Abstract:
An apparatus and method for inserting an article into a body opening. A radially expandable introducer sheath is delivered in a non-expanded condition into a body opening. A release mechanism releases the introducer sheath from the non-expanded condition into a condition that permits radial expansion of the introducer sheath upon introduction of a medical device through the sheath into the body opening. An optional handle having a circumferential opening may be provided for withdrawing the sheath from the body opening, while leaving the medical device in place.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to an introducer sheath, and to a method for inserting an article into a body opening of a patient through the introducer sheath.  
           [0002]    The insertion of medical instruments through a pre-dilated hole in a patient&#39;s body is often accomplished in relatively straightforward fashion. An axial force is exerted on the instrument, thereby forcing the instrument through the opening into the desired internal part of the body. In certain medical procedures, however, medical professionals may encounter difficulties when inserting an instrument through a pre-dilated hole. In these instances, the axial force causes an undesired axial extension of the opening and increases the trauma experienced by the patient at the site. This axial extension can be particularly problematic in certain medical procedures, such as a tracheostomy, where a dilator is advanced into the trachea through the pre-dilated hole to open the trachea for introduction of a tracheostomy tube. In this instance, the axial force exerted by the dilator may cause the trachea to collapse, thereby further increasing the trauma to the patient and preventing the establishment of proper ventilation. In order to minimize the possibility of a tracheal collapse, the physician must repeatedly insert and withdraw one or more dilators at incrementally greater distances and/or incrementally greater diameters until the desired dilated diameter is obtained. This process can be very time-consuming at the very time that prompt action may be critical to the patient&#39;s well-being.  
           [0003]    Some manufacturers have attempted to minimize this problem by providing dilators having a hydrophilic external surface to reduce the amount of friction encountered upon dilation, and thereby reducing the amount of axial force that is exerted on the trachea. Although the use of such coated dilators is somewhat effective in reducing the amount of friction encountered during dilation, there remains a desire to even further reduce the forces exerted on the body opening during dilation, thereby further minimizing the trauma to the patient.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention addresses the needs of the prior art by providing a method and apparatus for inserting an article into a body opening of a patient.  
           [0005]    In one form thereof, the invention comprises a method for inserting an article into a body opening. The body opening is dilated, and a radially expandable introducer sheath is inserted into the dilated body opening. The article is inserted through the expandable introducer sheath, thereby radially enlarging the body opening. The introducer sheath is then withdrawn, while leaving the article in place in the body opening.  
           [0006]    In another form thereof, the invention comprises a method for percutaneously inserting an article in a body opening. A wire guide is inserted into the body opening, and the opening is dilated by inserting a dilator mechanism over the wire guide. The dilator mechanism includes an outer cannula that has a lumen therethrough, and a dilator positioned within the lumen. The dilator is then withdrawn, while the outer cannula is left in the body opening. A radially expandable introducer sheath is delivered over the wire guide into the lumen of the outer cannula. The introducer sheath is delivered in a non-expanded condition, and includes a release mechanism for releasing the introducer sheath from the non-expanded condition. The outer cannula is then removed, leaving the introducer sheath in the body opening. The release mechanism is activated to permit radial expansion of the introducer sheath, and the article is inserted through the expandable introducer sheath, thereby radially expanding the sheath.  
           [0007]    In still another form thereof, the invention comprises a radially expandable introducer sheath for enlarging a percutaneous opening. The radially expandable sheath comprises a sheath body that comprises a folded distal portion when the sheath is in a non-expanded condition and an extended distal portion when the sheath is in a radially expanded condition. The sheath also comprises an insertion member for holding the sheath body in the non-expanded condition.  
           [0008]    In yet another form thereof, the invention comprises a radially expandable introducer sheath for use in the percutaneous insertion of an article in a body opening. The introducer sheath comprises a sheath body that can be aligned to provide an axial opening for passage of the article therethrough into the body opening. A handle is engaged with the sheath body. The handle comprises an axial opening that is aligned with the sheath body axial opening, and further comprises a perimetrical opening through which the sheath may be withdrawn from the inserted article in the body opening.  
           [0009]    In another form thereof, the invention comprises an introducer sheath system for use in the percutaneous insertion of an article in a body opening. The introducer sheath system comprises an introducer sheath comprising a sheath body and an insertion cannula. A distal end of the sheath body is foldable within an inner lumen of the insertion cannula when the sheath is in a non-expanded condition, and extendable beyond said insertion cannula to permit radial expansion of said sheath. The introducer sheath optionally includes a handle. When present, the handle may have either a continuous circumference, or an opening along the circumference of the handle through which the sheath may be withdrawn from the article in the body opening. The introducer sheath system further comprises a dilator for dilating the body opening. The dilator optionally includes a peel-away sheath member that provides a passageway for the introducer sheath into the body opening. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a side view of a prior art process for dilating a body opening.  
         [0011]    [0011]FIG. 2 is a side view of a process for dilating a body opening illustrating the use of an introducer sheath of the present invention.  
         [0012]    [0012]FIG. 3 is a side view of a preferred embodiment of an introducer sheath, illustrating a handle and a sheath body in a non-expanded condition.  
         [0013]    [0013]FIG. 4 is a top view of the introducer sheath of FIG. 3.  
         [0014]    [0014]FIG. 5 is a perspective view of a handle showing the presence of rings for retaining the sheath body, and a pusher mechanism for inserting a wrapped sheath.  
         [0015]    [0015]FIG. 6 is a perspective view of a continuous handle for an introducer sheath, showing the handle in the open position.  
         [0016]    [0016]FIG. 7 is a perspective view of the handle of FIG. 6 in the closed position.  
         [0017]    [0017]FIG. 8 shows an embodiment of an introducer sheath including a splittable hemostatic valve.  
         [0018]    [0018]FIG. 9 shows a dilator/peel-away sheath arrangement for delivering the introducer sheath into the body opening.  
         [0019]    [0019]FIG. 10 illustrates an introducer sheath being delivered into the body opening over a wire guide.  
         [0020]    [0020]FIG. 11 is a perspective view of an introducer sheath in a non-expanded condition with a release mechansim.  
         [0021]    [0021]FIG. 12 is a sectional view taken along line  12 - 12  of FIG. 11.  
         [0022]    [0022]FIG. 13 is a perspective view of another embodiment of an introducer sheath in a non-expanded condition.  
         [0023]    [0023]FIG. 14 is a sectional view taken along line  14 - 14  of FIG. 13.  
         [0024]    [0024]FIG. 15 is a perspective view of another alternative embodiment of a sheath body.  
         [0025]    [0025]FIG. 16 is a side view of the embodiment of FIG. 15. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    [0026]FIG. 1 is a diagram illustrating the forces that are applied when a dilator  100  is used in the conventional fashion for dilating a body opening  102  of a patient. As shown in the figure, when dilator  100  is axially directed toward the body opening in the conventional manner, an axial force (F/2) is exerted on the body being dilated, and an equal but opposite force (F/2) is exerted on the dilator. The axial force exerted on the body opening results in the axial deformation of that opening in the direction of movement of the dilator, which deformation may cause discomfort and associated trauma to the patient. When certain body openings are being dilated, such as the trachea, the deformation may result in the collapse of that opening.  
         [0027]    [0027]FIG. 2 illustrates a view of a dilator and a body opening similar to that shown in FIG. 1. In this case, a radially expandable introducer sheath  10  is positioned between the dilator and the body opening. As used herein, the term “radially expandable” is used to refer to a sheath wherein the sheath body is capable of either expansion or displacement in the radial direction. The sheath body need not be formed of a material capable of expansion, as long as the material is capable of being displaced in a radial direction in response to a radially-directed force.  
         [0028]    In the embodiment of FIG. 2, introducer sheath  10  comprises a sheath body  12  and a handle  14 . As illustrated in FIG. 2, the use of the radially expandable introducer sheath in combination with the dilator  100  allows the body opening being dilated to be subjected primarily to radial forces (R), rather than axial forces as indicated in the conventional dilation shown in FIG. 1. The exertion of radial forces (R) on the body opening prevents substantial axial deformation of the body in the direction of the dilator, and thereby minimizes the potential adverse effects associated with such axial forces. Although FIG. 2 illustrates the use of introducer sheath  10  for insertion of dilator  100  into the body opening, other medical devices, such as a tracheostomy tube, may also be inserted into a body opening through sheath  10  instead of a dilator.  
         [0029]    The introducer sheath  10  of the present invention is preferably formed from a sheath body  12  comprising a low friction non-rigid or semi-rigid material, such as a low friction fabric or polymeric material. The lack of rigidity enables the configuration of the sheath material to radially expand from a generally collapsed state prior to insertion of the medical device to an expanded shape during insertion of the device. Non-limiting examples of suitable material for the sheath body include polymers such as expanded polytetrafluoroethylene, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE) and synthetic polyamides such as nylon. To increase lubricity, the sheath body can also be coated with a hydrophilic coating, such as SLIP-COAT®, available from STS Biopolymers Inc.  
         [0030]    The specific configuration of the introducer sheath is not critical, as long as it is capable of radial expansion in some manner from a non-expanded condition to a radially expanded condition when the medical device, such as a dilator or tracheostomy tube, is passed therethrough. Numerous designs are capable of such radial expansion and are considered within the scope of the invention. For example, the sheath body can be formed from an elastic or semi-elastic material that elastically expands to allow passage of the device, and thereafter reverts to a smaller size. Alternatively, the sheath in its non-expanded condition can have lateral folds in the nature of an uninflated balloon, or can have pleats, strips or other configurations that are capable of full or partial displacement in the radial direction in response to a radially-directed force.  
         [0031]    [0031]FIG. 3 illustrates a side view and FIG. 4 illustrates a top view of an embodiment of introducer sheath according to the present invention. In this embodiment, introducer sheath  10  includes sheath body  12  and handle  14 . The proximal end of sheath body  12  has a large diameter for attachment to handle  14 , while the distal end of sheath body  12  is wrapped in a manner such that it has a non-expanded, small diameter condition. Although these figures show that the small diameter configuration is formed by wrapping the distal end of the sheath body into this configuration, the invention is not so limited. Rather, any sheath body material that is capable of assuming a smaller diameter at its distal end and thereafter radially expanding to a larger diameter upon introduction of a medical instrument is within the scope of the invention.  
         [0032]    [0032]FIG. 5 is a perspective view of one type of handle that can be used with the sheath of FIGS. 3 and 4. Handle  14  includes supports  16  to support the fingers and/or thumb of the physician during use of the introducer sheath. Supports  16  provide enhanced control of the device and allow for ease of handling. In this embodiment, handle  14  includes one or more rings  18 ,  19  that may optionally be used to anchor the sheath in the handle. In the embodiment of FIG. 5, the upper portion of a sheath body can be wrapped around or otherwise secured to bottom ring  18 . Bottom ring  18  is then fitted into the interior of handle  14 , such as by resting on ledge  21 . Upper ring  19  is then inserted to seal lower ring  18  and the wrapped portion of sheath body  12  in the device by means such as gluing or ultrasonic connection. Any convenient attachment mechanism may be used in place of ledge  21 , such as one or more grooves along the inside surface of handle  14  into which the rings can be snapped for secure attachment. The handle shown has a generally C or U-shaped configuration. This configuration provides an open portion  20  along the handle circumference to allow easy removal of the introducer sheath once the medical device has been inserted into the body of the patient.  
         [0033]    Preferably, sheath body  12  includes a weakened portion such as an axial slit  23  extending along the length of the sheath to facilitate removal of the sheath after insertion of the medical device by tearing along the axial slit. (FIG. 8.) When the handle is configured having an open portion  20  such as that shown, sheath  10  may be withdrawn from the body opening by simply laterally pulling the sheath to the side and tearing the sheath via the axial split. To facilitate tearing of the sheath at the axial split, the sheath can also be provided with a small knick  22 . Knick  22  is useful to easily initiate the tear. After the sheath body is torn along the axial slit, the sheath may be removed, leaving the medical device in place in the body opening. Although the handle shown in FIGS.  3 - 5  is considered to have a generally “C” or “U” shape, this configuration is not critical. Other handle configurations that provide a perimetrical opening along the outer border, or perimeter, of the handle to facilitate removal of the sheath can likewise be used.  
         [0034]    Although the embodiment shown in FIGS.  3 - 5  includes a perimetrical opening  20  in handle  14 , it is not essential that the handle have an opening. Rather, the handle can be formed having a continuous geometric outer shape, such as a circular or rectangular shape. A continuous handle may be preferred when additional structural strength is desired in a handle.  
         [0035]    [0035]FIGS. 6 and 7 show an embodiment of a handle for an introducer sheath having a continuous handle. In the embodiment shown, handle  74  includes a pivot portion  24 , such as a hinge, on one side and a complementary snap portion generally opposite the pivot portion. Any conventional arrangement for snapping, or closing, an opening may be utilized, such as the tab  26 /receptacle  28  arrangement shown. The handle is shown in the open position in FIG. 6, and in the closed position in FIG. 7. The use of a closeable handle combines the benefits of a handle having a perimetrical opening for convenient removal of the medical device from the sheath with the strength of a continuous, closed handle. The hinge/tab combination enables the handle to be selectively “unsnapped” and pivoted open after the medical device has been inserted through the introducer. Any convenient attachment mechanism can be provided for attaching the proximal end of the sheath body to the handle. A sealing mechanism such as ledge  30  is provided. Ledge  30  may be used in conjunction with rings (not shown) around which the proximal end of sheath body  12  can be wrapped. Although the continuous handle shown in the figures includes structure enabling the handle to be selectively opened and closed, this feature is optional, and the continuous handle need not include this additional structure.  
         [0036]    The composition of the handle is not critical. Generally, the handle can be formed from any rigid or semi-rigid material having sufficient structural strength for the purposes described. One example of such a material is a high-strength plastic. In addition, metals such as aluminum, stainless steel or metal alloys can be used, along with composite materials. The handle may be molded or machined such that the ledges, tabs or other attachment structure can be pressed into the component.  
         [0037]    [0037]FIG. 8 shows a variation of an introducer sheath having a continuous handle, such as handle  74  in FIGS. 6 and 7. In this embodiment, the sheath includes a hemostatic valve member  32  having a slit, or valve,  34 , for preventing leakage of body fluids through the introducer sheath. Hemostatic valves are well-known in the art, and can be formed of, for example, silicone and polyisoprene. This sheath can be removed following insertion of the medical device in the same manner as the sheath of FIGS. 6 and 7. Preferably, this valve also includes a knick  22  or like feature adjacent the snap mechanism that allows the valve to peel away along an axial slit  23  as the handle is opened.  
         [0038]    Delivery Mechanism for Introducer Sheath.  
         [0039]    Another aspect of the present invention comprises a mechanism for delivering the introducer sheath into the body opening. One embodiment of such a delivery mechanism is shown in FIG. 9.  
         [0040]    Prior to dilating a body opening, the initial opening through the skin is normally made with a needle. A wire guide  60  is then inserted into the body opening over, or through, the needle. Following insertion of the wire guide, the needle is withdrawn and a dilator is advanced over the wire guide to dilate the initial opening in well-known fashion. A dilator/sheath combination  50  may be used for the dilation. Dilator/sheath combinations are known, and include a dilator  52  pre-loaded into a sheath  54 . For convenience, it is preferred that the sheath is a peel-away sheath. In a preferred embodiment, the distal end portion of the dilator provides a smooth, or substantially smooth, transition to the distal end of the peel-away sheath so that the dilator/peel-away combination can be readily inserted, or punched, through the skin  56 .  
         [0041]    After the opening has been dilated by punching dilator/sheath combination  50  through the skin, dilator  52  is withdrawn by sliding it over the wire guide  60 . Introducer sheath  10  is then inserted through the lumen of the peel-away sheath in the direction of the arrow shown in FIG. 10. Peel-away sheath  54  is removed by peeling away petals  58  in well-known fashion, leaving radially expandable introducer sheath  10  in place in the body opening. Although it is preferred that a wire guide be used to guide the entry of the expandable sheath and other medical devices into the body opening, the use of a wire guide is not critical to the use of the inventive introducer sheath and the sheath may be utilized in the absence of a wire guide.  
         [0042]    Release Mechanism for Introducer Sheath.  
         [0043]    During delivery of the introducer sheath into the body opening, the sheath is retained in its non-expanded state so that it can be easily passed through the inner lumen of peel-away sheath  54 . In the embodiment of FIGS. 11 and 12, the non-expanded state is achieved by wrapping the distal portion of the sheath into a smaller diameter configuration. Also, in this embodiment, the distal-most end  13  of sheath body  12  is folded in an inward direction, thus “sandwiching” this distal end between wire guide  60  and an insertion cannula  64 . (FIG. 12) The introducer sheath is also provided with a pusher mechanism  66  and a cap  68 , as shown in FIGS. 5, 11 and  13 . Pusher mechanism  66  extends from proximally outside of cap  68  to the inwardly-wrapped distal portion  13  of sheath body  12  at the distal end of introducer  10 . To release the distal portion of the sheath from the closed position shown in FIG. 11, pusher mechanism  68  is advanced by depressing knob  67 . Pusher mechanism  68  forces distal end  13  of sheath body  12  out the distal end of insertion cannula  64 , thereby releasing the sheath and permitting it to expand radially and thereby dilate the body opening when a device is axially inserted therethrough.  
         [0044]    Insertion cannula  64  can be engaged with cap  68  in a manner such that insertion cannula  64 , pusher mechanism  66  and cap  68  are releasable as a unit following release of the sheath. This can be accomplished, among others, by providing handle  14  and cap  68  with complementary screw threads, such that cap  68  can simply be unscrewed from handle  14 , and the entire assembly comprising cannula  64 , pusher mechanism  66 , and cap  68  mechanism can be removed as a unit. Cap  68  in the embodiment of FIG. 5 includes optional tabs  69  to assist in unscrewing the cap. In an alternative embodiment, the pusher mechanism can be eliminated and/or it can be integral with the inner cannula. In this instance, the inner cannula can be structured such that it releases the distal end of the sheath material as it is advanced forwardly through the sheath. The insertion cannula, pusher and cap may be formed from any compatible rigid, or semi-rigid material having sufficient structural integrity to maintain its shape during use.  
         [0045]    In yet another embodiment, a dilator may be combined with the release mechanism. This embodiment is shown in FIGS. 13 and 14. Distal end  13  of sheath body  12  is held in place by sandwiching the material between wire guide  60  and insertion cannula  64 , as described in the previous embodiment. In this embodiment, pusher mechanism  66  is engaged with a dilator tip  70  that extends through the distal end of introducer sheath  10 . Preferably, dilator tip  70  is integral with pusher mechanism  66 . This combined dilator/release mechanism can be inserted into the body opening directly over the wire guide, without the necessity of pre-dilation. After the device is inserted into the body opening, the pusher and dilator are advanced forwardly as described in the previous embodiment to release and radially expand the sheath material. The insertion cannula and the dilator/release mechanism can then be withdrawn through the expanded sheath.  
         [0046]    Although the examples shown above illustrate the presence of a handle  14  on the introducer sheath body, a handle is not necessary in all embodiments to achieve the radial expansion of the sheath. One embodiment of a sheath not having a handle is shown in FIGS. 15 and 16. In this embodiment, the sheath material  12  is rolled in a clock-spring configuration, which can then be inserted into the body opening. The dilator can then be axially inserted into the rolled-up sheath. As the dilator is advanced in the sheath, the sheath body unwraps in the radial direction to exert the radial force on the body opening. Other configurations permitting radial expansion of the body opening in the manner described may be substituted for those specifically described, and are considered within the scope of the invention.  
         [0047]    Those skilled in the art will appreciate that the inventive concept is not limited to use in tracheostomy procedures, and that the device could be used anywhere in the body where a dilated hole is needed. Although in most instances it is believed that the inventive device will be used in external dilated body opening, the device can also be used in an internal hole, such as a stricture in a biliary tree, and the like.  
         [0048]    While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. Those skilled in the art may recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein, which equivalents are intended to be encompassed in the scope of the invention.