Patent Publication Number: US-2021162181-A1

Title: Puncture needle and method of using guide wire

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of International Application PCT/JP2018/027058, with an international filing date of Jul. 19, 2018, which is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a puncture needle and a method of using a guide wire. 
     BACKGROUND ART 
     There is a known technique in which a guide wire is introduced into the inside of a body via an inner hole of a needle tube that has punctured the tissue of the body (for example, refer to US Patent Application Publication No. 2016/0157839). 
     In US Patent Application Publication No. 2016/0157839, in order to prevent the guide wire from being damaged by the edge of the distal end of the needle tube, an inner cylinder, which protrudes from the distal end of the needle tube, is inserted into the inner hole of the needle tube and the guide wire is made to protrude through an inner hole of the inner cylinder. 
     SUMMARY OF INVENTION 
     An aspect of the present invention provides a puncture needle that includes: a tubular sheath having a longitudinal axis; a needle tube that is arranged inside the sheath so as to be movable along the longitudinal axis and that has a needle tip at a distal end thereof; a protective tube that is arranged inside the needle tube so as to be movable along the longitudinal axis and that has a lumen into which a guide wire is inserted so as to be movable along a direction of the longitudinal axis; a needle slider that is connected to a proximal end of the needle tube; and a tube slider that is supported so as to be able to move in directions along the longitudinal axis relative to the needle slider and that is connected to the proximal end of the protective tube. The needle tube has a step portion formed at a position midway along the needle tube in the longitudinal direction. The protective tube has a protrusion, which protrudes radially outward, on at least part of an outer peripheral surface thereof at a position which is nearer a proximal end side of the protective tube than the step portion is. A distal end of the protective tube is positioned at a position so as to protrude from the distal end of the needle tube when the protrusion abuts the step portion from the proximal end side of the protective tube. The needle slider is provided with a locking portion that abuts the tube slider when the tube slider is moved forward toward the distal end side relative to the needle slider, and the protrusion is maintained in a state of pressing against the step portion when the tube slider is moved forward to a position where the tube slider abuts the locking portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a partial longitudinal sectional view illustrating a tip portion of a puncture needle according to an embodiment of the present invention. 
         FIG. 2  is a perspective view illustrating the entire puncture needle in  FIG. 1 . 
         FIG. 3  is a longitudinal sectional view illustrating the entire puncture needle in  FIG. 2 . 
         FIG. 4  is a perspective view illustrating the tip portion of the puncture needle in  FIG. 1 . 
         FIG. 5  is a partial longitudinal sectional view illustrating a state in which a protective tube is made to protrude from a needle tip of the puncture needle in  FIG. 1 . 
         FIG. 6  is a longitudinal sectional view illustrating the relationship between a tube slider and a needle slider of the puncture needle in  FIG. 1 . 
         FIG. 7  is a longitudinal sectional view illustrating an example of the positional relationship between a raising platform of an endoscope that has the puncture needle in  FIG. 1  inserted into a channel thereof and a joint section provided in the puncture needle. 
         FIG. 8  is a longitudinal sectional view illustrating another example of the positional relationship between the raising platform of the endoscope that has the puncture needle in  FIG. 1  inserted into the channel thereof and the joint section provided in the puncture needle. 
         FIG. 9  is a partial longitudinal sectional view illustrating a modification of the puncture needle in  FIG. 1 . 
         FIG. 10  is a perspective view illustrating another modification of the puncture needle in  FIG. 1 . 
         FIG. 11  is a longitudinal sectional view illustrating another modification of the puncture needle in  FIG. 1 . 
         FIG. 12  is a longitudinal sectional view illustrating another modification of the puncture needle in  FIG. 1 . 
         FIG. 13  is a longitudinal sectional view illustrating another modification of a puncture needle tip in  FIG. 1 . 
         FIG. 14  is a longitudinal sectional view illustrating another modification of the puncture needle tip in  FIG. 1 . 
         FIG. 15  is a longitudinal sectional view illustrating another modification of the puncture needle tip in  FIG. 1 . 
         FIG. 16  is a perspective view illustrating another modification of the puncture needle tip in  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereafter, a puncture needle  1  and a method of using a guide wire  15  according to an embodiment of the present invention will be described while referring to the drawings. 
     As illustrated in  FIG. 1 , the puncture needle  1  according to this embodiment includes a tubular sheath  2  having a longitudinal axis, a needle tube  3  that is arranged inside the sheath so as to be movable along the longitudinal axis, and a protective tube  4  that is arranged so as to be movable inside the needle tube  3  in the longitudinal axis directions. 
     As illustrated in  FIGS. 2 and 3 , the puncture needle  1  includes an operation part body  5  that is grasped by an operator, a sheath slider  6  to which a proximal end of the sheath  2  is fixed and that is supported so as to be movable in the longitudinal axis directions with respect to the operation part body  5 , a needle slider  7  that is supported so as to be movable in directions along the longitudinal axis with respect to the sheath slider  6 , and a tube slider  8  that is supported so as to be movable in the longitudinal axis directions with respect to the needle slider  7 . The sheath slider  6  is provided with a fixing screw  9  for fixing the sheath slider  6  to the operation part body  5  at an arbitrary position. 
     As illustrated in  FIG. 4 , the sheath  2  is formed in a tubular shape having a circular cross section. The proximal end of the sheath  2  is fixed to the sheath slider  6 . 
     As illustrated in  FIG. 4 , the needle tube  3  has a circular cross section, which has an outer diameter that is slightly smaller than the inner diameter of the sheath  2 , and the needle tube  3  has a needle tip  10  having a shape resulting from the distal end of the needle tube  3  being diagonally cut at a plane intersecting the longitudinal axis. The proximal end of the needle tube  3  is fixed to the needle slider  7 . The needle tube  3  can be moved forward and backward in the longitudinal axis directions relative to the sheath  2  by moving the needle slider  7  along the longitudinal axis directions relative to the sheath slider  6 . The sheath slider  6  is provided with a needle stopper  11  that adjustably defines a forward position of the needle slider  7  with respect to the sheath slider  6 . 
     As illustrated in  FIG. 4 , the protective tube  4  also has a circular cross section that is slightly smaller than the inner diameter of the needle tube  3 . The inner diameter of the protective tube  4  is larger than the outer diameter of the guide wire  15 . In other words, the guide wire  15  can be inserted into the inside of a lumen of the protective tube  4  so as to be movable in the longitudinal axis directions. The proximal end of the protective tube  4  is fixed to the tube slider  8 . The protective tube  4  can be moved forward and backward in the longitudinal axis directions relative to the needle tube  3  by moving the tube slider  8  along the longitudinal axis directions relative to the needle slider  7 . 
     The protective tube  4  is composed of a resin material having a comparatively high rigidity such as polyether ether ketone resin (PEEK). Polypropylene or PET, as resin materials having a comparatively high rigidity, may be used instead of PEEK. 
     The protective tube  4  may be formed of a material that can be detected by an ultrasound sensor. In addition, the tip portion of the protective tube  4  may be coated with a metal powder. This enables the protruding state of the protective tube  4  to be readily visible under x-ray or ultrasound endoscopy. 
     In this embodiment, as illustrated in  FIG. 1 , the needle tube  3  has a joint section  12  at a position midway therealong in the longitudinal axis direction and two tubular parts  13  that each include either the needle tip  10  or the proximal end of the needle tube  3 . The joint section  12  is formed by arranging the end surfaces of the two tubular parts (needle tip portion and needle base portion)  13 , which constitute the needle tube  3 , in the longitudinal axial direction with a space therebetween and joining the end surfaces to each other in a state where the two tubular parts  13  have been fitted into the inside of a large-diameter connection tube  14 . Thus, inside the joint section  12 , a step portion  16  is formed by the connection tube  14  and a proximal end surface of the tubular part  13  arranged at the side nearer the distal end, the inner diameter decreasing by one step in the step portion  16  in the direction toward the distal end. 
     A protrusion  17  that protrudes radially outward is provided on the outer surface of the protective tube  4  at a position that is midway therealong in the longitudinal axis direction and coincides with the connection tube  14 . The outer diameter of the protrusion  17  is set to be larger than the inner diameter of the tubular parts  13  of the needle tube  3  and smaller than the inner diameter of the connection tube  14  of the needle tube  3 . 
     Thus, the amount of movement of the protective tube  4  in the longitudinal axis direction with respect to the needle tube  3  is restricted to a distance between a position where the protrusion  17  abuts the proximal end surface of the distal end-side tubular part  13  and a position where the protrusion  17  abuts the distal end surface of the proximal-end-side tubular part  13 . As illustrated in  FIG. 5 , the distal end of the protective tube  4  is positioned at a position where the distal end of the protective tube  4  protrudes from the distal end of the needle tube  3  by a prescribed dimension at the position where the protrusion  17  abuts the step portion  16  formed by the proximal end surface of the distal end-side tubular part  13 . 
     As illustrated in  FIG. 6 , the needle slider  7  is provided with a stopper (locking portion)  18  that abuts the tube slider  8  when the tube slider  8  is moved forward in the longitudinal axis direction to the maximum extent. A fixing mechanism  19  that fixes the tube slider  8  to the needle slider  7  in a state where the tube slider  8  has abutted the stopper  18  is provided between the needle slider  7  and the tube slider  8 . 
     The fixing mechanism  19 , for example, includes a recess  20  that is provided in the needle slider  7  and a hook  21  that is provided on the tube slider  8 , and backward movement of the tube slider  8  relative to the needle slider  7  is restricted as a result of the hook  21  catching in the recess  20  when the tube slider  8  is moved forward. 
     Here, the maximum stroke of the tube slider  8  with respect to the needle slider  7  is set to be greater than the amount of protrusion of the protective tube  4  from the needle tip  10  when the tube slider  8  is moved forward to a position where the protrusion  17  of the protective tube  4  abuts the step portion  16  of the needle tube  3 . 
     In other words, when the tube slider  8  is moved forward relative to the needle slider  7 , the protrusion  17  of the protective tube  4  abuts the step portion  16  of the needle tube  3  in the middle of the stroke and any further protrusion of the protective tube  4  beyond the needle tip  10  is restricted. At this point, further forward movement of the tube slider  8  relative to the needle slider  7  is possible, and the protective tube  4  is made to elastically deform by an amount equivalent to the gap inside the needle tube  3  by moving the tube slider  8  forward relative to the needle slider  7 . When the tube slider  8  is moved forward relative to the needle slider  7  by the maximum stroke, the tube slider  8  abuts the stopper  18  and further forward movement of the tube slider  8  is restricted, and the hook  21  catches in the recess  20  of the fixing mechanism  19  and backward movement of the tube slider  8  relative to the needle slider  7  is restricted. 
     Thus, the protective tube  4  is arranged so as to protrude from the needle tip  10  of the needle tube  3  by a prescribed dimension and the protrusion  17  of the protective tube  4  is maintained in a state in which the protrusion  17  is pressed against the step portion  16  of the needle tube  3  by the elastic deformation of the protective tube  4 . As a result, the protective tube  4  is maintained in a state of protruding from the needle tip  10  of the needle tube  3  by a predetermined dimension, even if there is a difference between the path lengths of the needle tube  3  and the protective tube  4  due to the needle tube  3  being bent. 
     Hereafter, a method of using the guide wire  15  in which the puncture needle  1  according to this embodiment is used will be described. 
     In order to position the guide wire  15  inside a body using the puncture needle  1  according to this embodiment, first, the needle slider  7  is moved backward relative to the sheath slider  6  to the most rearward point, and the tube slider  8  is moved backward relative to the needle slider  7  to the most rearward point (second position). As a result, the needle tip  10  of the needle tube  3  is arranged so as to be retracted into the inside of the sheath  2 , and the protective tube  4  is arranged so as to be retracted toward the proximal end side from the needle tip  10  of the needle tube  3  and preparation of the puncture needle  1  is thus completed. 
     The sheath  2  of the thus-prepared puncture needle  1  is inserted from an opening at the proximal end of a channel  110  of an ultrasound endoscope (endoscope)  100 , which includes an ultrasound sensor that is not illustrated, up to the vicinity of the position of the distal end of the channel  110 . In this state, the ultrasound endoscope  100  is inserted into the inside of the stomach (first lumen) while acquiring tomographic images of the inside of the body by operating the ultrasound sensor and checking the acquired tomographic images. The opening at the distal end of the channel  110  in the ultrasound endoscope  100  is then arranged opposite the part of the stomach wall that is to be punctured. 
     In this state, the sheath slider  6  is moved forward relative to the operation part body  5  so that the distal end of the sheath  2  protrudes from the opening at the distal end of the channel  110 . Then, the needle slider  7  is moved forward relative to the sheath slider  6  with the distal end of the sheath  2  positioned opposite the part of the stomach wall that is to be punctured. As a result, the needle tip  10  of the needle tube  3  protrudes from the inside of the sheath  2 , the part of the stomach wall opposite the distal end of the sheath  2  is punctured by the needle tube  3 , and a through hole is formed by the needle tube  3  puncturing the stomach and the bile duct (second lumen) adjacent to the outside of the stomach. 
     Then, the tube slider  8  is moved forward relative to the needle slider  7  with the needle tube  3  protruding to a position where the needle tube  3  will pass through the through hole. 
     When the tube slider  8  is moved forward, the protective tube  4  is moved forward relative to the needle tube  3 , and as illustrated in  FIG. 5 , the protective tube  4  is moved to a position where the distal end of the protective tube  4  protrudes from the needle tip  10  of the needle tube  3  (first position). 
     Then, further protrusion of the protective tube  4  is restricted by the protrusion  17  provided on the protective tube  4  abutting, from the proximal end side, the step portion  16  provided on the inner surface of the needle tube  3 . In this case, in this embodiment, even in the state where movement of the distal end of the protective tube  4  is restricted, the tube slider  8  can be moved further forward relative to the needle slider  7 , and as illustrated in  FIG. 6 , the tube slider  8  is fixed by the fixing mechanism  19  at a position where the tube slider  8  abuts the stopper  18 . 
     In other words, the protective tube  4  is elastically deformed by an amount equivalent to a gap inside the needle tube  3 , and as a result, the protective tube  4  is maintained in a state where the distal end is constantly urged forward and the protrusion  17  of the protective tube  4  is pressed against the step portion  16  inside the needle tube  3  from the proximal end side. Therefore, the protective tube  4  is maintained in a state of protruding from the needle tip  10  by an appropriate amount even when there is a difference between the path lengths of the needle tube  3  and the protective tube  4  as a result of the needle tube  3  being bent due to the insertion path thereof inside the body cavity. 
     In this state, the guide wire  15  is inserted into the lumen of the protective tube  4  from the proximal end side of the protective tube  4 , as illustrated in  FIG. 1 , and the guide wire  15  can be prevented from coming into contact with the needle tip  10  by making the guide wire  15  protrude from the distal end of the protective tube  4 , as illustrated in  FIG. 4 . In other words, since the protective tube  4  is arranged so as to line the inner surface of the needle tip  10 , there is an advantage that it is possible to reliably prevent the occurrence of a problem in which the guide wire  15 , which is made to protrude or be retracted from the distal end of the protective tube  4 , contacts and rubs against the needle tip  10 . 
     After that, the guide wire  15  can be positioned with the guide wire  15  extending from the stomach to the bile duct by removing the needle tube  3  and the protective tube  4  from the through hole. 
     A tip portion of a stent deploying device, which is not illustrated, is inserted into the bile duct along a guide wire X that has been positioned in the bile duct from the stomach. The wall of the stomach and the wall of the bile duct can be connected to each other by a stent by deploying a stent from the stent deploying device, the distal end of which has been inserted into the bile duct, and then dilating the distal end of the deployed stent in the bile duct and dilating the proximal end of the stent in the stomach. 
     Prior to deploying the stent to the position of the wall of the bile duct, a device for dilating the hole in the wall, such as a balloon dilator, may be inserted along the guide wire  15  up to the vicinity of the wall of the bile duct in order to dilate the hole in the wall of the bile duct in advance before positioning the stent. Dilation of a hole in a wall is not limited to being performed only on the wall of the bile duct, and may instead be performed only on the wall of the stomach or on both the wall of the bile duct and the wall of the stomach. 
     In order to maintain the protective tube  4  in a state of protruding from the needle tip  10  regardless of how the needle tube  3  and the protective tube  4  are bent by simply maintaining the protrusion  17  of the protective tube  4  in a state of abutting the step portion  16  provided on the needle tube  3 , the step  16  and the protrusion  17  are preferably arranged as far as possible toward the distal end of the puncture needle  1 . However, provided that the protective tube  4  can be maintained in a state of protruding from the needle tip  10  for realistically anticipated curvatures, the step portion  16  and protrusion  17  may be arranged at the proximal end side. 
     In particular, as illustrated in  FIGS. 7 and 8 , in the case where the ultrasound endoscope  100  includes an observational optical system  120  and a raising platform  130  that presses and bends the tip portion of the needle tube  3  in a radial direction, in a state where the distal end of the sheath  2 , which extends along the channel  110  provided in the ultrasound endoscope  100  and has been made to protrude from the distal end of the channel  110 , is arranged inside the observational field of view of the observational optical system  120  and the needle slider  7  has been maximally moved forward with respect to the sheath slider  6 , the step portion  16  and the protrusion  17  are preferably not aligned with the raising platform  130 . This is because it is difficult for the raising platform  130  to bend the parts where the step portion  16  and the protrusion  17  are provided due to the increased rigidity provided by the connection tube  14 . 
     In other words, it is preferable that the step portion  16  and the protrusion  17  be arranged nearer the proximal end side than the proximal end of the raising platform  130  is, as illustrated in  FIG. 7 . Alternatively, as illustrated in  FIG. 8 , the step portion  16  and the protrusion  17  may be arranged nearer the distal end side than the part that is bent by the raising platform  130  is. 
     The needle tip  10  of the needle tube  3  and the tip portion of the protective tube  4  may be positioned on the scanning plane of ultrasound waves generated by the ultrasound sensor when the needle tube  3  has been moved forward until the protrusion  17  abuts the step portion  16  with the distal end of the sheath  2  positioned inside the observational field of view of the observational optical system  120 . 
     The puncture needle  1  may be used together with an endoscope without an ultrasound sensor instead of the ultrasound endoscope  100 . 
     In the present embodiment, the step portion  16  is formed by arranging the end faces of the two tubular parts  13  forming the needle tube  3  so as to be spaced apart in the longitudinal axis direction and then joining together the end surfaces in a state where the two tubular parts  13  have been fitted into the inside of the large-diameter connection tube  14 , but alternatively, the step portion  16  may be provided only on the distal end side by joining a tubular member  24 , which has a larger diameter than the needle tube  3 , to the proximal end of the needle tube  3  having the needle tip  10 , as illustrated in  FIG. 9 . 
     In this embodiment, the step portion  16  is formed by the connection tube  14 , but alternatively, as illustrated in  FIG. 10 , the step portion  16  may be formed by providing a slit  22  that extends in the longitudinal axis direction at a position midway along the needle tube  3  in the longitudinal axis direction and arranging the protrusion  17  of the protective tube  4  inside the slit  22 . The protective tube  4  can be maintained in a state of protruding from the needle tip  10  by making the protrusion  17  of the protective tube  4  abut the end surface of the slit  22 . 
     In this embodiment, an inclined portion  25  that is inwardly radially inclined may be provided on an inner surface of the connection tube  14 , as illustrated in  FIG. 11 . In this case, the inclined portion  25  is formed so as to be gradually inclined radially inward with increasing proximity to the step portion  16  from a position a predetermined range away from the step portion  16  on the proximal end side and so as to contact the outer surface of the protective tube  4  at the position of the step portion  16 . The protrusion  17  of the protective tube  4  is preferably provided on the opposite side from the inclined portion  25  with the protective tube  4  interposed therebetween. 
     In this embodiment, as illustrated in  FIG. 12 , the needle tube  3  need not include the connection tube  14  and may be formed of a single tubular part  13 . In this case, a protruding portion  26 , which protrudes radially inward, is provided on the inner surface of the tubular part  13  and the step portion  16  is formed by this protruding portion  26  and the inner surface of the tubular part  13 . As a result, when the protective tube  4  is moved forward and made to protrude from the needle tip  10  of the needle tube  3 , the protrusion  17  of the protective tube  4  abuts the step portion  16  formed by the protruding portion  26  of the tubular part  13 . 
     As illustrated in  FIG. 3 , the needle slider  7  may include an engagement portion  23  that engages with the tube slider  8  when the needle slider  7  is moved forward along the longitudinal axis with respect to the sheath slider  6 . As a result, puncturing can be performed using the needle tube  3  while maintaining the positional relationship between the needle tube  3  and the protective tube  4  constant. 
     In n this embodiment, an example of the fixing mechanism  19  that includes the recess  20  provided in the needle slider  7  and the hook  21  provided on the tube slider  8  has been illustrated, but alternatively, a mechanism may be employed that allows the two objects to be fixed to and released from each other via screw fastening. 
     In this embodiment, as illustrated in  FIG. 13 , a protective tube in which the inner surface of the tip is a chamfered tapered surface may be used as the protective tube  4 . Thus, it is possible to suppress damage to the guide wire  15  caused by a large pressure acting on the outer surface of the guide wire  15  from the inner surface of the distal end of the protective tube  4  when the guide wire  15  is made to protrude from the protective tube  4 . As illustrated in  FIG. 14 , the inner surface of the distal end of the protective tube  4  may be a rounded surface, or as illustrated in  FIG. 15 , the inner diameter of the protective tube  4  may gradually increase with increasing proximity to the distal end of the protective tube  4  from a position a predetermined distance away from the distal end of the protective tube  4  on the proximal end side. 
     In this embodiment, as illustrated in  FIG. 16 , a spiral cut (for example, a laser cut) may be formed in the outer peripheral surface of the tubular part  13  that is located nearer the distal end side than the connection tube  14  of the needle tube  3 . In this case, the tubular part  13  that is located nearer the proximal end side than the connection tube  14  of the needle tube  3  is formed of stainless steel. This enables the tubular part  13  that is nearer the distal end side than the connection tube  14  to readily follow the curved shape of the endoscope while maintaining pushability in the tubular part  13  that is nearer the proximal end side than the connection tube  14 . 
     As a result, the following aspect is read from the above described embodiment of the present invention. 
     An aspect of the present invention provides a puncture needle that includes: a tubular sheath having a longitudinal axis; a needle tube that is arranged inside the sheath so as to be movable along the longitudinal axis and that has a needle tip at a distal end thereof; a protective tube that is arranged inside the needle tube so as to be movable along the longitudinal axis and that has a lumen into which a guide wire is inserted so as to be movable along a direction of the longitudinal axis; a needle slider that is connected to a proximal end of the needle tube; and a tube slider that is supported so as to be able to move in directions along the longitudinal axis relative to the needle slider and that is connected to the proximal end of the protective tube. The needle tube has a step portion formed at a position midway along the needle tube in the longitudinal direction. The protective tube has a protrusion, which protrudes radially outward, on at least part of an outer peripheral surface thereof at a position which is nearer a proximal end side of the protective tube than the step portion is. A distal end of the protective tube is positioned at a position so as to protrude from the distal end of the needle tube when the protrusion abuts the step portion from the proximal end side of the protective tube. The needle slider is provided with a locking portion that abuts the tube slider when the tube slider is moved forward toward the distal end side relative to the needle slider, and the protrusion is maintained in a state of pressing against the step portion when the tube slider is moved forward to a position where the tube slider abuts the locking portion. 
     According to this aspect, when the protective tube, which is housed inside the needle tube, is moved forward relative to the needle tube after the tissue has been pierced by the needle tube, further forward movement of the protective tube relative to the needle tube is restricted by the protrusion provided on at least part of the outer peripheral surface of the protective tube abutting the step portion provided in the needle tube. At this time, the distal end of the protective tube is positioned so as to protrude from the distal end of the needle tube, and therefore it is possible to prevent the protective tube from excessively protruding from the distal end of the needle tube and to more reliably prevent the guide wire that passes through the inside of the lumen of the protective tube from contacting the needle tip of the needle tube. 
     With this configuration, when an operator moves the tube slider forward relative to the needle slider in order to cause the protective tube to protrude from the needle tip of the needle tube, the operator is able to recognize that the protective tube has moved forward to a position where the protrusion amount is restricted by the protrusion pressing against the step portion as a result of the tube slider having been moved forward to a position where the tube slider abuts the locking portion. 
     In the above-described aspect, the needle tube may include a needle tip portion that includes the needle tip of the needle tube, a needle base portion that includes a proximal end of the needle tube, and a connection tube that allows the needle tip portion to be fitted inside thereof on a distal end side thereof and allows the needle base portion to be fitted inside thereof on a proximal end side thereof, and the step portion may be formed by the connection tube and a proximal end surface of the needle tip portion fitted into the connection tube such that an inner diameter decreases by one step in the step portion toward the distal end of the needle tube. 
     With this configuration, when the protective tube is moved forward relative to the needle tube, the protrusion on the protective tube moves inside the connection tube along the longitudinal axis toward the distal end side and further forward movement of the protective tube relative to the needle tube is restricted by the protrusion abutting the proximal end surface of the needle tip portion of the step portion. 
     In the above-described aspect, a protrusion amount of the protective tube from the needle tip in a state where the tube slider has been moved forward to the position where the tube slider abuts the locking portion may be smaller than a maximum stroke amount of the tube slider. 
     With this configuration, the protective tube can be made to protrude from the distal end of the needle tube by an appropriate amount of protrusion at the position where the tube slider has been maximally moved forward and the protective tube can be more securely retracted toward the proximal end side from the distal end of the needle tube at the position where the tube slider has been maximally moved backward. 
     In the above-described aspect, the puncture needle may further include a fixing mechanism that fixes the tube slider to the needle slider in a state where the tube slider has abutted the locking portion. 
     With this configuration, when the tube slider is fixed to the needle slider by the fixing mechanism, the protrusion presses against the step portion and a state where the protective tube protrudes from the distal end of the needle tube by the appropriate protrusion amount can be maintained. 
     In the above-described aspect, the puncture needle may further include: an operation part body; and a sheath slider that is supported so as to be movable along the longitudinal axis relative to the operation part body and that is connected to a proximal end of the sheath. The needle slider may be supported so as to be movable in directions along the longitudinal axis with respect to the sheath slider. 
     With this configuration, the sheath can be moved forward by moving the sheath slider forward with respect to the operation part body in the longitudinal axis direction and the needle tube can be made to protrude from the distal end of the sheath by moving the needle slider forward with respect to the sheath slider in the longitudinal axis direction. 
     In the above-described aspect, the needle slider may include an engagement portion that engages with the tube slider when the needle slider is moved forward relative to the sheath slider. 
     With this configuration, when the needle slider is moved forward relative to the sheath slider, the needle tube is moved forward relative to the sheath. At this time, since the engagement portion provided on the needle slider engages with the tube slider, the protective tube is also moved forward together with the forward movement of the needle tube. As a result, the distal end of the protective tube can be held at a position close to the needle tip of the needle tube and the distal end of the protective tube can be quickly made to protrude from the needle tip after puncturing is performed using the needle tube. 
     In the above-described aspect, the tip portion of the protective tube may be coated with a metal powder. 
     This configuration enables the protrusion state of the protective tube from the distal end of the needle tube to be readily visible under X-ray or ultrasound endoscopy. 
     In the above-described aspect, the puncture needle may be inserted into a channel of an endoscope that includes an observational optical system, the channel, and a raising platform that is arranged at a distal end of the channel, and in a state where a distal end of the sheath, which extends along the channel and has been made to protrude from the distal end of the channel, is arranged inside an observational field of view of the observational optical system and the needle slider has been moved maximally forward with respect to the sheath slider, the step portion may be located nearer the proximal end side than a proximal end of the raising platform is. 
     With this configuration, the puncture needle is inserted into the channel of the endoscope, the distal end of the sheath is arranged inside the observational field of view of the observational optical system by moving the sheath slider forward, and the needle tip of the needle tube can be made to protrude from the distal end of the sheath by maximally moving the needle slider forward with respect to the sheath slider. In this state, the direction of the needle tip of the needle tube is adjusted by raising the sheath and the needle tube by activating the raising platform. 
     In the vicinity of the step portion provided in the needle tube, the diameter of the needle tube is larger at the proximal end side than at the step portion and therefore this is a region where it is difficult for the puncture needle to bend when the puncture needle is raised. According to this aspect, even when the needle tube is maximally moved forward, the puncture needle can be smoothly bent by the operation of the raising platform by arranging the step portion that is difficult to bend further toward the proximal end side than the proximal end of the raising platform. 
     In the above-described aspect, the puncture needle may be used together with an endoscope that includes an observational optical system, a channel, and an ultrasound sensor, and when a distal end of the sheath, which extends along the channel and is made to protrude from the distal end of the channel, is arranged inside an observational field of view of the observational optical system and the protrusion abuts the step portion, the needle tube and a tip portion of the protective tube may be located inside a detection range of the ultrasound sensor. 
     In the above-described aspect, a stroke range of the needle tube may be defined as being between a first position at which the needle tube protrudes from a distal end of the sheath and a second position at which the needle tube is retracted toward a proximal end side from the distal end of the sheath. 
     Another aspect of the present invention provides a method of using a guide wire, including: forming a through hole by puncturing a needle tube from the inside of a first lumen through a wall of the first lumen and a wall of a second lumen and arranging a needle tip of the needle tube inside the second lumen; moving a protective tube housed inside the needle tube forward along a longitudinal axis until a protrusion provided on at least part of an outer peripheral surface of the protective tube abuts a step portion provided inside the needle tube and thereby make a tip portion of the protective tube protrude from the needle tip of the needle tube; maintaining the protrusion in a state of pressing against the step portion from the proximal end side by moving forward the tube slider connected to the proximal end of the protective tube relative to the needle slider connected to the proximal end of the needle tube in a state where the protrusion has abutted the step portion; making a guide wire, which extends through the inside of the protective tube, protrude from a distal end of the protective tube into the inside of the second lumen; and positioning the guide wire from the first lumen to the second lumen by removing the needle tube and the protective tube from the through hole. 
     In the above-described aspect, the method may further include: inserting a tip portion of a stent deploying device into the second lumen along the positioned guide wire; dilating a tip portion of a stent deployed from the stent deploying device in the second lumen and dilating a proximal end portion of the stent in the first lumen; and connecting the wall of the first lumen and the wall of the second lumen. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  puncture needle 
               2  sheath 
               3  needle tube 
               4  protective tube 
               5  operation part body 
               6  slider sheath 
               7  needle slider 
               8  tube slider 
               10  needle tip 
               13  tubular parts (needle tip portion, needle base portion) 
               14  connection tube 
               15  guide wire 
               16  step portion 
               17  protrusion 
               18  locking portion 
               19  fixing mechanism 
               23  engagement portion 
               100  ultrasound endoscope (endoscope) 
               110  channel 
               120  observational optical system 
               130  raising platform