DE19624215C1 - Implantable infusion pump with coil and capacitor in resonant circuit - Google Patents

Abstract

The pump has a housing (10) divided into a medicament chamber (12) and a propellant chamber (14) by a partition (16). The medicament is expelled, under the pressure of spiral springs (22) under the partition, from a bag (24) through a constriction (20) leading to a catheter (18). A compression spring (30) fixed to the partition on its propellant side acts on a variable capacitor (28) serving as a pressure gauge in conjunction with a coil (26) lying outside the bag in the medicament chamber. The frequency of resonance varies with the position of the partition between the chambers.

Description

The invention relates to an implantable infusion pump with the Merk paint the preamble of claim 1.

Such infusion pumps, such as those from the DE 26 04 113 C2 are known, patients in planted that continuously over a long period of time are to be supplied with a medication, for example Pain patients or spastic patients.

It is desirable for the amount of implanted in the Infusion pump still existing medication with a to be able to record high accuracy. On the one hand, this is important for determining whether an exchange  or refilling the pump is necessary, secondly but a regular measurement of the level can also give a statement about the function of the pump.

From DE 39 23 079 A1 it is known the fill level an infusion syringe by detecting one at the Ent empty capacity change.

The invention has for its object an implan to create a viable infusion pump in which the respective current level can be determined from the outside.

According to the invention, this object is achieved by the features of claim 1 solved. The subclaims given above partial embodiments of the invention.

The invention is described below with reference to a drawing explained. The only figure shows an invented one Infusion pump designed according to the invention in a schematic table sectional view using the example of a spring pump. It it should be noted, however, that the inventive provision a resonant circuit that can be queried from the outside, whose resonance frequency a function of the respective level the infusion pump is also realized with a pump light in which the medication room or the Propellant chamber is designed as a bellows.

The infusion pump consists of a housing 10 which forms a medicament chamber 12 and a propellant chamber 14 , the two rooms being separated from one another by a wall 16 . In the area of the center of the propellant space, a throttle path 20 is arranged on the housing 10 .

The medicament chamber 12 accommodates a bag 24 made of a high-pressure-resistant material, into which the medicament to be dispensed via the throttle section is filled. The bag 24 is guided to the throttle section 20 via a hose which is resistant to high pressure.

The outlet of the throttle section 20 leads to a catheter 18 which is laid in the body of the patient to be cared for.

A spiral spring 22 closed to a ring, the plane of which is parallel to the plane of the wall and the turns of which are oblique to the direction of the load, acts between the underside of the housing 10 and the wall 16 and thus acts on the bag 24 with high pressure.

The propellant chamber 14 is further filled with a propellant used to balance the volume.

In the propellant chamber 14 , a compression spring 30 is provided in the center, which is fixed to the wall 16 . The compression spring 30 acts on a capacitive Manome ter, that is, a capacitor 28 , the capacity of which changes depending on the pressure exerted on it.

On the upward-facing (that is, after implantation facing outward) side of the housing 10 , a coil 26 is arranged, which is connected via electrical lines 32 to the pressure gauge capacitor 28 to form a resonant circuit.

The resonant frequency of through the coil 26 and the capacitor 28 formed Kon resonant circuit is determined by the eg large capacitance of the capacitor 28, which is dependent as derum by the pressure exerted by the compression spring 30 thereon. Since the pressure spring is fastened to the wall of 16 30, the pressure on the condenser pressure gauge 28 is due to the Hooke's Geset zes the spacing of the wall 16 depending from the capacitor manometer 28th Since the wall 16 increases with increasing delivery of the medication from the bag 12 through the throttle section 20 and the catheter 18 into the patient's body, the pressure exerted by the compression spring 30 on the condenser pressure gauge 28 is a measure of the level.

The pressure that the spring 30 exerts on the condenser manometer 28 can be determined from the outside by querying the resonance frequency of the resonant circuit formed by the components 26 , 28 . This it follows that a variable AC voltage is given up from the outside and the current required to maintain the vibration is measured. Upon reaching the resonant frequency of the reactance increases the oscillating circuit significantly (EI ner parallel connection of the components 26, 28 and fixed Lich (by a series connection of the components 26, 28). This resonant frequency is determined and the filling level, the respective resonance frequency corresponds to the resonant circuit.

It goes without saying that an inductive manometer 26 could also be used instead of the capacitive manometer 28 . Furthermore, a tension spring can also be used instead of a compression spring 30 .

The invention can also use touch continuously working inductive or capacitive displacement measurement systems can be realized.

The invention is further not limited to the use of a coil spring 22 as the pressure on the wall 16 generating element, it can also - as usual - a bellows that receives a propellant, who used the.

Claims (3)

1. Implantable infusion pump with a housing ( 10 ), a medication chamber ( 12 ), a propellant chamber ( 14 ), a medicament chamber ( 12 ) from the propellant chamber ( 14 ) separating wall ( 16 ) and one communicating with the medicament chamber ( 12 ) and to a throttle section ( 20 ) leading to the catheter ( 18 ) to be laid in the patient's body,
characterized by a by a coil (26) and a capacitor circuit (28) electric oscillating formed, wherein either the coil (26) or the condensate sator (28) at its one side to the housing (10) immovably fixed and at its other Is coupled to the wall ( 16 ) and is designed as a function of the location of the wall ( 16 ) relative to the housing ( 10 ) to determine the resonance frequency of the resonant circuit of the element. 2. Infusion pump according to claim 1, characterized in that the element is a condenser pressure gauge ( 28 ), the other side of which is attached to the wall ( 16 ) via a spring ( 30 ). 3. Infusion pump according to claim 1 or 2, characterized in that the coil ( 26 ) is ausgebil det as an antenna which receives an external voltage applied to query the resonance frequency of the resonant circuit.