Note: Descriptions are shown in the official language in which they were submitted.
''3~
Field of the invention~
.
This invention relates to improvernents
in the post surgical ostomy devices used for
preventing the escape of gaseous, liquid,
and solid wastematerials from the stoma of
ostomy patients or from anus with insufficient
will control of the anus closing ring muscle.
More specifically, the invention relates to
devices for venting stomas and other discharge
openings for metabolic products from the
human body.
A surgical procedure such as colostomy,
ileostomy or ureteromy comprises the
formation of an opening, or stoma, in the wall
of the intestine or urethra so as to form a
channel to the outer world through the body
wall and skin of the patient. The stoma provides
a means of communicatlon between the intestine
or urethra and the external world so as to
permit the excretion of excretions such as
fecal material or urineO As the excretion
cannot be controlled by the will in the same
manner as excretions from the normal body
openings, it is necessary for the patient to
wear some sealing device which may comprise
a collecting device. Actually, it is quite
common for ostomy patients to wear some form
of a 'stoma bag' or 'stoma pouch' for the
rest of their life.
The most widely form for collecting receptacle
- 30 is a bag or pouch made of film or foil of a
transparent polymer material, affixed to the
- 2 ~
rJ 4~ ~
abdomen of -the patien-t by rneans of a
double-sided adhesive disc with a central
opening registering with the stoma; the
stoma may be slightly projectiny from the
abdomen and passed through the central
opening of the adhesive disc. In another
embodiment a flange made of relatively stiff
material such as a suitable polymer is
secured to the back panel of the pouch, for
instance by heat sealing; and a sealing gasket
isaffixed between the flange and the skin of
the patier.t, whereby the pouch is held in
position by means of a belt attached to the
flange.
Fecal material is collected more or
less constantly in the pouch and after a
period, usually several hours, the pouch is
discarded and replaced by another. The length
of the period during which any given pouch
may be used is strongly influenced, however,
by the rate of production of flatus, i.e.
of instestinal gases.
Several factors such as kind of food
eaten, type of microflora and psychic condition
affect the production rate and the composition
of the intestinal gases. Over a 12 hours
- period the amount ~ay vary between 50 and 1000
ml or even more. Generally the volume of
; flatus and intes-tinal gas passed via rectal
tube ranges from about 400 to about 1200 ml
per day. The commonly held belief that certain
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foods produce flatulence has heen well documented.
Ingestion of beans, fpr instance, may increase
the mean flatus excretion ra-te from 15 ml to
176 ml per hr. The rate over shorter periods
of time may show wide variations, and it is
particurlarly the flatus released at high rate
which is difficult to deodorize and also
most likely to createproblems for the patient.
Thus, the variations 1n amounts and composition
of flatus in themselves give great problems.
The composition of the intestinal gas depends
in part upon the site in the gastro-intestinal
tract from which it is obtained. Stomach gas
usually has a composltion relatively similar
to that of atmospheric air, for example 78% N2,
17% 2' 3% CO2. ~latus in general contains
less than 2% oxygen with the remainder of the
gas consisting of varying proportions of
nitrogen, carbon dioxide, hydrogen, methane
and trace components. Keizo Kodama and Yoshiaki
Miura in J.Japan Soc. Food Nutrition 2,
pages 149-152 (1949) give the following
composition: CO2 13-34%, CH4 19-26%, H2 20~27%,
N2 17-48%. The odoriferous gases include indole,
skatole, volatile amines, and hydrogen sulfide,
and represent normally less than 1~ of flatus.
Of these gases hydroyen sulfide is by far
the major component and presents the worst
problem since lt is readily detected by the
nose in concentrations as low as 1 part in
100 million.
X - 4 _
The gases enter 'che drainage pouch and
expand it which gives rise to both practical
and psychic problems ~or the patient. It
has been practice to teach him to vent the
gases from the pouch by puncturiny the upper
part of the pouch with a needle and after
the exit of the gases seal the puncture anew
with adhesive tape. However, because of the
obnoxious nature of some of the yases and the
frequency with wich i~ is necessary to vent
the pouch, this solution is quite unsatisfactory
and may give rise to embarrassing situations.
Therefore, it is known to provide the pouch
with some sort of filter to allow escape of
gases.
Another manner of sealing the stoma
of ostomy patients is to close it by a so-
called stoma-cap, which is afixed to the
body in much the same manner as the drainage
pouch. A third and more important is to close
the stoma by a plug or a stopper-like device
inserted into the stoma and maintained in
position by a flange or cover plate the inner
face of which is in contact with the skin of
the abdomen around the stoma. Such stopper
may be maintained in po~ition hy magnetic
foxce, small permanent magnets being sewn
into the body of the patient around the
stoma by a surgical operation. There is no
drainage pouch, but the fecal material is
ramoved from time to time by irrigation, e.g.
every two days, after removal of the plug and
subsequenk re-insertion of it. To prevent
pressure-build up behlnd the plug (or behind
the stoma cap), we have suggested to
provide it with a venting opening covered
with several layers of non-woven textile
containing active carbon. In practice the
gases are not, however, made non-odorous by
the passage through this filter, possibly
10- because the path passed by the gasses through
the filter is very short. Accordingly, this
device may also give rise to em~arrassing
situations.
Background of the invention
As will be understood it is known in
the three forms of sealing devices for stomas
to insert a filter at some suitable spot of
the path o the gases. Several such filters
are known. Thus, a preferred embodiment of a
filter known from US Patent Specification No.
3,759,260 comprises a disc of matted fibres
and activated granulax carbon having one
suxface overlying the inner side of the ven-t
aperture of the pouch and an area surroundiny
the aperture~ and an impervious cover over
the opposite surface of the disc, whereby
the gases to be vented pass radially through
the disc from the perphery to the vent
aperture placed centrally relative the filter.
This does not function quite satisfactory,
.
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which is believed to be due to the short
path passed by the gaSes and, perhaps most
important, a tendency to a channelling e~fect
to-be discussed later in this text.
A filter for venting gases from stoma
pouches is described in Danish pa-tent specifi-
cation No. 130,277, h;aving a priority rom
US patent application Serial No. 290,149 of
18th September, 1972. The preferred embodiment
of this comprises a square disc of matted
fibres and activated carbon in granular form.
One surface is covered with a gas-tight material
with a central venting aperture, whereas the other
surface of the disc is covered with another
cover of gas-tight material with several
apertures displaced relative the centre,
whereby the gases to be exhausted pass through
an oblique, partly radial path trough the
filter~ A similar filter is disclosed in
Danish patent specification No. 133,080,
having priority from US patent application
Serial No. 401,337 of 27th September, 1973.
In this , one of the impervious covers has
a central venting aperture and the opposite
cover several venting apertures evenly distribu-ted
over the area of the filter dlsc.
The prior art filter devices described
are similar in that they all comprise a flat
disc of matted fibres and activated granular
carbon, said disc having the two opposite faces
covered with impervious materials with
- 7 -
apertures so that the gases to be exhausted
are forced to pass in a more or less radial
direction through the filter, i~e. by a
path longer than the Lhickness of the disc.
The purpose of this is to make more effective
use of the capacity oE the activated carbon
for absorbing the odorous constituents of
the intestine gases. However, in practice
the known filter assemblies do not function
as intended and the useful lifetime of filters
are not satisfactory whereby despite of the
use of filters there may arise embarrassing
situations; also frequent removals and re-
placements of the filters are needed and
the active carbon present is not utilized full,
which means an extra financial burden.
It is believed that one reason for
the unsatisfactory function of the known
filters described is that a considerable
'channelling' takes place during the passage
of the gases. The filter disc is made of
comparatively stiff material. The gas-tight
covers are made of thin films or foils of
plasti~ with no special precautions to
ensure a stable, gas-tight contact with the
surfaces of the filter disc. As a result, the
path axial~y through the filter and then
along a channel between the filter disc and
~ the cover to the vent aperture or apertures
(or vice versa, first along a channel between
the filter disc and cover and then axially
through the filter) will offer much less resistance
than the path r~diall~ or obliquely through the
filter disc and there20re will be preferably
followed.
Another reason for the unsatisfactory Eunction
of the knowndevices must be sought in the
irregular production and composition of the
intesti.nal waste gases. If the absolute amount
of odoriferous substances to remove were
rather constant over the hours of the day,
the filter material, for instance active
carbon, cGuld be provided in an amount
corresponding to the xate of odoriferous gases
and the geometry of the placing of the active
carbon would be relatively unimportant. As,
however, amounts and compositi.on vary very
much, a regulax utilisation of the entire mass
of active carbon i.5 impossible and the geometry
of the device becom~s more important.
Obiect of the invention
It is an object of the invention to
overcome the disadvantages involved in the
channeling effect existing in known filters
for venting devices f.or stoma seals such as
stoma bags, stoma caps and stoma plugs, so
as to ensure that the gases do not pas.s
unpurified through the venting device
via nor~absorbing pa~ts thereof. Particularly,
is it an object of the invention to prov.ide
the filter in a forrn so as to give optimal
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' ', ' ' ~ :
utilisation of the active filter material
therein, i.e. of the odor-rernoving substances
whereby the geometric construction of the
filter will ensure that an amount of filter
material not greater than hitherto used will
be able to remove odoriferous gases from the
intestine gases even in periods with maximum
production of such gases with maximum contents
of malodorous components. It is a further
lo object of the invention to provide a filter
or venting device which will be equally well
adaptable to stoma pouches or bags, to stoma
caps and to stoma plugs or stoppers and
which can be manufactured as a releasable
member that can be uséd for a prolonged
period of tirne and be.transferred from one
stoma pouch, cap or pl.ug to another.
An important o~ject of the invention
is to provide a venting device including filter
which will be cheap and easy to make from
materials readily available. One important
further object of the invention is to provide
a filtering and venting device of the type
in question, which is reliable and will permit
the escape of no obnoxious gases from the
stoma or from a mal-func~tioniny anus, the gases
vented being free from a.ll malodorous
components.
; A further object is to provide a
filtering and venting device of the type
concerned which will avoid the condensation
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,.......... ......
of water vapours within the filter whereby its usefu:L lifetime
may be prolonged~
STATEMENT OF THE INVENTION
The invention concerns a device for ventiny discharge
openings from the human body, comprising in combination: -
a flat, platelet-like filter body of an odor-absorbing filter
material; a first cover adhesively bonded at one of its
surfaces substantially in the entirety thereof to one flat
surface of the filter body, the cover being made of a liquid
and gas-impervious sheet material and having substantially -the
- same shape and size as the filter body; a second cover
adhesively bonded at one of its surfaces substan-tially in the
entirety thereof to the other flat surface of the filter body,
the second cover being made of a liquid- and gas-impervious
sheet material and having substantially the same outer shape
and size as the filter body; the second cover is provided
with a substantially centrally placed opening defining a gas
inlet to the filter body; the edge of the filter body
constitutes a gas outle-t from -the filter body and is
uncovered.
In one preferred form of the device made in
accordance with the present invention, the filter body has
a substantially central opening aligned with the central
opening in the second cover so as to admit gas entrance to
the filter body via the inner edge formed at the central
opening thereof.
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DETAILED DESCRIPTION OF THE D:RAWINGS.
The venting devic~ according to the invention
will now be described mo~e in detail with reference to
the drawinys, it being un~erstood that drawings only
serve at illustrating the various principles involved as
represented by the various embodiments shown, and must
not be construed as a limitation of the invention.
In the drawing,
Fig. 1 is a cross section through the torso of a
person wearing a stoma pouch provided with one embodiment
~f the venting device according to the invention,
fig. 2 a part sec~ion through a person with a
stoma bag with another ernbodiment of the venting device
according to the invention,
fig~ 3 a part sec~ion through a third emhodiment
of a venting device according to the invention,
fig. 4 a section through a person and his stoma,
a plug inserted into the~stoma and provided with a
venting device according to the invention,
fig. 5 part of fig. 4 in larger scale,
figO 6 a cross section through part of ernbodiment
of the venting device according to the invention,
fig. 7 a cross section through part of a still
further embod~nent of the venting device according to
the in~ention,
fig. 8 a cross section through a plug for a stoma~
incorporating a venting device according to the in-
vention,
fig. 9 a longitudinal section of a stlll further
, .
embodiment of a ventlng device according to the invention,
fig. 10 a cross sectiorl through the embodiment of
fig~ g,
.
, :
Fig. 11 a longitudinal sec-tion through still another
embodiment of the venting device according to the invention,
Fig. 12 a cross-section through the embodiment of
Fig. 11,
Fig. 13 a flat view of part of a stoma bay provided
with a venting device according to the invention, and
Fig. 14 a cross-section through the bay and venting
device of Fig. 13.
Figs. 1-7 for reasons of clarity are shown as
slightly exploded views. In reality there will be no space
between, e.g., objects 1, 3~ ~ and 5.
As shown in Fig. 1, a stoma bay or pouch 6 is
fastened to the torso 1 of a person having a stoma 2, for
~` instance made by a surgical operation. A venting device
according to the invention is situated between the skin of the
patient and the bag. The venting device comprises a ring-
- shaped, gas-tight disc 3 of an adhesive polymer composition.
The disc has a central hole fitting more or less closely around
the outer opening of the stoma. One side of disc 3 adheres to
the skin of the person and thereby acts as a means or part of
the means for carrying the stoma bag. The other side of disc
adheres to a ring~shaped filter element 4 comprising an odor-
removing material~ Filter element 4 has a radial width a
number of times its thickness (in the embodiment shown about
20 times its thickness) and may for instance consist of a
; commercial filter paper impregnated with activa-ted carbon.
In a preferred embodiment, the ring-shaped filter element
is made of an open-celled, elastic cellular polymer foam
impregnated with or containiny activated carbon. On the
~o other flat surface of filter element 4 a further ring-
shaped, gas-tight disc of an adhesive polymer composition
~.~
is affixed; it bonds together filter element 4 and stoma
bag 6 the inlet opening of which is aligned with central
openings in adhesive rings 3 and 5 and filter element 4
as well as stoma 2 when situated in operative place. In
use, liquids and solids from stoma 2 can enter bay 6 via
the openings in ring-shaped elements 3, 4, and 5.
Intestine gases or gases evolved by the liquids and
solids can escape via the venting device; the~ enter the
ring-shaped filter element through the inner periphery,
pass radially through the filter element and leave through
the outer periphery. As ring-shaped discs 3 and 5 are
adhesive, there is ensured gas-tight contac-t between
them and the filter element, as well as gas-tight contact
to the skin of person 1 and to bag 6. Accordingly, the
gases can onl~ escape through the filter element; as this
filter element contains an odor-removing filter material,
and as its dimensions ensure a long path for the gases
through this filter material, it will effectively ensure
the removal of malodorous components of the gases whereby
only innocuous gases actually leave the device.
In fig. 1, the filtering element is situated
between the bag and the skin of the person. It might be
placed at the outer side of the bag 6, away from the
patient~s body. Thereby suitable means would be provided
to affix the bag direct to the body with its inlet aligning
the stoma; the opposite side of the bag would have an
opening aligning with the cerltral hole irl the filter
element 4, the latter being affixed to the bag. The outer
face of the filter eLement would be in gas-tight contact
with an entire disc of a gas-tight material e.g. a gas
tight plastic film, covering both the ring-shaped filter
element and the central opening thereof.
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,
However, the position shown in fig. 1 ls the most
advantageous because it has been found tha-t although the
intestine gases are saturated ~ith water vapour, no
condensation of water -vapour occurs inside the filter
element. Such condensation is difficult to avoid in a
filter placed at the outer, cooler surface of the stoma
bag and would, when formed, seriously interfere with
the function of the filter.
Although no special means are provided to prevent
liquid collected in the stoma bag from entering the
filter element, it has surprisingly been found that the
latter remains dry and active for long periods.
Nevertheless~ if the material collected in the bag
contains large amounts of water, or other special
conditions exist, it may be advantageous to use the
embodiment shown in fig. 2. Here, again, 1 is the torso
of a person with a stoma 2. Again, an inner ring-shaped
adhesive disc 3/ a r~ng-shaped filter disc 4 and an outer
ring-shaped adhesive disc 5 form a connection betwe~n
torso 1 and bag 6, the connection being gas-tight except
; for the possibillty of gases escaping through the odor-
removing filter material from inner edge to outer edge
of the disc. Here, however~ the inner edge of filter
element 4 is covered by a film 7 of a gas-permeable
hydrophobic material (e.g. the material sold by E i. du
Pont de Nemours and Company under the registered trade
mark "Tyvec")~ The "Tyvec" 7 is secured by yluelng or
welding to the inner part of the adhesive rings 3 and 5.
As actually shown, the stoma bag 6 ln ig. 2 is
adapted to be ~ecured to the fllter assembiy 3, 4, 5, 7
via flange 14. S~ch flange 1~ may be used to ensure
greated freedom of movement of ~he stoma bag. It may also
~r~J / ~
be used when the stoma bag is fastened to the torso by
means of a belt~ The embodiment of venting device shown
in fig. ~ may well be carried out without this flange 14~
. It will be understood that in use there is no space
between torso 1 and ring 3, between rings 3 and 4, or
between rings 4 and 5, or between ring 5 and either bag
6 (fig. 1) or flanye 14 ~fig. 2). A similar observation
will apply to the othe~ figures.
Fig. 3 shows a cross section of another embodiment
of a filter for use under conditions of large amount of
water in the bag, or other special conditions. Reference
numerals 3, 4 and 5 have the same meanings as in fig. 1
and 2 and 8 is an inner riny of a gas-permeable
hydrophobic material such as "Tyvec" (trademark) or of an
open-celled h,vdrophobic foam plastic.
Fig. 4 is a cross section in the torso 1 of a
patient with a stoma 2 closed by a so-called magnetic
- plug 11. By a surgical operation a permanent magnet in
the form of a riny enclosed in a suitable plastic material
12 has been placed around stoma 2. This ring attracts
and holds the plug 11 which contains another magnet or
set of magnets (not shown). By the attractive forces
between the magnet(s) in 12 and 11, a cover plate 10,
which is part of plug llp is pressed against a gasket 9
which prevents leakage from the stoma. With this type of
closure for the stoma the build up o pressure ~rom
intestine gas collected in the stoma is a particularly
severe problem. The gas pressure lifts the plug away from
the gasket even if the yasket is adhesive, and leakage
results. For this type of stoma closure our invention
is particularly useful.
Fig. 5 shows a detailed half cross-section of
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.. ... .. . . .
¢~
gasket 9 which is made according to our invention and
comprises a filter allowing the intestine gases to
leave the stoma without ~scharging malodorous gases to
the free. A ring-shaped inner disc 3 of gas-impervious
material is adapted to bé held in gas-tight contact with
the skin under the influence of the magnetic forces. Ring
3 is in gas-tight contact with a ring-shaped filter disc
4, e.g. of similar const~uction as disc used in connection
with figs. 1 and 2, and thus again in gas-tight contact
with an outer gas-impervious disc 13 which is made of
adhesive material or provided with an adhesive on both
sidesO
The radial width of yasket 9 is at least 5 times
the thickness of filter ring 4. Disc 13 is not absolutely
necessary as cover plate 10 may itself act as the gas-
impervious cover. It is, however, an advantage to use the
adhesive disc 13 which positions and keeps the filtre
disc in place when the plug is opened and closed for
removal of faecal material.
Ring 3 may be a so~t flexible gasket and if desired
may also be adhesive to obtain maximum security against
leakage.
Fig. 6 shows a cross-section of another gasket
suitable for use with the magnetic plug 10, 11. Reference
numerals 3, 4, and 13 hav~ the same meaning as in fig. 5.
Reference 7 is a ring of ';Tyvec" (trademark) which extends
over the inner edge of the filter disc 4. This disc oE
"Tyvec" (trademark) or other hydrophobic gas-permeable
- material must have an outer diameter smaller than the
filter disc; the radial distance from its outer periphery
to the outer periphery of the filter ring must be at
least 5 times the thickness of the filter discs. It
goes without saying that there must be gas-tight contact
- 17 -
must be gas-tight contact between filter ring 4 and ring 3
where the "Tyvec" (trademark) ring 7 is not pxe~ent.
Fig. 7 shows a cross-section of another filtre
assembly suitable for use both with a magnetic plug and
a stoma bag. Here one of the gas-impervious covers (3)
has a larger central opening than filtre ele~ent 4,
thereby increasing the effective area through which the
gas may enter the interior of the filtre element. Again,
the three rings must be in gas-tight contact with each
other and the radial width of the cover ring (3) having
the larger central opening must be at least 5 times the
thickness of the filter ring.
If desired the filter element may be impregnated
partly or wholly with a hydrophobiny agent such as a
fluorpolymer or a silicone.
It is also understood that if desired the filtre
need not be symmetric with respect to dimensions or other
properties around the stoma, but may for instance be
gas-impervious around a fraction of the stoma periphery.
Fig. 8 shows a section of a plug 11 somewhat like
that shown in fig. 4. It is held in the stoma 2 of a
patient 1 by magnetic means placed partially as a strong
permanent magnet ring 12 situated under the skin of the
patient around the stoma, partially placed in the plug
which contains several strong magnets rnoulded into a co~non
housing o~ a suitable plastic 10~ Be-tween the plug and
the skin, iOe. at the inner surPace of a Plange-like
extension or cover plate 10, there is a sealin~ gasket 9 o~
.
a soft material. In the plug proper there is a longi-tudinal
channel extending from the inner end of the plug to the
top or flange 10 which is integral with the plug proper.
In this top ther~ is a cavity or rece3s in which there is
~; .
inserted a venting device in 'che ~orm of a capsule 17.
Expediently there is a pl~te 13 of erro-magnetic m~terial
moulded into the base of the venting device; this will
ensure that the venting ~evice is held in place by the
strong magnets inside th~ plug and ye-t allow easy
replacement when exhausted. The venting device 17 may
also be held in place by a self adhesive coating a by a
- snap lock.
Figs. 9-10 show a very convenient venting device
for use as device 17 in ~he plug shown in fig~ 8.
Here 21 is a flat cylindrical box or capsule having
a hole 22 in the bottom ~hrough which the intestine gas
may enter the interior o~ the box, e.g. via the channel
in plug 11. The hole is ~overed with a relatively coarse
filter 23 which prevents the intrusion of solid material
from the stoma and the escape of absorbing media from the
; box. The box has a dividing member or partition 24 moulded
to the bottom thereof an~ extending up to covering lid 25
and forming a spiral path from the entry hole 22 to the
exit hole 26 in the lid. ~7 is a so~t material which
provides a gas tight seal between the dividing member
and the lid thereby forcing the intestine gas to follow
the long spiral pa~h. The interior of the box is filled
with one of the odor-removing materials 28 described.
29 is a self--adhesive rnaterial which allows the patient
to affix the filtering d~vice to the stoma seal or stoma
bag and may replace plate 18~ The length of the spirally
coiled channel is at least 5 times the square root of
its cros~ sectional area !
In ~igs~ 9-10 the ~ntry opening 22 for the gases
is placed near the periphery and the exit hole 26
.~ centrally; ackually, the opposite positions is more
.~ 5~
suitable when using this form of a venting device in a
plug as shown in fiy. 8 whereas the positions actually
shown are convenient when using such form of venting
device in connection with a stoma bag.
Another embodiment of a venting device according
to the invention and suitable especially for a stoma bag
is shown in figs. 11 and 12. Again, the venting devices
consists of a flat box or capsule (which in this embodiment
is preferably rectangular or even square) having an entry
opening 22 for intestine gases in the bottom and an
exit opening 26 for purified (deodorized) intestine gases
in the top or lid. The box is filled with an odox~
removing filter material 28 and this is effectively in the
form of a long channel (at least 5 times its smallest
dimension) formed by the aid of several vertical
partitions each extending from upper or lower side wall
o~ the box to a position near the opposite wall so as to
form a zig-zay or wavy channel. The vertical orientation
of the partitions is preferred (it is observed in this
connection that "vertical" refers to the position in use
when the patient is sitting, standing or going; the
"bottom" and "lid" refers to the larger surfaces of the
box; the "bottom" in use is nearest the skin and the
"lid" turned away therefrom). The advantage of the
vertical ori~ntation of the partitions is that gravity
will drag the filter material 28, if it i5 granular,
towards the lower parts of the box and completely ensure
filling of the channels an counteract channeling.
Filter material 28 is held in gas-tight contact
with lid 25 by soft material 27. Self-adhesive material
29 permits the box to be affixed to a stoma bag.
It is preferred that the channel through ~Jhich
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.
$
the gases must pass is filled with filter material 28,
from the side and not from one end, especially if it is
granular.
In the preferred embodiment this is obtained by
n~king the housing of the filtering device in two parts,
one comprising the bottomj the outer walls, and the
dividing members forming ~he channel, and the other being
in the form of a lid which closes the channels.
Filling material is poured into the open box, and
excess material is removed by a doctor blade before the
lld is put on. This methad of filling is - par-ticularly
in the case of complicated patterns - much simpler and
more efficient than any other method.
It has been found that by making the filter in the
form of a flat container which is used with the flat
dimension parallel to the skin of the patient, the
deodoriæing filling material remains dry and active
over a long period of timeO This is in contrast to other
designs where condensation of water vapour takes place,
and the condensed water rapidly reduces the effectiveness
of the filter. A possible explanation may be that the
design according to the invention ensures maximum contac~
with the patient's skin and gives substantially body
temperature in all parts of the filter.
In a preferred embodiment the filtering device
is affixed to the upper part of a stoma bag.
An embodiment especially preferred for use with
certain stoma bags is shown in fig. 13 and fig. 14. Here
31 is a flat plastic ~ilm which is part of a stoma bag.
In the upper part there is a venting device 32 comprising
a carrier impregnated with the odor-removing filter
material, and comprising a flexible member 33 which may
~ 2]
be in the fo~n of a flat strip as shown in fig. 13 or
in another suitable form, for instane in the form of
a core placed in the center of the filter. The filter
is closed by a profiled or grooved sheet of plastic film
34 placed on top of bag 31 and sealed to it preferably
under slight compression of the flexible member. This
compression of the flexible mem~er will assure that in
use the filter is pressed against the walls whereby
channeling (- the passage of gases in voids along the
walls in insufficient contact with the filter) is
effectively prevented. The groove may, for instance,
have the shape shown in fig. 14.
A filter of the same general shape as that shown
in fig. 13 and fig. 14 may also be made by heat sealing
the two films forming the external walls but leaving the
top end unsealed. A filtering material is then filled
into the parallel channels, to ease the filling these
may for example ~e kept open by applying a slight vacuum
to the external walls. After the channels are filled they
are closed and interconnected by heat-sealing of the top.
Exam~le 1
A stoma bag made from polyvinylidene chl~ride and
having a flange on the r~ar side was fitted with a
filter element of the general construction shown in fig. 2
The active fi]-ter element (~ was made from 3 mm thick
opencelled polyurethane foam of density 17 kg/m3
impregnated with a slurry of activated carbon powder in
a binder compxising an ethylene-vinylacetate polymer
dispersion. The impregnated polyurethane foarn had a
density of 48 kg/m and contained 37% b.w. of activated
carbon.
The ring-shaped gas-tight discs (3) and (5) were
made from a double sided self~adhesive polymer composition
which adhered firmly to the filter element (4) and this
prevented channeling.
The stoma bag wastested on a male patient having severe
problems with large volumes of intestine gas. The bag was
used over 28 hours and during this time the intestine gas
was released continously and was completely free of odor.
When using a stoma bag with a filter device according to
USP 3,759.260 the patient complained that the venting device
was not able to deodorise the intestine gas as fast as it
was produced and he had to change back to a venting device
according to the invention.
Example 2
A patient having a stoma closed by a magnetic plug as
shown in fig~ 4 complains o~ leakage around the plug. Various
gasket materials and known gaskets constructions are tried,
but the seal is never tight for more than a short period,
after which time faecal rnaterial starts toleak out. The
magnetic plug is now fitted with a filter device oE a
.
.J~ .
construction as shown in fig. 7. The actlve filter elernent
is made from an opencelled flexible polyurethane foam
impregnated with activa-ted carbon. The overall densi,ty is
60 kg/m3 and the filter contains 29% b.w. of carbon.
The outer gas-tight disc (13) is made from a double-sided
self-adhesive polymer composition and the inner yas-tight
disc is made from a sealing material comprising about 50%
of a viscous polyisobutylene matrix and about 50% of a
hydrophilic powdery filter comprising gelatin, sodium carboxy-
methyl cellulose and powdery pectin . The outer diameter of the
filter device is 60 millimeters and the diameter of the
central hole in ring (4) and adhesive disc ~13) is 10 mm
and in the inner cover (3) the hole diameter is 14 mm.
With this filter device the plug remains tight for
82 hours. The intestine gas is completely deodorized and
lS vented as fast as it is produced and there is no leakage
of feacal material. ~he plug is opened three times during
this period and faecal material is removed by irrigation
of the intestine. When the plug is reinserted the seal is
still perfect.
Example 3.
In an investigation at the University Clinic at Erlangen,
Germany, nine stoma patients, who all had severe problems
with leakage of obnoxious material around their magnetic
stoma plugs when using known gaskets were given venting
devices according to the invention. With a venting
device as shown in fig. 7, eight of the nine patients became
free of problems, i.e., the intestine gas was removed in
a controlled manner through the filter and there was no
problem with leakage or odour.
In a slmliar investigation made by Dr. H. Feustel at
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the University Clinic at Giessen, Gerrnany, nine out of ten
patients were relieved of problems with their stoma.
Example 4
A magnetic stoma plug was fitted with a venting device
of the construction shown in fig. 6. The filter elernent (4)
was made from filter paper impregnat0d with active carbon.
The outer gas-impervious disc t13) was made from a
styrene-isoprene-styrene rubbex sheet, and the inner disc
(3) was made from sealing material comprising a viscous
polyisobutylene matrix wi~h a hydrophili filter comprising
a blend of starch~ gelatin and pectin. The gas~tiyht contac-t
between disc (13) and the fil~er element (4) was obtained
by the magnetic forces holdiny the plug in place in the
stoma. This plug was tested on a patient who had never
been free of leakage and odours from his stoma. With the new
venting device he had no problems with leakage and the
intestine gas leaving the filter element was completely free
of odour. After 29 hours the plug was removed. The filter
element was still active 9 but the inner gas-impervious disc
(3) had swollen so much from intestine fluids that the
passage between the inner rim of the disc and the plug (11
in fig. 4) was blocked. The function of this v~nting device
could ba further improved hy incr~asing the diameter of
the central hole of disc (3~ as shown in fig. 7. The
ratio between thickness of filter element and radial path
from the centxal hole to the outer rim wa~ in this
experiment 1.40.
. .
_ ample 5
In order to investig~te the in1uence of the physical
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dimensions upon the performance of the active filter element
the following experiment was made.
A flexible open-celled polyurethane foam was cut into
sheets of a thickness of 3 mm. The sheets were impregnated
with active carbon in a binder comprising a vinyl copolymer
dispersion. The dried sheets contained 28% b.w. of carbon
and had a density of 55 kg/m .
- Rectangular discs were cut from a sheet. The area of
the discs were in all cases 4,5 cm and the lenyth and width
lQ were as shown in table 1. These discs were each covered with
adhesive gas impervious tape on top, bottom and the two
sides, whereas the remaining two sides were sealed to
small plastic tubes to allow the passage of gas through the
inlet tube into the disc through its lengthwise direction,
and then out through the exit tube. The inlet tube could
be connected to a gas tank filled with a test gas at
atmospheric pressure. The exit tube could be connected to
a detector tube containing a plumbous salt and calibrated
to show the amount of H2S in the gas passing the tube. The
other end of the detector tube was connected to a calibrated
suction pump which could pump precisely known volumes of test
gas from the gas tank, through the filter el ment and the
detector tube. The test gas consisted of a blend oi 80~ nitrogen
and about 20% methane with 25 p.p.m. N2S added. During the
experiment any H2S not being absorbed by the filter
element would react with the plumbous salt in the detector
tube from which a direct reading of the amount could be
obtained.
Since in practice the stoma patients have the greatest
pro~lems when large volumes of intestine gas is suddenly re-
leased the gas rates were varied to find the filter dimensions
most effective at the high gas rates corresponding to this
situation.
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.
Table 1. DiMensions of Filter Elements
Filter No. Length Width Thickness Length
mm mm mm Thickness
_ ~
1 322.4 22.4 0.1
2 _ 10_ _ 15 1.1 _1 :
3 15 30 3 5
4 ~ 30 15 10 -
_
1~ 3 15
Table 2. Efficiency of Filter Elements versus Flow Rate
_
Rate ~lf/mian. 10 20 50 100 200
: Filter Total Effi- Effi- Effi- Effi- Effi-
No. vol. ml. cieney eieney eieney eieney ciency
% % % ~ %
: 100 9890 77 60 20
20~ 25
-: : 1 300 9784 66 47 27
400 30 .
500 9569 55 44 32
_ _ ' ",
100 9994 91 80 58 -
2 300 9992 78 59 42 ~. :
500 9885 70 55 40
.......
100 100100 96 89 60
200 100100 92 80 55
3 300 100g8 84 70 50
400 10098 79 67 45
500 10096 78 67 44
_
100 100100 100 96 80
200 100100 100 90 70
. 4 300 100100 93 83 60
400 100100 90 77 56
. 500 10099 89 72 52
. _
: 100 100100 100 100 86
200 100100 100 91 70
300 100100 98 83 65
~00 100100 90 77 55
~ 500 10099 _ 90 72 55
.' :
-~
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.
~3~
The results of the experiment are shown in table 2.
It will be seen that filter No. 1, where the gas passes
perpendicularly to the plane of the filter element is the least
efficient. Even at the lowest gas flo~ rate 100% efficiency
is never reached and as the flow rate increases the efficiency
drops rapidly. ~Efficiency is the percentaye of H2S
absorbed by the filter).
The filters Nos. 3, 4j and 5 are all highly efficient
at the lower flow rates even after a total of 500 ml of
test gas has passed the filter elements. At higher flow
rates the filters drop off in efficiency, but even at
a rate of 100 ml/min filters Nos. 4 and 5 retain an efficiency
of 83% after the first 300 ml of test gas and 72 % after
500 ml.
Filter No. 2 is, although clearly better than No. 1,
never 100% efficient and is more sensitive to an increase in
flow rate and volume than filters 3, 4, and 5.
It is thus seen that in order to combine efficiency at
high flow rates with large total capacity the venting device
should be designed with a gas path through the filter element
which is considerably longer (at least 5 times) than the
sma~estdimension of the filter element.
Example 6
A test gas comprising nitrogen, methane, hydrogen ,
carbondioxide and 25 p.p.m. H2S was passed into a commercial
stoma cap manufactured by 'iHollister Incorporated" and
basicly described in Danish Patent Specification No. 133080.
The gases leaving the exit hole in the venting device were
passed through a detector tube and the total amount of ~l2S
passing the venting device was measured. After 400 ml of
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"
test gas had passsed a re~ding of 5 was obtained. After
600 ml the reading had incx~ased to 15 and th~ experiment
was stopped. In a similar stoma cap the fil-ter element
was brought into gas-tight contact with enclosing gas-tight
plastic foils by the use of an adhesive, so that the gas
had to pass from the rim 'co the venting hole through the
filter element and channeling waseffectively prevented.
Test gas was now passed through the venting device. After
400 ml the reading was zero. After 600 ml the reading
was 7.5 and the experiment was stopped.
Example 7
A stoma bag made from two rectangular sheets
of plastic foil sealed around the edges is fitted with a
venting device consisting of flat filter element measuring
15 x 30 x 3 mm made from elted cellulosic fibers and
containing finely granulated active carbon. The filter
element is placed into a small pockat made by sealing of a
22 x 40 mm sheet of a similar plastic foil onto one of
the sheets forming the stoma bag. An entry hole and an
exit hole i5 made in the two sheets enclosing the filter
element so that the gas to be vented is forced to pass
through the length of the filter element.
In anothex stoma bag of a similax construction a gas-
tight contact between the filter element and the enclosing
walls is obtain d by means of an adhesive.
The capacity and efficiency o~ the two v~nting devices
is compared by passing a test gas containing H2S through
them. The results are shown in table 3.
,
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. .
Table 3
Vol~ ~n 1 Efficiency
of Test without gas-tight contact with yas-tight contact
Gas 50 ml/min100 ml/min 50 ml/min100 ml/min
. ,
100 100 100 100 100
200 l00 90 100 96
300 93 66 95 8~
400 83 53 92 80
500 66 52 _ 89 72
The results clearly show that efficiency can be
considerably improved by bringing the filter element into
gas-tight contact with the enclosing walls.
Example 8
In another experiment the venting device described in
the above example was fitted onto a stoma bag by an
self-adhesive disc ((29) in fig. 10)~ so that intestine gases
collected in the bag could be vented through the venting
device into the a~nosphere~ In use the stoma bag would collect
the solid and liquid faecal material produced in the intestine
while the intestine gas was deodorized and released through
the venting device. After a period of the normally 5~10 hours
the bag with the collected material would be removed and
discharged, while the venting device was transferred onto a
new bag, which was placed over -the stoma. After three weeks
o continous use in this manner the venting device still
performed satisfactory and the patient had no problems
with odours.
Exa~
A venting device as shown in fig. 9 and 10 is fitted
.` ,. . -- A--~ --
3~
into a magnetic plug as shown in fig. 8. The venting device
comprises a flat cylindrical box or capsule moulded
from a thermoplastic polymer and having the following
dimensions in millimeters: outer diameter: 23, inner
diameter. 19.2, height of inner compartment: 4.0, length
of path from inlet hole (22) to outlet hole (26): 100.
(Note that in this example the entryhole is placed in the
bot~om at the center, while th exit hole is placed in the
lid(25) near the periphery). Average width of ~piral path:
approximately 3 mm. The capsule is filled with granular
activated carbon and a substantially gas-tight seal is formed
between the walls of the capsule and the act~vated carbon by
the use of a flexible material (27) which in this case is
a flexible cellular polyurethane.
The magnetic plug with the venting device is tested
for a week on a patient complaining of large volumes of
odorous intestine gas. The filter element gave excellent
performance and the patient had no problems with ordours
during the entire test period.
.
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