Mounting platform for skin piercing medical devices
Many treatments and diagnostic procedures rely on the placement of drugs or devices in the subcutaneous tissue. A prime example is injections with insulin which should be made sub- cutaneous. Also devices like electrochemical sensors or micro dialysis tubing for measuring the level of metabolites in the blood or tissue liquids have to be passed through the skin thus placing the active part of the device in a sub-dermal position.
Often these devices have to be coupled to an external device using wires or tubes. Thus, use of this type of device requires a semi-permanent penetration of the skin. This type of devices is in the following referred to as trans-dermal devices. This text refers to an improved method for mounting trans-dermal devices.
Transdermal devices which have to remain in a subcutaneous position for a longer time must be anchored to the skin so that they are not inadvertently pulled out by a draw in the tubes or electric wires connecting the inserted devices to external equipment.
From US 6 056718 is known a medication infusion set having a soft cannula for subcutaneous delivery of medication. The infusion set has a cannula housing carrying the cannula. The housing can be assembled with an insertion hub having an elongated insertion needle extending through the cannula during the insertion of this cannula. When the cannula has been inserted the insertion hub is dismounted from the housing and the needle is withdrawn so that no rigid needle is extending through the skin. Where the cannula is going to be inserted, the skin is covered by a patch which is pierced by the injection needle and the cannula. Thereby the insertion wound is protected against impurities which may cause infection and the environments are protected from unintended exposure to blood due to the insertion. The housing carrying the cannula can on its side facing the skin or the patch be provided with an adhesive by which the housing can be glued to the skin or the patch to form an anchoring of said housing.
According to the invention a mounting platform for trans-dermal medical devices comprising a flexible patch having a first and a second side where the first side carries an adhesive by which the patch is glued to the skin is characterised in that the second side of the patch is provided with a rigid construction defining a piercing zone and carrying needle insertion guides and interfaces for connection of inserted catheters and probes to external equipment.
By utilizing the mounting platform according to the invention it is ensured that trans-dermal devices are inserted within a pre defined area of the skin and that the insertions are made to the optimal depth and under the optimal angles. Inserted probes and catheters leads to inter- faces mounted on the rigid construction to which interfaces connections to external equipment is connected so that mechanical stresses in the external connections are absorbed by the rigid construction and not transmitted to the inserted probes and catheters. Also the external connection may be changed without withdrawal of the already inserted probes and needles. The external connections may be tubing for medicine infusions or electric conduc- tors for transmission of electrical signals from probes.
The insertion zone may be prepared with one or more biochemical active agents like a disinfection agent or an anaesthetic. Due to well defined insertion zone the influence of the anaesthetic and disinfector can be limited to this small zone. Furthermore, the insertion zone may have mechanical and adhesive properties different from the surroundings, thus making insertion of the device easy. As an example, many adhesives show a high degree of tackiness. Thus the adhesive may adhere to the trans-dermal device, causing a non-wanted pollution of the trans-dermal cavity. This can be prevented by using a special adhesive showing a low tackiness close to the insertion point,
In the following, the invention will be described in further details with references to the drawings, wherein
Figure 1 shows an embodiment of a patch with a rigid mounting platform,
Figure 2 shows the mounting platform in figure 1 with a catheter insertion device guided by the platform, and
Figure 3 shows schematically a sectional view of a patch with a rigid platform during the insertion of a needle.
Figure 1 and 2 exemplify how a flexible patch 1 with rigid platform 2 can be utilised. The rigid platform has a guide for an insertion needle 3 by which a biosensor 4 is subcutaneously inserted through the patch 1 by a sensor insertion apparatus comprising the said insertion needle 3, a circular spring element 5 which can be compresses to an oval shape when a
press button 6 is pressed, and an abutment member 7 which abuts an abutment surface on the platform 2.When the spring retains its circular shape, the insertion needle is withdrawn and leaves the inserted catheter 4 in a subcutaneous position. When the catheter insertion apparatus is removed, the outer end of the catheter can be mounted to an interface mounted on the platform.
Figure 3 shows schematically the flexible patch 1 with the rigid platform 2 mounted on it and by which platform a needle 10 carried by a needle insertion device 11 is guided and the platform forms a support for the insertion device. The side of the patch 1 which faces the skin of a patient is provided with a bonding material 8 which glues the patch hermetically to the skin to prevent that any kind of contamination finds its way between the skin and the patch 1. In the area 9 wherein the insertion needle and the catheter, or a possible electrode, pass through the patch into the skin, the adhesive may be prepared to be bio-chemically active, e.g. having disinfecting or anaesthetic properties.