Patent Publication Number: US-2023157521-A1

Title: Medical valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from U.S. Provisional Application No. 62/854,689, filed on May 30, 2019, which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to valves for medical devices, particularly endoscopes. 
     BACKGROUND 
     Endoscopes include functionality to deliver fluids (including air and water) and suction at a site of a procedure. Tubing for delivering fluids and/or suction extends from a handle of the endoscope, through a sheath of the endoscope, and to a distal tip of the endoscope. A combined air/water valve may be used to deliver air or water during the procedure. During a procedure, body fluids, tissues, or other material could enter or build up in the tubing and lead to clogging of the tubing. In order to aid in reprocessing of reusable endoscopes between procedures, pre-processing is performed in an endoscopy suite. For example, water or other fluids are flushed through the tubing after the endoscope is removed from a patient, in order to clear debris from the air/water and/or suction tubing. One option for accomplishing such pre-processing is a reusable cleaning valve. Where reusable air/water and cleaning valves are used, those valves must be subject to reprocessing between procedures. Therefore, a need exists for valves capable of delivering air/water, as well as performing cleaning functions. 
     SUMMARY 
     A valve for use in an endoscope may comprise a proximal valve stem member having a first lumen extending from a proximal opening at a proximalmost end of the proximal valve stem member to a distal opening at a distalmost end of the proximal valve stem member. A distal valve stem member may have a second lumen with a proximal opening at a proximalmost end of the distal valve stem member. The proximalmost end of distal valve stem member may be received within the distal opening of the first lumen. The distal valve stem may be movable relative to the proximal valve stem. 
     Any example of the valves described herein may additionally or alternatively include one or more of the features below. The proximal valve stem member may include a membrane within the first lumen that forms a fluid tight barrier between the proximal opening and the distal opening. In a first configuration, the proximalmost end of the distal valve stem member may be distal to an original location of the membrane so that the first lumen is not in fluid communication with the second lumen. In a second configuration, the membrane may be punctured and the proximalmost end of the distal valve stem may be proximal to the original location of the membrane so that the first lumen is in fluid communication with the second lumen. The distal valve stem member may have a shoulder that is contacted by the distalmost end of the proximal valve stem member in the second configuration. The proximal valve stem member may include a first aperture formed through a wall of the proximal valve stem member. The first aperture may be in fluid communication with the first lumen. The proximal valve stem member may include a second aperture formed through the wall of the proximal valve stem member, and wherein the second aperture is in fluid communication with the first lumen. The second lumen may be closed at a distalmost end of the second lumen. The distal valve stem member may have a third aperture formed through a wall of the distal valve stem member. The third aperture may be in fluid communication with the second lumen. The proximal valve stem member may include a button configured to be contacted by a finger of an operator. A proximal surface of the button may be at the proximalmost end of the proximal valve stem member. The proximal valve stem member may include at least one tab on a distal surface of the button. At least one seal may be disposed on an external surface of the distal valve stem member. At least two O-ring seals may be disposed on an external surface of the distal valve stem member. At least one O-ring seal may be disposed on an external surface of the proximal valve stem member. A one-way seal may be disposed on an external surface of the proximal valve stem member. The proximalmost end of the distal valve stem may be tapered. 
     In another example, a valve for use in an endoscope may comprise a proximal valve stem member having a first lumen extending from a proximal opening at a proximalmost end of the proximal valve stem member to a distal opening at a distalmost end of the proximal valve stem member. A membrane within the first lumen may form a fluid-tight barrier between the proximal opening and the distal opening. A distal valve stem member may be received within the distal opening of the first lumen. In a first configuration, the proximalmost end of the distal valve stem member may be distal to an original location of the membrane. In a second configuration, the membrane may be punctured and the proximalmost end of the distal valve stem may be proximal to the original location of the membrane. The distal valve stem member may have a second lumen with a proximal opening at a proximalmost end of the distal valve stem member. In the first configuration, the first lumen and the second lumen may not be in fluid communication. In the second configuration, the first lumen and the second lumen may be in fluid communication. 
     Any example of the valves described herein may additionally or alternatively include one or more of the features below. The second lumen may be closed at a distalmost end of the second lumen. The distal valve stem member may have an aperture formed through a wall of the distal valve stem member. The aperture may be in fluid communication with the second lumen. The proximal valve stem member may include first and second apertures through a wall of the proximal valve stem member. Each of the first and second aperture may be in fluid communication with the first lumen. 
     A method of delivering air and water may comprise: via a valve to a first configuration, delivering air to an air channel of a medical device; transitioning the valve from the first configuration to a second configuration to deliver water to a water channel of the medical device; and transitioning the valve from the second configuration to a third configuration to deliver the water to the air channel of the medical device. 
     Any method described herein may include one or more of the features or steps described below. The valve may be transitioned to the first configuration by covering a proximal hole of the valve. Transitioning the valve to the second configuration may include depressing the valve part-way. Transitioning the valve to a third configuration may include fully depressing the valve. The valve may include a proximal valve stem member having a first lumen extending from a proximal opening at a proximalmost end of the proximal valve stem member to a distal opening at a distalmost end of the proximal valve stem member. A membrane within the first lumen may form a fluid-tight barrier between the proximal opening and the distal opening. A distal valve stem member may be received within the distal opening of the first lumen. In the first and second configurations, the proximalmost end of the distal valve stem member is distal to an original location of the membrane. Transitioning from the second configuration to the third configuration may include puncturing the membrane and moving the proximalmost end of the distal valve stem to a position proximal to the original location of the membrane. 
     It may be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. The term “exemplary” is used in the sense of “example,” rather than “ideal.” As used herein, the term “proximal” means a direction closer to a surface (e.g., a button) contacted by an operator for operating a valve and the term “distal” means a direction away from the surface (e.g., a button) for operating the valve. Although endoscopes are referenced herein, reference to endoscopes or endoscopy should not be construed as limiting the possible applications of the disclosed aspects. For example, the disclosed aspects may be used with duodenoscopes, bronchoscopes, ureteroscopes, colonoscopes, catheters, diagnostic or therapeutic tools or devices, or other types of medical devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate examples of the present disclosure and together with the description, serve to explain the principles of the disclosure. 
         FIGS.  1 A- 1 C  show cross-sectional views of a first exemplary valve. 
         FIGS.  2 A- 2 C  show cross-sectional views of a second exemplary valve. 
         FIGS.  3 A- 3 B and  4 A- 4 B  show exemplary seals for use with the second exemplary valve. 
         FIGS.  5 A- 5 C  show cross-sectional views of a third exemplary valve. 
     
    
    
     DETAILED DESCRIPTION 
     A valve may be configured to both deliver air and water during a procedure and to direct a fluid for cleaning air and water channels of an endoscope following the procedure. In embodiments, the valve may be a single-use valve, and therefore disposable after only one procedure and post-procedure, although in other embodiments the valve may be reusable. The valve may have up to four or more configurations. In a first configuration, the valve may deliver neither air nor water to channels in a sheath of the endoscope. In a second configuration, the valve may only deliver air to only an air channel of the sheath. In a third configuration, the valve may deliver only water to only a water channel of the sheath. In a fourth configuration, the valve may deliver only water to both the air and the water channels in order to perform pre-processing cleaning of the air and water channels. 
       FIGS.  1 A- 1 C  show a cross-sectional view of an exemplary valve  10  in a valve cylinder  12 . Valve cylinder  12  may have surfaces  14  that define a cavity into which valve  10  may be inserted. Valve cylinder  12  may include connections to channels for inflow or outflow of air or water in a medial device, such as an endoscope. For example, valve cylinder  12  may have an air inlet  16  and an air outlet  18 . Valve cylinder  12  may also have a water inlet  20  and a water outlet  22 . From proximal to distal, the outlets may be ordered as follows: air outlet  18 , air inlet  16 , water outlet  22 , and water inlet  20 . 
     Valve  10  may have a valve stem  24 . Valve stem  24  may have a proximal member  26  and a distal member  28 . Portions of valve stem  24  including proximal member  26  and distal member  28 , may be made from metal (e.g., stainless steel, titanium, aluminum, etc.), from a polymer (e.g. polycarbonate, ABS, HDPE, Nylon, PEEK, thermoplastic, plastic, etc.), or from any other suitable material. Proximal member  26  and distal member  28  may be made from the same material or from different materials. Proximal member  26  and/or distal member  28  may be formed from a single, continuous material. 
     Proximal member  26  may include a button  32 . Button  32  may be formed as one continuous structure with the rest of proximal member  26 , or button  32  may be a separate structure attached to the rest of proximal member  26 . Button  32  may have an outer circumference that is wider than a proximal opening of valve cylinder  12 , so that when button  32  is depressed, button  32  cannot pass through the proximal opening of valve cylinder  12 . 
     Proximal member  26  may have a proximal lumen  40 . Proximal member  26  may have a generally annular shape around lumen  40 . Proximal lumen  40  may have a proximalmost opening  41  on a proximalmost end of proximal member  26 . For example, proximal lumen  40  may be open on a proximalmost side of button  32 . Proximal opening  41  is shown with dashes to indicate that, as discussed below, proximal opening  41  may be covered by an operator (e.g., by the finger or thumb of an operator). 
     As shown in  FIGS.  1 A and  1 B , a membrane  42  may extend completely across proximal lumen  40  toward a distal end  44  of proximal lumen  40 . For example, membrane  42  may be a small distance from a distalmost end of proximal lumen  40 . Alternatively, membrane  42  may be at a distalmost end of proximal lumen  40 . Membrane  42  may be formed of a thin material. Aspects of membrane  42  will be discussed in further detail with reference to  FIGS.  1 B- 1 C . 
     A proximal aperture  46  may be formed in, and extend completely through, a wall of proximal member  26  and may fluidly connect proximal lumen  40  to an area external to proximal member  26 . Although one proximal aperture  46  is shown in  FIGS.  1 A- 1 C , any number of proximal apertures may be used. One or more air apertures  48  may also be formed in, and extend completely through, a wall of proximal member  26  and may fluidly connect proximal lumen  40  to an area external to proximal member  26 . Although only one air aperture  48  is shown, any suitable number of apertures may be utilized. 
     Distal member  28  may include a neck  50  on a proximal end of distal member  28 . Neck  50  may have an outer diameter that is smaller than a diameter of lumen  40 . Neck  50  may terminate distally in a shoulder  52 . Neck  50  may have a proximal tapered portion  54 . A distal lumen  60  may pass through distal member  28 , including neck  50 . Distal lumen  60  may be open on a proximalmost side of distal member  28  (e.g., on a proximalmost end  62  of neck  50 ) and may be closed on a distalmost side of distal member  28 . A diameter of distal lumen  60  may be smaller than a diameter of proximal lumen  40 . Tapered portion  54  may taper from an initial outer diameter (at a proximal end) until its outer diameter is substantially the same as a diameter of distal lumen  60 . The proximalmost end of tapered portion  54  may form a sufficiently sharp annular ring to cut through, puncture, or otherwise remove membrane  42  under sufficient force. Portions of membrane  42  that are severed by tapered portion  54  may be flushed away by fluids flowing through valve  10  (further details of the flushing process are discussed below) or may remain within valve  10 . A distal aperture  64  may be formed in, and extend completely through, a wall of distal member  28  and may fluidly connect distal lumen  60  to an area external to distal member  28 . Although one distal aperture  64  is shown in  FIGS.  1 A- 1 C , any number of distal apertures may be used. 
     Neck  50  may be slidably received within proximal lumen  40  so that distal lumen  60  is in fluid communication with proximal lumen  40 . Proximal lumen  40  and/or neck  50  may have features (e.g., indentations, protrusions, tabs, etc.) (not shown) that retain neck  50  within lumen  40  and prevent a proximalmost end  62  of neck  50  from exiting a distalmost end  44  of proximal lumen  40 . 
     Valve stem  30  may be fitted with one or more seals. For example, valve stem  30  may include, in a direction from proximal to distal, a first seal  72 , a second seal  74 , a third seal  76 , and a fourth seal  78 . Seals  72 ,  74 ,  76 , and  78  may be, for example, O-rings. Seals  72 ,  74 ,  76 , and  78  may be formed from an elastomeric material. Valve stem  30  may also include a one-way seal  82 , which may be made of the same or different material as seals  72 ,  74 ,  76 , and  78  (e.g., an elastomeric material). One-way seal  82  may permit passage of fluid or other substances proximally past one-way seal  82  but may not permit passage of fluid or other substances distally past one-way seal  82  due to its flexibility and arrangement relative to its contacted structure. First seal  72  and second seal  74  may be disposed on proximal member  26 . Third seal  76  and fourth seal  78  may be disposed on distal member  28 . One-way seal  82  may be disposed on proximal member  26  between second seal  74  and third seal  76 . Alternatively, seals  72 ,  74 ,  76 ,  78  and one-way seal  82  may be disposed on alternative portions of valve stem  30  or in different orders. Proximal aperture  46  may be disposed between first seal  72  and second seal  74 . Distal aperture  64  may be disposed between third seal  76  and fourth seal  78 . 
     Seals  72 ,  74 ,  76 , and  78  may be configured so as to form a slidable interference fit between seals  72 ,  74 ,  76 , and  78  and surface  14 . Thus, valve stem  30  can move relative to surface  14 , but fluids (e.g. water and air) cannot move between seals  72 ,  74 ,  76 , and  78  and surface  14 . Thus, seals  72 ,  74 ,  76 , and  78  prevent movement of fluids external to valve  10  in a proximal or distal direction past seals  72 ,  74 ,  76 , and  78 . 
     An inner diameter of one-way seal  82  may be sized so that there is a slight interference between an external surface of proximal member  26  and the inner diameter of one-way seal  82 , so that a tight seal is formed. An outer diameter of one-way seal  82  may be sized so as to form a slight interference fit with a portion of surface  14 . A thin flap of one-way seal  82  may extend radially outward from proximal member  26  at an angle transverse to a longitudinal axis of proximal member  26 . For example, the thin flap may extend at an angle between 10 degrees and 80 degrees relative to a longitudinal axis of proximal member  26 . The flap of one-way seal  82  may be expandable so that when fluid (e.g., water or air) moves in a distal direction toward one-way seal  82 , a positive pressure will expand the flap, maintaining a seal between one-way seal  82  and surface  14 . Fluid moving proximally toward one-way seal  82  will also create a positive pressure, but the positive pressure will produce a force normal to a longitudinal axis of proximal member  26  to radially compress the flap of one-way seal  82 . Thus, fluid (e.g., air or water) is permitted to move proximally past one-way seal  82 , between one-way seal  82  and surface  14 . 
       FIG.  1 A  shows valve  10  in a first configuration and/or a second configuration. In the first configuration of valve  10 , neither air nor water is delivered to any outlets of valve  10  and will vent through proximalmost opening  41  to the atmosphere. 
     In the second configuration, air is delivered to an air channel of an endoscope but water is not delivered to any channel. The first configuration and second configuration may differ only in that proximalmost opening  41  at a proximalmost end of proximal lumen  40  is left open in the first configuration and is blocked (e.g., by an operator&#39;s thumb or finger) in the second configuration. In the first and second configurations, button  32  may not be pushed down. Valve  10  may include features such as tactile feedback features (not shown) to indicate that valve  10  is in a proper position within valve cylinder  12 . For example, valve  10  can include ridges, bumps, or other protrusions on an outside surface of proximal member  26 . Proximalmost end  62  of distal lumen  60  (and neck  50 ) may be distal of membrane  42  so that proximal lumen  40  is not in fluid communication with distal lumen  60 . 
     In the first and second configurations, water inlet  20  may be distal to fourth seal  78 . Water outlet  22  may be between third seal  76  and fourth seal  78 . Thus, water from water inlet  20  may not move proximally of fourth seal  78 . Water outlet  22  is surrounded by third seal  76  and fourth seal  78 , and therefore fluids (air and water) cannot move longitudinally to water outlet  22  along surfaces  14  of cylinder  12 . And because membrane  42  is in place, distal lumen  60  and proximal lumen  40  are not in fluid communication. Thus, no fluids may exit water outlet  22 . 
     In the first configuration (e.g., when proximalmost opening  41  is not covered and neither air nor water is delivered), as shown in dashed-line arrows on  FIG.  1 A , air may enter from air inlet  16 , pass proximally past one-way seal  82 , and then pass around a circumference of proximal member  26  of valve stem  24  to air aperture  48 . Air will enter air aperture  48  instead of passing out air outlet  18  because proximalmost opening  41  venting to the atmosphere provides the path of least resistance. Air may then vent proximally out of proximalmost opening  41 . Any air that would exit aperture  46  would be trapped between first seal  72  and second seal  74 , so air will instead vent from proximalmost opening  41 . Air may not travel distally past third seal  76  and thus may not exit water outlet  22 . Air inlet  16  may be proximal of third seal  76  but distal to one-way seal  82 . Though air entering from air inlet  16  could travel proximally past one-way seal  82  toward air outlet  18 , the path of least resistance will be for air to vent from proximalmost opening  41 , and therefore air will not exit air outlet  18 . Thus, in the first configuration, neither air nor water is delivered. 
     In the second configuration, also shown in  FIG.  1 A , proximalmost opening  41  may be covered by, for example, an operator&#39;s thumb or finger. Proximalmost opening  41  may also be covered in the third and fourth configurations, discussed below. Otherwise, the second configuration may be identical to the first configuration, e.g., all of the structures of valve  10  are in the same locations relative to one another and cylinder  12 . Because air can no longer vent out of proximalmost opening  41 , as shown in solid-line arrows on  FIG.  1 A , air entering from air inlet  16  may travel proximally past one-way seal  82 . Thus, air entering from air inlet  16  may pass through air outlet  18  to deliver air to an air channel of an endoscope. Air from air inlet  16  may not pass proximally of second seal  74  and thus may not enter proximal aperture  46 . air entering aperture  48  cannot exit proximalmost opening  41  as it is covered. Thus, in the second configuration, valve  10  will deliver air to an air channel of the endoscope. 
       FIG.  1 B  shows valve  10  in a third configuration, in which water is delivered to a water channel of the endoscope but air is not delivered to any endoscope channel. To transition from the second configuration to the third configuration, button  32  may be depressed part-way. For example, button  32  may be depressed until a pliable feature on a distal surface of button  32  is in contact with an outer, proximal surface of cylinder  12 . For example, tabs  94  may contact an outer surface of cylinder  12 . Contact of features such as tabs  94  may cause tactile feedback to an operator to indicate that valve  10  is in the third configuration. Tabs  94  are merely exemplary, and any suitable feature may be used. For example, an annular flap/flange, expanded inflatable features, frangible piece, or other feature may be used. Tabs  94  may be made of the same material as button  32  or from a different material. 
     In transitioning from the second configuration to the third configuration, both proximal member  26  and distal member  28  may translate distally relative to cylinder  12 , as a result of button  32  being pressed downward. Membrane  42  may be sufficiently resilient that a force on button  32  to transition valve  10  from the second configuration to the third configuration may not cause a proximalmost end of neck  50  to break through membrane  42 . Therefore, membrane  42  may remain intact in the third configuration, and a force on neck  50  from membrane  42  may cause a distal translation of distal member  28  along with proximal member  26 . Distal member  28  (and proximal member  26 ) may translate distally until distal member  28  rests on a distal surface of cylinder  12 , or until tabs  94  contact an upper, proximal surface of cylinder  12 . Additionally or alternatively, a frictional force between an outer surface of neck  50  and an inner surface of proximal lumen  40  may cause distal member  28  to move in unison with proximal member  26 . 
     In the third configuration, fourth seal  78  may be distal to water inlet  20 . Third seal  76  may be proximal of water outlet  22 . Thus, as shown in solid-line arrows, water from water inlet  20  may not move distally past fourth seal  78  but may move through water outlet  22  and through a water channel of an endoscope. Although water may move through distal aperture  64 , water may not move proximally past membrane  42 , which may be resilient enough to block proximal movement of water. Thus, water may not enter proximal lumen  40 . Water also may not move proximally past third seal  76 . One-way seal  82  may be distal to air inlet  16  so air can not pass to enter air aperture  48 . Second seal  74  may be proximal of air inlet  16 . Thus, air from air inlet  16  may not move into proximal lumen  40  through air aperture  48  or past seal  74 , thus will not exit air outlet  18 . And, because an operator&#39;s finger or thumb still covers proximalmost opening  41 , air cannot enter air aperture  48  and vent from proximalmost opening  41 . As a result, in the third configuration, the only fluid flow to the endoscope sheath is that of water through the water channel. 
     Valve  10  may be transitioned from the third configuration back to the first/second configuration. For example, valve  10  may have a spring (not shown) or other feature which biases valve  10  to the first configuration. Alternatively, valve  10  may be transitioned from the third configuration (or the first/second configuration) to the fourth configuration. 
     As shown in  FIG.  1 C , the fourth configuration facilitates flushing of water from water inlet  20  through both water outlet  22  and air outlet  18 . The fourth configuration may be referred to as the cleaning configuration of valve  10 . To move from the third configuration to the fourth configuration, button  32  may be depressed until tabs  94  are collapsed against a surface of cylinder  12 . Substantially more force may be required to transition valve  10  to the fourth configuration than to the third configuration. While button  32  is depressed part-way in the third configuration, button  32  may be fully depressed in the fourth configuration. In the fourth configuration, tabs  94  may break (e.g., by cracking off at a proximal end of tabs  94 ) or bend flat so as to be parallel with a proximal surface of button  32  and/or a proximal surface of endoscope cylinder  12 . A certain, minimum amount of force may be required to bend or break tabs  94 . 
     Because distal member  28  already rested on a distal surface of cylinder  12  in the third configuration, distal member  28  may not translate distally along with proximal member  26  when button  32  is depressed fully. Translation of proximal member  26  distally relative to distal member  28  may cause proximal tapered portion  54  to pierce membrane  42  and thereby fluidly connect distal lumen  60  and proximal lumen  40 . In the fourth configuration, proximal tapered portion  54  of distal member  28  may be proximal of the original location of membrane  42 . Therefore, as shown with solid-line arrows, in the fourth configuration of valve  10 , water may travel from water inlet  20  and out of water outlet  22 , as in the third configuration of valve  10 . However, unlike the third configuration, the fourth configuration also permits water to travel into proximal aperture  64 , through distal lumen  60 , into proximal lumen  40 , and out of proximal aperture  46 , so that water may flow between valve stem  30  and a surface of valve cylinder  12  to air outlet  18 . Because air aperture  48  may be covered by neck portion  50  in the fourth configuration, water may not pass through air aperture  48 . 
     The fourth configuration should not be used while an endoscope is inside of a body lumen of a patient. Valve  10  may contain mechanisms to prevent an operator from unintentionally transitioning valve  10  to the fourth configuration. For example, tabs  94  may provide resistance or other tactile feedback against pushing down button  32  past the third configuration. An operator may also receive tactile feedback from a distal end of distal member  28  contacting a distal surface of valve cylinder  12  in the third configuration, indicating to the operator that button  32  should not be further depressed while an endoscope is in use during a patient procedure. Additionally or alternatively, other methods may be used to prevent accidental transition of valve  10  into the fourth configuration. For example, a deformable mechanical stop may provide audible feedback (e.g., a “click” sound), valve  10  could require rotation prior to transitioning to the fourth configuration, and/or a visual indicator may provide feedback to an operator. 
     Because membrane  42  is broken in the fourth configuration, valve  10  may not again be used in any of the first, second, or third configurations. Therefore, valve  10  is a single-use valve, for use during only one pre-processing cleaning step. Alternatively, after use in one pre-processing cleaning, valve  10  could be used as only a pre-processing cleaning valve  10  without use during patient procedures. Alternatively, membrane  42  may be a strong, reusable seal that could be reset following use so that valve  10  is reusable over multiple procedures. 
     In order to make use of valve  10 , an operator may insert valve  10  into valve cylinder  12  of an endoscope prior to a procedure. During the procedure, the operator may use valve  10  in the first, second, and/or third configurations, depending on the operator&#39;s desire to make use of air or water during the procedure. Following the procedure, the endoscope may be removed from the patient for reprocessing. Button  32  may be fully depressed so that valve  10  transitions to the fourth configuration. Valve  10  may flush water through the air and water channels for a predetermined amount of time (e.g., thirty seconds). After flushing is complete, an operator could either move button  32  proximally to disable the flow of water or could simply remove valve  10  from valve cylinder  12 . Alternatively, button  32  may automatically move proximally to disable the flow of water. The endoscope would be subject to further reprocessing, and valve  10  may be disposed. 
       FIGS.  2 A- 2 C  depict configurations of another exemplary valve  100 . Although the same valve cylinder  12  is referenced herein, it will be understood that valve  100  may be used in a different valve cylinder.  FIG.  2 A  shows valve  100  in a first/second configuration,  FIG.  2 B  shows valve  100  in a third configuration, and  FIG.  2 C  shows valve  100  in a fourth configuration. Valve  100  may have a valve stem  102 . Valve stem  102  may have a proximal portion  114  and a distal portion  116 . Proximal portion  114  of valve stem  102  may include a button  120 , which may be configured to be contacted by a finger of an operator in use of valve  100 . A spring  122  may be disposed in an annular groove within button  120  and against a distally-facing surface of button  120 . When valve  100  is inserted into cylinder  12 , a distal surface of spring  122  may rest upon a proximal surface of cylinder  12 . 
     Valve stem  102  may have an air release lumen  128 . Air release lumen  128  may extend through button  120  and have a proximalmost opening  130  on a proximal surface of button  120 . Proximalmost opening  130  is shown with dashed lines to indicate that proximalmost opening  130  may be covered by an operator (e.g., by a thumb/finger of an operator). A distal end of air release lumen  128  may be open to an exterior surface of valve stem  102  via an air aperture  126 , so that air release lumen  128  is in fluid communication with an area exterior to valve stem  102 . Air release lumen  128  may extend through a longitudinal axis of valve stem  102 , such as a central longitudinal axis of valve stem  102 . 
     Valve stem  102  may also have a water lumen  134 . Water lumen  134  may extend to a distalmost end of valve stem  102  and may have a distalmost opening  135  (see  FIG.  2 C ). Water lumen  134  may have one or more water apertures  136 . Water apertures  136  may be a plurality of openings on a circumferential surface of valve stem  102 . Water lumen  134  may be in fluid communication with an area exterior to valve stem  102  via water apertures  136 . Water lumen  134  may have a distal portion  140  that is below (distal to) air aperture  126  and that extends along a central longitudinal axis of valve stem  102 . At a point distal to a distalmost end of air release lumen  128 , water lumen  134  may divert from a central longitudinal axis of valve stem  102 . A proximal portion  142  of water lumen  134  may extend along a longitudinal axis of valve stem  102  that is off-centered. As shown in  FIG.  2 A , proximal portion  142  of water lumen  134  may include a plurality of branches radially outward of a central longitudinal axis of valve stem  102  (e.g., two branches). Alternatively, a proximal portion  142  of water lumen  134  may extend annularly about air release lumen  128 . Each branch of proximal portion  142  of water lumen  134  may be in communication with a separate plurality of apertures  136 . Alternatively, apertures  136  may extend circumferentially around proximal portion  142  so that branches of proximal portion  142  share access to a set of apertures  136 . 
     A collapsible seal  160  may form an annular wall of valve stem  102  and may surround a part of distal portion  140  of water lumen  134 . Collapsible seal  160  may be formed of the same material as a remainder of valve stem  102  or from a different material. Collapsible seal  160  may be a single, unitary structure with the remainder of valve stem  102 . Alternatively, collapsible seal  160  may include separate or additional structures from the remainder of valve stem  102 . In certain examples, material of a remainder of valve stem  102  (apart from collapsible seal  160 ) may be discontinuous at a location of collapsible seal  160 , and collapsible seal  160  may be bonded to a proximal and distal portion of valve stem  102  bordering collapsible seal  160 . For example, collapsible seal  160  may be made of a flexible polymer (e.g., TPE) having appropriate properties (such as an appropriately high durometer value). Collapsible seal  160  may be bonded to portions of distal portion  116  of valve stem  102  proximal and distal of collapsible seal  160  using, for example, adhesive or another suitable method. Alternatively, a thin cylinder of metal may extend through a center of collapsible seal  160 , and collapsible seal  160  may be bonded to the thin cylinder of metal. The cylinder of metal and/or collapsible seal  160  may be bonded to portions of distal portion  116  of valve stem  102  proximal and distal of collapsible seal  160 . The thin cylinder of metal may have an interior lumen that is in fluid communication with the rest of water lumen  134 . Exemplary collapsible seals  160  are discussed in further detail below, with respect to  FIGS.  3 A- 3 B and  4 A- 4 B . A poppet valve  170  may extend within water lumen  134  and may have a proximal end at a distal inner surface of distal portion  140  distal of water lumen  134 . Poppet valve  170  may include a shaft  172  and a tapered plug  174 . Further functionality of poppet valve  170  will be described below. Shaft  172  may be fixedly attached to valve stem  102 . When a distal portion  116  of valve stem  102  is in the first, second, and third configurations, tapered plug  174  may be seated against distal portion  116 , creating a seal between mating surfaces of poppet valve  170  and distal portion  116 . When distal portion  116  of valve stem  102  Is in the fourth configuration, distal portion  116  is displaced proximally and moves away from tapered plug  174 . This displacement opens distalmost opening  135  of water lumen  134  to water inlet  20  and water outlet  22 . 
     Valve stem  102  may also be fitted with a plurality of seals. For example, valve stem  102  may include a first seal  180 , a second seal  182 , and a third seal  184 . Seals  180 ,  182 , and  184  may be disposed in grooves of valve stem  102 . Seals  180 ,  182 , and  184  may have any of the properties of seals  72 ,  74 ,  76 , or  78 , described above. Seals  180 ,  182 , and  184  may have a slidable interference fit with a surface  14  of valve cylinder  12  so that fluids (e.g., air, water) cannot move proximally or distally between seal  180 ,  182 , or  184  and the surface  14  of valve cylinder  12 . First seal  180  may be disposed proximally of water apertures  136 . Second seal  182  may be disposed distally of water apertures  136  and proximally of air aperture  126 . Third seal  184  may be disposed distally of air aperture  126  and collapsible seal  160 . Valve stem  102  may also have a one-way seal  186  that may have any of the properties of one-way seal  82 . One-way seal  186  may permit fluids (e.g., air and water) to move proximally past one-way seal  82  but not distally past one-way seal  186 . 
     Valve stem  102  may also include a plurality of coarse threads  190 . Coarse threads  190  are shown in dashed lines in  FIGS.  2 A- 2 C  because they may be on a circumferential outer surface of valve stem  102 . Coarse threads  190  may include alternative indentations and protrusions. 
       FIG.  2 A  shows valve  100  in a first and/or second configuration. In the first and second configurations, button  120  may not be depressed and spring  122  may be in a relaxed, extended state. Spring  122  may be biased to the configuration of  FIG.  2 A . First and second seals  180 ,  182  may be proximal to air outlet  18 . One-way seal  186  may be between air outlet  18  and air inlet  16 . Collapsible seal  160  may be between air inlet  16  and water outlet  22 . Third seal  184  may be proximal of water inlet  20  and distal to water outlet  22 . Poppet valve  170  may be closed (plug  174  closes opening  135 ) so that fluid cannot enter a distalmost opening  135  of water lumen  134 . 
     In a first configuration, proximalmost opening  130  may be left uncovered. Water from water inlet  20  may not move proximally past third seal  184 . Water from water inlet  20  may also not enter water lumen  134  because poppet valve  170  is closed. Therefore, water cannot exit into channels of the endoscope. As shown with dashed-line arrows, air from air inlet  16  will be drawn to air aperture  126 , through air release lumen  128  and out of proximalmost opening  130 . Air will be drawn to enter air aperture  126  instead of passing proximally of one-way seal  186  because air aperture  126  and proximalmost opening  130  provide the path of least resistance, as there is no resistance for the air to exit to atmospheric pressure. Therefore, when proximalmost opening  130  is uncovered, air incoming from air inlet  16  does not have sufficient pressure to bypass flexible seal  186 . 
     In a second configuration, air may be delivered to a body lumen of a patient during a procedure. In the second configuration, proximalmost opening  130  may be covered by, for example, a thumb or finger of an operator. Proximalmost opening  130  may also be covered in the third and fourth configurations, discussed below. Thus, as shown in solid-line arrows, air will be prevented from exiting proximalmost opening  130 . Instead, air from air inlet  16  will travel proximally past one-way seal  186  and out air outlet  18 . Air may not travel proximally past second seal  182  and may thus not exit a proximal opening of cylinder  12 . 
     To transition valve  100  to a third configuration, button  120  may be pressed distally, compressing spring  122  and moving valve stem  102  distally. In the third configuration, poppet valve  170  remains closed (plug  174  remains covering opening  135 ). Shaft  172  of poppet valve  170  may be fixedly attached to valve stem  102  at a proximal end of shaft  172 . Collapsible seal  160  may be sufficiently stiff along an axial/longitudinal direction so as to enable movement of valve stem  102  as a unit (including distal portion  116  of valve stem  102 ). First seal  180  is proximal of air outlet  18 , while second seal  182  is distal to air outlet  18 . Third seal  184  may be distal to water inlet  20 , one-way seal  186  may be distal to air inlet  16  and proximal of water outlet  22 , and collapsible seal  160  may be proximal of water outlet  22 . Therefore, as shown in solid-line arrows, water may enter from water inlet  20  and pass out of water outlet  22 , as no seals are between water inlet  20  and water outlet  22 . However, water cannot move proximally past collapsible seal  160 . Air from air inlet  16  may not move proximally of second seal  182  or one-way seal  186  to enter air aperture  126 . Thus, although proximalmost opening  130  may be covered by a finger or thumb of an operator, air may not exit air outlet  18 . Air may likewise not exit water outlet  22  because air cannot travel distally from air inlet  16  past one-way seal  186 . 
     Valve  100  may be transitioned back to the first or second configuration by releasing pressure on button  120 . Spring  122  may be biased to an expanded state of the first configuration. Thus, button  120  may move proximally to the position of the first/second configurations when button  120  is released. 
     To transition valve  100  to a fourth configuration, button  120  (and valve stem  102 ) may be rotated in a counter-clockwise direction, which may engage coarse threads  190  and cause a distal portion  116  of valve stem  102  to be pulled upward. Coarse threads  190  may be operative (via, e.g., an internal mechanism) to pull upward on distal portion  116  of valve stem  102 . Upward motion of distal portion  116  may cause collapsible seal  160  to collapse. Collapse of collapsible seal  160  may cause poppet valve  170  to open (unseat from opening  135 ). In an alternative embodiment, rotating button  120  may open a valve that ports air pressure from air inlet  16  to a distalmost chamber in valve  100 , distal to poppet valve  170  and the distal portion  116  of valve stem  102 . This action may drive the distal portion  116  of valve stem  102  proximally, compressing collapsible seal  160  and opening water channel  134  to water inlet  20 . Alternatively to poppet valve  170 , a porous elastomer seal may be used. When the porous elastomer is relaxed (e.g., in configurations 1-3 of  FIGS.  2 A and  2 B ), the pores may be closed, and fluid may not pass the porous seal. When the seal is stretched, such as in the fourth configuration of  FIG.  2 C , the pores will be opened and fluids such as water may pass through the porous elastomer seal. 
     In the fourth configuration, third seal  184  may be aligned with water inlet  20 . Collapsible seal  160  may remain proximal of water outlet  22 . One-way seal  186  may remain distal to air inlet  16 , and second seal  182  may remain distal to air outlet  18 . First seal  180  may be proximal of air outlet  18 . Thus, as shown in solid-line arrows, water from water inlet  20  may move distally toward distalmost opening  135  of water lumen  134 . Because poppet valve  170  is open, water may enter water lumen  134  and travel proximally through water lumen  134  and through water apertures  136 . Water may then move between an outer circumference of valve stem  102  and a surface of valve cylinder  12  and out air outlet  18 . Water may also move proximally of water inlet  20  and to water outlet  22 . Thus, in the fourth configuration, water may flush the air and water channels of an endoscope. 
     Collapsing of collapsible seal  160  may be a non-reversible process. Thus, after collapsible seal  160  is transitioned to the fourth configuration, it may not be transitioned back to the first, second, or third configuration. 
     In order to make use of valve  100 , an operator may insert valve  100  into valve cylinder  12  of an endoscope prior to a procedure. During the procedure, the operator may use valve  100  in the first, second, and/or third configurations, depending on the operator&#39;s desire to make use of air or water during the procedure. Following the procedure, after the endoscope is removed from the patient for reprocessing, button  120  may be rotated so that valve  100  transitions to the fourth configuration. Valve  100  may flush water through the air and water channels for a predetermined amount of time (e.g., thirty seconds). After flushing is complete, an operator could shut off an air and water supply to disable the flow of air and water or could simply remove valve  100  from valve cylinder  12 . The endoscope would be subject to further processing, and valve  100  would be disposed. 
       FIGS.  3 A and  3 B  show an exemplary first collapsible seal  200 , which may be used with valve  100 . Collapsible seal  200  may be constructed of a flexible material, such as an elastomeric material or flexible polymer such as TPE.  FIG.  3 A  shows collapsible seal  200  in a first, closed configuration.  FIG.  3 B  shows collapsible seal  200  in a second, open configuration. In the closed configuration of  FIG.  3 A , an annular wall  202  of collapsible seal  200  projects inward into a central lumen  204  of collapsible seal  200 . Contact between annular walls  202  in central lumen  204  prevents fluid (e.g., water) from passing through central lumen  204 . 
     Collapsible seal  200  may be transitioned to the open configuration by inflating valve  200  using a fluid such as water or air. Air may be ported from air inlet  16  and actuated by a twist or push motion on the proximal end of a valve employing collapsible seal  200 . In the second configuration, wall  202  of collapsible seal  200  expands so that inner surfaces of wall  202  may be separated from one another and so that central lumen  204  is open and passible to fluid such as water. A circumferential outer surface of wall  202  may have a feature  206  (e.g., a protrusion), which causes walls  202  to engage with an inner surface of cylinder  12  and to block flow of fluid proximally past an outer surface of collapsible seal  200 . 
       FIGS.  4 A and  4 B  show another exemplary collapsible seal  300 . Collapsible seal  300  may be formed of a rigid or semi-rigid material such as plastic or metal. Collapsible seal  300  may have a plurality of longitudinal slots  302  formed around a circumferential surface of collapsible seal  300 . Longitudinal slots  302  may be covered by a material such as an elastomer (not shown) to make them impervious to fluids such as water and air. In the first configuration of collapsible seal  300 , shown in  FIG.  4 A , an outer surface of collapsible seal  300  including slots  302  may be relatively parallel with a longitudinal axis of collapsible seal  300 . 
     In  FIG.  4 B , collapsible seal  300  has transitioned to a second configuration via, e.g., the mechanisms described above for transitioning valve  100  to the fourth configuration of  FIG.  2 C . In the second configuration, an annular wall of collapsible seal  300  bulges outward due to flexibility imparted by slots  302 . An exterior, circumferential surface of the wall of collapsible seal  300  may make contact with the walls of valve cylinder  12 , barring passage of fluid, such as water, proximally past an exterior of collapsible seal  300 . However, fluids such as water may travel proximally through a distal opening of collapsible seal  300  and through a central lumen of collapsible seal  300 . 
       FIGS.  5 A- 5 C  show a cross-sectional view of an exemplary valve  500  in valve cylinder  12 . Valve  500  may have a valve stem  524 . Valve stem  524  may have a proximal member  526  and a distal member  528 . Portions of valve stem  524  including proximal member  526  and distal member  528 , may be made from metal (e.g., stainless steel, titanium, aluminum, etc.), from a polymer (e.g. polycarbonate, ABS, HDPE, Nylon, PEEK, thermoplastic, plastic, etc.), or from any other suitable material. Proximal member  526  and distal member  528  may be made from the same material or from different materials. Proximal member  526  and/or distal member  528  may be formed from a single, continuous material. 
     Proximal member  526  may include a button  532 . Button  532  may be formed as one continuous structure with the rest of proximal member  526 , or button  532  may be a separate structure attached to the rest of proximal member  526 . Button  532  may have an outer circumference that is wider than a proximal opening of valve cylinder  12 , so that when button  532  is depressed, button  532  cannot pass through the proximal opening of valve cylinder  12 . 
     Proximal member  526  may have a proximal lumen  540 . Proximal member  526  may have a generally annular shape around lumen  540 . Proximal lumen  540  may have a proximalmost opening  541  on a proximalmost end of proximal member  526 . For example, proximal lumen  540  may be open on a proximalmost side of button  532 . Proximal opening  541  is shown with dashes to indicate that, as discussed below, proximal opening  541  may be covered by an operator (e.g., by the finger or thumb of an operator). 
     As shown in  FIGS.  5 A and  5 B , a membrane  542  may extend completely across proximal lumen  540  toward a distal end  544  of proximal lumen  540 . For example, membrane  542  may be a small distance from a distalmost end of proximal lumen  540 . Alternatively, membrane  542  may be at a distalmost end of proximal lumen  540 . Membrane  542  may be formed of a thin material. Aspects of membrane  542  will be discussed in further detail with reference to  FIGS.  5 B- 5 C . 
     A proximal aperture  546  may be formed in, and extend completely through, a wall of proximal member  526  and may fluidly connect proximal lumen  540  to an area external to proximal member  526 . Although one proximal aperture  546  is shown in  FIGS.  5 A- 5 C , any number of proximal apertures may be used. One or more air apertures  548  may also be formed in, and extend completely through, a wall of proximal member  526  and may fluidly connect proximal lumen  540  to an area external to proximal member  526 . Although only one air aperture  548  is shown, any suitable number of apertures may be utilized. 
     Distal member  528  may include a neck  550  on a proximal end of distal member  528 . Neck  550  may have an outer diameter that is smaller than a diameter of lumen  540 . Neck  550  may terminate distally in a shoulder  552 . Neck  550  may have a proximal tapered portion  554 . A distal lumen  560  may pass through distal member  528 , including neck  550 . Distal lumen  560  may be open on a proximalmost side of distal member  528  (e.g., on a proximalmost end  562  of neck  550 ) and may be closed on a distalmost side of distal member  528 . A diameter of distal lumen  560  may be smaller than a diameter of proximal lumen  540 . Tapered portion  554  may taper from an initial outer diameter (at a proximal end) until its outer diameter is substantially the same as a diameter of distal lumen  560 . The proximalmost end of tapered portion  554  may form a sufficiently sharp annular ring to cut through, puncture, or otherwise remove membrane  542  under sufficient force. Portions of membrane  542  that are severed by tapered portion  554  may be flushed away by fluids flowing through valve  510  (further details of the flushing process are discussed below) or may remain within valve  510 . A distal aperture  564  may be formed in, and extend completely through, a wall of distal member  528  and may fluidly connect distal lumen  560  to an area external to distal member  528 . Although one distal aperture  564  is shown in  FIGS.  5 A- 5 C , any number of distal apertures may be used. 
     Neck  550  may be slidably received within proximal lumen  540  so that distal lumen  60  is in fluid communication with proximal lumen  540 . Proximal lumen  540  and/or neck  550  may have features (e.g., indentations, protrusions, tabs, etc.) (not shown) that retain neck  550  within lumen  540  and prevent a proximalmost end  562  of neck  550  from exiting a distalmost end  544  of proximal lumen  540 . 
     Valve stem  530  may be fitted with one or more seals. For example, valve stem  530  may include, in a direction from proximal to distal, a first seal  572 , a second seal  574 , a third seal  576 , and a fourth seal  578 . Seals  572 ,  574 ,  576 , and  578  may be, for example, O-rings. Seals  572 ,  574 ,  576 , and  578  may be formed from an elastomeric material. Valve stem  530  may also include a one-way seal  582 , which may be made of the same or different material as seals  572 ,  574 ,  576 , and  578  (e.g., an elastomeric material). One-way seal  582  may permit passage of fluid or other substances proximally past one-way seal  582  but may not permit passage of fluid or other substances distally past one-way seal  582  due to its flexibility and arrangement relative to its contacted structure. First seal  572  and second seal  574  may be disposed on proximal member  526 . Third seal  576  and fourth seal  578  may be disposed on distal member  528 . One-way seal  582  may be disposed on proximal member  526  between second seal  574  and third seal  576 . Alternatively, seals  572 ,  574 ,  576 ,  578  and one-way seal  582  may be disposed on alternative portions of valve stem  530  or in different orders. Proximal aperture  546  may be disposed between first seal  572  and second seal  574 . Distal aperture  564  may be disposed between third seal  576  and fourth seal  578 . 
     Seals  572 ,  574 ,  576 , and  578  may be configured so as to form a slidable interference fit between seals  572 ,  574 ,  576 , and  578  and surface  14 . Thus, valve stem  530  can move relative to surface  14 , but fluids (e.g. water and air) cannot move between seals  572 ,  574 ,  576 , and  578  and surface  14 . Thus, seals  572 ,  574 ,  576 , and  578  prevent movement of fluids external to valve  10  in a proximal or distal direction past seals  572 ,  574 ,  576 , and  578 . 
     An inner diameter of one-way seal  582  may be sized so that there is a slight interference between an external surface of proximal member  526  and the inner diameter of one-way seal  582 , so that a tight seal is formed. An outer diameter of one-way seal  582  may be sized so as to form a slight interference fit with a portion of surface  14 . A thin flap of one-way seal  582  may extend radially outward from proximal member  526  at an angle transverse to a longitudinal axis of proximal member  526 . For example, the thin flap may extend at an angle between 10 degrees and 80 degrees relative to a longitudinal axis of proximal member  526 . The flap of one-way seal  582  may be expandable so that when fluid (e.g., water or air) moves in a distal direction toward one-way seal  582 , a positive pressure will expand the flap, maintaining a seal between one-way seal  582  and surface  14 . Fluid moving proximally toward one-way seal  582  will also create a positive pressure, but the positive pressure will produce a force normal to a longitudinal axis of proximal member  526  to radially compress the flap of one-way seal  582 . Thus, fluid (e.g., air or water) is permitted to move proximally past one-way seal  582 , between one-way seal  582  and surface  14 . Whereas one-way seal  82  of valve  10  may be disposed distally of air aperture  48 , one-way seal  582  of valve  510  may be disposed proximally of air aperture  548 . 
       FIG.  5 A  shows valve  510  in a first configuration and/or a second configuration. In the first configuration of valve  510 , neither air nor water is delivered to any outlets of valve  510  and will vent through proximalmost opening  541  to the atmosphere. 
     In the second configuration, air is delivered to an air channel of an endoscope but water is not delivered to any channel. The first configuration and second configuration may differ only in that proximalmost opening  541  at a proximalmost end of proximal lumen  540  is left open in the first configuration and is blocked (e.g., by an operator&#39;s thumb or finger) in the second configuration. In the first and second configurations, button  532  may not be pushed down. Valve  510  may include features such as tactile feedback features (not shown) to indicate that valve  510  is in a proper position within valve cylinder  12 . For example, valve  510  can include ridges, bumps, or other protrusions on an outside surface of proximal member  526 . Proximalmost end  562  of distal lumen  560  (and neck  550 ) may be distal of membrane  542  so that proximal lumen  540  is not in fluid communication with distal lumen  560 . 
     In the first and second configurations, water inlet  20  may be distal to fourth seal  578 . Water outlet  22  may be between third seal  576  and fourth seal  578 . Thus, water from water inlet  20  may not move proximally of fourth seal  578 . Water outlet  22  is surrounded by third seal  576  and fourth seal  578 , and therefore fluids (air and water) cannot move longitudinally to water outlet  22  along surfaces  14  of cylinder  12 . And because membrane  542  is in place, distal lumen  560  and proximal lumen  540  are not in fluid communication. Thus, no fluids may exit water outlet  22 . 
     In the first configuration (e.g., when proximalmost opening  541  is not covered and neither air nor water is delivered), as shown in dashed-line arrows on  FIG.  5 A , air may enter from air inlet  16  and then pass around a circumference of proximal member  526  of valve stem  524  to air aperture  548 . Air will enter air aperture  548  instead of passing out air outlet  18  because proximalmost opening  541  venting to the atmosphere provides the path of least resistance. Air may then vent proximally out of proximalmost opening  541 . Any air that would exit aperture  546  would be trapped between first seal  572  and second seal  574 , so air will instead vent from proximalmost opening  541 . Air may not travel distally past third seal  576  and thus may not exit water outlet  522 . Air inlet  516  may be proximal of third seal  576  but distal to one-way seal  582 . Air entering from air inlet  16  will not travel proximally past one-way seal  582  toward air outlet  18 , because the path of least resistance will be for air to vent from proximalmost opening  541 , and therefore air will not exit air outlet  18 . Thus, in the first configuration, neither air nor water is delivered. 
     In the second configuration, also shown in  FIG.  5 A , proximalmost opening  541  may be covered by, for example, an operator&#39;s thumb or finger. Proximalmost opening  541  may also be covered in the third and fourth configurations, discussed below. Otherwise, the second configuration may be identical to the first configuration, e.g., all of the structures of valve  510  are in the same locations relative to one another and cylinder  12 . Because air can no longer vent out of proximalmost opening  541 , as shown in solid-line arrows on  FIG.  1 A , air entering from air inlet  16  may travel proximally past one-way seal  582 . Thus, air entering from air inlet  16  may pass through air outlet  18  to deliver air to an air channel of an endoscope. Air from air inlet  16  may not pass proximally of second seal  574  and thus may not enter proximal aperture  546 . Air entering aperture  548  cannot exit proximalmost opening  541  as it is covered. Thus, in the second configuration, valve  510  will deliver air to an air channel of the endoscope. 
       FIG.  5 B  shows valve  510  in a third configuration, in which water is delivered to a water channel of the endoscope but air is not delivered to any endoscope channel. To transition from the second configuration to the third configuration, button  532  may be depressed part-way. For example, button  532  may be depressed until a pliable feature on a distal surface of button  532  is in contact with an outer, proximal surface of cylinder  12 . For example, tabs  594  may contact an outer surface of cylinder  12 . Contact of features such as tabs  594  may cause tactile feedback to an operator to indicate that valve  10  is in the third configuration. Tabs  594  are merely exemplary, and any suitable feature may be used. For example, an annular flap/flange, expanded inflatable features, frangible piece, or other feature may be used. Tabs  594  may be made of the same material as button  532  or from a different material. 
     In transitioning from the second configuration to the third configuration, both proximal member  526  and distal member  528  may translate distally relative to cylinder  512 , as a result of button  532  being pressed downward. Membrane  542  may be sufficiently resilient that a force on button  532  to transition valve  510  from the second configuration to the third configuration may not cause a proximalmost end of neck  550  to break through membrane  542 . Therefore, membrane  542  may remain intact in the third configuration, and a force on neck  550  from membrane  542  may cause a distal translation of distal member  528  along with proximal member  526 . Distal member  528  (and proximal member  526 ) may translate distally until distal member  528  rests on a distal surface of cylinder  12 , or until tabs  594  contact an upper, proximal surface of cylinder  12 . Additionally or alternatively, a frictional force between an outer surface of neck  550  and an inner surface of proximal lumen  540  may cause distal member  528  to move in unison with proximal member  526 . 
     In the third configuration, fourth seal  578  may be distal to water inlet  20 . Third seal  576  may be proximal of water outlet  22 . Thus, as shown in solid-line arrows, water from water inlet  20  may not move distally past fourth seal  578  but may move through water outlet  22  and through a water channel of an endoscope. Although water may move through distal aperture  564 , water may not move proximally past membrane  542 , which may be resilient enough to block proximal movement of water. Thus, water may not enter proximal lumen  540 . Water also may not move proximally past third seal  576 . One-way seal  582  may be distal to air inlet  16  so air can not pass to enter air aperture  548 . Second seal  574  may be proximal of air inlet  16 . Thus, air from air inlet  16  may not move into proximal lumen  540  through air aperture  548  or past seal  574 , thus will not exit air outlet  18 . As a result, in the third configuration, the only fluid flow to the endoscope sheath is that of water through the water channel. 
     Valve  510  may be transitioned from the third configuration back to the first/second configuration. For example, valve  510  may have a spring (not shown) or other feature which biases valve  510  to the first configuration. Alternatively, valve  510  may be transitioned from the third configuration (or the first/second configuration) to the fourth configuration. 
     As shown in  FIG.  5 C , the fourth configuration facilitates flushing of water from water inlet  20  through both water outlet  22  and air outlet  18 . The fourth configuration may be referred to as the cleaning configuration of valve  510 . To move from the third configuration to the fourth configuration, button  532  may be depressed until tabs  594  are collapsed against a surface of cylinder  12 . Substantially more force may be required to transition valve  150  to the fourth configuration than to the third configuration. While button  532  is depressed part-way in the third configuration, button  532  may be fully depressed in the fourth configuration. In the fourth configuration, tabs  594  may break (e.g., by cracking off at a proximal end of tabs  594 ) or bend flat so as to be parallel with a proximal surface of button  532  and/or a proximal surface of endoscope cylinder  12 . A certain, minimum amount of force may be required to bend or break tabs  94 . 
     Because distal member  528  already rested on a distal surface of cylinder  12  in the third configuration, distal member  528  may not translate distally along with proximal member  526  when button  532  is depressed fully. Translation of proximal member  526  distally relative to distal member  528  may cause proximal tapered portion  554  to pierce membrane  542  and thereby fluidly connect distal lumen  560  and proximal lumen  540 . In the fourth configuration, proximal tapered portion  554  of distal member  528  may be proximal of the original location of membrane  542 . Therefore, as shown with solid-line arrows, in the fourth configuration of valve  510 , water may travel from water inlet  20  and out of water outlet  22 , as in the third configuration of valve  510 . However, unlike the third configuration, the fourth configuration also permits water to travel into proximal aperture  564 , through distal lumen  560 , into proximal lumen  540 , and out of proximal aperture  546 , so that water may flow between valve stem  530  and a surface of valve cylinder  12  to air outlet  18 . Because air aperture  548  may be covered by neck portion  550  in the fourth configuration, water may not pass through air aperture  548 . 
     The fourth configuration should not be used while an endoscope is inside of a body lumen of a patient. Valve  510  may contain mechanisms to prevent an operator from unintentionally transitioning valve  510  to the fourth configuration. For example, tabs  594  may provide resistance or other tactile feedback against pushing down button  532  past the third configuration. An operator may also receive tactile feedback from a distal end of distal member  528  contacting a distal surface of valve cylinder  12  in the third configuration, indicating to the operator that button  532  should not be further depressed while an endoscope is in use during a patient procedure. Additionally or alternatively, other methods may be used to prevent accidental transition of valve  510  into the fourth configuration. For example, a deformable mechanical stop may provide audible feedback (e.g., a “click” sound), valve  510  could require rotation prior to transitioning to the fourth configuration, and/or a visual indicator may provide feedback to an operator. 
     Because membrane  542  is broken in the fourth configuration, valve  510  may not again be used in any of the first, second, or third configurations. Therefore, valve  510  is a single-use valve, for use during only one pre-processing cleaning step. Alternatively, after use in one pre-processing cleaning, valve  510  could be used as only a pre-processing cleaning valve  510  without use during patient procedures. Alternatively, membrane  542  may be a strong, reusable seal that could be reset following use so that valve  510  is reusable over multiple procedures. 
     In order to make use of valve  510 , an operator may insert valve  510  into valve cylinder  12  of an endoscope prior to a procedure. During the procedure, the operator may use valve  510  in the first, second, and/or third configurations, depending on the operator&#39;s desire to make use of air or water during the procedure. Following the procedure, the endoscope may be removed from the patient for reprocessing. Button  532  may be fully depressed so that valve  510  transitions to the fourth configuration. Valve  510  may flush water through the air and water channels for a predetermined amount of time (e.g., thirty seconds). After flushing is complete, an operator could either move button  532  proximally to disable the flow of water or could simply remove valve  510  from valve cylinder  12 . Alternatively, button  532  may automatically move proximally to disable the flow of water. The endoscope would be subject to further reprocessing, and valve  510  may be disposed. 
     While principles of the present disclosure are described herein with reference to illustrative examples for particular applications, it should be understood that the disclosure is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and substitution of equivalents all fall within the scope of the examples described herein. Accordingly, the invention is not to be considered as limited by the foregoing description.