Abstract:
A method of using an assembly to insert a flexible spinal needle and minimize incidence of post dural puncture headache is provided. The assembly typically includes a support needle with a non-cutting piercing tip and an exteriorly mounted flexible needle. The flexible needle gauge may be reduced, while ease of use is increased by the exterior mounting. The flexible needle provides increased flexibility allowing for movement of a patient&#39;s torso after insertion. A central stylet may be included to prevent entry of matter into the support needle opening during insertion. In other embodiments, methods for allowing single stick insertion procedures to provide better placement by allowing placement to be determined and adjusted based on physical feedback obtained during the single stick insertion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a divisional of application Ser. No. 10/694,235, filed Oct. 27, 2003, pending, the contents of the entirety of which are hereby incorporated herein by this reference. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to medical needles. It is particularly directed to methods of using flexible spinal needle assemblies.  
       BACKGROUND  
       [0003]     The advantages of continuous spinal anesthesia have long been appreciated by anesthesiologists. Unlike conventional single-shot techniques, continuous spinal anesthesia (“CSA”) with an indwelling catheter allows anesthesia of unlimited duration and the ability to carefully control the level of the block by repeated small incremental doses of anesthetic. As compared to continuous epidural anesthesia, which has become widely used as a substitute for spinal, CSA generally requires far less drug to achieve the desired effect, has a definite endpoint of correct catheter placement, requires no “test dose,” and produces a much more reliable, less spotty block.  
         [0004]     Unfortunately, technical problems have severely limited the usefulness of continuous spinal techniques. Until recently, the standard technique of inserting the spinal catheter through the spinal needle, coupled with the difficulty of manufacturing truly small needles and catheters, has meant large needles and catheters were required, resulting in an unacceptably high incidence of post-dural puncture headache (“PDPH”).  
         [0005]     In the mid 1980&#39;s, various advances fueled renewed interest in spinal anesthesia in general and in CSA in particular. Improvements in manufacturing ever-smaller conventional (Quincke™) spinal needles of 25 g, 26 g, and even 30 g significantly reduced PDPH incidence. These results allowed for the use of spinal anesthesia in age groups and procedures not previously considered suitable.  
         [0006]     At the same time, advances in catheter manufacture made possible spinal catheters of 28 g and 32 g which would fit through relatively small spinal needles. Unfortunately, these catheters proved difficult to handle, difficult to make, very expensive, and more ominously, associated with several reports of neurologic damage (i.e., cauda equina syndrome). Many clinicians therefore tried and abandoned them, and they were ultimately removed from the market by the Food and Drug Administration (“FDA”).  
         [0007]     A parallel technical development has been the introduction of non-cutting spinal needles, such as the “Pencil Point” type needles, which have been shown to drastically reduce PDPH incidence. Examples of Pencil Point type needles include the Sprotte and Whitacre non-cutting spinal needles. In terms of PDPH incidence, a 22 g Sprotte seems to be roughly equivalent to a 25 g or 26 g Quincke, while a 24 g Sprotte or 25 g Whitacre essentially eliminates the risk of PDPH.  
         [0008]     The FDA&#39;s decision to recall and ban the marketing of microspinal catheters for CSA in the U.S., and its requirement that any new device for CSA be subjected to an extremely stringent pre-market approval process, has resulted in a complete freeze on the development of these products, at least in the United States. Nevertheless, the injection of local anesthetics for the establishment of surgical anesthesia is not the only use to which such devices might profitably be put. In fact, the injection of narcotics, such as FENTANYL™, for analgesia of labor would be a very desirable use of such catheters.  
         [0009]     Installing a conventional catheter generally requires various cumbersome steps involving threading long, very thin catheters through a spinal needle. Simply threading a catheter into the end of a spinal needle can be so difficult that some manufacturers include a “threading aid” as part of their kit. Once threaded, a degree of uncertainty exists for the clinician about how far to insert the catheter. Also, a risk exists that a piece of the catheter might be sheared off by the needle if the catheter were to be pulled back during the threading operation. In such case, bits of catheter could potentially be left behind in the intrathecal space. Furthermore, removing the spinal needle while holding the catheter in position can be a challenge. Additionally, attaching a hub/injection adapter to the naked end of the 28 g or 32 g catheter can be even more of a challenge. Finally, once the adapter is successfully attached, the small lumen of the catheter permits only a slow flow of either CSF or anesthetic. In short, the conventional spinal catheter threading operation requires considerable time and effort on the part of a clinician.  
         [0010]     One problem of Sprotte and Whitacre non-cutting spinal needles is that the injection orifice is on the side of the needle. Failures of spinal anesthesia have been described as when the needle was “half-in, half-out” of the intrathecal space. Another problem with Sprotte and Whitacre spinal needles is that the smooth curved tip profile provides no definitive feedback signal or “click” when the dura is punctured. Such lack of feedback contributes to uncertainty of catheter tip placement.  
         [0011]     Conventional spinal catheters are very long and thin. As such, they are relatively cumbersome to handle without accidental contamination. They also can be difficult to secure to the skin, and can be prone to kinking at the skin or to inadvertent removal by patient movement. This kinking can result in damage to the catheter. Moreover, reports have been made of neurologic damage associated with micro-catheters. Thus, CSA itself has been abandoned in the United States, although it remains popular in Europe.  
       DISCLOSURE OF THE INVENTION  
       [0012]     In contrast to a conventional spinal catheter, the instant invention provides for simple and straightforward needle insertion without either threading a catheter through a needle or installing an adapter. The installation procedure is similar to intravenous catheter or single-shot spinal procedures already familiar to clinicians. Placement of the flexible needle over the inserting needle allows a larger diameter flexible needle to be inserted. The resulting improved diameter flexible needle allows easier and faster flow of either CSF or medicating agents.  
         [0013]     Insertion of the flexible needle tip in the intrathecal space with the instant device is more secure. The Pencil Point style non-cutting tip of the support needle promotes a low incidence of PDPH. However, the assembly tip may be shaped to provide a feedback signal when the dura is punctured. Observation of CSF with the instant design further assures a clinician that the entire orifice at the flexible needle tip is in the intrathecal space.  
         [0014]     The chance of neurologic damage is lessened with the shorter flexible needle of the present invention. The shorter length is less likely to be wedged against a nerve root. More importantly, the larger bore of the improved flexible needle promotes turbulent flow and improved mixing of any injected fluid will occur with CSF. The improved short flexible needle, which is inserted to the hub, removes ambiguity about how far to insert. The flexible needle hub greatly aids fixation to the skin. Contamination during insertion is less likely. Also, kinking at the skin is essentially impossible when a flexible kink sleeve is included.  
         [0015]     The ease, simplicity, and relative safety of the improved device may expand the use of continuous spinal anesthesia/analgesia. Essentially all lumbar epidurals could be replaced with this apparatus. Similarly, most single-shot spinals may be replaced with this apparatus “just-in-case” the procedure goes longer than expected, or the level of the block needs adjustment. A number of situations outside the operating environment could benefit from this device, non-exclusively including: acute and chronic pain control with spinal narcotics, labor analgesia, diagnostic taps, and indwelling catheters for continuous peripheral nerve blocks as well as research purposes. In effect, this apparatus can be used in every medical procedure involving needle insertion at the lumbar level of the spine. Versions of the instant device are contemplated to offer improved techniques for the insertion of a wide variety of medical catheters, including arterial lines, major nerve blocks, intraperitoneal catheters, intraventricular (brain) catheters, and intravenous catheters.  
         [0016]     The present invention provides an apparatus and method for inserting a flexible spinal needle in a quick, easy, and straightforward manner. Such a flexible spinal needle assembly has an outside diameter sized so that withdrawal of the assembly from the subarachnoid space, subsequent to insertion of the assembly thereby, permits the dura mater substantially to reseal a space formerly occupied by the assembly. An assembly typically includes a support needle, a flexible needle slidably mounted on the support needle, and a central stylet slidably inserted within the support needle. The inserted tip end of a flexible needle assembly is advantageously configured to produce a feedback signal to indicate dural puncture.  
         [0017]     A support needle preferably has a piercing point on a first end and a central hub at a second end. The piercing point protrudes from a front, distal, inserted, or tip, end of a flexible spinal needle assembly. A piercing point penetrates substantially without cutting, and helps to form a puncture hole through dura mater which automatically may substantially reseal subsequent to retraction of a flexible needle. A second end of the central stylet generally has a locking hub. The locking hub may carry a first attach structure to connect with corresponding structure of a central stylet.  
         [0018]     The front end of the support needle may be configured cooperatively to form a structural interference with a distal end of a flexible needle. Such structural interference resists relative motion between the piercing point and the distal end of the flexible needle during insertion of the flexible needle into a patient. A rear end of the support needle may carry a support hub having second attach structure to removably connect to the central hub of the central stylet. The first and second attach structures may be structured to form a removable connection, such as a LUER-LOCK™ type connection. The support hub is advantageously made from a transparent material to permit observation of fluid flow therethrough.  
         [0019]     A flexible needle may be characterized as a flexible conduit having distal and proximal ends. Preferred flexible needles have sufficient transverse flexibility to accommodate patient torso bending movement, whereby substantially to reduce a patient&#39;s awareness of the presence of the device. Flexible needles typically are made from medical grade plastic materials. For example, polyester shrink tube or similar materials may be used. The distal end of a flexible needle may be reinforced, in some instances, to resist peel-back from the front end of a support stylet. Such reinforcement may be by way of tip forming or wrappings of fine gauge wire or by a safety ribbon band. The wire or band may be made from any suitable structurally reinforcing material, including stainless steel. The proximal end of a flexible needle generally carries a needle hub having a third attach structure. This third attach structure may be adapted to structurally interfere in a releasable locking arrangement with a structure carried by the support needle.  
         [0020]     The transition from the proximal flexible needle hub to the flexible needle body may be reinforced by a kink sleeve segment. The kink sleeve segment may be constructed of a firm yet flexible material, such as nylon or other polymers. The kink sleeve is intended to cushion the transition from the hub to the flexible needle body during bending that will occur after the flexible needle is inserted and the support needle removed. For example, once the flexible needle is inserted, the hub may be bent over and taped to the skin, often at an angle of around 90 degrees.  
         [0021]     Needle hubs are typically configured for fluid flow attachment to medical fluid transfer equipment. For example, needle hubs may be configured to form LUER-LOCK™ type connections with such equipment. It may be further preferred to form the needle hub for substantially unobtrusive attachment to a patient&#39;s skin by way of an intermediary adhesive element or by designing the hub to lay flush against the patient&#39;s skin with a connection parallel thereto without a need for bending the flexible needle.  
         [0022]     A flexible spinal needle assembly may be installed using a method similar to the following: providing a flexible spinal needle assembly according to this invention; using conventional spinal needle technique to prepare skin of a patient at an injection site, apply local anesthetic, pierce skin and subcutaneous fascia, and insert a piercing point tip of the flexible spinal needle assembly; removing the central stylet subsequent to receiving a feedback signal that puncture of the dura mater has occurred; checking for CSF at the support hub; if no CSF is observed, further inserting the assembly until the tip is within the intrathecal space; or if CSF is observed, unlocking the support hub and the flexible needle hub, and while holding the support needle stationary, advancing the flexible needle until the flexible needle hub contacts the skin; removing the support needle and checking for the presence of CSF at the flexible needle hub; connecting medical fluid transfer apparatus to the flexible needle hub; and finally, securing the flexible needle hub to the skin.  
         [0023]     These features, advantages, and additional alternative aspects of the present invention will be apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0024]     In the drawings, which illustrate what is currently regarded as the best mode for carrying out the invention and in which like reference numerals refer to like parts in different views or embodiments:  
         [0025]      FIG. 1  is an exploded plan assembly view of one embodiment of a flexible spinal needle assembly according to the present invention.  
         [0026]      FIG. 2  is a cross sectional view of a portion of a flexible needle hub in accordance with one embodiment of the present invention.  
         [0027]      FIG. 3  is a plan view of the assembled flexible spinal needle assembly in  FIG. 1 .  
         [0028]      FIGS. 3A  to  3 H are plan views of different aspects of interactions between a flexible needle hub and a support hub, in accordance with the present invention.  
         [0029]      FIG. 4  is a cutaway plan view of another embodiment of a flexible needle hub in accordance with the present invention.  
         [0030]      FIG. 5  is a detail view of the distal end portion of the flexible spinal needle assembly tip, circled and designated by numeral  4 , in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     The present invention may be constructed as an integrated spinal needle and flexible spinal needle assembly  10  (much like an intravenous needle and catheter) in which the flexible needle  15  is on the outside. Placement of the flexible needle  15  on the outside provides a number of advantages. First, this design makes insertion significantly easier by eliminating the separate steps of catheter threading, insertion and hub/adapter attachment. A single “stick” is all that is required; once the needle is in, so is the conduit for infusion. Since the flexible needle  15  is larger for a given needle size, its flow and handling characteristics will be much improved, and it is easier and cheaper to manufacture.  
         [0032]     Embodiments of one possible flexible spinal needle assembly  10 , in accordance with the principles of the present invention, are illustrated in  FIGS. 1 &amp; 2 . The illustrated assembly  10  consists of three components: a central stylet  17 , a hollow support needle  19 , and a flexible needle  15 . The overall dimensions of the currently preferred embodiment of the assembly  10  are similar to a conventional spinal needle of between 22 g and 24 g.  
         [0033]     The innermost component of the assembly is preferably fashioned as a solid central stylet  17 . When inserted in the support needle  19  (discussed in detail further herein), the central stylet  17  prevents the entry of extraneous tissue or other material into the support needle opening  28  during insertion. The central stylet may also serve as a “stiffening” portion of the assembly providing extra support and stiffness to the entire assembly. The hub  25  of the central stylet  17  is outermost, or located at an extreme proximal end  26  of assembly  10 , because the central stylet  17  is the first to be removed. An attachment structure, such as tab  32 , may be located on the hub  25  for retaining the central stylet  17  in the support needle  25 . The tab  32  may interact with a corresponding attachment structure on the hub  35  of the support needle  19 .  
         [0034]     The next layer of the assembly is a removable hollow support needle  19  to support and allow insertion of the flexible needle  15 . This support needle  19  closely resembles a conventional spinal needle. The tip  27  of support needle  19  may have a pencil-point formation to allow penetration of tissue substantially without cutting. As discussed previously herein, this aids in forming a puncture hole through the dura mater which automatically may substantially reseal subsequent to retraction. An opening  28  is located near the tip  27  to allow CSF or other fluids to flow through the support needle  19  from the opening  28  to the hub  35 . It will be appreciated that where desired, suitable treatment solutions may be injected through the support needle  19 , to enter a patient&#39;s tissue through the opening  28 .  
         [0035]     The hub  35  of the support needle  19  may beneficially be made of clear plastic to allow visualization of CSF return when the central stylet  17  has been removed. Of course, any present CSF will visibly flow from the distal end  33  of support needle  19  subsequent to removal of the central stylet  17 . Optional use of clear plastic or a transparent fluid observation window in the support hub  35  can provide an additional convenience, and minimize loss of CSF.  
         [0036]     The central stylet  17  may be attachable to the support needle  19 , as illustrated in  FIGS. 1 &amp; 2 . The central hub  25  typically carries an attach structure, such as tab  32 , to interface in a structural interference with an attach structure  34  carried by support hub  35 . As illustrated, tab  32  and attach structure  34  cooperatively form a slidably engageable joint. Alternative releasable retaining joint configurations, including rotatable attachments such as LUER-LOCK™ type joints, may also be used.  
         [0037]     The outermost layer of the assembly  10  is the flexible needle  15  itself. It preferably is approximately 23 g and about the length of a conventional spinal needle, although different diameters and lengths for use with different procedures is within the scope of the present invention. Conventional plastic catheter material may be used in its construction. The flexible needle material may be reinforced with a flat ribbon internal spring  45  (shown in  FIG. 5 ), an internal or external wire wrap, or other reinforcing structure. Alternative materials, and various materials in combination, also may be used to construct a flexible needle  15 . Suitable flexible needle material produces a flexible needle  15  which is fairly stiff and has a sufficiently high tensile strength to maintain structural integrity during insertion, while in the body, and during retraction from a patient. A flexible needle  15  desirably possesses sufficient transverse flexibility to deform and accommodate patient motion to reduce irritation from the presence of a foreign body.  
         [0038]     A slippery nonstick surface is generally provided to ease insertion and removal of the flexible needle  15 . The tip  29  of flexible needle  15  may be tapered into a curve to blend smoothly into the edge of support needle  19  (see,  FIG. 5 ). The degree of this curved taper may be governed by a tradeoff between the decreased resistance to insertion of an extreme taper versus the fragility and tendency to peelback of a very thin leading edge. A preferred taper provides ease of insertion, a feedback signal to indicate entry of flexible needle  15  through the dura, and sufficient tensile strength to prevent peelback. The feedback signal may be described as a distinct “click” or a change in required insertion force. The “click” may be a sonic event, or may be perceptible only through the clinician&#39;s fingers in contact with the assembly.  
         [0039]     Flexible needle tips  29  having shapes other than those illustrated in  FIGS. 1, 3  &amp;  5  are within contemplation. For example, manufacturing or material requirements may influence the shape of a tip  29 . An alternative flexible needle may include a reinforcing wire of fine gauge. Such a wire may be embedded into the material forming the sealing wall of flexible needle  15  to reinforce against peelback. The wire may also be spiraled along the length of the flexible needle to provide additional strength to resist collapse, kinking, or breakage of a flexible needle  15 . Alternatively, a flat spring ribbon  45  may be used to provide reinforcement.  
         [0040]     The flexible needle hub  39  typically includes a LUER-LOCK™ type connector, or other attachment structure, for easy and secure connection with common infusion tubing, injection ports, or syringes, and other medical fluid transfer apparatus. Since the flexible needle  15  may be inserted all the way to the hub  39 , a flat, circular flange, or other ergonomically shaped structure, may be provided on the surface of the hub which rests against the patient&#39;s skin to facilitate easy tape fixation. Fixation to the patient&#39;s skin may be accomplished with a slotted circular foam tape. Of course, other tapes or adhesive systems may also be used. A quantity of suitable adhesive or tape could be included in a prepackaged flexible spinal needle kit. A flexible needle hub  139  (see  FIG. 4 ) that lays flat against patient&#39;s skin and allows attachment of a line at an angle substantially parallel to the skin, rather than generally perpendicular thereto, may be used. Such a flexible needle hub may be more comfortable for a lengthy procedure.  
         [0041]     It is desirable to prevent inadvertent premature removal of the support needle  19  from the flexible needle  15 . In the embodiment depicted in  FIGS. 1-3 , support hub  35  receives thread structure  37  located on the flexible needle hub  39  and locks with rotation. Such a positive connection may be desirable and can form a LUER-LOCK™ or other rotatable-type joint. Other such interlocking or even alternative retaining structure may also be used. For example, a secure friction fit attachment between support needle  19  and flexible needle  15  is within contemplation in the practice of this invention, as is a structural interference fit of attachment structures similar to shown in connection with tab  32  on the central stylet  17 .  
         [0042]      FIGS. 3A  to  3 G depict several aspects of relationships between the hubs of a flexible needle  15  and a support needle  19  that may prevent premature removal of the support needle  19  or aid in support needle  19  removal at the appropriate point of a procedure.  FIG. 3A  depicts a support needle  19 A having a support hub  35 A that includes a plurality of retaining levers  40 A. Each lever  40 A is attached to the body of the support hub  35 A by a pivot structure, such as pin hinge  42 A, allowing the distal end of the retaining lever  40 A to be rotated away from hub  35 A as the proximal end  46 A is depressed. The retaining levers  40 A expand around the flexible needle hub  39 A allowing the flexible needle hub  39 A and support hub  35 A to be slid together as the needle  19 A is inserted in the flexible needle  15 A. The distal end of the retaining levers  40 A include an attach structure, such as the enlarged end  44 A, that interacts with a corresponding attach structure, such as the ridges  50 A and  52 A on the flexible needle hub  39 A, to retain the hubs in position to one another. Ridges  50 A and  52 A may be formed as discrete bumps located on the flexible needle hub  39 A or may be formed as raised ridges running around the entire circumference of the hub  39 A. To release support needle  19 A from flexible needle  15 A, retaining levers  40 A are depressed at the proximal end  46 A, which may include a grip structure, and the hubs may then be separated. It will be appreciated that although two retaining levers  40 A are depicted, any suitable number may be used and all such embodiments are within the scope of the present invention.  
         [0043]      FIG. 3B  depicts a somewhat similar arrangement where a retaining lever  40 B is rotatably attached to the support hub  35 B and includes an enlarged distal end  44 B with a lip that forms a structural interference fit with an attach structure, such as distal end  50 B of the flexible needle hub  39 B. Additionally, retaining lever  40 B includes a detach assisting structure, such as detach bar  48 B that resides between the flexible needle hub  39 B and the support hub  35 B in the retained position. When proximal end  46 B of the retaining lever  40 B is depressed, distal end  44 B rotates out from the flexible needle hub  39 A releasing it. Simultaneously, detach bar  48 B presses against the proximal end of the flexible needle hub  39 B, causing support needle  19 B to begin withdrawing from flexible needle  15 B. It will be appreciated that although only one retaining lever  40 B is shown for clarity, any desired number of retaining levers  40 B may be used. Further, although a pin hinge  42 B is depicted, any suitable rotatable connection, such as a living hinge formed from injection molded plastic, may be used.  
         [0044]      FIG. 3C  depicts another detach assisting structure for removing support needle  19 C (not shown) from flexible needle  15 C. In such an embodiment, the flexible needle hub  39 C and support hub  35 C may be releasably attached to one another by a friction fit, or by a small amount of a weak adhesive. A detach lever  50 C is attached to the flexible needle hub  39 C and includes a detach assisting structure such as detach wedge  52 C. Detach lever  50 C may be attached to the flexible needle hub  39 C in any suitable fashion, as by a pin hinge or by forming a living hinge  56 C by fashioning detach lever  50 C as an extension of the distal end of the flexible needle hub  39 C. The detach wedge  52 C may be disposed so the leading edge thereof is disposed between the distal end of the support hub  35 C and the proximal end of the flexible needle hub  39 C body. To actuate detachment, the detaching lever  50 C is depressed by pressing on the proximal end  54 C thereof causing he detachment wedge  52 C to advance further between the hub  35 C and  39 C forcing them apart and the support needle  19 C to withdraw from the flexible needle  15 C.  
         [0045]     Another example of aspects of a detach assisting structure is depicted in  FIG. 3D . A detach lever  52 D is rotatably attached to flexible needle hub  39 D through a pin hinge  54 D or another flexible connection. The attachment may occur on a protrusion or detachment extension  51 D, extending out from the flexible needle hub  39 D body. Detach lever  52 D has a detaching end  56 D that resides between the flexible needle hub  39 D and the support hub  35 D when the hubs are in the retained position. The opposite actuation end  58 D of the detach lever  52 D may include a grip area formed as a roughened surface. Detach lever  52 D is actuated by pressing the actuation end  58 D in the distal direction causing the detaching end  56 D to rotate out from the flexible needle hub  39 D pressing against the distal end of the support hub  35 D, causing support needle  19 D (not shown) to begin withdrawing from flexible needle  15 D.  
         [0046]      FIG. 3E  depicts another aspect of a connection between a flexible needle hub  39 E and a support hub  35 E. Flexible needle hub  39 E has an enlarged bore opening  50 E at its proximal end into which the distal end of support hub  35 E may be inserted upon insertion of the needle  19 E (not shown) into flexible needle  15 E. The walls of enlarged bore opening  50 E and the distal end of support hub  39 E fit together snugly forming a friction fit there between to retain the hubs together. The hubs may be constructed of material selected for a suitable coefficient of friction to maintain the relationship between the hubs.  
         [0047]      FIG. 3F  depicts a flexible needle hub  39 F including an enlarged bore opening  50 F and a support hub  35 F having a relationship similar to that described with respect to  FIG. 3E . Additional retention structures are also depicted. Support hub  35 F includes a lip  40 F extending distally from the hub body to create a recess  41 F. Lip  40 F includes an enlarged distal end  42 F and may be resilient. As the needle  19 F is inserted into flexible needle  15 F and a portion of the support hub  35 F is inserted into enlarged bore opening  50 F, lip  40 F passes over a portion of the flexible needle hub  39 F, flexing outward to allow enlarged distal end  42 F to pass over a ridge  52 F on the flexible needle hub  39 F. Enlarged distal end  42 F blockably interacts with ridge  52 F to prevent inadvertent removal of the needle  19 F. At the appropriate point in the procedure, the hubs may be separated by applying sufficient force to the hubs in opposite directions to cause the lip  40 F to flex and allow the enlarged distal end  42 F to pass over the ridge  52 F. Grip points  50 F and  44 F may be provided on the flexible needle hub  39 F and support hub  35 F, respectively, to assist in the removal of the needle  19 F. It will be appreciated that lip  40 F may be formed as an extension around the entire circumference of the support hub  35 F taking the shape thereof, whether generally circular or otherwise, or may be formed as a plurality of separate extensions, and all such embodiments are within the scope of the present invention.  
         [0048]      FIGS. 3G and 3H  depict a rotatable retaining relationship between flexible needle hub  39 G and support hub  35 G. Support hub  35 G includes a number of discrete protrusions, such as retaining tabs  40 G at a point along the hub body. Flexible needle hub  39 G includes an enlarged bore opening  50 G into which a portion of the body of the support hub  35 G may be inserted. The mouth  52 G of enlarged bore opening  50 G is best depicted in  FIG. 3H . A central section of mouth  52 G allows the support hub  35 G body to pass therethrough, yet is too small to allow the tabs  40 G to similarly pass. Mouth  52 G includes bays  53 G extending into the proximal end of the flexible needle hub  39 G from the central section of the mouth  52 G. Each bay  53 G corresponds to a tab  40 G and allows passage therethrough to the enlarged bore opening.  
         [0049]     When support hub  39 G is fully inserted into the enlarged bore opening  50 G, support needle  19 G is fully inserted in the flexible needle  15 G and tabs  40 G reside in the enlarged bore opening  50 G. Support hub  35 G may then be rotated with respect to the flexible needle hub  39 G, so that tabs  40 G no longer align with bays  53 G. Support needle  19 G is then blockably prevented from premature removal from the flexible needle  15 G. Removal can be accomplished by rotating the support hub  39 G to align tabs  40 G with bays  53 G and then slidably withdrawing the support hub  35 G. It will be appreciated that although two tabs  40 G and bays  53 G are depicted, any suitable number may be used.  
         [0050]     As best shown in  FIG. 3 , flexible needle  15  may include a flexible kink sleeve  18 . Kink sleeve  18  covers a portion of the proximal surface of the flexible needle  15  to protect the area covered against kinking and damage during bending. Desirably, the kink sleeve  18  will begin at the base of the flexible needle  15  inside the hub  39  (as depicted in  FIG. 3 ) to provide maximum protection, although alternate embodiments where kink sleeve begins distal to the base of the flexible needle inside the hub  39 , or at the base of the hub  39  are within the scope of the present invention. Kink sleeve  18  may extend distally along the length of the flexible needle  15  to a length appropriate for the planned use of the flexible needle. Typically, kink sleeve  18  will extend to a length sufficient to prevent kinking of the flexible needle at the skin of the patient or within the skin and fascia of the patient. Kink sleeve  18  may be constructed of any suitable flexible material that is medically acceptable, including polymers such as nylon.  
         [0051]     When flexible needle  15  is fully inserted, a portion of the kink sleeve  18  will reside within the skin and fascia of the patient. The hub  39  may then be bent over and taped to the skin, if desired. The kink sleeve  18  acts to protect the flexible needle  15  during this bending process, which may bend the flexible needle  15  at an angle of about 90 degrees or more. The kink sleeve  18  absorbs the force of the bend and maintains the flexible needle  15  in a position allowing flow therethrough. Kinking of the flexible needle  15  is thus minimized, and may be prevented. The kink sleeve  18  may be impregnated, coated, or otherwise treated with a biocompatible infection resistant substance to prevent adverse tissue reaction or infection at the flexible spinal needle entry site. Embodiments where the flexible needle hub  139  ( FIG. 4 ) lies flat against the skin, allowing attachment at an angle generally perpendicular to insertion may further avoid potential kinking. Similar to kink sleeve  18 , the flexible needle hub  139  may be impregnated, coated, or otherwise treated with a biocompatible infection resistant substance to prevent adverse tissue reaction or infection at the flexible spinal needle entry site.  
         [0052]      FIG. 4  depicts a flexible needle hub  139  that lies flat against the patient&#39;s skin and allows a line to be attached at an angle generally perpendicular to the direction of flexible spinal needle insertion. The hub  139  includes a body  102  with a generally planar proximal end  104 , from which the flexible needle  115  extends. A kink sleeve  118  may be included on the flexible needle  115 . A bore  114  continuous with the bore of the flexible needle  115  extends in line therewith through the body  102  to allow placement of the support needle  19  and central stylet  17  through alignment opening  120 . A connection bore  116  connects to the bore  114 , from an angle generally perpendicular thereto and passes to a connection outlet  110  generally perpendicular to the angle of insertion of flexible needle  115 . The junction between connection bore  116  and bore  114  may be formed as a T-shaped junction as depicted in  FIG. 4 .  
         [0053]     Connection outlet  110  may include a connection structure, such as the LUER-LOCK™ type threads  112  depicted in  FIG. 4 , in order to allow tubing, a connection line, a syringe or other structure to be attached thereto in communication with connection bore  116  and bore  114 . A line connected to connection outlet  110  may lay flat on the skin of a patient resulting in a more comfortable connection than a perpendicular connection.  
         [0054]     Similarly, alignment opening  120  may include a connection structure, such as LUER-LOCK™ type threads, in order to allow tubing, a connection line, a syringe or other structure to be attached thereto in communication with bore  114 . Upon withdrawal of the support needle  19  after flexible needle  15  placement, alignment opening  120  may be closed by capping, with a cap or an injectable port (to provide another point for the introduction of suitable treatment solutions to the flexible needle  15 ). In some embodiments, a resealable puncturable membrane may be provided across the alignment opening  120  (or the bore  114  above connection bore  116 ) to allow insertion of a support needle and central stylet therethrough, while sealing the bore  114  upon their removal.  
         [0055]     Flexible needles  15  may be made from suitable medical grade plastic type materials. For example, polyester shrink tubing may be employed with one embodiment of the device, although it will be appreciated that any suitable material, including other polymers, may be used. Flexible needles  15  may be composed of a single material, or may be a composite of two or more materials to provide the desired flexible needle handling characteristics. Fine gauge wire, such as stainless steel wire, or a flat internal ribbon spring  45 , may be incorporated into a flexible needle sealable wall to improve resistance to peelback. The distal ends may alternatively be reinforced with metal bands. Hubs  25 ,  35  and  39  are typically also made from medical grade plastic type materials. The central stylet  17  and support needle  19  are typically made from a medically acceptable metal, such as stainless steel or titanium.  
         [0056]     The design of this device makes the placement of a spinal flexible needle  15  quick, easy, and straightforward. It should be so easy, in fact, that most clinicians may choose to use this device for every spinal procedure they perform. The initial steps of skin preparation, local anesthetic infiltration, and needle insertion are identical to those now used with conventional spinal needles. As the assembly  10  is being inserted and the clinician feels the slight “click” upon dural puncture, he or she removes the central stylet  17 . If the insertion has been successful, CSF will promptly appear at the hub  35  of the support needle  19 . If the dura has not been penetrated, the entire assembly  10  may continue to be advanced until dural puncture is achieved. If desired, the central stylet  17  may be reinserted prior to continued advancement in order to prevent tissue from entering the opening  28 .  
         [0057]     Once CSF is observed at the hub  35  of the support needle  19 , the clinician can be certain that the tip  29  of the flexible needle  15  is within the intrathecal space. If desirable for the procedure, the clinician may continue to advance the hollow needle/flexible needle  19 / 15  assembly another centimeter or so. At this point, the hub  35  of the hollow needle  19  is typically twisted to unlock it from the flexible needle hub  39  or  139 , and while holding the hollow needle  19  stationary, the flexible needle  15  is advanced all the way until the hub  39  or  139  contacts the patient&#39;s skin. For embodiments including a kink sleeve  18 , this advancement inserts, or further inserts, the kink sleeve  18  within the patient&#39;s skin.  
         [0058]     At this point, the hollow support needle  19  may be removed, and the appearance of CSF at the flexible needle hub  39  or  139  will confirm the correct placement of the flexible needle  15 . The desired injection port, tubing, or other medical fluid transfer apparatus, may then be attached to the flexible needle hub  39  (or  139 ) such as by way of attach structure  37  (or  112 ). Where necessary, the flexible needle  15  may be bent and taped to the patient&#39;s skin before or after the attachment of the corresponding apparatus, if required. Where included, kink sleeve  18  protects the flexible needle  15  from kinking and damage at the bend. A piece of slotted, circular foam tape (which might also be treated with an antimicrobial) may also be applied to fix the hub  39  or  139  to the skin, prevent dislodging of the flexible needle  15 , and cushion the patient to reduce potential irritation from the hub  39  or  139 .  
         [0059]     The flexible needle  15  may then be left in place for as long as clinically necessary and, assuming adequate tensile strength, be easily and safely removed when appropriate. At the time of removal, since the non-cutting point  22  of the support needle  19  never lacerated any fibers in the dural membrane, the mesh-like fibers may relax to their original position, thus automatically closing the dural puncture. Therefore the PDPH incidence is expected to be in agreement with Sprotte and Whitacre needles, despite the luxury of a reasonably large flexible needle  15  in a device according to the instant invention.  
         [0060]     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.