Introducer apparatus with eversible sleeve

Disclosed is an introducer apparatus comprising an sleeve fixation mechanism or introducer member, such as a catheter, introducer, or ring-like structure, which is attached to a protective sleeve comprising a thin flexible material such a polymeric film. The sleeve is inverted into the passageway of a second member, such as a catheter, feeding tube, introducer, etc., that is advanced through the passageway of the introducer member and is introduced into a bodily passage of a patient, such as the bile duct, nasal passages, colon, etc. The sleeve everts from the passageway of the second member during its advancement to lay down a friction-reducing surface. The sleeve prevents frictional contact between the second member and delicate or sensitive tissues.

TECHNICAL FIELD

This invention relates to medical devices, more particularly to catheters introduced into body lumens.

BACKGROUND OF THE INVENTION

Despite the efforts of medical device manufacturers to reduce the coefficient of friction for their catheters, especially those intended for introduction through a sphincter or narrow body lumen, there is very often a problem with discomfort to the patient or trauma to delicate or sensitive tissues as the catheter is being advanced. Lubricants and lubricious polymers or other coatings can reduce these effects, but not always to a sufficient degree. In the biliary system, for example, passing a biliary catheter through the Papilla of Vater and into the common bile duct very often results in swelling and subsequent closure of the opening, compromising normal drainage and making subsequent access difficult. Similar problems with discomfort or edema can be experienced by the patients when other anatomical sites are being accessed, for example, in the nasal passages, urethra, rectum, etc. While patient comfort may not be an issue when navigating internally such as within the biliary tree, the introduced device may be difficult or even impossible to advance from frictional forces acting against it, especially since these obstructions and narrowed passages often cannot be adequately visualized.

One approach to reduce patient discomfort when introducing a catheter or similar device, is to include a sheath or sleeve which is laid down by the advancing device to prevent frictional contact between the device and the delicate lining of the bodily passage. A urethral catheter with an outer sleeve is disclosed in U.S. Pat. No. 5,779,670 to Bidwell in which the latex sleeve is fixedly and sealingly attached to the inside of the catheter by a sliding retention sled and to the outside of the catheter by a slidable collar. The sleeve allows relative movement of the catheter to the urethra without the normal friction that causes patient discomfort during introduction and wearing of the device. A lubricant fills the space created between the sleeve and the catheter which is intended to further reduce friction between the two surfaces. While the '670 concept may be suitable to traverse the urethra for purposes of draining the bladder, it is not useful for other anatomical sites and procedures in which having the sleeve attached to the inside of the catheter is not desired, such as in an ERCP (Endoscopic Retrograde Cholangiopancreatography) procedure or placement of a nasal-jejunal feeding tube or colonic decompression catheter. In these procedures, the sleeve might be used advantageously in combination with the introduced device to access a narrow duct or opening, to cannulate a stricture, or navigate over folds of tissue, but its eventual removal from the inner member passageway is typically required to complete the procedure. In the case of a feeding or decompression tube, continued presence of the sleeve over the catheter would block critical side holes. For these reasons, the Bidwell concept is not suitable for the introduction of a second medical device into the body.

Besides the biliary system, other sites within the body present an opportunity for improved patient comfort and reduced trauma by the reduction of friction during the introduction of a device. For example, the nasal passages are especially sensitive and recent trends have brought about an increase in the number of devices, such as endoscopes and tubes, being introduced via that route concomitant with the use of analgesics or sedatives to reduce patient discomfort. Another situation where reduction of friction would be important is in the lower gastrointestinal tract where folds within the colon can provide sufficient resistance to an introduced catheter or other device where in many cases, the tip of the catheter bends back on itself, rather than continuing to advance to the treatment site. Therefore, what is needed is a friction-reducing introducer apparatus that can be used with a separate catheter, sheath, or other medical devices to permit the safe and comfortable passageway thereof into and/or through a bodily passage, and is removable from the treatment site so as not to possibly interfere with the function of the introduced device(s).

SUMMARY OF THE INVENTION

The foregoing problems are solved and a technical advance is achieved in an apparatus for introducing a second medical device, such as an inner member or an elongated member, into a bodily passage, the introducer apparatus comprising a sleeve fixation mechanism, such as an introducer member. The sleeve fixation mechanism facilitates engagement of the sleeve with the opening of the bodily passage and can include a variety of structures, such as an introducer sheath, tube, ring-like member, barbs, or other structure which is permanently or releasably attached to a full or partial sleeve which is made of a thin, flexible material. The sleeve, which can be made of variety of biocompatible materials such as expanded polytetrafluoroethylene (ePTFE) or polyethylene film, is sufficiently flexible to be made eversible or such that one end can be inverted back through the passageway of an introducer member and loaded into the passageway of a second member, such as a catheter, that functions as a coaxial inner member and also serves as the medical device being introduced into the bodily passage. The inverted sleeve is then pulled from the inner member passageway and laid down within the bodily passage or the opening thereto by the inner member as it advances out of or through the introducer member, which is typically maintained in a nearly stationary position and generally does not enter the target bodily passage, although, such as in the case of a biliary catheter, may be introduced through other body lumens to position the inner member at the opening to a remote bodily passage.

As a result of the cooperation between the sleeve, the introducer member, and the inner member, neither the sleeve nor the inner member frictionally slides against the bodily passage during advancement, thereby providing improved patient comfort and/or facilitating forward movement which may reduce trauma to the sphincter, duct or body lumen through which it is being introduced. In addition to reducing friction, the sleeve can act to provide a smooth track over an uneven surface, such as the tissue folds that occur within the Papilla of Vater or the intestinal tract. The sleeve is designed to be completely or functionally eversible at full deployment from the inner member passageway (maximum extension of the inner member relative to the sleeve), such that the passageway of the inner member can be at least substantially cleared and be functionally unobstructed. Typically, but not essentially, the second end of the sleeve is unattached to the inner member; however, if it attached, it has the ability to substantially clear the passageway such that the sleeve or attachment does not interfere with the passage of devices or materials through the inner member. Partial deployment of the inner member, which may also be desired in some applications, can result in a portion of the sleeve still remaining in the inner member passageway. In addition to making it simpler and cheaper to manufacture, leaving the second end unattached, makes it easier to remove the introducer assembly from the patient while maintaining the inner member in place. Additionally, it allows the passageway of the inner member to be free of obstructions and have a maximum possible diameter for passage of other devices, once the sleeve has completely everted. Alternatively, the sleeve may also be attached to the inner member in a manner, such as around the distal tip, that the sleeve can evert out of the passageway to a sufficient degree as not to interfere with the passage of a third medical device, such as a endoscope, through the inner member conduit. Attachment of the sleeve, while substantially maintaining the patency of the passageway, would be functionally equivalent to having an unattached and fully-eversible sleeve, and thus, fall within the scope of the present invention.

In another aspect of the present invention, the introducer apparatus is adapted to permit the inner member to laterally deflect as it advances from the introducer member and causes the sleeve to evert. This can be accomplished by the addition of an asymmetrical tip to the inner member or making the inner member itself asymmetrical such that the sleeve has more drag on one side, thereby causing the inner member to deflect in that direction. This property is advantageous in certain clinical situations such as in the biliary tree where there is a bifurcation between the bile and pancreatic ducts. Another means of causing the inner member to deflect in a given direction is to modify the sleeve such that one side has a greater coefficient of friction than the other. This can be accomplished by removing a portion of sleeve longitudinally to make a half sleeve, making the sleeve out of two materials, or treating one half of the sleeve such that the half having a greater coefficient of friction causes the inner member to bend in that direction as it advances through the bodily passage.

In still another aspect of the present invention, the introducer member and sleeve are made splittable with a predetermined split line such that they can be removed from over the inner member within the patient, without requiring its removal or causing its dislodgement. Other methods of removing the introducer member from the inner member include making the inner member twice as long as the outer so that is can be removed from the patient and left over the external portion of the indwelling inner member, or having a removable/replaceable connector on the inner member so that the introducer member can be removed over the proximal end of the inner member.

In yet another aspect of the present invention, a tether is affixed to the second (inverted) end of the sleeve for reloading the sleeve once it has partially everted. The attachment may be such that the sleeve passageway is maintained in an open state to facilitate access by other medical devices, such as a wire guide, being introduced therethrough. This can include a reinforcing annular ring within or external to the second end of the sleeve and/or a second tether.

In still yet another aspect of the present invention, the introducer apparatus can include means for reducing friction between the sleeve and inner member during its use. One embodiment includes folding or pleating the sleeve to shorten it within the passageway and reduce the amount of contact with the inside of the inner member passageway. This pleated sleeve unfolds as it is everted by the advancing inner member. Another method is to modify the distal end of the inner member to reduce friction. Besides changing the surface energy of the tip, including adding a second more lubricious material, the tip can be made to ease frictional movement of the sleeve by the addition of ball bearings or rollers to the tip which rotate as the sleeve is passed thereover.

In still yet another aspect of the present invention, the introducer member comprises a short annular ring or collar that is slidable over the inner member that is being introduced therethrough, rather than an elongated introducer catheter. This embodiment has utility when directly accessing the target bodily passages from outside the body such as when placing nasal-gastric or nasal-jejunal feeding tubes, colonic decompression catheters, and urethral catheters, etc. In these types of procedures, the operator can grasp the outer ring directly adjacent the introduction site and deploy the inner member, rather than to first navigate the introducer apparatus to a remote location in the body, such as the Papilla of Vater and common bile duct. The outer ring can also be provided by forming a thickened portion of the sleeve material at or near the first end of the sleeve.

In still yet another aspect of the present invention, either the introducer member or second member can include additional lumens for passage of other devices or injection of materials such as contrast agents with one passageway receiving the eversible sleeve and at least one other adjacent passageway remaining free to serve a different function. Contrast media, as well as other agents, can also be introduced through the sleeve itself via a plurality of apertures in the material, such as a mesh.

In still yet another aspect of the present invention, the introducer apparatus can be placed over a nasal-gastric (NG) tube, or other medical device such that the inner member comprises a cap-like structure with the sleeve everting from within the lumen of the inner member which frictionally protects the bodily passage from the NG tube and advancing inner member. The sleeve everts from a distal chamber in the inner member which is separated by a proximal receiving chamber housing the distal end of the NG tube by a partial septum. The introducer member ring is tethered to the inner member for pulling the inner member proximally over the inner NG tube, allowing the latter to advance through the partial septum and out of the inner member for final placement.

In still yet another aspect of the present invention, the inner member of the introducer apparatus is made radially expandable such that once it is introduced into the body, e.g., the back of the throat for placement of an NG tube, the sleeve is removed and a larger device (the NG tube) can be introduced therethrough as the inner member expands to accommodate its passageway. Embodiments of this concept include having the inner member comprise a cut, rolled tube with overlapping edges that allow for its expansion, and an inner member having a folded pleat on one or more sides that permits limited expansion of the introducer during passage of a device such as an NG tube.

In still yet another aspect of the present invention, the inner member includes a fluid reservoir, such as a bottle for delivery of an enema. The outer member comprises a ring-like structure that slides over the neck of the bottle, the neck utilizing the eversible sleeve to reduce patient discomfort when traversing the anal sphincter as the outer member ring abuts the peri-anal area.

DETAILED DESCRIPTION

The present invention comprises an introducer apparatus10for reducing friction of a medical device being introduced into a bodily passage26, a first embodiment of which is depicted inFIGS. 1-4. The introducer apparatus10comprises an introducer assembly11that includes a sleeve fixation member12, such as the illustrative introducer member, having a passageway20therethrough and a flexible sleeve13comprising a body76, a first end25and a second end64. The sleeve13also includes a first portion106and a second portion107(FIG. 4), with the first portion106, which includes the first end25, being attached about the introducer member by an attachment14which preferably, but not essentially, affixes the sleeve13at one or more attachment points110to the outer surface75of the introducer member12and is fixed against movement with respect to the introducer member12. Although the sleeve13is typically attached to the introducer member12at the ‘true’ first end25thereof, it is possible that the sleeve13may also extend proximally beyond the attachment14such that the attachment14lies within what technically, could be considered the body76of the sleeve13; however, functionally, the first end25would still occur at the point of attachment110, especially if fixedly attached, regardless of whether unattached sleeve13material extended proximal to that point.

The sleeve13should be made of a material that allows it to be sufficiently flexible to conform to the shape of a device being placed therethrough. For most applications, the material, which is typically thin, should exhibit resistance to tearing and stretching (i.e., have good linear strength). Generally, the sleeve should be smooth and lubricious such that the sleeve, as it is laid down by the advancement of the device, or being withdrawn from the body, is atraumatic to delicate linings of the body, such as sphincters, tissue folds, ducts, and other passages. One material with particularly desirable properties is expanded polytetrafluoroethylene (ePTFE). Custom extruded ePTFE, which is available from Zeus Medical Products, Inc., Orangeburg, S.C., is produced from polytetrafluoroethylene (PTFE) tubing that is expanded under controlled conditions which advantageously adds microscopic pores throughout the material. The result is a soft, flexible material with increased linear strength. The wall thickness of the sleeve13depends largely on the application and material used and may typically range from 0.001-0.01″ for ePTFE. A more preferred range for ePTFE when introducing a standard ERCP device would be in the 0.002-0.005″ range, most preferably around 0.0025″. Many other polymeric films, such as high-density or low-density polyethylene, have desirable properties, particularly those with adequate linear strength. Their lower cost can be significant, particularly for longer devices. Other possible materials include latex, woven fabrics, or biomaterials that can be fabricated into a thin, flexible sheet or tube of sufficient strength. The sleeve can also be coated or impregnated with other compounds and materials to achieve the desired properties.

To achieve an attachment14between the sleeve13and introducer member12, a variety of well-known methods can be used. Permanent bonding methods include, but are not limited to, a wrapping, such as with a thread or suture material; heat shrink wrap or tubing; thermal, laser, or ultrasonic welding; an adhesive, or a combination thereof. A detachable means of securing the sleeve can also be used, such as a ring, collar, elastic band, channel/groove, lower-grade adhesive, or another well-known means. In the illustrative embodiment, the single point of attachment110extends around the circumference of the outer surface75of the introducer member12; however,FIGS. 18-18Adepict an embodiment having more than one point of attachment110between the sleeve13and introducer member12. The introducer member12can also be integrally attached to the sleeve13, thus forming an arrangement of unitary construction.

As shown inFIGS. 1-4, the introducer assembly11is intended for use with a separate second member15, hereafter referred to as the inner member, that is introduced through the passageway20of the introducer member12and into a bodily passage26(FIG. 4), such as the common bile duct or other passage. This inner member15can include any of a number of medical devices such as catheters, introducer sheaths, cannulae, stents, endoscopes, retrieval or surgical devices, etc. A portion of the sleeve body76, referred to herein as the second portion107, resides within the passageway22of the inner member15as the inner member is introduced into the bodily passage26. The first portion106of the sleeve13is generally defined as that part of the sleeve body76that typically remains outside of the inner member passageway22after the sleeve13has been loaded. The second portion107is typically inverted or preloaded into the passageway22with that portion of the sleeve being eversible from the passageway22as the inner member15is advanced relative to the introducer member12, to which the first end25of the sleeve13is attached. As used herein, the terms ‘evert’ or ‘eversible’ refers to the process by which the sleeve13unfurls, unfolds, invaginates, or otherwise exits the passageway22into which it resides, upon which time the sleeve13turns back on itself and conforms over the outer surface of the inner member15, forming a barrier between the inner member15and the inner surfaces28of the bodily passage36.

The overall length of the second portion107is largely determined by how far the inner member15is typically advanced into the bodily passage26during a particular procedure. The second end64of the sleeve is either completely unattached to the inner member15as it resides in the passageway20, or is releasably secured in a manner such that the second end64is completely eversible from the passageway22of the inner member if necessary or so desired. Movement of the inner member15relative to the introducer member12is therefore, not normally limited by the length of the sleeve13and the introducer member12, and the sleeve13can be removed from the patient or treatment site separately from the inner member15once the sleeve13has completely everted from the passageway22. The introducer member12can comprise an elongate catheter, as shown in the illustrative embodiment, that houses the inner member15, or it can be much shorter in length, as shown in later examples.

The length and shape of the sleeve can be quite variable, depending on the application. In the illustrative embodiment ofFIGS. 1-4, which is used as a biliary catheter for an ERCP procedure in an adult patient, the sleeve is tubular and typically measures from 6-10 cm in length, preferably 7-8 cm, so that the inner member can cannulate both the opening of the duct and any strictures that may exist therein. Preferably, it should not be so long that it cannot completely evert from the inner member15during the procedure, since in this particular embodiment, removal of the sleeve is desired after the inner member is in position. Other procedures may require a longer sleeve13. For example, the sleeve13used to introduce a standard feeding tube, e.g., a nasal-gastric (NG) or nasal-jejunal feeding tube, would be more in the 20-40 cm range, more preferably around 30 cm. The sleeve13is used to protect the feeding tube through the nasal passage past the deviation of the septum until it reaches the back of the throat where natural peristalsis takes over and helps to urge the feeding tube downward through the esophagus and into the stomach or jejunum. To assist natural peristalsis, the sleeve13or other portion of the introducer apparatus10can be provided with a surface structure having a bidirectional coefficient of friction such as disclosed in a pair of co-pending applications, both entitled, “Medical Instrument Having Bidirectional Coefficients of Surface Friction,” U.S. Ser. No. 08/989,413, filed Dec. 12, 1997 and U.S. Ser. No. 09/184,331 filed Nov. 2, 1998.

A shorter sleeve, e.g., 7-10 cm may be desired for nasal introduction if the inner member is merely serving as a short conduit for the subsequent introduction of another device, such as an endoscope, therethrough. The second device can then be introduced much more comfortably than would be otherwise possible. Conversely, a much longer sleeve, e.g., 150-160 cm, might be used for a colonic procedure. Ideally, the sleeve for a particular application, should be properly sized such that it completely everts from the inner member, if so desired, to allow it to be removed while maintaining the inner member within the patient.

Continuing with the first embodiment,FIG. 2depicts an introducer member12that is an elongated catheter in which the sleeve13has been completely inverted into the passageway22of the inner member15which in turn, coaxially resides within the passageway20of the introducer member12. As shown inFIG. 3, the inner member15advances relative to the introducer member12with the distal end36or leading edge of the inner member15urging the sleeve13forward and thereby, pulling it out of the passageway22into which it has been loaded.

FIG. 4show the introducer apparatus10being used within a patient. The introducer member12is positioned at the opening27of a bodily passage26into which the inner member15is to be introduced. Holding the proximal portion77(FIG. 1) of the inner member15in place, the introducer member12is then urged in a proximal direction. Typically, this action causes the sleeve13, which sheaths the distal end36of the inner member, to grip the surface of the passage opening27, thereby ‘self-advancing’ the inner member15as the introducer member12is ‘retracted’ (as shown). In these instances, the introducer member12does not actually move any significant distance from the opening, despite the rearward force be applied, but rather, the inner member15is advanced forward into the bodily passage26although it is not actually being directly advanced by the operation. Thus, the inner member15is described as ‘self-advancing.’ In selected embodiments or certain instances, the operator may need to directly advance the inner member15in order to have the sleeve13evert and lay down a protective track; however, the sleeve still provides the same protective function. For each of the illustrative embodiments, the sleeve13lays down a track, much like the way a military tank or bulldozer moves, such that the advancing inner member15frictionally slides against the protective sleeve13itself instead of directly contacting the lining28of the bodily passage26. Because the sleeve13does not slide against the internal lining28of the bodily passage26, there is minimal irritation and trauma to the opening27and bodily passage26during its initial introduction. The sleeve13protects the bodily passage26for a distance up to its own length, after which, it completely everts from the inner member15and any further advancement will typically result in normal frictional contact between the inner member15and the bodily passage26. In the case of the biliary tree, it may only be important to provide protection for a short distance to traverse the Papilla of Vater, or it may be necessary or desirable to extend this protection further into the duct such as to cannulate a stricture. For certain applications, the sleeve13should completely or functionally evert from the passageway22of the inner member15, or a particular application may not require that it does so.

With respect to the embodiment ofFIG. 1, which is configured for accessing the biliary tree, the introducer member12should be at least 150 cm for an adult patient, typically 157-160 cm. The introducer member12normally must be removed from the patient while the inner member15remains in place. To accomplish this, the inner member15is made at least twice as long as the introducer member12such that the entire length of the introducer member12can remain over the inner member15and extend outside the patient. This is especially useful when there is a proximal connector21on the inner member15of this embodiment which may not permit removal of the introducer member12thereover. The proximal connector21, such as a luer fitting, is useful in this embodiment because the injection of contrast media, which would be infused through the inner member15, is typically important in ERCP procedures. A removable connector may be used, such as a Tuohy-Borst adaptor, that can be unscrewed and removed to allow removal of the introducer assembly11, then reattached. A reattachable proximal connector21is particularly advantageous when the inner member15is made long (e.g., 400 cm) to allow the introducer member over the inner member, which remains in place within the patient. Once the introducer member12is discarded, the long inner member15can be cut to a more manageable length (e.g., closer to 200 cm) before replacing the proximal connector21.

In certain clinical procedures, it is advantageous to be able to direct or deflect the tip of the inner member as it is being advanced into the bodily passage, for example, to negotiate a particular branch when confronted with a bifurcation.FIGS. 5-10depict various means of causing the inner member15to deflect in one particular direction over the other. In the embodiment ofFIG. 5, a separate distal tip29is affixed at the distal end36of the inner member15. As depicted, the distal tip29is configured to be an asymmetrical-shaped tip30which includes a proximal portion34that is inserted into the passageway22of the inner member and a distal portion33that forms the leading edge of the inner member15. The distal portion33of the asymmetrical-shaped tip30is divided longitudinally into a first side31and a second side32. In the illustrative example, the first side31is considerably more rounded than the flattened second side32. As a result, the enlarged first side31provides more drag against the sleeve13than the second side32as the sleeve13is everting out of the inner member15, which in turn, causes the distal end36of the inner member15to laterally deflect toward the direction corresponding to the first side31.

FIG. 6depicts a laterally deflectable embodiment of the present invention accessing the bile duct. When the introducer11is advanced from an endoscope78and placed at the Papilla of Vater27, the opening to the common bile duct26, there is a marker69that indicates the direction in which the inner member15will deflect. To accomplish this, it is essential that the inner member15and introducer member12be aligned such that the means for deflection, whether part of the inner member15or the sleeve13, is aligned with the marker69printed on the sleeve13or introducer member12. This can be done by providing guide marks (not shown) on the proximal area of both the outer and inner members12,15such that they can be rotated into alignment prior to advancement of the inner member15. Once alignment has occurred and the position of the marker69is established endoscopically, the inner member15is advanced into the common bile duct26where it deflects into the bile duct37as desired, avoiding the pancreatic duct38. To access the pancreatic duct38instead, the introducer assembly10would be simply rotated such that the marker69is positioned approximately 180° in the opposite direction. Alternate methods of providing a visual marker on the sleeve13would be to place a radiopaque marker on either the sleeve13, the inner member15or the introducer member12such that the orientation of the asymmetrical tip30can be determined under fluoroscopy when contrast media is injected into the biliary tree. It should be noted that the natural folds of tissue105just inside the common bile duct26may be utilized to help provide increased grip on the sleeve13, thereby pulling the inner member15preferentially toward the bile duct37branch.

Besides incorporating a separate asymmetrical tip30to cause the advancing inner member15to deflect, as shown inFIG. 5, the distal end36, or the region thereabout, of the inner member15itself can be configured (FIGS. 7-8) to provide unequal drag between the different sides31,32of the inner member, thereby causing the sleeve13to pull the inner member15laterally in a particular direction as it advances. In the embodiment ofFIG. 7, the first side31of the inner member15includes a lateral protuberance41that increases resistance to the sleeve13passing thereover. The resistance differential relative to the second side32, which lacks a protuberance41, causes the inner member to deflect toward the first side31. In the embodiment ofFIG. 8, the distal end36of the inner member15includes a bevel42to provide different degrees of resistance to the sleeve13between the first side31and the second side32of the inner member. The long second side32of the bevel42provides increased resistance over the first side31, therefore causing the sleeve13to deflect the inner member15in that particular direction.

In addition to modifying the inner member15to achieve controlled directionality during its advancement, the sleeve itself13can be modified to achieve similar results. InFIG. 9, a sleeve is shown having a distal portion79that is tubular in shape and a proximal portion80in which the material on one half is removed to create a partial sleeve43which is semi-circular in cross-section during deployment of the apparatus10. In this design, the full sleeve13or distal portion79is used to cannulate the opening to the bodily passage, whereby as the partial sleeve43portion everts, a situation is created in which there is a friction differential between the two sides31,32of the inner member15that results in the inner member15being laterally deflected in the direction of the open portion81of the sleeve13. Another means of accomplishing this effect is depicted inFIG. 10whereby the sleeve is divided longitudinally into two halves44,45, each having different properties. In the illustrative embodiment, the first half44of the sleeve comprises a porous material with a plurality of apertures109, such as a fabric mesh, while the second half45comprising a material more suitable for friction reduction. One purpose of the porous material would be allow contrast media to be pushed through the apertures109into the bodily passage to improve imaging of the target site for diagnosis or treatment. A large open mesh, e.g., 0.02-1.0 mm, would also allow drugs to be infused into the bodily passage. The amount of porous material can range from a narrow longitudinal strip, to an area comprising the majority of the circumference of the sleeve13. Another clinical application for a large open mesh would be for obtaining cytology samples, whereby withdrawal of the sleeve within the bodily passage traps cells within the apertures109in the mesh and allows the cells to be collected for laboratory analysis.

In another variation of the embodiment ofFIG. 10, the two halves44,45of the sleeve13can given a different coefficient of friction, which causes the sleeve to deflect toward either the first side31or the second side32, depending on which half of the sleeve44,45offers the most resistance against the inner member15as the sleeve13as it is being everted. The first and second sleeve halves44,45can either be made of different materials that are joined along the longitudinal axis by an appropriate means such as stitching, welding, gluing, etc., to form a tubular composite sleeve13, or a sleeve13of a single material can be treated to increase the coefficient of friction on one side. For example, the material could be mechanically or chemically roughed to increase friction; a second material, such as silicone beads, could be applied to the surface to increase friction; or a lubricious material could be added to reduce friction on a particular side.

Another means of adding directionality to the introducer apparatus10is to incorporate a desired amount of curvature to a component thereof during its manufacture.FIG. 23depicts an introducer apparatus10in which the introducer member12has been preformed with a particular curvature to improve accessibility to a target site in certain clinical situations. It might be desirable to limit the curvature to the very distal portion or the curvature might extend over a greater portion of the inner member15. The inner member15itself can be preformed with a curvature as well, as depicted inFIG. 24to aid in certain procedures, especially an ERCP, where the ability to successfully navigate a bifurcation may be required. In the illustrative embodiment, the introducer member12has sufficient integrity relative to the inner member15(i.e., stiffer materials, increased wall thickness, etc.) that it acts to constrain the curved inner member15into a straight configuration, wherein the inner member assumes its predetermined shape upon advancement from within the introducer member12. In another embodiment, the curved inner member15would force the otherwise straight introducer member12to assume the inner member's predetermined shape. In still another embodiment, both the inner member15and introducer member12can be both given a predetermined curvature, which may approximately match that of the other. One result of added curvature to both the outer and inner member12,15would be to allow for an overall double curvature wherein the introducer member12permits a lateral access in one direction, while the advancing inner member15can positioned such that it deflects back in a second direction (e.g., an S-curve). It should be noted that in some applications, such as an ERCP procedure, the inner member15must be made sufficiently flexible to bend back on itself when it cannot find a suitable passageway, thereby not creating a false passage. Other methods for curving the inner member15include having the sleeve13extruded such that it includes curvature of its own. If the sleeve13has sufficient linear strength or stiffness and the inner member15is sufficiently pliable, the curved sleeve13would force the inner member15to deflect in the direction of the curvature of the sleeve13, much like the example depicted inFIG. 24which is also provided to illustrate a pre-curved inner member.

FIG. 34depicts another sleeve configuration for preferentially directing the inner member15, whereby the sleeve13is extruded or shaped such that one half44includes pleat or folds55, while the other half45is of the typical smooth, cylindrical shape. Under selected conditions, the inner member15would generally tend to deflect in the direction oriented with the second, smooth half45of the sleeve.

As discussed, using the present invention in certain types of procedures may require that the introducer member12and sleeve13be removed from the patient, or at least from around the inner member15, while the inner member15remains in place. In addition to making the inner member15such that the introducer member12can either be removed over the proximal end19(i.e., a detachable hub) or the inner member is at least twice as long as the introducer member12, another methods would include making the introducer member12and sleeve13splittable as depicted inFIG. 11such that they can be peeled back from the proximal end19and removed without requiring disruption to the inner member15. One preferred material for a splittable introducer member12is molecularly oriented (non-isotropic) polytetrafluoroethylene (PTFE), such as that used in the PEEL-AWAY™ Introducer Sheath (Cook Incorporated, Bloomington, Ind.). The advantages of the material is that it does not require a prescored line and as it is being split open as the progressive tear maintains a straight and predictable pathway. At the proximal end19of the introducer member12, the sheath has been modified to comprise two opposing ears83or tabs that are divided by opposing cut points84. The operator grabs the ears83and pulls them apart from each other, starting the split at the cut points84. Once the splitting action has commenced along opposing predetermined split lines47, it progresses distally as the two halves of the introducer member12sheath are pulled apart. Depending on the design, the split continues through the sleeve attachment14and splits the sleeve13, which may include a tear line46such as a perforation, or the split may stop at the attachment point or sleeve and the operator will then manually split the remainder of the introducer assembly11that is now outside the patient, such as with a scalpel, taking care not to nick the inner member15. A third method of removing the introducer member12from over the indwelling inner member15is depicted inFIG. 27. The introducer member12includes a longitudinal opening74or split extending the length of the introducer member12through which the inner member15can be removed from the passageway20thereof. The introducer member12can then be removed from the patient while the inner member15remains in place.

FIG. 12depicts an embodiment of the present invention in which the sleeve13is reloadable by use of a tether48attached to the second end64of the sleeve13and where the attachment point49includes a knot or other means to secure the tether48to the sleeve13. The sleeve13remains basically eversible from the passageway22of the inner member15; however, the inner member15is limited in it's forward movement once it does. The everted sleeve13can advantageously retrieved by grasping the accessible portion of the tether48and pulling in a proximal direction. This pulls the sleeve13back into the passageway22whereby the sleeve13again becomes inverted into the inner member15, making available to be used again, if necessary or so desired. To maintain patency of the sleeve13, the embodiment ofFIG. 13includes a tether48where the attachment point49to the sleeve13is located along only one side of the second end64such that the sleeve passageway24remains in an open condition and thus, better able to receive a wire guide, deliver contrast media, etc. A second tether52and attachment point50can be added to add stability and maintain patency as depicted inFIG. 14. An annular ring51can further serve to hold the sleeve passageway24open and provides an anchoring point for the attachment points49,50of the respective tethers48,52. If the annular ring51, is made of an elastic materials, it is possible for the inner member15to push through the annular ring51and not be limited advancement of the inner member15, especially if the annular ring51is given a larger diameter than the inner member15and compressed within the passageway22. If not, the ring51will typically stop at the distal end36of the inner member15, limiting the further advancement thereof.

FIG. 15depicts an embodiment of the present invention in which the sleeve13is configured to include a series of pleats55, resulting in the body76of the sleeve13become somewhat accordion-shaped while inverted into the passageway22prior to deployment. The pleats55permit the sleeve to unfold and expand longitudinally as it everts. This can be especially useful when the eversible sleeve must extend over a considerable distance, such as for a small bowel nasal feeding tube which can be 150 cm in length. The primary value of folding the sleeve to reduce its length is to provide less drag between the sleeve13and the inside of the inner member passageway22, since a long sleeve13is more difficult to pull out of or load into the inner member15due to the increased frictional load.

FIGS. 15-17show a modification of the apparatus10in which the introducer member12, rather than comprising a elongated tube, is an external ring53or carriage-like structure that is slidable with respect to the inner member15that is to be introduced into the bodily passage. As shown inFIG. 16, the external ring53can optionally be prevented from being removed from the distal end36of the inner member by inclusion of a stop54that is incorporated into the inner member15. Additionally, the external ring53can include at least one projection92that fits within a groove93on the inner member15such that the external ring53cannot twist or rotate relative to the inner member15which could also result in the twisting of the sleeve13. In its simplest form, the external ring53can be made integral with the sleeve13material such as by forming a thickened portion thereof at or near the first end25of the sleeve13. Having the introducer member12comprise a relatively short external ring53rather than an elongated tubular member is preferable, or at least possible, in applications where the entire introducer member12is outside the patient's body, or nearly so, such as a nasal tube or urinary catheter introduction, or when accessing the lower gastrointestinal tract via the rectum. In these instances, the clinician can grasp the external ring53which generally abuts the introduction site, whereby the inner member15spontaneously advances or is manually advanced into the bodily passage. In a remote access situation as with the biliary system, the introducer member12must be sufficiently long such that the proximal end19is outside the body (FIG. 1) so that it can be manipulated from that point, rather than from within the duodenum.

In a related embodiment shown inFIG. 37, the inner member15comprises a container115, such as a bottle, used to supply fluid used in the administration of an liquid agent, such as to perform an enema. The bottle115includes a proximal reservoir portion116which narrows distally to form a neck portion117that is inserted into the patient. The introducer assembly11includes the sleeve13, the sleeve attachment14, and outer member12, which in the illustrative embodiment, comprises a ring-like member53with a proximal collar. The ring-like member53is sized larger than the anal orifice118and is designed to abut the peri-anal area119. The illustrative embodiment is configured for self-delivery whereby the patient gently inserts the distal tip36of the bottle (covered by forward edge of the sleeve17) into the anal orifice118. The sleeve13, provided to reduce friction and discomfort caused by the insertion of the bottle115, then spontaneously everts as the neck117of the bottle is drawn through the anal sphincter121into the rectum where the contents of the bottle115are delivered. The wider reservoir portion116can provide a stop to ensure that the neck portion117traverses the anal sphincter121without extending too far into the rectum120. The sleeve13can either be unattached within the interior passageway22of the bottle115or be eversible by attaching to the inner member15in a manner such that it does not obstruct fluid flow therethrough (i.e., glued or otherwise bonded against the passageway22wall or about the distal end36. It is not necessary to attach the ring member53to the bottle115, which can be packaged together with plastic wrap or some other means to both keep the apparatus sterile and maintain the ring member53in a fixed pre-delivery position. At deployment, the neck117of the bottle advances through the ring member53, which is held stationary against or adjacent to the peri-anal area119. The same concept, i.e., container115with eversible sleeve13, can be applied for delivery of therapeutic agents via the nasal passages or elsewhere in the body and maybe include a syringe, bag, pump, or other container adapted to hold and deliver a liquid, gas, or a suitably formulated solid material. The neck portion117may comprise various shapes and materials depending on the desired application.

FIGS. 18-18Adepict an embodiment wherein the introducer member12, rather than being a coaxial outer tube or ring, comprising a pair of longitudinal attachment strips56, such as flat wires or strips of material, that reside in opposing grooves57or channels formed into the outer surface of the inner member15, and through which the inner member15passes as it advances into a bodily passage. The attachment strips56are secured to two oppositely oriented attachment points along the sleeve13with an attachment mechanism14such as adhesive, stitching, etc., or they are tightly biased against the sleeve13such that when the attachment wires56are retracted by the operator, the inner member15advances through the bodily passage until the sleeve13fully everts. The attachment wires56may then be fully retracted along and within the grooves57to completely remove the sleeve13from the patient. Optionally, the attachment strips56can be conjoined at or near their proximal ends or to allow them to be retracted at the same rate. In should be noted that the number of longitudinal attachment strips56is not critical to the invention. Furthermore, the embodiments ofFIGS. 18-18Ashow that the sleever fixation mechanism12or introducer member need not be a tubular or an annular structure, but rather, can include any structure or series of structures, including an array of barbs or other fixation devices, that can attach about the first end25of the sleeve and maintain the first portion106of the sleeve outside the opening of the bodily passage, while facilitating the introduction of the inner member15thereinto. For example, barbs or other structures of similar function can be configured to engage tissue about the opening of the bodily passage to facilitate introduction of the inner member, then disengage when the sleeve13is to be discarded. In this sense, the array of barbs collectively form the sleeve fixation mechanism12, which can also be defined as the introducer member, with the inner member15being advanced therethrough.

FIG. 19depicts an introducer apparatus that can be used with a third member or device59, such as nasal-gastric (NG) or nasal-jejunal (NJ) feeding tube, endoscope etc. of various sizes. Such devices can be introduced while having the benefit of the protective sleeve, yet without the sleeve directly cooperating with the third device59. In the illustrative embodiment, the introducer member comprises an external ring53and the sleeve13inverts into an inner member15that is separate from the third device59. The inner member15acts as a distal cap that fits over the distal end96of the third device59being introduced. The inner member15can be advantageously made of a resilient material, such as silicone, such that it can stretch over the third device59that is inserted thereinto, although less-resilient materials can be used if tight cooperation between the second and third members15,59is not necessary. The inner member15comprises a distal sleeve chamber60that houses the loaded sleeve13, and a receiving chamber70into which the third device59is inserted. The medical device59is advanced through the introducer member12(external ring53) and into the receiving chamber70until it abuts the chamber septum65which divides the two chambers60,70. The external ring53has a complete circumferential attachment14to the sleeve13which is inverted into the distal sleeve chamber60. The external ring53is also attached to the proximal portion77of the inner member15via a first and second deployment tether94,95at attachment sites71on the introducer member12, usually 180° apart.

One example of how the embodiment ofFIG. 19is placed is that of a NG feeding tube59. The distal ends16,36of the outer and inner members12,15are placed into the opening of the nasal passage and the external ring53/introducer member12is typically urged in a proximal direction to cause the inner member15and NG feeding tube59into be introduced into the nasal passage. The sleeve13protects the lining of the nasal passage from trauma resulting from the advancing inner member15and NG feeding tube59as they advance toward the stomach. Deployment of the NG feeding tube59from the inner member occurs within the esophagus, once the distal end36of the inner member15has passed through the sensitive nasal passages. At this point, the tethered ring53is pulled backward until the NG tube59pushes through the aperture66in the chamber septum65, then into the distal sleeve chamber60, and out the distal end36of the inner member15. The external ring53and tethered sleeve13are pulled over the external surface of the indwelling NG feeding tube59where they are cut free, once outside the patient. To help ensure that the NG tube has sufficient column strength to penetrate chamber septum65, a stiffening stylet97can be introduced into the passageway98of the NG tube to improve its pushability, whereby it is removed once the NG tube59has been advanced through the distal end36of the inner member15.

More simplified embodiments of the universal introducer concept can be found inFIGS. 31-33. As depicted, the inner member15includes an longitudinal expansion zone103that allows the inner member15to radially expand, especially following removal of the introducer assembly11, to allow variously-sized devices of a larger diameter to be introduced therethrough. The embodiment ofFIG. 31includes an inner member15with longitudinal expansion zone103comprising an expansion pleat99. The expansion pleat99represents an invagination in the wall of an inner member15which is then folded over to create an inner member15of a first, unexpanded diameter as shown in the figure. The introducer member12(external ring53) acts as a containing mechanism to maintain the inner member15in the first diameter. When the introducer member12and sleeve13are removed from over the inner member15, it permits a third member or device59(like that shown inFIG. 19) to be introduced through the inner member, which then assumes a larger, second diameter. The expansion pleat99unfolds to allow passage of a device (e.g., an NG tube) that has a larger diameter than the first diameter of the inner member15, these advantageously providing the combination of a smaller introducer with a larger, optimally sized indwelling device.

FIG. 32depicts another embodiment of an expandable inner member15having a longitudinal opening74or split in which the longitudinal expansion zone103comprises an overlapping area100of the first edge101and the second edge102defined by the longitudinal opening74. In the illustrative embodiment, the first edge101is folded over the second edge102to create the overlapping area and give the inner member a first, unexpanded diameter that is maintained by the external ring53of the introducer member12. When the introducer member12and sleeve are removed, the second, inner edge102and first, outer edge are able to slide toward one another, thereby allowing radial expansion of the inner member15to the second, expanded diameter for passage of a larger diameter device. In a variation of this embodiment, depicted inFIG. 33, the first and second edge101,102of the cut tube can be attached via an expandable bridge104of a second and usually more flexible material. The expandable bridge104of the longitudinal expansion zone103can extend underneath the first edge101, forming an overlap100similar toFIG. 32, or the first and second edges101,102may not actually overlap. In the latter instance, expansion can result from folding or invaginating the flexible material of the expandable bridge104to permit radial expansion of the inner member15, or relying on elastic properties of the expandable bridge104to allow the inner member15to assume a second, expanded diameter when a larger diameter device is passed therethrough.

FIG. 36depicts an embodiment of a nasal introducer used to cannulate the nasal passages112to introduce a third member or device59, such as a nasal endoscope. Since the sleeve13does not need to be separately removed from the inner member15, which is only introduced a relatively short distance to provide a conduit for passage of the third member59, the second end64of the sleeve13is conveniently, but not essentially, affixed to the inner member15. Because the second member15functions as introducer, it is generally preferable that the attachment111of sleeve13to the second member15be located and configured such that the passageway22of the inner member15remains substantially unobstructed to facilitate passage of the third member59.FIG. 36shows one example of such an attachment111, which is affixed about the distal end36of the inner member15with the attachment111occurring within a groove114formed in the distal end36thereof, leaving the passageway22clear and unobstructed after the sleeve13has fully everted. It would still be within the scope and spirit of the invention for the attachment111to be located such that a portion of the sleeve remains within the passageway when the inner member15is fully extended, as long as the sleeve13is eversible to the point where the passageway22is not significantly or functionally narrowed or obstructed by the sleeve13and/or its attachment111. The term ‘eversible’ should therefore be understood to be equivalent to the concept of being ‘functionally eversible’, whereby, unlike the Bidwell '670 device with its internal ‘retention sled’ to which the sleeve is attached, the sleeve and attachment of the present invention have the capacity to clear the passageway22to a sufficient degree as not to interfere with the passage of a third member59therethrough. Features described in the other accompanying embodiments may also have particular utility for the embodiment ofFIG. 36, such as a channel93to prevent the introducer member12from rotating relative the inner member15(FIG. 16), and a preformed inner member15(FIG. 24) that facilitates navigation of the inner member15and/or third member59toward the nasopharynx113.

FIG. 35depicts an embodiment in which introducer member12and sleeve13can be introduced into the body without preloading the sleeve13into the inner member15. In the illustrative example, the second end64of the sleeve13is attached to a wire guide62that was been preloaded into the introducer member12. The sleeve13and wire guide62can be coupled such that the wire guide62can slide relative to the sleeve13or that the sleeve13is fixed over the wire guide62. A sleeve attachment108is used, such as a small band, suture, adhesive, or other means of gathering and securing the second end64of the sleeve, which allows the sleeve13to become detached from the wire guide62when the advancing inner member15pulls it loose, either by sliding off the attachment member108from around the sleeve13(such as onto the wire guide) or causing an opening or detachment of the attachment member108to release the sleeve13. By gathering and attaching the second end64of the sleeve13about the wire guide62, the second end64is readily drawn into the passageway22of the inner member15as it tracks over the wire guide62upon advancing toward the distal end16of the outer member12. While attachment of the second end64to the wire guide62facilitates capture of the sleeve13within the passageway22of the inner member15, it is also possible to eliminate the wire guide62, especially if not otherwise useful in the procedure, and gather the end64of the sleeve13by configuring the attachment mechanism108in such a manner that it facilitates capture by the advancing inner member15. In such an embodiment, adding stiffness to, and/or gathering up the sleeve over several millimeter or centimeters (such as using a plurality of attachment bands108) would improve the reliability of the sleeve13being effectively fed into the passageway22as the inner member15is advanced.

The eversible sleeve introducer11of the present invention can also be used to deliver stents61and other tubular prosthetic devices as depicted inFIGS. 20-21. In the embodiment ofFIG. 20, a stent61, such as a self-expanding intraluminal stent, is mounted over the inner member15and this assembly is loaded within the tubular introducer member12. The sleeve13is everted into the passageway22of the inner member15which functions as the delivery or pusher catheter. The inner member15includes a lip63that maintains a force against the proximal end of the stent61that assists in placement of the stent61at the desired location. The stent61is advanced out of the introducer member12as the sleeve13is everted and subsequently protects the lining of the bodily passage from the friction that would result from the advancing stent61. When the sleeve13has finished everting from the passageway, the stent61becomes exposed to the bodily passage into which it is to be placed. In the case of a self-expanding stent61, the sleeve13may also provide a restraint that helps prevent its full expansion. As the sleeve13passes over and exposes the advancing stent, the deploying stent61is able to expand against the walls of the bodily passage. In a related embodiment shown inFIG. 21, the loaded stent61is made of a lower profile because it is not delivered from within the introducer member12which otherwise adds to the outer diameter of the introducer apparatus10. In the illustrative embodiment, the distal end16of the introducer member12does not extend over any portion of the stent61which has been mounted over the inner member15. The inner member15of this embodiment also includes a lip63. Without the introducer member12extending over the stent61, the sleeve13provides the only restraint and protection to the stent as it is delivered. In this particular embodiment, the stent61is sized to include a space86between the inside of the stent61and the outer surface of the inner member15. The space86permits the inner member15to be readily withdrawn from within the passageway87of the stent61without catching thereon and possibly causing it to be dislodged from the target area of deployment. Alternatively, the stent could be mounted on a balloon and deployed in that manner once exposed by everted sleeve and/or introducer member.

FIG. 22depicts an embodiment in which a series of friction reduction means68are included about the distal tip29of an inner member15of an introducer apparatus10. In the illustrative embodiment, the friction reduction means68includes three ball bearings88or beads which a mounted in the distal face67of the distal tip29. The ball bearings88are rotatable within their mountings via friction applied by the sleeve13as it drags thereover, therefore allowing the sleeve13to move more freely. A similar concept is shown inFIG. 22Awherein a series of rollers89are mounted about the distal face, encircling the passageway22opening. In the illustrative embodiment, the hollow rollers89are threaded over a wire frame90which comprises two opposing semi-circular frame halves124,125. The adjacent first ends91of the two wire frame halves124,125are embedded into the distal face67at a point along passageway22opening and the seconds ends123are embedded into the distal face67approximately 180° from the first ends91along the passageway22opening, such that the wire frame90is circular with each frame half124,125holding approximately half of the rollers89. Optional supports122mounted on the distal face67support the wire frame90and provide spacers between the rollers89. Other means of reducing friction include providing a highly lubricious material to the distal face67(e.g., a highly polished metal tip annular ring), coating the end of the device with lubricious polymer coating such as SLIP-COAT® (Sterilization Technical Services, Rush, N.Y.), or changing the surface energy of the distal face67through other means such as ion beam bombardment.

While the embodiments of the preceding figures generally provide for a single passageway22through which materials or devices can be introduced to the target site, it possible to provide for one or more additional lumens in the introducer apparatus10separate from the passageway22that houses the eversible sleeve13. As depicted inFIG. 25, the inner member15includes a second passageway58for passage of a device, such as a wire guide62, or for injection of contrast media or other materials. In this embodiment, the sleeve13represents a partial sleeve43. The partial sleeve43allows the second passageway58to remain continually open and accessible at all times, while still providing a degree of friction reduction between a portion of the inner member15and the bodily passage.FIGS. 26-27show embodiments in which the introducer member12includes a second passageway72. In the embodiment ofFIG. 26, the sleeve13and the attachment means14to the introducer member12are similar to single passageway embodiments such as that ofFIG. 1. The second passageway72, located proximal to the sleeve attachment14, is especially useful as an injection port, but can also function to receive a wire guide, if appropriately sized. A second multi-lumen introducer member12is depicted inFIG. 27wherein the distal end16of the introducer member is more truncate than that ofFIG. 26and the sleeve attachment14comprises an annular or ring structure mounted on the distal end16with the opening to the second passageway72being positioned on the face of the distal end16adjacent to the sleeve13and attachment14. The attachment14can either be a plastic or metal ring to secure the sleeve13to the introducer member12, or a ring of adhesive. As mentioned, the embodiment ofFIG. 27also includes a longitudinal opening74to allow the introducer member12to be removed from over the inner member15with the sleeve13and attachment14made splittable or detachable as well to allow removal over the inner member15. Obviously, it is possible to have additional passageways beyond the second passageway58,72depicted inFIGS. 25-27. For example the second passageway58,72might be used for introduction of wire guides or medical devices while the third passageway is used for injecting contrast media.

FIGS. 28-30depict an example of a method of using a selected embodiment of the present invention to cannulate a stricture within a bodily passage. As depicted inFIG. 28, the distal end16of the introducer member12is placed against the opening27to the bodily passage26where the introducer member12is then pulled back relative the inner member15which is initially restrained. This allows the inner member15to grip the opening and -advance into bodily passage26as the sleeve13is laid down when everting from the inner member15. InFIG. 29, the inner member15has passed through the stricture and the sleeve13has now completely everted from the passageway22of the inner member. The inner member15is maintained at the target site, while the introducer assembly11is removed from the patient by one of several mean discussed above. InFIG. 30, only the inner member15remains from the original introducer apparatus10. It can serve as an introducer for a wire guide62or other medical treatment device and may be itself removed from the patient once access across the stricture is gained, leaving the wire guide and/or other device(s) in place. It should be noted that unlike procedures such as nasal, colonic, and urethral access where it is advantageous or desired to improve patient comfort during both ingress and egress of the introducer apparatus10, it may be less important in other medical procedures, such as cannulation of certain internal sphincters and strictures, to maintain the sleeve13in place during removal of the inner member15, the critical function of the sleeve13having been already fulfilled.

Any other undisclosed or incidental details of the construction or composition of the various elements of the disclosed embodiment of the present invention are not believed to be critical to the achievement of the advantages of the present invention, so long as the elements possess the attributes needed for them to perform as disclosed. The selection of these and other details of construction are believed to be well within the ability of one of even rudimentary skills in this area, in view of the present disclosure. Illustrative embodiments of the present invention have been described in considerable detail for the purpose of disclosing a practical, operative structure whereby the invention may be practiced advantageously. The designs described herein are intended to be exemplary only. The novel characteristics of the invention may be incorporated in other structural forms without departing from the spirit and scope of the invention.