DE29512576U1 - Filling septum - Google Patents

Description

The invention relates to a filling septum for an infusion pump with a valve on a spring-loaded needle stop below a filling plug.

In practice, every infusion pump has a medication reservoir that can be refilled. This refilling takes place through a refill septum.

According to the known state of the art, the filling septum can be secured by a rigid needle stop (US-PS 5,049,141) or by a movable needle stop (US-PS 4,557,722). In the second case, the needle stop is pressed downwards with the needle during the injection, whereby an opening opens from the septum to the medication chamber, through which the medication stream can flow into the medication reservoir. If the injection needle is removed again, a spring pushes the needle stop upwards and the medication chamber or medication reservoir is closed again.

The disadvantage of the known needle stops is that the needle tip must first penetrate a silicone plug in front of the needle stop and then presses on the needle stop. The injection needle is pointed at the front. This can lead to the injection needle below the silicone filling plug being damaged when it hits the hard needle stop body. When the needle is pulled out, the silicone filling plug can be damaged or the human tissue above the filling septum can be damaged.

It is the object of the invention to create a filling septum which, on the one hand, ensures safe filling of the medication reservoir of an infusion pump and, on the other hand, avoids damage to the injection needle as far as possible.

This object is achieved according to the invention by the characterizing part of the first patent claim.

By placing a soft body on the needle stop, you ensure that the injection needle is slowed down when it hits the needle stop and cannot break off so easily.

Of course, the injection needle partially penetrates the soft body, which is why the outflow hole in the injection needle must still be above the soft body when the injection needle has penetrated the soft body and when the needle stop is pressed down.

A lateral guide for the needle stop prevents it from jamming.

Designing the spring as a leaf spring makes it easier to manufacture and ensures greater operational reliability.

Arranging the leaf spring under the needle stop ensures a very compact design of the needle stop, as in the extreme case it only forms a flat body.

The soft body is advantageously made of a material that does not absorb liquids, so that when changing the medication to be filled into the medication reservoir, there is no contamination from the medication previously used. This also makes it easier to clean the infusion pump when it is implanted.

It is therefore advantageous if the soft body is made of silicone.

It is advantageous if the filling septum is attached to or in the infusion pump in an exchangeable manner, so that after replacing the infusion pump and replacing the filling septum

can be reused (e.g. by reimplantation into the patient’s body).

The needle stop body should preferably be made of plastic, as plastics have a certain flexibility when subjected to pressure, making it less likely that the needle will break or the needle tip will bend. The plastic material must be resistant to the medication to be used, so that no material can escape from the plastic.

Advantageously, the soft body on the needle stop seals the medication reservoir, as the elasticity of the soft body allows for a very secure seal.

A spacer ring should be placed between the filling plug and the soft body to ensure the clearance between the upper soft body (e.g. made of silicone) and the soft body (e.g. made of silicone) on the needle stop for filling.

The invention is explained in more detail below by way of example with reference to five drawings, in which further essential features as well as explanations and possible embodiments of the inventive concept are described for a better understanding.

Showing:

Figure 1 shows a section through the filling septum according to the invention;

Figure 2a is a plan view of the filling needle stop body;

Figure 2b is a side view of the body of Figure 2a;

Figure 3a is a plan view of the spring below the filling needle stop body; and

Figure 3b is a side view of the spring from Figure 3a. - -

The filling septum of an infusion pump shown in Figure 1 consists essentially of a base plate (1) onto which a filling cap (9) is screwed. This filling cap (9) is designed as a screw ring. It is hollow inside and has a continuous central opening. A sealing ring between the filling cap (9) and base plate (1) seals this arrangement by being deformed when screwed together. A silicone filling plug (3) is located in the screw ring (9).

This silicone filling plug (3) is secured from below by a filling ring (6) made of a material that does not react with body fluids (e.g. titanium), so that the silicone filling plug (3) cannot move in its fixed position. For this purpose, the filling ring (6) has an upper support surface for the silicone filling plug {3) and the filling cap (9) has a lower support surface for the silicone filling plug {3). The filling ring {6) rests with its lower surface partly on the base plate (1) or a flange (7).

A soft body {4) (lower silicone filling plug) fastened in the needle stop body (5) made of PE plastic (see in particular Figures 2a and 2b) presses against the filling ring (6) from below, whereby the pressure on the needle stop body (5) is exerted upwards by a spring (8) mounted underneath it. However, the pressure generated by the liquid on the underside of the needle stop body (5) is many times greater than the pressure exerted by the spring (8). Consequently, the spring (8) only has a supporting effect when the valve is open (pressure equalization between the medication chamber (2) and the gap (10)) in order to initiate a closing process of the valve.

This spring (8) (see especially Figures 3a and 3b) is designed as a leaf spring. In this position, the filling ring (6) together with the soft body (3) in the needle stop body (5) seals the medication reservoir located below the needle stop

(2) in a diaphragm bellows. The spring (8) has a lower support surface on the flange (7).

The filling ring (6) has an upper and a lower flat surface. Its outer circumference is circular. Its inner circumference is essentially trapezoidal, with the opening in the inside of the filling ring (6) widening towards the silicone filling plug (3). At the lower end of the inner circumference, the filling ring (6) has a rounded nose so that the soft body (4) in this area is not damaged during the closing movement of the needle stop (5) and closes sufficiently.

The soft body (4) is clamped into the needle stop body (5). The needle stop body (5) is designed so that it has a smooth contact surface for the underside of the soft body {4}. The needle stop body {5) is shaped like a cylinder disk and has a smooth, flat underside. Its outer circumference is essentially circular. Its inner circumference is circular and serves as a smooth contact surface for the circular outer circumference of the soft body (4). In the upper part of the soft body (4), it has a spherical, smooth outer ring on the top. This serves as the lower contact surface of a circular tapering of the needle stop body (5). Between this circular tapering of the needle stop body (5), the soft body (4) protrudes beyond the needle stop body (5) and hits the rounded nose in the inner circumference of the filling ring (6) from below.

There are several incisions in the outer circumference of the needle stop body (5) (three are shown in the figure), which allow the injected medication to flow into the medication reservoir (2) when the needle stop body (5) is pressed down.

The spring (8) {see especially Figures 3a and 3b) is designed as a round leaf spring and is divided into several circular ring segments (there are three in the figure), with each circular ring segment

has an inward-projecting extension arm. All extension arms meet at the center of the round leaf spring. There is an air gap between the individual circular ring segments. At the ends of the circular ring segments at the air gaps, these have a small extension towards the center of the circle of the spring (8). In order for the leaf spring to have its springy effect, the circular ring segments are slightly twisted against each other (see Figure 3b). In Figure 3b, the spring (8) is shown in the relaxed state. By applying pressure to the upper and lower surfaces of the spring, it is compressed until it is only a flat disk in the maximum deformation position. If the pressure is released again, the spring relaxes and returns to its original position, whereby a distance forms between its upper and lower surfaces, which serves to close the medication reservoir (2) when the spring (8) is installed. When installed, the upper area of the spring (8) rests on the underside of the needle stop (5). On the flange (7) that is firmly connected (screwed) to the base plate (1), in the area of the spring (8) there is a hole in which a support ring is formed. The spring (8) rests with its underside on the top of this support ring and is thus fixed in the position of use.

The thread for screwing the filling cap (9) is also used for screwing the flange (7). The flange (7) has a circular ring-shaped elevation on the top of which the filling ring (6) rests.

If the medication reservoir (2) is to be filled, an injection needle (not shown in Figure 1) must penetrate through the upper silicone filling plug (3). The design of the filling ring (6) ensures that the injection needle will definitely hit the lower silicone filling plug (4). The injection needle penetrates the lower silicone filling plug (4) and hits the plastic filling needle plug (5) and pushes it down.

The injection needle must have an opening for the exit of the medication to be filled, which, when it hits the filling needle stop (5), is located in the cavity (10) between the upper silicone filling plug (3) and the lower silicone filling plug (4).

By pressing the infusion needle down against the force of the spring (8) and the pressure on the filling needle stop (5), the filling needle stop (5) is pressed downwards, allowing the medication to flow past it at the side (with a pressure greater than that present in the medication reservoir (2)) and thus reach the medication reservoir (2).

When filled, the medication reservoir (2) is under an overpressure of normally around 2.5 bar. The pressure is created from the outside by an inert two-phase mixture, which is partly liquid and partly gaseous and always ensures the same pressure regardless of the filling level of the medication reservoir (2). The spring force acting on the filling needle stop is normally 1/10 of this pressure.

The advantage of the new filling septum is double security against medication leakage and simplified filling. No separate shut-off valves or clamps are necessary and the entire filling septum can be dismantled. Ultimately, the medication in the medication reservoir (2) is separated by two silicone membranes. This creates permanent security against leakage. '

In the event of a leak in the upper silicone membrane in the filling septum, the medication reservoir (2) is sealed by the lower silicone filling plug (4) and it is ensured that no medication can escape uncontrollably from the infusion pump. The upper filling plug can be removed so that it can be easily replaced if necessary.

Claims (10)

Expectations: 1. Filling septum for an infusion pump with a valve on a needle stop (5) spring-loaded by a spring (8) below a filling plug (3), characterized in that a soft body (4) is arranged in the needle stop (5). 2. Filling septum according to claim 1, characterized in that the needle stop (5) is designed such that it has a lateral guide for its vertical movement. 3. Filling septum according to one of claims 1 or 2, characterized in that the spring (8) is a leaf spring. 4. Filling septum according to one of claims 1-3, characterized in that the leaf spring (8) is arranged under the needle stop (5). 5. Filling septum according to one of claims 1-4, characterized in that the soft body (4) is made of a material that does not absorb liquids. 6. Filling septum according to one of claims 1-5, characterized in that the soft body (4) is made of silicone. 7. Filling septum according to one of claims 1-6, characterized in that the filling cap (9) of the filling septum is attached to the infusion pump (1) in an exchangeable manner. 8. Filling septum according to one of claims 1-7, characterized in that the needle stop body (5) is made of a plastic. 9. Filling septum according to one of claims 1-8, characterized in that the soft body (4) in the needle stop -(5-).. seals the medication reservoir (2). 10. Filling septum according to one of claims 1-9, characterized in that a spacer ring (6) is arranged between the filling plug (3) and the soft body (4).