Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1988-05-23
1990-10-30
Pellegrino, Stephen C.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604167, 604283, A61M 500
Patent
active
049665880
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a device suitable for the administration of a therapeutic substance, for example insulin, especially but not necessarily on an intermittent basis.
Insulin-dependent diabetics rely upon subcutaneous doses of insulin administered, and usually self-administered, by means of a syringe and a hypodermic needle. This involves the psychological trauma of self-injection, as well as the inconvenience of the overall procedure. Insulin may also be delivered by electrical, mechanical or hand-operated pumps.
Alternatively, it is also possible to use an indwelling needle through which insulin may be administered. The facility to give injections via indwelling needles is not new (see, for example U.S. Pat. No. 4,568,335), but there are two problems with such indwelling needles as currently available. First, the needles are sharp and made of rigid steel, which can be painful in situ; and secondly, in the injection port attached to the needle there is a large "dead-space", that is the space in the device within which insulin will be withheld instead of being expressed to the patient, which gives rise to problems not merely the problems involved in taking account of the dead-space when calculating doses of insulin, but also the further problems which arise when injecting more than one species of insulin. Furthermore, the kind of needles employed for this purpose and their associated apparatus are often designed for giving large volumes of solution, or for sampling blood. Still further, as shown for example in the above-mentioned United States Patent Specification the connection between the feed syringe or the like and the needle cannot be broken, since there is no seal in or associated with the needle itself.
In an effort to eliminate dead-space problems, there has been marketed in the U.K. a so-called "button" infuser, which is said to have a nominal "dead-space" volume of less than 0.33 units of U-100 insulin. However, that "button" infuser again has a steel needle, leading to discomfort; and, while this device is self sealing, it is difficult to ensure that the intermittent injection needle (which has to be inserted into the indwelling needle) is always during its insertion accurately placed, so that first it does not over-penetrate and engage the plastics material in the hub of the indwelling needle, and so that secondly it does not under-penetrate and fail to enter the indwelling needle lumen beyond the self-sealing diaphragm. The cause of this difficulty is that in this known "button" infuser the self-sealing diaphragm takes the form of a relatively thick seal at the mouth of the device; or in other words, the seal is positioned so that it must be pierced before the device can be entered, and this in practice causes entry problems. Thus, for example, where the device is worn say on the patient' s abdomen, the patient must look down and, with a fairly restricted view of the mouth of the device, attempt to penetrate a relatively thick seal, without either under-penetrating or over-penetrating as described above.
We have now found surprisingly that the disadvantages of the known "button" infuser can be avoided, while at the same time still having a dead space of only relatively small volume, by disposing the seal in the body of a cannula hub, the seal being disposed not only adjacent the hub-end connected to the cannula, but also at the distal end of a needle guide passage through the hub, which ensures correct alignment of the injection needle as it passes through the hub and penetrates the seal.
Accordingly, the present invention provides a device suitable for use in the intermittent or even continuous administration of a therapeutic substance (such as insulin), which device comprises a cannula of biocompatible plastics material for indwelling in a patient and defining a through-passage (lumen), together with a hub also defining a through-passage, the respective cannula and hub passages being isolatable from each other by separator means (such as a self-sealing diaphragm) disposed betwee
REFERENCES:
patent: 3097646 (1963-07-01), Scislowicz
patent: 4059105 (1977-11-01), Cutruzzula
patent: 4121585 (1978-10-01), Becker
patent: 4194504 (1980-03-01), Harms
patent: 4559043 (1985-12-01), Whitehouse et al.
Harris Ivan P.
Rayman Gerrard A.
Sugarman Harvey L.
H. G. Wallace Limited
Pellegrino Stephen C.
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