Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1991-03-15
1992-12-08
Rosenbaum, C. Fred
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604198, 604263, 604272, A61M 532
Patent
active
051693917
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a cannula, in particular for puncturing blood vessels, for example for extracorporeal blood therapy, comprising a beveled cannula tip and a cannula holder in which the cannula is mounted, which cannula holder carries on its rear end a flexible tube and is surrounded, at least by sections, by a wing-shaped handle, and comprising further a protector cap covering the cannula tip.
Cannulas of this type are employed, for example, for puncturing body cavities and blood vessels, for example for the purpose of withdrawing blood or for introducing blood or other liquids. It is frequently necessary in such applications that the cannula must dwell in the vessel for an extended period of time, for example for blood dialysis. It must be ensured in these cases that the opening of the cannula cannot be blocked by the wall of the vessel. In order to eliminate this risk, and to provide optimum flow conditions, the cannula is designed in such a way that it can be rotated relative to the handle, which latter may have the shape of a wing and be taped in place on the patient's skin. Given the fact that the flexible tube is normally in contact with the handle, more or less, different torques are typically encountered when rotating the cannula so that exact positioning of the needle is often difficult, and there is always the risk that the blood vessels may be injured.
Now, it is one of the objects of the present invention to improve a cannula of the type described above in such a way that equal conditions are always encountered when turning the cannula so that it is ensured at all times that the opening of the cannula can be turned in the blood vessel safely and without any problems. Further, it is an object of the present invention to give the handle a clearly defined position on the cannula holder. In addition, the invention is to ensure that the handle occupies a desired radial position relative to the cannula holder Finally, the invention is to provide means to enable a used needle to be safely put back into the protector cap.
The invention achieves these objects substantially by the fact that a flexible tube is arranged on the cannula holder at a defined distance from the handle. Preferably, the cannula holder is provided with a shoulder, which may run all around its circumference and with which the flexible tube is pushed into contact. Consequently, the arrangement according to the invention guarantees that the flexible tube is kept clear of the handle so that, consequently, it cannot exercise an uncontrolled influence on the torque when the cannula is turned. As a result of this arrangement, the torques encountered are clearly defined which ensures safe handling of the cannula.
According to one embodiment of the invention, the cannula holder is equipped with a flange which is provided at a certain distance from the rear end of the cannula holder and which is contacted by the flexible tube. If desired, a cylindrical portion of the handle surrounding the cannula holder may also rest against the flange on its opposite side. In addition, there are of course other possibilities of maintaining a spacing between the flexible tube and the handle.
In order to fix the cannula in defined positions, for example in a blood vessel, it is proposed according to an independent aspect of the invention to arrange the handle on the cannula holder in such a way that it can be locked in position. To this end, the cannula holder and/or the handle may be provided with interacting detent projections and detent recesses. The arrangement may be such that the handle rests against a stop projecting from the cannula holder, preferably in the area facing the cannula tip, and that detent pins and/or snap-in recesses extending from the stop, in axial direction of the cannula holder, are provided to interact with detent recesses and/or detent lugs extending from the end portion of the handle which surrounds the cannula holder.
In order to fix the handle in place on the cannula holder, in axial direction, a groove is provi
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patent: 4563177 (1986-01-01), Kamen
patent: 4676783 (1987-06-01), Jagger et al.
patent: 4781692 (1988-11-01), Jagger et al.
patent: 4950242 (1990-08-01), Alvarez
Maglione C.
Rosenbaum C. Fred
Suddeutsche Feinmechanik GmbH
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