Device for the dosed delivery of a fluid

An apparatus is proposed for the dosed dispensing of a fluid, especially an infusion fluid, comprising a housing (1) with a fluid chamber and a pressure medium chamber (3) by which a flexible wall (4) of the fluid chamber can be pressurized from the outside with a pressure medium. In order to provide a re-useable infusion pump with especially simple means it is proposed that the housing (1) consists of two mutually detachably joined housing parts (6, 7), of which the one comprises the pressure medium chamber (3) and the other receives in an exchangeable manner the fluid chamber configured as a leak-proof infusion bag (2), and that the housing part (6) with the pressure medium chamber (3) is sealed by a membrane (5) against the housing part (7) receiving the infusion bag (2) and is connected to a gas pressure source (11).

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of Austrian Application No. A 1224/2003 filed Aug. 4, 2003. Applicant also claims priority under 35 U.S.C. §365 of PCT/AT2004/000274 filed Aug. 3, 2004. The international application under PCT article 21(2) was not published in English.

FIELD OF THE INVENTION

The invention relates to an apparatus for the dosed dispensing of a fluid, especially an infusion fluid, comprising a housing with a fluid chamber and a pressure medium chamber by which a flexible wall of the fluid chamber can be pressurized from the outside with a pressure medium.

DESCRIPTION OF THE PRIOR ART

In such a known apparatus (WO 95/23 641 A1), the fluid chamber, the pressure medium chamber and a gas pressure generator are housed in a common housing. The gas pressure generator consists of a reaction chamber which contains an organic acid, mostly citric acid in the required concentration, and a carbonate preparation, mostly sodium carbonate with binding agents, which is separated from the container by a membrane and is pressed into a tablet. For the purpose of activating the gas pressure generator, the membrane is separated between the acid and the carbonate, whereupon the carbonate reacts with the acid and subsequently releases a reaction gas, mostly carbon dioxide, which is guided via a hydrophobic gas-permeable membrane and a cannula to a pressure medium chamber from where the infusion fluid is pressurized via the flexible wall of the fluid chamber. The infusion speed can be regulated via the gas pressure and/or a control valve in the infusion cannula leading from the apparatus to the patient. Such apparatuses for the dosed dispensing of an infusion fluid come with the advantage that a patient can be supplied with an infusion fluid over a prolonged period at virtually constant pressure, with the patient remaining mobile during the dispensing of the fluid because her or she is able to carry the apparatus on the body. It has proven to be a disadvantage in connection with this known apparatus that it is merely a disposable product which is relatively expensive to produce and needs to be disposed of at increased expense after use.

SUMMARY OF THE INVENTION

The invention is therefore based on the object of providing an apparatus for the dosed dispensing of a fluid, especially an infusion fluid, which can be produced in a cost-effective way, is mostly re-useable and causes only very low operating costs.

This object is achieved by the invention in such a way that the housing consists of two mutually detachably joined parts, of which the one forms the pressure medium chamber and the other receives the fluid chamber configured as a leak-proof infusion bag in an exchangeable manner, and that the housing part with the pressure medium chamber is sealed by a membrane against the housing part receiving the infusion bag and is connected to a gas pressure source.

The invention provides a re-useable apparatus for the dosed dispensing of a fluid in a simple way, such that drugs filled or diluted in infusion bags, or pesticides or fertilizers for plants, can be used in a simple way in the apparatus. Infusion bags of different dimensions and filling quantities can be used in an apparatus in accordance with the invention. Prior to the dosed dispensing of the fluid it is merely necessary to insert the infusion bag into the respective housing part and the two housing parts only need to be joined with each other in a rigid fashion, whereupon the pressure medium chamber can be filled with a pressure medium in such a way that it acts via the membrane directly upon the jacket of the infusion bag and thus ensures the expulsion of the fluid or the infusion fluid from the fluid chamber with the desired pressure. Because the housing part with the pressure medium chamber is sealed by a membrane against the housing part receiving the infusion bag and is connected to a gas pressure source, an especially simple, reliable and re-useable construction of an apparatus in accordance with the invention is obtained, which in addition causes only very low operating costs. The gas pressure source is connected for example to the housing part forming the pressure medium chamber or is inserted into a respective recess formed by the pressure medium chamber, thus leading to especially compact conditions.

One of the two mutually detachably joined housing parts thus receives the pressure medium chamber sealed by a membrane and the other housing part receives the infusion bag, which allows performing a change of the infusion bags in an especially rapid and simple manner. Moreover, it is recommended in accordance with an advantageous embodiment of the invention that the two housing parts are joined in an articulated manner on one side and comprise a latching device on the opposite side, as a result of which the two housing parts can be opened relative to each other, but still remain mutually joined in a non-losing way and can be mutually latched.

Gas pressure generators especially known from WO 95/23641 A1 are especially recommended as gas pressure sources, which are preferably connected via a control and/or pressure reducing valve to the pressure medium chamber in order to ensure the most constant adjustable pressure over the entire dispensing period of the infusion fluid and to enable an interruption of the gas supply to the pressure medium chamber at any time. A conventional pressure relief valve can be provided in the simplest of cases as a pressure reducing valve. For regulating the venting and for resetting the membrane or for diverting the gas when changing the infusion bag or the gas generator, it is advantageous when the gas pressure source remains joined in an exchangeable manner to the control or pressure reducing valve associated with the housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An apparatus in accordance with the invention for the dosed dispensing of an infusion fluid comprises a housing1which receives a flexible fluid chamber in the form of an infusion bag2and a pressure medium chamber3, through which a flexible wall4of the infusion bag2can be pressurized with a pressure medium from the outside via a membrane5. The housing1consists of two housing parts6,7which are joined in an articulated manner with each other on one side by means of two hinge joints8and comprises on the opposite side a latching device9with which the two housing parts6,7can be fixed in their position in a mutually closed position with respect to each other.

In connection with the two detachably connected housing parts6,7, the one housing part6receives in an exchangeable manner the pressure medium chamber3and the other housing part7the leak-proof infusion bag2. The housing part6with the pressure medium chamber3is sealed by membrane5relative to the housing part7receiving the infusion bag2and is connected via a duct10to an exchangeable gas pressure source11. The membrane is glued or welded together with the associated housing part6in the region of the separating plane of the two housing parts6,7. A control valve12and pressure reducing valve13are arranged between the gas pressure source11and the pressure medium chamber3with which the gas supply from the gas pressure source11to the pressure medium chamber3can be controlled or regulated and the gas pressure can be limited to a pre-adjustable maximum value. Since after the use of the apparatus in accordance with the invention it is merely necessary to exchange the gas pressure source11and the infusion bag2and the remaining apparatus can be re-used, the gas pressure source11is connected in an exchangeable manner via a plug-in coupling14with the control valve12which is associated with housing1.

The gas pressure source11consists of a container15with a hydrophobic gas-permeable membrane16which receives an organic acid17, especially citric acid, in the required concentration and of a carbonate preparation, especially sodium carbonate with binding agents, which is separated from the acid17by way of a film18or the like and is pressed into a tablet19.

For the purpose of using the apparatus in accordance with the invention, an infusion bag2is placed in the opened housing1(seeFIG. 3), with the infusion cannula20being closed by means of a clip (not shown) and thereafter the housing part6receiving the pressure medium chamber3is locked with the housing part7receiving the infusion bag2. Thereafter the gas pressure source11is activated in such a way that the tablet19is brought into contact with the acid17by destroying the film18, whereupon the pressure medium, especially carbon dioxide, is produced as a result of the subsequently occurring chemical reaction. The gas-permeable membrane16ensures that merely gases reach the pressure medium chamber3and the fluids are held back in the container15. The gas pressure source11is principally determined for single use. Under certain circumstances it is possible to infuse several infusion bags in direct succession with the same gas pressure source11. This depends on the bag volume and infusion speed. After the start of the reaction in the gas pressure source11, the gas is introduced from the container15via the control valve12into the pressure medium chamber3where the membrane5sits close against the flexible wall4of the infusion bag2and pressurizes the infusion fluid contained in the infusion bag2with the desired pressure for expelling the infusion liquid from the infusion bag2through the infusion cannula20. After the completion of the infusion process, the infusion bag2can be removed from the opened housing1and be disposed of. The gas pressure source11can be removed from the housing1, whereupon the membrane5is reverted back to its starting position when the control valve12is opened. The apparatus in accordance with the invention is ready for renewed operation after the insertion of a new infusion bag2into the housing1and the attachment of a new gas pressure source.