Abstract:
The invention provides improved apparatuses and related methods for the detection of needle penetration into negative pressure corporal spaces such as the epidural space. In one aspect, the invention provides a negative pressure indicator apparatus, either integrated with a needle hub or attachable thereto, which accommodates insertion of a stylet into the needle hub and needle thereof while the negative pressure indicator apparatus remains in its operable position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application Ser. No. 61/838,786 filed Jun. 24, 2013, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to the field of epidural needles and anesthesia. 
       BACKGROUND OF THE INVENTION 
       [0003]    Epidural anesthesia is a popular method of treating acute and chronic pain. Most commonly, the “loss of resistance” (LOR) technique has been used to detect needle penetration into the space. This technique involves connecting the needle, such as a Tuohy needle, via a needle hub to a syringe filled with saline solution and continuously pushing on the piston of the syringe while the needle is inserted toward the epidural space until a loss of resistance is encountered indicating that the needle tip has entered the space. An alternative method of detection is the “hanging drop” (HD) technique which relies on visualizing the aspiration of a small volume of fluid from the hub of the needle as the pressure at the needle tip decreases below atmospheric level upon entry into the epidural space. However, conventional application of the hanging drop technique is less than optimal due to the number of manipulations required while the needle is inserted in a patient. U.S. Pat. No. 7,175,608 teaches a device and method for identification of the epidural space that involve pressurizing a diaphragm with liquid and visualizing collapse of the diaphragm upon needle entry into the epidural space. 
         [0004]    What is needed and provided by the present invention are new and improved apparatuses and methods for detecting needle penetration into a negative pressure (subatmospheric) space such as the epidural space. 
       SUMMARY OF THE INVENTION 
       [0005]    One embodiment of the invention provides a hub and needle apparatus for detecting penetration of the needle into a negative pressure space, which includes: 
         [0006]    an elongate needle having a proximal end, a distal penetration end and a longitudinal central axis, wherein a lumen extends lengthwise through the needle and opens at each end of the needle; and 
         [0007]    a needle hub having a proximal end, a distal end and a longitudinal axis, the needle hub including:
       a longitudinally aligned (extending) lumen formed by the needle hub, a proximal end portion of the needle connected to the distal end of the hub with the lumens of the needle and hub in fluid communication with each other,   a stylet port disposed at the proximal end of the hub assembly, the stylet port communicating with the lumen of the hub assembly and having a longitudinal axis which is coaligned with the longitudinal central axis of the needle at the needle&#39;s proximal end; and   a pressure change indicator in fluid communication with the longitudinally aligned (extending) lumen of the hub,
 
wherein a stylet inserted into the stylet port is able to extend unimpeded through the longitudinally aligned (extending) lumen of the hub into the lumen of the needle.
       
 
         [0011]    The proximal stylet port may include a stylet penetration-resealable plug (such as an elastomeric rubber stopper) or integral structure, such as one presenting a self-sealing split septum, disposed in/at the proximal stylet port so that a stylet may be inserted therethrough and when the stylet is withdrawn the stylet port will automatically seal-up creating an air tight seal of the stylet port. Alternatively, a removable plug, such as rubber or plastic plug or stopper, may be disposed in the proximal stylet port reversibly sealing it (when needed following removal of the stylet immediately prior to advancing the needle toward the presumptive location of a negative pressure space such as the epidural space). 
         [0012]    In one variation, the hub and needle apparatus may include two reversibly connectable component parts, wherein: 
         [0013]    (i) the first component part comprises:
       an elongate needle having a proximal end, a distal penetration end and a longitudinal central axis, wherein a lumen extends lengthwise through the needle and opens at each end of the needle; and   a needle hub having a proximal end, a distal end and a longitudinal axis, the needle hub including:   a longitudinally aligned (extending) lumen formed by the needle hub, a proximal end portion of the needle connected to the distal end of the hub with the lumens of the needle and hub in fluid communication with each other, and   a proximal end port connector in communication with the longitudinally aligned (extending) lumen formed by the needle hub; and       
 
         [0018]    (ii) the second component part includes:
           a rigid body having a proximal end, a distal end, a longitudinal central axis, a longitudinally aligned (extending) lumen formed therethrough, and comprising:   a distal end port connector opening into the longitudinally aligned (extending) lumen of the rigid body and sized and configured to connect to the proximal end port connector of the needle hub of the first component, and   a proximal end stylet port opening into the longitudinally aligned (extending) lumen of the rigid body, and   a pressure change indicator in fluid communication with the longitudinally aligned (extending) lumen of the rigid body,           
 
         [0023]    wherein the first and second components are mutually sized and configured so that when they are connected a stylet inserted into the stylet port is able to extend unimpeded through the longitudinally aligned (extending) lumens of the rigid body and needle hub into the lumen of the needle, and 
         [0024]    wherein the distal end port connector of the second component part is connected to the proximal end port connector of the first component part. 
         [0025]    Another embodiment provides only the aforementioned second component of the recited two-component part hub and needle apparatus. A related embodiment provides a negative pressure detection apparatus for use with a needle and hub assembly, which includes: 
         [0026]    a rigid body having a proximal end, a distal end a longitudinal central axis, a longitudinally aligned (extending) lumen formed therethrough, and including:
       a distal end port opening into the longitudinally aligned (extending) lumen of the rigid body;   a proximal end stylet port opening into the longitudinally aligned (extending) lumen of the rigid body; and   a pressure change indicator in fluid communication with the longitudinally aligned (extending) lumen of the rigid body,
 
wherein the rigid body is sized and configured so that a stylet inserted into the stylet port is able to extend unimpeded through the longitudinally aligned (extending) lumen and out the distal end port.
       
 
         [0030]    The invention also provides methods for detecting the penetration of a needle into a negative pressure space, such as the epidural space, and for inserting the needle therein, that employ the apparatuses described herein. 
         [0031]    Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1A  shows a perspective view of a hub and needle embodiment of the invention that includes a negative pressure indicator dome and a stylet inserted therein. 
           [0033]      FIG. 1B  shows an exploded view of the component parts of the embodiment shown in  FIG. 1A . 
           [0034]      FIG. 1C  shows a medial lengthwise cross-sectional cut-away view, across the long axis of the wings of the hub, of the embodiment shown in  FIG. 1A . 
           [0035]      FIG. 1D  shows a medial lengthwise cross-sectional cut-away view through the dome assembly of the embodiment shown in  FIG. 1  (perpendicular to the cross-sectional plane of view shown in  FIG. 1C ). 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    The invention provides a negative pressure indicator apparatuses, integrated with a needle hub or attachable thereto, which accommodate insertion of a stylet into the needle hub and needle thereof 
         [0037]    One embodiment of the invention provides a hub and needle apparatus for detecting penetration of the needle into a negative pressure space, which includes: 
         [0038]    an elongate needle having a proximal end, a distal penetration end and a longitudinal central axis, wherein a lumen extends lengthwise through the needle and opens at each end of the needle; and 
         [0039]    a needle hub having a proximal end, a distal end and a longitudinal axis, the needle hub including:
       a longitudinally aligned lumen formed by the needle hub, a proximal end portion of the needle connected to the distal end of the hub with the lumens of the needle and hub in fluid communication with each other,   a stylet port disposed at the proximal end of the hub assembly, the stylet port communicating with the lumen of the hub assembly and having a longitudinal axis which is coaligned with the longitudinal central axis of the needle at the needle&#39;s proximal end; and   a pressure change indicator in fluid communication with the longitudinally aligned lumen of the hub,
 
wherein a stylet inserted into the stylet port is able to extend unimpeded through the longitudinally aligned lumen of the hub into the lumen of the needle.
       
 
         [0043]    The pressure change indicator may include a chamber having a lumen sealed by a visibly deformable diaphragm, the lumen of the chamber in communication with the longitudinally aligned (extending) lumen of the hub. A rigid at least partially transparent cover may cover the diaphragm. The cover may be not air-tight so that the space between the diaphragm and the inner surface of the cover is open to the surrounding atmosphere. The cover may have one or more holes through it. The cover may, for example, be dome-shaped. Alternatively, the pressure change indicator may for example, be an electronic pressure indicator configured to indicate the drop in pressure experienced when the needle tip enters a negative pressure space, such as the epidural space. An electronic pressure indicator may, for example, be of any of the types provided by U.S. Pat. No. 4,919,653 which is hereby incorporated by reference. For example, an electronic pressure indicator may include a pressure sensor in communication with the interior lumen of the apparatus, the sensor operably connected to a processor (such as an integrated circuit), one or more indicators such as a light-emitting diode or audible alarm/buzzer/speaker under control of the processor and power source such as a battery, wherein the processor, sensor and one or more indicators are mutually configured (including any required logic/processor instructions, i.e., programming, in tangible processor-accessible memory) to provide a discernible indication (e.g., LED turning or changing color and/or audible indication) to the practitioner when the lumen pressure drops upon entry of the needle tip into a negative (relatively) pressure space such as the epidural space. 
         [0044]    The proximal stylet port may include a stylet penetration-resealable plug (such as an elastomeric rubber stopper) or integral structure, such as one presenting a split septum, disposed in/at the proximal stylet port so that a stylet may be inserted therethrough and when the stylet is withdrawn the stylet port will automatically seal-up creating an air tight seal of the stylet port. Alternatively, a removable plug, such as rubber or plastic plug or stopper, may be disposed in the proximal stylet port reversibly sealing it (when needed following removal of the stylet immediately prior to advancing the needle toward the presumptive location of a negative pressure space such as the epidural space). 
         [0045]    The hub and needle apparatus may further include: a stylet comprising an elongate stylet member having a proximal end and a distal insertion end and a stylet handle connected to the proximal end of the elongate stylet member, wherein the elongate stylet member is inserted through the stylet port of the hub and needle apparatus such that the elongate stylet member extends into the longitudinal lumen of the needle. If a stylet penetration-resealable plug is present, the stylet is inserted through the plug. The handle (cap) of the stylet may be sized and configured to surround and/or engage the proximal stylet port portion of the hub. The stylet may be a conventional stylet in which there are no internal fluid channels from the proximal side of the handle to the distal side of the handle. 
         [0046]    The hub and needle apparatus may, for example, be made up of one body or it may be made of two or more reversibly connectable component parts. For example, the hub and needle apparatus may include two reversibly connectable component parts, wherein: 
         [0047]    (i) the first component part comprises:
       an elongate needle having a proximal end, a distal penetration end and a longitudinal central axis, wherein a lumen extends lengthwise through the needle and opens at each end of the needle; and   a needle hub having a proximal end, a distal end and a longitudinal axis, the needle hub including:   a longitudinally aligned lumen formed by the needle hub, a proximal end portion of the needle connected to the distal end of the hub with the lumens of the needle and hub in fluid communication with each other, and   a proximal end port connector in communication with the longitudinally aligned lumen formed by the needle hub; and       
 
         [0052]    (ii) the second component part includes:
           a rigid body having a proximal end, a distal end, a longitudinal central axis, a longitudinally aligned lumen formed therethrough, and comprising:   a distal end port connector opening into the longitudinally aligned lumen of the rigid body and sized and configured to connect to the proximal end port connector of the needle hub of the first component, and   a proximal end stylet port opening into the longitudinally aligned lumen of the rigid body, and   a pressure change indicator in fluid communication with the longitudinally aligned lumen of the rigid body,           
 
         [0057]    wherein the first and second components are mutually sized and configured so that when they are connected a stylet inserted into the stylet port is able to extend unimpeded through the longitudinally aligned lumens of the rigid body and needle hub into the lumen of the needle, and 
         [0058]    wherein the distal end port connector of the second component part is connected to the proximal end port connector of the first component part. 
         [0059]    The pressure change indicator may, for example, be any of the kinds previously described. The proximal stylet port may include any of the kinds of plugs or stoppers previously described. The two part hub and needle apparatus variation may also include a stylet as previously described inserted into the proximal stylet port and extending distally into the longitudinal lumen of the needle. 
         [0060]    The invention also provides kits that include a hub and needle apparatus and a stylet sized and configured to be inserted into the proximal stylet port of the apparatus and extend distally into the lumen of the needle of the apparatus. When the proximal stylet port does not include a stylet penetration reversibly sealable plug, a removable plug/stopper sized and configured to seal the proximal stylet port may be included in the kit. The components of the kit may be provided separate or partially or fully assembled with each other in an operable configuration. 
         [0061]    Another embodiment provides only the aforementioned second component of the recited two-component part hub and needle apparatus. 
         [0062]    A related embodiment provides a negative pressure detection apparatus for use with a needle and hub assembly, which includes: 
         [0063]    a rigid body having a proximal end, a distal end a longitudinal central axis, a longitudinally aligned lumen formed therethrough, and including:
       a distal end port opening into the longitudinally aligned lumen of the rigid body;   a proximal end stylet port opening into the longitudinally aligned lumen of the rigid body; and   a pressure change indicator in fluid communication with the longitudinally aligned lumen of the rigid body,
 
wherein the rigid body is sized and configured so that a stylet inserted into the stylet port is able to extend unimpeded through the longitudinally aligned lumen and out the distal end port.
       
 
         [0067]    The pressure change indicator may, for example, be any of the kinds previously described. The proximal stylet port may include any of the kinds of plugs or stoppers or reversible seals previously described. A stylet penetration-resealable plug or integral structure, such as one presenting a split septum, may be disposed in/at the proximal stylet port so that a stylet may be inserted therethrough and when the stylet is withdrawn the stylet port will automatically seal-up creating an air tight seal of the stylet port. Alternatively, a removable plug, such as rubber or plastic plug or stopper, may be disposed in the proximal stylet port reversibly sealing it. The distal port of the negative pressure detection apparatus may be a (be configured as) fluid connector, such as a conical male or female fluid connector, such a connector having a male or female Luer connector geometry, for example a Luer slip or Luer lock geometry, for connection to a corresponding mateable distal connector of a hub and needle assembly. 
         [0068]    Still another embodiment provides a negative pressure indicator, which includes: 
         [0069]    an at least partially transparent rigid cover having an outer surface and an inner surface, wherein a hole is formed between the outer surface and the inner surface; 
         [0070]    a flexible pressure indicator diaphragm/membrane; and 
         [0071]    a rigid base forming an internal lumen, 
         [0000]    wherein the diaphragm/membrane is secured between the cover and the base so that a space is present on each side of the diaphragm/membrane and the diaphragm/membrane sealably separates the lumen formed by the base from the space between the diaphragm/membrane and the cover. Thus, the side of the diaphragm/membrane facing the cover is open to the atmosphere due to the hole in the cover. The diaphragm/membrane may have a shape biased toward the cover, such as a convex shape, such as a dome shape when there is no pressure differential across the two sides of the diaphragm membrane. The cover may also, for example, have a dome-shape. A related embodiment provides a needle and hub assembly including the negative pressure indicator in which an internal lumen extends through the needle into the hub assembly and communicates with the lumen formed by the base of the negative pressure indicator. 
         [0072]    In embodiments including a pressure deformable diaphragm/membrane, the diaphragm may, for example be made from a thin silicone rubber membrane. The diaphragm may have an outward-(convex) biased shape (bulging outwardly, toward its cover if present), for example, dome-shaped such as hemispherical, when the internal lumen pressure (beneath the membrane into the central lumen of the hub/indicator) is at atmospheric pressure and collapsing (inward) at least partially when the pressure in the lumen is below atmospheric pressure. The diaphragm may be made by any suitable method, for example, molded (cured) in a suitably shaped, such as hemispherical shaped mold from silicone rubber. The thickness of the diaphragm/bubble membrane may, for example, be at or around 0.004 inches (0.1016 mm). An integral laterally (radially) extending circumferential flange may be provided around the base of the diaphragm/bubble for sealably attaching the diaphragm between the upper and lower parts of it housing (so that the diaphragm sealably separates the space on either of its two sides). The flange may have the same or a different thickness as the dome-shaped portion of the diaphragm member. For example, when the dome-shaped portion of the diaphragm member has a thickness of 0.004 inches (0.1016 mm), the circumferential flange portion may have a thickness of 0.02 inches (0.508 mm). The diameter of the dome-shaped portion of the diaphragm may, for example, be in the range of 0.33-1.00 inches (0.838-2.54 cm). 
         [0073]    In any of the above embodiments the proximal stylet port may be a fluid connector, such as a connector with a conical (male or female) fluid connector geometry, such as a male or female Luer connector geometry, such as a Luer slip or Luer lock geometry. 
         [0074]    Various features the invention and its embodiments are further described below with reference to the appended drawings. 
         [0075]      FIG. 1A  shows a perspective view of a hub and needle embodiment of the invention that includes a negative pressure indicator dome with a stylet inserted therein. The device includes a needle  101  such an epidural needle connected at its proximal end to the distal end of a needle hub  102 . A negative pressure indicator apparatus  105  is fittably connected to the proximal end of needle hub  102 . Indicator apparatus  105  include a transparent dome  108  communicates with the internal lumen of indicator apparatus  105  via connector tube  109  (an in turn, when the stylet is not inserted the lumen extends through hub  102  and into needle  101 ). The stylet is fully inserted into the device through the proximal stylet port of indicator apparatus  105  with stylet handle  104  surrounding and engaging the proximal end stylet port. 
         [0076]      FIG. 1B  shows an exploded view of the component parts of the embodiment shown in  FIG. 1A . Component  101  is the hollow needle (shown off-axis). Component  102  is the needle hub which has a bilateral wing structure. Component  103  is the elongate stylet member of the stylet and component  104  is the stylet handle of the stylet. Component  105  is the base body of the negative pressure indicator apparatus. Component  106  is the deformable indicator diaphragm/membrane of the indicator apparatus which has a convex dome configuration with a circumferential flange portion and component  108  is the at least partially transparent dome-shaped diaphragm cover having a hole formed therethrough at its apex. 
         [0077]      FIG. 1C  shows a medial lengthwise cross-sectional view, across the long axis of the wings of the hub, of the embodiment shown in  FIG. 1A . Stylet  103  penetrates a reversible split septum seal  107  integral with indicator apparatus  105  and extends distally through the lumens of indicator apparatus  105 , needle hub  102  and into and at least substantially all the way down the lumen of needle  101 , until stylet handle  104  is seated upon the proximal stylet port structure of indicator apparatus  105  as shown. 
         [0078]      FIG. 1D  shows a medial lengthwise cross-sectional view through the dome assembly of the embodiment shown in  FIG. 1  (perpendicular to the cross-section shown in  FIG. 1C ). Here, transparent dome-shaped cover  108  is shown covering diaphragm  106  which is convexly biased at least substantially conforming to/mimicking the shape of cover  106  (it does not need to touch the inner surface of the cover). The dome cover itself is not airtight. The space between the cover and the outward facing surface of the diaphragm is open to the atmosphere. Dome cover  108  may have one or more holes in it. Diaphragm  106  does seal the atmosphere from the volume beneath it  110  which communicates via tube  109  to the internal lumen of indicator apparatus  105 . 
         [0079]    The apparatus shown in  FIGS. 1A-1D  may be used in a method of detecting needle penetration into a negative pressure (subatmospheric pressure) space, such as the epidural space as follows. First, the apparatus as shown with the stylet securably and fully inserted therein is advanced led by needle  101  toward the presumptive negative pressure space, such as epidural space. When the practitioner determines that the needle tip is just outside the presumptive negative pressure space, the stylet is fully withdrawn from the apparatus and set aside. Upon said withdrawing, the split septum feature closes thereby sealing the internal lumen of the apparatus. The needle is thereafter carefully advanced toward the presumptive negative pressure space with a visible collapse in the diaphragm indicating that the distal tip of the needle has entered the negative pressure space. 
         [0080]    The stylet-accommodative negative pressure indicator embodiments of the invention advantageously permit the stylet to be fully inserted into the hollow needle of the hub and needle assembly with the negative pressure indicator apparatus remaining attached throughout initial tissue penetration, stylet removal and advancement of the needle toward and detection of a negative pressure space, such as the epidural space. This reduces the number of steps and manipulations that otherwise need to be performed by the practitioner, for example, in comparison to the device disclosed in U.S. Pat. No. 7,175,608. Further advantageously, these embodiments operate “dry” at atmospheric pressure, i.e., with the internal lumens air-filled rather than liquid filled and without pressurization (the devices work at atmospheric pressure). Accordingly, since the apparatus is air (gas) based, it is not sensitive to the orientation of the patient. Once penetration of the needle into the negative pressure space is detected, a catheter and/or medicaments can be administered through the indicator apparatus, needle hub and needle, into the body space. In embodiments in which the negative pressure indicator apparatus is removable from the needle hub, it may be removed and then a catheter and/or medicaments can be administered through the needle hub and needle, into the body space. 
         [0081]    In the deformable diaphragm-based embodiments, at least the inner surface of the indicator housing base may be distinctively colored (such as a dark red, blue or purple) versus the diaphragm membrane/film (which may, for example, have a whitish translucency) such that when the diaphragm collapses (inverts or flattens), the color of the housing surface become visible through the diaphragm. The inner surface of the indicator housing base may also be textured, for example with ridges such as concentric ridges which become visible upon the collapse of the diaphragm to contact the inner surface of the housing base. The surface of the base of the diaphragm may also be coated with a thin layer of lubricant such as a light oil that visibly wets the diaphragm if the diaphragm collapses and contacts the surface. 
         [0082]    The needle component of the hub and needle apparatuses of the invention may have any suitable configuration. For example, suitable types of needles for performing epidural procedures include the Tuohy needle, the Crawford needle and the Whitacre needle. Needle sizes are well known in the art and selection may vary, for example, based on age of the patient (child or adult). In general, 16-20 gauge needles may be used. 
         [0083]    The various components of the invention may be made of any suitable materials. For example, the hub and stylet handle may be made from a medical grade polymer such as a polyethylene, polypropylene or acrylic. Alternatively, the hub and stylet handle may be metallic. The needle of the hub and needle apparatus may be metallic such as made from a stainless steel. The elongate stylet member may be metallic or polymeric. Both polymeric and metallic components may be manufactured using means well known in the art such as molding, injection molding, machining, welding, joining with adhesives and combinations thereof. Various components such as the hub and stylet handle may also be manufactured using three-dimensional (3D) printing techniques, as known in the art. 
         [0084]    Each of the patent applications, patents and other publications cited in this disclosure is incorporated by reference as if fully set forth herein. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments.