Surgery – Truss – Pad
Patent
1993-10-22
1995-02-07
Rimell, Sam
Surgery
Truss
Pad
128760, A61B 514
Patent
active
053868340
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus for withdrawing arterial blood with a protective tube with mounting member, which includes a conical seat for the receipt of a hollow needle and two capillaries held in the protective tube of which the first is in communication with the hollow needle and the second via a deflecting member, in which the two capillaries are held in a seat, with the first capillary, whereby the ends of the capillaries facing away from the deflecting member are held in the mounting member and the protective tube and the mounting member for the hollow needle are made integrally.
A known apparatus for withdrawing blood of this kind is known from the DE 28 36 780 C2.
At a further known apparatus of this kind available under the trademark "MIKRO-PUNKTIONS-KIT" (Prospect of the company VAL Medical Instruments AG, Schaffhausen, Switzerland) the protective tube and the mounting member are made separately from each other, whereby the mounting member can be plugged onto the protective tube in a cap-like fashion. Apparatuses of this kind operate without the aid of the aspiration piston, whereby the blood flows into the hollow needle and from there into the capillaries due to the pressure of the blood. In order to transfer the withdrawn blood into a blood analysis apparatus the mounting member designed as cap is pulled off the protective tube, whereafter the capillaries can be pulled out of their seat in the deflecting member.
Due to a simple and safe mounting and also dismounting of the mounting member it has been produced at the known apparatus from a soft plastic material, preferably polyethylene. This material is, however, only translucent, therefore not clearly transparent. Accordingly, no safe checking of the last filling area of the second capillary is possible at this known apparatus. Also, due to the softness of the material no rigid connection between the hollow needle and the conical seat of the mounting member is possible. Therefore, there is the danger of an unintended detaching of the hollow needle from the mounting member, wherewith the operator may come into contact with the blood of the patient. The position-wise correct assembling in relation to the two capillaries of different length and also the demand of an easy to handle, small structural size led to the oval cross section of the known apparatus. This cross section is however quite difficult to control regarding leakage during the assembling of the deflection member onto the protective tube.
At the above mentioned known apparatus according to the DE 28 36 780 C2 the drawback of the loose mounting member which is designed as cap is overcome indeed because the mounting member and the protective tube are designed integrally, however, there still remains the drawback of the oval cross section of the protective tube because the two capillaries are still located adjacent each other.
Newer blood analysis apparatuses need due to a larger range of analyses a larger volume of blood. This is, however, without a decisive changing of the known apparatus attainable only via an enlarging of the inner diameter of the capillaries. This enlarging is, however, subject to limits. On the one hand the assembling and later removal of the capillaries out of the apparatus necessitate a certain stability, i.e. safety against breakage, and accordingly, a certain minimal wall thickness of the capillaries consisting of glass. On the other hand the diameter cannot be enlarged arbitrarily, because in order to obtain an impeccable blood analysis the blood must be prevented from a premature coagulation. For this reason the capillaries were heparinized at the surface of the inner side, i.e. provided with a chemical preventing a coagulation. The wettability, i.e. the action of the heparin onto the bloodstream in the capillaries decreases, however with a decreasing distance from the walls acted upon. Conclusively, it is possible that partial coagulations arise at the inside of the bloodstream which influence negatively the analysis.
The object of the invention is
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AVL Medical Instruments AG
Rimell Sam
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