantially constant fluid level in the wick chamber is that it allows for a substantially known volume of wick material to be used.

Furthermore, by providing a low level of fluid in the wick chamber, the overall volume of the humidification device may be minimised and the device may be more tolerant to being tilted at an angle, such as during transportation, without fluid flowing out the inlet or the outlet.

The humidification device <NUM> may be configured to further improve the dispersion of gas passing across the wick by increasing the gas inlet opening <NUM> to the wick chamber <NUM> relative to the facing surface of the wick <NUM>.

The gas inlet <NUM> may have an opening in a wall <NUM> of the wick chamber <NUM>. The gas inlet opening <NUM> has an inlet surface area (ISA). Where the gas inlet <NUM> is cylindrical and the inlet opening is circular, the ISA is the surface area of a circle formed with a centre at the cylindrical axis of the gas inlet <NUM>. The facing surface of the wick <NUM> also has a surface area (WSA), which is the surface area of a plane on the front of the wick, facing the gas inlet <NUM>. Increased dispersion of gas flow across the wick <NUM> can be achieved by increasing the ratio of the ISA to the WSA. For example, maximum dispersion can be achieved with ISA:WSA of <NUM>:<NUM>. The configuration shown in <FIG> and <FIG> has an ISA:WSA ratio of approximately <NUM>:<NUM> or approximately <NUM>:<NUM>. In other embodiments, this ratio may differ. For example, the ISA: WSA ratio could be <NUM>:<NUM>.

<FIG> show another form of humidification device <NUM> configured to disperse gas flow substantially evenly across a wick <NUM> by controlling gas flow within the device <NUM> or system <NUM> using a control system or controller. In one form, the control system/controller comprises one or more control valves to control gas flow within the humidification device <NUM> or system <NUM>. This embodiment operates in substantially the same manner as that illustrated in <FIG>, but is configured differently. In the humidification device <NUM> shown in <FIG>, a bypass channel <NUM> is provided so that a portion of gas flow can be directed across the wick <NUM> and a portion of gas flow can be directed to bypass the wick <NUM> and instead flow along the bypass channel <NUM> before the gas portions then meet together and are delivered to a patient. This configuration allows the gas flow path to be controlled in order to control the humidity of gas delivered to a patient. Any of the embodiments shown in <FIG> may also be configured to comprise a bypass channel <NUM>.

In one form, as shown in <FIG>, a humidification device <NUM> or system <NUM> comprises a flow generator <NUM> having a gas inlet <NUM> and a gas outlet <NUM>, a control system or controller, to control gas flow, comprising at least one control valve <NUM>, a first gas channel <NUM>, and a second gas channel <NUM>. The control system with valves may be used in the humidification devices of <FIG> and <FIG>. The first gas channel <NUM> may be configured to direct gas to a humidification module <NUM> and the second gas channel <NUM> may be a bypass channel to allow gas to bypass the humidification module <NUM>. The control valve <NUM> may be configured to direct an amount of gas through the first channel <NUM>, the second channel <NUM> or both. In one form, the control valve <NUM> may be configured to direct between <NUM>% to <NUM>% of gas to the first channel <NUM> or the second channel <NUM>. For example, the control valve <NUM> may direct <NUM>% of gas along the first channel <NUM> and <NUM>% of gas along the second channel <NUM>. In another example, the control valve <NUM> may direct <NUM>% of gas along the first channel <NUM> and <NUM>% of gas along the second channel <NUM>.

In one form, the humidification device <NUM> or system <NUM> may comprise a variable diffuser located at the inlet of the first/humidification flow path/channel <NUM> that flows through the humidification module <NUM>. The variable diffuser may act as both a valve and a diffuser. For example, the variable diffuser may be comprise multiple apertures, any one or more of which may be configured to be fully open, partially open, or closed. When in a first position, the variable diffuser can be in an open position, allowing air flow through the holes, acting simultaneously as a diffuser. When the variable diffuser is in a closed position, the diffuser may block gas flow through the humidification flow path. By using a variable diffuser as a valve, it may be possible to remove the need for a diffuser downstream. The variable diffuser arrangement may be similar to a salt shaker or the like having an upper surface comprising multiple apertures within a localised region, and a lower surface, located proximate to the upper surface but being only half the size of the upper surface and therefore covering only half of the upper surface. The upper surface may be rotated relative to the lower surface so that the lower surface: (a) covers one or more apertures to close those apertures; (b) partially covers one or more apertures so that these apertures are partially open; and/or does not cover one or more apertures so that these apertures are fully open.

The control valve <NUM> may be positioned at any suitable location within the humidification device <NUM>.

<FIG> shows a simplified schematic representation of a humidification system <NUM> comprising a flow generator <NUM>, a first gas channel <NUM>, a second gas channel <NUM>, and a humidification device or humidifier <NUM>. <FIG> also illustrates several different locations in which one or more control valves <NUM> may be positioned to control gas flow through the first gas channel <NUM> and second gas channel <NUM>. For example, a control valve <NUM> may be located at any of the positions A, B, C, D, or E depicted in <FIG>.

A control valve <NUM> positioned at location A (which is the intersection between a gas outlet from the flow generator <NUM>, the first gas channel <NUM> and the second gas channel <NUM>), can be configured to direct between <NUM>% to <NUM>% of gas flow through the first channel <NUM> and through the second channel <NUM>, or through a controlled combination of both channels <NUM>, <NUM>.

Similarly, a control valve <NUM> positioned at location B, where the first and second channels <NUM>, <NUM> meet again at a gas outlet <NUM>, may be configured to allow only gas from the first channel to pass through the valve <NUM> and out the gas outlet <NUM>, or to allow only gas from the second channel to pass through the valve <NUM> and out the gas outlet <NUM>, or to allow gas from both the first and second channels <NUM>, <NUM> to pass through the valve <NUM> and out the gas outlet <NUM>.

In another embodiment, a first control valve <NUM> may be positioned at location C in the first flow channel <NUM>, prior to the humidifier, and a second control valve <NUM> may be positioned at location D in the second flow channel <NUM>. Each of the control valves <NUM> at locations C and D may be fully open to allow gas <NUM> to flow freely through the valve <NUM>, fully closed to prevent gas <NUM> from flowing through the valve <NUM>, or partially open to restrict the amount of gas <NUM> passing through the valve <NUM>. Valves <NUM> at locations C and D may be configured to open, close or partially open in order to direct <NUM>% of gas <NUM> through the first channel <NUM> and through the humidifier, <NUM>% of gas through the second channel <NUM> to bypass the humidifier, or to allow a portion of the total amount of gas <NUM> to pass through the first channel <NUM> and the remaining portion of gas <NUM> to pass through the second channel <NUM>. In other words, valves C and D may be configured to control the amount of gas <NUM> flowing through the first and second channels <NUM>, <NUM>. The amount of gas <NUM> flowing through any one of the channels <NUM>, <NUM> may be between <NUM>% and <NUM>% of the gas flow <NUM> produced by the flow generator <NUM>. For example, the proportion of gas flow <NUM> between the first and second channels <NUM>, <NUM> may be: (<NUM>%:<NUM>%); (<NUM>%: <NUM>%); (<NUM>%:<NUM>%); (<NUM>%: <NUM>%); (<NUM>%:<NUM>%); (<NUM>%:<NUM>%); (<NUM>%:<NUM>%); (<NUM>%: <NUM>%); (<NUM>%:<NUM>%); (<NUM>%: <NUM>%); (<NUM>%: <NUM>%).

In another form, instead of positioning a valve <NUM> prior to the humidifier at location C, a valve <NUM> may be positioned in the first channel <NUM> and after the humidifier at location E. In this location, the valve <NUM> would have similar effect to a valve <NUM> at location C.

The control valve <NUM> may be any suitable form of valve for controlling gas flow <NUM> through the humidification device <NUM>. For example, the control valve may comprise a ball valve, gate valve, globe valve, butterfly valve, needle valve, or the like. In one form, as shown in <FIG>, the control valve <NUM> is a ball valve. The ball valve <NUM> may be rotated on its axis to direct gas flow to the first channel <NUM> or the second channel <NUM> or to direct an amount of gas <NUM> along each of the first and second gas channels <NUM>, <NUM>. <FIG> show how the ball valve <NUM> can direct gas <NUM> along both gas channels <NUM>, <NUM> and can then be rotated to direct gas along the first gas channel <NUM> only. Similarly, <FIG> show how the ball valve <NUM> can direct gas along both gas channels <NUM>, <NUM> and can then be rotated to direct gas <NUM> along the second gas channel <NUM> only. <FIG> show how a ball valve <NUM> can be oriented to direct gas flow along both the first and second gas channels <NUM>, <NUM>. The valves <NUM> shown in <FIG> are positioned at the control valve location shown in the humidification device <NUM> of <FIG>.

The ball valve <NUM> may be manually, pneumatically or electrically actuated. If the ball valve is manually activated, it may be beneficial for the humidification device to include a position indicator, such as a gauge or scale that provides a user with an indication of the valve position (i.e. whether the valve is open, closed or partially open to the first channel and whether the valve is open, closed, or partially open to the second channel).

In another embodiment, the control system may comprise at least one control valve <NUM> in the form of a gate valve, which may be fully open to allow gas to flow freely along a gas channel, closed to prevent gas flow along a gas channel, or partially open to restrict gas flow along a gas channel. For example, in one form, as shown in <FIG>, the control system comprises a first gate valve 170a, in or at the entrance to a first gas channel <NUM>, and a second gate valve 170b in or at the entrance to a second gas channel <NUM>. In this configuration, if <NUM>% of gas from the gas generator <NUM> is to flow along the first gas channel <NUM> to be humidified, the first gate valve 170a is fully opened and the second gate valve 170b is closed. Conversely, if <NUM>% of gas is to flow along the second gas channel <NUM> to bypass the humidification process, the second gate valve 170b is fully opened and the first gate valve 170a is closed. If the gas flow is to be split between the first and second gas channels <NUM>, <NUM>, both first and second gate valves 170a, 170b may be partially open. Again, the gate valves <NUM> may be manually or electronically actuated.

In another form, as shown in <FIG>, gas flow is controlled by a single gate valve <NUM> that is moveable between a first position, in which the first gas channel <NUM> is open, and a second position, in which the second gas channel <NUM> is open. This movement is indicated by the dashed line in <FIG>. In this configuration, a single control valve <NUM> may control and divide gas flow <NUM> between the two gas channels <NUM>, <NUM>, as opposed to needing two control valves. Again, the control valve may be electronically, pneumatically or manually actuated.

<FIG> illustrate one form of gate valve <NUM> that may be used to open, close, or partially open access to a gas channel. When the gate of the gate valve <NUM> is lowered across a gas channel, as shown in <FIG>, the valve <NUM> is closed and access to the gas channel is blocked. When the gate is fully raised, as shown in <FIG>, access to the gas channel is open and unimpeded.

<FIG> shows another form of control valve <NUM> that may be used with the humidification device <NUM> or system <NUM>. In this form, the control valve acts in a similar manner to the gate valve, but is formed of a flexible material that is able to:.

In another form, the humidification device <NUM> or system <NUM> may comprise two flow generators <NUM>. For example, the device <NUM> may comprise a first flow generator 110a to generate a first gas flow that is directed along a first flow path/channel <NUM> across the wick <NUM> of a wick humidifier, and a second flow generator 110b to generate a second gas flow that is directed along a second flow path/channel <NUM> that bypasses the humidifier. The first and second gas flows combine downstream, mixing together to form a single unified flow path <NUM>. Optionally, the outlet of one or both flow generators may comprise a check valve to prevent backflow of air from the other flow generator.

The amount of gas <NUM> directed by each flow generator <NUM> may be tailored to control the humidity of the gas <NUM> delivered to a patient. For example, if half the maximum humidity of the wick humidifier is desired, the first flow generator 110a and the second flow generator 110b can deliver an equal amount of breathing gas to the unified flow path <NUM>, so that half the gas <NUM> is humidified by the wick <NUM> and half is at ambient humidity.

In one form, a humidification device <NUM> or system <NUM> with dual gas channels/circuits <NUM>, <NUM>, as described above, may comprise a humidification module <NUM> that is modular in nature and may be configured to detachably attach to a flow generator <NUM>. In this configuration, a patient may use the flow generator <NUM> alone, without the humidification module <NUM>, as shown in <FIG>. For example, the bypass channel <NUM> may become the primary gas channel or flow path. When humidified gas is desired, a humidification module <NUM> may be attached to the flow generator <NUM> and at least a portion of the gas generated by the flow generator <NUM> is directed through the module <NUM>. In one form, the humidification device <NUM> of <FIG> and/or a humidification device as described above may form the humidification module <NUM> and be attached to the flow generator <NUM>. Control valve(s) <NUM> may be operated to direct gas flow through the first gas channel <NUM> and/or second/bypass gas channel <NUM>, as described above.

In one form, as shown in <FIG>, a humidification device <NUM> and system <NUM> comprising a flow generator <NUM>, having a gas inlet <NUM> and a gas outlet <NUM>, and a detachably attachable humidification module <NUM> may comprise a control system comprising a trap door arrangement <NUM> to control gas flow within the device <NUM>. In this form, the flow generator <NUM> may comprise at least one trap door that may be biased toward a first, closed position when the humidification module <NUM> is not attached to the flow generator <NUM>. The humidification module <NUM> may be attached to the flow generator <NUM> using any suitable attachment system, such as using an interference or snap fit arrangement. The humidification device <NUM> may be configured so that the motion of attaching the humidification module <NUM> to the flow generator <NUM> may cause the trap door(s) <NUM> to move to an open position. For example, the humidification module <NUM> may comprise a protruding gas inlet <NUM> and a protruding gas outlet <NUM> that each press against one of a pair of trap doors <NUM> in the flow generator <NUM> when the humidification module <NUM> is attached to the flow generator <NUM>. The pressure against each trap door <NUM> causes the trap doors to rotate about a respective hinge to a second, open position. In the open position, the trap doors block access to the second bypass gas channel <NUM> so that <NUM>% of gas is directed through the humidification module <NUM>. Conversely, when the humidification module <NUM> is detached from the flow generator <NUM>, the trap doors <NUM> return to the closed position, allowing the gas to flow through the bypass channel <NUM>. In one form, the trap doors <NUM> may comprise an attachment system comprising a latch mechanism to attach the humidification module <NUM> to the flow generator <NUM>.

The trap door(s) <NUM> may be made of any suitable material or combination of materials, such as silicone, or thermoplastic, for example. In one form, the trap door(s) may be made of an overmoulded plastic part. A thermoplastic elastomer or silicone may provide the trap door(s) with characteristics that allow the trap door(s) to hinge from an initial position to a second position and to spring back to the initial position.

<FIG> shows another form of humidification system comprising a modular flow generator <NUM> and humidification module <NUM> having a control system comprising a sliding door arrangement to control gas flow within the system. In this form, the flow generator <NUM> comprises a pair of sliding doors 178a and 178b. In a first position, the sliding doors <NUM> allow gas from the flow generator <NUM> to flow along a bypass gas channel <NUM> within the flow generator <NUM> to provide gas at ambient humidity to a patient. For example, in the first position, the sliding doors <NUM> may be pushed toward the outer edges or corners of the flow generator <NUM> to be out of the way and to block the inlet <NUM> and outlet <NUM> ports of the flow generator that are configured to receive the gas inlet <NUM> and gas outlet <NUM> of the humidification module <NUM>. The humidification module <NUM> may be detachably attached to the flow generator <NUM> by sliding the doors <NUM> away from the inlet and outlet ports <NUM>, <NUM> to a second position, inserting the gas inlet <NUM> of the humidification module <NUM> into the inlet port <NUM> and inserting the gas outlet <NUM> of the humidification module <NUM> into the outlet port <NUM>. In the second position, the sliding doors <NUM> may be pushed together so that the inlet and outlet ports <NUM>, <NUM> are no longer blocked and gas <NUM> from the flow generator <NUM> is caused to pass through a first gas channel <NUM> in the humidification module <NUM> to humidify the gas <NUM>. At least one sliding door <NUM> may be configured to block the bypass channel <NUM>. For example, the first sliding door 178a may comprise an L shape with one leg of the L configured to slide along one wall of the flow generator <NUM> and the other leg of the L configured to block the bypass channel <NUM> when the door 178a is in the second position.

In yet another form, as shown in <FIG>, the flow generator <NUM> may comprise a hinged door <NUM> that closes to cover the inlet and outlet ports <NUM>, <NUM> (as shown in <FIG>) and that hinges open (as shown in <FIG> and <FIG>) to allow the gas inlet <NUM> of a humidification module <NUM> to engage with the inlet port <NUM> and the gas outlet <NUM> of the humidification module <NUM> to engage with the outlet port <NUM> when the humidification module <NUM> is detachably attached to the flow generator <NUM> (as shown in <FIG>). The humidification module <NUM> may comprise a recess <NUM> to receive a portion of the hinged door <NUM>. In one form, the recess <NUM> is located on the underside of the humidification module <NUM> housing, as shown in <FIG>. The hinged door <NUM> may be configured to seal against the body of the flow generator <NUM> when closed. The hinged door <NUM> may be biased to the closed position or may be held in the closed position using a latch or some other suitable closure system. In the closed position, gas <NUM> is caused to flow along the bypass channel <NUM> of the flow generator <NUM>. In the open position, gas <NUM> may flow through the humidification module <NUM>. A control system, using control valves <NUM> or the like, as described above, may be used to control the flow of gas <NUM> through the first gas channel <NUM> in the humidification module <NUM> and the second, bypass channel <NUM> in the flow generator <NUM> so that gas can pass through the first channel <NUM>, the second channel <NUM>, or both channels.

In one form, the humidification module may be configured for retrofit insertion into a humidification device. In this form, the humidification module may comprise a wick chamber within which a wick may be held, as described above. The humidification module may also comprise at least one attachment member to detachably attach the humidification module to a flow generator of the humidification device.

In one form, the humidification system <NUM> may comprise a kit comprising a flow generator <NUM> in fluid connection with a non-humidified gas flow path/circuit to deliver non-humidified gas to a patient; a humidification module/humidifier <NUM> detachably attachable to the flow generator <NUM> and comprising a humidified gas flow path/circuit <NUM> to deliver humidified gas to a patient; and a control system to control the amount of gas that flows from the flow generator <NUM> through the humidified gas circuit <NUM> and the amount of gas that flows from the flow generator <NUM> through the non-humidified gas circuit <NUM>.

The kit may also include a wick <NUM> for use with a wick humidifier <NUM> of the humidification module <NUM>.

Many different forms of wick <NUM> may be used with the humidification devices/humidifiers <NUM> and humidification modules <NUM> described above. However, it is beneficial for the wick to be made from a material having one or more of the following properties:.

Gas is required to be blown through or over the wick so that it can increase in humidity.

Wicking is dependent on capillary action and occurs when the Adhesion Forces between the molecules of a fluid and the wick surface surpass the Cohesion Forces between the fluid molecules. In wicks formed from hydrophilic materials, water/fluid is attracted to the surface of the wick, and therefore spreads out over the wicking elements when in contact with the wick. This phenomenon allows the wick to draw fluid upwards against gravity.

A high effective surface area increases the volume of fluid that can be exposed to gas directed across the wick and consequently increases the efficiency of the humidification device by increasing the humidity of gas after passing across the wick.

It is beneficial for the wicking material to be minimally absorbent. If the material is highly absorbent, static fluid may accumulate in the core of the material, which will detrimentally provide conditions for accelerated bacterial growth.

A wick having anti-microbial and anti-fungal properties can reduce the frequency at which the wick needs to be cleaned and/or replaced. A wick may be provided with anti-microbial and anti-fungal properties in a number of ways known in the industry, such as by using anti-microbial layers or inserts into the wick or the fluid chamber.

Additionally or alternatively, the fluid itself may be treated prior to entering the reservoir, for example by an ultra-violet light emitting diode (LED).

Chemicals that inhibit bacteria growth may be used.

In one form, the wick may be disposable and replaceable or cleanable and re-usable. For example, the wick may be:.

The wick chamber and the contained wick may be removable from the fluid chamber. In one form the wick chamber and/or wick may also be consumable. This allows for individual cleaning and/or replacement of the wick as required by the user. In another form, the entire fluid chamber may be consumable and replaceable.

The wick may also be easy to remove from the wick chamber and may be a consumable component (replaceable and/or cleanable). Certain materials that can be used in the wick, over longer periods of time can have a build-up of bacteria or impurities from the fluid used for humidification (hard water). It can therefore be beneficial to be able to clean the wick, and eventually replace the wick as necessary.

One way of increasing the longevity of the wick is to ensure that it is cleanable. In one form, the humidification device may come with instructions to clean the wick according to a set schedule, such as to clean the wick every two weeks or every <NUM> days. In another form, some manner of adaptive cleaning schedule could be provided for the user. The adaptive cleaning schedule may include providing an indication of the cleanliness of the wick. For example, the humidification device may comprise a guide to indicate to a user when to clean the wick. This can be done in a number of ways, for instance through the use of visual bacteria sensor/s, electronic bacteria sensors or other means.

In one form, the wick humidifier may comprise one or more physical sensors that are configured to detect the presence of bacteria in the apparatus and to provide a visual indication of the presence of bacteria and/or the type of bacteria and/or the extent of bacterial growth on the sensor(s).

In one form, a physical sensor may comprise an item, such as a substrate, that is configured to provide a visual indication of bacteria growing on the item. For example, the item may comprise a flexible plastic layer and a nutrient containing filter paper attached to the plastic layer. The physical sensor may be configured to show coloured spots, such as red spots, when aerobic bacteria forms on the sensor. The number of spots, together with the extent of background colouring/reddening can be used to quantitatively measure microbial growth on the sensor.

In one form, a chemical may be added to the sensor to provide a visual colour indication of bacterial growth.

In one form, a reactant may be impregnated into a material, such as filter paper, where the reactant is configured to cause a colour change in the filter paper when bacteria grow on the paper. For example, a Bradford assay may be used as the visual indication of bacterial growth. In this form, a material may be impregnated with a dye, such as Coomassie Brilliant Blue G-<NUM> for example. When certain acidic conditions are met, due to the growth of bacteria, the sensor may change from red to blue as the dye binds to the protein being assayed.

In another form, a coating may be provided on one or both sides of the sensor and is configured to allow bacteria to grow on the coating.

If the wick comprises a suitable substrate, the physical sensor(s) may be located on the wick, or may be portions of the wick itself. For instance a portion of the wick may be impregnated with the previously described reactant, forming an integral bacteria sensor within the wick.

Alternately, the physical bacteria sensor(s) may be located within the water reservoir as opposed to being directly connected to the wick. This can be beneficial as the physical bacteria sensor/s can be replaced independently of the wick being cleaned. For example, after the user cleans the wick, the physical sensor can be replaced from the water reservoir.

In another form, the wick humidifier may comprise one or more electronic sensors in communication with a control system that are configured to detect the presence of bacteria in the apparatus. The electronic sensor(s) can be located on the wick support structure, or an interior surface of the water reservoir, and can be calibrated in such a way as to be useful to provide a measure of the bacteria present on the wick. For instance, even though the sensor is not located on the wick, or directly exposed to the bacteria on the wick, a correlation can be determined between a bacteria reading measured by the electronic sensor and the bacteria level within the wick, and this correlation can be used to provide a useful indication to the user when the bacteria level within the wick is elevated.

In some forms, the electronic sensor may be configured to alternatively or additionally detect the type of bacteria and/or the extent of bacterial growth on or near the sensor. For the sake of simplicity, preferred forms of sensor (both electronic and physical sensors) will be described herein as being configured to detect the presence of bacteria on or near the sensor, but it should be appreciated that this may alternatively or additionally include detecting the type of bacteria and or the extent of bacteria growth on or near the sensor.

In one form, the electronic sensor may be configured to provide a signal to the electronic control system that indicates whether bacteria has or has not been detected. For example, the electronic sensor may be configured to provide the control system with a signal when the presence of bacteria is detected, or when a certain type of bacteria is detected, or when a certain predetermined threshold level of bacterial population is detected. Alternatively, the control system may be configured to identify when a predetermined threshold level of bacteria has been detected by the sensor, such as after the sensor has generated a predetermined number of signals.

Upon receiving a signal from a bacteria sensor, or from a predetermined number of bacteria sensors, or upon receiving a predetermined number of signals from a bacteria sensor or from two or more bacteria sensors, the control system may be caused to change from a normal operating mode to an alert mode. The control system may be configured so that, in the alert mode, the system provides an indication/alert to a user interface that indicates to the user that the apparatus or a component of the apparatus needs to be cleaned as a result of bacterial growth. The alert may be any suitable form of indication to a user, including but not limited to a visual display (such as one or more lights, images, words, text message, email, colour changes, or symbols for example), and/or a sound indication (such as one or more beeps for example). Where the user interface is a remote user interface, such as a computer or a smartphone, for example, the control system may be configured to transmit the alert (in the form of an alert signal) to the user interface, which may then present the alert on a screen in any suitable form of visual indication, such as an image, words, symbols, colour changes, lights, for example. Alternatively, or additionally the remote user interface may be configured to present an audio alert, in the form of a noise, which may be of any suitable form, including beeps or other sounds.

In another form, the electronic bacteria sensor may be configured to generate an indication of bacteria detection, which may be a visual or audio indication. Optionally, electronic sensors that are configured to generate a visual alert may be located in areas of the apparatus that are easily visible to a user, such as in the interfacing structure. Additionally or alternatively, physical sensors configured to provide a visual indication of bacterial growth may be located in areas of the apparatus that are easily visible to a user.

An electronic bacteria sensor employed by a breathing treatment apparatus may be configured to operate continuously (in a continuous mode) or at fixed time intervals (in a periodic mode) to sense the presence of bacteria within the breathing treatment apparatus. Preferably, the control system comprises a clock and is configured to connect to the sensor to determine the mode of operation of the sensor.

In one form, the electronic sensor(s) may comprise a filter to filter out particles that are over a predetermined size.

In one form, an electronic bacteria sensor that may be used with the apparatus may comprise an electrochemical biosensor. This form of sensor may be configured to measure electrical impedance as a method of detecting bacteria in contact with the sensor. For example, the electronic bacteria sensor may comprise a sensing surface comprising a bio-recognition element and may be configured to produce a signal if the sensor identifies changes in electrical properties of the sensing surface, such as changes in impedance, capacitance, or resistance for example. These changes may occur as a result of interactions between the bio-recognition element on the sensor's sensing surface and bacteria to which the sensor is exposed.

An electronic bacteria sensor may be located at any suitable area of the apparatus. For example, an electronic bacteria sensor may be located inside the humidification compartment, such as above or below the water line of the water reservoir. If the sensor is located below the water line, the sensor may be configured to detect the presence of bacteria in the water contacting the sensing surface. If the sensor is located above the water line, the sensor may be configured to detect bacteria in condensation formed on the sensing surface as a result of elevated humidity levels within the humidification compartment during use.

Upon detection that the wick has an elevated bacteria level, the user may proceed to clean the wick in one of a number of ways.

In some embodiments, the wick is disposable, and can simply be removed from the wick chamber, disposed of, and replaced with a new wick.

In some embodiments, the wick can be cleaned by running an appropriate cleaning solution through the wick. In some embodiments, this may be hot water or a water/vinegar solution.

In some embodiments, the wick may be left to dry out for a predetermined period of time to sterilize. Alternately, the flow generator may pass air through or over the wick after the fluid supply in the fluid chamber and wick chamber is emptied to actively dry the wick.

In some embodiments, the humidification device may include a sterilization system. The sterilization system may be automatically activated on detection of a high bacteria level, and/or it may be manually activated by the user.

In one form, the sterilisation system comprises a series of ultra-violet lights, such as ultra-violet LED lights. The lights may be strategically located at any suitable location in the humidification device to sterilise the wick, such as in the interior of the fluid chamber or wick chamber. When the control system receives a signal from one or more sensors that causes the control system to identify the presence of bacteria, or to identify the presence of a certain type of bacteria, or to identify that a predetermined threshold of bacteria levels have been met, the control system may generate an alert and/or the control system may activate the sterilisation system.

Claim 1:
A humidification device (<NUM>) for use in CPAP, wherein the device comprises: a wick (<NUM>),a wick chamber (<NUM>) supporting the wick (<NUM>); a gas inlet (<NUM>) to the wick chamber (<NUM>); and a diffusion system for directing or controlling gas flow through the device, characterised in that the diffusion system comprises a diffuser (<NUM>, 140a, 140c) located at or in the gas inlet (<NUM>), to diffuse gas flowing from the gas inlet (<NUM>) and into the wick chamber (<NUM>) substantially evenly through or over the wick (<NUM>), and wherein the wick chamber (<NUM>) comprises a foraminous structure for supporting the wick (<NUM>) within the wick chamber (<NUM>) and diffusing gas flow through or over the wick (<NUM>).