Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a fixing system for
fastening cannulas, catheters and the like to the skin, as
well as to a process for the sterile fastening of a cannula
to the skin.
The terms "cannula" and "catheter" are intended
herein to mean "probes" of the type used e.g. for
introducing body fluids into vessels and removing body
fluids from vessels, and can be in the form of needles,
cannulas, catheters, measurement probes (e.g. for measuring
lO certain body parameters, such as the oxygen partial
pressure), as well as infusion means. Cannulas must be
secured to the body, e.g. during the dialysis of patients
or during longer infusions. Means for fixing cannulas and
catheters are known.
EP-B1-76 896 and EP-Al-121 679 disclose a medical
dressing for fixing a probe, having a dressing portion
which can be fastened to the skin and to the part of the
probe projecting from the skin by means of plasters. This
dressing portion is provided with a tubular extension,
20 which serves as a support or reception means for the probe
part projecting from the skin.
German Utility Model 82 04 827.4 describes a
holding or retaining device comprising two clamping plates,
which receive a cannula which is then secured by plaster to
25 the skin.
DE-OS 32 12 458 discloses a bandage system for
catheters to be externally applied to males and more
particularly ~relates to the geometrical configuration of
plaster strips.
German Patent DE-PS 29 47 427 relates to a vein
catheter bandage which, by means of a plaster with a
watertight, air-permeable, contact adhesively finished
film, which can optionally have a moisture-absorbent layer
on the skin-remote side, and fixes a cannula with a stop
35 valve to the skin. Dimensions of 95 x 60 mm are given as
the preferred dimensions for the plaster.
~ DE-OS 31 05 187 describes a cannula fixing
;~ plaster with a punched out plaster segmant which, upon
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insertion of the cannula, is fixed to the latter and in
this way prevents the removal of the cannula, whilst the
remaining plaster adheres to the skin.
EP-Al~116 526 relates to another principle for
5 fastening cannulas to the skin, in which a catheter
retaining device is fixed by means of a needle passed
through the skin of the patient to be treated. In special
cases the catheter is even sewn to the skin for securing it
in position.
For example, under the trade mark POROFIX,
plaster strips are commercially available for fixing such
cannulas. They are adhesive plasters with a slit, which is
in particular used for fixing ~trauss cannulas during
infusions.
These known cannula fixing plasters have the
advantage that the underlying skin portions can breath, the
film being water vapour and oxygen permeable, so that there
will be no maceration of the skin surface.
However, it is a disadvantage of the known
20 cannula fixing means, that the insertion or puncture point
and the underlying skin portions in the puncture or
insertion channel are not adequately protected against
infections from bacteria which can enter from the skin
surface. Attempts have been made to at least partially
25 obviate this problem by disinfecting the skin prior to
puncturing. However, disinfection only treats the upper
skin layers and is unable to prevent the penetration of
bacteria into the insertion channel from lower lying skin
layers or from the exterior.
It is important to ensure a good fixing of the
cannula, so as to prevent slipping thereof over long
periods of time.
The prior art arrangements only partly solve this
problem. it is necessary to use either very complicated
35 means for fixing the cannula, which is stuck to the skin
with the adhesive plaster, or simple plasters with
-`~ incisions or slits, which do not lead to a satisfactory,
long-term cannula fixing.
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An object of the present invention is thus to
pro~ride an improved cannula fixing system, which protects
the insertion or puncture point against infection, even in
the case of cannulas which are left in for long durations,
5 such as shunts in the case of dialysis patients, and is
accompanied by good fixing, and simultaneously preventing
damage to the skin layers.
Accordingly, one aspect of the invention provides
a fixing system for fastening catheters and cannulas, which
10 comprises a skin film coated with a skin adhesion layer and
having a cover film and an overplaster finished with a
contact adhesive layer adhering to the skin film and having
an overplaster cover layer.
Another aspect of the invention provides a
15 process for the sterile fastening of a cannula to the skin,
which comprises applying a bacteria-tight skin film with
skin adhesion layer to the skin in the cannula insertion or
puncture region, passing the cannula through the skin film,
applying to the area of the underplaster surrounding the
20 insertion point an adhesive forminq an elastic, bacteria-
tight film adhering to the underplaster with at least part
of the cannula portion projecting from the skin, so that
the puncture region is sealed, and then sticking the
overplaster over the cannula.
In a preferred embodiment of the invention, the
layers are superimposed in sandwich-like manner and on one
side are interconnected in a partial region without an
intermediate film or an intermediate separating film, the
overplaster cover layer becoming an intermediate separating
30 film between the skin film and the contact adhesive coating
of the overplaster.
It is also advantageous if the skin film is a
flexible, water vapour-permeable and bacteria tight film,
e.g. a natural or synthetic polymer, such as cross-linked
35 collagen or polyurethane, such as is commercially available
in incision film form. The skin film and/or overplaster,
as well as optionally also the contact adhesive layers can
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be transparent, so as to permit observation of the
insertion or puncture point.
If both the overplaster and skin film are
transparent, it is possible, even in the case of a longer-
5 term fixing of a cannula or catheter, to constantly checkthe position thereof by inspecting the outside of the
cannula fixing system, without it being necessary to remove
or open the latter, which would give rise to infection or
injury risks for the patient. As a result of this
10 advantageous construction, it is possible in many cases to
obviate cannula changes.
If the surface of the skin film is larger than
the overplaster, a very good adhesion of the skin film to
the skin is ensured as a result of the larger adhesive
15 surface and it is now possible to adhere to the skin film
an overplaster with a very strong adhesive in the contact
adhesive coating, which might even lead to skin layer
injuries if it were to be used on the skin. It is
appropriate for the ovarplaster to have a much smaller area
20 than the underplaster, so as to prevent any maceration of
the skin by air and moisture exclusion when using an
overplaster with poor air and moisture conduction.
It is advantageous in this case if the contact
adhesive layer of the overplaster more strongly adheres to
25 the skin film than the skin adhesion layer adheres to the
skin. Preferably the overplaster cover film has a
separating line and optionally two removal aids for each
intermediate separating film portion.
According to a preferred embodiment of the
30 invention, the skin film can be coated with an active
substance on one or both sides and preferably with a
bactericidal substance or the like. To prevent detachment
of the edges of the skin film from the skin, in addition to
the skin adhesion layer, the s~in film can have an all-
35 round, more strongly contact adhering adhesive rim orborder.
The overplaster can be perforated, so as to
ensure that, in the case of any necessary application of a
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solvent to the overplaster, it is possible to ensure an
easy removal thereof by neutralizing the adhesive layer by
the solvent. Following such solvent treatment, it is
possible to remove the upper plaster and then the cannula.
5 The skin film can then be removed. The perforations also
prevent maceration of underlying skin surfaces.
A particularly preferred embodiment of the
inventive fixing system also includes an adhesive forming
elastic polymer or its starting material, which adheres to
10 the skin surface and the cannula surface and, following
application to the skin film and insertion point, forms a
bacteria-tight sealing of the insertion point together with
the skin film.
According to another embodiment of the invention,
15 the inventiva fixing system can also include a cannula
support body and a reception opening adapted to the outside
shape of a cannula, in such a way that, when the cannula
support body is applied to the skin film, the cannula is
fixed at a predetermined angular position in the reception
20 opening. The cannula support body can optionally also have
a contact adhesively finished support surface, with which
it is engaged on the skin ~ilm and can, for example, be
~ixed during the insertion o~ the cannula. This embodiment
is particularly advantageous if it: is intended to avoid
25 firm adhesion of the overplaster to the cannula, which
could in certain circumstances be painful for the patient
on removing the cannula. In this case the cannula is
fastened by frictional engagement in the reception opening
of the cannula support body.
The cannula support body is advantageously
moulded from elastic material, preferably a polymer, which
is optionally transparent. Silicon rubber or other
polymers are suitable for this purpose.
As mentioned above, the invention also relates to
35 a process for the sterile fastening of a cannula to the
skin, characterised by the application to the skin in the
puncture or insertion region of the cannula of a bacteria-
tight skin film with skin adhesion layer, passing the
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cannula through the skin film, applying to the skin an
adhesive forming an elastic, bacteria-tight film adhering
to the underplaster in the cannula insertion region,
passing the cannula through the skin film, applying to the
5 area of the underplaster surrounding the insertion point an
adhesive forming an elastic, bacteria-tight film adhering
to the underplaster and to at least part of the cannula
portion projecting from the skin and sticking the
overplaster over the cannula.
In a preferred embodiment of the inventive
process a cannula support body is engaged and fixed on the
skin film or skin, with subsequent or prior embedding of
the cannula in the reception opening of the cannula support
body.
The cannula support body can be fixed in position
both by means of a contact adhesive layer, by means of an
adhesive or by sticking over with the overplaster.
In a preferred embodiment of the inventive fixing
system with two separate plasters comprising cover film,
20 skin adhesion layer and skin film, together with an
overplaster cover film, contact adhesive layer and
overplaster, the skin film, which is preferably an incision
film, is detached from its surface cover layer and adhered
to the skin surface to be provided with a cannula. The
25 incision film is then perforated by the cannula. The
punching out of an incision film portion by the hypodermic
needle and the feeding of the same into the insertion or
puncture channel can be obviated either by choosing a
suitable semi-blunt cannula form, so that only a horseshoe-
30 shaped tab is punched out and continues to be connected ~othe ~ilm on one side, or by using an incision film (e.g.
cross~linked collagen~. Another advantageous alternative
involves the use of a cannula with a retractable central
pin. Basy cleaning is made possible in that, prior to the
35 introduction of liquids into the body, the inside of the
cannula is cleaned, e.g. by producing a vasuum on the body-
remote side, for sucking up of residues of punched out
portions and also any detached tissue parts.
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A particularly preferred embodiment with active
ingredient-filled incision film is particularly
advantageous if the inventive cannula fixing plast~r is
in-tended to be left on the skin for a long time. The same
5 also applies in the case of patients for which an infection
would have a particularly negative effect, because a
cannula is frequently introduced into their vessell e.g. in
the case of dialysis patients. In such cases a so-called
shunt is produced, i.e. a connection between an artery and
10 a vein, and then a new cannula can be inserted there for
each dialysis. ~n incision film coated with bactericidally
active substances on the top of th~ skin film, in addition
or alternatively thereto, would substantially prevent a
migration of bacteria towards the body-remote puncture
15 point.
According to a particularly preferred embodiment
of the inventive fixing plaster, the overplaster portion
and skin film portion, separated by an intermediate
separating film which is optionally adhesive on both sides,
20 are superimposed. It is preferable for the intermediate
separating film to have a separating line, which defines a
larger and a smaller surface portion. It is appropriate
for the removable intermediate separating film parts and
cover films to have removal aids.
Firstly the cover film covering the skin film on
the skin side is removed (optionally using a removal aid)
and the remaining sandwich-like plaster system is adhered
as an entity to the skin. Subsequently, part or all the
overplaster is drawn off from the skin film together with
30 the intermediate separating film. A portion of the
intermediate separating film is detached from the
separating intermediate film residue along a prepared
separating line and then detached from the overplaster.
The now exposed contact adhesive layer is adhered to the
35 skin film. The remainder of the intermediate separating
film is now flapped away from the skin film, together with
the overplaster part covered but not adhered by it, so that
the skin film, preferably an incision film is located
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freely over the puncture point. This step is then followed
by puncturing. The intermediate separating film is now
completely removed, optionally with a second removal aid
and the overplaster is placed over the cannula, so that it
5 rests in roughly horseshoe-shaped manner on the lower
plaster and the cannula projects from the open side of the
horseshoe. (Obviously the sequence of steps can be
modified, e.g. the cannula can be engaged ~irst followed by
the overplaster being stuck down).
To avoid maceration phenomena and in order to
facilitate removal of the overplaster by solvents, it may
be appropriate to perforate the overplaster.
With the aid of the inventive cannula fixing
plaster, the cannula can be supported in a pocket formed by
15 the skin film and overplaster and consequently contact
between cannula and skin is substantially avoided.
To avoid punching out a skin film portion on
inserting the cannula, the latter can be engaged on one
edge, or even outside the fixing system, so that improved
20 fixing of the cannula is made possible by the inventive
fixing system. There is no complete coverir.g of the
insertion region by the skin film and use is made solely of
the fixing action of the fixing plaster system.
The individual parts of the fixing system, such
25 as the underplaster, overplaster, and adhesive matched
thereto and the cannula support body are essential to the
invention.
Emhodiments of the invention will now be
described in greater detail with reference to the
30 accompanying drawings, in which:
Figure 1 shows an embodiment of fixing plaster
with separate overplaster and skin film;
Figure 2 is a longitudinal section through a
sandwich-like overplaster - skin film combination;
Figure 3 is a plan view of the plaster o~ Figure
2 in the fitted state;
Figure 4 shows the plaster of Figures 2 and 3
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prior to the application of the overplaster and with
adhesive applied;
Figure 5 is a plan view of an overplaster - cover
layer combination with removal aid and separating line;
Figure 6 is a view of an embodiment of the
inventive fixing system with cannula support body; and
Figure 7 shows a cross-section of the fixing
system of Figure 6 taken along line VIl-VII' of Figure 6.
Referring now to the drawings, as ~hown in Figure
10 l, a preferred embodiment of the inventive "underplaster"
comprises a cover film 1, a skin adhesion layer 2 and a
skin film 3, which is preferably finished in an air and
water vapour-permeable and optionally also bactericidal
manner. The "upper part" of the fixing system comprises an
15 overplaster 6, a contact adhesive layer 5 and an
overplaster cover film 4, optionally with a removal aid.
The fixing system shown in Figure 1 is able to fix a
cannula 8 (Figure 3) which, follow:ing the adhesion of the
skin film to the skin, is optionally sealed with a
20 bacteria-tight adhesive 7 and is subsequently fastened by
the overplaster 6 stuck to the skin film 3.
Figure 2 shows a sandwich-like variant of the
inventive fixing system, in which the same layers as
described in Figure l are superimposed, but in this case
25 the overplaster cover layer 4 constitutes an intermediate
separating film.
Figure 3 shows the plaster shown in Figure 2
applied to the skin. A smaller overplaster 6 is stuck to a
large surface skin film 3 and fixes the cannula 8 in
30 position.
In Figure 4 the cannula 8 has already perforated
the secured skin film and the overplaster with a portion
freed from the intermediate separating film stuck to the
skin film 3. The bacteria-tight adhesive 7 has been
35 applied around the insertion point on the skin film 3 and
the free cannula end, whilst forming a foil-like seal. The
overplaster portion 3 still provided with the intermediate
separating film 4 is flapped back and has on its end a
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removal aid, which facilitates the removal of the remaining
intermediats film portion. The next operation is to remove
the intermediate separating film 4 from the remainder of
overplaster 6 by means o~ the removal aid, to place the
5 overplaster 6 over the cannula 8 and to secure same by
adhesion.
Figure S shows the surface portion of Figure 4
from the side of the intermediate separating film 3. It is
possible to see two removal aids and a separating line,
10 along which initially a part of the intermediate separating
film is removed and then the overplaster 6 is stuck to the
skin film 3.
Figure 6 shows a further development of the
inventive fixing system, in which a cannula support body 9
15 formed from an elastic polymer is adhered to the skin film
3 with a support surface 10, which in this embodiment has a
contact adhesive finish. The cannula support body 9 has a
reception opening 11, in which the cannula 8 can be
frictionally engaged. In the embodiment shown, the cannula
20 8 can be pressed through a slit in an elastic boundary wall
of the reception opening 11 and is secured by the cannula
support body walls which elastically return to their
inoperative position.
Figure 7 shows sectionally the fixing system of
25 Figure 6 taken along line VII-VII'. For a better fastening
of the cannula 8, an overplaster 6 is adhered over the
cannula support body 9. In this embodiment there is no
need for a contact adhesive coating of the skin support
surface 10.
