SHEATH, EPIDURAL CATHETER SYSTEM, AND METHOD FOR INSERTING A CATHETER
TECHNICAL FIELD
This invention relates to an epidural catheter, and more particularly, to a sheath, an epidural catheter system, and a method for inserting a catheter tube into an epidural space in a patient.
BACKGROUND INFORMATION
An epidural catheter is typically inserted into an epidural space in a spinal column of a patient for delivery of an anesthetic for the relief of pain secondary to surgery, labor, etc. The process typically involves inserting a hollow epidural needle having a solid stylet (e.g., a thin wire inserted into the hollow epidural needle to maintain patency) through the patient's skin adjacent to the epidural space. The stylet is then removed and the epidural needle is attached to a syringe containing air or fluid. The syringe allows identifying the epidural space using the "loss of resistance" technique, i.e., the epidural needle and syringe are slowly advanced and the syringe is tested for a "bounce" in the plunger. When the "bounce" or loss of resistance in the syringe is gone, the end of the needle has entered the epidural space.
The syringe is then detached from the hollow epidural needle and a first end of a catheter tube is inserted into and fed through the hollow space in the epidural needle until the first end of the catheter exits the epidural needle and enters the epidural space. Once the first end of the catheter is positioned in the epidural space, the epidural needle is then removed from the patient by sliding the epidural needle over the second end of the catheter tube which extends from the patient so that the catheter tube remains in the patient.
The end of the catheter tube is then attached to a leur lock so that the catheter tube can be attached to a large syringe or of an anaesthetic supply pump. Typically, an antimicrobial filter is placed between the hub and the patient to inhibit bacterial migration along the catheter tube toward the exit site in the patient.
A drawback with the above-noted procedure for inserting a catheter tube in a patient is that the catheter tube is easily sheared in half by the end of the epidural needle when the catheter is pulled back through the hollow epidural needle while the needle tip remains in the epidural space of the patient. Another drawback is that this procedure requires that a physician, in order to utilize the epidural catheter, must attach the hub to the end of the catheter tube. Routinely this catheter is inserted into the hub and can subsequently become disconnected, thus, opening the catheter and patient to possible bacterial contamination.
Therefore, there is a need for a sheath for a epidural catheter system and method for inserting a catheter tube into an epidural space in a patient wherein the likelihood of shearing the catheter tube is reduced, if not eliminated, and wherein a hub may be attached to the end of a catheter tube during manufacturing prior to inserting the catheter tube into the patient. Thus creating a one piece hub/catheter system that will not disconnect. Also, such an epidural catheter system would allow the manufacturing of a catheter of various diameters as one unit, not dictated by the diameter of the epidural needle.
SUMMARY OF THE INVENTION
The above-mentioned needs are met by the present invention which relates, in one aspect, to a sheath for use in inserting a catheter tube into an epidural space in a patient. The sheath includes a generally elongated body having a first end having a point, a second end, an outer surface, and an inner surface defining a passageway extending from the first end to the second end. The body includes a slot extending
from the outer surface to the inner surface and from the first end to adjacent to the second end. The passageway is sized to allow a catheter tube to be fed therethrough, and the slot is sized to allow the catheter tube to pass therethrough.
In another aspect of the present invention, an epidural catheter system for inserting a catheter tube into an epidural space of a patient includes a sheath as noted above, a needle receivable in the sheath, and a stylet slidably receivable in the needle. Desirably, the sheath and the needle each include a beveled end, and means for aligning the beveled end of the sheath and the beveled end of the needle. The needle and the stylet may also include a beveled end and means for aligning the beveled end of the needle with the beveled end of the stylet. Advantageously, the system also includes a catheter tube having a hub attached to one end of the catheter tube.
In another aspect of the present invention a method for inserting a catheter tube into an epidural space of a patient is provided in which the method includes the steps of forming an assembly comprising a sheath as noted above having a passageway and a slot, a needle slidably received in the sheath, and a stylet slidably received in the needle. The assembly is inserted into the patient adjacent to the epidural space and the stylet is removed from the assembly. A syringe is attached to the needle and a portion of the sheath and the needle are positioned into the epidural space of the patient, e.g., using the "loss of resistance" technique. The needle is removed from the sheath and a catheter tube is inserted through the slot and fed through the passageway in the sheath and into the epidural space in the patient. The sheath is removed from the patient wherein the catheter tube passes through the slot in the sheath.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter which is regarded as the invention is particularly pointed
out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention will be readily understood from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is an exploded plan view of an epidural catheter system according to the present invention;
FIG. 2 is an enlarged, exploded plan view of the epidural catheter system shown in FIG. 1 ;
FIG. 3 is a partial, enlarged, cross-sectional view of an assembly of the sheath, the epidural needle, and the stylet shown in FIGS. 1 and 2;
FIG. 4 is a partial, enlarged, cross-sectional view of an assembly of the sheath, the epidural needle, and the glass syringe shown in FIG. 1 and 2;
FIG. 5 is a partial, enlarged, cross-sectional view of an assembly of the catheter tube inserted through the sheath shown in FIGS. 1 and 2;
FIG. 6 is a perspective view of the assembly shown in FIG. 3 prior to insertion of the assembly into a patient;
FIG. 7 is a perspective view of the removal of the stylet from the assembly shown in FIG. 6 after insertion into the patient;
FIG. 8 is a perspective view of the attachment of a glass syringe to the epidural needle shown in FIG. 7;
FIG. 9 is a cross-sectional view of the insertion of the sheath and needle,
shown in FIG. 8, into the epidural space of the patient while monitoring for the loss of resistance in the syringe;
FIG. 10 is a cross-sectional view of removal of the glass syringe and epidural needle from the sheath, shown in FIG. 9;
FIG. 11 is a cross-sectional view of insertion of a catheter tube through the slot and the passageway in the sheath, shown in FIG. 10, and into the epidural space;
FIG. 12 is a perspective view of removal of the sheath, shown in FIG. 11, from the patient wherein the catheter tube passes through the slot in the sheath;
FIG. 13 is a cross-sectional view of the assembly shown in FIG. 3;
FIG. 14 is a cross-sectional view of the sheath and the catheter tube shown in
FIG. 5;
FIG. 15 is an enlarged, partial, plan view of the sheath and key hole slot shown in FIGS. 1 and 2;
FIG. 16 is an enlarged, partial, cross-sectional view of the catheter tube (shown in phantom) inserted through the keyhole into the passageway in the sheath shown in FIG. 15; and
FIGS. 17-19 are cross-sectional views of alternative sheaths according to the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
FIGS. 1 and 2 illustrate one embodiment of a multicomponent epidural
catheter system 10 according to the present invention. In this exemplary embodiment, system 10 includes a stylet 20, an epidural needle 30, a sheath 40, a glass syringe 80, and a catheter tube 90. System 10 allows a physician, e.g., an anesthesiologist, to insert catheter tube 90 into an epidural space in a patient without requiring epidural needle 30 to be slid over the length of the catheter tube 90 when removing epidural needle 30 from the patient.
As best shown in FIG. 2, stylet 20 includes a solid, cylindrical, elongated body 22 having a first beveled end 24, e.g., a slanted or an inclined surface which defines a point 25, and a second end 26 attached to a stop 28 having a thumb rest 27.
Epidural needle 30 includes a hollow, cylindrical, elongated body 32 having a first beveled end 34, e.g., a slanted or an inclined surface which defines a point 35, and a second end 36 attached to a stop 38. Stop 38 includes a fusto conically-shaped portion 31 , a finger flange 33 and a Luer-Lock tip 37. A recess 39a in Leur-Lock tip 37 receives a tab 29 on stylet 20, e.g., when stylet 20 is slidably inserted and received in epidural needle 30 for maintaining beveled ends 24 and 34 in alignment.
Sheath 40 includes a generally hollow elongated body 42 having a first beveled end 44, e.g., a slanted or an inclined end which defines a point 45, and a second end 46 attached to a stop 48. Stop 48 includes a finger flange 43 and an conically-shaped recess 41 (shown in dashed lines). A recess 49 on stop 48 receives a tab 39b of epidural needle 30, e.g., when epidural needle 30 is slidably receivable in sheath 40 for maintaining beveled ends 35 and 45 in alignment. From the present description, it will be appreciated by those skilled in the art that other configurations may be employed to align stylet 20 to epidural needle 30, and epidural needle 30 to sheath 40, e.g., detents and/or snap-fit engaging portions.
As best shown in FIGS. 2 and 13-16, in this exemplary embodiment of sheath 40, elongated body 42 includes a sidewall having an outer surface 50 (FIG.
14), and an inner surface 52 (FIG. 14) defining a longitudinally extending passageway 54 (FIG. 14). An elongated aperture or slot 56 extends from inner surface 52 of sheath 40 to outer surface 50 of sheath 40 so that sheath 40 has a generally C-shaped cross-sectional configuration. Elongated slot 56 opens onto beveled end 44 (FIG. 2) and extends longitudinally along the length of elongated body 42 to terminated at an aperture or keyhole 55 (FIG. 2) disposed adjacent to stop 48. Desirably, sheath 40 comprises a C-shaped cross-section which defines an arc extending at least 180 degrees.
FIGS. 6-12 illustrate the procedure according to the present invention for inserting catheter tube 90 into an epidural space in a spinal column of a patient. Initially, as shown in FIGS. 3 and 6, an assembly 60 comprises stylet 20 slidably received within epidural needle 30, and stylet 20 and epidural needle 30 together slidably received in sheath 40. Stylet 20 provides support and maintains the rigidity of epidural needle 30, as well as maintains patency of epidural needle 30 as assembly 60 is inserted through a patient's skin and into the lumbar region of a patient's spine, e.g., in the ligamentum flavum, adjacent to the epidural space.
As shown in FIG. 7, once assembly 60 is inserted into the patient, stylet 20 is removed from assembly 60 leaving epidural needle 30 and sheath 40 embedded in the patient. Glass syringe 80 is attached to Luer-Lock tip 37 of epidural needle 30, as shown in FIGS. 4 and 8, to form an assembly 70 comprising sheath 40, epidural needle 30, and glass syringe 80.
Assembly 70 is further inserted into the patient, as shown in FIG. 9, using the "loss of resistance" technique, e.g., wherein a pressure is applied to thumb rest 87 to test glass syringe 80 for bounce in plunger 82. When the bounce is gone, end 44 of sheath 40 and end 34 (FIG. 2) of epidural needle 30 (FIG. 10) have entered an epidural space 12.
As shown in FIG. 10, epidural needle 30 and glass syringe 80 are removed leaving sheath 40 in epidural space 12. As shown in FIG. 11, catheter 90 is placed through keyhole 55 (FIGS. 5, 15, and 16) and fed into passageway 54 (FIG. 14) in sheath 40 and into epidural space 12. Catheter tube 90 desirably includes a hub 98 attached to end 92 of catheter tube 90. Hub 98 allows catheter tube 90 to be readily attached to a tube of a local anaesthetic supply pack (not shown). Advantageously, the tube 90 can have a greater diameter at hub 98 than the diameter of the catheter tube inserted through sheath 40 into the epidural space 12.
Once catheter 90 is positioned in epidural space 12 (FIG. 11), sheath 40 is removed from the patient as shown in FIG. 12. Desirably, sheath 40 is removed from the patient by catheter tube 90 passing through slot 56 of sheath 40. As shown in FIG. 14 slot 56 of sheath 40 is desirably sized to allow catheter tube 90 to readily pass therethrough. From the present description, it will be appreciated by those skilled in the art that hub 98 (FIG. 11) of catheter tube 90 does not interfere or prevent sheath 40 from being removed from the patient.
Desirably, hub 98 may be securely attached prior to surgery by a physician or may be fixedly attached by a manufacturer as a unit which advantageously reduces the time required for connecting catheter tube 90 to hub 98 and which reduces the likelihood of the hub and catheter tube becoming disconnected and subsequently contaminated. An antimicrobial cuff (not shown) may be manufactured to catheter tube 90 between end 92 and hub 98 if catheter is implanted into patient to prevent bacterial migration.
Also, tube 90 can be manufactured with various diameters, i.e., 20 gauge (end inserted into 12) to 10 french end 92 into hub 98. This allows for ease of handling of tube 90 with larger size by patient and professionals and allows tube 90 to be manufactured as one piece not spliced together. Lastly, by being manufactured as one piece, this eliminates need to splice catheter of various diameters together and
eliminates the possibility of the catheter coming apart or contamination thereof once implanted or utilized for patient use.
FIGS. 18 and 19 illustrate alternative cross-sectional views of a sheath 140 and sheath 240, respectively, according to another aspect of the present invention for use in the above-described epidural catheter system.
As shown in FIG. 17, another aspect of the present invention includes a sheath 340 which may include a first arcuate half 342 and a second arcuate half 344 which together form a passageway 346. By rotating first half 342 relative to 344, the arcuate halves defines a longitudinally extending slot along the length of sheath 340.
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.