Gas filter arrangement for ostomy or ileostomy bags

An ostomy bag has a filter attached to it by a series of plural sequentially peelable adhesive annuli.

BACKGROUND OF THE INVENTION 
This invention relates to a gas filter arrangement for ostomy bags, and to 
ostomy bags, particularly ileostomy bags, including gas filter 
arrangements. 
There have been numerous prior proposals for gas filters for ostomy bags, 
of which the following patent specifications can be mentioned as a 
representative selection: U.K. No. 2,053,718; U.K. No. 2,122,090; U.K. No. 
2,116,433; U.K. No. 2,031,282; U.K. No. 1,405,032; U.K. No. 1,550,960; 
U.K. No. 2,145,334; U.K. No. 2,149,306; U.K. No. 2,083,760; U.K. No. 
1,379,464; U.S. Pat. Nos. 3,690,320; 3,865,109. 
Particularly with ileostomy bags, one of the problems in bags having a 
filter is that the filter may become blocked due to the discharge being 
part-liquid, part-solid or of a slurry-like nature. Efforts have been made 
to design bags and pouches which meet the apparently conflicting 
requirements of preventing the discharge from reaching the filter and yet 
allowing gases within the bag to readily reach the filter. To the best of 
the applicant's knowledge and belief, there has been no satisfactory 
solution despite numerous efforts in the prior art, to the problem of 
allowing a wearer to make a quick and easy replacement of a filter which 
has become ineffective. Provision is made in various prior proposals for 
changing a used filter for a new filter. The constructions proposed are 
often complex, expensive to manufacture and awkward to manipulate. For 
example, U.K. Application No. 2 031 282 discloses a filter 6 placed over a 
vent hole in a bag. This filter would appear to be permanently attached to 
the bag, so, when its effectiveness reduces, a new bag would be required. 
U.K. Pat. No. 2,083,760 and U.S. Pat. No. 4,449,970 disclose a flatus 
filter which is folded over a top edge to cover perforations in each of 
two walls of a bag. With this arrangement one can remove an ineffective 
filter and replace it with a new filter but the manipulation necessary to 
peel or tear off the old filter and fold over and fit the new filter 
properly aligned with pinholes in the bag walls which are probably not 
easily visible is a difficult or impossible task for many users. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an ostomy bag has a filter 
attached to it by a series of sequentially peelable adhesive annuli. 
The invention also comprehends a stack of adhesive annuli which are 
sequentially peelable and which are for use with an ostomy bag or pouch 
(in particular an ileostomy bag). 
The invention also provides a method of changing a flatus filter on an 
ostomy bag which comprises peeling off one adhesively-attached filter in 
such a way as to expose an adhesive surface on an annulus which is lower 
down in a stack of adhesive annuli, and sticking a new filter on to the 
adhesive so exposed. 
The bag may be constructed as a two-compartment bag, there being an 
intermediate dividing wall constituted by a plastics film which is partly 
or wholly perforated. The perforation holes are preferably circular in 
shape (although they may be of any shape) and they preferably have a 
maximum dimension (a diameter in the case of a circular hole) which is in 
the range of 2-15 thousandths of an inch, i.e. substantially 0.05 to 0.38 
millimeters. The purpose of this intervening wall is to inhibit access of 
the liquid or slurry-like faecal material to the filter but to 
nevertheless allow flatus gases to pass through the intervening wall and 
reach the filter. The intervening wall may be secured in a position by the 
same peripheral weld which joins the bag walls together. In this context, 
it will be understood that it is conventional for ostomy bags to be made 
of front and rear walls of plastics film superposed one upon the other and 
joined together around the periphery (or around the major part of the 
periphery) by a weld. This construction and procedure being conventional, 
it need not be further described; reference may be had for example to 
British Patent Specification No. 2,058,011 or 2,031,282. 
The intervening wall may be perforated over its whole area or over its 
upper region only. It may extend any desired distance downwardly within 
the bag; that is, it may extend completely to the bottom of the bag, or 
merely to a lower region of the bag, near to the bag outlet, or 
approximately half-way down the bag. Its lower edge may if desired be 
intermittently welded to the bag front and rear walls. An intermediate 
wall configuration similar to that shown at 30,32 in FIG. 2 of U.K. 
published patent application No. 2, 149 306 may be employed. The plastics 
film of the intervening wall may be the same as the inner and outer bag 
walls, for example it may be made of a polymer, e.g. ethylene vinyl 
acetate or polyvinylidene chloride or it may be a laminate whose layers 
may by EVA, PVDC, and/or other plastics film materials conventionally used 
for this purpose. The perforations may be provided by a "needling" 
operation. 
An advantage of the present invention over the prior art is that action can 
easily be taken, without awkward manipulation, and without removing the 
bag, to ensure that a new filter is exposed to the exiting flatus gases. 
This is done by peeling off the filter (and the uppermost adhesive annulus 
attached thereto) from the bag by separating this annulus from the next 
one of the sequence, and then placing a new filter on the freshly exposed 
adhesive of the next underlying annulus. 
The invention will be better understood from the following description of 
illustrative embodiments thereof, given by way of example with reference 
to the accompanying drawings in which:

DETAILED DESCRIPTION OF THE DRAWINGS 
In the drawings, like parts are denoted by like reference numerals. 
The illeostomy bag illustrated in FIGS. 1 and 2 has a front wall 10, a rear 
wall 12 and an intervening wall 14 with circular perforation holes 30. 
These walls are secured together by a peripheral weld 16. The bag so 
produced has a bottom outlet 18, and the intervening wall does not extend 
completely to the bottom of the bag. Its bottom edge is indicated at 20. 
A stomal orifice 22 is provided in the rear wall 12, and this is surrounded 
by an ostomy coupling element 24. The coupling element 24 is preferably of 
the kind described and claimed in British Patent No. 1,571,657 and in 
counterpart patents and patent applications throughout the world. However, 
other forms of ostomy coupling elements may be employed. The purpose of 
such an element is, as is well known, to connect the bag to a pad or face 
plate or surgical grade adhesive material which is attached to the 
peristomal area of the person wearing the bag. 
The front wall 10 has a hole 70 in its upper region. An annular region 
surrounding the hole is covered with adhesive 60. Placed upon this 
adhesive is a bottom annulus of a series or stack 62 of sequentially 
removable annuli. Each of these has adhesive on it and in use the bottom 
one is the last to be removed. Each of these adhesive annuli has a 
gripping tab constituted by a circular portion integral with the adhesive 
annulus. That is to say, each adhesive annulus resembles a FIG. 8 in 
shape, one loop of the 8 being the gripping tab and the other loop being 
constituted by an annulus bearing adhesive with the center hole of the 
other loop being aligned with the hole 70. In FIG. 1, the gripping tab 
loops are seen at 72, 74, 76, 78 and 80, 80 being the bottom and 
last-removed annulus. In FIG. 3A only three annuli are shown for 
illustration purposes with gripping tabs 80, 78 and 76. A filter 71 is 
placed on top of the top annulus 72, and secured thereto by adhesive. 
In use, when wearing the ileostomy bag according to FIGS. 1 and 2, and when 
the wearer believes that the filter may need replacement, he or she grasps 
the tab 72 and separates it from the remaining tabs by placing a thumb or 
finger on tab 74 and pulling tab 72 upwards. In this way, the filter 71 is 
removed, and thereafter a new filter is pressed straight on to the exposed 
fresh adhesive on annulus 74, this having been exposed by removal of the 
annulus 72. In a similar way, freshly exposed adhesive annuli 76, 78 and 
80 of the stack 71 can be used in turn to attach three new filters without 
the ileostomy bag being removed from the wearer. 
The bottom edge of the intervening wall is seen at 20 in FIG. 1 but this 
wall may extend completely to the bottom of the outlet position 21 of the 
bag, if desired. 
As an alternative to using annuli which have adhesive on one side, annuli 
which have adhesive on both sides designated generally 66 may be used 
interleaved with perforated discs or annuli of release material 68, e.g. 
silicone-coated paper or plastics film. Release annuli may alternatively 
be interleaved with single sided adhesive annuli. 
In this specification, the words "annulus" and "annuli" are used without 
strict geometrical connotation. These words are intended to cover any 
shape of element having a central hole, this being necessary to allow 
passage of flatus gases, surrounded by a closed loop surface upon which 
adhesive can be carried. 
While the gripping tabs have been illustrated as having a substantially 
circular shape, it will be realized that the invention can be carried into 
practice, and its advantages achieved, with tabs of various shapes. 
Any suitable filter may be employed as the filter 71 although a filter as 
disclosed in our U.K. Patent Application No. 8503 749 is preferred. 
In accordance with the description of a suitable filter taken from pages 2, 
4 and 5 of U.K. Patent Application No. 85 03749, the gas filter 
illustrated in FIG. 4 has a first membrane 40, a second membrane 42, and 
between these is sandwiched a pad 44 of carbon impregnated polyurethane 
foam. 
These three parts are secured together in any convenient way so that they 
are integrated into a single unitary gas filter. The edges are sealed so 
as to prevent gas escape by a sealant such as a cement 46 around the 
periphery. A thin layer 48 of water-repellent material (its thickness is 
exaggerated for clarity in FIG. 4) covers the upper surface (as seen in 
FIG. 4) of the microporous membrane 42. The thickness of the layer 48 is 
preferably only a few hundredths of a millimeter. 
The pad 44 is reticulated polyurethane foam having the following 
characteristics: 
Density: 27-30 KG/M.sup.3 
Compression resistance: 3.4-4.6 KPA 
Ultimate elongation: 350% 
Tensile strength: 200 KPA 
Tear strength: 6N/cm 
Porosity: 65-85 (PPI) 
The microporous membrane 40 and 42 are each a polyurethane film or foil 
0.10 to 0.15 mm thick having controlled-size microporous holes therein. 
The layer 18 is water-repellent polytetrafluroethylene (PTFE).