Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1993-06-14
1995-01-17
Hirsch, Paul J.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
6048911, A61M 3100
Patent
active
053822366
DESCRIPTION:
BRIEF SUMMARY
This application is a continuation of parent international application PCT/DE91/00944, filed Nov. 29, 1991 and German P 4038049.1 filed Nov. 29, 1990.
BACKGROUND OF THE INVENTION
The invention relates to an implantable infusion pump with an elastic medicament container, a propellant chamber acting on the latter and having a propellant formed from a chlorofluorohydrocarbon, as well as a restricting capillary tube.
Implantable infusion pumps are used for the long-term administration of medicaments, e.g. morphine in a constant dose over a long period. Compared with conventional injections, they offer the advantage that it is no longer necessary to overdose to such an extent that despite the breaking down of the medicament up to the next adminstration time there is no drop below a certain minimum dose and instead there is a uniform and significantly reduced supply of the medicament.
However, hitherto in the case of infusion pumps of the aforementioned type problems have occurred when the temperature was changed. If the person with such an infusion pump implanted has fever with a body temperature of 42.degree. C., as a result of the additional expansion of the propellant the delivery can be up to 46% more (propellant: trichlorofluoromethane), which is naturally highly undesired.
Similar problems can occur when the atmospheric pressure is changed. Here, e.g. when staying at an altitude of 3000 m, which roughly corresponds to atmospheric pressure and which can occur in an aircraft, there can even be an additional delivery of 55%.
The problem of the invention is therefore to provide an implantable infusion pump, in which such effects play a very minor part and the operational reliability of the pump is improved.
SUMMARY OF THE INVENTION
According to the invention this problem is solved in that the propellant chamber is designed for a filling pressure of more than 2.5 bar above atmospheric pressure and the propellant is 1,2-dichlorotetrafluoroethane (C.sub.2 Cl.sub.2 F.sub.4). For this purpose said propellant has a very suitable vapour pressure curve and is non-toxic, i.e. harmless, if it comes into contact with the body.
It is also proposed that the medicant container is formed from a metal diaphragm corrugated bellows. Once again the latter is preferably made from titanium. This material is light, chemically resistant, sufficiently impervious and mechanically very robust.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a sectional elevational view of the implantable infusion pump of the invention.
DETAILED DESCRIPTION OF THE INVENTION
According to a preferred development an outer container receives the propellant chamber and the medicament container. This outer container is also made from titanium. This offers the same advantages as for the medicament container and additionally also the high biocompatibility of titanium.
The invention is described in greater detail hereinafter relative to the single drawing, which is a sectional view of an implantable infusion pump. The infusion pump comprises an outer container 16 in which is formed a medicament container 10 as a metal diaphragm corrugated bellows, a propellant chamber 12, a capillary tube 14 for restricting the medicament flow and a septum 18, which is used for the supply of the medicament by a doctor with the aid of a syringe and a special needle.
The complete pump shown is implanted in a patient, preferably in the abdominal region. From the infusion pump passes a catheter to the point where medicament administration is to take place, e.g. at the vertebral column.
As a function of the chosen delivery and the pump size, it only has to be filled at long intervals of typically one month. For this purpose use is made of special needles, which can pass in non-cutting manner through the septum 18, which is a type of cork.
Due to the fact that the propellant in under high pressure, temperature changes only have half the effect with the chosen propellant compared with the previous situation and pressure fluctuations can even only represent roughly a quarter of
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Otto Karl-Heinz
Pfister Gerd
Anschutz & Co. GmbH
Hirsch Paul J.
Larson Herbert W.
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