Abstract:
An assembly of cannula and endoscope and dissection tip facilitate surgical procedures at remote surgical site in tissue of a patient. Relative rotation of the cannula about the endoscope from clamped rotational fixation of the cannula and endoscope is made possible by flexing a resilient clamping segment, and such relative rotation promotes convenient positioning of an eccentric tissue-dissecting tip about a vessel being harvested from within tissue of a patient. Color tinting of the tip or color-tinted illumination of tissue at a remote surgical site enhances contrasting visualization through the tip via the endoscope among the tissue types encountered at the surgical site within a patient. A tool bridge or lateral support mounts to a more rigid component such as an endoscope that extends from the proximal end of a cannula to support a more flexible surgical instrument also extending from the proximal end of the cannula.

Description:
RELATED APPLICATION 
     The subject matter of this application relates to the subject matter disclosed in U.S. patent application Ser. No. 09/227,393, filed on Jan. 8, 1999 by Albert K. Chin, and now abandoned 
    
    
     FIELD OF THE INVENTION 
     This invention relates to endoscopic surgical instruments and more particularly to components thereof to facilitate assembly of surgical instruments in sturdy and releasable configuration for convenient and safe manipulation during surgical procedures. 
     BACKGROUND OF THE INVENTION 
     Contemporary endoscopic surgical instruments commonly include an elongated shaft or cannula having multiple lumens extending therethrough from end to end for slidably positioning various surgical instruments therein to be manually manipulated from a proximal end of the cannula in order to affect various surgical procedures at the distal end. An endoscopic viewing instrument is usually included within one of such lumens, and bipolar scissors, or the like, may be disposed in another lumen through the elongated cannula to perform a surgical procedure within a field of view of the endoscope at the distal end of the cannula. The elongated cannula may be relatively rigid to provide adequate support for the endoscope over its entire length, and a surgical instrument such as bipolar scissors may exhibit some flexibility attributable to sufficiently small cross sectional area to slidably fit within a lumen of the elongated cannula. Such surgical instruments of sufficiently small cross sectional area to slide within a lumen of the cannula may undesirably flex and bend along a segment of its length not supported within the cannula as the cannula and the instruments assembled therein are manipulated relative to a surgical site on a patient, with concomitant breakage of the unsupported instruments. 
     In addition, a number of endoscopic instruments may be assembled within the narrow confines of the lumens within the cannula to fan out over a wider region near the proximal end in order to facilitate convenient mechanical attachment of video cameras, electrical and fluid connections, and the like. The proximal end of the cannula may be disposed within a supporting housing and the array of instruments and components within the cannula may be arranged to emanate from the housing at various locations and angles in order to avoid undesirable physical interference among instruments assembled about the proximal end of the cannula. An endoscope and associated video camera may be locked into position within the housing for proper rotational orientation relative to the cannula and housing, but may require quick disconnect mechanisms to facilitate rotational reorientation as desired during a surgical procedure. The distal end of the cannula commonly includes a tissue-dissecting tip for bluntly dissecting tissue within a visual field through the tip provided by the endoscope. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention, an instrument bridge is supported on a sturdy component assembled at the proximal end of a cannula to provide auxiliary support for less sturdy instruments that emanate from the proximal end at various angles and in spaced relationships about the proximal end of the cannula. In one embodiment of the present invention, a support member attaches to the cylindrical body of an endoscope and its associated video camera or detector at a location where the endoscope extends from the housing at the proximal end of the cannula. The support member protrudes laterally from the elongated axis of the endoscope to provide additional support for an endoscopic instrument of thin cross section, such as bipolar scissors. Specifically, the instrument bridge includes resilient clamps at opposite ends to resiliently grasp at the base end of the support the generally cylindrical barrel of an endoscope and to resiliently grasp at the lateral end of the support the generally cylindrical shape and narrow cross section of a surgical instrument. In this way, the surgical instrument of relatively narrow cross section and high flexibility is supported on and displaced away from the endoscope and endoscope attachments of relatively greater and more rigid cross section. In addition, the housing at the proximal end of the cannula may selectively lock and unlock the endoscope and associated video camera for selective rotational orientations within the housing. The base end of the support may also rotate about the barrel of the endoscope. The distal end of the cannula includes a transparent tip of blunt, eccentric conical shape to provide a relatively distortion-free field of view for the endoscope to facilitate blunt dissection of tissue, for example, along the course of a saphenous vein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an endoscope emerging from a housing with an instrument support disposed thereon according to the present invention; 
     FIG. 2 is a perspective view of the embodiment of FIG. 1 showing a surgical instrument supported on the instrument support; 
     FIG. 3 is a front view of a housing and clamp for the instrument of FIG. 1; 
     FIG. 4 is a perspective view of a tissue-dissecting tip of one configuration according to the present invention; 
     FIG. 5 is an end view of the tip according to FIG. 4; and 
     FIG. 6 is a side sectional view of the tip of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is shown a perspective view of an elongated cannula  9  having a distal end (not shown) and a proximal end within housing  11 . One lumen within cannula  9  extends between distal and proximal ends thereof and receives an endoscope  13  therein that facilitates the viewing of a surgical procedure at the distal end from the proximal end that extends from the housing  11 . The endoscope  13  may include an eyepiece and an additional video detector  15  that attaches in axial alignment with the elongated optical axis of the endoscope  13 . The body of the endoscope  13  that extends from the housing includes a lighting port  17  that may also be used conveniently, as later described herein, for rotationally orienting the endoscope  13  relative to the cannula  9  and housing  11 . 
     In accordance with one embodiment of the present invention, an instrument bridge  19  includes a base clamp  21  attached to a lateral extension  23  that includes a smaller clamp or groove  25  at the distal end of the extension  23 . The structure  21 ,  23 ,  25  may be formed of a resilient polymeric material such as polycarbonate, or the like, to provide flexibility and resilient clamping force in the base clamp  21  when disposed about the generally cylindrical body of the endoscope  13 . The base clamp  21  may include a partial circumferential ring in excess of π radians and of about the same internal diameter as the cylindrical body of the endoscope  13  to promote snap-on clamping about the body of the endoscope  13 . The internal diameter of the partial circumferential ring may be selected to fit snugly about the body of the endoscope  13 , and to permit rotation of the instrument bridge  19  about the endoscope  13  as desired, for example, when rotating the cannula  9  about the endoscope  13 . 
     Thus, as illustrated in the perspective view of FIG. 2, an endoscopic surgical instrument  27  such as bipolar scissors having a small cross section over its elongated length for slidably and flexibly extending within a lumen of the cannula  9  between the ends thereof may ‘fan’ out or angle away from the elongated axis of the cannula at the proximal end thereof to be supported on the instrument bridge  19 . Specifically, the clamp or groove  25  in the outer end of the lateral extension  23  of the instrument bridge  19  may firmly support the surgical instrument  27  therein, for example, via resilient clamping force about the cross section of the surgical instrument  27 . The groove  25  may be formed in the resilient material of the instrument bridge  19  with smaller diameter than the diameter of the surgical instrument  27 , and with a substantially circular interior shape in excess of π radian circumference to promote snap clamping of the surgical instrument  27  in position, as shown. Of course, the circular interior shape of groove  25  may be of about the same diameter as the diameter of the surgical instrument  27  where desired to promote rotational and sliding movement thereof within the groove  25 . 
     As illustrated in FIGS. 1 and 2, an endoscope  13  may include an optical-fiber lighting channel for delivering illuminating light flux to the distal end of the endoscope within the cannula  9  from a light source (not shown) that attaches to the lighting port  17 . This port is commonly rigidly affixed to the cylindrical body of the endoscope  13 , for example, to contain input ends for optical fibers that channel light to the distal end of the endoscope. In one embodiment of the present invention, as illustrated in FIG. 3, the lighting port  17  may be clamped into lateral position relative to housing  29  by a hook-shaped clamping block  31  that may be selectively removed and attached to the housing  29  via hollow threaded fastener  33 . This fastener  33  thus permits a surgical instrument such as bipolar scissors to be slidably and rotationally positioned within the cannula  9 , and also facilitates selective attachment of the clamping block  31  to the housing  29 . In a preferred embodiment of the invention, the hook-shaped segment  35  of the clamping block  31  (one on each side of the clamping block  31  to facilitate one aligned and one oppositely-aligned clamping positions of the lighting port  17 ) is formed sufficiently thin of flexible material such as polyethylene or other resilient polymeric material to be deflected or flexed out of clamping engagement with the lighting port  17 . Specifically, the hook-shaped segment  35  is resilient and substantially semicircular with preferably less than π radian angular extent of the internal circumference about the diameter of the lighting port  17 , as shown in FIG.  3 . Thus, an endoscope disposed within the cannula and having a lighting port  17  disposed in clamped position relative to the housing  29  by the clamping block  31  may be conveniently twisted out of such clamped position without unscrewing the threaded fastener  33  by deflecting the resilient hook-shaped segment  35  out of locking engagement about the lighting port  17 . In this way, an endoscope within cannula  9  may be rotationally re-positioned relative to the cannula and the surgical instruments assembled therein in shorter time than is normally required to unscrew the threaded fastener  33  to release the clamping block  31  disposed about lighting port  17  of the endoscope. 
     Referring now to FIG. 4, there is shown a perspective view of a transparent tip  37  for attachment to the distal end of a cannula  9  to facilitate a surgical procedure such as blunt tissue dissection at a remote surgical site in a patient&#39;s body. Specifically, the transparent tip  37  includes a rearward section  38  that is disposed to attach (e.g., via press-fit, or adhesive attachment, or the like) to the distal end of a cannula, and includes a substantially conical forward section  39  that aligns with an endoscope within the cannula. The forward section  39  is displaced eccentrically from a cylindrical axis of the rearward section  38  to facilitate optical axial alignment with a field of view  41  of an endoscope  13  that is eccentrically oriented, as shown in the end view of FIG. 5, relative to an elongated central axis of a cannula attached to the rearward section  38  of the tip  37 . The tip  37  includes a transition section  43  intermediate the forward section  39  and the rearward section  38  that includes tapering side walls in smooth transition between the conical walls of the forward section  39  and the circumferential side walls of the rearward section  38 , as illustrated in side sectional view of FIG.  6 . The forward section  39 , intermediate section  43  and rearward section  38  of the tip  37  may be formed integrally and substantially symmetrically about a central vertical plane  45 , as shown in FIG. 4 and 5. The optical axis of the forward conical section  39  may thus be aligned with the field of view  41  of an endoscope disposed in eccentric orientation relative to the cylindrical axis of the rearward section  38  of the tip  37 , as illustrated in the end view of FIG.  5 . 
     In operation, the transparent tip  37  attached to the distal end of a cannula  9  protects an endoscope disposed therein from tissue and fluids and includes the transparent forward section of the tip  37  substantially optically aligned with the field of view of the endoscope. Thus, as the cannula is manipulated to perform a surgical procedure, for example, bluntly dissecting connective tissue from along a saphenous vein and around associated lateral branch vessels, the cannula  9  and attached tip  37  may be rotated about the elongated axis of the endoscope during tissue dissection along anterior and posterior segments of a saphenous vein to facilitate more complete dissection of connective tissue from the vein. And, such rotation of the cannula  9  about the endoscope may be conveniently accomplished by manually supplying rotational torque to the housing  29  relative to the endoscope  13  sufficiently to deflect the hook-shaped segment  35 , as shown in FIG. 3, away from clamping engagement about the lighting port  17  of the endoscope  13 . With the tip  37  removed from the distal end of the cannula  9 , another lumen  48  of the cannula may be used to position therein a surgical instrument such as bipolar scissors  27  to facilitate excision and cauterization of lateral branch vessels encountered along the length of the saphenous vein. 
     The transparent tip  37  includes a blunt, slightly rounded distal end  47  of approximately 0.040″ radius for bluntly dissecting tissue away from a saphenous vein and associated lateral branch vessels, and such tip may be formed of a bioinert, transparent material such as polycarbonate, glass, or the like, with conical walls of substantially uniform thickness in the forward section  39 . Such conical shape in alignment with the optical axis of the endoscope reduces visual distortion in the field of view  41 . However, the forward section  39  and intermediate section  43  may be formed in alternative configurations such as spoon shape or duck-bill shape or elliptical shape, or the like, to optimize the optical characteristics. The forward section  39  may be color tinted, at least within the field of view  41  of an endoscope to promote enhanced visual contrast between walls of a saphenous vein, connective tissue and blood encountered at a remote surgical site within a patient. It has been discovered that such color tinting at least of the forward section  39  within the spectral color range between yellow and blue tints enhances such visual contrast, with blue tint providing more effective visual contrast. 
     Therefore, the apparatus of the present invention promotes versatile and sturdy configurations of surgical instruments assembled within a cannula for performing surgical procedures at remote sites in tissue within a patient. An eccentric configuration of a blunt tip attached to the distal end of the cannula aligns with the optical axis of an endoscope that is positioned eccentrically therein to facilitate rotational manipulation of the cannula and attached tip about the endoscope. Also, the tissue-penetrating distal tip of small diameter aligned with an endoscope in one lumen significantly reduces the force required to dissect tissue away from the saphenous vein. Additionally, such tip of small diameter improves maneuverability around lateral branch vessels and along the saphenous vein in the lower leg within a thinner layer of subcutaneous fat. The transition cone between sections  38  and  39  transitions from these benefits of a small cone to the larger diameter of a two-lumen cannula without significantly diminishing the benefits of a small-diameter blunt dissection tip. Clamped fixation of the endoscope within a housing attached to the proximal end of the cannula may be conveniently overridden by deflecting a flexible hook-shaped segment of the clamp disposed about a lighting port of the endoscope in response to rotational torque applied to the housing relative to the endoscope. Color tinting of the transparent, tissue-dissecting tip serves as a rigid lens that promotes enhanced visual contrasts between tissue types encountered at remote surgical sites within a cavity in tissue of a patient. Such color tinted tip reduces glare reflected back from tissue and fluids and filters wavelengths of light transmitted back through the endoscope. A video detector attached to the proximal end of an endoscope may, with associated electronics of conventional design, provide further enhanced visual contrasts using ‘white balance’ electronic filtering to render the color tinting apparently clear while providing the desired visual contrasts and effects. Alternatively, a remote surgical site may be visualized through an endoscope as illuminated by color-tinted light supplied to the remote surgical site for similar benefits of enhanced contrasts between types of tissues encountered at the remote surgical site within a cavity in tissue of a patient.