Patent Publication Number: US-2020288952-A1

Title: Sheath location indicator and overextension preventer

Description:
BACKGROUND 
     Existing devices that are used for bronchoscopy do not include means of preventing health care professionals (HCPs) from overextending the sheath and potentially damaging the airway walls. Most devices have a set length sheath that can be adjusted slightly to bring the sheath into the view of the endoscopic camera and bring it closer to the target tissue. This set length is adjusted from the handle, but there are no feedback mechanisms to prevent the HCP from overextending the sheath into the tissue. To avoid overextension, some HCPs will set the sheath extension length while the scope is outside of the body. They extend the sheath to the maximum length they feel comfortable with and then lock the sheath at that position. This takes extra time, though, and requires the HCPs to remove the scope from the body, if not done before beginning the procedure. 
     SUMMARY 
     The present invention includes an apparatus for controlling advancement of a sheath or a catheter relative to a scope (e.g., endoscope). An exemplary apparatus includes a flexible sheath that receives a medical device within an internal lumen and is received within a working channel of an endoscope, such as a bronchoscope. The apparatus also includes a component that is at least one of external or internal to the sheath. The component causes a change in longitudinal motion friction of the sheath above a predefined threshold amount as the sheath moves relative to an exit ramp of the endoscope. 
     In one aspect of the invention, the component includes a heat shrink material located around a distal section of the flexible sheath. The heat shrink is configured to make contact with a proximal end of the exit ramp and stop longitudinal motion of the sheath. When the longitudinal motion has stopped due to the heat shrink directly contacting with the proximal end of the exit ramp, the distal end of the sheath extends beyond the working channel of the endoscope by a predefined amount. 
     In another aspect of the invention, a longitudinal force required to move the sheath and the heat shrink through the exit ramp is greater than a longitudinal force needed to move the sheath and the heat shrink when the heat shrink is located proximally or distally of the exit ramp. 
     In still another aspect of the invention, the heat shrink has a proximal geometry that makes contact with a distal end of the exit ramp. When the proximal geometry of the heat shrink makes contact with the distal end of the exit ramp, the distal end of the sheath extends beyond the working channel of the endoscope by a predefined amount. 
     In yet another aspect of the invention, the component includes a laser cut hypotube that includes a distal section having a first flexibility value and a proximal section having a second flexibility value. The first flexibility value is greater than the second flexibility value. 
     In a further aspect of the invention, a longitudinal force required to move the sheath and the proximal section of the hypotube through the exit ramp is greater than a longitudinal force needed to move the sheath and the distal section of the hypotube through the exit ramp. 
     In yet further aspects of the invention, a longitudinal force required to move the sheath and the hypotube through the exit ramp experiences a sudden change causing a click-like feeling as the sheath and the hypotube moves relative to the exit ramp. 
     In still yet further aspects of the invention, the proximal section of the hypotube restricts distal movement of the sheath through the exit ramp. 
     Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the drawings: 
         FIG. 1-1  shows a perspective view of an endobronchial ultrasound (EBUS) bronchoscope capable of receiving a sheath device formed in accordance with an embodiment of the present invention; 
         FIG. 1-2  shows a close-up view of a distal end of the EBUS bronchoscope of  FIG. 1-1 ; 
         FIG. 2  shows a partial side view of a sheath device formed in accordance with an embodiment of the present invention; 
         FIG. 3  shows a cross-sectional view of a portion of the sheath device of  FIG. 2  positioned at a distal end of an EBUS scope; 
         FIG. 4  shows a cross-sectional view of the portion of the sheath device of  FIG. 2  at a different location relative to the EBUS scope; 
         FIG. 5  shows a cross-sectional view of the portion of the sheath device of  FIG. 2  at a different location relative to the EBUS scope; 
         FIG. 6  shows a side x-ray view of a sheath device formed in accordance with an embodiment of the present invention; 
         FIG. 7  shows a side, partial cross-sectional/x-ray view of a distal end of an EBUS scope with a sheath device formed in accordance with an embodiment of the present invention; 
         FIG. 8  shows a cross-sectional/x-ray view of a portion of a sheath device formed in accordance with an embodiment of the present invention; and 
         FIG. 9  shows a cross-sectional/x-ray view of a portion the sheath device of  FIG. 7  received within a working channel of an EBUS scope. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely illustrative in nature and is not intended to limit the present disclosure, application, or uses. The following description explains, by way of illustration only and not of limitation, various embodiments of devices for controlling advancement of a sheath of a medical device from an endoscope. It will be appreciated that various embodiments described herein may help to simplify the process of tissue aspiration. 
       FIGS. 1-1 and 1-2  shows an exemplary endoscope (e.g., an endobronchial ultrasound (EBUS) scope  20 , such as an Olympus bronchoscope UC-180F), that is capable of receiving a medical device  30  formed in accordance with embodiments of the present invention. The EBUS scope  20  includes a handle  24  with a port  26  for receiving the medical device  30  and an insertion tube  28  connected to the handle  24 . A distal end of the insertion tube  28  includes an ultrasound transducer head  40 , an exit port  42  for an internal lumen (i.e., working channel) that connects to the port  26 , and a camera  44  with or without a light. The medical device  30  passes through the working channel to extend at least partially out of the exit port  42 . 
     In one embodiment, the medical device  30  includes a needle  32  received within a sheath  34 . The sheath  34  includes an internal feature and/or an external feature at or near its distal that will provide feedback or an enhanced physical feeling or force to an operator once that feature reaches a predefined location at or near the exit port  42  or the distal end of the working channel. This feature provides feedback to the operator which will give them an indication of where the distal end of the sheath  34  is located relative to the distal end of the working channel within the EBUS scope  20 . In one embodiment, as the operator is feeding the sheath  34  through the bronchoscope, the operator will feel more pressure when the distal end of the sheath  34  is at or nearing the end of the working channel. Once the pressure is released or is noticeably reduced, then the operator knows the sheath  34  has exited the distal end of the working channel. 
       FIG. 2  shows an exemplary sheath external feature, which includes a piece of heat shrink  50  or comparable material that adheres to a sheath  60  near the distal end. The heat shrink  50  is sized to provide feedback (i.e., increased friction) as the sheath  60 , with the attached heat shrink  50 , reaches a ramp area  62  at an exit port of a working channel  64  of an EBUS scope ( FIG. 3 ). 
     As shown in  FIG. 4 , the sheath  60  has been advanced distally through the working channel  64  such that the heat shrink  50  has passed beyond the ramp area  62 . Once the heat shrink  50  has passed beyond the ramp  62  the amount of friction (i.e., pressure) is reduced to a point where it is noticeable by an operator manually manipulating an actuator that is linked to the sheath  60  at a handle. Thus, when the operator notices the greatly reduced friction due to the heat shrink  50  passing out of the ramp  62 , the operator would reduce the advancing force because they know the sheath  60  has exited the distal end of the scope. 
     As shown in  FIG. 5 , the sheath  60  has been retracted such that the proximal end of the heat shrink  50  makes contact with the opening of the ramp  62 . When the sheath  60  is positioned as shown in  FIG. 5 , the distal end of the sheath  60  is properly positioned relative to the ultrasound transducer and any surrounding tissue. The operator knows that the heat shrink  50  is located at the opening of the ramp  62  when there is a change (increase) in the retraction force. This allows the operator to pull the sheath  60  back to reduce the damage risk and still know the sheath  60  is out of the working channel. A little extra force will be needed to retract the sheath  60  through the ramp and into the working channel  64 . 
     In one embodiment, a mechanical design element(s) included in a sheath functions to aid in positioning the sheath at a predetermined set position. The mechanical design element(s) minimizes the amount of sheath protruding from the working channel and/or eliminates sheath movement associated with needle activation. 
     As shown in  FIG. 6 , a sheath  70  includes an insert component  72  that acts as the mechanical design element. In one embodiment, the insert component  72  is a laser-cut hypotube that includes a first portion  76  and a second portion  78 . The second portion  78  includes a feature(s) (e.g., etchings) that provides for increased flexibility. The first portion  76  has less or no flexibility features and is thus stiffer than the second portion  78 . The stiffness value of the first portion  76  is selected to not allow the first portion  76  to extend through an exit ramp of an EBUS bronchoscope  80 . In one embodiment, the stiffness value of the first portion  76  is selected to provide a discernable feedback (i.e., click into place) as the user advances the first portion  76  up to and/or through the exit ramp. 
     In one embodiment, as shown in  FIG. 7 , an insert component  72 - 2  includes a proximal portion  74 , a distal portion  78 - 2  and a middle portion  76 - 2  located between the proximal and distal portions  74 ,  78 - 2 . The proximal and distal portions  74 ,  78 - 2  include features (e.g., etchings) that provide for increased flexibility. The middle portion  76 - 2  has less or no flexibility features and is thus stiffer than the distal portion  78 - 2 . The stiffness value of the middle portion  76 - 2  and/or the length of the middle portion  76 - 2  is selected to not allow the middle portion  76 - 2  to extend through an exit ramp of an EBUS bronchoscope  80 . In one embodiment, the stiffness value of the middle portion  76 - 2  is selected to provide a discernable feedback (i.e., click into place) as the user advances the middle portion  76 - 2  up to and/or through the exit ramp. The flexible proximal portion  74  provides added protection of the scope from a needle without adding too much stiffness, by decreasing insertion forces and/or reducing issues with scope durability. 
     As shown in  FIGS. 8 and 9 , a medical device includes a heat shrink collar  100  that is placed around a sheath  102  at a distal end. The heat shrink collar  100  is offset from the distal end of the sheath  102  so that when the sheath  102  is inserted into the scope, the sheath  102  extends outside of the scope when the heat shrink collar  100  catches at a ferrule/ramp  106  inside a scope  110 . In one embodiment, the sheath  102  does not extend into a field of view of a camera (˜2 mm). The heat shrink  100  has a predefined length, width, and stiffness in order for the sheath  102  to catch at the base of the ramp  106 . The stiffness caused by the heat shrink  100  is not too stiff to prevent the medical device from getting around other bends of the scope  110  and has a low to non-existent risk of getting wedged into the ramp  106 . In one embodiment, the edges of the heat shrink  100  are reflowed to prevent unwanted damage to the scope  110 . A certain geometric shape of the edges of the heat shrink  100  may be beneficial for catching the medical device at the base of the ramp  106  and thus preventing overextension of the sheath  102  in the distal direction and providing a location guide in the proximal direction after extension. 
     The sheath  102  may also include a sheath insert  112  inserted into the distal end. The sheath insert  112  protects the scope when a needle (not shown) is received within the sheath  102 . The heat shrink  100  may be located proximally from the sheath insert  112  or may partially overlap the sheath insert  112 . Any of the sheath inserts/insert components may be a laser cut hypotube or comparable material. 
     Embodiments 
     A. An apparatus comprising: a flexible sheath configured to receive a medical device within an internal lumen and configured to be received within a working channel of an endoscope; and a component received at least one of externally on or internally within the sheath, the component configured to cause a change in longitudinal motion friction of the sheath above a predefined threshold amount as the sheath moves relative to an exit ramp of the endoscope. 
     B. The apparatus of B, wherein the component comprises a heat shrink material located around a section of the flexible sheath. 
     C. The apparatus of C, wherein the heat shrink is configured to make contact with a proximal end of the exit ramp and stop longitudinal motion of the sheath. 
     D. The apparatus of C, wherein when the longitudinal motion has stopped due to the heat shrink directly contacting with the proximal end of the exit ramp, the distal end of the sheath extends beyond the working channel of the endoscope by a predefined amount. 
     E. The apparatus of B, wherein a longitudinal force required to move the sheath and the heat shrink through the exit ramp is greater than a longitudinal force needed to move the sheath and the heat shrink when the heat shrink is located proximally or distally of the exit ramp. 
     F. The apparatus of any of A-E, wherein the heat shrink is configured to have a proximal geometry configured to make contact with a distal end of the exit ramp. 
     G. The apparatus of F, wherein when the proximal geometry of the heat shrink makes contact with the distal end of the exit ramp, the distal end of the sheath extends beyond the working channel of the endoscope by a predefined amount. 
     H. The apparatus of A, wherein the component comprises a laser cut hypotube, the laser cut hypotube comprises: a distal section having a first flexibility value; and a proximal section having a second flexibility value, wherein the first flexibility value is greater than the second flexibility value. 
     I. The apparatus of H, wherein a longitudinal force required to move the sheath and the proximal section of the hypotube through the exit ramp is greater than a longitudinal force needed to move the sheath and the distal section of the hypotube through the exit ramp. 
     J. The apparatus of H, wherein a longitudinal force required to move the sheath and the hypotube through the exit ramp experiences a sudden change causing a click-like feeling as the sheath and the hypotube moves relative to the exit ramp. 
     K. The apparatus of H, wherein the proximal section of the hypotube restricts distal movement of the sheath through the exit ramp. 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. 
     Although the preferable embodiments of the present invention have been described hitherto, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. 
     In addition, the invention is not limited by the above description and is limited only by the scope of appended claims.