Patent Description:
It is known to provide in a wall of an ostomy appliance ('bag' or 'pouch' as they are commonly known in the art) an aperture to permit waste gases to escape from a waste collecting chamber of the ostomy appliance. This is necessary to prevent the bag expanding too much with gas and potentially from leaking or bursting whilst filled with waste. In some prior art ostomy appliances the aperture is covered by a filter, the purpose of which is to de-odorise the waste gases before they exit to atmosphere. In the known ostomy appliances the aperture and filter are usually positioned in an upper part of the bag above a stoma receiving opening. Such filters are usually, but not always, positioned inside the exterior wall of ostomy appliance so that waste gas must pass through the filter before exiting the bag via the aperture.

<CIT> discloses an ostomy bag vent including a filter including a media layer exposed to an interior of an ostomy bag.

<CIT> which may be seen as the closest prior art document, discloses a drainable ostomy pouch comprises two proximal and distal flexible stiffening strips of stiff material extending immediately adjacent to and along drainage opening and attached by heat sealing or adhesion to outer surface of drainage portion
Although intermediate walls are often provided in between the exterior walls in order to create a tortuous path for waste gas to travel through in order to get to the filter, thus making it difficult for bodily waste to come into contact with the filter, these walls are quite often unsuccessful in keeping bodily waste away from the filter. In this case, the filter can become blocked during use which causes the appliance to gradually inflate with waste gases with no means of escaping, causing discomfort and/or embarrassment to the user.

The present invention looks to address this problem.

In a first aspect, the present invention relates to an ostomy appliance according to claim <NUM>.

Further features of the first aspect of the invention are set out in claims <NUM> to <NUM> appended hereto.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, of which:-.

Referring firstly to <FIG> these show a first embodiment of an ostomy appliance in accordance with the present invention, shown generally at <NUM>. The general construction of the ostomy appliance <NUM> is similar to those well known in the art and in that sense it includes first <NUM> and second <NUM> walls which are connected to each other at or near their peripheries, for example by welding or using an adhesive. The ostomy appliance <NUM> shown could be a drainable appliance, meaning that its contents could be emptied through an outlet (<NUM>, shown in broken lines) between the first <NUM> and second <NUM> walls.

The first wall <NUM> has a stoma-receiving opening <NUM> and is connected to a generally circular connection member <NUM> in the form of a flange for adhering the appliance <NUM> to a user around their stoma. The connection member <NUM> could be any appropriate shape, however.

The ostomy appliance <NUM> defines at least one chamber therein. A waste collecting chamber <NUM> is provided which communicates with the stoma-receiving opening <NUM> and, if the ostomy appliance is a drainable appliance, at its lower end with an outlet (<NUM>). The waste collecting chamber <NUM> is defined between the first <NUM> and second <NUM> walls and is provided as the primary chamber for collecting a user's waste, which enters the chamber through the opening <NUM> in the first wall <NUM>. More chambers (not shown) may be provided within the ostomy appliance, for example in order to create a tortuous path for the waste gas to exit the appliance and/or to allow fluid in a further chamber to pass into the waste collecting chamber <NUM> via a non-return valve.

An aperture <NUM> is provided in the second wall <NUM> to permit waste gas within the ostomy appliance <NUM> to exit the appliance. The aperture <NUM> is preferably in use provided above the stoma-receiving opening <NUM> to reduce the likelihood of waste collected in the waste collecting chamber <NUM> from getting near to the aperture <NUM>. The aperture <NUM> is preferably circular in shape but can be formed in a number of different shapes. The aperture <NUM> could in some embodiments of the present invention include a plurality of apertures in the form of perforations provided in the second wall <NUM>. Although the aperture <NUM> is shown in <FIG> as being provided in the second wall <NUM>, it may instead be provided in the first wall <NUM>. Alternatively, apertures may be provided on both the first <NUM> and second <NUM> walls.

A filter <NUM> is provided externally of the ostomy appliance <NUM> as shown in <FIG> and <FIG>. More specifically the filter <NUM> is attached to an exterior surface of the second wall <NUM>. The filter <NUM> is attached to the second wall <NUM> adjacent the aperture <NUM> so that the aperture is fully covered by the filter <NUM>. It can be seen on <FIG> that the aperture <NUM> is a smaller diameter than the diameter of the filter <NUM>. Therefore, any waste gases that exit the ostomy appliance <NUM> through the aperture <NUM> must pass through the filter <NUM> in order to pass to atmosphere. The filter <NUM> is attached by an adhesive connection, although it could be connected in any appropriate way, for example heat welding.

The filter <NUM> is a multi-layered filter as shown in more detail in <FIG>. The multi-layered filter <NUM> preferably consists of three layers (although it could have more layers), including a hydrophobic layer <NUM>, a de-odorising layer <NUM> and a gas and liquid impermeable layer <NUM>. The multi-layered filter <NUM> is preferably constructed (but not limited to) in the order of hydrophobic layer <NUM>, de-odorising layer <NUM> and gas and liquid impermeable layer <NUM>.

The hydrophobic layer <NUM> is preferably Polytetrafluoroethylene (PTFE). The hydrophobic nature of PTFE ensures that water molecules are repelled from its surface, meaning that any interaction between the surface of the PTFE layer and water molecules is substantially resisted, and thus, the PTFE layer is waterproof. The hydrophobic layer <NUM> of the multi-layered filter <NUM> is advantageously positioned directly adjacent the second wall <NUM> so as to directly and completely cover the aperture <NUM> provided in the second wall <NUM>. The hydrophobic layer <NUM> has a first side and second side with the first side connected directly to the second wall <NUM>, said connection holding the multi-layer filter relative to the wall <NUM>. The hydrophobic layer <NUM> is connected directly to the second wall <NUM> preferably by an adhesive, e.g. a holt melt adhesive or double-sided tape. Therefore, the hydrophobic layer <NUM> is in direct fluid communication with the waste collecting chamber <NUM> such that any waste gas exiting the ostomy appliance <NUM> must travel through the hydrophobic layer <NUM> first. The advantage of providing the hydrophobic layer <NUM> directly adjacent the aperture <NUM>, and thus facing inwards towards the interior of the appliance <NUM>, is that no liquid waste collected in the waste collecting chamber <NUM> can pass through the hydrophobic layer <NUM> and into contact with the other layers of the multi-layered filter <NUM>. This reduces the risk of the filter, in particular the de-odorising layer <NUM>, from getting damp and/or clogged. A damp and/or clogged filter can lead to ballooning of the ostomy appliance which can significantly reduce the effectiveness of the filter and the appliance. This will inevitably lead to the user having to replace the flawed ostomy appliance at a cost to the user.

Further to this, the multi-layered filter <NUM> is advantageously positioned on an external surface of the second wall <NUM> such that the de-odorising layer <NUM> and gas and liquid impermeable layer <NUM> cannot come into direct contact with the waste collected in the waste collecting chamber <NUM> which significantly reduces the risk of the filter <NUM> from getting damp and/or clogged. Further to this, providing a filter <NUM> externally of the ostomy appliance <NUM>, e.g. external of the wall or walls which form the waste collecting chamber, allows for an easier and thus more cost effective manufacturing process as there is no need to place the filter carefully between layers of the ostomy appliance before they are connected together. Instead, the filter <NUM> can, if desired, be attached to the ostomy appliance once the walls of the appliance have been sealed together around its peripheries.

The de-odorising layer <NUM> is preferably a layer of carbon based de-odorising material that is positioned directly adjacent the hydrophobic layer <NUM> such that it lies on an opposite side of the hydrophobic layer <NUM> to the aperture <NUM> and wall <NUM>. The de-odorising layer <NUM> receives waste gas travelling from the hydrophobic layer <NUM> and de-odorises the waste gas such that it is ready to exit the de-odorising layer <NUM> into atmosphere.

The gas and liquid impermeable layer <NUM> is preferably a layer of Cryovac™ material that does not allow gas or liquid to pass through its surface. The gas and liquid impermeable layer <NUM> is positioned directly adjacent the de-odorising layer <NUM> such that it lies on an opposite side of the de-odorising layer <NUM> to the hydrophobic layer <NUM>. The gas and liquid impermeable layer <NUM> advantageously partially protects the de-odorising layer <NUM> from getting damp and/or clogged by moisture that is provided externally of the ostomy appliance, for example when a user is showering.

Referring to <FIG>, arrows <NUM>, <NUM> show the directional flow path taken by waste gas when exiting the waste collecting chamber <NUM> through the filter <NUM>. Firstly, the waste gas travels through the aperture <NUM> and into the hydrophobic layer <NUM> in a direction substantially perpendicular to the second wall <NUM>. Thereafter the waste gas continues to travel through the hydrophobic layer <NUM> and into the de-odorising layer <NUM> in a direction substantially perpendicular to the second wall <NUM>. Finally, the waste gas travels through and exits the de-odorising layer <NUM> in a direction substantially parallel to the second wall <NUM>, i.e. radially away from an axis of the filter <NUM>. The positioning of the gas and liquid permeable layer <NUM> directly adjacent the de-odorising layer <NUM> ensures that all gas entering the filter passes through the de-odorising layer in a direction substantially parallel to the second wall <NUM>.

<FIG> show a second embodiment of an ostomy appliance <NUM>. Features which are in common with the first embodiment <NUM> have been given the same reference numeral with the addition of <NUM>. Those features will not be discussed again here.

Referring to the second embodiment the main difference is the size of the aperture <NUM> in relation to the multi-layered filter <NUM>. Instead of the aperture <NUM> being significantly smaller in diameter than the filter <NUM>, the aperture <NUM> is substantially the same diameter as the filter <NUM>. This provides for an increased area through which the waste gas can exit the ostomy appliance through the aperture <NUM> and into and through the hydrophobic layer <NUM> and further reduces the risk of the aperture <NUM> becoming completely blocked with waste. The flow through the aperture <NUM> and multi-layered filter <NUM> is substantially the same as that of the first embodiment, as shown by arrows <NUM>, <NUM>.

Whilst in the described embodiments the filter is shown as circular in front view, it should be appreciated that other shapes of filter could be used without departing from the scope of the present invention. In addition, whilst the filter described above has three layers, it should be appreciated that a two layer filter could be used, but also filters of four or more layers could be used.

Claim 1:
An ostomy appliance (<NUM>, <NUM>) comprising:
first and second walls (<NUM>, <NUM>, <NUM>, <NUM>) connected to each other at or near their peripheries, the first wall having a stoma-receiving opening (<NUM>, <NUM>);
a connection member (<NUM>, <NUM>) connected to the first wall for attaching the appliance to a user;
an aperture (<NUM>, <NUM>) located in either of the first and/or second walls for permitting waste gases to exit the appliance;
a multi-layer filter (<NUM>, <NUM>) positioned adjacent and covering the aperture on an exterior surface of the respective first and/or second wall,
wherein a layer of the filter is hydrophobic (<NUM>, <NUM>) and wherein said hydrophobic layer is positioned directly adjacent the respective first and/or second wall,
wherein the filter includes a de-odorising layer (<NUM>, <NUM>) positioned directly adjacent the hydrophobic layer; and
wherein the filter includes a gas and liquid impermeable layer (<NUM>, <NUM>) positioned directly adjacent the de-odorising layer;
wherein the layers of the filter are arranged in the order of hydrophobic layer, de-odorising layer and gas and liquid impermeable layer;
wherein the hydrophobic layer has a first side and a second side and wherein the first side is connected directly to the respective first and/or second wall, said connection holding the multi-layer filter relative to the wall;
wherein waste gas travels through the aperture in a direction substantially perpendicular to the first and/or second wall; and
wherein waste gas travels through the de-odorising layer in a direction substantially parallel to the first and/or second wall.