Abstract:
A method for using a medical device in connection with a catheter for regulation or transfer of fluids to and from a patient. The method may include obtaining and using a medical device including a diaphragm having two unidirectional slit valves disposed therein that actuate in different directions, one slit valve actuating in one direction in response to infusion-induced pressure and another slit valve actuating in another direction in response to aspiration-induced pressure. The method may include infusing fluid through one of the unidirectional slit valves, through a lumen, and into a patient&#39;s body. The method may also include aspirating fluid from a patient&#39;s body through the lumen and another unidirectional slit valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/566,620, filed Dec. 4, 2006, now U.S. Pat. No. 9,044,541, which claims the benefit of U.S. Provisional Application No. 60/741,578, entitled “Pressure-Activated Proximal Valves,” filed Dec. 2, 2005, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    In medicine, an embolism occurs when an object (the embolus, plural emboli) migrates from one part of the body (through circulation) and causes a blockage of a blood vessel in another part of the body. Blood clots form a common embolic material. Other possible embolic materials include fat globules (a fat embolism), air bubbles (an air embolism), septic emboli (containing pus and bacteria), or amniotic fluid. Emboli often have more serious consequences when they occur in the so-called “end-circulation” areas of the body that have no redundant blood supply, such as the brain, heart, and lungs. Assuming normal circulation, a thrombus or other embolus formed in a systemic vein will always impact in the lungs, after passing through the right side of the heart. This forms a pulmonary embolism that can be a complication of deep vein thrombosis. 
         [0003]    Embolism can be contrasted with a “thrombus” which is the formation of a clot within a blood vessel, rather than being carried from elsewhere. Thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system (i.e., clotting factors). A thrombus is physiologic in cases of injury, but pathologic in case of thrombosis. A thrombus in a large blood vessel will decrease blood flow through that vessel. In a small blood vessel, blood flow may be completely cut-off resulting in the death of tissue supplied by that vessel. If a thrombus dislodges and becomes free-floating, it becomes an embolus. 
         [0004]    Some of the conditions in which blood clots develop include atrial fibrillation (a form of cardiac arrhythmia), heart valve replacement, a recent heart attack, extended periods of inactivity (see deep venous thrombosis), and genetic or disease-related deficiencies in the blood&#39;s clotting abilities. 
         [0005]    Preventing blood clots reduces the risk of stroke, heart attack and pulmonary embolism. Heparin and warfarin are often used to inhibit the formation and growth of existing blood clots, thereby allowing the body to shrink and dissolve the blood clots through normal methods (see anticoagulant). Regulating fluid flow through catheters can help minimize embolism and health risks associated therewith. 
       BRIEF SUMMARY 
       [0006]    One aspect of the present invention discloses a medical device comprising a diaphragm having at least one slit valve disposed therein and at least one valve control member. The term “diaphragm,” as used herein, can be defined as any membranous part that divides or separates. The valve control member can be configured to cover at least a portion of the diaphragm without covering any portion of the slit valve and can be further configured to control deflection of the diaphragm. In another aspect of the invention, the valve control member comprises at least one arm extending from an outer portion of the valve control member to an inner portion of the valve control member. In still another aspect of the invention, the valve control member comprises a plurality of arms extending from an outer portion of the valve control member to a center portion of the valve control member. Further, the medical device can comprise a valve housing having the diaphragm therein, the valve housing being configured to be attached to an elongated tubular member, the elongated tubular member configured for at least partial placement into a portion of a patient. In another aspect of the invention, at least a portion of the slit valve has a nonlinear orientation. In another aspect of the invention the slit valve further comprises a plurality of interconnected linear slits oriented in different directions. 
         [0007]    In another embodiment, a medical device for regulating fluid flow comprises a diaphragm having a slit valve disposed therein and a valve housing configured to secure the diaphragm at a peripheral portion of the diaphragm. A distal end of the valve housing can be further configured to attach to a proximal end of an elongated tubular member, such as a catheter. A central portion of the diaphragm is positioned relative to the peripheral portion of the diaphragm such that compressive forces acting on the peripheral portion of the diaphragm create moment forces which bias the slit valve in a neutral position. In one aspect of the invention, an outer portion of the diaphragm is thicker than an inner portion of the diaphragm. Alternatively, in another aspect of the invention, an outer portion of the diaphragm is thinner than an inner portion of the diaphragm. In still another aspect of the invention, the diaphragm may be substantially circular or substantially oval. In an additional embodiment of the invention, at least a portion of the diaphragm approximates the shape of a dome structure. In one aspect, the diaphragm further comprises a concave or convex annular member which circumscribes the dome structure. In one embodiment, the diaphragm is oriented substantially perpendicular to a direction of flow through the valve housing. In another embodiment, the diaphragm is oriented at an obtuse angle relative to a direction of flow through the valve housing. In one aspect, the diaphragm narrows from a lateral portion of the diaphragm to an opposite lateral portion of the diaphragm. In still another aspect, at least two slit valves are installed on opposing sides of the diaphragm. 
         [0008]    In another embodiment, the diaphragm of the medical device further comprises at least one protruding member on a proximal end of the diaphragm configured to assist the slit valve to return to the biased neutral position. In one aspect, the diaphragm further comprises a pair of centrally located opposing protruding members on a proximal end of the diaphragm configured to assist the slit valve to return to the biased neutral position. 
         [0009]    One embodiment of the invention contemplates a medical device comprising a diaphragm with at least one slit valve disposed therein. The proximal surface and distal surface of the diaphragm approximate a dome structure. The diaphragm is configured such that a portion of the proximal end of the diaphragm contiguous with the slit valve is thinner than an adjacent portion of the diaphragm. In one aspect, the diaphragm is secured at a peripheral portion by a valve housing, a distal end of the valve housing being configured to attach to a proximal portion of an elongated tubular member. In another aspect, the height of the peripheral portion of the diaphragm is greater than the height of the dome structure of the diaphragm at the apex of the dome structure of the diaphragm. In yet another aspect, the height of the peripheral portion of the diaphragm is approximately twice the width of the peripheral portion of the diaphragm. In another embodiment, the peripheral portion of the diaphragm is compressed by the valve housing approximately five to 15 percent. In another embodiment, a central portion of the diaphragm is subjected to moment forces from compression of the peripheral portion of the diaphragm thereby biasing the slit valve in a neutral position. In still another embodiment, a central portion of the diaphragm is positioned at a proximal end of the peripheral portion of the diaphragm. 
         [0010]    In another embodiment of the present invention, a medical device comprises a cylindrical member having a proximal end configured to be secured at a peripheral portion by a valve housing, wherein the peripheral portion has a circumference greater than the circumference of the main cylindrical member. The medical device further comprises at least one slit valve placed on an outer wall of the cylindrical member. The slit valve is oriented parallel to a longitudinal axis of the cylindrical member. In one aspect, a distal end of the valve housing is configured to attach to a proximal end of an elongated tubular member, wherein a distal portion of the elongated tubular member is configured to be placed within a portion of a patient. 
         [0011]    In a further embodiment, a medical device comprises a pressure-activated valve having an open circular proximal end and an at least partially closed distal end. The medical device is further configured such that the distal end comprises at least a partially planar surface having at least two slits oriented in different directions disposed therein. The slits have at least one common intersection and are configured to actuate in a distal direction in response to a first pressure differential. The medical device is further configured such that a portion of the distal end of the valve is defined by an interior angle of the intersecting slits, an outer portion of the distal end of the valve tapering from the distal end of the valve towards the proximal end of the valve thereby forming a channel on the outer portion of the distal end of the valve. In one aspect, the medical device further comprises at least one proximal-actuating slit valve installed on the distal end. The slit valve is configured to actuate in a proximal direction in response to a second pressure differential. In this aspect, the second pressure differential is greater than the first pressure differential. In another aspect, the slits placed in the distal end of the valve are oriented to approximate the shape of a cruciform thereby separating the distal end of the valve into quadrants. In one aspect, the valve is further configured such that the center of the cruciform is approximately collinear with the center of the circular proximal end of the valve. In yet another aspect, the at least one proximal-actuating slit valve is placed in a bottom portion of the channel. 
         [0012]    In an additional embodiment, a method is disclosed comprising the steps of placing a distal end of a catheter into a vasculature of a patient, wherein a proximal end of the catheter has a medical device connected thereto. The medical device comprises a diaphragm having at least one slit valve disposed therein and a valve housing configured to secure the diaphragm at a peripheral portion of the diaphragm. A central portion of the diaphragm is positioned relative to the peripheral portion of the diaphragm such that compressive forces acting on the peripheral portion of the diaphragm create moment forces which bias the slit valve in a neutral position. The method further comprises the steps of creating a first liquid pressure differential across the slit valve thereby infusing liquids into the patient and creating a second pressure differential across the slit valve thereby aspirating liquids from a patient. 
         [0013]    Features from any of the above-mentioned embodiments may be used in combination with one another in accordance with the instant disclosure. In addition, other features and advantages of the instant disclosure will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings, and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Advantages of the present invention will become apparent upon review of the following detailed description and drawings, which illustrate representations (not necessarily drawn to scale) of various embodiments of the invention, wherein: 
           [0015]      FIG. 1  is a front view of a patient with a catheter assembly placed within a vasculature of the patient; 
           [0016]      FIG. 2  is a perspective view of a diaphragm with a slit valve disposed therein and a valve control member; 
           [0017]      FIG. 3  is a perspective view of the diaphragm and valve control member of  FIG. 2  adjacent one another; 
           [0018]      FIG. 4  is a perspective of the diaphragm and valve control member of  FIG. 3  illustrating actuation of the valve in a distal direction; 
           [0019]      FIG. 5  is a perspective view of one embodiment of a slit valve; 
           [0020]      FIG. 6  is a perspective view of one embodiment of a slit valve; 
           [0021]      FIG. 7  is a perspective view of the slit valve of  FIG. 6  in a distally open position; 
           [0022]      FIG. 8  is a cross section view of one embodiment of a valve assembly; 
           [0023]      FIG. 9  is a cross section view of one embodiment of a slit valve; 
           [0024]      FIG. 10  is a bottom view of the slit valve of  FIG. 9 ; 
           [0025]      FIG. 11  is a cross section view of one embodiment of a slit valve; 
           [0026]      FIG. 12  is a bottom view of the slit valve of  FIG. 11 ; 
           [0027]      FIG. 13  is a cross section view of one embodiment of a slit valve; 
           [0028]      FIG. 14  is a cross section view of one embodiment of a slit valve; 
           [0029]      FIG. 15  is a cross section view of one embodiment of a valve assembly; 
           [0030]      FIG. 16  is a top view of one embodiment of a slit valve; 
           [0031]      FIG. 17  is a cross section view of the slit valve of  FIG. 16 ; 
           [0032]      FIG. 18  is a perspective view of one embodiment of a slit valve; 
           [0033]      FIG. 19  is a cross section view of the slit valve of  FIG. 18 ; 
           [0034]      FIG. 20  is a perspective view of one embodiment of a slit valve; 
           [0035]      FIG. 21  is cross section view of one embodiment of a slit valve; 
           [0036]      FIG. 22  is a cross section view of one embodiment of a slit valve; 
           [0037]      FIG. 23  is cross section view of one embodiment of a slit valve; 
           [0038]      FIG. 24  is a cross section view of one embodiment of a slit valve; 
           [0039]      FIG. 25  is cross section view of one embodiment of a slit valve; and 
           [0040]      FIG. 26  is a cross section view of one embodiment of a slit valve. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    One aspect of the instant disclosure relates to apparatuses and systems for pressure-activated valves for use with a medical device. Specifically, the instant disclosure contemplates that a slit valve may be disposed within a medical device, such as a catheter, for selective infusion and aspiration of fluids through the catheter and into a patient. 
         [0042]    Referring to  FIG. 1 , catheter assembly  10  may be of any type that can be disposed within a body cavity, duct, or vessel. Examples of such catheters include, without limitation, peripherally inserted central catheters, central venous catheters, intravenous catheters, urological catheters, as well as catheters utilized for ventilation, pleural drainage, angioplasty, or enteral feeding.  FIG. 1  illustrates a catheter  14  peripherally placed via a subclavian vein  12 . However, catheter  14  can be disposed within any portion of a patient wherein drainage, injection or aspiration of fluids, access by surgical instruments, etc. is desired. Catheter  14  comprises a first portion  15  having distal end  20  configured for placement into a portion of a patient  25  and a proximal end  30  configured for attachment to a valve assembly  35 . Catheter assembly  10  further comprises a second portion  40  having a distal end  41  configured for attachment to valve assembly  35  and a proximal end  42  configured for attachment to a fluid source  43  and a fluid removal and fluid injection location  44 . 
         [0043]    In one embodiment, fluid may be delivered via catheter assembly  10  to patient  25  via an IV bag connected to a proximal portion of the catheter assembly wherein the fluid is substantially gravity-fed to the patient  25 . In another embodiment, fluids may be power injected via the catheter assembly to the patient  25  by connecting a proximal portion of the second portion  40  of the catheter assembly  10  to a power injection system. In another aspect of the invention, fluids may be aspirated by connecting a syringe to the fluid removal location  44  and applying negative pressure to the catheter assembly  10 . 
         [0044]    Generally, one aspect of the invention contemplates a pressure-activated valve positioned in the flow path of a catheter inserted into a patient. The valve can be actuated in a distal direction by a first pressure differential, for example, gravity-induced pressure from a fluid source, such as an IV bag. The valve can also be actuated in a distal direction, for example, by power injection of contrast media into the patient. The valve can also be actuated in a proximal direction by a second pressure differential, for example, by negative pressure from a syringe thereby enabling blood withdrawal from the patient. In one embodiment, the first pressure differential is less than the second pressure differential. However, any of the pressure-activated valves disclosed herein can be reversed thereby changing the pressure differential paradigm (e.g., the first pressure differential is greater than the second pressure differential). 
         [0045]    Referring now to  FIGS. 1 through 4 , in one embodiment, a valve assembly  35  can include a diaphragm  45  with at least one slit valve  50  disposed therein and a valve control member  55  disposed adjacent the diaphragm  45 . By itself, the slit valve  50  is configured to actuate in both a proximal direction and a distal direction in response to a proximal pressure or a distal pressure, respectively. The valve control member  55  is configured to control deflection of the diaphragm  45  in a proximal direction thereby restricting actuation of the slit valve  50  in the proximal direction  57 . As a result, when the valve control member  55  is positioned adjacent the diaphragm  45 , the pressure differential which actuates the slit valve  50  in a distal direction is less than the pressure differential required to actuate the slit valve  50  in a proximal direction. In one embodiment, the diaphragm  45  is circular and the valve control member  50  is correspondingly circular. However, the diaphragm  45  and valve control member  55  can be oval, rectangular, or any other suitable shape. The valve control member  55  can be placed on a distal end of the diaphragm  45 , on a proximal end of the diaphragm  45 , or on both ends of the diaphragm  45 . 
         [0046]    In one aspect of the invention, the valve control member  55  comprises at least one arm  60  extending from an outer portion  65  of the valve control member  55  to an inner portion  66  of the valve control member  55 . In this aspect of the invention, the arm can extend laterally across a portion of the face of the diaphragm or any other angular orientation. In another embodiment, the valve control member  55  comprises a plurality of arms  60  extending from an outer portion  65  of the valve control member  55  to a center portion  66  of the valve control member  55 . In one embodiment, a single slit valve  50  is disposed substantially within the center  75  of the diaphragm  45  and is substantially linear. In another embodiment several slit valves may be disposed either centrally or about the periphery of the diaphragm. Additionally, the slit valves may have a nonlinear orientation or may comprise a plurality of interconnected linear slits oriented in different directions. 
         [0047]    Referring now to  FIGS. 1 ,  5 ,  6 , and  7 , in one embodiment, valve assembly  35  may include a pressure-activated valve  80  having an open circular proximal end  85  and an at least partially closed distal end  90 . Referring generally to  FIG. 5 , the distal end  90  of the valve  80  comprises at least a partially planar surface  82  having slit valves  95  oriented in different directions. The slits  95  have at least one common intersection  100  and are configured to actuate in a distal direction in response to a first pressure differential (e.g., less than or equal to approximately 2 psi). A portion  105  of the distal end  90  of the valve  80  is defined by an interior angle  110  of the at least two above-referenced slits  95 . An outer portion  115  of the distal end  90  of the valve  80  tapers from the distal end  90  of the valve  80  towards the proximal end  85  of the valve  80 . The tapering of the outer portion  115  of the valve  80  forms a channel  120  on the outer portion  115  of the distal end  90  of the valve  80  in the area defined by the interior angle  110  of the intersecting slits  95 . 
         [0048]    As illustrated in  FIG. 6 , in one embodiment, at least one proximal-actuating slit valve  125  can be provided on the distal end  90  of the valve  80 . The proximal-actuating slit valve  125  can be configured to actuate in a proximal direction in response to a second pressure differential (e.g., greater than or equal to approximately 2 psi), wherein the second pressure differential is greater than the first pressure differential. As depicted in  FIG. 7 , the infusion of fluids through the valve  80  results in deflection of the distal actuating valve  80 . In one embodiment, the deflection of the valve  80  in the distal direction closes the proximal-actuating valve  125 . When the pressure gradient is reversed (e.g., aspiration is underway), the proximal-actuating valve  125  is closed. In another aspect, a plurality of proximal-actuating slits  95  can be disposed on the distal end of the valve  90  oriented to approximate the shape of a cruciform. Accordingly, the distal end  90  of valve  80  is separated by the slit valves into quadrants. In one aspect of the invention, channel  120  can be formed in each quadrant of the valve  80 . Moreover, the proximal-actuating slit  125  can be disposed with the channel  120  of the valve  80 . In an additional embodiment, the valve  80  is configured such that the center  100  of the cruciform is approximately collinear with the center of the circular proximal end  85  of the valve  80 . In an additional embodiment, the sum of the arc lengths  130  of each quadrant is equal to the circumference of the proximal end  85  of the valve  80 . For example, if the arc length  130  of one quadrant is equal to 0.5 inches the circumference of the proximal end  85  of valve  80  is approximately 2 inches. 
         [0049]    Referring now to  FIGS. 8 through 10 , in one embodiment, a medical device for regulating fluid flow is disclosed comprising a valve housing  150  configured to attach to a proximal end of a catheter. The medical device further comprises a diaphragm  155  with at least one bidirectional slit valve  160  disposed therein, wherein the diaphragm approximates a dome structure  165 . The slit valve  160  may have linear or nonlinear orientations. The valve housing  150  is further configured to secure the diaphragm  155  at a peripheral portion  170  of the 20 diaphragm  155 . A central portion  175  of the diaphragm  155  is positioned relative to the peripheral portion  170  of the diaphragm  155  such that when the peripheral portion  170  is secured by the valve housing  150 , the compressive forces acting on the peripheral portion  170  create moment forces which bias the slit valve  160  in a neutral position. Despite the moment forces which bias the slit valve  160  in a neutral position, the slit valve  160  is configured to flex in a distal direction in response to pressure (e.g., a gravity-induced liquid pressure). In one embodiment, the peripheral portion  170  of the diaphragm has a height which is at least twice the width of the hinge  171  of the diaphragm  155 . In another embodiment, the height of the peripheral portion  170  is approximately twice the width of the peripheral portion. In yet another embodiment, the peripheral portion  170  is compressed by the valve housing approximately five to 15 percent. In one embodiment, the peripheral portion  170  of the diaphragm  155  has a height that ranges from approximately 0.005 inches to 0.075 inches and a thickness of the central portion  175  of the diaphragm  155  ranges from approximately 0.001 to 0.003 inches. 
         [0050]    Referring generally to  FIGS. 1 and 8  through  12 , in one embodiment, the valve housing  150  comprises a distal end  185  having a central hollow portion  190  configured to connect to a proximal end of a first portion of catheter assembly  10 , a distal end  20  of the first portion  15  of catheter assembly  10  is configured for placement into a vasculature of a patient  20 . The valve housing  150  further comprises a proximal portion  195  having a central hollow portion  200  configured to connect to a distal end  41  of a second portion  40  of catheter  10 . A proximal end  42  of the second portion  40  of catheter assembly  10  is configured to connect to a fluid source  43  and also connect to a fluid removal and fluid injection location  44 . The distal portion  185  and proximal portion  195  of the valve housing  150  mate at complimentary cut-away areas  205  securing the diaphragm  155  therebetween. All or part of the peripheral portion  170  of the diaphragm  155  may be secured by the valve housing  150  depending on the desired moment forces resulting from compression of the peripheral portion  170 . The distal portion  185  and proximal portion  195  of the valve housing  155  can be secured together through any suitable method (e.g., bonded or welded). In one embodiment, as illustrated in  FIG. 8 , the diaphragm  155  is secured such that it is perpendicular to the flow of fluid through the valve housing  150 . The diaphragm  155  may be substantially circular, oval, rectangular, or any other suitable shape. 
         [0051]    In another embodiment, the diaphragm  155  further comprises at least one arm or protrusion  210 . The protrusion  210  may be placed on a proximal end of the diaphragm  155  to assist the slit valve  160  to return to a neutral position after aspiration. When the slit valve  160  opens during aspiration, the protrusion  210  contacts the valve housing  150  thereby creating a moment force opposite the direction of contact to assist the slit valve  160  to return to a neutral position after aspiration. Multiple protrusions may be added in different embodiments on both distal and/or proximal ends of the diaphragm  155  to optimize valve function. 
         [0052]    In another embodiment, the diaphragm  155  is configured such that a portion of the proximal end of the diaphragm contiguous with the slit valve is thinner than an adjacent portion of the diaphragm. The thinner area  215  near the slit valve  160  assists in actuation of slit valve  160  as well as slit valve performance during gravity flow of fluids through the diaphragm  155 . In areas where the diaphragm is thinner, the diaphragm may be reinforced as illustrated in  FIG. 9 . The reinforced area  220  assists in returning the slit valve  160  to a neutral position by distributing moment forces coming from protrusion  210 . Additionally, the reinforced area  220  provides a secondary sealing surface  225  for an opposing valve face  230  in the event that the slit valve  160  is unable to return to a neutral position. In another aspect, the diaphragm  155  is configured such that valve hinge  171  is thinner than an adjacent portion of diaphragm  155 . The thinner area near of valve hinge  171  facilitates hinge activity under lower pressures (e.g., gravity-induced pressure). 
         [0053]    As illustrated in  FIGS. 11 and 12 , in one embodiment, the diaphragm  155  comprises a plurality of unidirectional slit valves. The diaphragm  155  can have a distal-actuating slit valve  240  disposed in a central region of the diaphragm  155  and at least one proximal-actuating slit valve  245  disposed on a lateral portion of the diaphragm  155 . The distal-actuating slit valve  240  flexes in response to infusion-induced pressures and remains closed during aspiration. The at least one proximal-actuating slit valve  245  flexes in response to aspiration-induced pressures and remains closed during infusion procedures. 
         [0054]    Referring to  FIGS. 13 and 14 , in one embodiment of the present invention, a diaphragm  250  is disclosed having at least one bidirectional slit valve  255  disposed therein. The diaphragm  250  approximates a dome structure  260 . The diaphragm  250  further comprises an annular member  265  which circumscribes the dome structure  260 . In one embodiment, the annular member  265  is oriented with its apex  270  in a proximal direction. In another embodiment, the annular member  265  is oriented with its apex  275  in a distal direction. 
         [0055]    Referring now to  FIGS. 1 and 15  through  17 , in one embodiment, a valve assembly is disclosed comprising a valve housing  300  configured to secure a diaphragm  305  at a peripheral portion  310  of the diaphragm  305 . The diaphragm  305  has at least one slit valve  315  disposed therein and is oriented within the valve housing  300  at a direction which is at an obtuse angle relative to the direction of fluid flow through the valve housing  300 . The valve housing  300  comprises a distal end  320  having a central hollow portion  325  configured to connect to a proximal end  30  of a first portion  15  of catheter assembly  10 . A distal end  20  of the first portion of catheter assembly is configured for placement into a vasculature  12  of patient  25 . The valve housing  300  further comprises a proximal portion  330  having a central hollow portion  335  configured to connect to a distal end  41  of a second portion  40  of catheter assembly  10 . A proximal end  42  of the second portion  40  of catheter assembly  10  is configured to connect to a fluid source  43  and also connect to a fluid removal and fluid injection location  44 . The distal portion  320  and proximal portion  330  of the valve housing  300  mate at complimentary cut-away areas  340  securing the diaphragm  305  therebetween. All or part of the peripheral portion  310  of the diaphragm  305  may be secured by the valve housing  300  depending on the desired moment forces resulting from compression of the peripheral portion  310 . The diaphragm  305  can have a substantially circular shape, a substantially oval shape, a substantially rectangular shape, or any other suitable shape, and can also approximate a dome structure. The distal portion  320  and proximal portion  330  of the valve housing  300  can be secured together through any suitable method (e.g., bonded or welded). In another embodiment, the surface area of diaphragm  305  subjected to pressure actuation (e.g., not in contact with any portion of the valve housing  300 ) is greater on a proximal end of the diaphragm  305  than a distal end of the diaphragm  305 . The amount of the slit valve  315  disposed in diaphragm  305  that is subject to pressure actuation (e.g., not in contact with any portion of the valve housing  300 ) is equal on both distal and proximal ends of the diaphragm  305 . This can be accomplished by varying the shape or size of the distal portion  320  and proximal portion  330  of valve housing  300 . 
         [0056]    Referring now to  FIGS. 18 and 19 , in an additional embodiment, the diaphragm narrows from a lateral portion  345  of the diaphragm  305  to an opposite lateral portion  350  of the diaphragm  305 . In another embodiment, the diaphragm  305  has two slit valves  355  disposed on opposing sides of the diaphragm  305 . Each slit valve  355  is unidirectional. A first valve is configured to actuate in a distal direction in response to an infusion-induced pressure differential. A second valve is configured to actuate in a proximal direction in response to an aspiration-induced pressure differential. The relative thickness of lateral portions of diaphragm  305  control the actuation pressure of the slit valves  355 . 
         [0057]    Referring now to  FIG. 20 , in an additional aspect, a medical device for regulating fluid flow is disclosed comprising a generally cylindrical member  370  having a closed distal end  375  and an open proximal end  380 . The proximal end  380  further comprises a shoulder member  385  configured to be secured at least partially by a valve housing. The cylindrical member  370  has at least one slit valve  390  disposed therein being oriented parallel to a longitudinal axis of the cylindrical member  370 . In another aspect, the cylindrical member  370  further comprises a plurality of slit valves  390  disposed on the cylindrical member  370 . 
         [0058]    Referring generally to  FIGS. 21 and 22 , a diaphragm  400  for regulating fluid flow is disclosed having at least one slit valve  405  disposed therein. The diaphragm  400  can be secured in a valve housing at a peripheral portion  410  of the diaphragm. In this embodiment, a proximal surface  415  of the diaphragm  400  is substantially planar. Likewise, a distal surface  420  of the diaphragm  400  is substantially planar. A central portion  420  of the diaphragm  400  is thinner than an outer region  425  of the diaphragm  400 . In another embodiment, the distal surface  430  of the diaphragm  400  is substantially planar and the proximal surface is substantially conical  435 . In another embodiment, referring generally to  FIGS. 23 and 24 , the proximal surface  440  of the diaphragm  400  is substantially planar and the distal surface of the diaphragm  400  approximates a spherical cap  445 . In another embodiment, the distal surface  450  of the diaphragm  400  approximates a spherical cap and the proximal surface  455  of the diaphragm  400  also approximates a spherical cap. The virtual centers of the opposing spherical caps of the diaphragm  400  can be collinear. The spherical cap on the distal surface  455  can be smaller than the spherical cap on the proximal surface  450 . In yet another embodiment, referring generally to  FIGS. 25 and 26 , a proximal surface  460  of the diaphragm  400  is substantially conical. The distal surface  465  of the diaphragm  400  is also substantially conical. 
         [0059]    The diaphragms discussed herein can be molded in one piece from an elastomeric material (e.g., a silicone rubber having a Shore A Durometer rating from about 30 to 60). It should be noted that any of the diaphragms discussed herein can be manufactured from any elastomeric material including, without limitation, polyisoprene, butyl rubber, halogenated butyl rubbers, polybutadiene, styrene-butadiene rubber, nitrile rubber, hydrated nitrile rubbers, Therban® elastomer, Zetpol® elastomer, chloroprene rubber, polychloroprene, neoprene, baypren, EPM (ethylene propylene rubber, a copolymer faeces of polyethylene and polypropylene), EPDM rubber (ethylene propylene diene rubber, a terpolymer of polyethylene, polypropylene and a diene-component), epichlorohydrin rubber, polyacrylic rubber, fluorosilicone rubber, fluoroelastomers, Viton® elastomer, Tecnoflon® elastomer, Fluorel® elastomer, Dai-El® elastomer, perfluoroelastomers, tetrafluoro ethylene/propylene rubbers, chlorosulfonated polyethylene, Hypalon® elastomer, ethylene-vinyl acetate, Hytrel® elastomer, Santoprene® elastomer, polyurethane rubber, resilin, elastin, and/or Polysulfide rubber. 
         [0060]    The valve housings discussed herein can be molded in one or more pieces from a thermoplastic material (e.g., a polyethylene terephthalate having a Shore A Durometer rating from about 60 to 85). It should be noted that any of the valve housings discussed herein can be manufactured from any thermoplastic material including, without limitation, acrylonitrile butadiene styrene, acrylic, celluloid, cellulose acetate, ethylene-vinyl acetate, ethylene vinyl alcohol, fluoroplastics, ionomers, polyacetal, polyacrylates, polyacrylonitrile, polyamide, polyamide-imide polyaryletherketone, polybutadiene, polybutylene, polybutylene terephthalate, polyethylene terephthalate, polycyclohexylene dimethylene terephthalate, polycarbonate, polyhydroxyalkanoates, polyketone, polyester, polyethylene, polyetheretherketone, polyetherimide, polyethersulfone, polyethylenechlorinates, polyimide, polylactic acid, polymethylpentene, polyphenylene oxide, polyphenylene sulfide, polyphthalamide, polypropylene, polystyrene, polysulfone, and/or polyvinyl chloride. 
         [0061]    Any of the catheters described herein can be manufactured from any biocompatible material suitable for placement into a portion of a patient. 
         [0062]    Although the above-described embodiments show a particular configuration of a pressure-actuated valve and valve assembly, such embodiments are exemplary. Accordingly, many different embodiments are contemplated and encompassed by this disclosure. It should also be understood that the device and method for controlling fluid flow through a catheter can be used with any method or device wherein fluids are administered to or removed from a patient. 
         [0063]    While certain embodiments and details have been included herein for purposes of illustrating aspects of the instant disclosure, it will be apparent to those skilled in the art that various changes in the systems, apparatuses, and methods disclosed herein may be made without departing from the scope of the instant disclosure, which is defined, in part, in the appended claims. The words “including” and “having,” as used herein including the claims, shall have the same meaning as the word “comprising.”