GB2436527A

GB2436527A - Needle having first and second hub openings controlled via valve

Info

Publication number: GB2436527A
Application number: GB0606292A
Authority: GB
Inventors: Zsolt Joel Szarka
Original assignee: PRO OPTIMA Ltd
Current assignee: PRO-OPTIMA LTD.
Priority date: 2006-03-29
Filing date: 2006-03-29
Publication date: 2007-10-03
Anticipated expiration: 2026-03-29
Also published as: WO2007110643A1; GB0606292D0; GB2436527B

Abstract

A needle comprises hub 6 and cannula 4, the hub defining a cavity in fluid communication with a lumen of the needle cannula. Hub 6 comprises plural, first and second, openings 32, 33 connected alternatively with the cavity via valve 30. The openings may provide an end port 10 and angled (e.g. 45 degree) side port 12, with Luer type connection fittings. Either opening may comprise a valve seat; valve 30 can be a flexible, living hinge, or rigid element with flexible peripheral seal. The needle may be a spinal needle (pencil point or lancet) with diameter not greater than 24G and not less than 33G, for example for anaesthesia injection into the cerebro-spinal fluid (CSF). A syringe may be removably connected to side port by a fitting or via a flexible conduit. The device may form part of a kit, along with an introducer needle.

Description

NEEDLE

This invention relates to a needle and particularly but not exclusively relates to a spinal needle for use in regional spinal anaesthesia.

S

BACKGROUND

Spinal anaesthesia involves the direct injection of small amounts of local anaesthetic into the cerebro-spinal fluid (CS F) within the subarachnoid space of the spine. A spinal needle is passed through the skin and outer tissues of a patient, including those of the epidural space, and is used to puncture the dura mater, delivering anaesthetic to the intrathecal compartment. The advantages of spinal anaesthesia are well documented and include rapid onset of block, anaesthetic efficiency and reduced cost when compared with that of general anaesthesia.

The equipment required for spinal anaesthesia is illustrated in Figure 1 and includes a spinal needle 100, ideally of 24G to 33G with either a pencil or lancet point tip, a stylet 102 to occupy the lumen of the needle during insertion, an introducer needle 104 to direct the flexible spinal needle, and a syringe 106 to hold the spinal anaesthetic solution. Once the patient has been prepared, the introducer needle 104 is inserted into the lumbar region of the spine and is advanced into the intraspinous ligament. The spinal needle 100, with the stylet 102 in place, is then inserted through the introducer needle 104, past the ligamentum flavum and epidural space, and punctures the dura mater to enter the subarachnoid space. If the needle 100 is correctly inserted, CSF flows into the cannula 110 of the spinal needle and appears in the transparent hub 108 of the needle 100. The stylet 102 is typically closely received in the needle cannula hindering the flow of CSF into the needle. It may therefore take some time for CSF fluid to be observed flowing into the hub. Once unobstructed CSF flow is observed, the stylet 102 is removed from the spinal needle 100, and the syringe 106 containing anaesthetic fluid is attached to the hub 108 of the spinal needle 100. Attachment is typically achieved by means of a Luer Lock or similar mechanical connection. The anaesthetic fluid may then be injected into the intrathecal compartment. When the injection is complete, the spinal needle 100, introducer needle 104 and syringe 106 are withdrawn as one.

A common problem encountered during spinal anaesthesia is accidental displacement of the needle tip. This may be in the form of accidental removal of the needle tip from the subarachnoid space, or over insertion of the needle leading to puncture of the distal wall of the dura. The delay in CSF flow that is commonly experienced when using small diameter needles often leads to spinal needles being inserted deeper within the subarachnoid space than is strictly necessary. In the case of such deeply inserted needles, the additional force that is often exerted on the needle during attachment of the syringe may be sufficient to force the tip of the needle through the distal wall of the d ura.

If the needle tip is dislodged from the correct position, either by removal or over insertion, some or all of the spinal anaesthetic may be injected outside the intrathecal compartment, resulting in only a partial block and failure of the procedure. Further, movement of the needle tip within the subarachnoid space can result in additional tearing of the dura mater leading to undesirable CSF leakage and Post Dural Puncture Headache (PDPH). Even if the dislodged tip is recognised by the anaesthetist and corrected, repositioning of the needle tip is difficult and often results in obstruction of the cannula and multiple punctures of the dura, increasing the likelihood of PDPH.

The chance of dislodging the spinal needle during a spinal anaesthetic procedure is increased when using very fine spinal needles. Spinal needles of 24G or smaller are preferred in order to minimise damage to the dura mater during puncture. However, such fine needles are flexible and difficult to manipulate with accuracy. An introducer needle is commonly used in connection with fine gauge spinal needles in order to aid direction. The disadvantage of such needles is that they reduce the amount of direct contact between the tissues of the body and the spinal needle cannula, thus reducing the stabilising friction force that holds the needle in place and helps to withstand accidental movement of the needle.

Accidental displacement of the spinal needle tip can occur at any time as a result of stress or fatigue on the part of the anaesthetist. However, the problem is most likely to occur during connection of the syringe, when it is necessary to handle the needle while the needle tip remains within the intrathecal compartment. It is essential to ensure a firm connection between the syringe and the needle hub, as hyperbaric anaesthetic solutions are viscous and resistance to injections can be high. It is, therefore, easy to spill anaesthetic if care is not taken to ensure a firm connection.

SUMMARY OF INVENTION

According to the present invention, there is provided a needle comprising a hub and a cannula, wherein the hub defines a cavity that is in fluid communication with a lumen of the cannula, the hub comprising first and second openings and a valve, the first and second openings communicating alternately with the cavity via the valve.

The valve may be a rotary valve, such as a valve having a rotating valve element.

The first opening may comprise an end port, which may terminate in a connection fitting. The second opening may comprise a side port, which may also terminate in a connection fitting.

The second opening may comprise a valve seat, and the second opening may be sealed with the valve in a closed position.

The first opening may comprise a valve seat. The first opening may be sealed with the valve in an open position.

The valve may comprise a flexible element, which may be a flat sheet of material. The flexible element may be formed from rubber, a plastics material, or a synthetic compound such as neoprene. The valve may pivot about a line or thin strip of material that has a higher degree of flexibility than the remainder of the valve, such that the valve forms a living hinge. Alternatively, the valve may be formed from a rigid material and may pivot about a conventional hinged joint having a hinge pin.

The valve may further comprise a flexible sealing element around the periphery of the valve. The flexible sealing element may comprise silicone sheet material. The valve may be substantially planar and oval or ellipse in shape.

The valve may be biased to a closed position.

A central axis of the end port may be substantially coincident with the longitudinal axis of the cannula. A central axis of the side port may intersect the central axis of the end port.

The cavity of the hub may be substantially cylindrical.

The connection fittings may comprise Luer type fittings, such as Luer Lock fittings.

Alternatively, the connection fittings may comprise other, known mechanical interlock connections.

The needle may comprise a spinal needle. The needle diameter may be not greater than 24G and not less than 33G.

The cannula may have a pencil point. Alternatively, the cannula may have a lancet point.

According to another aspect of the present invention, there is provided a needle assembly comprising a needle as described in the present specification and a syringe.

The syringe may be removably connected to the side port by a connection fitting. The syringe may be removably connected to the side port via a flexible conduit. The flexible conduit may comprise small bore tubing. In the context of the present invention, "small bore tubing" is considered to be tubing having an internal diameter not greater than 2 mm. Suitable tubing may, for example, have an internal diameter falling in the range 0.5 mm to 1.5 mm, with the outer diameter in the range of 1 mm to 2.7 mm. The flexible conduit may be formed from lightweight material, for example a plastics material such as polyvinylchloride (PVC), or polyethylene or silicone.

The needle assembly may further comprise a stylet. The stylet may be closely received in the cannula of the needle and may extend through the hub cavity and out of the end port.

The stylet may comprise a handle having a connection fitting suitable for connection to the connection fitting on the end port.

According to another aspect of the present invention, there is provided a surgical kit of parts comprising a needle assembly as described in the present specification and an introducer needle.

The introducer needle diameter may be not greater than 1 8G and not less than 20G.

The side port of the needle of the present invention enables a syringe to remain remotely connected to the needle during the entire procedure without interfering with the use and subsequent removal of the stylet. Once CSF flow is observed and the stylet is removed, no further handling of the needle is necessary; the injection can be completed by simply depressing the plunger of the syringe. This is in contrast to the prior art devices, in which the syringe must be connected while the needle is in the patient, thus greatly increasing the chance of dislodging the needle tip and compromising the procedure. The needle of the present invention minimises the amount of handling required while the needle is within the patient, reducing the chances of accidentally dislodging the needle from the subarachnoid space.

The valve within the needle alternately seals either the side port or the end port of the needle hub. When the side port is sealed, anaesthetic fluid is contained within the side port, syringe and flexible conduit and the end port is open to receive the stylet, or to enable unobstructed CSF flow. When the end port is sealed, anaesthetic fluid may be injected through the needle hub and cannula into the intrathecal cavity without loss to the atmosphere. The nature of the valve enables remote operation of the valve, removing the need to manually open or close the valve and so further reducing the amount of necessary handling of the needle while the needle tip is within the intrathecal cavity.

For the purposes of the present specification, needle diameter is indicated by gauge according to the Stubs Iron Wire Gauge system.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a sectional view of a spinal needles assembly of the prior art.

Figure 2 is a sectional view of a spinal needle.

Figure 3 is a sectional view of a spinal needle with a side port removed for clarity.

Figure 4 is a sectional view of a spinal needle assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figures 2 to 4, a needle assembly comprises a spinal needle 2, having a cannula 4 and a hub 6. The hub 6 comprises a main body 8, that terminates in an end port 10, and a side port 12, that extends from the main body 8 at an angle a. End port 10 and side port 12 each terminate in female Luer Lock connection fittings 14, 16. A stylet (not shown) extends through the hub 6 to occupy a lumen of the cannula 4 of the needle 2. The stylet comprises a handle having a male Luer Lock connection fitting, suitable for connection with the female Luer Lock connection fitting 14 on the end port 10. Referring particularly to Figure 4, a syringe (not shown) is connected to the side port 12 via a tube 18. A proximal end of the tube 18 terminates in a male Luer Lock connection fitting 20, and a distal end of the tube 18 terminates in a female Luer Lock connection fitting 22. The connection fittings 20, 22 on the tube 18 connect with the female connection fitting 16 on the side port 12 and a male connection fitting (not shown) on the syringe.

Referring to Figure 2, the main body 8 of the hub 6 is cylindrical and formed of transparent material. The end port 10 is also cylindrical and is continuous with the main body 8. A longitudinal axis 24 of the mainbody 8 and end port 10 is coincident with a longitudinal axis 26 of the cannula 4. The side port 12 is cylindrical and has a cross sectional diameter identical to that of the main body 8 and end port 10. A longitudinal axis 28 of the side port 12 intersects the longitudinal axis 24 of the end port at an angle a, which may be of any appropriate value for a particular application. In the illustrated embodiment, the angle a is approximately 45 . The side port 12 may protrude some distance from the main body 8 (as shown) or may be formed substantially within the main body 8. A valve 30 alternately seals an opening 32, between the side port 12 and the main body 8, and an opening 33, between the end port 10 and the main body 8. In a first, closed position (illustrated in solid lines), the valve 30 is received in a valve seat 34, formed at the intersection of the side port 12 and the main body 8. In a second, open position (illustrated in broken lines), the valve 30 is received in a valve seat 36 that defines the intersection between the main body 8 and the end port 10. The valve 30 pivots about an axis 38 at the intersection of the side port 12 and the end port 10.

The valve 30 may be formed from a flexible sheet material such as, for example, natural rubber latex, silicone elastomeric fluoropolymer or polyurethane elastomer. If formed from a flexible material, the valve is preferably configured to have a thin strip of more flexible material along the axis 38. This strip of more flexible material forms a living hinge, about which the valve 30 is able to pivot. The hinge is formed to be as small as possible in order to aid sealing of the valve. However, the hinge must be large enough to provide stability to the valve and resist twisting forces.

Alternatively, the valve 30 may be formed from a rigid material and may pivot about a conventional hinge including a hinge pin. The valve 30 may include additional sealing material around the periphery of the valve in the form of silicone sheets or other flexible sealing material. The valve 30 is preferably oval or elliptical in shape in order to aid sealing of the side and end ports 12, 10. However, the valve 30 may have any appropriate shape as determined by the internal cross sections of the side port 12 and the main body 8 of the hub 6.

The tube 18 comprises a section of small bore, lightweight tubing which may, for example, by polyethylene tubing having an internal diameter of 1 mm and an external diameter of 2 mm. The small internal diameter minimises dead space within the system and the light weight material ensures that the tube exerts minimal distracting force on the needle, thus reducing inconvenience to the anaesthetist.

Referring to Figures 2 and 3, the spinal needle 2 may have any appropriate configuration of point, including a lancet point 40, as illustrated in Figure 2, or a pencil point 42, as illustrated in Figure 3. The cannula of the needle may have any desired rotational alignment with respect to the hub 6. In an embodiment having a pencil point 42, the hole 46 of the pencil point 42 may be aligned with the side port 12, such that the hole 46 is on the same side as the side port 12. However, the hole 46 of the pencil point may have any other desired alignment with respect to the side port 12.

Prior to use, the syringe is filled with an appropriate amount of spinal anaesthetic solution. The syringe is then connected to the tube 18 via the cooperating male and female Luer Lock fittings. Excess air is pumped out of the tube 18 to reduce dead space within the system. The tube 18 is connected to the side port 12 of the needle 2 via the connection fittings 20 and 16. A vacuum may be created in the tube 18 by withdrawing slightly the plunger of the syringe. This vacuum causes a pressure difference across the valve 30, effectively biasing the valve 30 to the closed position illustrated in solid lines in Figure 2. The syringe may then be rested on an appropriate surface prior to inserting the spinal needle 2. It will be noted that, if a pencil point needle is used, due to the alignment of the the hole 46 of the pencil point 42 and the side port 12, when the needle 2 is in the correct position for insertion into a patient, the side port 12 and associated tube 18 will be orientated towards the ground, thus asserting minimal distracting force on the needle 2.

In use, an introducer needle (not shown) is first inserted into a patient in accordance with established procedures. The spinal needle 2 is then inserted through the introducer needle until puncture of the dura mater is achieved. The needle is maintained in position until CSF flow is observed. Once unobstructed CSF flow is established, the stylet is removed from the needle 2. The positive pressure exerted on the valve 30 by the CSF in the hub contributes to the pressure difference biasing the valve 30 to the closed position. The spinal anaesthetic solution is then administered by depressing the plunger of the syringe. Depressing the plunger of the syringe increases the pressure on the side port side of the valve 30, until the pressure difference across the valve 30 is reversed and the positive pressure difference is sufficient to open the valve 30. With the valve 30 in the open position, the end port 10 is sealed allowing unobstructed flow of anaesthetic solution from the syringe through the tube 18, main body 8 and cannula 4. It will be noted that, due to the compressible nature of air, the removal of air from the tube 18 prior to commencing the procedure is important to enable the pressure increase caused by depression of the syringe plunger to be efficiently transmitted to the valve 30. Once the injection is complete, the spinal needle and introducer may be withdrawn from the patient as one.

Claims

CLAIMS

1 A needle comprising a hub and a cannula, wherein the hub defines a cavity that is in fluid communication with a lumen of the cannula, the hub comprising first and second openings and a valve, the first and second openings communicating alternately with the cavity via the valve.

2 A needle as claimed in claim 1, wherein the first opening comprises an end port.

3 A needle as claimed in claim 2, wherein the end port terminates in a connection fitting.

4 A needle as claimed in any one of the preceding claims, wherein the second opening comprises a side port.

A needle as claimed in claim 4, wherein the side port terminates in a connection fitting.

6 A needle as claimed in any one of the preceding claims, wherein the second opening comprises a valve seat.

7 A needle as claimed in any one of the preceding claims, wherein the second opening is sealed with the valve in a closed position.

8 A needle as claimed in any one of the preceding claims, wherein the first opening comprises a valve seat.

9 A needle as claimed in any one of the preceding claims, wherein the first opening is sealed with the valve in an open position.

A needle as claimed in any one of the preceding claims, wherein the valve comprises a flexible element.

11 A needle as claimed in claim 10, wherein the valve comprises a living hinge.

12 A needle as claimed in any one of claims 1 to 9, wherein the valve comprises a rigid element.

13 A needle as claimed in claim 12, wherein the valve comprises a hinge having a hinge pin.

14 A needle as claimed in any one of the preceding claims, wherein the valve further comprises a flexible sealing element around the periphery of the valve.

15 A needle as claimed in any one of the preceding claims, wherein the valve is substantially planar.

16 A needle as claimed in any one of the preceding claims, wherein the valve is biased to a closed position.

17 A needle as claimed in any one of claims 2 to 16, wherein a central axis of the end port is coincident with the longitudinal axis of the cannula.

18 A needle as claimed in claim 17, wherein a central axis of the side port intersects the central axis of the end port.

19 A needle as claimed in any one of the preceding claims, wherein the cavity of the hub is substantially cylindrical.

20 A needle as claimed in any one of claims 3 to 19, wherein the connection fittings comprise Luer type fittings.

21 A needle as claimed in any one of the preceding claims, wherein the needle comprises a spinal needle.

22 A needle as claimed in any one of the preceding claims, wherein the needle diameter is not greater than 24G and not less than 33G.

23 A needle as claimed in any one of the preceding claims, wherein the cannula has a pencil point.

24 A needle as claimed in any one of claims 1 to 22, wherein the cannula has a lancet point.

A needle assembly comprising a needle as claimed in any one of the preceding claims and a syringe.

26 A needle assembly as claimed in claim 25, wherein the syringe is removably connected to the side port by a connection fitting.

27 A needle assembly as claimed in claim 26, wherein the syringe is removably connected to the side port via a flexible conduit.

28 A needle assembly as claimed in claim 27, wherein the flexible conduit comprises tubing having an internal diameter not greater than 2 mm.

29 A needle assembly as claimed in any one of claims 25 to 28, further comprising a stylet.

A needle assembly as claimed in claim 29, wherein the stylet is closely received in the cannula of the needle and extends through the hub cavity and out of the end port.

31 A needle assembly as claimed in claim 29 or 30, wherein the stylet comprises a handle having a connection fitting suitable for connection to the connection fitting on the end port.

32 A surgical kit of parts comprising a needle assembly as claimed in any one of claims 25 to 31 and an introducer needle.

33 A surgical kit as claimed in claim 32, wherein the introducer needle diameter is not greater than 1 8G and not less than 20G.

34 A spinal needle substantially as described herein with reference to and as shown in Figures 2 and 3 of the accompanying drawings.

A spinal needle assembly substantially as descalbed herein with reference to and as shown In Figure 4 of the accompanying drawings.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS

I A needle assembly comprising a needle and a stylet, the needle comprising a hub and a cannula, wherein the hub defines a cavity that is in fluid communication with a lumen of the cannula, the hub comprising first and second openings and a closure element which is movable between a closed position, in which the first opening communicates with the cavity and the closure element isolates the second opening from the cavity, and an open position, in which the second opening communicates with the cavity and the closure element isolates the first opening from the cavity, the stylet being insertable into the lumen of the cannula through the first opening when the closure element is in the closed position.

2 A needle assembly as claimed in claim 1, wherein the first opening comprises an end port.

3 A needle assembly as claimed in claim 2, wherein a central axis of the end port is: * . coincident with the longitudinal axis of the cannula. * 4 A needle assembly as claimed in any one of the preceding claims, wherein the **.S second opening comprises a side port. **..

A needle assembly as claimed in claim 4 when appendant to claim 2, wherein a S...

central axis of the side port intersects the central axis of the end port. .. : 6 A needle assembly as claimed in any one of the preceding claims, wherein the cavity of the hub is substantially cylindrical.

7 A needle assembly as claimed in any one of claims 2 to 6, wherein the port, or at least one of the ports, terminates in a connection fitting.

8 A needle assembly as claimed in claim 6, wherein the or each connection fitting comprises a Luer type fitting.

9 A needle assembly as claimed in claim6 or 7 when appendant to claim 2, wherein the stylet comprises a handle having a connection fitting suitable for connection to the connection fitting on the end port.

A needle assembly as claimed in any one of the preceding claims, wherein a valve seat is provided at the second opening, the closure element engaging the valve seat of the second opening in the closed position.

11 A needle assembly as claimed in any one of the preceding claims, wherein a valve seat is provided at the first opening, the closure element engaging the valve seat of the first opening in the open position.

12 A needle assembly as claimed in any one of the preceding claims, wherein the closure element comprises a flexible element.

13 A needle assembly as claimed in claim 12, wherein the closure element is connected to the hub at a living hinge.

14 A needle assembly as claimed in any one of claims 1 to 11, wherein the closure: S...

element comprises a rigid element. * :.

A needle assembly as claimed in claim 14, wherein the closure element is S...

connected to the hub by a hinge having a hinge pin. S..... *.

16 A needle assembly as claimed in any one of the preceding claims, wherein a * ...

flexible sealing element is provided around the periphery of the closure element. .. : 17 A needle assembly as claimed in any one of the preceding claims, wherein the closure element is substantially planar.

18 A needle assembly as claimed in any one of the preceding claims, wherein the closure element is biased to the closed position.

19 A needle assembly as claimed in any one of the preceding claims, wherein the needle comprises a spinal needle.

A needle assembly as claimed in any one of the preceding claims, wherein the needle diameter is not greater than 24G and not less than 33G.

21 A needle assembly as claimed in any one of the preceding claims, wherein the cannula has a pencil point.

22 A needle assembly as claimed in any one of claims I to 21, wherein the cannula has a lancet point.

23 A needle assembly as claimed in any one of the preceding claims, further comprising a syringe.

24 A needle assembly as claimed in claim 23 when appendant to claim 7, wherein the syringe is removably connected to the side port by the connection fitting.

A needle assembly as claimed in claim 24, wherein the syringe is removably connected to the side port via a flexible conduit.

26 A needle assembly as claimed in claim 25, wherein the flexible conduit comprises tubing having an internal diameter not greater than 2 mm.

27 A surgical kit of parts comprising a needle assembly as claimed in any one of the S...

preceding claims, and an introducer needle. S.... S...

28 A surgical kit as claimed in claim 27, wherein the introducer needle diameter is ** S...

not greater than 1 8G and not less than 20G. ..* : 29 A spinal needle substantially as described herein with reference to and as shown in Figures 2 and 3 of the accompanying drawings.

A spinal needle assembly substantially as described herein with reference to and as shown in Figure 4 of the accompanying drawings.