Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1996-02-21
1998-09-22
Derakshani, Phillipe
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604246, A61M 3700
Patent
active
058107789
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention refers to an apparatus for a controlled delivery of liquids. More specifically, the invention refers to an apparatus for such a delivery which may be varied during the time of delivery. Still more specifically, the invention refers to an apparatus for such a delivery of a pharmaceutical preparation by parenteral injection or infusion. Especially, the invention refers to such an apparatus which is independent of any external power source for its function.
BACKGROUND OF THE INVENTION
Devices for a controlled delivery of liquids, especially by parenteral injection or infusion, are previously known. Such devices are used when it is desired to administer a liquid preparation to a patient for an extended period of time. The preparation is expelled from a suitable container by some suitable driving force, and the delivery is controlled by arranging a suitable constriction in the conduit or line from the container to the patient receiving the administered liquid.
There are no problems in arranging this controlled delivery in a hospital where the driving force may simply be the hydrostatic head achieved by hanging up the container in an infusion stand of a well-known type. Furthermore, a number of infusion pumps are known, which are dependent on an external power source, such as electricity or compressed air. These pumps may also be programmed to give a delivery which can be varied with the time.
However, difficulties arise when a controlled infusion or injection is to be administered for an extended time where hospital facilities are not available, such as in the ambulatory treatment of accidents or sudden illnesses, such as heart attacks. For instance, in the treatment of a heart infarct, an administration of an antithrombotic agent, such as streptokinase, will often have to be given for an extended time of about an hour or more, where no programmed infusion pumps depending on an external power source are available.
There have been developed devices for administering parenteral injections or infusions for an extended period of time, which are not dependent on any external power source for driving an infusion pump. In one suitable embodiment of such devices, a vacuum is established in a chamber which is provided with a movable piston. The atmospheric pressure on the opposite side of the piston strives to move the piston into the vauum chamber, and through a suitable mechanical connection, such as a piston rod, this movement actuates a piston in an infusion pump or syringe to expel a preparation from said pump or syringe to administer it to a patient. The time for the administration is controlled by a suitable constriction in the flow path of the administered preparation.
Such devices have a number of important advantages. As the driving force is achieved by the atmospheric pressure acting against a vacuum, and not by any kind of gas-generating material, as is also previously known the force is constant over the time for administration. This means that a constant amount of the preparation is administered per unit of time. Furthermore, no gas-generating and potentially hazardous materials have to be handled. Also, in a specially preferred embodiment, the vacuum is established immediately before an infusion is administered. This eliminates the risk that the device becomes inoperative because of leaks having destroyed the pre-established vacuum.
Devices of the type mentioned above have been described in the international patent application No. PCT/SE91/00506, and have given good service. However, there is still room for improvement of these devices. As stated above, the amount of preparation administered per unit of time is essentially constant, because of the constant pressure acting on the piston against the vacuum. In certain applications, however, it is desired to administer a greater amount of preparation during an initial stage of the infusion, and a smaller, constant amount per unit of time during a later stage. One example of such an application is when agents are admi
REFERENCES:
patent: 4744786 (1988-05-01), Hooven
Derakshani Phillipe
Pharmacia & Upjohn Aktiebolag
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