SYRINGE FOR OBTAINING A TARGET VOLUME OF BLOOD

Abstract

A syringe for obtaining a target volume of blood is presented. The syringe (1) comprises a barrel (2), wherein a plunger (4) is arranged within the barrel (2) to be displaceable along a displacement direction (X). Furthermore the barrel (2) and the plunger (4) together provide for a first stop (20) and second stop (22), wherein the first stop (20) is configured for positioning a filter (100) at a predetermined location along the displacement direction (X) thereby defining a target volume of blood and a buffer volume. Moreover, the second stop (22) is configured to stop the plunger (4) from expelling more than the buffer volume from the syringe (1) for obtaining the target volume of blood when the plunger (4) is pushed towards the distal end (30) of the syringe (1) along the displacement direction (X). In addition, the syringe (1) facilitates that the syringe (1) fills itself with the target volume of blood by a self-filling procedure using blood that is under pressure, like arterial blood, and using the filter (100) located in the plunger (4).

Claims

1. A syringe for obtaining a target volume of blood, the syringe comprising: a barrel, wherein a plunger is arranged within the barrel to be displaceable along a displacement direction, wherein the plunger comprises a filter, wherein the barrel and the plunger together provide for a first stop and a second stop, wherein the first stop is configured for positioning the filter at a predetermined location along the displacement direction thereby defining a target volume of blood and a buffer volume of blood, wherein the second stop is configured to stop the plunger from expelling more than the buffer volume for obtaining the target volume of blood when the plunger is pushed towards a distal end of the syringe along the displacement direction, wherein the barrel comprises a proximal end at which a first opening for introducing the plunger into the barrel is located, wherein at the distal end of the barrel a second opening for receiving the target volume of blood is located, and wherein the second stop is located closer to the first opening than the first stop, wherein the filter is configured to be gas-permeable when the filter is not in contact with blood, and wherein the filter is configured to become gas-impermeable when getting in contact with blood, wherein the plunger is fluid-sealing when the filter is gas-impermeable, and wherein the plunger is configured for guiding air out of the barrel and through the filter towards outside the syringe during a self-filling process of the syringe.

2. The syringe according to claim 1, wherein the plunger comprises a channel, wherein the filter is positioned inside the channel, and wherein the channel is configured for guiding the air out of the barrel and through the filter towards outside the syringe during the self-filling process of the syringe.

3. The syringe according to claim 1, wherein the channel has a first aperture at a proximal end of the plunger, wherein the channel has a second aperture at a distal end of the plunger, wherein the filter is located at least partially inside the channel and in-between the first aperture and the second aperture of the channel, wherein the filter is configured for ventilating gas through the channel of the plunger, when the filter is gas-permeable, and wherein the filter is configured for sealing the channel of the plunger fluid-tightly, when the filter is gas-impermeable.

4. The syringe according to claim 1, wherein the syringe comprises a ventilation tip cap on a tip of the syringe, wherein the ventilation tip cap is configured for preventing air from moving through the tip into the syringe, and wherein the ventilation tip cap is configured for allowing air to be pushed from inside the syringe, particularly the barrel, out of the syringe through the ventilation tip cap when the plunger is moved from the first stop to the second stop.

5. The syringe according to claim 1, wherein the first and/or the second stop define a stopping function along the displacement direction, wherein the stopping function is generated by form fit, friction fit, and/or adhesion between the plunger and the barrel.

6. The syringe according to claim 1, wherein the plunger comprises a first protrusion, in particular on the surface of the plunger, wherein the barrel comprises a second protrusion on an internal surface of the barrel, wherein the second protrusion and the first protrusion together form the first stop, wherein the plunger comprises a third protrusion, wherein the barrel comprises a cone on an internal surface of the barrel at the first opening, and wherein the third protrusion and the cone together form the second stop.

7. The syringe according to claim 6, wherein the internal surface of the barrel has an at least mainly constant diameter along the displacement direction and is configured to store a liquid, and wherein the first, second and/or third protrusion extend continuously around the barrel and/or the plunger.

8. The syringe according to claim 1, wherein the internal surface of the barrel forms a cone which extends radially around the displacement direction and is configured to orientate the plunger into the inner contour, when inserting the plunger into the barrel.

9. The syringe according to claim 1, wherein the barrel has an at least partially constant diameter, wherein a ratio between the diameter and a maximum displacement length along the displacement direction is from 1:1.5 and 1:8.

10. A method of filling a syringe with a target volume of blood, the method comprising: providing a syringe comprising: a barrel, wherein a plunger is arranged within the barrel to be displaceable along a displacement direction, wherein the plunger comprises a filter, wherein the barrel and the plunger together provide for a first stop and a second stop, wherein the first stop is configured for positioning the filter at a predetermined location along the displacement direction thereby defining a target volume of blood and a buffer volume, and wherein the second stop is configured to stop the plunger from expelling more than the buffer volume for obtaining the target volume of blood when pushed towards a distal end of the syringe along the displacement direction, guiding blood into the syringe causing air to move from the barrel through the filter of the plunger towards outside of the syringe as long as the filter is not in contact with blood, -causing a contact of the blood with the filter thereby changing the permeability of the filter from being gas-permeable when the filter is not in contact with blood to being gas-impermeable when getting into the contact with blood, and fluid tightly sealing the plunger by changing the permeability of the filter into being gas-impermeable.

11. The method according to claim 10, wherein the method further comprises: pushing air from inside the syringe, out of the syringe through a tip of the syringe by moving the plunger from the first stop to the second stop.

12. A package comprising a syringe according to claim 1, wherein the plunger (4) is positioned at the first stop (20).

13. A method comprising: providing a syringe according to claim 1; and obtaining blood from a human or animal using the syringe.

14. The syringe according to claim 8, wherein the cone is formed at the first opening of the barrel.

15. The method according to claim 11, wherein air is pushed from the barrel.

16. The method according to claim 11, wherein air is pushed through a ventilation tip cap of the syringe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG. 1 shows a cross-sectional view of the syringe according to a first embodiment.

[0065] FIG. 2 shows a cross-sectional view of a syringe according to a second embodiment.

[0066] FIG. 3 shows a flow chart illustrating the steps of a method according to an embodiment.

[0067] FIG. 4 shows a flow chart illustrating the steps of a method according to an embodiment.

[0068] The reference symbols used in the drawings, and their meanings, are listed in summary form in the list of reference symbols. In principle, identical parts are provided with the same reference symbols in the Figures.

DETAILED DESCRIPTION OF EMBODIMENTS

[0069] FIG. 1 shows a syringe 1 of the present invention. The syringe 1 comprises a plunger 4. The plunger 4 guarantees a minimal and/or recommended amount of blood obtained by the syringe 1 due to its geometrical extensions relative to the barrel 2 and is easy to use since the length of the pushing of the plunger 4 is minimized and/or limited since the second stop 22 limits the displacement of the plunger 4 towards the distal end 30. The plunger 4 comprises a shorter extension length 152 than the extension length 150 of the barrel. In other words, the barrel 2 comprises a first extension length 150 and the plunger 4 comprises a second extension length 152. The second extension length 152 is shorter than the first extension length 150. When the plunger 4 is pushed from first stop 20 to the second stop 22 venting of the syringe is performed, preferably with a ventilation tip cap 200 attached on the distal end 30. Since the plunger 4 is short, the push needed is small/short which makes using the syringe 1 easy. The syringe 1 comprises a barrel 2 and a plunger 4, which is arranged within the barrel 2 to be displaced along a displacement direction X. The barrel 2 and the plunger 4 together provide for the first 20 and the second 22 stop. The first stop 20 is configured for positioning the filter 100 at a predetermined location along the displacement direction X to define the target volume and a buffer volume of blood. The second stop 22 is configured to stop the plunger 4 from expelling more than the buffer volume of blood for obtaining the target volume of blood when pushed a long the displacement direction X direction towards the distal end 30 of the syringe. This result in a syringe 1, which is capable of only obtaining the needed amount of blood, for example for a blood gas test, and thereby reduces stress for a patient. Additionally the first stop 20 within the syringe 1 improves the handling of the syringe 1, since a haptic feedback is generated by the first stop 20, when the needed amount of blood is obtained.

[0070] The plunger 4 comprises a channel 102, which extends through the plunger 4 along the displacement direction X. The plunger 4 further comprises a seal 104 which seals the surface of the plunger 4 against the inside surface of the barrel 2. With the help of the seal 104, the only way for air is to go through the channel 102 and the filter 100 of the plunger. The filter 100 is located inside the channel 102. The filter 100 is gas-permeable when the filter 100 is not in contact with blood and the filter 100 is fluid-sealing when the filter 100 is in contact with blood. The channel 102 comprises a first aperture 130, which can comprise a hand piece for manipulating the plunger 4. In addition, the channel 102 comprises a second aperture 132, which is located inside the barrel 2. In particular, air flows from the second aperture 132 to the first aperture 130 in order to be able to obtain blood in the barrel 2.

[0071] The syringe 1 of FIG. 1 is a preferred embodiment, wherein the plunger 4 comprises a first protrusion 10 of the plunger 4 and a third protrusion 6 of a plunger 4. Furthermore, the barrel 2 comprises a second protrusion 5. The first protrusion 10 of the plunger 4 and the second protrusion 5 of the barrel 2 are configured to form the first stop 20. Furthermore, the third protrusion 6 of the plunger 4 and a cone 24 on an internal surface of the barrel 2 at the first opening 28 are configured to form the second stop 22. Furthermore, the plunger 4 is located within the barrel 2 to be displaceable along a displacement direction X. A vertical direction Y is about orthogonal to the displacement direction X. The second protrusion 5 of the barrel 2, the first protrusion 10 of the plunger 4 and the third protrusion 6 of the plunger 4 all extend in this embodiment along the vertical direction Y. Furthermore, the first opening 28 of the barrel 2 is configured to orientate the plunger 4 into the barrel 2. Attached to the first opening 28, a cone 24 is provided which supports the orientation of the plunger 4 into the barrel 2. The first opening 28 is provided at the proximal end 26 of the barrel 2. At the distal end 30 of the barrel 2, a second opening 32 is foreseen. The second opening 32 is configured to be attached to a needle, a tip cap 200 or an access within a patient.

[0072] FIG. 2 shows an embodiment of the syringe 1. The plunger 4 comprises a plunger top 106, which is configured for holding the seal 104 in order to fluid tightly seal the barrel 2 towards the inner surfaces of the barrel. In addition, the plunger 4 comprises a third protrusion 6, which is formed by an extrusion of the plunger 4. Thereby, the plunger 4 can comprise a hand piece for easy use of the syringe 1 and the third protrusion 6 for forming a part of the second stop 22. Furthermore, the syringe 1 comprises a ventilation tip cap 200. The ventilation tip cap 200 is attachable to the syringe 1. After the syringe 1 has been filled with blood and is detached from a patient, the ventilation tip cap 200 is attached to the syringe. With the attached ventilation tip cap 200, the plunger 4 is pushed towards the ventilation tip cap 200 until the third protrusion 6 reaches the cone 24 and thereby forms the second stop 22. By this push, the ventilation tip cap 200 assures that air is removed from the syringe 1 and the target amount of blood is still in the syringe 1.

[0073] FIG. 3 shows a flowchart illustrating the steps of the method according to an embodiment. The method comprises the step of providing S1 a syringe, in particular a syringe as described before and hereinafter. In addition, the method comprises the step of guiding S2 blood into the syringe 1, causing air to move from the barrel 2 through the filter 100 of the plunger 4 towards outside of the syringe 1 as long as the filter 100 is not in contact with blood. Furthermore, the method comprises the step of causing S3 a contact of the blood with the filter 100 thereby changing the permeability of the filter 100 from being gas-permeable when the filter 100 is not in contact with blood to being gas-impermeable when getting into the contact with blood. In addition, the method comprises the step fluid tightly sealing S4 the plunger 4 by changing the permeability of the filter 100 into being gas-impermeable. In other words, the syringe 1 can be attached to a patient, when the plunger 4 is located at the first stop 20. The plunger 4 at the first stop 20 can form a volume within the barrel 2, which can comprise the target volume of blood and the buffer volume. Blood can enter the barrel 2 and air located in the barrel 2 can be pushed out of the syringe 1 through the filter 100. When the target volume of blood and the buffer volume is inside the barrel 2 the filter 100 becomes gas impermeable.

[0074] FIG. 4 shows a flowchart illustrating the steps of a method according to an embodiment. The method comprises the steps of providing S1, guiding S2, causing S3 and fluid tightly sealing S4. In addition, the method may comprise the step of pushing S5 air from inside the syringe 1, particularly the barrel 2, out of the syringe 1 through a tip of the syringe 1, and preferably through a ventilation tip cap 200, by moving the plunger 4 from the first stop 20 to the second stop 22. In other words, a ventilation tip cap 200 can be attached to the syringe. The ventilation tip cap 200 is configured for releasing air out of the syringe 1 and for assuring that the target volume of blood remains in the syringe 1, when pushing S5 the air out of the syringe. The air can be removed from the inside of the syringe by pushing the plunger 4 against the second stop 22. Thereby the volume inside the barrel 2 is reduced such that the buffer volume is removed and only the target volume of blood remains inside the syringe 1.

[0075] Where an indefinite or definite article is used when referring to a singular noun, e.g. “a”, “an” or “the”, this includes a plurality of that noun unless something else is specifically stated. The terms “about” or “approximately” in the context of the present invention denote an interval of accuracy that the person skilled in the art will understand to still ensure the technical effect of the feature in question. The term typically indicates deviation from the indicated numerical value of ±22%, preferably ±15 %, more preferably ±10%, and even more preferably ±5%.

[0076] Furthermore, the terms “first”, “second”, “third” or “(a)”, “(b)”, “(c)”, “(d)” or “(i)”, “(ii)”, “(iii)”, “(iv)” etc. and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

REFERENCE SIGNS

[0077] 1 - syringe [0078] 2 - barrel [0079] 4 - plunger [0080] 5 - second protrusion [0081] 6 - third protrusion [0082] 10 - first protrusion [0083] 20 - first stop [0084] 22 - second stop [0085] 24 - cone [0086] 26 - proximal end [0087] 28 - first opening [0088] 30 - distal end [0089] 32 - second opening [0090] 100 - filter [0091] 102 - channel [0092] 104 - seal [0093] 106 - plunger top [0094] 130 - first aperture [0095] 132 - second aperture [0096] 150 - first extension length [0097] 152 - second extension length [0098] 200 - ventilation tip cap [0099] X - displacement direction [0100] Y - vertical direction [0101] S1 -providing [0102] S2 - guiding [0103] S3 - causing [0104] S4 - fluid tightly sealing [0105] S5 - pushing