ENDOSCOPE INSTRUMENT HAVING REDUCED BACKLASH DURING INSERTION

Abstract: An endoscopic instrument has a portion having an outer surface with a non-circular cross-sectional shape. The non-circular cross-sectional shape may be provided to the instrument by providing peripheral projections or fins along the length of the portion or by providing the periphery of the portion with a polygonal shape. Where fins are used, the fins are preferably quite small and only have a minimal effect on the fluid flow cross sectional area between the interior of the working channel and the endoscopic instrument. The resulting instrument has significantly reduced backlash while maintaining adequate fluid flow in the working channel. According to a second embodiment of the invention, a portion of the interior of the working channel of the endoscope has an interior surface having a non-circular cross-sectional shape by the inclusion of a plurality of radially spaced and inwardly directed ribs or by being polygonally shaped. The resulting endoscope reduces the backlash of an endoscopic instrument inserted therein while maintaining adequate fluid flow in the working channel.

Description: ENDOSCOPE INSTRUMENT HAVING REDUCED BACKLASH DURING INSERTION Background of the Invention 1. Field of the Invention This invention relates broadly to surgical instruments. More particularly, this invention relates to an endoscope and endoscopic surgical instruments adapted to be extended into a channel of the endoscope. 2. State of the Art At the present time there are many instruments made for use in endoscopic medical procedures. Typically, endoscopic instruments are long and flexible cylindrically tubular devices with manually operated handles at their proximal ends and tissue-manipulative cutting, grasping, injecting, or cautery components at their distal ends. Such instruments are introduced into a flexible endoscope which is inserted into the patient through a natural or surgically-created opening. The endoscope includes an elongate portion defining several lumens therethrough and a proximal handle for directing the elongate portion. At least one lumen is provided with an optical imaging system, e.g., a scope, and several lumina or "working channels" are typically provided for extending endoscopic instruments therethrough. The working channel of the endoscope typically consists of a PTFE-lined cylindrical tube passing from the proximal (handle) end of the endoscope to its distal (working) end. Working channels are typically 2 to 4 millimeters in inside diameter. During the medical procedure, the doctor passes one or more endoscopic instruments through the working channels in order to manipulate the tissue being visualized by the optical system of the endoscope. Usually the doctor must repeatedly manipulate the distal end of the instrument by manually pushing and pulling on the proximal portion of the tubular shaft of the endoscopic instrument near where the shaft enters the handle of the endoscope. The view through an endoscope is highly magnified when seen on the video monitors typically used for these procedures; a field of view that may be a few millimeters across would be enlarged to several inches on the video screen. Accordingly, the instrument must be moved very precisely in very small increments in order to approximate and treat the tissue being visualized. In fact, the doctor must position the distal tip of the endoscopic instrument within a fraction of a millimeter of the desired location in order to achieve desired results. However, because of friction and backlash in the way the instrument passes through the endoscope, achieving this level of accuracy is difficult. For example, an endoscope several feet long may be positioned in the colon of a patient with the distal end of the endoscope tightly reflexed to visualize a particular area of the ascending colon. In such a position, the endoscope is bent into a very sinuous shape in multiple planes. Since the outside diameter of the endoscopic instrument is significantly smaller (e.g., 2.2 mm) than the inside diameter of the working channel (e.g., 3.2 mm), a large clearance space exists between the instrument and the channel. When the instrument is pulled back, the tension on the instrument causes the instrument to be pulled taught and the instrument naturally assumes the shortest path through the channel. When the instrument is pushed forward, friction causes it to assume the longest path through the channel (that is, the shaft of the instrument must "fill" the working channel before the distal end of the instrument begins to move). As a result, quite a bit of backlash (lost motion) is experienced by the doctor when the doctor tries to manipulate the distal end of the instrument. If it is necessary to pull the tip back a bit, the backlash must first be pulled out before the distal end can be retracted. If the doctor pulls the instrument back a little too far, the doctor must then push it several millimeters forward before there is any motion at all at the distal end. During this manipulation, the endoscopic instrument alternately assumes the longest-path and shortest-path positions within the working channel of the endoscope. If this backlash can be reduced or eliminated, the manipulation of the distal end of the endoscopic instrument can be made much easier and more positive, and the doctor can achieve his desired positioning more rapidly. However, this is not a simple problem to overcome for several reasons. While the backlash situation described above can be reduced or substantially eliminated if the clearance between the outside of the endoscopic instrument and the inside of the working channel of the endoscope can be reduced, this is not a practical solution. It is often necessary to inject fluid (or to operate suction) through the annular space between these two structures. If the instrument shaft were to substantially fill up the space within the working channel, the backlash would be reduced, but there would be greatly reduced ability to conduct fluid through the working channel around the instrument. In fact, because of the nature of fluid flow, as the aspect ratio of the annular clearance space (the ratio of the thickness of the fluid channel to its circumferential length) becomes small, the impedance to fluid flow grows disproportionately to the reduction in cross-sectional area of the fluid passage. In addition, as the diameter of the shaft approaches the inside diameter of the working channel, the area of contact between the instrument and the working channel becomes larger, particularly since the working channel is usually made of a relatively soft material, PTFE. This increase in contact area between these parts results in an increase in frictional drag on the instrument when the doctor attempts to move it through the channel. Summary of the Invention It is therefore an object of the invention to provide an endoscopic system with little or no backlash between the endoscope and the endoscopic instrument. It is also an object of the invention to provide an endoscopic system which reduces the backlash between an endoscopic instrument in a working channel of an endoscope, while maintaining open area therebetween for permitting fluid flow. In accord with these objects, which will be discussed in detail below, an endoscopic system is provided where either a portion of the endoscopic instrument or a portion of the working channel is provided with a non-circular cross-section. Generally, an endoscopic instrument includes an elongate flexible tubular member having proximal and distal ends, a control member having proximal and distal ends and extending through the tubular member, an end effector assembly coupled to the distal ends of the tubular member and the control member, and a handle means for moving the control member relative to the tubular member to operate the end effector assembly. According to a first embodiment of the invention, the distal end of the elongate flexible tubular member of the endoscopic instrument has an outer surface having a non-circular cross-sectional shape. The non-circular cross-sectional shape may be provided to the portion of the tubular member by radially spacing a plurality of fins or other projections about the peripheral (exterior) of the portion, or by providing the portion with a polygonal cross-sectional shape. Where fins are provided, the fins can be quite small and will only have a minimal effect on the fluid-flow cross-sectional area between the working channel and the endoscopic instrument. Thus, the resulting endoscopic instrument will have significantly reduced backlash while maintaining adequate fluid flow in the working channel. In addition, the fins or corners of the polygonal shape provide few and relatively small contact points so that the endoscopic instrument may be readily advanced through the lumen (working channel) of an endoscope. According to a second embodiment of the invention, an endoscope is provided having a proximal handle, and elongate flexible distal portion having an imaging channel provided with an imaging system and a working channel having an interior surface and adapted to receive an endoscopic instrument therethrough. The working channel along its length has a preferably substantial portion at which the working channel has a non-circular cross-sectional shape. The non-circular cross-sectional shape can be provided to the working channel by providing the interior surface of the working channel with a plurality of radially spaced and inwardly directed ribs or other projections or by providing the interior surface of the working channel with a polygonal shape. The ribs can be quite small and will only have a minimal effect on the fluid flow cross sectional area between the working channel and the endoscopic instrument. Therefore, the resulting endoscope will reduce the backlash of an endoscopic instrument inserted therein while maintaining adequate fluid flow in the working channel. Additionally, the endoscopic instrument can be readily advanced through the working channel, as there will be few and relatively small contact points between the two. Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. Brief Description of the Drawings Figure 1 is a longitudinal cross sectional view of an endoscopic instrument according to the invention; Figure 2a is an enlarged cross-section across line 2-2 in Figure 1 according to a first embodiment of the invention; Figure 2b is an enlarged cross-section across line 2-2 in Figure 1 according to an alternative first embodiment of the invention; Figure 3 is a side elevation of an endoscope according to the invention shown provided with an endoscopic instrument according to the invention; and Figure 4 is an enlarged cross-section across line 4-4 in Figure 3, illustrating several working channel-endoscopic instrument systems according to the invention. Detailed Description of the Preferred Embodiments Turning now to Figure 1 , an endoscopic instrument 10 for insertion through a working channel of an endoscope is shown. According to a first embodiment of the invention, the endoscopic instrument 10 includes an actuation handle 12, a tubular coil 14, a jacket 16 provided about at least a distal portion 18 of the coil 14, an end effector assembly 20, e.g., a biopsy forceps, and a control wire 22. The actuation handle 12 typically includes a stationary member 26 and a displaceable spool 28. The stationary member 26 includes a distal throughbore 30, a central slot 32, and a proximal thumb ring 34. The displaceable spool 28 is slidably disposed on the stationary member 26 and has a cross member 36 which passes through the slot 32. The proximal end of the control wire 22 is coupled to the spool 28. Operation of the actuation handle 12 is described fully in U.S. Pat. No. 5,228,451 to Bales, which is hereby incorporated by reference herein in its entirety. In brief, longitudinal movement of the spool 28 within the slot 32 results in operation of the end effector assembly 18; i.e., the end effector assembly moves between open and closed positions. Referring now to Figure 1 and 2a, in accord with the first embodiment of the invention, the jacket 16 is a low friction coating or sheath, preferably made from PTFE, extending over at least a distal portion of the coil 14. The jacket 16 may be extruded over the portion of the coil, or may be provided as an attachment capable of being provided over an assembled endoscopic instrument. For example, the jacket may be a tubular member having a longitudinal slit. The jacket 16 defines several, e.g., five, longitudinal fins 30 radially spaced about the coil. By way of example, and not by limitation, for an endoscopic instrument intended to be inserted into an endoscope having a working channel of 3.2 mm inside diameter, the jacket 16 is preferably a cylinder 2.2 millimeters in diameter with thin fins (or lands) having a thickness of approximately 0.1 mm and extending approximately 0.4 mm out from the coil surface. Such a construction would almost completely fill the diameter of the working channel of the endoscope (i.e., the radial dimension of the jacket, from the center of the coil 14 out to the end of a fin 30, is nearly equal to the radius of the working channel), substantially reducing the motion backlash. However, since the fins 30 are quite thin, only a small amount of the fluid-flow cross sectional area would be sacrificed. Additionally, the number of the contact points and surface area of contact points between the fins and the interior of the working channel is substantially minimal. It is also preferable that the fins extend along only a distal portion of the endoscopic instrument rather than along the entire length of the endoscopic instrument. If the fins 30 were to extend to the most proximal portion of the coil 14, it would be difficult to effect a fluid seal against the shaft of the instrument where the coil enters the endoscope handle. Such a seal is needed if fluid is to be injected through the working channel. Since the majority of the flexing of the endoscope in an endoscopic procedure takes place at the distal portion, where the endoscope is situated inside the patient, the majority of motion backlash results from the looseness of the instrument in the distal portion of the endoscope. Accordingly, it is preferable for the fins 30 to be placed on only the corresponding distal portion 18 of the endoscopic instrument 10 (for example, on the distal 150 cm of a 240 cm instrument) while leaving the proximal portion (i.e., 90 cm) a smooth cylinder. Such an endoscopic instrument would then have greatly reduced motion backlash when manipulated by the physician, and it would allow substantially unimpeded fluid flow through the working channel of the endoscope while providing an easily sealed-upon surface where the instrument exits the endoscope handle. Turning now to Figure 2b, according to an alternate first embodiment of the invention, the jacket 16b has a non-circular cross-sectional shape over the coil 14 such that the cross-sectional shape is generally polygonal. For example, the jacket 16b may have a pentagonal shape, as shown. By way of example, and not by limitation, for an endoscopic instrument intended to be inserted into an endoscope having a working channel of 3.2 mm inside diameter, the corners 30b of the polygon preferably extend approximately 0.4 mm from the coil surface. Such a construction substantially completely fills the diameter of the working channel of the endoscope, substantially reducing the motion backlash, yet only contacts the working channel at the corners 30b. In addition, space is provided between the sides of the jacket and the working channel for fluid-flow. Referring now to Figures 3 and 4, an endoscope 110 according to a second embodiment of the invention is shown. The endoscope 110 includes an elongate tubular portion 1 12 and a proximal handle portion 114 adapted to manipulate and direct the distal end of the tubular portion 112. The tubular portion 112 has a plurality of lumens, with one lumen 142 provided for receiving an optical scope or camera device 144 (which may be built therein), several lumen 146, 148, 150, 152 provided for receiving control wires 154, 156, 158, 160 extending from the handle portion 114 through the tubular portion 1 12, and at least one, and preferably several working channels 162, 164, 166, 168 for receiving endoscopic instruments 170 therethrough. For example, endoscopic instruments 10, 10b according to the first embodiment of the invention (as shown in Figs. 2a, and 2b, respectively) may be provided in working channels 166, 168. The working channels have proximal openings in the handle portion 114. Other lumens 172, 174 may be provided for other purposes. Endoscopes are described in general in U.S. Patent No. 5,179,935 to Miyagi which is hereby incorporated by reference herein in its entirety. According to the second embodiment of the invention, a portion of at least one of the working channels 162 is provided with a non-circular cross-sectional shape. The non-circular cross-sectional shape may be molded into the working channel or more preferably is provided by a low friction, e.g, PTFE, insert 180 preferably fixed within a distal portion 118 of the working channel 162. The insert 180 includes a plurality of radially spaced and radially inwardly directed longitudinal ribs 182. The ribs 182 can be quite small. For example, the ribs 182 may be approximately 0.1 mm thick and have a radial length of approximately 0.5 mm. Therefore, the ribs would have a minimal effect on the fluid flow cross sectional area between the working channel and the endoscopic instrument, and also provide relatively small contact points between the working channel and the endoscopic instrument. According to an alternate second embodiment of the invention, a working channel 164 is provided with a polygonal cross-sectional shape. The polygonal cross- sectional shape may be provided to the working channel 164 via an insert 182 or may be molded integrally into the working channel. In each of the alternate embodiments, the working channel is adapted to provide reduced backlash, while maintaining adequate fluid flow in the working channel around the endoscopic instrument, and minimal contact between the endoscopic instrument and the working channel. In each alternate embodiment, the non-circular cross-sectional shape of the working channel may extend the entire length of the channel or a portion thereof. There have been described and illustrated herein several embodiments of an endoscope and endoscopic instrument system having reduced backlash when moving the endoscopic instrument within the working channel of the endoscope. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while a particular biopsy forceps endoscopic instrument has been disclosed, it will be appreciated that endoscopic instruments having other end effectors, e.g., scissors, punches, needles, etc., can be provided with the non-circular cross-section of the invention as well. Furthermore, while a PTFE has been disclosed for the jacket of the instruments and insert for the endoscope, other low friction materials can be used as well. Also, while a particular number of fins and ribs have been disclosed, it will be appreciated that other numbers of fins and ribs can be used. Alternatively, one or spiral fins or ribs can be provided. Furthermore, projections other than fins can be used. Moreover, other polygonal shapes may be used for the jacket over the coil and the endoscope insert. Also, the coil and/or jacket may be substituted with another tubular member having a non-circular cross-section. For example, the tubular member may be extruded with a polygonal shape or with fins. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed.

Claims: What is claimed is: 1. An endoscopic instrument system, comprising: a) an endoscope having an elongate flexible distal portion and a proximal handle portion for manipulating said distal portion, said distal portion including an optics channel which receives an imaging means and a working channel having an interior surface and adapted to receive an endoscopic instrument therethrough; and b) an endoscopic instrument including an elongate flexible tubular member having proximal and distal ends and an outer surface, a control member having proximal and distal ends and extending through said tubular member, an end effector assembly coupled to said distal ends of said tubular member and said control member, and a handle means for moving said control member relative to said tubular member to operate said end effector assembly, wherein at least one of said inner surface of said working channel and said outer surface of said tubular member is provided with a non-circular cross-sectional shape along a portion thereof adapted to reduce backlash when moving said endoscopic instrument relative to said working channel of said endoscope. 2. An endoscopic instrument system according to claim 1, wherein: said non-circular cross-sectional shape is a polygonal shape. 3. An endoscopic instrument system according to claim 1 , wherein; said non-circular cross-sectional shape includes a plurality radial projections. 4. An endoscopic instrument system according to claim 1, wherein: said portion is a portion along said tubular member on which a jacket is provided which includes a plurality of fins over said tubular member. 5. An endoscopic instrument system according to claim 1, wherein: said portion is a portion of said working channel which is provided with an insert having said non-circular cross-sectional shape. 6. An endoscopic instrument system according to claim 1 , wherein: said portion is a portion of said working channel of said endoscope, and said portion includes a plurality of substantially radially inwardly directed ribs. 7. An endoscopic instrument system according to claim 1 , wherein: said proximal end of said tubular member is substantially circular in cross- sectional shape. 8. An endoscopic instrument for insertion through an endoscope having a working channel provided with a circular cross-sectional shape, said endoscopic instrument comprising: a) an elongate flexible tubular member having proximal and distal ends and an outer surface, said outer surface having a portion having a non-circular cross- sectional shape; b) a control member having proximal and distal ends and extending through said tubular member; c) an end effector assembly coupled to said distal ends of said tubular member and said control member; and d) means for moving said control member relative to said tubular member to operate said end effector assembly. 9. An endoscopic instrument according to claim 8, wherein: said portion of said outer surface provided with said non-circular cross- sectional shape includes a radial dimension which is nearly equal to a radius of the working channel such that when said endoscopic instrument is moved longitudinally relative to the working channel of the endoscope, backlash is reduced. 10. An endoscopic instrument according to claim 8, wherein; said non-circular cross-sectional shape is defined by a jacket provided over said tubular member, said jacket including a plurality of longitudinal fins. 11. An endoscopic instrument according to claim 10, wherein: said fins are radially spaced and directed radially outward. 12. An endoscopic instrument according to claim 10, wherein: said fins are approximately 0.1 mm thick. 13. An endoscopic instrument according to claim 10, wherein: said fins extend outward approximately 0.4 mm from a surface of said tubular member. 14. An endoscopic instrument according to claim 8, wherein: said non-circular cross-sectional shape is defined by a plurality of longitudinal fins extending radially outward from said tubular member. 15. An endoscopic instrument according to claim 8, wherein: said non-circular cross-sectional shape is defined by a jacket provided over said tubular member, said jacket having a substantially polygonal shape. 16. An endoscopic instrument according to claim 8, wherein: said portion of said outer surface of said tubular member which has said non- circular cross-sectional shape is at least a distal half of a length of said tubular member. 17. An endoscopic instrument according to claim 8, wherein: said portion of said outer surface of said tubular member which has said non- circular cross-sectional shape is defined by a low friction jacket provided over said portion, said low friction jacket having said non-circular cross-sectional shape. 18. An endoscopic instrument according to claim 8, wherein: said proximal end of said tubular member is substantially circular in cross- sectional shape. 19. An endoscopic instrument according to claim 8, wherein: said tubular member is a coil. 20. An endoscope for receiving an endoscopic instrument therein, the endoscopic instrument including a distal tubular portion having a circular cross- sectional shape and having an outer diameter, said endoscope comprising: a) an elongate flexible distal portion having an optics channel provided with an imaging means and a working channel having an interior surface and adapted to receive the endoscopic instrument therethrough, said working channel having a portion at which said interior surface has a non-circular cross-sectional shape; and b) a proximal handle portion adapted to manipulate said distal portion. 21. An endoscope according to claim 20, wherein: said working channel of said endoscope includes an insert which defines said portion at which said interior surface of said working channel has said non-circular cross-sectional shape. 22. An endoscope according to claim 20, wherein: said portion at which said interior surface of said working channel has said non-circular cross-sectional shape has a polygonal shape. 23. An endoscope according to claim 20, wherein: said portion at which said interior surface of said working channel has said non-circular cross-sectional shape has a plurality of radially inwardly directed longitudinal projections.

Inventors: SMITH KEVIN W, SMITH, KEVIN, W.
Applicants: SCIMED LIFE SYSTEMS INC, SCIMED LIFE SYSTEMS, INC.
Application year: 2000
Main classification: A61B1
IPC codes: A61B1, G02B23