WO2006046029A2

WO2006046029A2 - Improved needle

Info

Publication number: WO2006046029A2
Application number: PCT/GB2005/004126
Authority: WO
Inventors: Malcolm John Watson; George A. Corner; Katherine J. Kirk; Alexander Cochrane
Original assignee: Greater Glasgow Health Board
Priority date: 2004-10-26
Filing date: 2005-10-26
Publication date: 2006-05-04
Also published as: GB0423741D0; WO2006046029A3

Abstract

An improved needle for use in ultrasound guided techniques and administration of regional and/or local anaesthetic is described. The improved needle has a substantially cylindrical shaft having a proximal and distal end, with the distal end being cut substantially perpendicular to the longitudinal axis. In one embodiment the improved needle is provided with an internal protrusion which deflects the path of a catheter inserted through the needle. A further embodiment is provided with wings which can be attached to a support member provided with the needle in alternative first and second directions. A further embodiment is provided with a blinder which protrudes at the distal end of the needle and is designed to assist puncturing of the tissue. Embodiments of the improved needle which are echogenically enhanced and a needle assembly are also described.

Description

Improved Needle

The present invention relates to an improved needle, and in particular an improved needle for use in the administration of regional and/or local anaesthesia and for use in ultrasound guided techniques.

It is common to provide a patient with regional anaesthetic, for example into the sub-arachnoid or dural space either directly or via a catheter. The purpose of such an injection may be to provide analgesia or anaesthesia to control pain or allow a surgical procedure to be undertaken, respectively. Such administration of anaesthesia may be referred to as epidurals, peridurals, peripheral nerve blocks, plexus blocks, or central neuroaxial blocks.

In order to administer effectively the anaesthetic into the patient via a catheter, it is conventional to use a tuohy needle or another blunt ended. A conventional tuohy needle is illustrated in accompanying Figures IA, IB and 2. Figure IA shows the tuohy needle 10 from a perspective view. The needle 10 comprises a cylindrical needle shaft 12, made from stainless steel, with a smooth outer edge. The needle is provided with a plastic moulded support member 14 at its proximal end 15. The plastic support member 14 has mounted thereto a plastic planar member 16 defining a pair of wings 17. The wings 17 function as bracing or gripping members to provide the user with control over the needle during insertion. The plastic planar member is elongate in one direction which extends across the main axis of the needle.

A plastic hub 18 is located behind the wings 17 to allow threading of a catheter through the needle. Once the catheter is in place, the needle is removed, and a syringe is attached to the catheter. Local anaesthetic can subsequently be injected into the patient's extradural space via the epidural catheter.

The needle is provided with a "blinder" 19 (or stilette) , which is a core of plastic that fits the inside of the needle and which is retained in the needle during insertion in order to avoid "coring" of the flesh by the needle.

The plastic moulded support member 14 of the needle has a pair of plates 20 defining a groove 21. The plastic planar member has a portion removed for receiving the plastic support member. The end member can therefore be placed over the plastic support member at the groove 21, at which it is clipped into place. The wings 17 are prevented from axial movement by the two plates. Figure IB shows the tuohy needle in its dissembled state, with the wings removed, to allow packaging of the needle in a compact form.

The needle is formed with an elongate opening, and curved tip designed to direct the catheter either cranially or cordially within the epidural space. Anaesthetists believe that ideally, when administering epidurals, catheters should lie cranially up the epidural space.

Figure 2 shows a close-up of the distal end 13 of the needle 10 in longitudinal-section. The distal end of the needle is provided with a blunt (ie non-cutting) tip, which is upturned from the lower edge 22 of the needle. This upturned tip 23 partially guides a catheter inserted through the needle in an upward direction.

The currently available design of tuohy needle suffers from a number of drawbacks and disadvantages.

Firstly, the orientation of the wings 17 with respect to the catheter-directing curve 23 requires the anaesthetist to insert the needle with his hand in the fully pronated or supinated position. This position limits the control that the anaesthetist has over the needle.

The upturned opening of the needle tip also presents disadvantages when using the well-known "loss of resistance" technique for catheter insertion. In use, the penetration of the dural membrane by the tip of the needle will result in a loss of resistance. However, this loss of resistance can occur without the entire needle tip entering the dural space. Merely the first leading edge 24 of the needle tip penetrating is enough to cause the loss of resistance, providing a false indication to the anaesthetist that the needle tip is in the required region. If the opening of the needle tip is traversed by the boundary between firm and soft tissue, subsequent insertion of the catheter is liable to be at least partially blocked by firmer tissue partially covering the opening.

Further disadvantages arise when the needle is used in conjunction with recently proposed ultrasound guiding techniques. The shape of the needle tip of the conventional tuohy needle creates two bright spots in the ultrasound image, corresponding to the leading edge 24 and the trailing edge 25 of the opening. This presents difficulties to the user when they are attempting to determine the location of the tip of the needle.

It would therefore be desirable to provide a needle that obviates or at least mitigates some of the drawbacks associated with the prior art needles.

It is one aim of the invention to provide a needle with increased ease of use.

It is a further aim of at least one aspect of the invention to provide a needle with improved echogenic characteristics.

Further aims and objects of the invention will become apparent from a reading of the following descriptions. According to the first aspect of the invention there is provided a needle for use with an ultrasound imaging system, the needle comprising a substantially cylindrical shaft having a proximal end and a distal end, and defining a longitudinal axis of the needle, wherein the distal end is cut substantially perpendicularly to the longitudinal axis.

As an example only, the needle shaft might have a diameter of up to 16 gauge, and/or might from approximately 8cm to 11cm in length.

Preferably, a portion of the shaft is echogenically enhanced.

More preferably, at least one part of an external surface of the shaft is textured.

Preferably, a portion of the distal end of the needle is echogenically enhanced.

Optionally, textured portions of the needle are coated with a solid film lubricant. Preferably, the solid film lubricant is PTFE.

Preferably, the shaft defines a circumferential external wall of the needle, the circumferential external wall being parallel to the axial direction of the needle.

Preferably, the shaft defines an internal wall of the needle, the internal wall having a first substantially cylindrical portion of a first internal diameter, and a second portion, adjacent the distal end of the shaft, wherein the second portion has an internal protrusion for deflecting the path of a catheter inserted through the needle.

The internal protrusion may be a ramp, such that moving in a direction from the proximal end to the distal end, the internal diameter of the second portion decreases.

Preferably, the internal diameter defined by the needle shaft decreases gradually.

More preferably, the protrusion only is present at only part of the circumference of the shaft. That is, the protrusion is such that the internal diameter of the second portion is rotationally asymmetric.

Preferably, the protrusion is located adjacent a lower edge of the needle shaft, such that the path of a catheter is deflected away from the lower edge.

Optionally, the external surface of the distal end of shaft is rounded. Alternatively, the external surface of the distal end of shaft is bevelled.

A portion of the needle shaft adjacent the distal end may be provided with a surface for reflecting ultrasound waves towards the proximal end of the needle.

A portion of the needle shaft adjacent the distal end may be provided with a surface inclined to the longitudinal axis of the needle shaft and partially facing the proximal end of the needle. The portion of the needle shaft provided with a surface for reflecting ultrasound waves may have an outer diameter greater than that of the main needle shaft.

The surface may extend outwardly from the main needle shaft.

Preferably, the shaft is mounted to a support member at its proximal end.

Preferably, the support member is provided with wings extending in a plane perpendicular to the axial direction of the needle.

More preferably, the wings are removably attached to the support member.

Preferably, the wings are provided with means for releasably engaging with the support member.

Preferably, the wings are defined by a substantially planar member elongate in a direction perpendicular to the axis of the needle.

Optionally, the support member is provided with wings extending perpendicularly to the axial direction of the needle, the wings releasably attached to the support member at an attachment portion, the wings being shaped such that they define a forward facing surface, at least part of which is displaced rearwardly from the attachment portion. The wings may be curved such that they form part of a surface of a cylinder oriented in a direction perpendicular to the axial direction of the needle.

Preferably, the wings are adapted to be releasably mounted in a first position on the support member such that the wings are elongate in a first direction perpendicular to the axis of the needle, and in a second position such that the wings are elongate in a second direction perpendicular to said first direction.

Preferably, an edge of the shaft opposing the lower edge is provided with a visible marker.

Alternatively, an edge of the support member opposing the lower edge is provided with a visible marker.

The external surface of the shaft may be provided with one or more visible markers extending along the length of the shaft.

According to a second aspect of the invention there is provided a needle comprising a substantially cylindrical shaft, the shaft having an internal protrusion for deflecting the path of a catheter inserted through the needle.

According to a third aspect of the invention there is provided a needle comprising a substantially cylindrical shaft having a proximal end and a distal end, and defining a longitudinal axis of the needle, and wings extending in a plane perpendicular to the axial direction of the needle, wherein the wings are adapted to be releasably mounted in a first position such that the wings are elongate in a first direction perpendicular to the axis of the needle, and in a second position such that the wings are elongate in a second direction perpendicular to said first direction.

According to a fourth aspect of the invention, there is provided a needle assembly, comprising a needle having a needle shaft and a blinder received in the needle shaft, wherein a distal end of the blinder protrudes beyond a distal end of the needle shaft.

The needle assembly configuration is such that, in operation and upon insertion, the blinder distal end will provide a first point of contact, followed by the needle shaft distal end.

Preferably, the distal end of the blinder has a shaped surface defining a pointed tip.

Preferably, the shaped surface is sub-conical.

More preferably, the shaped surface is neiloid shaped.

Preferably, the distal end of the needle shaft comprises a blunt end surface that is circumferentially located around the shaped surface of the distal end of the blinder.

Preferably, the shaped surface of the distal end of the blinder is juxtaposed against the blunt end surface of the needle shaft. Preferably, juxtaposition of the shaped surface of the blinder and the blunt end surface of the needle shaft defines a smooth distal end surface of the needle assembly.

Preferably, the needle assembly is provided with a locking mechanism for engaging the needle shaft with the blinder and preventing displacement of the blinder during insertion of the needle.

Optionally, the locking mechanism is a releasable clip- fastening mechanism.

Preferably, a portion of the blinder has a member that engages with the locking mechanism.

Preferably, a portion of the blinder is adapted to accommodate a ramp protruding from the internal surface of the needle shaft towards the distal end.

Preferably, the blinder has a locating mechanism allowing rotational alignment of the blinder within the needle shaft.

Preferably, the needle shaft is provided with a hub containing a groove and the blinder is provided with a protruding member.

Preferably, the locating mechanism comprises engagement of the hub groove with the protruding member of the blinder. Preferably, the needle is a needle in accordance with the first, second or third aspects of the invention.

There will now be described by way of example only, various embodiments of the invention with reference to the following drawings, of which:

Figure IA is a perspective view of a conventional tuohy needle in its assembled state;

Figure IB is a perspective view of the conventional tuohy needle in its dissembled state;

Figure 2 is an enlarged longitudinal-sectional view of the distal end of the tuohy needle shown in Figures IA and IB;

Figure 3A is a perspective view of a needle in accordance with a first embodiment of the invention;

Figure 3B is a longitudinal -sectional view of the needle of Figure 3A;

Figure 4A is an enlarged view of the needle tip of Figure 3 in longitudinal section;

Figure 4B is an enlarged view of the needle tip of Figure 3 having an alternative construction;

Figure 5 is a longitudinal sectional view of the needle tip of Figure 4 having a catheter inserted therethrough; Figure 6 is an enlarged longitudinal-sectional view of the tip of a needle in accordance with an alternative embodiment of the invention;

Figure 7 is an enlarged perspective view of the tip of the needle of Figure 6;

Figure 8 is a plan view of a needle in accordance with a further embodiment of the invention;

Figures 9A to 9C are enlarged longitudinal-sectional views of the tip of needle in accordance with alternative embodiments of the invention;

Figure 1OA is a longitudinal-sectional view of a needle and blinder in accordance with an embodiment of the invention;

Figure 1OB is a plan view of the needle and blinder in accordance with the embodiment of the Figure 1OA.

Referring firstly to Figures 3A, 3B and 4A, there is shown a needle 110 in accordance with an embodiment of the invention. The needle includes a needle shaft 112 defining a bore through which a catheter can be inserted. In addition, anaesthetic can be injected directly through the needle 110.

The needle 110 includes a plastic support member 114 at the proximal end of the needle. As with the needle shown in Figures IA and IB, the support member is provided with a plastic hub 118 and a blinder 119. The blinder 119 comprises a solid core extending axially from the proximal to distal end of the needle 110, and is formed with an across-axis diameter that is less than the diameter of the needle shaft 112. The diameter is sufficient to allow the blinder 119 to be located in the annular space defined by the needle shaft 112. The proximal end of the blinder 119 abuts the plastic hub 118 towards the proximal end of the needle 110. Furthermore, the plastic support member 114 has a pair of plates 120 defining a groove 121 for receiving a planar member 116. The planar member 116 is elongate in one direction, and defines a pair of wings 117 extending from the main axis of the needle. The planar member is releasably engageable with the support member, by means of corresponding snap connectors (not shown)

The distal end 113 of the needle shaft has an aperture defining an outlet for a catheter or an injected liquid. The aperture could also define an inlet for samples drawn into the needle. In contrast to the prior tuohy needle design, the tip of the needle in the present embodiment is cut perpendicularly to the longitudinal axis of the needle shaft. The exposed circular edge of the needle shaft therefore lies on a plane perpendicular to the longitudinal axis of the needle shaft. The length of the needle is thus equal around the whole circumference of the edge needle shaft.

An image of the needle tip under an ultrasound imaging system has a "bright" spot corresponding to the edge 126 of the shaft. This is in contrast to the prior art tuohy needle, an image of which has two spatially separated bright spots corresponding to the spatial separation between the leading and trailing edges of the needle aperture. The display of a single bright spot correspond to the end 126 of the needle allows the user to judge the needle position with greater precision.

The external surface of the needle shaft is provided with a roughened portion 127 for further enhancing the echogenic characteristics of the needle. The roughened portion 127 effects an improved diffuse reflection of ultrasonic beams, and thus results in a generally brightened area in the image, corresponding to the distal end 113 of the needle. This roughened portion could be obtained by a suitable sandblasting or beadblasting process.

During administration of anaesthesia, it is preferred to insert a catheter cranially into the epidural space. The needle is therefore provided with an internal protrusion adjacent the lower edge of the needle shaft. As most clearly shown in Figures 4A and 5, the protrusion is in the form of a gradual inclination of the lower internal surface of a portion of the needle shaft at the distal end, to form an internal ramp 128. The ramp functions to deflect the path of a catheter 129 inserted into the patient via the needle such that the catheter points in an upward direction as it comes out of the needle. For a correctly orientated needle, this results in a cranial progression of the catheter in the epidural space.

In the preferred embodiment, the internal ramp is formed as part of the shaft itself during a moulding, milling, or grinding process. { In an alternative construction, shown in Figure 4B, the internal ramp 128' is formed as a separate piece, and clipped into the shaft 112' by means of protrusions 138 and recesses 139. The protrusions 138 are angled towards the distal end of the shaft such that insertion of the catheter tends to retain the internal ramp 128' in a connected position.

Figure 3B shows an example needle of the present invention in its dissembled state, having plastic planar member 117 removed. The dotted lines 130 show the position at which the planar member 116 releasably engages with the support member 114 of the needle. The support member is provided with two axially separated plates 120, defining a groove 121 into which the planar member 116 is received. The planar member 116 has a portion removed to receive a central part 131 of the support member. The two pieces are provided with corresponding resilient snap connectors (not shown) to retain them in a temporarily fixed relationship.

As shown in Figures 3A and 3B, the planar member is elongate in one direction and releasably engages with the support member to form a pair of wings 117 extending laterally from either side of the needle (horizontally in the normal orientation of the needle) . The wings allow the user to firmly grip and brace the needle during insertion. In this position, the most practical way for the user to hold the needle is with the hand in the fully supinated or fully pronated position.

The needle is adapted such that the planar member can be engaged in a second position on the needle, such that the elongate direction of the planar member is perpendicular to both the longitudinal axis of the needle and the lateral direction. The wings therefore extend vertically in the normal orientation of the needle. In this position, the user may hold the needle with the hand in the mid-pronation hand position, which is the hand position that is most comfortable and offers the most control over the needle.

In order to facilitate the engagement of the wings into two positions, the central part 131 of the attachment portion of the support member between the two plates 120 is appropriately shaped. In this example, the cross- sectional profile of the central portion 131 is square, as is the corresponding cut out portion of the planar member 116. This allows the planar member to be orientated at intervals of 90 degrees.

The ability to orientate the wings means that the anaesthetist can choose his or her preferred orientation. The clinician can thus use the needle with the hand using a one-hand technique (facilitated by vertical positioning of the wings) or using a two handed technique (facilitated by horizontal positioning of the wings) .

The needle is provided with external markings 132 on the top surface of the needle shaft to provide a visible indication to the user of which edge is the upper edge of the needle, and thus the positioning of the internal ramp and the resulting deflection direction of an inserted catheter. In the example shown, the markings are in the form of a dotted line extending along the length of the needle shaft. In an alternative embodiment, such markings could provide the user with an indication of the depth at which the needle has penetrated below the surface of the skin in a similar manner to conventional "Lee's bands" .

In an alternative configuration, the visible markings are located on the support member rather than the needle shaft.

Figures 6 and 7 illustrate an alternative embodiment of the invention. The needle 210 is provided with a support member and wings, analogously to the embodiment of Figures 3 to 5. As with the previous example, the needle is provided with an internal protrusion in the form of an internal ramp 228. In this example, the tip of the needle is rounded around the circumference of the needle shaft. In longitudinal-section, the profile of the outer surface defined by the needle shaft is curved as the distal end is approached. This curvature 229 enhances the echogenic characteristics of the needle by reflecting a greater proportion of ultrasonic beams back towards the detection equipment. An area of increased brightness therefore occurs in the image formed.

The needle may be provided with one or more roughened portions, for example by sandblasting or beadblasting, in order to further enhance the echogenic characteristics, as described above.

Figure 8 illustrates a further alternative embodiment of the invention, wherein the shape of the wings is adapted. The needle 310 includes a plastic moulding 316 defining wings 317 protruding from the moulded support member. In this example, the wings 317 are releasably attached and shaped such that they curve rearwardly from the attachment portion 331. In a plan view, the wings define a forward facing surface 335, a part of which is rearwardly displaced from the point of attachment 331 with the support member. This surface is used by a clinician for bracing or gripping the needle; the clinician will typically place the fingers in the curved portion between the patient's back and the forward facing surface.

The rearwardly displacement of the surface functions to provide a more space between the forward facing surface and the needle shaft itself, thereby increasing the usable length of the needle.

Analogously to the embodiment described with reference to Figures 3A and 3B, the wings 317 may be attachable to the support member 314 in two positions, such that the wings are vertically or horizontally orientated according to the preference of the user. The wing arrangement could be used with any combination of features of the needle shaft and tip design described herein.

Figures 9A to 9C are longitudinal sections of further embodiments of the invention, offering alternative echogenic enhancing features. When used with particular transducer configurations, the ultrasonic waves may be travelling parallel to the needle shaft. This minimises the reflected signal from the needle to the receiver array, reducing the echogenic visibility of the needle. For such configurations, it is desirable to provide the needle with a reflecting surface at least partially inclined to the longitudinal axis of the needle shaft in a backward (proximal) facing direction.

Figure 9A shows a needle shaft having an annular ring 512 of increased outer diameter at its distal end. The ring has a proximal facing wall 514, defining the step from the main shaft and the annular ring. The wall 514 tends to reflect ultrasound waves travelling parallel to the needle shaft back towards the source. For a combined transmitter-receiver array positioned around the proximal end of the needle, this enhances the echogenic characteristics of the needle.

Figure 9B shows a needle shaft having a flared distal end portion 522. The outer diameter of a portion of the needle adjacent the distal end increases gradually, rather than stepwise as in the embodiment of Figure 9A. The flared portion defines a surface 524 partially directed back towards the proximal end of the needle for detection by a transducer array.

Figure 9C shows a further needle shaft, similar to that shown in Figure 9B, but having rounded edges, similar to the embodiment of Figures 6 and 7. The distal end thus has curved surfaces 524' and 229' reflecting ultrasound waves over a range of reflection angles.

Other configurations having similar reflecting surface portions at the distal end of the needle are envisaged within the scope of the invention.

In order to further enhance the echogenic characteristics of the needles of Figures 9A to 9C, the region 540 may be sandblasted or beadblasted in order to texture the surface and cause diffuse reflection of incident ultrasound waves.

With reference to Figures 1OA and 1OB there is depicted a further embodiment of the present invention, comprising a needle arrangement with a blinder at 600. This arrangement facilitates effective and accurate use of the needle. The blinder 602 is formed from a hard material, such as metal or plastic, and is located within the needle shaft 603 such that the external surface of the blinder 604 abuts the interior surface of the needle shaft 606 and interior surface of the ramp 612. The blinder 604 thus resides in the shaft in a close-fitting fashion. In order to achieve a flush fit of the blinder within the needle, the blinder 602 is shaped towards the distal end to have a tapered blinder portion, which corresponds to the ramp that is located towards the distal end of needle 600 protruding out from the internal surface of the needle shaft 603. The blinder 602 is designed to be contained within the needle during insertion of the needle.

At the distal end of the needle, the blinder 602 is designed to protrude beyond the end of the needle shaft such that the blinder provides the most distal point of the needle arrangement 600. The most distal portion of the blinder 608 has a sub-conical shape that defines a tip 609. The sub-conical distal portion 608 is characterised by an inverse parabolic taper with a decreasing tangential maximum gradient moving in a direction towards the proximal end from the tip 609 to the base region 610 of the distal portion 608. The geometry of the sub-conical portion 608 may be considered "tree shaped" or neiloid shaped. The sub-conical shaped distal part of the blinder 608 provides an advantage in that the needle and blinder described in this embodiment leads to a puncturing of tissue instead of a tear. In the situation of mistaken penetration of particularly sensitive tissue, such as the dural membrane of a patient, the pain implications for the patient are likely to be less severe.

In situ within the needle shaft 603, the base region 610 of the sub-conical blinder portion 608 abuts a blunt rounded distal top and bottom edge of the needle shaft 611a and 611b such that there is a smooth transition in surface curvature moving from the tip of the blinder 609 to the distal top edge of the needle shaft 611a and to the lower edge 611b (via the ramp 613) . The diameter of the shaft at the edge 611a, 611b and 611c is greater than the diameter of the blinder 602 and the blinder sub- conical portion 608. The narrow tip 609 is designed to assist clean entry of the needle upon penetration of the skin and the wider diameter proximal portion of the needle shaft 603 provides for the anaesthetist applying pressure to the needle to feel a defined loss of resistance as the needle penetrates the tissue.

Furthermore, the exterior surface of the needle shaft 607 is sand grinded, which provides for echogenic enhancement of the needle tip.

The blinder 602 is removably located in the needle shaft 603, allowing for later insertion of a catheter or injection of fluid. At the proximal end of the needle arrangement, the blinder 602 is provided with a locking mechanism 614 that engages with the plastic hub 616. The locking mechanism prevents the blinder from becoming displaced upon use and insertion of the needle. The locking mechanism may be a clip and button release mechanism or a screw-on hub cover. It should be appreciated that a number of alternative locking mechanisms could be used.

It should be understood that the needle and blinder of this embodiment may be adapted and applied to any of the above-described embodiments.

It will be apparent to one skilled in the art that a number of modifications could be made to the above- described embodiments within the scope of the invention. For example, the described support member and wing arrangements could be used in conjunction with any of the features of the needle shaft and needle tips described.

The textured surfaces described may be over the entire length of the needle shafts. Alternatively, the needle shaft can be banded or patterned in a variety of ways to allow the position of the needle tip to be visualised. The shaft could have textured "Lee's bands" of lcm in length and separated by lcm untextured areas. Alternatively, successive textured bands might decrease in length along the needle shaft.

It will be apparent that the cross-sectional profile of the central part 131 of the mounting portion of the needle of Figures 3A and 3B could have various polygonic shapes, thereby allowing a number of wing orientations. A series of textured portions could be provided on the needle shaft, to allow depth monitoring by the user from both an external point of view (with the naked eye) and an internal perspective (with the aid of an ultrasound viewing system) .

With reference to the described embodiments having textured portions, it may be desirable to coat the textured surface with a material that has low visibility under ultrasound monitoring. An example of a material is a solid film lubricant, such as PTFE. This will safeguard against microscopic particles of the needle shaft from the textured portions being dislodged and left in the body. The benefits of the textured portions having increased visibility under ultrasound will be unaffected.

The present invention, in its various aspects, provides an improved needle suitable for use in the administration of local and regional anaesthetic. The needle has enhanced echogenic characteristics providing an image to the user that is more easily interpreted. This facilitates use by an anaesthetist who may be relatively inexperienced in ultrasound imaging techniques. In addition, the versatile mounting arrangement of the wings increases user comfort and control.

The present invention is also applicable to a number of regional anaesthesia needles, such as the fine gauge needles used in spinal procedures.

Claims

1. A needle for use with an ultrasound imaging system, the needle comprising a substantially cylindrical shaft having a proximal end and a distal end, and defining a longitudinal axis of the needle, wherein the distal end is cut substantially perpendicularly to the longitudinal axis.

2. A needle as claimed in Claim 1 where a portion of the shaft is echogenically enhanced.

3. A needle as claimed in Claim 2 where the distal end of the needle is echogenically enhanced.

4. A needle as claimed in Claim 2 or Claim 3 where at least one portion of an external surface of the shaft is textured.

5. A needle as claimed in Claim 4 where the textured portions of the needle are coated with a solid film lubricant.

6. A needle as claimed in Claim 5 where the solid film lubricant is polytetrafluoroethylene (PTFE) .

7. A needle as claimed in any preceding Claim where the shaft defines a circumferential external wall of the needle, the circumferential external wall being parallel to the axial direction of the needle.

8. A needle as claimed in any preceding Claim where the shaft defines an internal wall of the needle, the internal wall having a first substantially cylindrical portion of a first internal diameter, and a second portion, adjacent the distal end of the shaft, wherein the second portion has an internal protrusion for deflecting the path of a catheter inserted through the needle.

9. A needle as claimed in Claim 8 where the internal protrusion is a ramp, so formed such that when moving in a direction from the proximal end to the distal end of the substantially cylindrical shaft, the internal diameter of the second portion decreases.

10. A needle as claimed in Claims 8 to 9 where the internal diameter defined by the needle shaft gradually decreases.

11. A needle as claimed in Claims 8 to 10 where the protrusion is present at only part of the circumference of the shaft.

12. A needle as claimed in Claim 11 where the protrusion is provided such that the internal diameter of the second portion is rotationally asymmetric.

13. A needle as claimed in Claims 8 to 12 where the protrusion is located adjacent a lower edge of the needle shaft, such that the path of a catheter inserted into the needle is deflected away from the lower edge.

14. A needle as claimed in any preceding Claim where the external surface of the distal end of shaft is rounded.

15. A needle as claimed in Claims 1 to 13 where the external surface of the distal end of shaft is bevelled.

16. A needle as claimed in any preceding Claim where a portion of the needle shaft adjacent the distal end is provided with a surface for reflecting ultrasound waves towards the proximal end of the needle.

17. A needle as claimed in Claim 16 where a portion of the needle shaft adjacent the distal end is provided with a surface inclined to the longitudinal axis of the needle shaft and partially facing the proximal end of the needle.

18. A needle as claimed in Claims 16 to 17 where the portion of the needle shaft provided with a surface for reflecting ultrasound waves has an outer diameter greater than that of the remainder of the needle shaft.

19. A needle as claimed in Claims 16 to 18 where the surface extends outwardly from the needle shaft.

20. A needle as claimed in any preceding Claim where the shaft is mounted to a support member at its proximal end.

21. A needle as claimed in Claim 20 where the support member is provided with wings extending in a plane substantially perpendicular to the axial direction of the needle.

22. A needle as claimed in Claim 21 where the wings are removably attached to the support member.

23. A needle as claimed in Claims 21 to 22 where the wings are provided with means for releasably engaging with the support member.

24. A needle as claimed in Claims 20 to 23 where the wings are defined by a substantially planar member elongate in a direction substantially perpendicular to the axis of the needle.

25. A needle as claimed in Claims 20 to 24 where the support member is provided with wings extending substantially perpendicularly to the axial direction of the needle, which are releasably attached to the support member at an attachment portion, where the wings are shaped such that they define a forward facing surface, at least part of which is displaced rearwardly from the attachment portion.

26. A needle as claimed in Claims 21 to 25 where the wings are curved such that they form part of a surface of a cylinder oriented in a direction substantially perpendicular to the axial direction of the needle.

27. A needle as claimed in Claims 21 to 26 where the wings are adapted to be releasably mounted in a first attachment position on the support member such that the wings are elongate in a first direction substantially perpendicular to the axis of the needle, and also in a second attachment position such that the wings are elongate in a second direction substantially perpendicular to said first direction.

28. A needle as claimed in any preceding Claim where an edge of the shaft, said edge opposing the lower edge of the shaft in use, is provided with a visible marker.

29. A needle as claimed in any preceding Claim where an edge of the support member, said edge opposing the lower edge of the shaft in use, is provided with a visible marker.

30. A needle as claimed in Claim 29 where the external surface of the shaft is provided with one or more visible markers extending along the length of the shaft.

31. A needle comprising a substantially cylindrical shaft, the shaft having an internal protrusion for deflecting the path of a catheter inserted through the needle.

32. A needle comprising a substantially cylindrical shaft having a proximal end and a distal end, and defining a longitudinal axis of the needle, and wings extending in a plane substantially perpendicular to the axial direction of the needle, wherein the wings are adapted to be releasably mounted in a first position such that the wings are elongate in a first direction substantially perpendicular to the axis of the needle, and in a second position such that the wings are elongate in a second direction substantially perpendicular to said first direction.

33. A needle assembly, comprising a needle having a needle shaft and a blinder received in the needle shaft, wherein a distal end of the blinder protrudes beyond a distal end of the needle shaft.

34. A needle assembly as claimed in Claim 33 having a configuration such that, in operation and upon insertion, the distal end of the blinder will provide a first point of contact, followed by the distal end of the needle shaft.

35. A needle assembly as claimed in Claims 33 to 34 where the distal end of the blinder has a shaped surface defining a pointed tip.

36. A needle assembly as claimed in Claim 35 where the shaped surface is sub-conical.

37. A needle assembly as claimed in Claim 36 where the shaped surface is neiloid shaped.

38. A needle assembly as claimed in Claims 35 to 37 where the distal end of the needle shaft comprises a blunt end surface that is circumferentially located around the shaped surface of the distal end of the blinder.

39. A needle assembly as claimed in Claim 38 where the shaped surface of the distal end of the blinder is juxtaposed against the blunt end surface of the needle shaft.

40. A needle assembly as claimed in Claim 39 where juxtaposition of the shaped surface of the blinder and the blunt end surface of the needle shaft defines a smooth distal end surface of the needle assembly.

41. A needle assembly as claimed in Claims 33 to 40 provided with a locking mechanism for engaging the needle shaft with the blinder and preventing displacement of the blinder during insertion of the needle.

42. A needle assembly as claimed in Claim 41 where the locking mechanism is a releasable clip-fastening mechanism.

43. A needle assembly as claimed in Claim 41 to 42 where a portion of the blinder has a member that engages with the locking mechanism.

44. A needle assembly as claimed in Claims 33 to 43 where a portion of the blinder is adapted to accommodate a ramp protruding from the internal surface of the needle shaft towards the distal end.

45. A needle assembly as claimed in Claims 33 to 44 where the blinder has a locating mechanism allowing rotational alignment of the blinder within the needle shaft.

46. A needle assembly as claimed in Claims 33 to 45 where the needle shaft is provided with a hub containing a groove and the blinder is provided with a protruding member.

47. A needle assembly as claimed in Claims 45 to 46 to where the locating mechanism comprises engagement of the hub groove with the protruding member of the blinder.

48. A needle assembly comprising a needle as claimed in Claims 1 to 32.