Abstract:
A surgical sheath for use in endoscopic trans-nasal or intra-ocular surgery is made of a braid material. The sheath may be manufactured by placing a length of braided tube material over a mandrel. The braid material is conformed to the shape of the mandrel and is then heat set. An atraumatic end may be made by folding or rolling one or both ends of the sheath. A coating may also optionally be applied to the braid material. The sheath reduces collateral trauma to the tissues in the surgical pathway.

Description:
[0001]    This application is a continuation-in-Part of U.S. patent application Ser. No. 15/340,718 filed Nov. 1, 2016 and now pending, which is a continuation of U.S. patent application Ser. No. 14/626,184 filed Feb. 19, 2015 and now abandoned, which is a continuation of U.S. patent application Ser. No. 13/798,990 filed Mar. 13, 2013, now U.S. Pat. No. 8,986,201. This application also claims priority to U.S. Provisional Patent Application No. 62/396,746 filed Sep. 19, 2016 and now pending and U.S. Provisional Patent Application No. 62/377,400 filed Aug. 19, 2016 and now pending. Each of the applications listed above is incorporated herein by reference 
     
    
     BACKGROUND 
       [0002]    Endoscopic surgery within the head is a common procedure in neurological surgery and otolaryngology. It avoids large cranial incisions and can reduce the need brain retraction and prolonged wound healing. Endoscopic surgery within the head also provides improved illumination and visualization of the target tissues because the camera of the endoscope is brought directly to the surgical site. 
         [0003]    During this type of surgery, there may be local trauma to the tissues in the surgical pathway, resulting from pressure or abrasion caused by the surgical tools. Generally these tissues are the nasal mucosa, turbinates, nasal septum, and sphenoid/frontal/maxillary sinus. When transorbital approaches are used, orbital and periorbital tissue are subject to local trauma. Surgical pathway trauma can add to the trauma of the procedure and prolong the patient&#39;s recovery time. Liquids in the surgical pathway, such as mucous, blood, and soiled irrigation fluid, tend to obscure the view of the endoscope. This leads to the constant need for irrigation and suction of the obstructing liquids. In some cases the endoscope may also have to be removed, cleaned and replaced multiple times during a single procedure. This disadvantage tends to increase the complexity and time requirements of the operation. In addition, with each movement of a surgical tool into or out of the surgical pathway, the surrounding tissues are put at risk of additional trauma. Improved devices and methods are therefore needed. 
       SUMMARY OF THE INVENTION 
       [0004]    An access sheath is provided to protect the nasal passageway during endoscopic trans nasal or intra ocular surgery. The access sheath protects the entrance of the nares and sinus from the placement and manipulation of surgical tools both during the initial placement and during manipulation and exchange of surgical tools. The access sheath may provide a guide port to help direct surgical tools into position. In some designs the access sheath may splint the sinus open, to help open and provide access past the turbinate. The access sheath may also help to keep surgical tools and especially an endoscope freer from obscuring matter and secretions 
         [0005]    The access sheath may be flexible for placement in a folded or rolled up configuration, have a hoop or expansion capability to fill and splint the passage, be partially or totally fluid tight to reduce ingress of secretions, and be lubricious for the unobstructed motion of fine surgical tools during delicate micro surgery. 
         [0006]    U.S. Pat. No. 8,986,201 B2 discloses an access sheath, which may be made of elastomer, and has many of the performance features described above. However, elastomer has an inherent draw back. Flexible elastomers are inherently tacky and hence create sliding friction on surgical tools. In some designs this has required additives or a coating on the surface of access sheath to reduce friction. Still generally additives and coatings cannot always provide the surgeon with the feel of a surgical tool sliding against a wet mucus layer. 
         [0007]    A nasal access sheath made of a hard plastic material is manufactured in a way to make it flexible, in one embodiment, by using a braided tube. A braid can be made from multiple fibers of plastic monofilament. Monofilaments can be made of rigid and tough plastic such as PET (Polyethylene terephthalate) or Nylon. Monofilaments can even be made from stainless steel. The fibers remain flexible because they have a small diameter, such as 0.08 mm to 0.5 mm. The fibers may have a round cross section, a relatively flat cross section, or elliptical cross section, A plurality of fibers can be braided into a braided tube. As one example, 64 fibers are counter wound in a two over and two under braid. The angle (pics or pitch) of the braided fibers can select the circular profile of the resulting braided tube or sleeve. A braided tube additionally is flexible due to the loose association of the braided fibers and their ability to slide relative to each other but still maintain the intended braided pattern. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    In the drawings, the same reference number indicates the same element in each of the views. 
           [0009]      FIG. 1  shows a braided tube. 
           [0010]      FIG. 2  shows a braided tube expanded and loaded over a cylindrical mandrel. 
           [0011]      FIG. 3A  shows a forming mandrel shaped with a preferred geometry for use in the human sinus. 
           [0012]      FIG. 3B  shows a braided tube expanded and loaded over the forming mandrel of  FIG. 3A . 
           [0013]      FIG. 4  shows a braided tube that has been heat formed and the mandrel of  FIG. 3A  removed. 
           [0014]      FIG. 5  shows a heat formed braided tube that has been coated with an elastomer. 
           [0015]      FIG. 6  shows a heat formed braided tube with the braid inverted to form a dual layer, and with the distal end folded back on itself to provide a rounded tip. 
           [0016]      FIG. 7A  shows a braided tube created by a single layer of braid formed with a continuation distally of unformed braid. The formed portion was then dipped in a coating of elastomer. 
           [0017]      FIG. 7B  show the structure of  7 A, where the uncoated distal extension of braid has been inverted back through the formed and coated section. 
           [0018]      FIG. 7C  shows the structure of  FIG. 7A  where the uncoated distal extension of braid was then inverted resulting in a braided tube having a rounded distal end and an un-coated inner surface and a coated outer section. 
           [0019]      FIG. 8A  shows the distal end or edge of a single layer braided tube. 
           [0020]      FIG. 8B  shows the distal end of a two layer braided tube with an inverted distal end. 
           [0021]      FIG. 9A  shows the coated braided tube of  FIG. 7C or 8B  with two surgical tools placed in parallel. 
           [0022]      FIG. 9B  shows the coated braided tube with two surgical tools at an acute angle and the flexible response of the neck of the structure. 
           [0023]      FIG. 10A  shows the coated braided tube next two an introduction tool that has a longitudinal release slot. 
           [0024]      FIG. 10B  shows the coated braided tube loaded into the introduction tool of  FIG. 10A . 
           [0025]      FIG. 10C  shows the loaded introduction tool being inserted into the nose. 
           [0026]      FIG. 10D  shows the introduction tool fully inserted into the nose. 
           [0027]      FIG. 10E  shows the coated braided tube being mostly released out of the longitudinal release slot of the introduction tool. 
           [0028]      FIG. 10F  shows the coated braided tube fully released out of the longitudinal release slot. 
           [0029]      FIG. 11A  shows the access sheath and a plunger deployment tool. 
           [0030]      FIG. 11B  shows the access sheath loaded in the plunger deployment tool. 
           [0031]      FIG. 11C  shows the access sheath expelled distally from the plunger deployment tool. 
           [0032]      FIG. 12A  shows a beam and groove scissor-like delivery tool in an open position. 
           [0033]      FIG. 12B  shows the delivery tool of  FIG. 12A  in a closed position. 
           [0034]      FIG. 12C  is a top view of the access sheath of  FIG. 5, 8A or 9  loaded onto the delivery tool. 
           [0035]      FIG. 12D  is a side view of the access sheath and delivery tool shown in  FIG. 12C . 
           [0036]      FIG. 13A  is a side view of an embodiment of an elastomeric access sheath having a rigid plastic internal collar to create a low friction surface. 
           [0037]      FIG. 13B  is a front end view of the access sheath shown in  FIG. 13A . 
           [0038]      FIG. 13C  shows a rigid collar for installment in an access sheath, with the rigid collar having radial slots to allow the rigid collar to flex. 
           [0039]      FIG. 13D  shows the rigid collar of  FIG. 13C  installed in an access sheath. 
           [0040]      FIG. 13E  is a side view of the rigid collar shown in  FIG. 13C . 
           [0041]      FIG. 13F  is a side view of an embodiment of an elastomeric access sheath having the rigid plastic internal collar shown in  FIG. 13C . 
           [0042]      FIG. 14  shows the access sheath with an external rim of elastomer to create an atraumatic tip. 
           [0043]      FIG. 15  is a side view of the access sheath of  FIGS. 3-9B  with preferred dimensions and angles. 
           [0044]    FIG. 16  is a bottom view of the sheath shown in  FIG. 15 . 
           [0045]      FIG. 17  is a section view of the sheath shown in  FIG. 15 . 
           [0046]      FIG. 18  is left end view of the sheath of  FIG. 15 . 
           [0047]      FIG. 19  is a right end view of the sheath of  FIG. 15 . 
           [0048]      FIG. 20  is an enlarged detail view of detail A shown in  FIG. 18 . 
           [0049]      FIG. 21  is front, top and right side perspective view of the sheath shown in  FIG. 15 . 
           [0050]      FIG. 22  is rear, bottom and right side perspective view of the sheath shown in  FIG. 15   
       
    
    
     DETAILED DESCRIPTION 
       [0051]      FIG. 1  shows a braided tube  20  in its natural braided state. In  FIG. 2  the braid is shown on a cylindrical mandrel  22  to demonstrate its tubular shape and ability to expand. The braided tube  20  can be drawn down to a smaller diameter by stretching and pulling the monofilaments into a more longitudinal alignment. Conversely, the braided tube  20  can be expanded to a larger diameter by compression and pushing the filaments into a more radial directed alignment. 
         [0052]    The braided tube  20 , especially if made of plastic, can be placed around a mandrel  22  that causes the braided tube  20  to expand to a specific diameter or shape. The braided tube  20  can then be heat set in an oven. Upon cooling the braided tube  20  will be permanently formed into the shape of the mandrel  22 . Heat setting mandrels can be made of hollow or solid stainless steel, Delrin (acetal homopolymer resin). Mandrels  22  may be made of Teflon (fluoropolymer), especially if intended to coat the braided tube in a plastic/rubber/silicone dispersion. Heat setting can be done at a variety of temperatures and time, depending on the braided tube material and the heat capacity of the mandrel  22 . A useful heat set temperature for nylon or PET braids is 120° C. and 150 ° C. for half an hour, followed by cooling to room temperature in ambient conditions or a quench in water. 
         [0053]      FIG. 2  shows braided tube  20  loaded over a Delrin® forming mandrel  22  prior to heat setting. The mandrel  22  may be sized and shaped to product an access sheath having the shape and dimensions discussed in U.S. Pat. No. 8,986,201, incorporated herein by reference, and as shown in  FIGS. 15-22 . 
         [0054]      FIG. 3A  shows a forming mandrel  22  in a preferred geometry for manufacturing an access sheath  40 .  FIG. 3B  shows a braided tube  20  placed over and around the mandrel  22 . After the braided tube  20  is loaded over the forming mandrel  22 , the braided tube  20  may be conformed to the shape of the mandrel  22  by a partial or complete wrapping of self-adhering silicone tape over the braided tube  20 , or alternatively via a shaping block pressed onto the braided tube  20  on the mandrel  22 , with the shaping block having an internal opening complimentary to the mandrel, but sized to account for the thickness of the braided tube  20 . 
         [0055]      FIG. 4  shows the braided tube  20  after it has been heat formed, removed from the mandrel  22  and trimmed at both distal and proximal ends. This results in a highly flexible, thin, and simple to manufacture access sheath  40 . This sheath  40  is permeable which allows natural mucus lubrication of the sinus to enter into the access sheath for additional lubricity. The braiding pattern may be modified to allow more or less permeability by changing the diameter of fibers or filaments of the braid material. Flat monofilament or multi-filar fibers may be used to increase the PIC (how tight the braiding is formed), and reduce the interstitial spacing between fibers of the braided tube  20 . 
         [0056]    The braided tube  20  may be coated with a semipermeable or more preferably an impermeable membrane. A less tacky coating or a harder urethane material, of durometer 50 A or harder, may be used. It can be applied in thicknesses of 0.1 mm to 0.3 mm. Due to the thinness and the flexibility of the braided tube, even when coated the braided tube may still remain flexible, foldable, and be able to elongate. 
         [0057]    In an alternate embodiment a PET (Polyethylene Terephthalate) braided tube can be used with a uniform coat of a silicone dispersion (Nusil MED16-6606). Despite being silicone this combination provides a slick surface relative to surgical tools. This can be attributed to the mechanical nature of the structure. The braid surface provides a non-continuous, undulating surface where a full surface contact is replaced by a series of discrete contact points. Discrete contact points reduce the surface area of contact and hence reduce the friction between access sheath  40  and the surgical tool. 
         [0058]    A single layer braided tube coated in an impermeable silicone, such as NUSIL silicone dispersion 6061, was found to be a good coating as it applies in a thin layer and despite being silicone (that has inherent tackiness) has little tack. The resulting friction as tested showed 50 grams of friction. This is about the same friction as hydrophilic coated devices when tested new. The lubricious nature of the material also does not degrade over time, unlike hydrophilic coatings. 
         [0059]    Examples of lubricious coatings are: ceramic coatings. Slick-Sil coating (by Surface Solutions Group), Parylene coating, and hydrophilic coatings. Similar coatings can provide better friction reduction but may not feel as lubricious as mucous membrane. 
         [0060]    Hydrophilic coating provide lubricity similar to mucous membranes, however they require wetting with water or saline to activate, and need periodic or continuous re-wetting to stay slick. Hydrophilic coatings also wear away after multiple abrasions with surgical tools and may not withstand the long procedure time of skull base neurosurgery. Examples of lubricious additives are: barium sulfate, powdered Teflon (fluoropolymer) glass fillers, and ceramic fillers. These can reduce the surface tack but also tend to provide a surgical tool feel that is different from mucous membranes. 
         [0061]    The elastomeric coating on the internal surface of the braided tube  20  may be reduced. If the mandrel  22  is created from a semi flexible rubber or jacketed in rubber it results in a flexible surface. If the braided tube  20  is loaded over this surface and stretched to tightly engage the mandrel  22 , the internal contact points of the braided tube embed slightly into the semi-flexible mandrel surface. This effectively masks the internal surface of the braid. A coating step fully coats the external braided tube while leaving the highest contact points of the internal braided tube uncoated and fully retaining the inherent lubricity of the hard plastic monofilament of the braided tube. A semi flexible surface may also be achieved by jacketing the mandrel in polyolefin shrink tubing. When the braid/jacket mandrel are heated for shaping, the shrink tubing softens and the braided tube will slightly embed. This similarly creates a braid/mandrel assembly that has a partially masked inner braid surface for a follow up coating step. 
         [0062]      FIG. 5  shows a formed braided tube that has been coated in the silicone dispersion described above. The distal end may be made atraumatic for insertion in the delicate anatomy of the nasal cavity, for example by using a double layer  36  of the braided tube material, in contrast to the single layer  34  shown in  FIG. 4 . The double layer  36  may be provided by inverting the braided tube  20  to create a dual wall braided tube with an un-cut, rolled or rounded edge  32 . 
         [0063]      FIG. 6  shows a formed braided tube  20  having an inverted braid section  30  to create the rounded edge  32 . The rounded edge  32  can be dipped completely into a coating. This creates an impermeable surface in a simple way, although it may reduce flexibility or the ability to draw down and fold since both braid layers are bonded together. 
         [0064]      FIGS. 7A-7C  show an alternative to the rounded edge design of  FIG. 6 , with the benefit of the rounded edge  32  has no coating on the inner surface, while the outer surface is coated, and does not bond the layers together preserving a thinner wall and flexibility. 
         [0065]    Referring now to  FIG. 7A , the right side of the braided tube  20  is formed on a mandrel  22  and then coated. The left side is not formed or coated. Referring now to  FIG. 7B , the uncoated braid (left side) is inverted and loaded through the shaped and coated right side portion. Referring now to  FIG. 7C , the rounded edge  32  (formed via the inverting step) and the coated external surface and uncoated internal surface are shown. For comparison,  FIG. 8A  shows an access sheath with a straight edge while  FIG. 8B  shows an access sheath  40  with a rounded edge  32 . 
         [0066]    As is apparent from the description of  FIGS. 3-8B  above, a method of making a surgical access sheath may include placing a length of braided tube material over a mandrel; conforming the braided tube material to the shape of the mandrel; heating the braided tube material to heat set the braided tube material; removing the braided tube material from the mandrel; and cutting the heat set braided tube material to a desired length. The conforming step can be performed by at least partially wrapping tape over the braided tube material, or placing a shaping block having an internal opening complimentary to the mandrel, over the braided tube material. 
         [0067]    A monofilament material having round or flat fibers may be used as the braided tube material. A sheet or strip of braid material may also be used in place of a tube, with the sheet or strip formed into a tube during the manufacturing process. For example, a strip of braid material may be wrapped around the mandrel and formed into a tube via the heat setting. A coating may be applied to at least part of the heat set braided tube. 
         [0068]    Internal contact points of the braided tube material may optionally be embedded into the mandrel surface, and a coating applied onto at least part of the heat set braided material. One or both ends of the heat set braided material may be folded or rolled to form an atraumatic end. 
         [0069]      FIGS. 9A and 9B  show a finished access sheath  40 , and demonstrate its ability to conform to significant angulation of surgical tools  42  and  44 . The access sheath  40  can stretch as shown in  FIG. 9B  when surgical tools are angulated and apply a spreading load on the access sheath  40 . In typical endonasal skull base procedures, multiple surgical tools are used to stretch the nares in order to increase the angle formed by two surgical tools creating a triangulation rather than bringing the distal ends of the surgical tools together. The access sheath  40  can preferably stretch as much as or more than the tissue of the nares. The access sheath  40  can accommodate the varied anatomy of the human nares and stretch and contract to accommodate surgical tool requirements. 
         [0070]    The access sheath  40  may be compressed or folded for low profile placement and high profile working position. In a simple case the access sheath can be folded by hand and slid into the sinus manually. Loading tools or kits may also be used. 
         [0071]      FIG. 10A-10G  show a system or kit  50  for low-profile insertion of the access sheath  40 .  FIG. 10A  shows the access sheath  40  next to an elongated tubular loading tool  52 . The loading tool  52  has a flared proximal end  54  to aid in channeling the access sheath  40  into the elongated tubular body  62  of the loading tool  52 . The loading tool  52  has an slot  56  along one side to allow the access sheath  40  to be separated from the loading tool after it is placed in the nose of the patient.  FIG. 10B-10F  show the placement of the access sheath  40 . The access sheath  40  can be loaded via the loading tool  52  to 1) Compress and control the access sheath  40  into a compact volume; 2) provide a streamlined low profile shape for inserting the access sheath  40  into the narrow space of the nasal opening and cavity; and/or 3) provide a conduit for deploying the access sheath  40 . 
         [0072]    The loading tool  52  has a flared proximal end  54  to allow the access sheath  40  to be easily inserted into the loading tool  52  and compacted into a small volume. A tubular body  62  is joined to the flared proximal end  54  of the loading tool  52 . The tubular body  62 , which may be straight or have a slight taper towards the distal end, is designed to fit into the nasal opening. The slot  56  along the side of the loading tool  52  provides a conduit for the access sheath  40  to be deployed and released. 
         [0073]    The kit in  FIGS. 10A-10G  may be provided with an access sheath  40  comprising a braid material, and a loading tool  52  having a conical proximal end, and a tubular distal end, and the slot  56  extending along one side of the loading tool, along the entire length of the loading tool. The loading tool comprises a flexible material to allow the slot to be pushed open further, to better allow the sheath to moved out of the loading tool into the nose or other body cavity. The slot has a width equal to 25% to 45% of a minimum diameter of the tubular distal end. 
         [0074]    Turning to  FIG. 11A , in an alternative access sheath kit, the access sheath  40  may optionally be folded and slid into a tube  70 . The tube  70  may be a thin walled round or oval tube, optionally with an annular collar  74  at the back or proximal end to provide a grasping surface. The folded or rolled access sheath  40  may be inserted into the distal or proximal end of the tube. The plunger  72  is inserted into the proximal end as shown in  FIG. 11B . The tube  70  is then introduced into the nose. Advancing the plunger while holding the tube stationery pushes the access sheath  40  out of the distal end of the tube as shown in  FIG. 11C . The tube and plunger may then be withdrawn by pulling back on the tube, leaving the access sheath  40  in place in the nose. The plunger  72  may have an enlarged head  76  having a diameter greater than the collar  74  or the tube  70 , to limit the extent of travel of the plunger into the tube. 
         [0075]    As shown in  FIGS. 11A-11C , the surgical kit has an access sheath  40  made of a braided material, and a loading tool set including the tube  70  and the plunger  72  slidable into the tube. The access sheath  40  is foldable or compressible to fit into the tube, and with the access sheath expandable when ejected from the tube by the plunger. The tube may have an outside diameter of 5 to 20 mm and be transparent or translucent. 
         [0076]      FIG. 12A to 12C  show another kit using a folding instrument  80  to fold, introduce and deploy the access sheath  40 . The folding instrument  80  is a scissor-like device having a bottom jaw  82  having an elongated grooved channel  84 . The top jaw  86  is an elongated rod or beam pivotally attached to the bottom jaw  82 , with a handle at the back end of each jaw. 
         [0077]    In use the instrument  80  is opened, as shown in  FIG. 12A  and the access sheath  40  is placed between the open jaws  82  and  86 , or over one of the jaws. Squeezing the handles towards each other pivots the jaws towards a closed position shown in  FIG. 12B , with the access sheath folded between the jaws. The jaws are then inserted into the nasal cavity and opened slightly to release the access sheath. The instrument  80  is removed while the access sheath  40  is left in place. The instrument  80  can be re-inserted into the internal channel  45  of the access sheath  40  and then manipulated open and closed to help open and expand the access sheath as needed. 
         [0078]    The designs of  FIGS. 12A-12C  if provided as a surgical kit, includes the access sheath  40  made of a braid material, and the scissor-like loading tool having the first jaw pivotally attached to the second jaw, with the first jaw having a channel and the second jaw movable at least partially into the channel when the scissor-like loading tool is in a closed position, to fold the access sheath. 
         [0079]    Referring to  FIGS. 13A and 13B , a conical collar insert  90  may be placed in the angle section  154  and flare section  156  of the access sheath  40 , shown in  FIGS. 15-22 . The insert  90  may be made from a hard plastic or metal so that it is inherently lubricious relative to metal or plastic surgical tools  44 . The insert  90  provides a lubricious bearing surface at the angle and flare sections of the access sheath  40 , where surgical tools  44  extensively contact with the access sheath  40 . 
         [0080]      FIGS. 13B to 13E  show an alternative conical collar insert  100  which is a rigid collar having radial slots  102  to allow it to flex into a more open state in response to forces exerted by surgical tools  44 . This allows the surgical tools  44  to be more easily moved into larger acute angles relative to each other. The collar inserts  90  and  100  may each have a flared section  110  joined to a tubular section  112  having straight or parallel walls. Alternatively the tubular section  112  may have a reverse flare wherein it tapers outwardly towards the distal end. As shown in  FIGS. 13A and 13D , the flared section  110  has a shape and dimensions to allow it to fit and be attached into the flare section  156  of the access sheath  40 . The tubular section  112  is similarly configured to fit into the angle section  154  of the access sheath  40 . The inserts  90  and  100  may be attached to the access sheath  40  via adhesive, plastics welding, shrink fit, molded into place, snap fit, etc. 
         [0081]      FIG. 14  shows an access sheath  40  with a distal end  120  of an elastomer to create an atraumatic tip  122 . The elastomer can be an internal and external rim. Preferably the elastomer is only on the external surface so as not to create an internal surface of elastomer. This provides an atraumatic tip  122  but does not create an internal elastomeric surface that could result in a friction inducing surface at the distal end of the internal channel  45  of the access sheath  40 . The elastomer may be provided a cut edge of a single layer of braided tube material, or over the rounded edge  32  of a access sheath  40  having two layers of braided tube material at the edge. 
         [0082]    The elastomer may extend proximally 1-50 mm on the external surface of the access sheath  40 . The external extended elastomeric surface  124  provides a user selectable section that may be cut to a desired length. When cut, a portion of the external extended elastomeric surface  124  remains on the access sheath  40  and provides an atraumatic distal rim. An external rim of elastomer may similarly be used on the proximal end of the access sheath. This provides a section at the proximal end that maintains the integrity of the braided tube and avoid fraying. The external rim of elastomer on the proximal rim, if used, may only be on the external surface so as not to create friction on surgical tools passing through the internal channel  45 . 
         [0083]      FIGS. 15-22  show dimensions and angles which may be used for the access sheath  40 . The mandrel  22  may be sized and shaped to form an access sheath as shown in these Figures. In this example, the access sheath  40  has a body section  152 , and angle section  154  and a flare or conical section  156 . The sheath  40  may be formed of braid material as a one piece unit with the body section  152 , the angle section  154  and the flare section  156  integrally joined together. As shown in  FIG. 20 , the sheath  40  may have a thin flexible wall  158  having a thickness TT which allows the sheath to conform to the body orifice, or the inner wall of the patient&#39;s nostrils in the case of nasal access. The flare section  156  may be provided as a conical ring forming an angle DD of 120-160 or 130-150 degrees with the top wall of the angle section. The sheath  40  may have a single through internal channel  45  extending from a distal opening  162  to a proximal opening  165 . As shown in  FIGS. 18, 19 and 22 , the openings  162  and  165 , and the cross section of the body section  152 , may be generally in the shape of an oval or an ellipse. 
         [0084]    Referring to  FIGS. 15 and 17 , the distal opening  162  may lie in a plane forming an angle forming an angle BB with the bottom of the sheath  40 , with BB ranging from 95 to 125 or 100 to 115 degrees. As best shown in  FIG. 17 , the angle section  154  may be described as joined to the body section  152  at a vertical line  151 . The upper and lower walls of the sheath extend distally away from the vertical line  151  towards the distal opening  162  at acute angles to the vertical line  151 , which may the same or different angles. As shown in  FIG. 15 , the included angle CC between the top surface of the angle section  154  and the lower wall of the body section may range from 25 to 40 or 30 to 35 degrees. The angle PP in  FIG. 15  relating to the diverging angle of the top and bottom surfaces of the body section is typically 10-20 or 12-16 degrees. Dimension KK may be 8-16 or 10-14 mm, with dimensions MM and SS both generally about 65-85 or 70-80 mm. 
         [0085]    As shown in  FIGS. 15-17 , a surgical sheath  40  includes a conical section; an angle section joined to the conical section, with the conical section having a central axis AF not parallel to a central axis AN of the angle section; a body section joined to the angle section, with the body section having a length at least twice the length of the angle section; and the conical section, the angle section and the body section comprising a braid material. The sheath  40  may further include an insert  90 ,  100  inside of the conical section, with the insert made of a non-braid material. An elastomer coating may be provided on at least part of an external surface of the sheath. The sheath may have a rolled edge at its distal end. 
         [0086]    Turning to  FIGS. 15-16 and 20-22 , one or more ridges  64  may be provided on an outer surface of the body section  152 . The ridges may optionally be provided as rings extending continuously around the outside surface of the body section. The dimensions and angles shown in the drawings of all embodiments may typically be varied by 10, 20 or 30% depending on various design parameters. 
         [0087]    The angle section  154  may allow the proximal end of the sheath  40  to be more easily stretched and/or deflected. This allows for more versatile movement of surgical tools extending through the sheath during surgery. As shown in  FIGS. 15 and 17  the angle section  154  forms an irregular quadrilateral shape in cross section. In  FIG. 17  the angle section  154  may be defined by line F 4  along with segments or lines F 1 , F 2  and F 3 , with F 4  and F 2  forming a first acute angle and with F 1  and F 3  forming a second acute angle. Each of the sides or segments F 4 , F 1 , F 2  and F 3  forming the angle section  154  may also have different lengths. F 3  may be substantially perpendicular to F 2 . The angle section  154  may alternatively be described via a centerline AN perpendicular to and bisecting segment or line F 4  and intersecting a centerline AF of the flare section  156  at an angle AB of 5-30 or 10-20 degrees. 
         [0088]    One method for placing a surgical access sheath includes loading a surgical access sheath into a loading tool, with the surgical access sheath comprising a braid material, and with the loading tool having a conical proximal end, and a tubular distal end, and a slot extending from the conical proximal end to the tubular distal end; inserting the loading tool into a body orifice; inserting a surgical tool into an internal channel of the surgical access sheath; moving the surgical tool to move the surgical access sheath out of the loading tool through the slot; and withdrawing the loading tool from the body orifice. 
         [0089]    Another method for placing a surgical access sheath includes placing a surgical access sheath into a low profile delivery position, with the surgical access sheath comprising a braid material; loading the surgical access sheath into a tube; inserting the loading tool into a body orifice; moving a plunger into the tube to eject the surgical access sheath out of the tube and into the body orifice; and withdrawing the tube from the body orifice. 
         [0090]    Another method for placing a surgical access sheath includes providing a scissor-like loading tool having a first jaw pivotally attached to a second jaw, with the first jaw having a channel and the second jaw movable at least partially into the channel when the scissor-like loading tool is in a closed position; providing a surgical access sheath comprising a braid material, with the access sheath having an internal channel; placing the access sheath around one of the first jaw and the second jaw, while the jaws are in an open position; moving the jaws into the closed position, to fold and grasp the surgical access sheath; inserting the jaws into a body orifice; opening the jaws to release the surgical access sheath; and removing the jaws from the body orifice. 
         [0091]    A surgical kit includes an access sheath comprising a braid material; and a loading tool having a conical proximal end, and a tubular distal end, and a slot extending from the conical proximal end to the tubular distal end. The loading tool may comprise a flexible material. Typically the slot extends along an entire length of the loading tool. The slot may have a width equal to 25% to 45% of a minimum diameter of the tubular distal end. The access sheath may have a conical section, an angle section joined to the conical section, with the conical section having a central axis AF not parallel to a central axis AN of the angle section, a body section joined to the angle section, with the body section having a length at least twice the length of the angle section. Alternatively, the loading tool may have a tube and a plunger slidable into the tube, with the access sheath foldable or compressible to fit into the tube, and with the access sheath expandable when ejected from the tube by the plunger. If used, the tube may have an outside diameter of 5 to 20 mm, and it may be transparent or translucent. A scissor-like loading tool may also be used, with the scissor-like loading tool having a first jaw pivotally attached to a second jaw, with the first jaw having a channel and the second jaw movable at least partially into the channel when the scissor-like loading tool is in a closed position, to fold the access sheath. 
         [0092]    Thus, a novel surgical sheath and methods have been shown and described. Various changes and substitutions may of course be made without departing from the spirit and scope of the invention. The invention, therefore, should not be limited except by the following claims and their equivalents.