This invention relates to the field of ostomy products, and in particular to a coupling for releasably attaching an ostomy pouch to a pad or wafer worn on the body. The term xe2x80x9costomyxe2x80x9d is intended to be interpreted broadly, and includes colostomy, urostomy and ileostomy.
In one form, the invention relates to a so-called two-piece coupling consisting substantially of only two coupling members, one for the bag side of the coupling and the other for the body side.
There are many different designs of two-piece coupling. Typically, the mutually engaging regions of the bodyside and bagside coupling members result in a deadspace being created between the pouch and the body pad or wafer; in other words, the pouch is held away from the pad by a distance corresponding to the xe2x80x9cheightxe2x80x9d of the coupling. Generally, it is desired that the coupling members have a low profile, so as to keep the deadspace to a minimum.
A coupling has been proposed in U.S. Pat No. 4,872,869 in which the ostomy pouch is a flush fit, or almost a flush fit, against the body pad. Such an arrangement is referred to herein as a flush-fit coupling.
Broadly speaking, in a first aspect, the invention provides a flush-fit coupling including a bagside coupling member and a bodyside coupling member securable together.
The coupling preferably has one or more of the following features:
1. The bagside coupling member includes an inner first wall, and an outer second wall defining a connection channel therebetween, and of the first and second walls, one of said walls comprises or carries a locking projection facing the interior of the channel, the surface of the other wall facing the channel being a generally smooth sealing surface.
Such an arrangement can provide significant technical advantages, over the prior art.
In particular, the coupling described in the aforementioned U.S. Pat. No. 4,872,869, relies on locking profiles on both of the cylindrical walls defining the channel of the bagside coupling member. The locking profiles act in combination with a central rib, to trap the connecting part of the bodyside member in the channel. The interlocking regions have a dual function in providing a seal and a secure fastening.
However, in developing the present invention, it was appreciated that a user may have severe problems trying to release the aforementioned prior art coupling to separate an ostomy pouch from the body part after use. The problem arises because the connecting part of the bodyside member is interlocked by both the channel walls, and is also expanded by the rib in the channel. This can make it virtually impossible to withdraw the connecting part from the channel, without twisting or deforming the channel somehow. The above problem is magnified by the coupling being recessed inside the pouch. Even flexing of the front flange of the bagside coupling member would provide little assistance to releasing both channel walls, since the recessed design of the coupling member means that the front flange is not coupled directly to the base of the channel.
Such a coupling thus requires considerable dexterity to release, and would provide problems for many ostomates, who are often elderly and may not have much strength in their fingers.
However, with the present invention, by providing different wall portions to provide a sealing function (i.e. either the inner, first wall, or the outer, second wall) and a locking function (i.e. either the outer, second wall, or the inner, first wall, respectively), many of the above problems can be avoided. The coupling can be made much easier to release without having to weaken the seal, and without having to weaken the security of the coupling.
Preferably, the wall carrying the locking projection carries a plurality of locking projections. For example, the locking projections may be spaced apart angularly.
In a closely related specific aspect, the invention provides a flush fit ostomy coupling, comprising:
a bagside coupling member comprising an inner first wall and an outer second wall defining a channel therebetween, a mounting flange extending outwardly from the second wall at the mouth of the channel, one of the first and second walls comprising at least one locking projection facing the first wall;
a bodyside coupling member comprising a projection which, in use, is received within the channel of the bagside coupling member, the projection including a formation for interlocking engagement with the locking projection of one of said walls of the bagside coupling member, and a deflectable seal for non-interlocking engagement with the other wall of the bagside coupling member.
2. The bagside coupling member is secured to an ostomy pouch comprising first and second pouch walls and having an entrance aperture in the first pouch wall, the bagside coupling member being carried by the first pouch wall at the aperture, at least a portion of the bagside coupling member extending inside the pouch. Anti-sealing means is provided for preventing in use sealing between a portion of the bagside coupling member and the interior face of the second pouch wall.
This feature of the invention can avoid the potential problem of, for example, the front wall of the pouch opposite the coupling member tending to stick to the coupling member when the pouch is first used. This effect is similar to the problem of pancaking in which the front and rear walls of the pouch can sometimes stick together, and obstruct the entry of body waste into the pouch. The use of a coupling member extending at least partly inside the pouch can actually reduce the effect of direct pancaking between the front and rear walls at the aperture (by holding the walls apart to some extent), but there is then the potential problem of the pouch wall tending to seal or stick to the coupling member, which again would obstruct entry of body waste into the pouch. However, by using anti-sealing means in accordance with this aspect of the invention, this potential problem can be avoided or at least reduced.
The anti-sealing means may comprise a non-planar surface of the coupling member, for example, one or more projections or recesses, or an undulating surface, to promote channels or spaces being created between the coupling member surface and the opposing face of the pouch wall. Alternatively, the anti-sealing means may comprise a non-stick coating carried by the coupling member and/or by the pouch wall.
In a closely related specific aspect, the invention provides a bagside coupling member for a flush fit coupling, the bagside coupling member comprising a coupling channel, and anti-sealing means on the rear surface of the channel.
3. The bagside coupling member is carried by an ostomy pouch comprising first and second pouch walls, there being an entrance aperture in the first pouch wall, the bagside coupling member being carried by the first pouch wall at the aperture, at least a portion of the bagside coupling member extending inside the pouch, and a surface of the bagside coupling member confronting the second wall being substantially non-planar.
In addition to any non-sealing effect, this feature can improve the extent to which a user is able to feel by hand the profile of coupling member through the pouch wall material, to enable the user better to position his hands during fitting of the pouch to the body, and during removal of the pouch from the body. During the development of the present invention, it has been appreciated that the recessed nature of the xe2x80x9cflush-fitxe2x80x9d bagside coupling member results in the coupling being considerably more hidden from the user""s view. This loss of visibility can make the coupling more difficult to fit and remove. Therefore, improving the tactility of the coupling through the second pouch wall can compensate for loss of visibility of the coupling member.
In one preferred embodiment, the surface comprises a plurality of spaced apart projections, for example, small domes. In another embodiment, the surface comprises an annular projection.
In a closely related specific aspect, the invention provides a bagside coupling member for a flush fit coupling, the bagside coupling member comprising a coupling channel, a surface of the coupling member directed away from the open mouth of the channel being substantially non-planar to enable said surface to be felt by hand through a pouch wall.
4. The bagside coupling member comprises a channel defined by first and second wall portions and a base portion between the first and second wall portions, at least one of said portions comprising a region of reduced thickness.
With this aspect of the invention, the region of reduced thickness provides a natural hinging effect to enhance the extent to which the channel can open when the bagside coupling member is assembled to, or is separated from, a body-side coupling member. During the development of this aspect of the invention, it was appreciated that the concept of a recessed channel for a xe2x80x9cflush fitxe2x80x9d bagside coupling member is more problematic than an external coupling member, because as explained above, in a recessed design the channel is supported around its mouth rather than around its base. This means that the channel is stiffer, and is not free to xe2x80x9copenxe2x80x9d in the same way as a channel supported at its base. Moreover, in a recessed design, the channel is inaccessible, and it is generally more difficult to flex the recessed channel when the bag-side and body-side coupling members are to be released.
However, by using this aspect of the invention to enhance the extent to which the channel can open, the above problems can be substantially alleviated.
Preferably, the first and/or the second wall portion of the channel comprises a region of reduced thickness. In some preferred embodiments, the first and/or the second wall portion is tapered to thin towards the base portion. Additionally, or alternatively, the base portion may include one or more recesses which can enhance the flexibility of the channel base.
5. The bagside coupling member is secured to an ostomy pouch comprising first and second walls, there being an entrance aperture in the first wall, and the bagside coupling member being carried by the first wall at the aperture, the bagside coupling member comprising a channel at least a portion of which extends into the interior of the pouch, the channel being defined by generally concentric outer and inner walls, wherein the inner wall projects through the aperture from the interior of the pouch to the exterior, and the inner wall is proud of the outer wall.
With this feature, there is a step in the relative heights of the inner and outer walls.
Preferably, the outer wall carries or comprises at least one locking projection. Preferably, the inner wall provides a planar sealing surface.
This feature of the invention can provide a recessed coupling with a relatively large wall surface for forming a seal with a body-side coupling member, without increasing substantially the depth of the coupling member within the interior of the pouch. It will be appreciated that it would be undesirable to have too great a depth of coupling within the pouch, as this would cause the pouch to bulge in the region of the coupling.
In a closely related specific aspect, the invention provides a bag-side coupling member for a flush fit coupling, the bagside coupling member comprising a mounting flange, a first wall portion depending from the flange, a second wall portion concentric with the first wall portion and defining therewith a connection channel, the second wall portion being proud of the first wall portion.
Another aspect of the invention relates to sealing means for forming a seal between a bagside coupling member and a bodyside coupling member. This aspect of the invention is applicable to a flush-fit coupling as well as to a non-flush-fit coupling. This aspect is also applicable to two-piece couplings, and to multi-piece couplings. It is also applicable to couplings which are secured together mechanically as well as to adhesive couplings.
There are many different designs of seal. A particularly successful design used in a mechanical interlock coupling is illustrated for example in GB 1 571 657. This design includes a cylindrical rib which is received within an annular channel. The outer edge of the rib has a profile which interlocks with the inner edge of the outer channel wall to hold the coupling parts together in use. The rib also has an inwardly inclined frusto conical wiper which forms a seal against the inner wall of the channel.
The above design has proven to be extremely reliable in practice. The wiper is able to deform sufficiently to accommodate tolerance variations and relative movement of the coupling members. However, the minimum profile xe2x80x9cheightxe2x80x9d of the coupling which can be achieved is limited by the presence of the wiper, which must have at least a certain minimum length. The wiper cannot be shortened significantly, as this would affect the seal integrity and the ability to accommodate size variations.
In general, a low profile is desirable as this reduces the dead-gap between the ostomy pouch and the person""s body (for non-flush-fit couplings), and also reduces the prominence of the pouch (for flush-fit and non-flush-fit couplings).
Reference is also made to GB-A-2 157 567 which discloses an adhesive coupling in which an inwardly extending lip of the ostomy pouch material stretches to form a tight fit around the chute of a body side member. This design suffers from manufacturing problems in that it relies on forming an accurately sized opening in the pouch wall. Moreover, it relies on accurate positioning of the aperture and of the bagside coupling member around the aperture. Such tolerances require very expensive manufacturing machinery for large scale production. A further problem is that the seal relies on the characteristics of the pouch material, which might not be ideal to form a resilient seal.
This aspect of the invention has been devised bearing the above in mind.
In contrast to the prior art, the present aspect of the present invention is to provide a closed-loop shape sealing fin projecting generally laterally (at least in one operative condition, for example, a non-deformed condition) from a wall or chute portion of a coupling member, the sealing fin being of resiliently flexible material and being distinct from the pouch wall.
When the wall or chute carrying the fin is on the bag-side coupling member, preferably the fin extends from a position which is offset axially, at least to some extent, relative to the joint between the coupling member and the pouch wall material.
This aspect of the invention can provide significant advantages over the prior art arrangement as follows:
(a) the seal performance is not limited by the accuracy of the position of the coupling member relative to the stoma aperture in the pouch wall, nor is it limited by the exact size of the stoma aperture in the pouch wall. This enables conventional assembly machines which have modest tolerances to be used for mounting the coupling member on the pouch, and for punching the stoma aperture in the pouch wall material.
(b) The seal performance is not limited by the specific properties of the pouch wall material;
(c) The seal fin can be made of relatively soft resilient material. This can provide an excellent seal with only low assembly (insertion) forces being required;
(d) A coupling member can be constructed which has a very low profile. For example, compared to integral frusto-conical deflectable wipers, a smaller insertion depth might be achieved while still obtaining a reliable seal.
(e) The flexibility of the fin can enable wider dimensional tolerances to be accommodated than in some prior art designs, without reducing seal performance.
Preferably, the body-side and bag-side coupling members are configured such that the fin projecting from the chute on the member engages against the surface of a second chute wall (or cylindrical wall) on the other coupling member. Preferably, the chutes fit one inside the other when the coupling members are assembled together.
The fin may be provided on the bagside coupling member, or on the bodyside coupling member.
The coupling member may include one such fin, or two fins, or more fins, as desired.
The coupling member including the fin may be produced by a variety of techniques. Examples include:
(a) multi-shot (e.g. two shot) moulding;
(b) insert injection moulding (similar to multi-shot moulding, but with this technique the plastics material is allowed to set before the next plastics is moulded);
(c) fabrication using a plurality of pre-formed components which are in turn assembled to form a finished item, retained in its assembled condition by mechanical interlocking, adhesive or welding; or
(d) integrally moulding the member integrally of a flexible polymer, for example, using injection moulding.
Another related aspect of the present invention is to use one or more sealing elements carried by, and extending or projecting generally radially from, a first wall of the coupling, the one or more sealing elements being formed from a plastics material which is softer than the material of the first wall.
In a preferred form, the one or more sealing elements extend or project generally radially at least in an undeflected state (for example, when the coupling members are separated).
The combination of a generally radially extending or projecting seal, and the seal material being of generally softer material then the or a structural part of the coupling, can enable a low coupling profile to be achieved without impairing the characteristics of the seal.
Such a design is especially suitable for a two piece mechanical interlock coupling, but it is also suitable for use in many other types of coupling, for example, types including a locking ring, or types secured together by adhesive.
Preferably, the one or more sealing elements are integrally moulded with the first wall. For example an insertion injection moulding process, or a multi-shot moulding process may be used. Reference is made to the techniques described in GB-A-2 323 285.
Preferably, in either of the above aspects, at least one sealing element or fin forms a seal spread axially over a cylindrical band or region, rather than forming a so-called xe2x80x9cpoint sealxe2x80x9d at only one axial point. By spreading the seal axially, the seal is better able to withstand relative movement or distortion of the coupling members without loss of seal integrity.
Preferably, at least one sealing element or fin is in the form of a deflectable wiper which will deflect to some extent upon contact with the opposite coupling member. Such deflection can ensure that the sealing element bears on the opposite surface with a modest but sufficient force to achieve a seal, and preferably also can enable the above larger area (cylindrical band) seal to be achieved.
Preferably, at least one sealing element or fin is tapered towards its free edge.
Preferably, at least one sealing element or fin is distinct from the material of the ostomy pouch. Preferably, the sealing element lies in a plane which is offset from the plane of the ostomy pouch material.
If desired the one or more sealing elements could project radially inwardly from the first wall of the coupling member. However, in a particularly preferred form of the invention, the one or more sealing elements project radially outwardly from a cylindrical rib of the coupling member. Such a design can facilitate easier moulding when a plurality of sealing elements are used.
In a closely related aspect, the invention provides a first coupling member for use in a two piece ostomy coupling of the type including first and second coupling members releasably securable together by a mechanical interlock, the first coupling member comprising a first portion of a first relatively rigid plastics material integrally moulded with a second portion of a second relatively soft plastics material, the first portion comprising a locking profile for forming a mechanical interlock with the second coupling member, and the second portion comprising a sealing element.
In a closely related aspect, the invention provides a first coupling member for use in a coupling of the type including first and second coupling members which are mechanically securable together, the first coupling member comprising a least one generally annular sealing fin which projects generally radially from a cylindrical wall, the fin tapering in thickness towards its free edge.
The above aspects of the invention may be used independently, but further advantages may be achieved by using tow or more aspects in combination.