Patent Publication Number: US-2005137585-A1

Title: Back loading endoscopic instruments

Description:
This application claims the benefit of the filing date under 35 U.S.C. § 119(e) of Provisional U.S. Patent Application Ser. No. 60/532,397, filed on Dec. 23, 2003, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION  
      The field of the invention is that of medical and surgical instruments, and in particular, medical and surgical instruments intended primarily for minimally-invasive procedures. These instruments typically have a small diameter for entering body spaces or orifices of limited size.  
     BACKGROUND  
      One trend in modern surgery is the trend toward minimally-invasive procedures, in which laparoscopic or endoscopic procedures are used. These procedures tend to be less invasive to the patient, using a body orifice or a puncture into a body cavity or a natural existing space as an entry point for a medical device. Examples of entry points include a component of the urinary tract or the gastrointestinal system. These procedures are used in order to avoid major incisions for surgical access, accomplishing the medical procedure in less time with less risk to the patient, and with reduced patient convalescence.  
      Minimally invasive procedures thus provide benefits to the patient, in the sense that the procedures may be accomplished more quickly and more economically, and with less discomfort and less overall invasion of the body when compared to traditional open surgical techniques. Minimally-invasive procedures are not without their problems, however. One significant problem is that body orifices tend to be small, and thus minimally invasive surgical procedures may be difficult to accomplish due to the very small access provided. For example, when entering the urinary tract, space in the urethra and the ureter is very limited, since these passages are only several millimeters in diameter. As a result, the majority of minimally invasive procedures are performed with an endoscope, or with instruments bearing some resemblance to an endoscope, such as a hysteroscope or a ureteroscope. These instruments typically have a working channel that limits instruments or surgical tools to a diameter of about 3 Fr (1 mm).  
      The size of the surgical tools is limited because they are routed to the operating site through the working channel of the endoscope or similar instrument. The working channel may vary from about 2.6 Fr to about 3.4 Fr, about 1 mm in diameter. To date, the size of the surgical tools that can be used with endoscopic equipment has been limited because the instrumentation is routed to the operating site through the working channel of the endoscope or similar instrument. These very small instruments can be challenging to design and build. Using these instruments is also difficult because the small size of the end-effector is not always effective to accomplish surgical goals, which may include grasping tissues, taking biopsy samples, or moving tissues. Engineering and materials limitations become very evident when instruments of such small diameters are created.  
      For the majority of minimally invasive procedures, the user accesses the desired site, perhaps with a wire guide, and then uses one or more wire guides, and perhaps a sheath, for greater access. Because the working instruments are deployed via the working channel of the endoscope being used to access the target site, it is frequently necessary to make repeated trips to the target location to achieve the desired end-point of the operation, such as the grasping of structures, biopsy of tissues, or manipulation of either tissues or structures. A tremendous improvement in current technology for minimally invasive surgery would be instruments or end-effectors which are not limited to the diameter of a working channel of existing endoscopes. What is needed is a surgical instrument which allows more freedom to operate while adhering to the principles of minimally-invasive surgery.  
     BRIEF SUMMARY  
      There are many aspects and embodiments of the invention. One aspect of the invention is a back-loading medical instrument comprising a flexible hollow tube, a control rod within the hollow tube, and a distal functional portion. The functional portion is attached to at least one of the flexible hollow tube and the control rod, and has a cross-sectional area larger than the tube and larger than a working channel of a therapeutic or diagnostic medical device for use with the back-loading medical instrument. This embodiment allows for large laparoscopic end-effectors deployed through a single, slightly larger incision, to be attached in the body cavity to smaller diameter control rods. Such smaller diameter rods may be passed through diminutive access sites for what may be termed very-minimally invasive access.  
      Another aspect of the invention is a back loading instrument for an endoscope. The instrument comprises a distal portion including a forceps, a control portion operatively connected to the forceps, and a proximal portion for insertion into a working channel of an endoscope. The cross-sectional area of the forceps is greater than a cross-sectional area of a working channel of the endoscope.  
      Another aspect of the invention is a back loading endoscopic biopsy instrument. The instrument comprises a flexible hollow member having a proximal end and a distal end, and a flexible inner member having a proximal end and a distal end and extending through said hollow outer member. The instrument also comprises a jaw assembly having a pair of jaws extending distally, the jaw assembly coupled to at least one of the hollow outer member and the flexible control member. In this embodiment, a circumference of the outer jaws in a closed state is greater than a circumference of a working channel of the endoscope.  
      Another aspect of the invention is a method of making a back loading endoscopic instrument. The method comprises forming an openable functional portion, a flexible inner member, and a hollow tubular member, and assembling the hollow tubular member outside the flexible inner member. The method also comprises attaching the functional portion to at least one of the flexible inner member and the hollow tubular member. In this embodiment, an outer periphery of the openable functional portion is greater than an outer periphery of a working channel of an endoscope when the functional portion is in a closed state.  
      There are many ways to practice the present invention, a few of which are shown in the following drawings and specification. The embodiments are not meant to limit the invention, but rather to describe and illustrate a few of the many ways that the present invention may be used. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of an embodiment of a back-loading biopsy grasper mounted on a coil;  
       FIG. 2  is a closer view of a back loading endoscopic forceps showing the relationship with a working channel of an endoscope;  
       FIG. 3  is an embodiment of a back loading instrument with biopsy cups;  
       FIG. 4  is another embodiment of a back loading instrument, an angled forceps;  
       FIG. 5  depicts a back loading instrument with hot biopsy forceps;  
       FIG. 6  depicts a back-loading instrument with a sharp cutting tool and a spike;  
       FIG. 7  depicts a back loading forceps preferably deployed by retracting a sheath rather than actuating a distal control mechanism; and  
       FIGS. 8-10  depict additional embodiments of the back-loading instrument.  
       FIGS. 11-14  depict handles suitable for use in controlling the back-loading endoscopic devices. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS  
      Several embodiments of the back-loading instruments are presented and explained in this portion.  FIG. 1  depicts a back-loading biopsy grasper  10  for back loading into an endoscope  19 . Grasper  10  includes a distal portion  11  and a proximal portion  12 , with a grasper control portion  13  and upper and lower jaws  14 . Control portion  13  may include pins, levers and connections for a control cable  15  and a flexible outer sheath  16  for the back loading biopsy grasper. Jaws  14  preferably do not extend more than about 1 cm from an endoscope or other diagnostic or therapeutic instrument with which the back-loading grasper is used.  
      The distal portion  11  may be as large as needed, but the distal portion will still have to be inserted into the patient, for example, through an access sheath into which the distal portion will fit. It is also preferred that the diameter of distal portion  11  not be so large as to interfere with light from the scope that is transmitted to the site of interest, or from light from the site reflected back into the scope for the physician or other health professional to see.  
      The outer sheath  16  is desirably not more than about 2.6 Fr, and may be as large as 3.4 Fr, in diameter, so that the proximal portion  12  of the back-loading grasper may be inserted into the distal end of a diagnostic or therapeutic instrument. The medical device may include an endoscope, a colonoscope, a bronchoscope, or a ureteroscope. In some embodiments, the outer sheath interacts with the forceps or other functional portion on the distal end of the endoscopic instrument. These functional portions may include any forceps, grasper, incisor, extractor, cutting instrument, or end-effector that may be desired. The larger end-effectors may have additional capabilities, such as a biopsy forceps for taking tissue specimens that also has an active electrosurgical component for coagulation ( a “hot” biopsy forceps).  
      The functional portions, or end-effectors, may be made by any convenient manufacturing operations. They may be made by stamping or blanking from sheet metal and forming into the desired shapes, as in a process using progressive dies. For smaller volumes, they may be machined as desired and the movable jaws formed on an axis supplied by a rivet or other fastener. Alternately, the jaws may be formed from tubing by an electrical discharge machining (EDM) process, with or without additional forming. Forceps, extractors, incisors, or other desired functional distal portions may also be formed by machining stainless steel plate or other desired material. Components for end effectors may also be cast, and like other processes, the parts assembled, if necessary, into an articulable end effector.  
      The control cable  15  may be made from any convenient, flexible and strong material, such as stainless steel or a shape-memory alloy, such as Nitinol®. The cable should not elongate in use and may be made of a single wire or may be a bundle of smaller wires. The sheath  16  is ideally also strong and very flexible. It may be made from a polymer, such as a fluoropolymer or a polyimide-type polymer. Other polymers may also be used, such as PEEK (polyetheretherketone). The cable can be of very small diameter, allowing for minimal obstruction of the working channel while accomplishing deployment of the end-effector, i.e., opening and closing the jaws of an instrument.  
      Distal portion  11  may be attached to a flexible coiled wire  17  surrounded by the sheath, the coiled wire extending through to the proximal end for connection to endoscope  19 . The outer diameter of the sheath, as mentioned above, preferably is about 2.6 to about 3.4 Fr, or about 1 mm, in diameter. The control cable  15  inside the coil should not bind or chafe on the coil. When back-loading the control cable, coil, and sheath into the endoscope or other diagnostic of therapeutic instrument, the proximal ends should be shielded, perhaps by a soft cap or soft plastic end  18 , so that the ends do not scratch or damage the endoscope.  
       FIG. 2  depicts a distal end  20  of an endoscope which may be used with any of the back-loading instruments of the present invention. The endoscope may include a working channel  21 , a lens  22 , and one or more fiberoptic light sources  23 . The proximal or back end  28  of the back-loading endoscopic instrument  24  is inserted into the working channel  21  on the distal end  20  of the endoscope. As discussed above, there are many types of endoscopic instruments which may be designed for back loading. The embodiment in  FIG. 2  includes a grasper  27  controlled by an outer sheath  25  and a control rod  26 .  
      In use, the surgeon may maneuver the endoscope to the area of interest within a patient. The endoscope includes a forceps or other tool on the distal end, along with a fiberoptic light source and lens, and a camera, or optical transmitter (not shown), to generate and transmit images through the endoscope. A forceps is an endoscopic tool used for grasping a structure, such as tissue, for maneuvering or for removal. Using the images from the endoscope, the surgeon maneuvers the endoscope and then the forceps to the desired position. Typically, a biopsy sample is then acquired and removed from the patient. Using the back-loading endoscopic tool, a much larger sample, more than the usual microscopic size, may be taken. This enables the pathologist or laboratory technician to more easily analyze the sample. A prognosis or a treatment may then be decided more easily.  
       FIG. 3  depicts another embodiment of a back-loading endoscopic cup. The back loading endoscopic cup  30  includes a hollow urethane tube and a control wire  37  for controlling the cup. Urethane is tough and strong, as well as flexible, and may be formulated to be smooth and with a low coefficient of friction against control wire  37 . The distal portion  35 , which may be metallic, is mounted to tube  38  and includes first and second jaws  31 ,  32 , control linkages  33 ,  34  for the jaws, and a control portion  35 . The control portion and jaw portions have a larger diameter than that of tube  38 . Tube  38  is preferably about 1 mm outer diameter, preferably about 2.4 to 2.6 Fr. The control rod may preferably be stainless steel or Nitinol®. Tube  38  may be coated with a thin, smooth, lubricious coating  39 , such as Teflon® or other fluoropolymer, or other suitable smooth coating. A very thin film, such as from a fluoropolymer or PEEK, may be used instead.  
      The back loading instruments seen so far have largely been straight-forward, i.e., the deployed instruments, the cup or graspers or forceps, are in line with the endoscope and the sheath.  FIG. 4  depicts an embodiment in which the back-loading instrument, and the coil and control cable, may be at an angle to the advance of the endoscopic instrument.  FIG. 4  depicts an angle forceps  40 , with first and second jaws  42 ,  43 , control portions  44 ,  45 , and a spike  46 . The angle forceps  40  is angled at about 45° to the coil  41  and control cable  48 . The sheath and control cable may be made from shape memory alloys, such as Nitinol®.  
      Nitinol® forming techniques are used so that the control cable and coil will have a tendency to assume the shape in which they were trained. As is well known to those skilled in shape memory alloys, the sheath and the control cable may be formed in the desired shape, perhaps with forms or tools. They are formed at or below room temperature, and are then heat treated at a high temperature, typically from about 400° C. to about 500° C. Thus, the natural tendency of the angled forceps is to assume a position at about a 45° angle to the sheath and the control rod. This particular forceps allows the surgeon one more degree of freedom in diagnosing a patient or in conducting a biopsy, i.e. obtaining a desired sample for pathology.  
      Another embodiment is a hot biopsy forceps. The hot biopsy forceps is similar in concept to other back-loading instruments, but the forceps include heating elements integral to the forceps. Using the heating elements, the jaws of the forceps can be quickly heated to help free a biopsy sample or to coagulate small bleeding sites related or not related to the biopsy. When the sample has been obtained, the electric power may be turned off, and the jaws will quickly cool off to avoid any trauma to other nearby tissues.  
      The hot biopsy forceps  50  is depicted in  FIG. 5 . The hot biopsy forceps includes a control rod  51 , one or more wires  52  to conduct electricity, and a coil  53 . The forceps has a control portion  54  at the distal end, connected to coil  53  and including linkages  55  for control rod  54  to jaws  56 . The jaws  56  may include resistance heating elements  57  connected by wires  52 . The heating elements have much lower electrical resistance than the steel typically used for forceps jaws.  
      The surgeon maneuvers the endoscope into the desired area, such as the gastrointestinal tract. Biopsies in this area may include polyps. The hot biopsy forceps may include one or more heating elements, such as one heating element in one jaw and an optional heating element in the other jaw. The current may be bipolar, as in alternating or direct current electricity, or monopolar current may be used. The surgeon maneuvers the jaws in place around the desired sample and closes the jaws. Current is applied for a period sufficiently long to free the sample from its environment and to retrieve the sample inside the jaws for subsequent analysis.  
       FIG. 6  depicts another embodiment of a back-loading instrument, a forceps with a sharp cutting tool and a spike. In this embodiment, the back loading forceps  60  constitutes the distal portion of a the instrument and includes an upper jaw  61 , a lower jaw  62 , a control linkage  63  for controlling upper jaw  61 , a control linkage  64  for controlling lower jaw  62 , a spike  65 , and a control portion  66  for connecting control linkages  63 ,  64  to control cable  68 . Control cable  68  leads back through sheath  67 . In this embodiment, sheath  67  may be a coiled wire spring with a smooth coating  69 , such as a Teflon® coating. The outer diameter of sheath  67  preferably is about 2.4 to 2.6 Fr or narrower, and the inner diameter is sufficient so that control cable  68  does not bind or chafe during operation of the forceps. In the embodiment depicted in  FIG. 6 , the surgeon may maneuver the forceps to impale the spike  65  on a tissue or sample of interest. The surgeon then operates the forceps to sever the sample and remove it from the patient for later pathological examination.  
      Other embodiments with less complicated mechanical linkages may also be used.  FIG. 7  depicts a flexible forceps  70 , in which a sleeve  71  controls the opening and closing of forceps jaws  72 . In this embodiment, jaws  72  may be stamped from a single piece of metal and formed into the desired shape. The jaws are secured to a short cannula  73  and to control rod  75  with a joint  74 , which may be formed from a solder joint, a braze joint, a small rivet, or other desired form to secure the jaws to the cannula. Joint  74  could also take the form of a fastener threaded into the cannula to secure the jaws to the cannula. Cannula  73  is secured to control rod or cable  75  by swaging, soldering, brazing or other desired method, including a threaded joint.  
      Control rod  75  and sleeve  71  are back-loaded into a medical instrument, such as an endoscope or ureteroscope. In this embodiment, jaws  72  when closed are about 4 Fr in diameter, while sleeve  71  containing control rod  75  is about 2.6 Fr in diameter. The larger jaws enable the surgeon to take a larger biopsy sample from a patient in a single sampling procedure, thus taking less time and causing less trauma to the patient. There is a tapered or camming surface  76  to control the opening and closing of the jaws as sleeve  71  is retracted or control rod  75  is advanced.  
      Another embodiment uses a control rod that separates into two control wires to actuate the grasper or forceps at the distal end.  FIG. 8  depicts back-loading grasper having a hollow coil  81 , a control rod  83  and an end-effector  82  with a grasper  84 . The end-effector is firmly affixed to coil  81  by any suitable method, such as by soldering or brazing. Other methods of attachment may also be used. Grasper  84  at the distal end includes jaws  85  and control links  86  that are connected to wires  83   a  connected to the control rod. The jaws, even when closed, are too large to be drawn into coil  81 , and have a larger diameter or periphery than coil  81 . The coil may also have a smooth coating  88 , such as a PTFE coating. The grasper is preferably actuated by means of an endoscope or other therapeutic or diagnostic device. The device extends or retracts control rod  83 , causing the links  86  to pivot about pivot pin  87 , and causing jaws  85  to open or close. The sample or object is thus grasped and removed from the person.  
      Other embodiments may use a cylinder at the distal end to aid in a sampling procedure using a back-loading instrument.  FIGS. 9 and 10  depict such embodiments in a closed position.  FIG. 9  depicts a back loading extractor  90  that includes a spring-coil  91 . Coil  91  is reinforced on a portion of its distal end with a thin cylinder  92 . The cylinder is preferably metal, such as stainless steel, that does not interfere with patient care or with extraction of a sample or of an object from the body. The cylinder may be soldered or brazed to the coil, or otherwise attached firmly so that it will not come off the coil.  
      The extractor is controlled by a control rod  93  inside the coil, the control rod firmly attached to extractor  94  with jaws  95 . The attachment  98  may be made by a braze joint, solder joint, a fastener such as a rivet, or any other suitable joint. Extractor  94  may be made from stainless steel and is preferably made from Nitinol® or other shape memory metal so that the jaws automatically open when control rod  93  urges jaws  95  forward. The extractor has a tapered or camming surface  96 , allowing the jaws to spring open as control rod  93  urges jaws  95  forward. Coil  99  and proximal ends (not shown) of the outer coil spring and the control rod may be additionally coated with plastic or other atraumatic coating so that they do not damage an endoscope or other instrument into which the back loading instruments are placed.  
       FIG. 10  depicts another embodiment of a back-loading endoscopic instrument  100  in the closed position. Instrument  100  includes a coil  101  firmly attached to a grasper  105  with connection  107 . Connection  107  may be a braze joint, a solder joint, a fastener, or other convenient joint, so that grasper  105  does not detach from coil  101 . Because grasper  105  is brazed or otherwise joined to coil  101 , jaws  108  can only open or close, and cannot translate relative to coil  101 . Control rod  103  passes through joint  107  and through a slot (not shown) in the proximal portion of grasper  105 , allowing the control rod and cylinder to translate relative to coil  101  and grasper  105 .  
      Control rod  103  controls the opening and closing of jaws  108  via a tapered or camming surface  106  of the grasper, using a cylinder  104  attached to control rod  103 . The attachment  103   a  may be any suitable attachment, such as a braze joint, a solder joint, a fastener, or a weld, so that the cylinder does not detach from the control rod. When control rod  103  retracts cylinder  104 , jaws  108  open as the camming surfaces  106  allow. When control rod  103  advances, jaws  108  close, following the same camming surfaces.  
      The outer diameter of cylinder  104  is preferably no more than 2.8 Fr, more preferably about 2.6 Fr, and that of coil spring  101  about 2.4 Fr or less. Grasper  105 , camming surfaces  106 , and jaws  108  are preferably made from spring steel, stainless steel or a shape memory alloy, such as Nitinol®. The grasper may be stamped from a single continuum of metal and formed into the desired shape. Alternatively, the grasper may be made from several smaller pieces and joined together, by brazing or soldering or by any other suitable method. In this embodiment, the outer diameter of jaws  108  in the closed position is greater than the outer diameter of cylinder  104  and of coil  101 . In one embodiment, the outer diameter of the jaws is about 4 Fr. Other embodiments may be smaller or larger, but in any case the outer periphery or circumference of the jaws is greater than the inner diameter of cylinder  104 , and the jaws are not able to be retracted into the cylinder.  
      A variety of handles or control devices may be used with embodiments of the endoscopic instruments of the present invention. Handles that may be suitable include those depicted in  FIGS. 11-14 .  FIG. 11  depicts one suitable handle or control device  110 . A sheath  112  and control rod  114  from a back-loading endoscopic instrument are attached to the control device  110 . In this instance, sheath  112  is fixed to an attachment  113  at a distal end of the control device, while control rod  114  is attached to a movable button  111  for movement by a user. The control rod may be tightened or loosened by knob  115  controlling an internal collet (not shown) or other attachment device. The user controls the device by gripping the handle with the body  117  and fixed finger handles  116  and manipulating control button  111 . In other embodiments, the control rod may be fixed and the sheath attached to the collet and movable button.  
       FIG. 12  depicts a pin vise  120 , typically used to control only one of a control rod and sheath. Pin vise  120  may comprise only a handle  121  at its proximal end and a collet  124  at its distal end, used to attach a control element  125  from a back-loading endoscopic instrument. The control element may be a fixed or a movable control rod, or may be a fixed or a movable sheath. Two pin vises may be used, one for a control rod and one for a sheath, the control rod at least partially contained within the sheath.  
       FIG. 13  depicts another handle or control device  130  for controlling both a fixed and a movable control element. Handle  130  includes a body  131  at a proximal end, a movable control button  133  and a distal end  135 . In this embodiment, a sheath  134  from a back-loading endoscopic instrument is fixedly attached to the distal end  135 , and a control rod  132  is attached to the movable control button  133 . A user controls the endoscopic instrument by manipulating control button  133  back and forth to extend or retract control rod  132 . In other embodiments, the sheath may be attached to the movable button and the control rod fixed to the distal end of the handle.  
      A thumb-ring type handle  140  is depicted in  FIG. 14 . The handle attached a sheath  141  fixedly and a control rod  142  movably. Control rod  142  is attached to a cross piece  144  by means of a set screw  145 . The cross-piece is attached to a movable finger-spool  146 . A user holds the handle securely with thumb-ring  147  and controls the device by manipulating movable finger-spool  146  back and forth, extending or retracting control rod  142  and thus operating the back-loading endoscope instrument. In grasper and forceps types of instruments, the control rod may comprise more than a single control rod, e.g., two rods operating two jaws. In other embodiments, the sheath may be movable and the control rod fixed to the distal end of the handle.  
      It should be understood that the use of larger instruments for back loading is not limited to endoscopes or ureteroscopes. Thus, back-loading instruments may be used on a variety of medical instruments, including hysteroscopes, colonoscopes, gastroscopes, laparoscopes, and so forth. The back-loading instruments may be used in these and in many other applications in which the surgeon wishes to keep trauma and invasiveness to a minimum. Of course, these instruments may also be used in other applications, such as a bronchoscope, in which their small size is still an advantage.  
      The details of the construction or composition of the various elements of the back loading medical instruments not otherwise disclosed are not believed to be critical to the achievement of the advantages of the present invention, so long as the elements possess the strength, sharpness, and flexibility needed for them to perform as disclosed. The selection of such details of construction is believed to be well within the ability of one of even rudimentary skills in this area, in view of the present disclosure, and are within the spirit of the invention and the scope of the claims. It will be understood that no limitation of the scope of the invention is intended by the above description and drawings, which is defined by the claims below. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.