Patent Publication Number: US-2006009680-A1

Title: Endoscope valve assembly and method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of co-pending U.S. patent application Ser. No.10/271,485, filed Oct. 16, 2002, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/022,134, filed Dec. 12, 2001, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 09/761,784, filed Jan. 17, 2001. Each of these applications is hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND  
      The present invention relates to endoscopic surgical devices, and in particular to valve assemblies used to control the flow of irrigation fluid in such devices.  
      Endoscopic devices are customarily provided with an irrigation port that conducts an irrigation liquid to the viewing area at the end of the endoscopic device. One prior-art approach is to pressurize irrigation fluid in an IV fluid bag, and then to supply the pressurized irrigation fluid directly into an endoscope such as a ureteroscope. The endoscope includes integral valves that are generally operated with one hand while the other hand holds the handpiece of the endoscope. The advantage of this system is that the irrigation fluid is pressurized, thereby providing dilation of a ureter and good visibility. One potential disadvantage with this type of irrigating system is that it may be difficult to control fluid flow since two hands are required. If the fluid flow is not controlled properly, a stone can be dislodged back into the middle or upper ureter by an excessively high rate of flow. Also, in the event of extravasation, uncontrolled amounts of fluid can flow into the retroperitoneum.  
      Another type of irrigation system is a hand-operated, pressurized irrigating system commercially manufactured by Bard, Boston Scientific, and ACMI. This approach allows the amount of fluid being injected to be controlled, but the apparatus is relatively bulky. This system is mounted separately from the ureteroscope, and separate hands are used to hold the handpiece of the ureteroscope and to control the flow of irrigation fluid. On occasion, an assistant controls fluid flow while the physician holds the endoscope in the left hand and performs an endoscopic procedure with the right hand. In this case, precise control of the rate of fluid flow is difficult, because oral instructions are slower and less precise than direct manual control by the physician.  
      A third type of irrigation system includes two or more syringes that are operated by an assistant one at a time to supply pressurized irrigation fluid to the endoscopic device. Generally a valve is provided that allows the assistant to fill one of the syringes while the other is in use.  
      A fourth type of irrigation system includes a roller pump mechanism that delivers irrigation fluid at a constant set pressure. This system may incorporate a blow-off valve to prevent excessive pressure, and it is generally used in endoscopic specialties such as orthopedics in performing arthroscopies. This system requires the use of an electric motor and controller, and it is therefore costly and bulky.  
      Goodman U.S. Pat. No. 4,567,880 discloses an endoscopic device having a three-way valve forming a permanent portion of the handpiece of the endoscope. This system allows a physician to control the flow of irrigation fluid with the same hand as that used to hold the handpiece. However, the Goodman system requires a specially constructed endoscope, and the irrigation system is an integral part of the endoscope. This limits the irrigation system to use with one particular endoscope.  
      The present invention is directed to an improved system and method for controlling the flow of irrigation fluid in an endoscopic device.  
     SUMMARY  
      The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims.  
      By way of introduction, the preferred embodiments described below relate to an endoscope valve assembly comprising a housing comprising an inlet port and an outlet port, and a valve carried by the housing. The valve comprises a manually-controlled actuator movable between a first position, in which the valve blocks flow between the inlet port and the outlet port, and a second position, in which the valve allows flow between the inlet port and the outlet port. In one embodiment, a mounting pad is coupled to the housing and comprises a resilient material. The surface of the mounting pad opposite the housing comprises a non-linear shape. In another embodiment, a mounting pad is coupled to the housing, and the valve assembly further comprises a strap secured to the housing and a mounting buckle movable along the strap. Other embodiments are described, and each of the embodiments can be used alone or in combination with each other.  
      The embodiments will now be described with reference to the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a ureteroscope on which is mounted a modular valve assembly.  
       FIG. 2  is a top perspective view of the valve assembly of  FIG. 1 , prior to mounting on the ureteroscope.  
       FIG. 3  is a bottom perspective view of the valve assembly of  FIG. 2 .  
       FIG. 4  is a perspective view of the valve assembly of  FIGS. 2 and 3  connected to a source of pressurized irrigation fluid.  
       FIGS. 5 and 6  are schematic views showing the valve of the valve assembly of  FIGS. 1-3  in the opened and closed positions, respectively.  
       FIGS. 7 and 8  are schematic views of an alternative, rotary-motion valve in the opened and closed positions, respectively.  
       FIG. 9  is a fragmentary sectional view of another modular valve assembly of this invention mounted on a ureteroscope.  
       FIG. 10  is a fragmentary sectional view of yet another modular valve assembly of this invention.  
       FIG. 11  is a fragmentary sectional view of the ureteroscope of  FIG. 10  and a cover plate.  
       FIG. 12  is a fragmentary sectional view of another modular valve assembly of this invention mounted on a ureteroscope.  
       FIG. 13  is a cross-sectional view of another modular valve assembly of this invention including a mechanical latch to hold the valve in a selected position.  
       FIGS. 14, 15  and  16  are three sectional views of another modular valve assembly of this invention in three different positions.  
       FIG. 17  is a sectional view of another modular valve assembly of this invention.  
       FIGS. 18, 19  and  20  are side views of three additional modular valve assemblies of this invention.  
       FIG. 21  is a perspective view showing an endoscope valve assembly releasably secured to an index finger of a hand holding an endoscope.  
       FIG. 22  is a perspective view showing an endoscope valve assembly releasably secured to a thumb of a hand holding an endoscope.  
       FIG. 23  is a perspective view showing an endoscope valve assembly releasably secured to a palm of a hand holding an endoscope.  
       FIG. 24  is a perspective view of an endoscope valve assembly of one embodiment.  
       FIG. 25  is an exploded view of the endoscope valve assembly of  FIG. 24 .  
       FIG. 26  is a sectional view taken along line  26 - 26  of  FIG. 25 .  
       FIG. 27  is an illustration of an endoscope valve assembly of another preferred embodiment.  
       FIG. 28  is an illustration of a valve of the endoscope valve assembly of  FIG. 27 .  
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS  
      Turning now to the drawings,  FIG. 1  is a perspective view of an endoscopic device  10  that in this embodiment is a ureteroscope. The ureteroscope  10  includes a handpiece  12  that carries an eyepiece  14  at one end and a shaft  16  at the other end. An irrigation port  18  is carried by the handpiece  12 , and irrigation fluid introduced via the irrigation port  18  is conducted to the viewing area at the end of the shaft  16  that is inserted into the patient. The handpiece  12  also defines an exterior surface  20 .  
      The endoscopic device  10  can take any suitable form, and the present invention is not limited to any particular embodiment. For example, the endoscopes of any of the following U.S. Patents can be adapted for use with this invention: Wallace U.S. Pat. No. 2,691,370, Ibe U.S. Pat. No. 4,132,227, Goodman U.S. Pat. No. 4,567,880, Cho U.S. Pat. No. 5,083,549, Muller U.S. Pat. No. 5,199,417, Bonati U.S. Pat. No. 5,290,279, and Odanacka U.S. Pat. No. 5,830,126. Conventional endoscopes such as the ureteroscopes manufactured by ACMI, Wolf, Olympus and Storz are also well-adapted for use with this invention. This list is intended only by way of illustration, in the widest variety of ureteroscopes, arthroscopes, laparoscopes, hysteroscopes, sinuscopes, and endoscopes adapted for other specialties can be used with this invention, including flexible, semi-rigid, and rigid endoscopes.  
      In use, the physician holds the handpiece with one hand, thereby presenting the eyepiece for viewing and positioning the shaft as desired. The other hand is typically used to manipulate surgical tools introduced into the patient via the working port on the shaft. As shown in  FIG. 1 , a modular endoscope valve assembly  30  is releasably secured to the handpiece  12 . This valve assembly  30  is shown in greater detail in  FIGS. 2 and 3 , and it includes an inlet port  32  and an outlet port  34 . In use the inlet port  32  is releasably connected to a source of pressurized irrigation fluid, and the outlet port  34  is releasably connected to the irrigation port  18  of the handpiece.  
      The valve assembly  30  includes a valve that is interposed between the inlet port  32  and the outlet port  34  and is controlled by a valve actuator  38 . The valve assembly  30  also includes a housing  50  that includes a mounting surface  52 . The mounting surface  52  carries a pressure-sensitive adhesive  40  initially covered by a release paper  46 . The housing  50  also supports a pair of straps  42  that include respective hook-and-loop fasteners  44 . A contrast-introduction port  48  is provided in fluid communication with the outlet port  34 . Check valves, not shown, can be provided to prevent flow from the outlet port  34  to the contrast-introduction port  48  and vice-versa.  
       FIG. 4  shows the manner in which the inlet port  32  of the valve assembly  30  can be releasably connected to a source of pressurized irrigation fluid, in this case contained within an IV bag  60 . The IV bag  60  is disposed within a pressure cuff  62  that can be inflated with an inflator  64  to a pressure indicated by a pressure gauge  66 . Standard Luer-lock fittings can be used to connect the inlet port  32  to a tube  68  that is in turn connected to the IV bag  60 . The IV bag contains a conventional irrigation fluid, which is pressurized by inflating the pressure cuff  62  to a desired pressure with the inflator  64 .  
       FIGS. 5 and 6  show two schematic views of the valve  36  of the valve assembly  30 . In  FIG. 5  the valve actuator  38  is depressed and the valve  36  allows fluid flow from the inlet port  32  to the outlet port  34 . When manual pressure is removed from the valve actuator  38 , the valve  36  returns to the position of  FIG. 6 , in which the valve  36  blocks the flow of fluid between the inlet and the outlet ports  32 ,  34 . Alternatively, the valve  38  may be arranged such that fluid flow is blocked when the actuator  38  is depressed and unblocked when the actuator  38  is released.  
      The valve  36  of  FIGS. 5 and 6  is a linear valve that slides along a linear axis between the opened position of  FIG. 5  and the closed position of  FIG. 6 . Other types of valves are suitable, including the linear valve of U.S. Pat. No. 4,238,108 and the rotary valve  80  of  FIGS. 7 and 8 . A rotary valve  80  rotates about an axis between the opened position of  FIG. 7  and the closed position of  FIG. 8 , and the associated valve actuator (not shown in  FIGS. 7 and 8 ) moves in a rotary motion as well.  
      In use, the valve assembly  30  is distributed separately from the endoscope  10 . In this embodiment, the valve assembly  30  is shaped to fit on a wide variety of endscopes  10  such that the endoscope  10  does not have to be specially shaped or configured for the valve assembly  30 . Prior to an endoscopic procedure, the release paper  46  is removed, thereby exposing the pressure-sensitive adhesive  40  on the mounting surface  52 . Then the valve assembly  30  is placed on the exterior surface  20  of the endoscope  10 , and the pressure-sensitive adhesive  40  releasably holds the valve assembly  30  in place. The straps  42  are positioned around the handpiece  12 , and the hook-and-loop fasteners  44  are secured together to hold the valve assembly  30  in place.  
      Either before or after the valve assembly  30  is secured to the handpiece  12 , the inlet port  32  is releasably secured to the tube  68  ( FIG. 4 ) and the outlet port  34  is releasably secured to the irrigation port  18  of the handpiece  12  ( FIG. 1 ). Preferably, the valve assembly  30  is flushed after it is connected to the tube  68  and before it is connected to the irrigation port  18 .  
      The physician then performs the desired endoscopic procedure, using a single hand both to hold the handpiece  12  and to control the flow of pressurized irrigation fluid with the valve assembly  30 . A part of the hand that holds the handpiece (e.g. the fingers or the heel) is used to move the valve actuator.  
      Once the endoscopic procedure has been completed, the valve assembly  30  can simply be removed from the endoscope  10  by releasing the hook-and-loop fasteners  44  and lifting or twisting the valve assembly  10  away from the handpiece  12  until the pressure-sensitive adhesive  40  releases.  
      The valve assembly  30  described above uses both a pressure-sensitive adhesive and a set of straps to releasably secure the valve assembly  30  in place on the handpiece  12 . In alternative embodiments the adhesive may be used without the reinforcing straps, or the reinforcing straps can be used without the adhesive. The strap may be varied widely. For example, the strap may pass over the top of the valve assembly, and the actuator may pass through an opening in the strap. The strap may be fixed to the valve assembly or not. Also, other types of fasteners can be used to releasably hold the valve assembly in place on the endoscope.  
       FIG. 9  shows a second preferred embodiment  90  of the modular valve assembly of this invention. The valve assembly  90  is identical to the valve assembly  30  described above except for the manner of releasably attaching the valve assembly  90  to the handpiece  12 ′. In this case the valve assembly  90  is provided with mechanical fasteners  92  and the handpiece  12 ′ is provided with mating mechanical fasteners  94  such that the valve assembly  90  can be snapped in place on the handpiece  12 ′ and removed from the handpiece  12 ′ as desired. In this example, the fasteners  92  take the form of protruding studs and the mating fasteners  94  take the form of recesses shaped to receive the fasteners  92  in a snap-lock action.  
       FIG. 10  shows portions of a third valve assembly  100  which is similar to that of  FIG. 9  except that the fasteners  102  are shaped as recesses and the mating fasteners  104  are shaped as protruding studs that fit into the fasteners  102  in a snap-lock manner.  
       FIG. 11  shows the handpiece  12 ″ of  FIG. 10  with a cover  110  snapped in place on the mating fasteners  104 . The cover  110  covers the mating fasteners  104  when a valve assembly is not in place on the handpiece  12 ″.  
       FIG. 12  shows another modular valve assembly  120  mounted in place on the handpiece  12  of an endoscopic device. The valve assembly  120  includes an actuator  122 , an inlet port  124 , and an outlet port  126 . The valve assembly  120  is mounted on a base  130 , and the base  130  supports a spring clip  128  that is designed to fit at least partially around the handpiece  12  and to releasably hold the base  130  and therefore the valve assembly  120  in position on the hand-piece  12 . The spring clip  128  is another example of a mechanical fastener that is suitable for releasably securing a modular valve assembly to an endoscopic device. In this example, the outer surface of the handpiece  12  can be considered a mating fastener that cooperates with the spring clip  128  to releasably hold the valve assembly  120  in place on the endoscopic device. The details of construction of the modular valve assembly  120  can be varied widely, in accordance with any of the other valve assemblies described in this specification.  
       FIG. 13  provides a sectional view of another modular valve assembly  140 . The modular valve assembly  140  includes a housing  142  that supports an inlet port  144  and an outlet port  146 . A valve element  148  is slidably received in a cylinder defined by the housing  142 , and the valve element  148  defines an annular recess  150 . The annular recess  150  completely encircles the valve element  148 , and thereby provides an interconnecting flow path between the inlet port  144  and the outlet port  146  when the recess  150  is aligned with the ports  144 ,  146 . The valve element  148  is biased to the upper position shown in  FIG. 13  by a spring  152 . The valve assembly  140  includes an actuator  156  that can be pressed downwardly by a finger of the user. A latch  154  is interposed between the actuator  156  and the valve element  148 , and the latch  154  operates to hold the valve element  148  in a selected position.  
      In use, the inlet port  144  is coupled to a source of irrigation fluid and the outlet port  146  is coupled to the irrigation port of an endoscopic device. In the position shown in  FIG. 13 , the recess  150  is out of alignment with the inlet and outlet ports  144 ,  146 , and no irrigation fluid is passed to the outlet port  146 . When the user presses the actuator  156  downwardly in the view of  FIG. 13 , the recess  150  comes into alignment with the inlet and outlet ports  144 ,  146 , thereby permitting irrigation liquid to flow to the endoscopic device. Further downward movement of the actuator  156  causes the latch  154  to hold the valve element  148  in a position in which the recess  150  is aligned with the inlet and outlet ports  144 ,  146 . Once the latch  154  is engaged, the user can take his or her hand off of the actuator  156 , and high volume flow of irrigation fluid is maintained from the inlet port  144  to the outlet port  146 .  
      In order to stop the flow of irrigation fluid, the user again depresses the actuator  156 , thereby causing the latch  154  to release the valve element  148  to move upwardly, back to the position of  FIG. 13 .  
      The valve assembly  140  allows the user to modulate the flow of irrigation fluid as described above as he or she gradually depresses the actuator  156 . The latch  154  also allows the user to latch the valve in the open position, until it is released by the user.  
      Many alternative structures can be used for the latch  154 . For example, the latch  154  can be constructed like the latch mechanism conventionally used with retractable ballpoint pens. Such latch mechanisms respond to first depression of the actuator by latching the latched element down, and they respond to a next depression of the actuator by allowing the latched element to move upwardly. This is only one example, and many alternatives are possible.  
       FIGS. 14, 15  and  16  provide three views of another modular valve assembly  160  that can be used as described above. As best shown in  FIG. 14 , the modular valve assembly  160  includes a housing  162  that supports a valve element  164  for sliding movement. The valve element  164  defines two spaced, annular recesses  166 ,  168 , and the upper end of the valve element  164  forms an actuator  170 . The valve element  164  is biased to the upper position shown in  FIG. 14  by a spring  178 .  
      The housing  162  supports first and second inlet ports  172 ,  174  and aligned tubes  173 ,  175  that are connected to an outlet port  176 . The first inlet port  172  in use is connected to a liquid source, such as a source of irrigation fluid. The second inlet port  174  in use is connected to a suction source, such as a partial vacuum. The outlet port  176  in use is connected to an irrigation port of an endoscopic device. Check valves, not shown, may be used to prevent flow from the tube  173  to the tube  175  and vice-versa.  
      In the rest position of  FIG. 14 , the valve element  164  isolates both the first and second inlet ports  172 ,  174  from the outlet port  176 . This is because the first inlet port  172  is out of alignment with the first recess  166 , and the second inlet port  174  is out of alignment with the second recess  168 .  
       FIG. 15  shows the valve assembly  160  in a second position, in which the user has depressed the actuator  170 , thereby compressing the spring  178  and bringing the first recess  166  into alignment with the first inlet port  172  and the tube  173 . In this position, irrigation fluid from the liquid source is passed by the assembly  160  to the outlet port  176 .  
      As shown in  FIG. 16 , when the actuator  170  is further depressed, the first recess  166  is moved out of alignment with the first inlet port  172 , and the second recess  168  is moved into alignment with the second inlet port  174 . In this position, the valve assembly  160  allows suction from the suction source to pass via the second inlet port  174  and the second tube  175  to the outlet port  176 .  
      The modular valve assembly  160  of  FIGS. 14 through 16  is intended to be removably attached to the handpiece of an endoscopic device, all as described above. Any of the mechanisms described above for releasably securing the valve assembly to the handpiece can be used. The valve assembly  160  provides all of the functions described above regarding the valving of irrigation fluid from the liquid source to the outlet port  176 . In addition, the valve assembly  160  allows the physician efficiently and easily to introduce suction to the endoscopic device by moving the actuator  170  to the fully depressed position of  FIG. 16 . Thus, a single valve assembly controls both the introduction of irrigation fluid and the application of suction to the irrigation port of the endoscopic device.  
      The valve assembly  160  utilizes a linear slide valve to implement the valving functions described above. It should of course be understood that this invention is not limited to such linear slide valves, and that the widest variety of valve mechanisms can be used to perform these valving functions.  
       FIG. 17  shows a sectional view of another modular valve assembly  180  also intended to be releasably secured to the handpiece of an endoscopic device as described above. The modular valve assembly  180  includes a housing  182  that supports first and second valve elements  184 ,  185 . The first valve element  184  includes a first recess  186  and a first actuator  190 . The first valve element  184  is biased to the upper position shown in  FIG. 17  by a spring  198 . In this upper position the valve element  184  blocks the flow of liquid between a first inlet port  192  and a tube  193 . As shown in  FIG. 17 , the tube  193  is coupled to an outlet port  196 , which may in turn be coupled to an irrigation port of an endoscopic device as described above (not shown). When the first actuator  190  is depressed to bring the first recess  186  into alignment with the first inlet port  192  and the first tube  193 , irrigation fluid from a liquid source (not shown) passes from the first inlet port  192  to the outlet port  196 .  
      The second valve element  185  defines a second recess  188  and is biased to an upper position as shown in  FIG. 17  by a second spring  199 . The upper portion of the second valve element  185  is coupled to a second actuator  191 . In this non-limiting example, the second actuator  191  is arranged so that the physician can reach it from any side of the valve assembly  180 . This can be accomplished by forming the upper portion of the actuator  191  as a ring that encircles the housing  182 . Alternatively, the actuator  191  may include a swivel, not shown, that allows the physician to rotate the upper portion of the actuator  191  to a desired angular position relative to the lower portion of the actuator  191  about an axis parallel to the sliding motion of the second valve element  185 . In the rest position shown in  FIG. 17 , the second valve element  185  blocks the flow of suction from a second inlet port  194  to the tube  195  (which is in turn coupled to the outlet port  196 ). When the user depresses the second actuator  191  to bring the second recess  188  into alignment with the second inlet port  194  and the second tube  195 , suction is applied to the outlet port  196 .  
      The modular valve assembly  180  is provided with adhesive straps, mechanical fasteners, spring clips or the like for releasably securing it to the handpiece of an endoscopic device (not shown). The modular valve assembly  180  allows the user to control the flow of irrigation fluid and the application of suction to the outlet port  196 . In this case, the user moves his or her finger between the first and second actuators  190 ,  191  to provide irrigation fluid or suction to the outlet port  196 , respectively.  
       FIG. 18  shows another modular valve assembly  210  that performs all of the functions described above in conjunction with  FIGS. 16 and 17 . The modular valve assembly  210  includes a housing  212 ,  220  that supports two separate valves, each controlled by a respective actuator  214 ,  222 . The actuator  214  controls the flow of irrigation fluid between a first inlet port  216  and an outlet port  218 , and the second actuator  222  controls the introduction of suction from the second inlet port  224  to the outlet port  218 . In this case the actuators  214 ,  222  and the associated valves are positioned in side-by-side relationship, but at differing elevations to assist the user in discriminating between the two actuators  214 ,  222 .  
      The modular valve assembly  230  of  FIG. 19  is similar to the valve assembly  210 , except that in this case the two actuators are positioned at the same elevation.  
      The modular valve assembly  240  of  FIG. 20  is similar to the modular valve assembly  230 , but in this case the two valves are mounted some distance from one another on the handpiece  12 .  FIG. 20  shows the manner in which a housing may include two or more spatially separated parts.  
      The modular valve assemblies of  FIGS. 12 through 20  are all intended to be releasably mounted to an endoscopic device and to allow the user to control the flow of at least irrigation fluid to the irrigation port of the endoscopic device. The modular valve assemblies of  FIGS. 14 through 20  additionally allow the user to control the application of suction to the irrigation port. The valve assemblies of  FIGS. 14 through 20  are used in the same manner as the valves described above, except that the first inlet port  172 ,  192 ,  212  is connected to a source of irrigation fluid and the second inlet port  174 ,  194 ,  224  is connected to a source of suction prior to the surgical procedure. This can be done either before or after the modular valve assembly  160 ,  180 ,  210 ,  230 ,  240  is releasably mounted to the handpiece of the endoscopic device.  
      It should be apparent from the foregoing description that the improved modular valve assembly of this invention provides the important advantage that little or no modification is required to a conventional endoscope, yet the physician using the endoscope is provided with improved control over the flow of irrigation fluid. In particular, the physician can use direct finger pressure to modulate the flow of irrigation fluid as desired, while still leaving one hand free for surgical procedures. In this way, the need for a trained surgical nurse is reduced, and the physician&#39;s control over irrigation fluid flow is improved. The valve assembly described above is well suited for use with a wide variety of endoscopes including modern, small endoscopes that are too small for built-in valves.  
      Of course, it should be understood that a wide range of changes and modifications can be made to the preferred embodiments described above. For example, the valve of the valve assembly can take any suitable form, and it is not limited to the specific examples described above. The motion used to open or close the valve  36  can be varied as appropriate for the application, and it can include a lifting motion, a depressing motion, a sliding motion parallel to the length of the handpiece, or a rotating motion as desired. As a further alternative, the valve may be implemented as an element that pinches a resilient tube to slow or block flow through the tube. Thus, the valve can be implemented as a one-piece or a multiple-piece system having sliding, hinged, rotating or other motions.  
      Similarly, the mechanical fasteners that releasably hold the valve assembly in place on the handpiece of the endoscope can take any suitable form, and such fasteners are not limited to the adhesives, straps, snap-lock studs, and recesses described above. Many other mechanical fasteners can be adapted for use with this invention, as for example linear or rotary guides (including, e.g., dovetail guides or bayonet sockets) and various types of resilient or bendable elements that releasably hold the valve assembly in place.  
      In the embodiments described above, the valve assembly was releasably secured to the endoscope. In another embodiment, the valve assembly is releasably secured to a hand of a user using the endoscope instead of to the endoscope itself.  FIGS. 21-23  show several illustrations of this embodiment. Like the valve assembly described previously, the valve assembly  330  of this embodiment comprises a housing  350 , an inlet port  332 , an outlet port  334 , and a valve comprising a manually-controlled actuator  338 . The inlet port  332  is connected with a source of pressurized or non-pressurized irrigation fluid, and the outlet port  334  of the valve assembly  330  is connected with the irrigation port  318  of the endoscope  310 . In the illustrations shown in  FIGS. 21-23 , a coiled tubing  395  is used to connect the outlet port  334  of the valve assembly  330  with the irrigation port  318  of the endoscope  310 . Because the tubing  395  is coiled, the valve assembly  330  can be located relatively close to the irrigation port  318  without excess tubing getting in the way of the user. Additionally, the coiled tubing  395  is expandable (like a telephone cord) to allow the valve assembly  330  to be located relatively far away from the irrigation port  318 . Further, by being coiled, the tubing  395  is more kink resistant than non-coiled tubing.  
      The valve assembly  330  comprises a securing element  400  coupled with the housing  350  and operative to releasably secure the housing  350  to a hand of a user using the endoscope  310 . In one implementation (shown in  FIG. 24 ), the securing element  400  takes the form of a strap with hook-and-loop fasteners (e.g., a Velcro™ strap) that is secured to one side of the housing  350  in any suitable manner (e.g., glued, stitched, or riveted). The other side of the housing  350  contains a “D-loop”  410  through which the loose end of the strap  400  can be wrapped. One side of the strap  400  contains hooks, and the other side contains loops such that when the loose end of the strap  400  is wrapped around the D-loop  410 , the strap  400  can secure to itself. In one implementation, the width of the strap  400  is about 1.5 cm wide.  
      In  FIG. 21 , the valve assembly  330  is releasably secured to the index finger of the user&#39;s hand  300 , and the user moves the actuator  338  with his thumb. The design of the securing element  400  allows the valve assembly  330  to be releasably secured to other parts of the user&#39;s hand  300 . For example, in  FIG. 22 , the valve assembly  330  is releasably secured to the user&#39;s thumb, and the actuator  338  is moved with the user&#39;s index finger. It should be noted that while  FIGS. 21 and 22  show the valve assembly  330  being secured to a single digit, the valve assembly  330  can be secured to two or more digits. In  FIG. 23 , instead of being secured to a digit, the valve assembly  330  is releasably secured to the user&#39;s palm, and the actuator  338  is moved using one of the user&#39;s digits (here, a finger).  FIGS. 21-23  show only some of the many possible positions of the valve assembly  330 , and other positions are possible. For example, the valve assembly  330  can be secured to the user&#39;s finger, and the actuator can be moved by pressing the valve assembly  330  against the user&#39;s palm.  
      There are several advantages associated with securing the valve assembly to the user&#39;s hand instead of to the endoscope. Although the valve assembly of these embodiments can be releasably secured to a wide variety of endoscopes, it is contemplated that some endoscopes may not have the space or a convenient location for the valve assembly to secure to. By securing the valve assembly to the user&#39;s hand, the user can ensure that the valve assembly can be used with any type of endoscope and can be positioned in a location the user&#39;s finds convenient. Additionally, a user may not wish to use some types of securing elements with an endoscope. For example, a pressure-sensitive adhesive may leave an undesirable residue on an endoscope. Securing the valve assembly to the user&#39;s hand avoids this possible disadvantage.  
      In the illustrations shown in  FIGS. 21-23 , the valve assembly was secured to the same hand as that holding the endoscope. This allows the user to use a single hand to both hold the endoscope and to control the flow of irrigation fluid. In an alternate embodiment, the user holds the endoscope in one hand and releasably secures the valve assembly to his other hand. This allows the user to hold the endoscope in one hand and manually control the fluid flow with the other hand, which is typically used to manipulate surgical tools introduced into the patient via a working port in the endoscope. One such surgical tool is an endoscopic stone-destruction device (e.g., a destructive laser fiber), and another such tool is an endoscopic stone-extraction device. U.S. Pat. No. 6,419,679, which is by the same inventor as the present application and is hereby incorporated by reference, describes such devices. In another alternate embodiment, the valve assembly for the endoscope is releasably secured to the second medical instrument (such as the handle of an endoscopic stone-destruction or stone-extraction device) instead of to the hand of the user.  
      It should be noted that, although a strap with hook-and-loop fasteners was used in the illustrations in  FIGS. 21-24 , any other type of suitable securing element can be used such as the securing elements previously discussed (e.g., a pressure-sensitive adhesive, straps without hook-and-loop fasteners, resilient or bendable elements, etc.). Some specific examples within these general categories include, but are not limited to, a ring that fits over the user&#39;s digit, a stretchable band, a mechanical fastener secured to the valve assembly that engages with a mating fastener secured to the user&#39;s hand, elements that can be tied around the user&#39;s hand, a deformable material through which a user slides part of his hand (e.g., a digit) into and out of, magnets, etc. The securing element can also take the form of a digit sheath or glove that the user wears on his hand. As illustrated by these examples, the securing element can be a single- or multiple-piece design, can be continuous or broken, and can be made from a rigid or resilient material. Further, the type of securing element can be chosen such that the valve assembly can be secured to both the user&#39;s hand and to the endoscope (or to another medical instrument), thereby giving the user maximum flexibility in choosing where to position the valve assembly. Additionally, two (or more) securing elements can be used. For example, one securing element can be used to secure the valve assembly to the endoscope, and another securing element can be used to secure the valve assembly to the user&#39;s hand. Preferably, the securing element that is not used (e.g., the “hand” securing element) does not interfere with the securing element that is being used (e.g., the “endoscope” securing element).  
      Turning again to the drawings,  FIGS. 25 and 26  are illustrations of one suitable valve design.  FIG. 25  is an exploded view showing the components of the valve. The housing  330  comprises two parts: a cap  500  and a base  510 . In this embodiment, the actuator  338  extends about 0.7 cm above the top of the housing  350  when assembled, the width of the actuator  338  is about 0.5 cm, and the housing  330  and the actuator  338  are made of plastic. Although not shown in  FIG. 25 , a rubber sponge can be placed on the bottom of the base  510  to (1) provide additional friction to help prevent the valve assembly  330  from slipping off the user&#39;s hand, (2) provide a comfortable surface for the user, and (3) prevent scratching of the endoscope  310  when the valve assembly  330  is secured to the endoscope  310  instead of to the user&#39;s hand.  
      The actuator  338  is part of a plunger-type component  520  comprising a spring  530 , a disk  540 , and a rubber gasket  550 . As shown in  FIG. 26 , the top surface of the cap  550  contains two holes  560 ,  570 . Hole  560  leads to the inlet port  332 , and hole  570  leads to the outlet port  334 . When assembled, the spring  530  biases the disk  540  and rubber gasket  550  against the top surface of the cap  500  and prevents flow between the inlet and outlet ports  332 ,  334 . In this configuration, the actuator  338  is in a first position. When the user presses on the actuator  338 , the actuator  338  moves to a second position, in which the disk  540  and rubber gasket  550  are spaced away from the holes  560 ,  570 . This allows fluid to flow between the inlet and outlet ports  332 ,  334 . When the user releases the actuator  338 , the spring  530  returns the actuator  338  to the first position, and the disk  540  and rubber gasket  550  once again block flow between the inlet and outlet ports  332 ,  334 .  
      It should be understood that other valve mechanisms can be used. Additionally, it is contemplated that other valve designs may provide advantages over the valve design shown in  FIGS. 25 and 26 . For example, it may be preferred to use a valve design that provides a graded flow (instead of a binary flow) so that the user can control the amount and rate at which the irrigant enters the endoscope (e.g., a few drops to full flow). To achieve this result, it may be preferred to use a valve design in which a blocking element moves past the inlet and/or outlet ports. Additionally, to provide a finer degree of control, it may be preferred to design the length of the actuator  338  to be more than 0.7 cm above the surface of the housing  350 . Additionally, to reduce stress on the user&#39;s hand, it may be preferred to design the width of the actuator  338  to be more than 0.5 cm and to provide the actuator  338  with a smooth, comfortable surface. Further, it may be preferred to use a relatively-low spring resistance to allow the user to easily press the actuator  338 .  
      It should also be understood that any of the embodiments previously described herein can be used in combination with the embodiments shown in  FIGS. 21-26 . For example, the valve assembly can be constructed with an additional inlet port for connection to a suction source. The same or second valve (with a second actuator) can be used to control suction flow. As another example, a latch mechanism, such as the ones conventionally used with retractable ballpoint pens, can be used to lock the actuator in a position at a full flow. Once the latch is engaged, the user can take his hand off the actuator, and high volume flow of irrigation fluid will be maintained from the inlet port to the outlet port. To stop the flow of irrigation fluid, the user again depresses the actuator, thereby causing the latch to release the actuator to move upwardly and stop the flow. This is only one example of a suitable latch, and many alternatives are possible.  
      Turning again to the drawings,  FIG. 27  shows an endoscope valve assembly  600  of another preferred embodiment. It is important to note that any and all of the features described above with respect to the other preferred embodiments can be used with the preferred embodiments shown in this figure. The valve assembly  600  comprises a housing  605 , an inlet port  610 , and an outlet port  615 . A valve is carried by the housing  605  and comprises a manually-controlled actuator  620 .  FIG. 28  shows the valve in more detail.  
      As shown in  FIG. 28 , the actuator  620  is coupled with a valve element  625 . The valve element  625  comprises a stem  630  and first and second O-rings  635 ,  640  at either end of the stem  630 . The valve element  625  is biased upwardly by a spring  645 . When the actuator  620  is not depressed, the spring  645  biases the valve element  625  upwardly, such that the second O-ring  640  presses against an internal tapered portion  650  of the housing  605 . In this position, the second O-ring  640  prevents flow between the inlet port  610  and the outlet port  615 . When the actuator  620  is depressed, the spring  645  is compressed, the valve element  625  moves downwardly, and the second O-ring  640  moves away from the tapered portion  650 . This allows flow between the inlet port  610  and the outlet port  615 . The amount of flow between the inlet port  610  and the outlet port  615  is determined by how completely depressed the actuator  620  is. If the actuator  620  is only slightly depressed, the flow between the inlet port  610  and the outlet port  615  will be “drop-by-drop.” If, however, the actuator  620  is completely depressed, the flow between the inlet port  610  and the outlet port  615  will be free flowing.  
      Returning to  FIG. 27 , first and second tubings  655 ,  660  are connected to the inlet port  610  and the outlet port  615 , respectively. A female luer  657  and female luer cap  659  are located at the end of the first tubing  655 . In operation, the female luer cap  659  is removed to connect the female luer  657  to an irrigation fluid source. The second tubing  660  is connected to an inline check valve  662 , which connects to a third tubing  664 . The third tubing  664  connects to a Y-site injection port  665 , which is connected to a fourth tubing  667 . At the end of the fourth tubing  667  are a male luer with a free-spinning hub  668  and a male leur cap  669 . In operation, the male cap  669  is removed to connect the male luer  668  to the endoscope. It is presently preferred that the tubings  655 ,  660 ,  664 ,  667  be made of PVC (Colorite 8511G-015, 85 Shore A).  
      In this embodiment, the valve assembly  620  also comprises a mounting pad  670  coupled to the housing  605 , a strap  675  secured to the housing  605 , and a mounting buckle  680  movable along the strap  675 . While the mounting pad  670  is preferably separately formed from the housing  605 , the mounting pad  670  can be integral with the housing  605 . To releasably secure the valve assembly  620  to an endoscope (as mentioned above, the valve assembly  620  can also be releasably secured to a second medical instrument or to a user&#39;s hand (e.g., digits or palm)), a user places the mounting pad  670  on a surface of the endoscope and moves the mounting buckle  680  along the strap  675  to a position opposite the mounting pad  670 . The user then releasably secures the valve assembly  600  to the endoscope with the strap  675 . In this embodiment, the strap  675  is about 0.5 inches and comprises hook-and-loop fasteners (here, the hooks and the loops are both on one side of the strap), and the housing  605  comprises two D-loops through which the loose ends of the strap  675  can be wrapped and secured to itself. Of course, other types of straps and securing mechanisms (e.g., gluing, stitching, riveting, ultrasonic welding, etc.) can be used.  
      In this embodiment, the surface of the mounting pad  670  that is opposite the housing  605  and faces the endoscope comprises a non-linear shape. In these drawings, the non-linear shape is a V-shape, although other non-linear shapes can be used, such as, but not limited to, a circular shape or a shape that matches a shape of a location on the endoscope to which the valve assembly  600  is to be attached. The use of a non-linear shape allows the valve assembly  600  to better grip the endoscope (or a second medical instrument or a user&#39;s hand) to prevent slippage. Preferably, the mounting pad  670  and the buckle  680  are made from a resilient material that is both flexible and tacky to (1) provide additional friction to help prevent the valve assembly  600  from slipping off the endoscope (or a second medical instrument or a user&#39;s hand), (2) provide a comfortable surface when mounted to the user&#39;s hand, and (3) prevent scratching of the endoscope or second medical instrument when mounted thereon. The non-linear shape and the resilient material also allow the valve assembly  600  to be “universal,” fitting a plurality of devices of different shapes.  
      It should be noted that these features can be used alone or in combination. For example, in one embodiment, a valve assembly can have a mounting pad (with a linear or non-linear shaped surface and/or comprising a resilient or non-resilient material), strap, and mounting buckle, while in another embodiment, a valve assembly can have a mounting pad comprising a resilient material and a non-linear shaped surface without a strap or mounting buckle.  
      Additionally, measures can be taken to prevent kinking of the first tubing  655 . During a medical procedure, a metal stopcock is often interposed between a fluid source and the first tubing  655 . The weight of the metal stopcock, as well as the weight of the fluid in the first tubing  655 , can weigh down the first tubing  655 , causing it to kink and restrict fluid flow to the input port  610 . To prevent kinking, it is presently preferred that the first tubing  655  be looped around and secured to the part of the strap  675  near the actuator  620 . This configuration is shown in  FIG. 2  of U.S. Design patent application No. ______ (attorney docket number 10672/29), filed herewith, which is assigned to the assignee of the present patent application and is hereby incorporated by reference. As an alternate kink prevention technique, the inlet port  610  can be located at the bottom of the housing  605 , thereby positioning the first tubing  655  generally in the same direction as the downward force of gravity. However, if the valve assembly  600  is secured to an endoscope or other medical instrument that is rotated during a medical procedure, the first tubing  665  can kink during rotation.  
      Table 1 lists the materials presently preferred for the components of the valve assembly  600 .  
                   TABLE 1                          Housing 605   Polycarbonate (Makrolon RX2530-1118 pre-colored           with Color Science blue)       Circular Base on the   Polycarbonate (Makrolon RX2530-1118 precolored       Housing 605 below   with Color Science blue) ultrasonically welded       the Valve Element   to the housing 605       625       Finger Pad of   Nylon (Dupont Zytel ST 801)       Actuator 620       Rotating Cuff of   Nylon (Dupont Zytel ST 801)       Actuator 620       Valve Stem 630   Polycarbonate (Makrolon RX2530-1118)       O-rings 635, 640   Medical grade Silastic silicone elastomer (Dow           Silastic Biomedical grade Elastomer Q7-4765 USP           Class VI)       Spring 645   303 Stainless Steel (spring index 10.7765, wire           diameter. 0.0149, rate 2.0 # per inch)       Mounting Pad 670   Dynaflex G2706-1000 29 Shore A thermoplastic           elastomer       Buckle 680   Dynaflex G2705-1000 58 Shore A thermoplastic           elastomer                  
 
      To improve the fluid seal and prevent fluid leaking past the first O-ring  635 , it is presently preferred that, when forming the housing  605 , the holding pressure be about 1200 psi during first-stage injection of the molding process. It was found that a holding pressure of about 1000 psi can create a “sink” condition inside the housing  605  that can allow fluid to leak past the first O-ring  635 . Sinks (i.e., features not fully formed with plastic) can occur during injection molding due to a lack of injection pressure applied during molding and/or areas within the part design that have larger than nominal wall thickness. Additionally, it is presently preferred that the o-ring cross-section and inside dimension be 0.028″×0.094″. It was found that the seal compression between the stem gland diameter and o-ring seal was better with these dimensions than with a larger o-ring having a cross-section and inside dimension of 0.030×0.098″. Further, it is presently preferred that the valve stem nominal o-ring gland outside diameter be 0.108″. It was found that an increase to this diameter from 0.099″ allowed for increased seal compression.  
      As used herein, the term “position” is intended broadly to encompass a range of positions. Thus, the valve may block fluid flow between the inlet and outlet ports in a range of blocking positions and the valve may allow fluid to flow from the inlet port to the outlet port in a range of opened positions. The valve may be configured as an on/off valve or as a modulating valve.  
      The term “handpiece” is intended broadly to refer to the part of an endoscope that carries the eyepiece and is held by the user, whether referred to as the handpiece, the bridge, or by some other term by the manufacturer of the endoscope.  
      The term “housing” is intended broadly to include one-part housings as well as housings having two or more parts that may be physically integrated with one another or spatially separated from one another.  
      The term “valve” is intended broadly to encompass valves having one or more moveable valve elements controlling the flow of one or more fluids.  
      The term “inlet port” is intended broadly to refer to a port that is connected either to a fluid source or to a suction source.  
      The term “hand” refers to any part of the user&#39;s hand, such as the palm or digits.  
      The term “digit” refers to either one of the user&#39;s four fingers or to the user&#39;s thumb.  
      Also, any suitable structure can be used for pressurizing the irrigation liquid, including simple gravity feeds in some examples.  
      The foregoing detailed description has discussed only a few of the many forms that this invention can take. This detailed description is therefore intended by way of illustration and not by way of limitation. It is only the following claims, including all equivalents, that are intended to define the scope of this invention.