Abstract:
A peripheral nerve block needle for facilitating a peripheral nerve block procedure. A needle has several fenestrations along its length to allow an efflux of local anesthetic into a particular fascial compartment to treat a corresponding peripheral nerve despite only roughly approximating the location of such fascial compartment. A needle hub may be attached to the needle so that a backflow of fluid may be observed. A stylet is slidably disposed within the needle and needle hub such that selectively withdrawing the stylet from the apparatus enables a backflow of fluid into the needle hub, from which proper localization of the apparatus may be verified prior to administering local anesthetic. In this manner, local anesthetic may be effectively and efficiently administered to a peripheral nerve with reduced risk of injury to a patient.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates to innovative needles for facilitating the performance of peripheral nerve blocks and, more particularly, to a novel, atraumatic needle apparatus and method for reducing risks of injury and time associated with administering local anesthetic to a peripheral nerve. 
     2. Background 
     A peripheral nerve block is a well-established medical procedure that involves injecting a dose of local anesthetic near and around the nerve or nerve plexus that serves a surgical area. A peripheral nerve block is often used as part of a multimodal analgesia technique where the block is combined with additional medications and methods of medication delivery to target pain at several levels. Peripheral nerve blocks specifically target nociceptive impulses transmitted along peripheral nerves. Other analgesics, for example, nonsteroidal anti-inflammatory drugs (“NSAIDs”) and opioids, may be used to control pain at the injury site and/or to modify the perception of pain at the cortical level. 
     Peripheral nerve blocks are highly advantageous for continuous pain relief for several reasons. First, narcotic related side effects are less frequently reported in patients receiving continuous peripheral nerve blocks than in patients receiving epidural or intravenous analgesia. Second, urinary catheters are less frequently required in patients receiving peripheral nerve blocks compared to patients receiving epidural analgesia. Third, patient satisfaction is higher in patients having peripheral nerve blocks than in patients utilizing other analgesic methods. Fourth, the ability of a peripheral nerve block to provide site-specific relief contributes to the overall mobilization of the patient after surgery. Indeed, there is strong clinical evidence that peripheral nerve blocks, especially those administered to the lower extremity, provide superior analgesia compared to other types of analgesia and often result in earlier discharge from the hospital after major joint surgery. 
     In light of these and other advantages, it is somewhat surprising that only 20-30% of practicing anesthesiologists utilize peripheral nerve blocks as a standard method of analgesia. The most common reasons for avoiding such techniques are time constraints, fear of inadequately anesthetizing an affected nerve, and fear of injuring the affected nerve. Indeed, prior art techniques require a peripheral nerve block needle to be touching or in very close proximity to the affected nerve, without penetrating the nerve or a proximate artery or vein. Positioning the needle in this exact location can be both technically challenging and time consuming. 
     The major nerves of the lower extremity, including the sciatic and femoral nerves, are unique in that they are contained within well defined fascial compartments. Such lower extremity nerves may be successfully blocked by simply injecting anesthetic into the fascial compartment containing the nerve. Correctly identifying this fascial compartment, however, can be quite challenging. 
     Accordingly, what is needed is an improved needle for accurately administering anesthetic within a fascial compartment containing an affected lower extremity nerve. Further what is needed is an improved needle for efficiently administering anesthetic within a fascial compartment containing an affected lower extremity nerve. Finally what is needed is a method for properly locating and anesthetizing a fascial compartment containing an affected lower extremity nerve while avoiding intravascular injection and/or inadvertent penetration of the affected nerve. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     This invention is a method and apparatus for facilitating peripheral nerve block procedures. A needle comprises a plurality of fenestrations that enable local anesthetic to be administered simultaneously at several points surrounding an affected nerve. A needle further comprises a needle hub attached to a proximal end of the needle in which a backflow of fluid may be observed. A stylet is slidably disposed within the needle and needle hub apparatus such that selectively withdrawing the stylet from the apparatus enables a backflow of fluid into the needle hub, from which proper localization of the apparatus may be verified prior to administering the local anesthetic. In this manner, local anesthetic may be effectively and efficiently administered to a peripheral nerve with reduced risk of injury to a patient. 
     It is an object of certain embodiments of the present invention to facilitate proper delivery of local anesthetic with respect to an affected peripheral nerve. 
     Another object of certain embodiments of the present invention is to provide a method for performing a peripheral nerve block that enables effective delivery of local anesthetic to an affected peripheral nerve within a short period of time. 
     It is yet another object of certain embodiments of the present invention to reduce the risks related to nerve injury and intravascular injection traditionally associated with administration of a peripheral nerve block. 
     It is yet another object of certain embodiments of the present invention to provide a peripheral nerve block needle apparatus having a stylet that is easily inserted and manipulated. 
     These and other objects and features of the present invention will become more readily apparent from the following description in which preferred and other embodiments of the invention have been set forth in conjunction with the accompanying drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  is a perspective of a needle apparatus in accordance with the present invention; 
         FIG. 2  is a cross-sectional view of a human thigh depicting the location of the sciatic nerve within a fascial compartment; 
         FIG. 3  is a side view of the stylet associated with the needle apparatus of the present invention; 
         FIG. 4  is a side view of the needle and needle hub of the present invention; 
         FIG. 5  is a perspective view of the stylet cap and stylet partially inserted and in alignment with the needle hub and needle of the present invention; 
         FIG. 6  is a perspective view of the needle hub with the user&#39;s finger in contact with the raised portions for verifying the orientation of fenestrations present on a needle; and 
         FIG. 7  is an enlarged perspective view of the needle hub with a magnifying window and inserted stylet. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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 that come within the meaning and range of equivalency of the claims are to be embraced within their scope. The presently preferred embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
     As used in this specification, the terms “anesthetic” and “analgesia” are used to indicate a chemical composition to induce a loss of sensation with or without loss of consciousness. The term “fenestration” refers to an opening along the surface of a needle that enables a flow of fluid between the needle and a patient. The term “fascial compartment” refers to a intermuscular compartment defined by the fascial layers of at least one muscle. 
     Referring to  FIG. 1 , certain embodiments of the present invention comprise a needle apparatus to facilitate peripheral nerve block procedures. A needle apparatus  10  comprises three main components: a hollow needle component  12 , a needle hub component  40 , and a stylet component  60 . A hollow needle component  12  may comprise a plurality of fenestrations  20  disposed longitudinally thereon to permit a flow of fluid between the needle  12  and a patient. Fenestrations  20  are preferably located proximate a distal end  16  of a needle  12 . For example, fenestrations  20  located on a needle  12  5.0 inches in length are preferably contained along a distance measured from the tip  14  to about 1.785 inches along the length of the needle  12 . 
     A hollow needle hub component  40  may be coupled to a needle  12  mechanically by heat, an adhesive, a retaining mechanism, a secure pressure fit, or by any other means known to those in the art. A stylet component  60 , comprising a stylet  70  and a stylet cap  62 , may be freely inserted, removed and rotated within the combined needle  12  and needle hub  14  structure, and may be selectively retained therein by a pressure fit, a selective release mechanism, or by any other means known to those in the art. 
     Referring now to  FIG. 2 , a fascial compartment  30  containing lower extremity nerves may comprise only a few millimeters in width. For example, a discrete fascial compartment  30  of only a few millimeters is located between the semitendinosis muscle  32  and the biceps femoris muscle  34 . This fascial compartment  30  houses the sciatic nerve  36 , one of two major lower extremity nerves. Fenestrations  20  are spaced at relatively small intervals along the needle  12  in order to maximize an even distribution of local anesthetic to any particular fascial compartment  30 , including particularly narrow compartments such as that housing the sciatic nerve  36 . Fenestrations  20  are preferably located within 0.17 inches, and most preferably within within one to two millimeters, of each other for this purpose. Additionally, fenestrations  20  may occupy alternating sides of a needle  12  to facilitate even distribution of local anesthetic to an affected peripheral nerve. 
     As fascial compartments  30  are less resistant to the flow of local anesthetic than surrounding muscle, a greater efflux of local anesthetic is observed through fenestrations  20  corresponding to fascial compartments than through fenestrations  20  located intramuscularly. Once introduced into a fascial compartment  30 , local anesthetic passively flows to a peripheral nerve contained therein. In this manner, the needle apparatus  10  of the present invention may be introduced into a dermal area roughly corresponding to a desired fascial compartment, while ensuring effective and safe administration of local anesthetic to an appropriate peripheral nerve. Indeed, since a precise location of a peripheral nerve need not be pinpointed in order to effectively anesthetize the nerve so long as a portion of the fascial compartment  30  containing the nerve is penetrated, and since local anesthetic introduced into an appropriate fascial compartment  30  passively flows to the nerve contained therein even absent locating the needle  12  immediately adjacent the nerve, it is possible to administer a peripheral nerve block without incurring substantial risk of injury to the nerve. A peripheral nerve block may also be accomplished in less time since only a rough determination of the location of the fascial compartment  30  containing the appropriate peripheral nerve is required. These features of the present invention are highly beneficial to practitioners performing lower extremity peripheral nerve block procedures and to their patients, as the time and risks associated with such procedures are greatly reduced. 
     Referring now to  FIG. 3 , a stylet component  60  comprises a stylet  70  having a proximal end  72  and a distal end  74 . The term proximal as used herein connotes proximate to the “main body” of needle apparatus  10 , or in other words, nearer the portion of needle apparatus  10  that connects to a syringe. The term “distal” connotes a position removed from the main body of needle apparatus  10  or in other words, nearer the tip  14  of the needle apparatus  10 . A stylet  70  has a diameter and a length. The length and diameter of the stylet  70  are sufficient to occlude a hollow needle  12  and its associated fenestrations  20  when the stylet  70  is inserted into the needle  12 . 
     A stylet cap  62  has a generally spherical shape with raised portions  64  and flat areas  66  distributed throughout its surface. The generally uniform shape of the stylet cap  62  allows the stylet cap  62  to be gripped with a conventional or uniform grip from almost any angle. Raised portions  64  and flat areas  66  of a stylet cap  62  allow the stylet cap  62  to be manipulated more easily, even when the user is wearing surgical gloves. A stylet cap  62  has a cap nose component  68  disposed around the stylet  70  where the stylet  70  communicates with the stylet cap  62 . A cap nose component  68  is frusco-conical in shape with the broader base of the cone being adjacent to the stylet cap  62 . The diameter of a cap nose  68  allows it to slide into and fit securely with hollow needle hub  40 , as shown in  FIGS. 6 and 7 . A stylet cap  62  and needle hub  40  create a pressure fit that allows a stylet  70  to be rotated about its axis and still be secured by a pressure fit with the needle hub  40 . A stylet cap  62  does not need to be rotated to a particular orientation to create the pressure fit. 
     The stylet component  60  of the present invention offers several advantages. First, the stylet  70  reinforces a hollow needle  12  as the needle  12  is being inserted, positioned or retracted. Second, as mentioned above, a stylet  70  occludes fenestrations  20  on the needle  12 . Occlusion of fenestrations  20  is particularly necessary in cases where the needle  12  must be repositioned during a procedure. Additionally, the stylet  70 , when withdrawn, indicates whether the needle  12  was bent during entry. 
     In addition to the advantages above, the stylet  70  of the present invention provides a stylet cap  62  that makes it easier to see and manipulate the stylet  70  than prior art stylet caps. The stylet cap  62  of the present invention reduces the likelihood that an anesthesiologist or other practitioner will mishandle or fumble with the stylet  70 , thereby reducing both the incidence of unnecessary trauma to tissue and the time required to complete a procedure. For example, during a peripheral nerve block procedure, an anesthesiologist or other practitioner may need to withdraw and reinsert the needle  12  until he or she can verify that the needle  12  is not located intravascularly. Once verified, the anesthesiologist or other practitioner may need to promptly reinsert the stylet  70  to occlude fenestrations  20 . The stylet cap  62  of the present invention facilitates the anesthesiologist&#39;s efforts to respond promptly, once the anesthesiologist has verified proper needle placement. The stylet cap  62  provides improved handling of the stylet  70  and allows the stylet  70  to be more quickly positioned. The stylet  70  does not have to be aligned in a particular position relative to needle hub  40 , as do prior art devices. 
     The stylet  70  slides inside a hollow needle  12  through a needle hub  40  until the stylet cap  62  contacts the needle hub  40 . The cap nose component  68  slides into and contacts interior walls of the needle hub  40 , thereby creating a pressure fit between the cap nose  68  and the broad opening  46  of the needle hub  40 . The spherical shape of the stylet cap  62  obstructs the broad opening  46  of the needle hub  40 . 
     Referring now to  FIG. 4 , the needle apparatus  10  of the present invention further comprises a hollow needle  12  having a length and diameter suitable for injection of anesthetic into a fascial compartment surrounding a peripheral nerve. The length of a needle is bounded by an occluded tip  14  at a distal end  16 , and an intake opening  22  at a proximal end  18 . Fenestrations  20  are longitudinally disposed along the length of the needle  12 , and are preferably isolated on a distal end  16  of the needle  12  to facilitate an effective amount of efflux into a desired fascial compartment or other area proximate an affected peripheral nerve. Fenestrations  20  may be isolated along one side of a needle  12 , may alternate between sides of a needle  12 , or may occupy more than one side of a needle  12 . A needle hub  40  is disposed around the proximal end  18  of the needle  12 , and is configured to receive a syringe. 
     A needle hub  40  is hollow, defined by a funnel  42  having two openings, a first narrow opening  48  communicating with the needle intake opening  22 , and a broad opening  46  at the hub&#39;s proximate end. A cap nose component  68  of a stylet cap  62  may be inserted into the broad opening  46  of the funnel  42  by a pressure fit. The broad opening  46  comprises a shape corresponding to the stylet cap nose  68  to allow such a pressure fit. In one embodiment, the broad opening  46  is substantially cylindrical and tubular, thereby allowing a frusco-conical shaped stylet cap nose  68  to form a pressure fit therein. A needle hub  40  may also provide an extended opening  50 . 
     A needle hub  40  further comprises a finger grip  52  disposed about the funnel  42 . A finger grip  52  may comprise a plurality of sides and a length and diameter which allows the finger grip  52  to be easily manipulated between the thumb and forefinger. The sides of the finger grip  52  can be slightly concave to facilitate handling. Additionally, a needle hub  40  may incorporate a magnifying window  44 . Such magnifying window  44  reveals the content of the needle hub  40  in magnified view. In one embodiment, the funnel  42  is magnified so that any fluid passing into or out of the funnel  42  is more easily viewed by the user. 
     In one embodiment of the present invention, a needle hub  40  also provides fenestration indicators  56  and  58 . Fenestration indicators  56  and  58  comprise raised portions of the needle hub  40  that correspond to the relative position of fenestrations  20  located along a particular side of a needle  12 . In this manner, orientation of fenestrations  20  can be observed even when fenestrations  20  are not in view. This allows a user to remain aware of the direction of the release or uptake of fluid through fenestrations  20 . In a preferred embodiment, fenestration indicators  56  and  58  are raised from the surface of the needle hub  40  to provide visual and/or tactile verification of fenestration  20  orientation, as shown in  FIG. 5 .