Abstract:
A system for selectively preventing free flow in a tube includes an in-line occluder disposed in the tube and an actuator pad for creating a flow path between the tube and the occluder. The actuation pad presses towards the occluder from a single side and stretches the tube to create a large flow path. The occluder stem is strengthened to resist deformation and damage from the forces applied by the actuator pad.

Description:
PRIORITY 
       [0001]    The present application claims the benefit of U.S. Provisional Application Ser. No. 61/388,901, filed Oct. 1, 2010 which is herein incorporated by reference in its entirety. 
     
    
     THE FIELD OF THE INVENTION 
       [0002]    The present invention relates to preventing undesired flow through tubing. More specifically, the present invention relates to preventing free flow and undesired flow in infusion tubing such as may be used for delivering nutritional feeding via a pump while selectively allowing flow through the infusion tube as desired. 
       BACKGROUND 
       [0003]    Fluid delivery pumps are used for a variety of different purposes. Medical fluids are frequently delivered via a peristaltic pump. In medical applications, it is particularly important to control the fluid flow through the delivery tubing. Where medicine or nutritional fluids are delivered through the tubing, it is typically important to control the volume of fluid delivered as well as the rate of delivery. Unintended flow through the delivery tubing can result in inaccurate fluid delivery and can cause health problems for the patient in some cases. 
         [0004]    In order to prevent unintended flow through medical delivery tubing, occluders are often used to selectively prevent flow through the tubing. The occluder is opened when it is desired to allow flow through the tubing. Available in-line occluders and the associated systems for allowing flow through the tubing and past the occluder suffer from several problems. One problem is the difficulty for a person to manually prime the delivery tubing in order to remove air from the tubing and fill the tubing with the liquid before using the delivery tubing in a pump to deliver fluid to a person. In-line occluders in particular have been difficult for persons to actuate to manually prime delivery tubing. While the person may load the delivery tubing into the pump and use the pump to advance the fluid, the pump delivers fluid at a slow rate and it can take quite a long time to do so. In emergencies, such a time delay may not be desirable. Additionally, the attending person may begin to perform other tasks while priming the pump and neglect to adequately monitor the pump while priming. 
         [0005]    Another problem with occluders is that the actuators or systems used to open a flow passage past the occluder have proven somewhat inconsistent in their performance, and may not open a sufficiently large flow passage to not restrict flow. Restrictions in flow may affect the accuracy of the delivered fluid or the ability to monitor the fluid flow. The performance of available in-line occluders is limited both by the strength and design of the occluder as well as by the design of the actuator element used to create a flow path past the occluder. 
         [0006]    Another problem is the reliability of the pump structures used to open a flow channel past the occluder once the occluder is properly loaded into a delivery pump. Prior art structures have been used to create a flow channel past the occluder, but these structures have often worked inconsistently or opened a flow passage which is insufficiently large for proper flow. 
         [0007]    There is a need for an improved in-line occluder and actuator system for selectively allowing flow past the occluder. There is a need for an occluder and actuator system which opens a larger flow path past the occluder and which reliably opens and closes the flow path. There is a need for an occluder and actuator system which reliably integrates with a pump, allowing the pump door to open a flow past the occluder when the door is closed. There is a need for an occluder and actuator system which allows a person to manually open a flow passage past the occluder easily and consistently. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to provide an improved in-line occluder and actuator system for selectively allowing flow past the occluder. 
         [0009]    According to one aspect of the invention, a fluid delivery cassette is provided which has an occluder and infusion tubing, and which has an actuator formed as a part of the cassette. The actuator allows a person to manually allow flow past the occluder quickly and reliably. The person may thus manually prime the tubing before loading the tubing into a pump or allow fluid to flow through the tubing by gravity. 
         [0010]    According to one aspect of the invention, an occluder and actuator are provided which allow for a large flow channel to be opened past the occluder. An actuator design is provided which pushes and stretches the pump tubing to one side of the occluder and opens a single large flow passage past the occluder. An occluder is provided which has been significantly strengthened to resist bending and breaking when a large force is applied to the occluder by the actuator. 
         [0011]    According to another aspect of the invention, a delivery cassette and pump are provided where the pump door interacts with the actuator assembly of the cassette to open flow past the occluder when the cassette is properly loaded and when the door is closed. 
         [0012]    These and other aspects of the present invention are realized in an in-line occluder and actuator system as shown and described in the following figures and related description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Various embodiments of the present invention are shown and described in reference to the numbered drawings wherein: 
           [0014]      FIGS. 1A and 1B  show perspective views of a pump and infusion cassette of the present invention; 
           [0015]      FIGS. 2A through 2D  show perspective and top views of the infusion cassette; 
           [0016]      FIGS. 3 through 5  show partial cross-sectional side views of the occluder and actuator pad of the infusion cassette; 
           [0017]      FIGS. 6 through 8B  show partial cross-sectional end views of the occluder and actuator pad; 
           [0018]      FIGS. 9 through 13  show additional views of the occluder and stem; 
           [0019]      FIGS. 14 and 15  show partial views of the pump, cassette, and pump door; and 
           [0020]      FIGS. 16 and 17  show partial perspective views of the pump and cassette. 
       
    
    
       [0021]    It will be appreciated that the drawings are illustrative and not limiting of the scope of the invention which is defined by the appended claims. The embodiments shown accomplish various aspects and objects of the invention. It is appreciated that it is not possible to clearly show each element and aspect of the invention in a single figure, and as such, multiple figures are presented to separately illustrate the various details of the invention in greater clarity. Similarly, not every embodiment need accomplish all advantages of the present invention. 
       DETAILED DESCRIPTION 
       [0022]    The invention and accompanying drawings will now be discussed in reference to the numerals provided therein so as to enable one skilled in the art to practice the present invention. The drawings and descriptions are exemplary of various aspects of the invention and are not intended to narrow the scope of the appended claims. 
         [0023]    Turning now to  FIG. 1A , a perspective view of a pump  10  and infusion cassette  14  of the present invention is shown. The pump  10  is a peristaltic pump typically used for medical applications such as drug delivery, IV applications, or feeding. The pump  10  includes a pumping rotor  18 , various structures  22  to locate and secure the infusion cassette  14 , and auxiliary devices such as pressure sensors and air bubble detectors as are necessary for the application. The infusion cassette  14  includes a cassette body  24  and pumping tubing  26  which is wrapped around the pump rotor  18 . The cassette body  24  is attached to inflow tubing  30  which is connected to a fluid supply, and outflow tubing  34  which is connected to a patient. The pump tubing  26  is typically flexible silicone tubing. The inflow tubing  30  and outflow tubing  34  are typically vinyl tubing. 
         [0024]    The cassette body is formed with an in-line occluder to prevent uncontrolled flow through the pump tubing  26 . To improve the ease of use of the cassette  14 , the cassette body has a priming arm  66  which is disposed adjacent the occluder. The priming arm includes an actuator pad  70  which interacts to allow flow past the occluder  62 . The side of the actuator pad  70  which faces towards the occluder  62  has an engagement surface for engaging the tubing  26  and allowing flow past the occluder. The side of the actuator pad  70  which faces away from the occluder  62  includes a rounded finger depression  72  which receives the finger or thumb of a user to allow the user to manually open a flow passage past the occluder  62 . The priming arm may be used to manually prime the cassette  14  before loading the cassette into the pump  10 , and also interacts with the pump  10  to allow flow past the occluder once the cassette  14  is properly loaded in the pump. 
         [0025]    The pump  10  includes a door  126  which is attached to the pump  10  via a hinge. The door includes a latch  134  which interacts with the pump to hold the door closed, and also includes a projection  142  which interacts with the priming arm  66  to open a flow passage past the occluder  62 . The pump  10  includes a door support post  42  which interacts with the pump door projection  142  to allow flow past an occluder  62  which is part of the cassette body  24  after the pump door is closed. The door support post  42  is disposed adjacent the actuator pad  70  with a space therebetween. The projection  142  fits between the support post  42  and the actuator pad  70  and, when placed therebetween, forces the actuator pad  70  towards the occluder  62  to engage the tubing  26  and open a flow passage past the occluder. 
         [0026]      FIG. 1B  shows the pump  10  with the door  126  in a closed position. In this position, the projection  142  has engaged the door support post  42  and the actuator pad  70  to press the actuator pad against the tubing  26  and create a flow passage between the occluder  62  and the tubing  26 . 
         [0027]      FIGS. 2A and 2B  show perspective views of the cassette  14 .  FIG. 2C  shows a top view of the cassette  14 .  FIG. 2D  shows a partial perspective view of the cassette occluder and priming arm. The cassette  14  is a unitary, one-piece structure having the various parts such as the cassette body, occluder, connectors and actuator arm as discussed herein. The cassette body  24  connects the inflow tubing  30 , outflow tubing  34  and pump tubing  26 . As seen, a first side  24   a  of the cassette body  24  forms a first connector  46  which receives the inflow tubing  30  and a first end of the pump tubing  26 . A second side  24   b  of the cassette body  24  forms a second connector  50  which receives the outflow tubing  34  and a second end of the pump tubing  26 . The body  24  connects the first connector  46  and second connector  50  together, the first and second connectors being disposed generally parallel to each other and separated laterally by the body. The pump tubing  26  is held in a loop and is placed around the pump rotor. The first connector  46  has a cylindrical or barbed body  52  which holds the pump tubing  26 . The second connector  50  has a cylindrical body  54 , a stem  58  attached to the body, and an occluder  62  which is attached to the stem so that the stem spaces the occluder apart from the body. The body  54 , stem  58  and occluder  62  are placed in the bore of the pump tubing  26 . The first connector body  52  and second connector body  54  are larger than the tubing bore and grip the tubing. The occluder  62  is slightly larger in diameter than the pump tubing bore so that the occluder seals against the bore and, in this state, prevents flow through the pump tubing. 
         [0028]    A priming arm  66  is disposed adjacent the body  54  and occluder  62 . As shown, the priming arm  66  extends generally parallel to the body  54  and occluder  62 . The priming arm  66  has an actuator pad  70  formed on the end of the arm  66 . The actuator pad  70  is adjacent the occluder  62  so that when the priming arm  66  is bent inwardly towards the occluder  62  the actuator pad contacts the pump tubing  26  which is laterally adjacent to the occluder. The side of the actuator pad  70  which faces the occluder  62  is formed with two rounded projections  74  disposed longitudinally adjacent the occluder  62 , a tip portion  78  disposed slightly upstream from the occluder  62 , and a channel  82  extending longitudinally along the actuator pad  70  and between the projections  74 . As the actuator pad  70  is pressed against the pump tubing  26 , a flow channel is opened between the occluder  62  and the pump tubing. The side of the actuator pad  70  which is opposite the occluder  62  has a rounded depression  72  for receiving the finger or thumb of a user. This makes the actuator more intuitive for manual priming of the infusion cassette  14  and reduces the likelihood that the user&#39;s finger or thumb slips while manually allowing flow past the occluder.  FIGS. 2B and 2C  better illustrate the finger depression  72  as well as other aspects of the cassette  14 . 
         [0029]      FIGS. 3 through 5  show side views of the occluder  62  and priming arm  66  moved through various stages of actuation in order to allow flow past the occluder. The connector body  54  is inserted into the pump tubing  26 . As shown, the connector body  54  has a bore  86  therethrough. The stem  58  is formed with a ‘T’ shaped cross section. The stem  58  has a side wall disposed perpendicular to the movement of the priming arm  66  and a web disposed parallel to the movement of the priming arm. The side wall and web extend longitudinally from the body  54  and connect the body  54  and occluder  62  to each other. The occluder  62  has a cylindrical shape with two ribs  90  formed thereon and a tapering front portion. The ribs  90  engage the bore of the pump tubing  26  to form a seal and prevent flow through the pump tubing. The end  94  of the occluder  62  tapers to a smaller diameter, allowing the pump tubing  26  to bend sideways to better open a flow channel through the tubing. When a flow path is opened, fluid flows between the occluder  62  and the tubing wall, around the stem  58 , and through the bore  86  in the connector body  54 . 
         [0030]    It can be seen how, according to a preferred embodiment, the projections  74  on the actuator pad  70  are slightly upstream of the occluder ribs  90 ; the downstream edge of the projections  74  being aligned with the upstream rib  90 . In other words, the proximal (relative to the connection of the priming arm  66  to the cassette body  24 ) side of the projections  74  is aligned with the distal rib  90 . This arrangement between the projections  74  and occluder  62  places the projections  74  over both of the ribs  90  when the priming arm  66  bends inwardly to open a flow channel past the occluder. The tip portion  78  of the actuator pad  70  is upstream of the projections  74 . The tip portion  78  of the actuator pad  70  does not extend towards the tubing  26  as far as the projections  74 . The channel  82  extends longitudinally along the actuator pad  70 , extending between the projections  74  and along the tip portion  78 . The channel aids in bending and positioning the tubing  26  when the priming arm  66  is pressed against the tubing. 
         [0031]      FIG. 4  shows the actuator pad  70  pressed against the pump tubing  26 . The actuator pad  70  is moved partially between the first non-engaging rest position shown in  FIG. 3  and the second fully engaging actuated position shown in  FIG. 5 . The projections  74  engage the pump tubing  26  as the actuator pad  70  is moved inwardly as shown. This causes the portion of the pump tubing  26  between the projections  74  to become stretched and pushes the pump tubing away from the actuator pad  70 , causing a flow passage  98  to open between the occluder  62  and the pump tubing  26 . Once a flow passage  98  has been opened, fluid may flow between the pump tubing  26  and the occluder  62 , past the stem  58 , and through the bore  86  in the body  54 . 
         [0032]      FIG. 5  shows the actuator pad  70  moved into the second actuated position. It can be seen how the projections  74  are now positioned over the ribs  90 . The projections  74  have further stretched the portion of the pump tubing  26  between the projections, and have formed a larger flow passage  98  between the pump tubing  26  and the occluder  62 . When the actuation pad  70  is in the second position as shown, the tip  78  of the actuation pad  70  contacts the pump tubing  26  and presses a portion of the pump tubing which is upstream from the occluder laterally, displacing the pump tubing in the direction of movement of the priming arm  66 . This displacement of the pump tubing  26  is shown in comparison to the dashed pump tubing portion  26   a  which indicates the original un-displaced position of the pump tubing  26 . 
         [0033]    The actuator pad  70  thus engages the pump tubing  26  in two different manners in order to more effectively create a flow passage  98 . The projections  74  stretch the pump tubing  26  around the occluder  62  and push the pump tubing away from the actuation pad and the tip  78  of the actuation pad also presses on the pump tubing upstream from the occluder to further move the pump tubing away from the actuation pad  70 . The combined stretching and displacement of the pump tubing  26  creates a large flow passage  98  between the pump tubing and the occluder  62 . The actuator pad  70  thus provides a significant improvement over previous methods of creating a flow passage past the occluder  62  by opening a significantly larger flow passage  98  and by more reliably creating the flow passage. It can also be seen how, when the priming arm  66  is fully pressed against the tubing  26 , the projections  74  are disposed adjacent both of the ribs  90 . 
         [0034]      FIG. 6  shows an end view of the occluder  62  and actuator pad  70  in the first, non-actuating position (as shown in  FIG. 3 ). The shape of the actuator pad  70  can more readily be seen. As has been discussed, the cassette  14  is often used for medical applications such as delivering feeding solutions. As such, the occluder  62  is often about one eighth of an inch in diameter. The bore of the pump tubing  26  is slightly smaller than the diameter of the occluder  62  so that the occluder seals against the pump tubing. The functional portion of the actuator pad  70 , as discussed, is largely defined by the projections  74 , the channel  82  and the tip portion  78 . The actuator pad functional surfaces include the radiused ends  102  of the projections  74 , the radiused channel  82 , and relatively flat surfaces  106  connecting the radiused ends  102  and the channel  82 . 
         [0035]    According to a preferred embodiment, the radiused ends  102  of projections  74  have a radius of curvature which is approximately equal to the radius of the occluder  62  and occluder ribs  90  (as the occluder ribs are relatively small). It is currently preferred that the channel  82  have a radius of curvature which is also approximately equal to the radius of the occluder  62 . The flat surfaces  106  connecting the radiused ends  102  and the surface of the channel  82  are disposed at a slight angle to each other such that they form a slot between the projections which tapers and is narrower at the bottom than at the top. The flat surfaces may be disposed at an angle of about 5 to 25 degrees relative to each other. It is currently preferred that the flat surfaces  106  are disposed at an angle which is between about 15 and 20 degrees relative to each other; with an angle of about 18 degrees being currently preferred. For ease of molding the actuator pad  70 , it is currently preferred that the radiused ends  102 , flat surfaces  106  and channel  82  are flat longitudinally along the axis of the occluder  62 . The surfaces  78   a  of the tip portion  78  which face towards the occluder  62  are typically flat for ease of manufacture. 
         [0036]    The shape of the actuator pad  70  allows for the formation of a large flow passage  98 , and allows the occluder to reliably seal against the tubing  26  when the actuator pad  70  is not pressed against the tubing  26 . The radiused ends  102  of the projections  74  allow the projections to push into the pump tubing  26  slightly and to grip the pump tubing well as the actuation pad  70  engages the pump tubing. As the actuation pad  70  moves further towards the occluder  62 , the pump tubing  26  is engaged by the flat surfaces  106  which more tightly grip the pump tubing and allow for a higher degree of stretching to occur to the portion of the pump tubing which is between the projections  74 . The angle formed between the flat surfaces  106  both allows these flat surfaces  106  to more tightly grip the pump tubing  26  as the pump tubing is pushed closer to the channel  82 , and also allow the occluder  62  and pump tubing  26  to be easily released from between the projections  74  when the actuation pad  70  is no longer pushed towards the occluder  62 , making the occluder more reliable. 
         [0037]    The contact surfaces of the actuation pad  70  which engage the tubing adjacent the occluder  62  form an actuation channel  110  which engages the pump tubing  26 . The actuation channel  110  is formed by the radiused ends  102 , flat surfaces  106  and curved channel  82 . The actuation channel curves outwardly at the top (in the area of radiused ends  102 ) to better grip the tubing  26  as the occluder  62  is forced into the actuation channel  110 . The actuation channel  110  is also tapered so that it gets progressively narrower as the occluder  62  is pressed deeper into the channel, increasing the grip on the pump tubing  26  and better stretching and moving the pump tubing to form a flow passage  98 . The bottom of the actuation channel  110  is formed by curved channel  82 . The bottom of the actuation channel  110  limits how deep the occluder  62  can slide into the channel, eliminating the possibility that the occluder and pump tubing  26  can become stuck in the actuation channel  110  and ensuring that the occluder and pump tubing easily exit the channel when the actuation pad  70  is not pressed against the occluder  62 . 
         [0038]      FIG. 7  shows an end view of the actuation pad  70  and occluder  62  in the intermediate actuation position which is shown in  FIG. 4 . It can be seen how the projections  74  engage the pump tubing  26  and, by stretching and pushing the pump tubing, form a flow passage  98  between the pump tubing and occluder  62 . 
         [0039]      FIG. 8  shows another end view of the actuation pad  70  and occluder  62  in the second, actuating position shown in  FIG. 5 . It can be seen how the occluder  62  is moved between the projections  74 . The radiused ends  102  of the projections and the tapering channel formed by the flat surfaces  106  has stretched the portion of the pump tubing  26  which is between the projections  74 , pushing the pump tubing outwardly and making a large flow passage  98  between the pump tubing and the occluder  62 . The actuation pad  70  can also be pressed further against the occluder  62  and tubing  26 , contacting the tubing  26  against the bottom of the channel  82 . Although not necessary, this can hold the tubing  26  securely while forming a flow channel  98 . It is thus seen how the actuation channel  110  has a shape which has been found to maximize the reliability of the occluder and to open a large flow path past the occluder when desired. 
         [0040]      FIG. 8B  shows another end view of an actuation pad  70  which functions similarly to that of the remaining figures. Unless discussed otherwise, the actuation pad  70  of  FIG. 8B  is used with the other structures and features of the pump and cassette as discussed with respect to the other figures. The actuation pad  70  varies in that the projections  74  are extended and do not have a rounded front end. Rather, the projections form a deeper actuation channel  110 . The actuation channel tapers, being wider near the opening and narrower near the bottom of the actuation channel. The side surfaces  106  of the actuation channel  110  are disposed at an angle of approximately 18 degrees relative to each other. When the actuation pad  70  is forced towards the occluder  62 , the pump tubing  26  is stretched and pushed to form a flow passage  98  as discussed. 
         [0041]    The actuator pad  70  of  FIGS. 6-8  (and the other figures of the application) has been found to be advantageous over a more simple actuation pad as shown in  FIG. 8B , however. The actuation pad  70  of  FIGS. 6-8 , because of the curved ends  102  of the projections  74 , does not require as much lateral movement as the actuation pad of  FIG. 8B  and releases and grips the projection better, increasing the reliability of the actuator pad  70  as used to prime the infusion cassette and allow flow past the occluder. 
         [0042]      FIGS. 9 through 13  show detailed views of the occluder stem  58 .  FIG. 9  shows a view of the stem  58  with the actuation pad  70  included for reference.  FIG. 10  shows a view from the side of the stem  58  opposite the actuation pad.  FIGS. 11 through 13  show cross-sectional views taken along lines A-A, B-B and C-C of  FIG. 9 . The occluder body  54 , stem  58  and occluder  62  are shown. The actuation pad  70  is shown for reference to indicate how force is applied to the occluder  62 . In order to reliably create a large flow passage  98 , the actuator pad  70  places a large lateral force on the occluder  62 . Stem  58  provides increased unidirectional bending strength while still providing an adequate flow path around the stem  58 . The stem  58  has a generally ‘T’ shaped cross section. 
         [0043]    The stem  58  includes a center web  114  extending across the center and side of the stem sway from the actuator pad  70  and includes a side wall  118  disposed perpendicular to the center web on the side of the stem which is adjacent the actuator pad. The side wall  118  is disposed perpendicular to the direction of movement of the actuation pad  70  in engaging the occluder  62  and the web  114  is disposed parallel to the direction of movement of the actuation pad  70 . Thus, when the actuator pad  70  presses against the occluder  62 , the side wall  118  is placed in tension and the center web  114  is largely placed in compression. An opening  122  is formed adjacent the base of the stem  58 . The opening  122  extends parallel to the side wall  118 . The opening  122  connects the bore  86  of the cylindrical body  54  to the space adjacent the center web  114 . When a flow passage  98  is opened between the occluder  62  and the pump tubing  26 , fluid is able to flow past the occluder, around and adjacent to the center web  114 , through opening  122  and into the bore  86 . The ‘T’ shaped stem  58  and the design of the fluid pathway through the stem achieves a stem  58  which provides increased strength while still maintaining an adequate fluid flow path which does not overly restrict flow. The ‘T’ shaped stem  58  has shown an increased resistance to bending and breaking under the elevated lateral forces which are applied by the actuator pad  70 . 
         [0044]      FIG. 11  better shows the internal structure of the stem  58 . It can be seen how the fluid is able to flow past the center web  114 , through the opening  122 , and into the bore  86 .  FIG. 12  shows how the opening  122  passes laterally through the end of the cylindrical body  54 , leaving broad solid body portions  54   a  to support the stem  58 . The stem  58  eliminates thin elongate sections of material which allow for bending, deflection and breakage.  FIG. 13  shows how the center web  114  and side wall  118  are arranged in a ‘T’ shape. The side wall  118  has a rounded outer surface. 
         [0045]      FIG. 14  shows a partial cross-sectional view of the pump  10 , actuation pad  70 , occluder  62 , door support post  42  and pump door  126 . For clarity, not all structures of the pump  10  or cassette  14  are shown. The pump door  126  attaches to the pump  10  via a hinge  130  on one side of the pump and door and with a mating latch or catch  134  and receptacle  138  on the other side of the pump and door. The door  126  has a projection  142  formed thereon. The projection  142  has an engagement surface  146  with a curved lower portion  150  which curves away from the engagement surface towards the bottom thereof. The engagement surface  146  contacts the back side  154  of the actuator pad  70  opposite the actuation channel  110 . The back side  154  of the actuator pad  70  has a curved upper portion  158 . 
         [0046]    When the door is closed, the engagement surface  146  contacts the back side  154  of the actuator pad  70  and pushes the actuator pad  70  into the occluder  62  and pump tubing  26  in the manner discussed above to open a flow path  98  past the occluder. Initially, the curved lower portion  150  of the engagement surface  146  contacts the curved upper portion  158  of the back side  154  of the actuator pad  70  and the angular relationship therebetween causes the actuator pad  70  to move sideways as the projection  142  moves down. 
         [0047]    Once the pump door  126  is closed, as is shown in  FIG. 15 , the flat, vertical portion of the projection contact surface  146  and of the back side  154  of the actuator pad  70  are in contact, eliminating any tendency of the actuator pad  70  to push the door open. The door support post  42  contacts the side of the projection  142  which is opposite the actuator pad  70  and prevents the actuator pad  70  from bending the door and pushing the projection  142  horizontally away from the actuator pad  70 . 
         [0048]      FIGS. 16 and 17  show partial perspective views of the pump  10  and cassette  14 , highlighting additional details of the door support post  42 . For clarity, many structures of the pump  10  and cassette  14  are not shown. The door support post  42  is preferably formed with a contact surface  162  which faces towards the actuator pad  70  and which contacts the projection  142  as discussed previously. The contact surface  162  is curved side to side as shown so as to center the projection  142  over the contact surface  162  and thereby increase the reliability of creating a flow passage  98  between the occluder  62  and pump tubing  26 . The contact surface  162  is also disposed at an angle relative to the pump  10  such that the top of contact surface is farther away from the actuation pad  70  than the bottom of the contact surface. Thus, the contact surface  162  may be disposed at an angle of about 10 to 20 degrees from perpendicular. 
         [0049]    Disposing the contact surface  162  at an angle off of perpendicular causes the projection  142  to move inwardly towards the actuation pad  70  as the door  126  is being closed and thereby increases the amount by which the actuation pad  70  may be displaced sideways while simultaneously reducing the likelihood that the door support post  42 , projection  142  and actuation pad  70  bind and malfunction while closing the door. Thus, sloping the contact surface  162  results in a more reliable and better functioning system for opening a flow passage past the occluder  62  while simultaneously allowing a larger flow passage to be opened. 
         [0050]    It will be appreciated that the present invention may include various features discussed above. For example, an in-line occluder in accordance with one aspect of the invention may include: a flexible tubing having a bore; an occluder disposed in the bore, the occlude having: a body; an occluder, the occluder having a round cross-section and engaging the bore of the tubing to seal against the tubing and prevent flow past the tubing; and a stem connecting the body to the occluder, the stem having a ‘T’ shaped cross section. The occlude may also include: the stem having a side wall disposed along a side of the stem and a center web attached to the middle of the side wall and extending perpendicular thereto towards an opposite side of the stem; the body having a longitudinal bore extending along the length thereof and a lateral bore extending laterally through and end of the body adjacent the stem; the lateral bore extends generally perpendicular to the center web; a configuration such that fluid flows between the occluder and the tubing, around the center web, and through the body; an actuator pad disposed adjacent the occlude such that the actuator pad presses inwardly on an outer surface of the tubing on one side of the tubing to open a flow passage between the occluder and an opposite side of the tubing; the actuator pad having two projections having curved ends and an actuation channel disposed between the two projections, and wherein the actuator pad engages the tubing between the two projections and presses the tubing and occluder towards the actuation channel; the actuation channel tapering such that a bottom of the channel is narrower than a top of the channel; the two projections having a radius of curvature approximately equal to the radius of the occluder, and the actuation channel having a width approximately equal to the diameter of the occlude; the actuator pad being connected to the occlude; a pump having a pump door such that the occluder and actuator pad are mounted in the pump and the pump door engages the actuator pad to press the actuator pad against the tubing to open a flow channel past the occlude; and/or a projection on the pump door moves in a first direction when the door is closed and wherein the projection engages the actuator pad and presses the actuator pad in a second direction perpendicular to the first direction to thereby press the actuator pad against the tubing; or combinations thereof. 
         [0051]    An occluder system of the present invention may include; a flexible tubing having a lumen; an occluder having: a body; a stem having a first end and a second end, the first end being attached to the body; and an occluder attached to the second end of the stem and spaced apart from the body, the occluder being disposed in the lumen of the tube and having a round cross-section with a diameter greater than the diameter of the lumen; an actuator pad, the actuator pad having: two projections; and an actuation channel disposed between the two projections; and wherein the actuation pad selectively engages the tubing on one side of the tubing to create a flow passage between the occluder and an opposite side of the tubing. 
         [0052]    The occluder system of the previous paragraph may also include: the two projections having curved ends; the two projections each having a radius of curvature which is approximately equal to the radius of the occlude; the actuation channel having a width approximately equal to the diameter of the occlude; the actuation channel tapering such that a top of the action channel is wider than a bottom of the actuation channel; a top portion of the actuation channel transitioning into the curved ends such that the curved ends curve away from the actuation channel; the actuation channel having a rounded bottom; the actuator pad being movable towards the occluder to engage the tube and open a flow channel between the occluder and the tube; the actuator pad being attached to the occluder and is pivotable towards the occlude; the actuator pad having a recessed tip portion adjacent the projections such that the tip portion contacts the tube to displace the tube laterally when the actuator pad engages the tube to open a flow passage; the actuation channel being tapered so as to be narrower at the bottom; and/or the actuation channel tapering between 5 and 20 degrees; or combinations thereof. 
         [0053]    There is thus disclosed an improved anti free-flow occluder and actuator pad. It will be appreciated that numerous changes may be made to the present invention without departing from the scope of the claims.