Patent Publication Number: US-7914439-B2

Title: Implantable penile prosthesis pump

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 11/305,672, filed Dec. 16, 2005 now U.S. Pat. No. 7,637,861, which claims the benefit of U.S. provisional patent application No. 60/637,032, filed Dec. 17, 2004, entitled “Side Squeeze Momentary Squeeze Pump,” the entire disclosures of which are incorporated herein by reference for all purposes. 
    
    
     TECHNICAL FIELD 
     The invention relates to systems for treating erectile dysfunction and other urological disorders. In particular, the invention relates to pumps for use with inflatable implantable penile prostheses. 
     BACKGROUND 
     One common treatment for male erectile dysfunction is the implantation of a penile prosthesis. Such a prosthesis typically includes a pair of inflatable cylinders, which are fluidly connected to a reservoir via a pump and valve assembly. The two cylinders are normally implanted into the corpus cavernosae of the patient and the reservoir is typically implanted into the patient&#39;s abdomen. The pump assembly is implanted in the scrotum. 
     During use, the patient actuates the pump and fluid is transferred from the reservoir through the pump and into the cylinders. This results in the inflation of the cylinders and thereby produces the desired penis rigidity for a normal erection. Then, when the patient desires to deflate the cylinders, a valve assembly within the pump is actuated in a manner such that the fluid in the cylinders is released back into the reservoir. This deflation then returns the penis to a flaccid state. 
     Presently, the pump and valve assembly used in such implantable prostheses share certain similar characteristics. For example, they include fluid pathways allowing the flow of fluid to and from the reservoir, as well as to and from the cylinders. In some designs this fluid flow is controlled by one or more poppet valves positioned in such fluid pathways within the housing of the assembly. 
     A compressible pump bulb is also attached to the housing and is in fluid communication with the various fluid pathways. In order to inflate the cylinders, the compressible pump bulb is actuated by the patient, thereby urging fluid in the bulb past the poppet valves into the cylinders. In order to deflate the cylinders, the valve housing is grasped and squeezed, through the patient&#39;s tissue, causing the various poppet valves to unseat and allow fluid to flow back to the reservoir. 
     SUMMARY 
     Pumps for use with inflatable penile prostheses in accordance with the invention can be designed to include advantageous features such as the ability to functionally arrange valve components in a compact manner and different alignment between functional valve components. 
     In one aspect of the invention, a pump that provides a feature that allows a free path for fluid flow under certain conditions is provided. The pump preferably comprises a pump housing, first and second fluid ports, and a pump bulb. The pump housing comprises a fluid passageway. The first and second fluid ports are in fluid communication with the fluid passageway and are operatively connectable to a fluid reservoir and at least one inflatable penile prosthesis, respectively. The pump bulb is in fluid communication with the fluid passageway and can be operated to transfer fluid between the first and second fluid ports through the fluid passageway. The pump comprises a poppet positioned within the fluid passageway. The poppet includes an extending portion extending away from a body portion of the poppet. The extending portion has a sealing surface biased toward a valve seat within the fluid passageway. The pump includes a flange extending from a surface of the fluid passageway and toward the interior of the fluid passageway and spaced from the valve seat within the fluid passageway. One or more of the flange and the extending portion of the poppet may include one or more protrusions that provide a gap between the flange and extending portion of the poppet. In one embodiment of a refill phase of pumping, a fluid path is established between the extending portion of the poppet and the flange when the extending portion of the poppet is in contact with the flange so that fluid can pass from one side of the flange to the other. 
     In another aspect of the invention, a pump with slidingly engaged poppets is provided. The pump preferably comprises a pump housing, first and second fluid ports, and a pump bulb. The pump housing comprises a fluid passageway. The first and second fluid ports are in fluid communication with the fluid passageway and are operatively connectable to a fluid reservoir and at least one inflatable penile prosthesis, respectively. The pump bulb is in fluid communication with the fluid passageway and can be operated to transfer fluid between the first and second fluid ports through the fluid passageway. The pump includes first and second poppets positioned within the fluid passageway and biased toward first and second valve seats within the fluid passageway, respectively. The first poppet comprises an end slidingly engaged with an end of the second poppet. 
     In yet another aspect of the invention a pump having a bypass chamber is provided. The pump preferably comprises a pump housing, first and second fluid ports, and a pump bulb. The pump housing comprises a fluid passageway. The first and second fluid ports are in fluid communication with the fluid passageway and are operatively connectable to a fluid reservoir and at least one inflatable penile prosthesis, respectively. The pump bulb is in fluid communication with the fluid passageway and can be operated to transfer fluid between the first and second fluid ports through the fluid passageway. First and second poppets are positioned within the fluid passageway, aligned along a poppet valve axis, and biased toward first and second valve seats within the fluid passageway, respectively. The bypass chamber is fluidly connected by a bypass input channel to the fluid passageway at a first location and fluidly connected by a bypass output channel to the fluid passageway at a second location. The bypass chamber comprises a bypass check valve biased toward a closed position along a check valve axis. The check valve axis is oriented in a non-parallel manner with respect to the valve axis of the first and second poppets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein: 
         FIG. 1  is a perspective view of a pump assembly that can be used with an inflatable implantable penile prostheses in accordance with the invention; 
         FIG. 2  is a side view of the pump assembly illustrated in  FIG. 1 ; 
         FIG. 3  is bottom view of the pump assembly illustrated in  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the pump assembly illustrated in  FIG. 3 , taken along the line  4 - 4 ; 
         FIG. 5  is a cross-sectional view of the pump assembly illustrated in  FIG. 4 , taken along the line  5 - 5 ; 
         FIG. 6  is a cross-sectional view of the pump assembly illustrated in  FIG. 2 , taken along the line  6 - 6 ; 
         FIG. 7  is a cross-sectional view of the pump assembly illustrated in  FIG. 4 , taken along the line  7 - 7 ; 
         FIG. 8  is a cross-sectional view of the pump assembly illustrated in  FIG. 5 , taken along the line  8 - 8 ; 
         FIG. 9  is a cross-sectional view of the pump assembly illustrated in  FIG. 5 , taken along the line  9 - 9 ; 
         FIG. 10  is a cross-sectional view of another embodiment of a pump assembly of the invention; 
         FIG. 11  is a cross-sectional view of the pump assembly of  FIG. 10  taken along the line  11 - 11 ; 
         FIG. 12  illustrates a schematic perspective view of an implantable penile prosthesis device having a pump assembly of the type illustrated in  FIGS. 1 through 11 ; and 
         FIG. 13  is another cross-sectional view of the pump assembly illustrated in  FIG. 6 , with the internal components configured in a different operating condition of the pump. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 through 9  and  13 , pump assembly  10  for use in an implantable penile prosthesis system is illustrated. In  FIGS. 1 through 3 , a perspective, side, and bottom view of the pump assembly  10  are shown, respectively. In  FIGS. 4 through 9  and  13 , various cross-sectional views of the pump assembly  10  are shown to illustrate its various functional aspects and components. In general, when a penile prosthesis system is implanted into a person, a pump assembly, such as pump assembly  10 , is positioned within the user&#39;s scrotum, two inflatable cylinders are positioned within the user&#39;s corpus cavernosae and a reservoir is implanted in the user&#39;s abdomen. One or more tubes provide fluid communication between assembly  10  and the cylinders and between assembly  10  and the reservoir. In this embodiment, assembly  10  includes housing or pump body  12  connected to pump bulb  14  having an internal chamber  16 . Pump assembly  10  is connected for fluid communication with at least one inflatable cylinder (not shown) by ports  20  and  21 , which preferably comprise flexible silicone tubes. Alternatively, pump assembly  10  can be designed with a single port that comprises a single tube that could be fluidly connected directly to pump assembly  10  and branch into multiple tubes that extend to each of the cylinders at some distance from pump assembly  10 . Any such tube is preferably relatively flexible for comfort and conformability within a patient, and may have a constant or varying (e.g., tapered) diameter along its length. 
     Pump assembly  10  is further connected for fluid communication with at least one fluid-filled reservoir (not shown) by at least one reservoir port  18  that preferably comprises a flexible silicone tube as shown. While only one port is used in the embodiment shown in  FIG. 1 , assembly  10  may include additional ports for connection to one or more reservoirs, or a single port may be fluidly connected to pump assembly  10  with a tube that branches into multiple tubes that connect to one or more reservoirs. In the preferred embodiment, however, port  18  is provided to fluidly connect pump assembly  10  to a single reservoir, which is typically implanted in the abdomen or some other location in the user&#39;s body that is spaced from pump assembly  10 . Any such tube used with port  18  is preferably made of a relatively flexible material, such as silicone, and is sufficiently long for connecting the reservoir to the pump body when these components are implanted in their desired locations in the body. 
     Pump assembly  10  of the invention is controllable by the user to move fluid to and from the inflatable cylinders, as desired. Importantly, pump assembly  10  preferably includes features that can eliminate or reduce the possibility of a vacuum lock that can interrupt the inflation process as described in more detail below. Preferably, pump assembly  10  also includes poppets that slidingly engage to provide an alignment feature for such poppets in the pump assembly. In addition, pump assembly  10  is preferably configured so that poppet valve components of pump assembly  10  are provided along a short axis of pump body  12 . In this way, a stable platform for the user&#39;s fingers to hold onto the pump assembly and squeeze for deflation is provided. Thus, pump assembly  10  provides a reliable controllable device that is easily manipulated by the user to inflate and deflate the cylinders, as desired. 
     Pump body  12  preferably comprises a generally flexible device that includes a number of components to provide the desired movement of fluid through its internal chambers. Reservoir port  18  is fluidly connected to transfer chamber  22  within pump body  12 . As can be seen best in the section view of  FIG. 8 , transfer chamber  22  is fluidly connected to annular channel  68  and radial channels  70 ,  72 , and  74 . Transfer chamber  22  can also fluidly communicate with ports  20  and  21  through connecting fluid passageway  24  (see  FIGS. 4 and 5 , for example). Fluid passageway  24  is further connected to internal chamber  16  of pump bulb  14  by connecting channel  26  (see  FIG. 5 ), where the various fluidic connections can be initiated and terminated with the operation of pump assembly  10 , as described below. As shown in  FIG. 6 , for example, fluid passageway  24  is a generally elongated chamber that extends across a portion of width  25  of pump body  12  and provides a passageway through which fluid can flow between the components of pump assembly  10 , such as a reservoir, internal chamber  16 , fluid bypass chamber  46 , and cylinders. 
     Referring particularly to  FIG. 6 , fluid passageway  24  includes within its internal area a check valve system that generally includes reservoir poppet  28  and cylinder poppet  36 . Reservoir poppet  28  and cylinder poppet  36  are preferably coaxially aligned with each other on a poppet valve axis  23  along the length of passageway  24 , with both poppets preferably being centrally positioned within passageway  24 . Reservoir poppet  28  has a generally elongated shape and is designed for contact and sealing with various components of the system during its operation. In particular, reservoir poppet  28  includes elongated body  29  that is preferably generally cylindrical, as shown, although it can take any number of shapes that fit within the internal chamber of fluid passageway  24  to provide contact with its surfaces and control the movement of fluid. Reservoir poppet  28  further includes face seal portion  30  that is preferably a ring-like protrusion that extends around the outer perimeter of elongated body  29 . As shown, face seal portion  30  is positioned near the center of the length of elongated body  29 , although it is possible that portion  30  is closer to one of the ends of elongated body  29  than its other end. Face seal portion  30  includes a sealing surface  33  for providing a seal with a surface  35  of valve seat  34  when pump assembly  10  is configured for filling of an implantable cylinder. Face seal portion  30  also includes chamfer  31  for providing a seal with flange  44  when pump assembly  10  is configured for deflation of an implantable cylinder. Surface  35  of valve seat  34  that contacts surface  33  of face seal portion  30  is preferably a generally smooth surface that allows for a fluid tight seal between surface  33  of face seal portion  30  and surface  35  of valve seat  34 , when such sealing is desired. A spring  32  engages reservoir poppet  28  and biases reservoir poppet  28  toward valve seat  34 . 
     Fluid passageway  24  further includes flange  44  configured generally as a ring-like portion within passageway  24  that preferably extends toward the center of passageway  24  around the inner perimeter of fluid passageway  24 . Flange  44  is provided to reduce the inner diameter of passageway  24  by a sufficient amount so that the inner diameter in the area of flange  44  is smaller than the outer diameter of face seal portion  30 . In this way, flange  44  can engage with chamfer  31  to hold reservoir poppet  28  against the bias of spring  32 . Flange  44  preferably has sufficient strength to hold face seal portion  30  against the bias of spring  32 , but also is flexible enough to allow movement of face seal portion  30  through or past flange  44  in either direction (i.e., to the right or left with respect to  FIG. 5 ). Flange  44  may be annular and extend around the inner perimeter of passageway  24 , as shown, or may instead have a different shape or configuration that can provide the function of engaging and disengaging sufficiently with face seal portion  30  in the manner described above. Further, flange  44  may be formed integrally with passageway  24  or may be formed separately and attached to the interior of passageway  24 , such as with adhesives or the like. Spring  32  preferably has sufficient spring force to provide the desired amount of sealing between face seal portion  30  and valve seat  34  when face seal portion  30  is above flange  44  with respect to  FIG. 6  (see  FIG. 13 , for example). Spring  32  should not be so strong, however, that it pushes reservoir poppet  28  past flange  44  toward valve seat  34  when it is instead desired for face seal portion  30  to be on the opposite side of flange  44 . 
     Fluid passageway  24  also includes within its internal area a poppet valve seat  40  having sealing surface  41  adjacent to cylinder poppet  36 . Cylinder poppet  36  includes face seal portion  37  that is preferably a ring-like protrusion that extends around the outer perimeter of cylinder poppet  36 . Face seal portion  37  includes a sealing surface  39  for providing a seal with surface  41  of valve seat  40 . Surface  41  of valve seat  40  that comes into contact with surface  39  of face seal portion  37  is preferably a generally smooth surface that allows for a fluid tight seal between surface  39  of face seal portion  37  and surface  41  of valve seat  40 , when such sealing is desired. 
     In  FIG. 13 , pump assembly  10  is shown in a configuration where sealing surface  39  of poppet face seal portion  37  contacts sealing surface  41  of poppet valve seat  40  to provide a fluid tight seal. Poppet spring  38  engages cylinder poppet  36  and biases cylinder poppet  36  toward valve seat  40 . Poppet spring  38  is preferably strong enough to provide a fluid tight seal between sealing surface  39  of poppet face seal portion  37  and sealing surface  41  of valve seat  40 . Spring  38  is preferably not so strong that the cylinder poppet  36  is prevented from being moved back to its position shown in  FIGS. 5 and 6 . Such a movement of cylinder poppet  36  away from valve seat  40  allows fluid to pass from fluid passageway  24  into ports  20  and  21  during operation of pump assembly  10 . 
     The internal area or portion of fluid passageway  24  further includes a lip seal  42  that extends generally from the area between valve seat  40  and flange  44 . In one preferred embodiment, lip seal  42  may be generally conical in shape such that it tapers from a first cross-section in the pump body to a point or edge at its other end. This lip seal  42  is shown in cross-section in  FIG. 6  as a finger-like portion that extends into fluid passageway  24 . It is contemplated, however, that lip seal  42  has a different configuration or shape for sealing against the outside surface of reservoir poppet  28 . Lip seal  42  is preferably configured so that it can contact the outer surface of reservoir poppet  28  and provide a fluid tight seal between lip seal  42  and reservoir poppet  28  when reservoir poppet  28  is positioned with face seal portion  30  out of contact with valve seat  34 , and with chamfer  31  in contact with flange  44 . Lip seal  42  is preferably further configured to allow smooth movement of reservoir poppet  28  into and out of contact with lip seal  42 . However, lip seal  42  will be spaced from the outer surface of reservoir poppet  28  when the portion of reservoir poppet  28  that is adjacent to lip seal  42  is smaller in diameter than lip seal  42 . This will occur, for example, when reservoir poppet  28  is moved so that face seal portion  30  is in contact with valve seat  34 . In this mode, fluid would then be able to move through fluid passageway  24  and past lip seal  42 . 
     As illustrated in  FIG. 6 , cylinder poppet  36  includes receiver  48  that is designed to slidingly engage with nose portion  50  of reservoir poppet  28 . As shown, receiver  48  provides an opening or hole that can receive and engage with nose portion  50 . Such engagement between nose portion  50  and receiver  48  helps to maintain coaxial alignment of reservoir poppet  28  and cylinder poppet  36  in pump body  12  and throughout the range of travel of reservoir poppet  28  and cylinder poppet  36 . Nose portion  50  and reservoir poppet  28  can be designed in any manner that provides at least some overlapping sliding engagement between reservoir poppet  28  and cylinder poppet  36  for providing an aligning function between these components. When reservoir poppet  28  is moved away from valve seat  34  so that chamfer  31  is engaged with flange  44  against the bias of spring  32 , nose portion  50  of reservoir poppet  28  can slide within and push against an inside end surface of receiver  48  of cylinder poppet  36  against the bias of poppet spring  38 , thereby allowing for a certain fluid flow path. Thus, it is also preferable that poppet spring  38  and spring  32  are chosen to provide the desired ease of movement of components. That is, undue force should not be required to move the springs and poppets through the various operation modes of pump assembly  10 . In particular, it is required for operation of pump assembly  10  that the sides of pump body  12  are compressible to thereby manipulate the position of reservoir poppet  28  and cylinder poppet  36  relative to each other and pump body  12 . In order for this to be possible, it is preferable that reservoir poppet  28  is in sufficiently close proximity to the side of pump body  12  so that squeezing pump body  12  with a reasonable amount of force will move reservoir poppet  28  within pump body  12  into certain positions. 
     Pump body  12  further includes fluid bypass chamber  46  that is connected for fluid communication with fluid passageway  24  under certain operating conditions or modes of pump assembly  10 . Fluid bypass chamber  46  includes ball check valve  54  having ball  56  and spring  58 . Spring  58  biases ball  56  within chamber  46  along a check valve axis  27  toward ball valve seat  52 , which is a portion or edges of chamber  46  that form a diameter that is smaller than the diameter of ball  56 . In this way, a fluid tight seal may be formed between ball  56  and ball valve seat  52  when the system is in a state of equilibrium or when there is fluid pressure in chamber  64 . This seal prevents the undesired movement of fluid through bypass chamber  46  except under certain operating conditions of pump assembly  10 . As with the other springs used in pump assembly  10 , spring  58  should be sufficiently strong to keep ball  56  in its normal or closed position against ball valve seat  52  under certain operating circumstances. However, spring  58  should also allow for a predetermined flow of fluid against the bias of spring  58  to move the ball  56  out of contact with ball valve seat  52  to allow fluid to flow through bypass chamber  46 . As shown, fluid may move from fluid passageway  24  into bypass chamber  46  through a bypass input channel  62  during a deflation configuration of pump assembly  10 . 
     When there is a sufficient pressure in combination with sufficient volume of pressurized fluid in chamber  46  to move ball  56  against the bias of spring  58 , the fluid will be able to move freely from input channel  62  and through bypass chamber  46 . Fluid may then exit bypass chamber  46  through bypass output channel  64  that provides a second fluid connection between bypass chamber  46  and fluid passageway  24 . Bypass output channel  64  is positioned with respect to lip seal  42  so that certain operating conditions will provide a fluid path in which fluid passes by reservoir poppet  28  and enters transfer chamber  22 . The valve style used in fluid bypass chamber  46  of  FIG. 1  is shown as a ball check valve, but it could instead include any number of designs such as a “duck bill valve”, flap, or the like, which react to pressurized fluid in generally the same manner as the ball check valve  54 . 
     In order to provide a compact design, the check valve axis  27  as defined by bias direction of spring  58  is preferably provided at an angle greater than zero degrees (non-parallel) to the poppet valve axis  23  of reservoir poppet  28  and cylinder poppet  36 . If the check valve axis  27  and poppet valve axis  23  are generally parallel, bypass input chamber  62  and bypass output chamber  64  would be spaced further apart than in configurations where the check valve axis  27  is at an angle to the poppet valve axis  23  in order to accommodate the check valve  54 . This would have the effect of increasing width  25  of pump body  12 . In the arrangement where the check valve axis  27  and poppet valve axis  23  are generally perpendicular, bypass input chamber  62  and bypass output chamber  64  are closer together such that the width  25  of pump body  12  can be at least slightly smaller. 
     The components of pump assembly  10  can be positioned in a configuration that provides an auto-inflation resistance mode. In this mode, the cylinders are in a deflated condition and spontaneous inflation of the cylinders will preferably be difficult or impossible due to the positions of the poppets, springs and chambers of pump assembly  10 . No inflation of the cylinders can occur until pump bulb  14  is manipulated in a specified manner. In this mode, the fluid of the system will typically be contained within reservoir port  18 , transfer chamber  22 , and the reservoir (not shown), and this fluid cannot travel into ports  20  and  21  and the attached cylinders. In this mode, reservoir poppet  28  is being held against the bias of spring  32  by flange  44  within fluid passageway  24 . Nose portion  50  of reservoir poppet  28  is engaged with the receiver  48  of cylinder poppet  36  in a way that pushes cylinder poppet  36  against the bias of poppet spring  38 . Reservoir poppet  28  is thus positioned so that its outer surface is in contact with lip seal  42 , thereby creating a fluid-tight seal between reservoir poppet  28  and lip seal  42 . 
     In most cases, some portion of the fluid from the reservoir will move into port  18  and transfer chamber  22 , particularly when the reservoir is under pressure. Any such pressurized fluid in transfer chamber  22  can move into fluid passageway  24  and move reservoir poppet  28  slightly toward cylinder poppet  36 . This movement of reservoir poppet  28  allows fluid to flow from transfer chamber  22  through a gap between face seal portion  30  and reservoir poppet valve seat  34 . This fluid will then enter internal chamber  16  through connecting channel  26 . Movement of fluid into chamber  16  of pump bulb  14  will stop when the pressure has generally equalized between chamber  16  and the reservoir. The bias of spring  32  can then move face seal portion  30  back into contact with valve seat  34 , thereby limiting or preventing further fluid flow into chamber  16 . 
     Because lip seal  42  and reservoir poppet  28  form a fluid tight seal, as described above, no fluid can move past this seal toward ports  20  and  21  and connected cylinders. In addition, fluid attempting to move into fluid bypass chamber  46  through bypass output channel  64  will be prevented from moving past ball check valve  54  by the seal of ball  56  against ball valve seat  52 . Thus, no fluid will be able to pass into fluid passageway  24  or ports  20  and  21  by this path. In this state of equilibrium, fluid will thus be held within the reservoir, connecting reservoir port  18 , transfer chamber  22 , annular channel  68 , radial channels  70 ,  72 , and  74 , as well as chamber  16 . When the pump is configured in this mode, there may be small amounts of residual fluid contained in the various portions of the pump assembly, and the cylinders will be partially or completely deflated or collapsed. 
     The components of pump assembly  10  can be positioned in a manner that provides an activation mode of pump assembly  10  for cylinder inflation. This is the mode in which the user activates pump assembly  10  to begin the process of cylinder inflation. To activate pump assembly  10 , pump bulb  14  is squeezed or compressed by the user. This motion forces the fluid contained within pump chamber  16  through connecting channel  26  and into fluid passageway  24  under relatively high fluid pressure. This high pressure fluid forces chamfer  31  of face seal portion  30  of reservoir poppet  28  past flange  44 , which flange is made of a material that is relatively flexible to allow face seal portion  30  to move past it, yet sufficiently strong to hold reservoir poppet  28  against the bias of spring  32 . The bias of spring  32  will then push reservoir poppet  28  and face seal portion  30  against valve seat  34 , thereby providing a fluid tight seal between face seal  30  and valve seat  34 . Because the portion of reservoir poppet  28  adjacent lip seal  42  is now smaller in diameter than the internal opening provided by lip seal  42 , lip seal  42  is not in contact with reservoir poppet  28  in this mode (i.e., a gap is created between reservoir poppet  28  and lip seal  42 ). Thus, fluid can move past lip seal  42  and toward cylinder poppet  36 . In order for fluid to move past cylinder poppet  36  and into ports  20  and  21 , however, the fluid pressure must be high enough to overcome the bias of poppet spring  38 , which is now pushing cylinder poppet  36  in fluid tight contact with poppet valve seat  40 . The amount and pressure of the fluid may or may not be sufficient to cause such a movement of cylinder poppet  36  in this pump activation mode. 
     Where the fluid pressure is sufficiently high to overcome the bias of poppet spring  38 , fluid-tight contact between cylinder poppet  36  and poppet valve seat  40  can be broken, thereby providing a gap between sealing surface  39  of poppet face seal portion  37  and sealing surface  41  of valve seat  40 . This may be referred to as the pumping mode of pump assembly  10 . Fluid may then flow past lip seal  42  and cylinder poppet  36 , and then into ports  20  and  21  and the attached inflatable cylinders. In particular, after a first volume of pressurized fluid from pump bulb is moved past cylinder poppet  36  and into the cylinders (e.g., as described above), the bias of poppet spring  38  will push cylinder poppet  36  back into contact with poppet valve seat  40  to stop flow so that pump bulb  14  can be refilled. 
     In the pump bulb filling mode, pump bulb  14  is pulling or drawing fluid from the reservoir and through the various chambers of the system. Pump bulb  14  is preferably selected from a material that is relatively elastic and easy for a user to compress, but should also have sufficient structural integrity that it tends to move back toward its original size or configuration when not subjected to external pressure. That is, when the user releases pump bulb  14 , it should expand generally to its original shape and size, thereby providing a situation where pump bulb chamber  16  and fluid passageway  24  are placed under negative pressure. This negative pressure provided by the expansion of pump bulb  14  will draw fluid from the reservoir through reservoir port  18  and into chamber  16  of pump bulb  14 . The negative pressure within pump bulb  14  and connected chambers can move reservoir poppet  28  in a way that breaks the seal between face seal portion  30  and valve seat  34 . Fluid may then flow from the reservoir into annular channel  68 , radial channel  70 ,  72 , and  74 , and transfer chamber  22 , past face seal portion  30 , and into fluid passageway  24 . Any fluid under negative pressure within fluid passageway  24  will move into chamber  16  of pump bulb  14  until chamber  16  is full and/or there is no longer enough negative fluid pressure to keep face seal portion  30  from moving toward valve seat  34 . Spring  32  then causes reservoir poppet  28  to reseat itself against valve seat  34 . At this point, the user may then squeeze or compress pump bulb  14  to again move fluid from pump bulb  14  into ports  20  and  21  and inflatable cylinders, as described above. 
     Under certain conditions, when pump bulb  14  is pulling or drawing fluid from the reservoir and through the various chambers of the system, negative fluid pressure may cause reservoir poppet  28  to move in a way where a seal can be formed between face seal portion  30  and flange  44 . If such seal is formed, a situation might exist in which the negative pressure in pump bulb  14  prevents reservoir poppet  28  from moving toward valve seat  34 . This condition may prevent fluid from flowing from the reservoir to refill the pump bulb  14 . If this occurs, some corrective action may be required such as may include at least some deflation of the cylinders before the inflation process can continue. 
     In order to provide a free path for fluid flow if reservoir poppet  28  and flange  44  come into contact with each other during pump bulb refilling, pump assembly  10  preferably includes a low flow fluid path such as a vent or controlled leak or the like that permits some fluid flow from one side of flange  44  to the other side in the event that face seal portion  30  is drawn into contact with flange  44 . One configuration of such a fluid path is illustrated in  FIGS. 10 and 11 . In particular,  FIG. 10  shows a cross-sectional view of pump assembly  76 , which is preferably similar to pump assembly  10  of  FIG. 1 .  FIG. 11  shows a cross-sectional view of pump assembly  76  taken along the line  11 - 11  of  FIG. 10 . Pump assembly  76  includes suction poppet  78  having face seal portion  80 . Flange  82  is positioned within fluid passageway  84  and includes protrusions  86 ,  88 , and  90 . As shown, protrusions  86 ,  88 , and  90  extend outwardly from flange  82  and are spaced apart around the circumference of flange  82 . In this way, if surface  92  is drawn into contact with protrusions  86 ,  88 , and  90 , a gap is provided between flange  82  and face seal portion  80  that can allow for fluid flow through the gap. Such protrusions can be provided on flange  82 , face seal portion  80 , or both. This provides another fluid path between surface  92  and flange  82 . Any bumps, ridges, grooves, openings, channels, or the like that function to allow fluid flow when surface  92  contacts flange  82  can be used. For example, a small opening(s) such as a hole or orifice can be provided in one or both of flange  82  and face seal portion  80 . 
     The sequence of filling pump bulb  14  under negative pressure and forcing the fluid from pump bulb  14  under positive pressure may be repeated as many times as necessary to achieve the desired inflation of the cylinders and/or to empty the connected reservoir. Once inflated, the fluid within the cylinders and ports  20  and  21  is under relatively high pressure. While poppet spring  38  preferably has a sufficiently strong bias to keep cylinder poppet  36  pressed against poppet valve seat  40 , the relatively high pressure fluid in the cylinders and connected chambers also pushes sealing surface  39  of face seal portion  37  of cylinder poppet  36  into contact with sealing surface  41  of valve seat  40 , further strengthening this seal. This seal between cylinder poppet  36  and valve seat  40  is particularly important to keep the cylinders inflated (i.e., to prevent undesirable transfer of fluid from the cylinders into fluid passageway  24 ). Because the only path for fluid to move from ports  20  and  21  into fluid bypass chamber  46  is through fluid passageway  24 , it is likewise not possible for fluid from the cylinders to move into fluid bypass chamber  46  without first breaking the seal between cylinder poppet  36  and its poppet valve seat  40 . 
     When the user desires to deflate the cylinders, the walls of pump body  12  will be manually compressed in the general area of fluid passageway  24 . In order to assist the user in finding the proper area for compression, the outer surface of pump body  12  may be provided with raised or otherwise detectable areas for easier determination of proper manipulation locations on the pump body  12 . One example of such a detectable area is illustrated as a user pressure pad  66 , which is a raised surface portion on the side of pump body  12  that would be detectable by the human fingers. A compressive force on pump body  12  at pressure pad  66  forces reservoir poppet  28  away from valve seat  34  by a sufficient distance that face seal portion  30  moves toward cylinder poppet  36  past flange  44 . When the compressive force on pump body  12  is released, flange  44  then engages face seal portion  30  at chamfer  31  to hold reservoir poppet  28  in place against the bias of spring  32 . This compression of pump body  12  simultaneously moves nose portion  50  of reservoir poppet  28  into contact with receiver  48  of cylinder poppet  36 , which also breaks the seal between cylinder poppet  36  and poppet valve seat  40 . Further, such pump body compression also causes reservoir poppet  28  to be in a position where lip seal  42  is in contact with reservoir poppet  28 , which provides a fluid tight seal between these surfaces. Fluid from the cylinders and connecting ports  20  and  21  may then flow around cylinder poppet  36 , past poppet valve seat  40 , and into bypass input channel  62 . Notably, a single compressive squeeze by the user is sufficient to put pump assembly  10  in this cylinder deflation mode. In other words, there is no need for the user to continue to hold pump body  12  in this compressive condition while the cylinder deflation is occurring. 
     Once the fluid enters bypass input channel  62 , it moves directly into fluid bypass chamber  46 , where sufficient fluid pressure can unseat ball  56  from ball valve seat  52  and allow fluid to move out of chamber  46  through bypass output channel  64  and into fluid passageway  24 . The fluid can then move through annular channel  68 , radial channels  70 ,  72 , and  74 , and then into transfer chamber  22  to port  18 , and then into the reservoir. Fluid also flows into an open space  75  that extends into the general area of the pressure pad  66 . Annular channel  68  and radial channels  70 ,  72 , and  74  are preferably designed to allow fluid to flow from fluid passageway  24  to transfer chamber  22  when pressure pad  66  is being compressed to activate the deflation mode and space  75  is minimized or eliminated by compression of pad  66 . In this way, fluid flow will not be interrupted if compression of pressure pad  66  is maintained. 
     Because the fluid within the cylinders before deflation is under relatively high pressure, an initial volume of pressurized fluid will move under pressure from ports  20  and  21  and into pump body  12  upon compression of pump body  12 . After this initial volume has been transferred and the fluid has reached an equilibrium pressure, the cylinders may be manually compressed or manipulated to transfer the remainder of the fluid to the reservoir without the need to squeeze pad  66  or hold the pump, thereby completely deflating the cylinders. Pump assembly  10  is then configured again in its auto-inflation resistance mode, as described above. 
       FIG. 12  illustrates an embodiment of an implantable penile prosthesis system  120  of the invention, which includes a pump of the type illustrated in  FIGS. 1 through 11 , reservoir  122  that is separate from pump assembly  124 , and cylinders  126 . In general, this system  120  utilizes pump assembly  124  and reservoir  122  to inflate cylinders  126 , with connecting tubing attached between pump assembly  124  and both reservoir  122  and cylinders  126 . Pump assembly  124  can also be used to deflate the cylinders, as described above. Reservoir  122  is preferably constructed from a thick, high durometer elastomeric material, such as silicone and is specifically sized to hold a certain volume of fluid that corresponds to at least the volume difference desired to expand the cylinders  126 . 
     As shown, two tubes  128  extend from pump assembly  124 , each of which connects to one of cylinders  126 . A single tube  130  extends from reservoir  122  for connection to pump  124 . It is contemplated, however, that the number of tubes and the branching of tubes can differ from this arrangement, depending on the design of the pump and other components. As described above relative to pump assembly  10 , the body of pump assembly  124  can be squeezed generally along its longitudinal axis in order to deflate cylinders  126 , which thereby opens certain valves within the pump and allows pressurized fluid from the cylinders to move through the pump and enter the reservoir. Inflation of the cylinders can be accomplished by first squeezing the pump bulb to activate pump assembly  124 , then squeezing the pump bulb repeatedly until the desired cylinder inflation is achieved. 
     The present invention has now been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is hereby incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein, but only by the structures described by the language of the claims and the equivalents of those structures.