FLUID VESSEL INSERTION DEVICE WITH AUTOMATIC NEEDLE RETRACTION

Abstract

The present invention relates to a fluid vessel insertion device comprising a) a puncture member arranged for location within a cannulation sheet and comprising an interior lumen; b) a retractor arranged to actuate the puncture member relative to the cannulation sheet in use between i) a first situation in which a distal end of the puncture member protrudes beyond an end of the cannulation sheet, and ii) a second situation in which the distal end of the puncture member is within the cannulation sheet; c) a chamber in fluid communication with an exterior of the device only via the lumen and distal end of the puncture member; and d) a sheet of material located in the chamber to prevent the proximal end of the puncture member from moving; wherein the distal end of the puncture member is configured as a puncturing end having a distal n end opening for insertion into a fluid vessel when in use, and wherein the retractor triggers retraction of the puncture member between the first and the second situation automatically in response to wetting of the sheet of material by a fluid entering the puncture member lumen, whereby the sheet of material is comprising a material whose tensile strength is reduced upon contact with the fluid, and breaks under the pressure of the retractor.

Claims

1. A fluid vessel insertion device comprising a) a puncture member arranged for location within a cannulation sheet and comprising an interior lumen; b) a retractor arranged to actuate the puncture member relative to the cannulation sheet in use between i) a first situation in which a distal end of the puncture member protrudes beyond an end of the cannulation sheet, and ii) a second situation in which the distal end of the puncture member is within the cannulation sheet; c) a chamber in fluid communication with an exterior of the device only via the lumen and distal end of the puncture member; and d) a sheet of material located in the chamber to prevent the proximal end of the puncture member from moving; wherein the distal end of the puncture member is configured as a puncturing end having a distal opening for insertion into a fluid vessel when in use, and wherein the retractor triggers retraction of the puncture member between the first and the second situation automatically in response to wetting of the sheet of material by a fluid entering the puncture member lumen, whereby the sheet of material is comprising a material whose tensile strength is reduced upon contact with the fluid, and preferably breaks under the pressure of the retractor.

2. The device according to claim 1, wherein the sheet of material is comprising a wettable membrane, more preferably comprises cellulose or starch based membranes.

3. The device according to claim 1, wherein the sheet of material has a wet strength of less than 10%, preferably less than 8%.

4. The device according to claim 1, wherein of from 1 up to 8 sheets of material are stacked, more preferably of from 2 up to 5 sheets of material are stacked and are located in the chamber.

5. The device according to claim 1, wherein an opening is present in the side of the puncture member at a distance from the distal end.

6. The device according to claim 1, wherein an opening is present in the side of the cannulation sheet.

7. The device according to claim 1, wherein the retractor is a spring.

8. The device according to claim 1, wherein the sheet of material is fixed to the chamber, preferably fixed with a glue, more preferably fixed with a clinically approved glue.

9. The device according to claim 1, wherein the fluid vessel is a vein, preferably a blood vein.

10. A process for safely placing a cannulation sheet in a fluid vessel, whereby a device comprising a puncture member is used, the puncture member being arranged within the cannulation sheet, whereby the puncture member in the first situation protrudes beyond an end of the cannulation sheet, and whereby the puncture member automatically retracts to a safe position within the cannulation sheet upon contact with a fluid by wetting a sheet of material in a chamber, whereby the sheet of material is comprising a material whose tensile strength is reduced upon contact with the fluid, and breaks under the pressure of the retractor.

11. A process according to claim 10, wherein the fluid vessel is a vein, preferably a blood vein.

12. Use of a device according to claim 1 for placing a cannulation sheet into a fluid vessel, preferably a vein, more preferably a blood vein.

Description

[0037] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, wherein like letters and numerals refer to like parts, wherein the figures are approximately to scale, and wherein:

[0038] FIG. 1 illustrates an example of a fluid vessel insertion device in which the end of the puncture member protrudes beyond the end of the cannulation sheet;

[0039] FIG. 2 illustrates an example of a fluid vessel insertion device in which the end of the puncture member is within the cannulation sheet;

[0040] FIG. 3 illustrates an example of the punctuation device with a needle tip beyond the cannulation sheet with an opening in the punctuation device and in the cannulation sheet;

[0041] FIG. 4 illustrates an example of the punctuation device with a needle tip within the cannulation sheet with an opening in the punctuation device and in the cannulation sheet.

[0042] FIG. 5 shows the results of the comparison of the membrane tensile strength in dry and wet state of different sheets of cellulose membrane materials.

[0043] FIG. 6 shows the results of the comparison of the membrane layer thickness in dry and wet state, using an increasing number of sheet layers on top of each other.

[0044] FIG. 7 shows a comparison of the retraction speed of various sheets, numbered 1 to 9, of different cellulose membrane materials, following wetting.

[0045] The invention described below is about an automatic mechanism that causes withdrawal of the puncture device out of the fluid vessel once a cannulation sheet is correctly positioned for communication. In medical applications, for insertion of a cannulation sheet into for example a blood vessel, the device is triggered when the needle moved into the blood vessel and contact is being made with blood. This removes the need for the person handling the device to manually retract the needle upon determination of the correct location of the needle in the blood vessel or vein. The automation of this part of the handling prevents a major cause of cannula insertion failure due to poor detection of the second wall of the blood vessel being punctured as well.

[0046] This invention may trigger automatic withdrawal of the puncture member, e.g. the needle, as soon as the cannulation sheet is inserted into the vessel based on the transport of the fluid through the needle wetting the wettable material outside of the vessel.

[0047] Whilst the invention finds particular use in the insertion of a cannulation sheet into one of the fluid vessels in the human body, it is not limited to vascular access applications and may be used in other instances where it is necessary to undertake such an operation with minimal loss of fluid and minimum discomfort of the patient where manual control of the operation is prone to potential failure.

[0048] It will be appreciated by the skilled person that the term “vessel” used herein may constitute a conduit, a cavity or a reservoir and should be construed accordingly.

[0049] Turning now to FIG. 1, this illustrates a first embodiment of an assembly (1) according to the invention, wherein the assembly (1) generally comprises a sleeve arrangement (2) attached via an attaching device (3) to housing (4). The sleeve arrangement (2) generally comprises a puncture member (5) and a cannulation sheet (6) attached to it, placed against a tapered wall (7). The sleeve arrangement (2) is connected via attaching device (3) to housing (4). The attaching device (3) is preferably a Luer taper. The Luer taper is a standardized system of small-scale fluid fittings used for making leak-free connections between a male-taper fitting and its mating female part on medical and laboratory instruments, including hypodermic syringe tips and needles or stopcocks and needles. Currently ISO 80369 governs the Luer standards and testing methods. Key features of Luer taper connectors are defined in the ISO 594 standards. There are two varieties of Luer taper connections: locking and slipping. Luer lock fittings are securely joined by means of a tabbed hub on the female fitting which screws into threads in a sleeve on the male fitting. Luer lock style connectors are divided into two types: one piece luer lock and two piece luer lock or rotating collar luer lock. One piece Luer lock comes as a single mold, and locking is achieved by rotating the entire luer connector or system. In two piece luer lock, a free rotating collar with threads is assembled to the luer and the locking is achieved by rotating the collar. Slip tip (Luer-slip) fittings simply conform to Luer taper dimensions and are pressed together and held by friction (they have no threads). Luer components are manufactured either from metal or plastic and are available from many companies worldwide. The attaching device (3) is more preferably a Luer taper of the locking type. The attaching device (3) is attached to housing (4) which comprises chamber (8). In chamber (8) the puncture member (5) with at the end a piston (9) with piston head (10) is present, as is a retractor (11) and a sheet of material (12). In the situation as presented in FIG. 1, the sheet of material (12) is in place and the retractor is in the initial position. The sharp end of the puncture member (5) is outside of the cannulation sheet (6) and can be used to puncture a fluid vessel. The retractor (11) is in a compressed position.

[0050] The sheet of material can be in any form, as long as the resistance of the material is decreased in such a way that the retractor can be moved in the longitudinal direction away from the direction of movement of the puncture member.

[0051] Turning to FIG. 2, it represents the situation were the sheet of material has been in contact with a fluid and is no longer withholding piston head (10), and the retractor (11) is in expanded form.

[0052] FIG. 3 illustrates a preferred embodiment of the current invention, wherein an opening (13) is present in the side of the puncture member (5) and an opening (14) is present in the cannulation sheet (6). The openings are placed on top of each other, in the start situation.

[0053] FIG. 4 illustrates the preferred embodiment of the current invention with the retractor (not visible) in extended form, the puncture member (5) has been retracted. The openings (13) and (14) are no longer on top of each other. In an alternative preferred embodiment, an opening (13) is present in the side of the puncture member only, placed more to the tip of the puncture member, such that in the starting position the opening is not covered by the cannulation sheet.

[0054] In an alternative preferred embodiment, an opening (13) is present in the side of the puncture member, and the tip at the distal end of the puncture member is sealed off.

[0055] The function of the side opening is to create retarded retraction. The stream of fluid in the fluid vessel enters the piston head not immediately when the vessel is punctured, but only after the puncture member is at the position that fluid can reach the opening. The puncture member is in this situation delayed in its retraction, and the puncture member remains longer in the initial position. This might be needed in some special cases, where it takes longer to place the cannulation sheet in the fluid vessel. The position of the side opening (13) of the puncture member is relative to the lumen of the to be punctured vessel. The distance between the tip at the distal end and the opening is advantageously determined by the thickness of the to be punctured vessel. In general the opening is advantageously placed at such a distance that the tip of the distal end does not touch the second wall of the vessel but the opening is within the vessel.

[0056] The present invention furthermore relates to a process for safely placing a cannulation sheet in a vessel, whereby a device comprising a puncture member is used, the puncture member being arranged within the cannulation sheet, whereby the puncture member in the first situation protrudes beyond an end of the cannulation sheet, and whereby the puncture member automatically retracts to a safe position within the cannulation sheet upon contact with a fluid by wetting a sheet of material in a chamber, whereby the sheet of material is comprising a material whose tensile strength is reduced upon contact with the fluid, and breaks under the pressure of the retractor.

[0057] The present invention also relates to the use of the device for safely inserting a cannulation sheet into a fluid vessel.

[0058] The following, non-limiting examples are provided to illustrate the invention. The use of sheets of wettable material is illustrated. As all samples were confidential, only sample numbers have been given. All samples comprised cellulose membrane materials in various compositions.

Example 1

[0059] To assess the effectiveness of cellulose paper membranes, the properties with respect to tensile strength were tested using a number of different cellulose membrane materials. The tensile strength is important in the dry state to withhold the needle when pushing it through a tissue, e.g. the skin, and in the wet state it is preferably as low as possible so that a needle easily breaks through the material. Membrane properties were assessed in its dry (top data point) versus its wetted (bottom data point) state. The results of the tests are summarized in FIG. 5. Both a single sheet of cellulose paper membrane (the left dot for a material in the figure) and 4 sheets (the right dot for a material in the figure) on top of each other were tested. A piston was driven through the membranes at 50 mm.Math.min, using a custom made probe burst set-up. The ultimate tensile strength was recorded. All experiments and iterations were performed in triplicate. Wetting the sheets was performed using 10 microliter of a phosphate buffered saline (PBS), which osmolarity and ion concentrations of the solution match those of the human body. Glycerol was added to the solution to mimic the viscosity of blood. As can be concluded from FIG. 5, different sheets of cellulose membrane materials give different results. Furthermore, the use of 4 layers of sheets is preferred over the use of 1 sheet, as the difference of tensile strength in this set-up between a dry and a wetted material is bigger.

Example 2

[0060] Using the same set up and conditions as described in example 1, the number of sheets was tested using sample number 2, a cellulose membrane material. The results are given in FIG. 6. As can be seen from FIG. 6, the tensile strength decreases upon wetting for all the number of sheets used, with the biggest difference of tensile strength between dry and wetted state with 4 layers of sheet material.

Example 3

[0061] Besides tensile strength, also the retraction speed is a factor that might be optimized. The retraction speed of the needle was assessed with various compositions of membranes. A custom made needle retraction device was placed in the pressure sensor of the tensile tester. The needle was primed using a membrane, and driven through a shore A60 silicone tube (wt:3 mm, ID: 6 mm) at a constant speed of 330 mm.Math.min. The start coordinates of the system were known and recorded. The silicone lumen was filled with PBS with glycerol at 100 mmHg. The needle was allowed to puncture the silicone, causing fluid to enter the needle and induce retraction of the needle. The tensile tester software recorded the increase in pressure as the needle entered the silicone, as well as the drop in resistance following retraction, allowing the retraction speed to be determined. The results are given in FIG. 7. It can be concluded that the various sheets of cellulose membrane give various results and depending on the retraction speed designed, a material can be chosen.