Blood withdrawal device

Abstract

The invention relates to a device for accommodating body fluids, comprising a small tube (1) that, at its front end, supports a dome (10) having a pierceable stopper for a guide sleeve (2), which can be pushed onto the dome (10) and which, on the side facing the dome, has a cannula (5) with a valve rubber (3) and, on the side facing away from the dome, has a connecting piece or the front part of a double cannula. The guide sleeve (2) is made of a rigid material and is provided, at its front end located outside of a grip area (8) provided for normal handling, with a flexible section (6). The dome (10) comprises, in a connecting area, a diameter that is greater than the inside diameter of the guide sleeve (2), whereby when the device is assembled for use, the larger dome diameter widens the flexible section (6) that surrounds the connecting area of the dome (10) in a non-positive manner in order to obtain a retention force.

Description

The invention relates to a device for drawing body fluids, having a specimen tube having at a outer end a tip with a pierceable plug for a guide sleeve fittable on the tip and provided on its side turned toward the tip with a needle and with an elastomeric needle-shield tube and on the side turned away from the tip with a connection fitting or the opposite end of a double needle.

Such devices are for example used for drawing blood from a bottle or bag or to take a specimen from a connection vessel of for example urine. In every case there is the problem that the elastomeric needle-shield tube that surrounds the needle and that is collapsed like a bellows when the guide sleeve is fitted to or installed on the tip exerts a substantial sprint return force acting against the forces that retain the guide sleeve on the tip, with the result that the guide sleeve is pushed off the tip. In order to get around this problem, various measures are taken.

In the blood-drawing device described in German 3,049,503, the cap closing the outer end of the specimen tube has a cylindrical axially extending tip. The tip is closed at its outer end by a pierceable plug that is trapped between an inner centrally apertured wall of the tip and an outer-end rim. The tubular guide sleeve, that has on its outer end a holder for a double-ended and pointed needle whose outer end is intended for insertion into a vein while its inner end projects fo far into the guide sleeve that when the guide sleeve is fitted to the specimen tube it pokes through the plug, is axially shiftable and rotatable on the tip. The inner end of the needle projecting from the guide tube is contained in a bag-like tube (elastomeric needle-shield tube) of such length that the inner point of the needle does not initially reach to its closed end.

In order that the guide sleeve stays on the tip in spite of the spring pressure from the elastomeric needle-shield tube the tip is provided with a laterally projecting bump for holding the double-ended needle that fits in an angled slot in the guide sleeve. This holding bump projecting over the slot in the periphery forms a sort of bayonet latch that secures the guide sleeve to the double needle. Such a latch ensures a solid connection of the fitted-together parts of the blood-drawing device, but increase it s production cost. In addition the coupling and decoupling or latching of the guide sleeves requires that the holding bump first be aligned by turning of the specimen tube with the closing screw or plug cap. to align with the slot, which requires some adept manipulation so that the parts can be properly aligned.

German 692 25 609 describes a protective housing for a needle screwed into a needle holder. Here the protective housing is rotatable on the holder to which end the protective housing has a ring forming an inwardly open groove in which a ridge on a tip of the holder fits.

It is an object of the invention to provide a device of the above-described type with a simple and reliable connection for the two interfitting parts that can be produced at low cost, is easy to use, and provides a solid enough retention to resist the spring force (return force) of the needle-shield tube tending to open it.

This object is achieved by the characterizing clause of claim 1.

The diameter relationships of regions of the tip and guide sleeve with one of them oversized to produce the interfit of the resilient part of the guide sleeve and the tip to produce the desired holding force are created by increasing the size of the tip in the seat region, for example by a ridge, cylinder, ribs, taper, segments, or the like. The system of this invention achieves several advantages. As a result of the limited length of the resilient part relative to the overall length of the guide sleeve, there is sufficient gripping force in the defined regions of the end portions for the necessary hold, while a relatively long portion of the guide sleeve remains as usual rigid and not resilient, so that during installation on and removal from the specimen tube one can use a grip region having nothing to do with the gripping action. The spreading effected by the short enlarged diameter of the tip is effective solely in a short region offset from the grip surface. This spreading of the guide sleeves makes it possible to precisely establish and set the amount of hold so that the grip is sufficient to overcome the pushing force of the compressed elastomeric needle shield, thereby preventing the guide sleeve from being pushed off the tip. In spite of the relatively small diameters of the mating parts (guide sleeve and tip) sufficient holding force is obtained so that the parts can be more easily and simply pushed together and pulled apart than a standard tapered luer connection. Complex manipulation is not needed since the parts do not need a precise alignment.

In order to set the resilience of the guide sleeve in the region offset from the rigid grip region, the inner end of the sleeve can be of the same thickness as the rest of the sleeve but be formed with longitudinal slits having a length equal to the length of the resilient region. The slit or slits allow the otherwise rigid material to flex sufficiently for easy use and to still provide the necessary holding force (solid hold) against the spring force of the needle-shield tube.

Alternatively instead of slits the resilient region can be made less thick or of such a material that it produces the desired holding force. When the tip is formed with an annular ridge or a tapered region of a diameter exceeding the inner diameter of the guide sleeve it is possible to injection mold the tip or a cap forming the tip without having to use a mold with movable parts. Even with for example uniformly angularly spaced bumps around the tip or even one such bump the guide-sleeve portion will hold well enough when installed that the guide sleeve is solidly connected with the tip and thus provides the exact prestress or holding force needed.

Further embodiments and particular features of the invention are seen in the claims and the following description of embodiments of a blood-drawing device according to the invention as shown in the drawing. Therein:

FIG. 1 is an exploded view of a specimen tube with a guide sleeve;

FIG. 2 is an overall view of the guide tube fitted over the tip of the specimen tube of FIG. 1;

FIG. 3 is an exploded view of another embodiment of the specimen tube and guide sleeve;

FIG. 4 is an overall view of the guide tube fitted over the tip of the specimen tube of FIG. 3;

FIG. 5 is a section taken along line V-V of FIG. 3;

FIG. 6 is an exploded view of yet another specimen tube and guide sleeve;

FIG. 7 is an overall view of the guide tube fitted over the tip of the specimen tube of FIG. 6; and

FIG. 8 is a section taken along line VIII-VIII of FIG. 6.

A blood-drawing device according to FIGS. 1 and 2 comprises a specimen tube 1 with a tip 10 and guide sleeve 2 provided in all embodiments for example with a luer fitting and holding a needle 5 having a point 4 and surrounded by an elastomeric shield tube 3. In other embodiments of the guide sleeve, its side turned away from the tip has a connector or the outer part of a double needle. The side of the guide sleeve 2 turned toward the specimen tube 1 is provided with a resilient part 6 formed in FIGS. 1 and 2 as a sleeve 7 of lesser wall thickness than the rest of the guide sleeve 2. Above this part 6 the guide sleeve 2 is formed of relatively stiff plastic with uniform thickness and a thus offers a grip surface 8 that is particularly convenient for installing and removing it from the specimen tube.

The specimen tube 1 is closed at its upper end by a cap 9. It has the tip 10 that starting about halfway along its length has a large-diameter frustoconical region 11 that is slightly bigger than an inside diameter of the guide sleeve. When the blood-drawing device is used the guide sleeve is fitted to the tip 10 of the specimen tube 1 as shown in FIG. 2. When the guide sleeve 2 is fitted to the tip 10, the needle 5 pierces with its tip 4 through an unillustrated plug fitted in the cap 9 until the tip is exposed inside the specimen tube; the also pierced elastomeric needle-shield tube 3 is crushed like a bellows as shown in FIG. 2. The fit between the part 6 and the region 11 of the sleeve 2 on the tip 10 is enough to resist the spring return force of the needle-shield tube 3, since the oversize tip 10 is surrounded tightly by the coupling region with the necessary force.

The embodiments of the blood-drawing device according to FIGS. 3 to 5 or 6 to 8 only differ from FIGS. 1 and 2 by the construction of the resilient part of the guide sleeve or of the tip of the cap of the specimen tube so that similar parts have the same reference numerals; what is common to all embodiments is that the oversize tip spreads the elastic portion of the guide sleeve so that the guide sleeve is solidly connected with the tip.

In the blood-drawing device according to FIGS. 3 to 5 the elasticity of the part 6 near the grip region 8 is provided here by four longitudinal slits 12 (see FIG. 5) in the same region that define or delimit deflectable fingers 14. The tip 10 here has a raised portion constituted as a diameter-increasing ring or ridge 13 that spreads the section 6 or the fingers 14 defined by the slits 12 when the guide sleeve 2 is fitted to the tip 10 (see FIG. 4) so that the guide sleeve 2 is solidly secured to the specimen tube 1 with a force that is greater than the oppositely effective return force of the elastomeric needle-shield tube 3.

The variant on the blood-drawing device according to FIGS. 6 to 8 also has a guide sleeve 2 with longitudinal slits 12 and fingers 14 defined thereby in the part 6 as described above with reference to FIGS. 3 to 5. To spread the part 6 when fitting the guide sleeve 2 to the tip 10 of the cap 9 of the specimen tube 1, the tip is provided with a frustoconical region 11 at the base of the tip as shown in FIGS. 1 and 2.

Regardless of the actual construction for the fitting of the part 6 of the guide sleeve 2 onto the tip 10 of the cap 9, in every embodiment the larger outside diameter of the tip fitting inside the part 6 of the guide sleeve produces a clamping action providing a very good hold. This is also true when instead of a raised surface as with a complementary taper or an outer ridge, only point-like bumps are provided. It is also worth mentioning that the flexibility of the part 6 compensates out manufacturing tolerances, making production easier.

Claims

1. A device for drawing body fluids, the device comprising a specimen tube (1) having at a outer end a tip (10) with a pierceable plug for a guide sleeve (2) fittable on the tip (10) and provided on its side turned toward the tip (10) with a needle (5) and with an elastomeric needle-shield tube (3) and on the side turned away from the tip with a connection fitting or the opposite end of a double needle, characterized in that the guide sleeve (2) is made of a relatively stiff material and has on its outer end adjacent a grip region (8) a resilient part (6), the tip (10) having a connection region of larger diameter than an inside diameter of the guide sleeve (2), the larger-diameter region of the tip spreading the resilient part (6) such that it solidly grips the tip (10) in a use position.