DEVICE FOR CONNECTING A CANNULA TO A CONTAINER

Abstract

The invention relates to a device for connecting a cannula to a container under reduced pressure, in particular a blood culture flask, including an inflow opening for connecting to the cannula or to a connection tube connected to the cannula, an outflow opening for connecting to a hollow pin for piercing a closure of the container, and a tight fluidic connection of the inflow opening to the outflow opening. According to the invention, a reservoir which is separated from the fluidic connection and contains a specified gas quantity is connected to the fluidic connection with the interposition of a valve which is preferably open towards the fluidic connection.

Claims

1-21. (canceled)

22. A device for connecting a cannula to a container under reduced pressure, comprising: an inflow opening configured to connect to one of the cannula and a connecting tube leading to the cannula; an outflow opening configured to connect with a hollow mandrel configured to pierce a closure of the container; and a tight fluidic connection of the inflow opening with the outflow opening; wherein a reservoir that contains a predetermined quantity of gas and that is separate from the fluidic connection is connected to the fluidic connection with the interposition of a valve.

23. The device according to claim 22, wherein: the container is a blood culture bottle; and the valve opens towards the fluidic connection.

24. The device according to claim 22, wherein the outflow opening is integrally connected to the hollow mandrel.

25. The device according to claim 22, wherein the quantity of gas in the reservoir is at atmospheric pressure and occupies a volume of 40 cm.sup.3 to 100 cm.sup.3.

26. The device according to claim 22, wherein the valve is switchable by a differential pressure prevailing between the reservoir and the fluidic connection.

27. The device according to claim 22, wherein the valve is openable by a negative pressure prevailing in the fluidic connection.

28. The device according to claim 22, wherein the valve is closable by an overpressure prevailing in the fluidic connection.

29. The device according to claim 22, wherein a chamber is arranged on a side of the valve that is connected to the fluidic connection, so that an overpressure prevailing in the chamber acts on a valve closure member of the valve in a closing direction.

30. The device according to claim 29, wherein the reservoir has a perforated plate with at least one hole as a reservoir wall and the at least one hole is covered by the valve closure member of the valve in a closed position of the valve on a side facing to the chamber.

31. The device according to claim 30, wherein the perforated plate is circular.

32. The device according to claim 22, wherein the reservoir is formed as an annular chamber surrounding the fluidic connection.

33. The device according to claim 32, wherein the perforated plate supports the fluidic connection.

34. The device according to claim 29, wherein the valve closure member is designed as a circular, deformable disc with a valve hole.

35. The device according to claim 34, wherein the valve hole is centrally formed.

36. The device according to claim 30, wherein: the perforated plate and a wall of the chamber opposite the perforated plate bear against the valve closure member at an edge thereof; and in a region of the valve hole, a wall of the chamber opposite the perforated plate is spaced apart from the valve closure member.

37. The device according to claim 30, wherein the perforated plate and the wall of the chamber opposite the perforated plate bear against the valve closure member at an edge thereof in a clamping manner.

38. The device according to claim 29, wherein the valve closure member is made of a material selected from the group consisting of rubber, silicone and polyolefins.

39. The device according to claim 22, wherein the valve is configured to open at a negative pressure of the fluidic connection with respect to the reservoir of 0.3 bar to 0.8 bar.

40. The device according to claim 22, wherein the valve is designed to close at an overpressure of the fluidic connection with respect to the reservoir of 0.1 bar to 0.4 bar.

41. A method of connecting a cannula to a container under reduced pressure, comprising: providing a connecting device for connecting the cannula to the container being under reduced pressure, in particular a connecting device according to claim 22; connecting the connecting device to the cannula and to the container that is under reduced pressure, thereby establishing a fluidic connection from the cannula to the container; and drawing a quantity of gas from a reservoir of the connection device, which is separate from the fluidic connection, into the container, said drawing being effected by a negative pressure prevailing in the container relative to the reservoir.

42. The method according to claim 41, wherein the container is a blood culture bottle.

43. The method according to claim 41, wherein said drawing of the quantity of gas from the reservoir into the container is carried out until one of a complete and a partial pressure equalization between the reservoir and the container.

44. The method according to claim 41, wherein said drawing of the gas quantity from the reservoir into the container takes place via a valve arranged between the reservoir and the fluidic connection.

45. The method according to claim 41, wherein the reservoir is filled with a predetermined quantity of gas, which is dimensioned in such a way that the pressure prevailing in the container is increased by 30%-100%.

46. The method according to claim 41, wherein a predetermined amount of gas is provided in the reservoir at atmospheric pressure and having a volume of 40 cm.sup.3 to 100 cm.sup.3.

47. The method according to claim 41, wherein, after the amount of gas is drawn from the reservoir into the container, a liquid is drawn from the cannula into the container via the fluidic connection.

48. The method according to claim 47, wherein said drawing of the liquid from the cannula is performed by a negative pressure prevailing in the container with respect to the liquid pressure in the cannula.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The invention is explained in more detail below with reference to an example of an embodiment shown in the drawing. Therein,

[0048] FIG. 1 shows a longitudinal section through a device according to the invention,

[0049] FIG. 2 shows a perspective view of the longitudinal section according to FIG. 1,

[0050] FIG. 3 shows a schematic representation of the device according to the invention during pressure equalization and

[0051] FIG. 4 shows a schematic representation of the device according to the invention after pressure equalization.

DETAILED DESCRIPTION

[0052] In FIG. 1, a device according to the invention for connecting a cannula to a container being under reduced pressure is generally designated by the reference sign number 1. The device 1, also referred to as adapter has an inflow line 2 with an inflow opening 2′ and a connection 3 for a cannula not shown in FIGS. 1 and 2 or a connecting tube for a cannula. Furthermore, the device 1 has an outflow line 4 with an outflow opening 4′, to which a hollow mandrel not shown in FIGS. 1 and 2 can be connected for piercing a blood culture bottle. A chamber 5 is arranged between the inflow line 2 and the outflow opening 4′, which has an exceedingly small volume and connects the inflow line 2 with the outflow line 4 in a sealing manner. The inflow line 2, the chamber 5 and the outflow line 4 form a fluidic connection between the inflow opening 2′ and the outflow opening 4′.

[0053] With the interposition of a valve 6, which in this example is essentially formed by a valve closure member 6′ covering a plurality of holes 7 in a perforated plate 8, a reservoir 9 is connected to the chamber 5, in which a certain amount of gas is preferably present at atmospheric pressure. The volume of the reservoir 9 is, for example, 70 cm.sup.3. The perforated plate forms both a wall of the chamber 5 and a wall of the reservoir 9.

[0054] Furthermore, it can be clearly seen in FIG. 1 that the perforated plate 8 and a wall 10 of the chamber 5 opposite the perforated plate 8 bear against the valve closure member 6′ at its edge 11 in a clamping manner and thus support the valve closure member 6′. In the area of the valve hole 12, the wall 10 of the chamber 5 opposite the perforated plate 8 is spaced from the valve closure member 6′ to allow movement of the valve closure member in the sense of the double arrow 13.

[0055] In FIG. 2, in which the same parts are provided with the same reference numerals, which incidentally also applies to all other figures, it can be seen that the holes 7 in the perforated plate 8 are covered by the valve closure member 6′ on the chamber 5 side in the closed position. Further, it can be seen that the perforated plate 8 centrally supports the inflow line 2 and the reservoir 9 surrounds the inflow line 2.

[0056] In the schematic representation according to FIG. 3, it can be seen that the valve closure member 6′ is deflected in the direction of arrow 14 by the effect of negative pressure or pressure reduced relative to atmospheric pressure in the container 15, for example a blood culture bottle 15, the closure 16 of which is pierced by a hollow mandrel 17, so that a certain amount of gas is drawn through the holes 7 from the reservoir 9 via the chamber 5 and the outflow line 4 into the container 15. Pressure equalization between chamber 5 and container 15 is done more or less complete, although the resistance or restoring tendency of the valve closure member 6′ will not permit perfect pressure equalization due to its material properties. However, the volumes are selected so that the negative pressure in the container 15 is matched to the level of the atmosphere or to the pressure in a blood vessel of a patient to such an extent that only a limited volume of blood is drawn into the blood culture bottle 15. A cannula or a connecting tube to the cannula is designated by the reference numeral 18. A patient's blood vessel is not shown and is only illustrated by a vessel containing a fluid.

[0057] In FIG. 4, the valve closure member 6′ is again shown in the undeflected closed position abutting the holes 7 in the perforated plate 8, and the chamber 5 is filled with liquid. The amount of liquid, in the case of use of the device according to the invention blood, is a dead volume, so that the chamber 5 is designed with the smallest possible volume.