Abstract:
A lockout valve for an inflatable penile prosthesis which responds to internal fluid pressure. The lockout valve comprises a housing having inlet and outlet ports, an interior chamber, an apertured valve seat, and a poppet biased toward the closed position. The inlet communicates with the prosthesis reservoir, and the outlet communicates with the interior chamber and the prosthesis pump. The housing includes a flexible diaphragm which moves toward the poppet when flexed inwardly. Fluid pressure through the inlet port urges the poppet into sealing engagement against the valve seat, therefore closing the lockout valve. Negative fluid pressure applied to the interior chamber from the outlet port (when the pump is actuated) causes the diaphragm to flex inwardly and contact the poppet to open the valve. The lockout valve operates like a check valve when subject to reverse flow.

Description:
This application is a continuation (and claims the benefit of priority under 35 U.S.C. 120) of U.S. application Ser. No. 08/681,859, filed Jul. 29, 1996 now U.S. Pat. No. 5,851,176. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relate, generally to lockout valves for implantable penile prostheses, and particularly to a valve assembly which responds to an internal pressure differential within the prosthesis and which may be retrofitted to an existing implanted prosthesis. 
     2. Content of the Prior Art 
     Implantable penile prostheses for treating impotence are well know to the art. These prostheses generally include a reservoir of biocompatible liquid such as physiological saline implanted within the patient s abdomen, a pump and valve block located within the patient&#39;s scrotum, and a pair of cylinders which are implanted within the corpus cavernosae of the penis. Actuating the pump transfers fluid from the reservoir to the cylinders causing them to inflate, thus producing an erection. When the patient wishes to return to a tumescent or flaccid state, he releases the fluid from the cylinders back into the reservoir, in some cases by manually compressing the cylinders to force fluid back to the reservoir. Some representative examples of these penile prostheses and their components or variations are shown in several United States patents to Buuck &#39;102, Cowen &#39;611, &#39;417, &#39;485, and &#39;914, Fogarty &#39;446, 183, and &#39;826, Bley &#39;020, Uson &#39;711, and Strauch &#39;122, which are incorporated herein by reference. 
     A wide variety of embodiments of such penile prostheses are known, including the representative examples mentioned above. For example, some prostheses do not utilize a pump, but rather rely on physical compression of the reservoir or a pressurized reservoir to inflate the cylinders. While some prostheses locate the reservoir or pump subcutaneously within the patient&#39;s abdomen, others provide a unitary pump and reservoir located within the patient&#39;s scrotum. For purposes of this disclosure, many of these prostheses may be considered substantially interchangeable to the extent they include a reservoir, pump, and cylinders (or their structural or functional equivalents). 
     As noted, one of the components of many prostheses is a valve block, which contains one or more check valves regulating the flow of fluid between the reservoir and cylinders. These check valves prevent the flow of fluid in one direction, and may be spring-biased to remain in a closed position preventing flow in the forward direction until sufficient internal pressure is exerted on the valves to cause them to open. In some embodiments, the check valves are actually palpitatable valves which must be physically manipulated (such as by actuating the pump or squeezing the valve element) in order to open the valve to forward flow. 
     Another component is a release or relief valve, which serves to permit reverse flow from the cylinders to the reservoir when the release valve is selectively actuated by the patient. The release valve is usually located in the pump or valve block, between the pump and the cylinders, or within or near the cylinders. 
     While the check valves and release valves are suitable to selectively control the flow of fluid between the reservoir and the cylinders during normal operation, it was soon recognized that pressure exerted on the reservoir during physical activity or movement by the patient could cause the inadvertent and undesired inflation of the cylinders. If sufficient pressure is placed on the reservoir (for example, when a patient who has an abdominal reservoir bends over, or a patient having a scrotal reservoir sits down or crosses his legs), the pressure on the reservoir may overcome the resistance of the spring-biased check valve, causing complete or partial inflation of the cylinders. In prostheses having pressurized reservoirs, the unintended activation of the control valve can produce the same result. In the event of accidental auto-inflation—either partial or total—the patient would be required to manually open the release valve and physically compress the cylinders to deflate them. 
     In addition, encapsulation or calcification frequently occurs around the reservoir. This can lead to more frequent instances of auto-inflation (since the capsule may transmit or focus more pressure on the reservoir when the patient moves or bends), or result in continuous partial inflation because the capsule exerts pressure on the reservoir that overcomes the check valve or prevents complete deflation of the cylinders. 
     As may be readily appreciated, instances of accidental auto-inflation can be quite embarrassing and painful for a patient, and may restrict their ability to engage in certain recreational or daily activities. In addition, even for patients whose actual incidents of accidental auto-inflation might be infrequent, the mere risk of such an occurrence may cause them to refrain from activities in which they might otherwise engage. 
     Lockout valves to prevent auto-inflation of the chambers are therefore well known to the art. As meant herein, the term “lockout valve” means a valve or flow control other than the check or release valves, which serves to prevent accidental auto-inflation and is characterized by requiring selective actuation or activation by the patient in order to permit fluid flow in the positive direction (i.e., from the reservoir to the cylinders), and which will remain closed despite high fluid pressures experienced by or exerted from fluid in the reservoir or connecting tubing. 
     Conventional lockout valves include those which are normally-closed (returning to a completely closed position when not being manually actuated) versus bi-stable (having distinct open and closed positions in which the valve will remain until manually moved to the contrary position). 
     Representative examples of various lockout valves are shown in several United States and foreign patents, the disclosures of which are incorporated herein by reference. 
     The Cozzi &#39;798 patent application discloses a prostheses having an abdominal reservoir with either a palpitatable or bi-stable “spigot” type lockout valve located in the scrotum. The Cozzi &#39;798 patent does not utilize a pump, but instead relies on manual compression of the reservoir. The Trick &#39;110 patent shows a bi-stable lever-type valve mounted on a pressurized reservoir located within the scrotum. The Stucks &#39;416 patent provides bi-stable valves associated with each cylinder which control both inflation and deflation. 
     The Evans &#39;491 and 968 patents disclose bi-stable crossover valves which are connected in line between the pump and cylinders. The Burton &#39;509 patent discloses an embodiment having a bi-stable valve located in the valve block, and an embodiment in which the valve actuator is located inside the pump bulb. 
     The Daly &#39;403 and Trick &#39;360 patents disclose palpitatable valves which are formed integrally with the pump and are therefore located within the patient&#39;s scrotum. The Lash &#39;693 patent shows a palpitatable valve disposed slightly downstream from the unitary pump and reservoir. 
     The Fischell &#39;242 and &#39;830 patents disclose subcutaneous lockout valves positioned within the patient&#39;s abdomen or pubic area, which are opened by depressing a spring-biased plunger or resilient diaphragm. 
     Although not exhaustive of the various structures and embodiments of lockout valves developed or utilized with inflatable penile prostheses, these examples are believed to represent the basic concepts or methods previously employed by those skilled in the art of designing penile prostheses to prevent accidental auto-inflation. 
     However, these designs do present or reflect several significant disadvantages or drawbacks. 
     Several of the lockout valves require two-handed operation—one to actuate the lockout valve, and the other to operate the pump or compress the reservoir. It may also be difficult to initially locate or manipulate the activation mechanisms in some of the lockout valves. 
     Subcutaneous abdominal lockout valves may become less responsive when implanted due to calcification and the formation of scar tissue, or due to movement within the patient unless the lockout valve is secured to an available anatomical structure. 
     Some of the lockout valves can cause additional discomfort due to their size or shape, or may expose the patient to the risk of internal injuries or damage due to interference with vesicles or lumen within the scrotum, or as a result of manipulating the valve&#39;s actuation mechanism. The size and shape of some lockout valves may increase the complexity or risks associated with the implant procedure itself, or prohibit some types of less invasive surgical procedures. 
     Finally, some of the valves are unduly complicated or expensive to manufacture, and may be subject to mechanical wear, failure, or rejection that would necessitate repair or replacement, thereby involving additional surgery for the patient. 
     SUMMARY OF THE INVENTION 
     The lockout valve of this invention is designed to prevent accidental auto-inflation when fluid pressure from the reservoir exceeds the threshold opening value of the check valves, and yet still provides automatic operation whenever the patient selectively actuates the pump bulb without the need to separately operate the lockout valve. 
     The lockout valve of this invention provides several additional advantages compared with contemporary designs. It is very small and inexpensive to manufacture. Its components can be fabricated from biocompatible silicone rubber or plastics, and the design does not require high fabrication tolerances. It has relatively few moving parts, and is not as prone to damage or failure due to fatigue or wear. It may be manufactured as an integral component of a penile prosthesis, or retrofitted to a. wide variety of existing prostheses (in which the reservoir is spaced apart from the cylinders) using existing tubing and conventional connectors. The lockout valve allows setting a lower threshold pressure for opening the main check valve of the prosthesis, which in turn permits the pump bulb to be activated with less “squeezing” force. The ability to modify the pump bulb and valve block to operate under less external pressure may also allow a release valve which is easier to operate. Since the lockout valve itself does not require manipulation by the patient, it may be located anywhere between the reservoir and pump—such as on the reservoir or in the abdomen—and therefore outside the scrotum. At internal pressures below the threshold value for the prosthesis&#39; check valve, the lockout valve may optionally exhibit a “leaky” characteristic which facilitates maintaining a normal pressure equilibrium between the reservoir and pump as comparably small compressive forces are placed on each, which may not be accomplished using a normally closed or bi-stable lockout valve. 
     Briefly described, the pressure-responsive lockout valve of this invention consists of a valve body or housing having inlet and outlet ports, with an interior chamber, an apertured valve seat, and a poppet which moves axially relative to that valve seat and aperture. The inlet leads from the reservoir to the side of the valve seat opposing the interior chamber, and the outlet fluidly communicates with the interior chamber and the cylinders. The poppet is normally biased toward or in the closed position by a spring force exerted by a plurality of flexible tines. A portion of the valve body proximate to the interior chamber defines a flexible membrane or diaphragm having an area generally larger than the area of the aperture in the valve seat or the face of the poppet. That diaphragm generally moves toward the poppet and valve seat when flexed inwardly. 
     In operation, fluid pressure exerted from the reservoir through the inlet port urges the poppet into more positive sealing engagement against the valve seat, therefore closing the lockout valve and preventing fluid in the reservoir from inflating the cylinders. Negative fluid pressure applied to the interior chamber from the outlet port and tubing when the pump is selectively actuated by the patient causes the diaphragm to flex inwardly and contact the poppet. The force exerted on the poppet by the diaphragm will exceed the fluid pressure exerted from the reservoir and the lockout valve will automatically open, thereby permitting fluid in the reservoir to inflate the cylinders. The lockout valve operates like a check valve when subject to reverse flow, so that when the patient opens the release valve on the pump and deflates the cylinders, the positive pressure of the fluid flowing in the reverse direction through the outlet port and into the interior chamber exerts pressure on the poppet which exceeds the spring force exerted by the flexible tines, and the lockout valve opens. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of an inflatable penile prosthesis including one embodiment of the pressure-responsive lockout valve of this invention implanted within a male patient; 
     FIG. 2 is a perspective view of the exterior of the pressure-responsive lockout valve of FIG. 1; 
     FIG. 3 is a side cross section view of the pressure-responsive lockout valve of FIG. 1 taken through line  3 — 3  in FIG. 2; 
     FIG. 4 is a transverse cross section view of the pressure-responsive lockout valve of FIG. 1 taken through line  4 — 4  of FIG. 3; 
     FIG. 5 is a diagrammatic illustration of the pressure-responsive lockout valve of FIG. 1 in the closed position; 
     FIG. 6 is a diagrammatic illustration of the pressure-responsive lockout valve of FIG. 1 in the open position due to negative pressure applied on the outlet port; and 
     FIG. 7 is a diagrammatic illustration of the pressure-responsive lockout valve of FIG. 1 in the open position due to reverse flow from the outlet port. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The fluid pressure-responsive lockout valve for an inflatable penile prosthesis and its method of operation are shown in FIGS.  1 - 7 , and generally referenced therein by the numeral  10 . For expedience, the fluid pressure-responsive lockout valve  10  may be referred to herein simply as the lockout valve  10 . 
     Referring particularly to FIG. 1, the lockout valve  10  is shown in its anatomical environment within a male patient  12  as a component of an inflatable penile prosthesis  14 . The prosthesis  14  includes a remote reservoir  16  located in the abdomen of the patient  12 , a pump bulb  18  and unitary valve block  20  located within the scrotum of the patient  12 , and a pair of inflatable cylinders  22  each located within the corpus cavernosa of the penis of the patient  12 , these components being operatively connected in fluid communication by a plurality of segments of tubing  24 . The lockout valve  10  is disposed roughly equidistant between the reservoir  16  and valve block  20 . The prosthesis  12  shown herein for exemplary purposes is of the type whose manufacture and use is generally described in greater detail by the Cowen &#39;611, &#39;417, &#39;485, and &#39;914, Fogarty &#39;446, 183, and &#39;826, and Bley &#39;020 patents identified above and incorporated herein by reference as though fully set forth. It is understood that the lockout valve  10  may be utilized with a wide variety of prostheses  12  other than this representative example. 
     Referring particularly to FIGS.  2 - 4 , the structure of one embodiment of the lockout valve  10  is shown in greater detail. The lockout valve  10  includes a housing or body  26  having a generally disk-shaped outer configuration with a plurality of steps or segments, with the body  26  being fluidly connected in line along the tubing  24  such that segments of the tubing extend outwardly in diametrically opposing directions from an inlet port  28  and an outlet port  30  extending through the outer walls of the body  26 . The body  26  defines a generally planar valve seat  32  having a central aperture  34 . The valve seat  32  and body  26  define an interior chamber  36  which is generally disposed on the opposite side of the valve seat  32  relative to the inlet port  28 , but in direct proximity to and fluid communication with the outlet port  30 . 
     A dumbbell-shaped poppet  38  or valve member is disposed or mounted within the aperture  34  of the valve seat  32  so as to move axially therein back and forth relative to the valve seat  32  and interior chamber  36 . The poppet  38  includes an enlarged disk-shaped head  40  and tail  42  which are connected by a generally cylindrical shaft  44 . The head  40  and tail  42  have diameters sufficiently large to cover and close the entire aperture  34 . The shaft  44  has a diameter sufficiently small so that inflation fluid may pass between the shaft  44  and valve seat  32  through the aperture  34 , and a length, sufficiently great so that the head  40  and tail  42  of the poppet  38  are spaced apart sufficiently that they can simultaneously be displaced from contact with the valve seat  32  on both sides thereof to permit fluid flow through the aperture  34 . Concurrently, the valve seat  32  has a sufficient thickness and the shaft  44  a sufficient diameter to prevent the poppet  38  from pivoting out of proper alignment, thereby constraining the axial movement of the poppet  38  to generally parallel alignment with the longitudinal axis of the shaft  44  so the tail  42  of the poppet  38  contacts flush with the confronting planar surface of the valve seat  32 . 
     A plurality of flexible tines  46  spaced around the aperture  34  extend radially inward into the interior chamber  36  from the valve seat  32  in a spoke-like configuration, each of the tines  46  being angled generally acutely away from the valve seat  32 . Each tine  46  terminates in a beveled or truncated distal tip  48  disposed axially between the head  40  of the poppet  38  and the valve seat  32 , which together define a plane and support the head  40  of the poppet  38  to bias it away from the valve seat  32  into the interior chamber  36 . The distal tips  48  of the tines  46  are spaced sufficiently from the shaft  44  so that any two tines  46  on opposing sides of the shaft  44  will not both contact the shaft  44  and prevent further axial movement of the poppet  32  prior to the head  40  of the poppet  38  being moved axially as close to the valve seat  32  (or the tail  42  being moved axially as far away from the valve seat  32 ) as is desired or required for normal operation of the lockout valve  10 . 
     The body  26  of the lockout valve  10  also defines a generally circular flexible diaphragm  50  or membrane which traverses across the radial extent of the interior chamber  36 , the counter point of which is generally aligned with the longitudinal axis of the poppet  38  and the aperture  34 . The center point of the diaphragm  50  therefore moves toward the head  40  of the poppet  38  along the longitudinal axis when the diaphragm  50  flexes concavely inward into the interior chamber  46 , and the diaphragm  50  may also bow convexly outward away from the poppet  38 . The relative flexibility or resiliency of the diaphragm  50 , its diameter, and its spacing from the poppet  38  and valve seat  32  are such that at its maximum concave inward flexure, the diaphragm  50  contacts the head  40  of the poppet  38  and presses it fully toward the valve seat  32  to the extent permitted by the resiliency of the tines  46  or the physical interjection of the tines  46  between the head  40  of the poppet  38  and the confronting surface of the valve seat  32 . The diaphragm  50  may be molded integrally with the body  26 , or may be adhered or otherwise attached to the body  26  in applications where the body  26  must initially be left partially open to permit installation of the poppet  38  into the aperture  34  in the valve seat  32 . Similarly, the segments of tubing  24  may be molded integrally with the body  26 , or may be adhered or attached to the body  26  in fluid communication with the inlet port  28  and outlet port  30 . 
     The poppet  38  is lathed or otherwise fabricated from a more rigid polymer such as polysulfone that is sufficiently rigid to deform or stretch the aperture  34  to permit the head  40  or tail  42  of the poppet  38  to be forcibly pressed through the aperture  34  to mount the poppet  38  relative to the valve seat  32 , with the respective head  40  or tail  42  optionally being beveled or tapered to facilitate mounting while preventing inadvertent detachment. The body  26  of the lockout valve  10  may be fabricated from a biocompatible elastomer such as silicone rubber, a plastic or ploymer, or the like, using any conventional molding or fabrication procedure or assembly of separate subcomponents. The particular embodiment of the lockout valve  10  shown in FIGS.  2 - 4  may be constructed so that the body  26  has to have an overall diameter of approximately 1.0″ or less, with a total thickness on the order of 0.5″ or less. 
     It may readily be appreciated that lockout valve  10  of this invention may be fabricated in a variety of embodiments and configurations which are structurally and functionally interchangeable, the preferred embodiment of which has been disclosed in detail herein. In addition, the dimensions, tolerances, and physical characteristics of the materials selected for the lockout valve  10  may be determined based upon the particular application and conditions to which the lockout valve  10  will be subjected, and according to well known principles familiar to those of ordinary skill in designing such components. 
     The operation of the lockout valve  10  may be further understood with reference particularly to FIGS.  5 - 7 . The lockout valve  10  is connected in line with the reservoir  16  and pump valve block  20  by tubing  24  such that the inlet port  28  is functionally oriented towards and fluidly communicates with the reservoir  16 , and the outlet port  30  is functionally oriented towards and fluidly communicates with the valve block  20  or pump bulb  18 . In contrast, the spatial orientation of the lockout valve  10 , the inlet port  28 , and outlet port  30  may be configured or arranged in any manner that is deemed suitable or practical to fabricating the lockout valve  10 . 
     In this configuration, a liquid such as physiological saline or other inflation fluid contained within the reservoir  16  will flow along a path from the reservoir  16  through tubing  24  to the inlet port  28 , and through the inlet port  28  into the lockout valve  10  on the side of the valve seat  32  opposing the interior chamber  36 . When the aperture  34  is not closed by the tail  42  of the poppet  38 , the fluid will continue flowing along a path through the aperture  34  and into the interior chamber  36 . When the pump bulb  18  is actuated, a negative pressure (or suction) is exerted on the segment of tubing  24  extending from the valve block  20  or pump bulb  18  to the outlet port  30 , that negative pressure acting to draw fluid from the interior chamber  36  through the outlet port  30  and tubing  24  toward the pump bulb  18 . 
     Referring particularly to FIG. 5, if pressure is physically exerted on the reservoir to increase the internal fluid pressure within the reservoir and the tubing  24  connected to the inlet port  28 , that internal fluid pressure will cause the tail  42  of the poppet  38  to seat against and form a fluid-tight seal with the confronting face of the valve seat  32 . However, it has been found that the biasing force exerted by the tines  46  need not be so strong as to continuously maintain a fluid-tight seal between the poppet  38  and valve seat  32  in the absence of an internal fluid pressure from the reservoir  16  that exceeds the predetermined threshold pressure required to open the check valve in the valve block  20  leading to the cylinders  22 . Consequently, at an internal fluid pressure from the reservoir  16  less than the threshold opening pressure for the check valve, the lockout valve  10  may be “leaky” to the extent it is not normally closed or forms a fluid-tight seal. However, once the internal fluid pressure from the reservoir  16  approaches or exceeds the threshold pressure of the check valve, the lockout valve  10  becomes fluid-tight and increasing the internal fluid pressure from the reservoir  16  increases the integrity of that seal. 
     When the pump bulb  18  is selectively actuated by the patient  12 , the pump bulb  18  creates a negative internal fluid pressure within the tubing  24  and interior chamber  36 . This negative internal fluid pressure or vacuum force causes the diaphragm  50  to flex concavely inward into the interior chamber  36 , to a point at which the diaphragm  50  contacts the head  40  of the poppet  38  and moves the poppet  38  axially to displace the tail  42  from the valve seat  32  as shown particularly in FIG. 6, thereby opening the lockout valve  10  and permitting inflation fluid to flow from the reservoir  16  along a path through the tubing  24 , inlet port  28 , aperture  34 , interior chamber  36 , outlet port  30 , and tubing  24  to the valve block  20  and pump bulb  18 . 
     It may further be appreciated that a proper functional balance must be established between the internal fluid pressure exerted by the reservoir  16 , the biasing force of the tines  46 , and the negative internal fluid pressure resulting in the interior chamber  36  created by the pump bulb  18 . The pressure differential within the system would normally require a fluid pressure from the reservoir  16  that is less than the negative pressure exerted by the pump bulb  18  in order for the lockout valve  10  to open during use. However, the relatively large size of the diaphragm  50  compared to the relatively small diameters of the aperture  34  and the contact area between the tail  42  of the poppet  38  and the valve seat  32  provides a sufficient mechanical advantage which ensures that a moderate negative internal pressure exerted by the pump bulb  18  will overcome a significantly greater internal pressure created by compressing the reservoir  16 , but only when the pump bulb  18  has been selectively actuated by the patient  12 . Absent actuation of the pump bulb  18  or a negative internal pressure created by the pump bulb  18 , the poppet  38  is biased to its closed position (both by any internal pressure from the reservoir  16  and the spring force of the tines  46 ), and a fluid-tight seal is formed with the valve seat  32 . As such, the relevant criteria are the proportionate forces exerted on the poppet  38  due to the hydrodynamic forces on the diaphragm  50  and poppet  38 , the resulting mechanical force exerted by the diaphragm  50  on the poppet  38 , and the comparably small mechanical spring force exerted by the tines  46 . 
     The lockout valve  10  will remain in the sealed closed position until the internal pressure from the reservoir  16  drops sufficiently below a predetermined value which is characteristic to the lockout valve  10 , and which is below the threshold pressure required by the check valve, at which point the lockout valve  10  may be permitted to exhibit the “leaky” characteristic. The “leaky” characteristic of the lockout valve  10  is not believed to be necessary to the proper functioning of the lockout valve  10 , but in situations where the pump bulb  18  may be inadvertently compressed a small amount, the check valve will prevent auto-inflation of the cylinders  22  while the slight increase in internal pressure will be absorbed by the reservoir  16  and may then be retransmitted back to the pump bulb  18  through the lockout valve  10  when the compression is released, thus maintaining a normal equilibrium between the reservoir  16  and pump bulb  18  without a risk of inadvertent auto-inflation of the cylinders  22 . A normally closed or bi-stable lockout valve  10  that maintains a fluid-tight seal would not permit this operation. 
     As noted, the lockout valve  10  operates in a manner similar to a check valve when subject to reverse flow, as shown in FIG.  7 . When the patient activates the release valve (not shown) in the valve block  20  to permit deflation of the cylinders  22 , the increased internal pressure created by manually compressing the cylinders  22  causes increased internal pressure within the interior chamber  36 . The diaphragm  50  will bow convexly away from the poppet  38 , and the internal fluid pressure within the interior chamber  36  will exerting force on the tail  42  of the poppet  38  which overcomes the biasing force of the tines  46 , thus opening the lockout valve  10  and permitting the inflation fluid to flow in the reverse direction through the lockout valve and thus refilling the reservoir  16 . 
     Referring again to FIG. 1, it may be seen that in addition to fabricating the lockout valve  10  as a standard component of an assembled prosthesis  14  prior to initial implantation within a patient  12 , the lockout valve  10  may also be designed to permit retrofitting to an existing implanted prosthesis  14 . 
     In order to retrofit the lockout valve  10  to an existing prosthesis  14 , the lockout valve  10  is fabricated with a short segment of tubing  24  extending from each of the inlet port  28  and outlet port  30 , with each segment having a free end. An intermediate section of the tubing  24  between the reservoir  16  and valve block  20  or pump bulb  18  is cut or removed to produce two free exposed ends, and the lockout valve  10  is then spliced into that tubing  24  using a pair of mating connectors  52  of any conventional and suitable type available. The lockout valve  10  may be fabricated with the free ends of the segments of tubing  24  having one half of each pair of mating connectors  52  already attached, or the operator may attach the mating connectors  52  to all four free ends of the tubing during the retrofit procedure. It may be appreciated that in the case of retrofitted lockout valves  10 , the segments of tubing  24  or the lockout valve  10  should be color coded or marked with a visible or tactile indicia such as arrows that ensure the operator will properly orient and connect the lockout valve  10  with that the inlet port  28  disposed functionally towards the reservoir  16  and the outlet port  30  disposed functionally towards the valve block  20  and pump bulb  18 . 
     While the lockout valve  10  of this invention was conceived and designed for the purpose of providing an optimal solution to the problem of accidental auto-inflation of an inflatable penile prosthesis  13  as described above, it may be readily appreciated that this lockout valve  10  could be utilized successfully in other applications relating to other medical devices or products unrelated to the treatment of medical dysfunction. 
     One representative example in the field of medical devices would be an intravenous (IV) line used for the introduction of fluid medication to a patient. In a standard non-gravity IV line, a pump draws fluid from a reservoir such as an IV bag under vacuum, and pumps the fluid through a catheter or IV tube under pressure into the patient at a carefully metered rate. In some systems, if the IV line is detached from the pump or the pump is stopped—and the IV line is not manually closed by a valve—the IV fluid or medication may continue draining or being drawn into the patient at an unmetered rate, resulting in overmedication. Placement of a lockout valve  10  of the type disclosed herein between the IV pump and the IV bag will automatically terminate the flow from the IV bag in the event the negative pressure from the pump is interrupted. 
     A related example would be an arterial catheter used for injecting or withdrawing fluids from a patient. The lockout valve placed along the catheter between the injection site and the patient would prevent blood flowing through the catheter from the patient except when a syringe or hemotube is attached to the catheter and providing a source of negative pressure to withdraw a sample. The lockout valve would act as a check valve when administering medication or injecting fluids through the catheter. 
     It is also appreciated that various embodiments of the lockout valve  10  may be developed which utilize the inventive concept disclosed herein of a lockout valve  10  for a penile prosthesis  14  which responds to internal fluid pressures (static or dynamic) within the prosthesis  14  but which operate in different manners or modes. For example, in a system having a check valve in the valve block  20 , a subjectively less desirable but workable embodiment of the lockout valve  10  could be fabricated having a distinct section of tubing  24  extending from the valve block  20  or pump bulb  20  to carry inflation fluid under positive pressure back to the lockout valve  10  when the pump bulb  18  is actuated, with that positive pressure from the inflation fluid in the segment of tubing  24  acting on the valve member or poppet  38  (with the benefit of any necessary mechanical advantage or leverage) to open the lockout valve  10 . Alternately, a lockout valve  10  could be fabricated which responds to momentary fluid back-pressure created when the pump bullb  18  is actuated, however such a system would impose significant complexity in balancing the respective activation pressures for the lockout valve  10  and check valve. 
     While representative examples of the preferred embodiments of the above fluid pressure-responsive lockout valve  10  have been described in detail with reference to the attached drawing Figures, it is understood that various changes, adaptations, and modifications may be made in the fluid pressure-responsive lockout valve  10  and its method of fabrication and use without departing from the spirit and scope of the following appended claims.