Abstract:
A disposable wearable infusion device comprises a reservoir that holds a liquid medicament and a cannula having a distal end that delivers the liquid medicament to a patient The device further comprises a pump that displaces a volume of the liquid medicament along a path to the cannula when actuated and a lock-out that precludes actuation of the pump when an occlusion occurs within the path to the distal end of the cannula.

Description:
BACKGROUND OF INVENTION 
     The present invention relates to infusion devices and more particularly to such devices that enable liquid medicaments to be conveniently and safely self-administered by a patient. 
     Administration of insulin has traditionally been accomplished using a syringe. Recently, needle carrying pen-like devices have also been employed for this purpose. Both forms of insulin administration require the patients to stick themselves each time they inject insulin, often many times a day. Thus, these traditional forms of insulin administration have been a rather pervasive intrusion in the lives and routines of the patient&#39;s who have had to adopt and employ them. 
     More recently, insulin pumps attached by tubing to an infusion set mounted on the patient&#39;s skin have been developed as an alternative form of insulin administration. Such pumps may be controlled by a programmable remote electronic system employing short range radio communication between a control device and electronics that control the pump. While such devices may involve fewer needle sticks, they are expensive to manufacture. They are also complex to operate and cumbersome and awkward to wear. Further, the cost of such devices can be many times the daily expense of using a traditional injection means such as a syringe or an insulin pen. 
     Devices of the type mentioned above also require a significant amount of training to control and thus use the devices. Great care in programming the devices is required because the pumps generally carry sufficient insulin to last a few days. Improper programming or general operation of the pumps can result in delivery of an excessive amount insulin which can be very dangerous and even fatal. 
     Many patients are also reluctant to wear a pump device because they can be socially awkward. The devices are generally quite noticeable and can be as large as a pager. Adding to their awkwardness is their attachment to the outside of the patients clothes and the need for a catheter like tubing set running from the device to an infusion set located on the patient&#39;s body. Besides being obvious and perhaps embarrassing, wearing such a device can also be a serious impediment to many activities such as swimming, bathing, athletic activities, and many activities such as sun bathing where portions of the patient&#39;s body are necessarily uncovered. 
     In view of the above, a more cost effective and simple device has been proposed whereby an injection system is discreetly attached directly to the skin of the patient. The device may be attached to the patient under the patient&#39;s clothing to deliver insulin into the patient by the manual pumping of small doses of insulin out the distal end of a temporarily indwelling cannula that is made a part of the pump device. The cannula may be made a part of the drug delivery device before, during or after the attachment of the drug delivery device to the skin of the patient. The device may be made quite small and, when worn under the clothes, entirely unnoticeable in most social situations. It may still carry sufficient insulin to last a patient several days. It can be colored to blend naturally with the patient&#39;s skin color so as not to be noticeable when the patient&#39;s skin is exposed. As a result, insulin for several days may be carried by the patient discreetly, and conveniently applied in small dosages after only a single needle stick. For a more complete description of devices of this type, reference may be had to co-pending application Ser. No. 11/906,130, filed on Sep. 28, 2007 for DISPOSABLE INFUSION DEVICE WITH DUAL VALVE SYSTEM, which application is owned by the assignee of this application and hereby incorporated herein by reference in its entirety. 
     The present invention provides further improvement to the devices disclosed in the above referenced co-pending application. More particularly, the devices disclosed herein provide for improved patient safety and/or convenience. For example, embodiments of the invention provide, for example, improved sealing of the medicament, more convenient cannula deployment, device misuse prevention, primed and dosage ready indication and fluid path occlusion detection. These and other advantages are addressed herein. 
     SUMMARY OF THE INVENTION 
     A disposable wearable infusion device comprises a reservoir that holds a liquid medicament, a cannula having a distal end that delivers the liquid medicament to a patient, a pump that displaces a volume of the liquid medicament along a path to the distal end of the cannula when actuated, and a lock-out that precludes actuation of the pump when an occlusion occurs within the path to the distal end of the cannula. 
     The path may comprise a conduit that conducts the liquid medicament to the cannula. The lock-out may include a pressure detector that detects back pressure within the conduit when an occlusion occurs within the conduit. The conduit may extend from the pump to the distal end of the cannula. 
     The pressure detector may comprise a flexible diaphragm that deflects responsive to back pressure within the conduit. The device may further comprise a linkage that actuates the pump. The lock-out may disable the linkage when an occlusion occurs within the path to the distal end of the cannula. The device may further comprise a deflectable stop that is deflected into the linkage by the diaphragm when an occlusion occurs within the conduit to the distal end of the cannula. The deflector stop and/or the linkage may be permanently deformable or breakable to permanently lock the device and prevent further device actuation. 
     In another embodiment, a disposable wearable infusion device comprises a reservoir that holds a liquid medicament, a cannula having a distal end that delivers the liquid medicament to a patient, a pump that displaces a volume of the liquid medicament from the reservoir to the distal end of the cannula when actuated, a conduit that conducts the displaced liquid medicament to the cannula, and a lock-out including a liquid medicament pressure detector that precludes actuation of the pump when an occlusion occurs within the conduit to the distal end of the cannula. 
     In another embodiment, a disposable wearable infusion device comprises a reservoir that holds a liquid medicament, a cannula having a distal end that delivers the liquid medicament to a patient, a pump that displaces a volume of the liquid medicament from the reservoir to the outlet port when actuated, a conduit that extends from the pump to the cannula to conduct the displaced liquid medicament to the distal end of the cannula, a linkage that actuates the pump, and a lock-out including a liquid medicament pressure detector that disables the linkage to preclude actuation of the pump when an occlusion occurs within the conduit to the distal end of the cannula. 
     The pressure detector may comprise a flexible diaphragm that deflects responsive to back pressure within the conduit, wherein deflection of the flexible diaphragm disables the linkage when an occlusion occurs within the conduit to the distal end of the cannula. The device may further comprise a deflectable stop that is deflected into the linkage by the diaphragm when an occlusion occurs within the conduit to the distal end of the conduit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein: 
         FIG. 1  is a perspective view of an infusion device embodying the present invention shown without a deployed cannula; 
         FIG. 2  is another perspective view of the infusion device of  FIG. 1  shown with a deployed cannula; 
         FIG. 3  is an exploded perspective view of the device of  FIG. 1 ; 
         FIG. 4  is a sectional view, in perspective, to an enlarged scale, taken along lines  4 - 4  of  FIG. 1 , showing the actuation linkages of the device of  FIG. 1  prior to medicament dosage delivery; 
         FIG. 5  is another sectional view, in perspective, to an enlarged scale, taken along lines  5 - 5  of  FIG. 2 , showing the actuation linkage operation of the device of  FIG. 1  during medicament dosage delivery; 
         FIG. 6  is another sectional view similar to that of  FIG. 5 , in perspective, to an enlarged scale, showing the actuation linkage operation of the device of  FIG. 1  immediately after dosage delivery; 
         FIG. 7  is a schematic representation of the valves and pump of the device of  FIG. 1  between medicament dosage deliveries and during the filling of the pump with the medicament; 
         FIG. 8  is another schematic representation of the valves and pump of the device of  FIG. 1  during medicament dosage delivery; 
         FIG. 9  is a sectional view, in perspective, to an enlarged scale, showing the configuration of the valves of the device of  FIG. 1  during pump filling and prior to medicament dosage delivery; 
         FIG. 10  is another sectional view, in perspective, to an enlarged scale, showing the configuration of the valves of the device of  FIG. 1  during dosage delivery; 
         FIG. 11  is a top perspective view of the base of the device of  FIG. 1  illustrating various fluid paths within the device; 
         FIG. 12  is a partial bottom plan view of the base of the device of  FIG. 1  to illustrate the interior of a prime indicator according to one embodiment thereof; 
         FIG. 13  is a bottom plan view of the base of the device of  FIG. 1  illustrating the prime indicator interior covered by a translucent cover according to the above mentioned prime indicator embodiment; 
         FIG. 13A  is a bottom view of the device  110  illustrating a removable non-adhesive layer overlying an adhesive layer on the device base; 
         FIG. 14  is a sectional view in perspective of an occlusion detector and lock-out according to an embodiment of the device of  FIG. 1  shown prior to an intended dosage delivery; 
         FIG. 15  is another sectional view in perspective of the occlusion detector and lock-out shown during an intended dosage delivery; 
         FIG. 16  is another sectional view in perspective of the occlusion detector and lock-out shown during occlusion detection and just prior to lock-out; 
         FIG. 17  is a perspective view of the device of  FIG. 1  and a cannula placement assembly attached thereto ready to provide the device with a cannula according to a still another embodiment; 
         FIG. 18  is a sectional view, in perspective, to an enlarged scale, of the device and cannula placement assembly before the cannula is deployed; 
         FIG. 19  is a sectional view like that of  FIG. 18 , showing the device and cannula placement assembly during cannula deployment; 
         FIG. 20  is a sectional view like that of  FIG. 18 , showing the device and cannula placement assembly after cannula deployment; 
         FIG. 21  is a sectional view, in perspective, of the cannula placement assembly of  FIG. 17 , showing the driver prior to cannula deployment; 
         FIG. 22  is a sectional view, in perspective, and to an enlarged scale, of the cannula placement assembly of  FIG. 17 , showing the driver through a plane perpendicular to the sectional plane of  FIG. 21  and prior to cannula deployment; 
         FIG. 23  is another sectional view similar to  FIG. 22  showing the cannula placement assembly in an enabled configuration; 
         FIG. 24  is a sectional view, in perspective, and to an enlarged scale, showing the cannula placement assembly being released for deploying a cannula; 
         FIG. 25  is a sectional view, similar to that of  FIG. 21 , showing the cannula placement assembly during cannula deployment; 
         FIG. 26  is another sectional view, similar to that of  FIG. 21 , showing the cannula placement assembly after cannula deployment; 
         FIG. 27  is a perspective view of the device and cannula placement assembly after cannula deployment and separation of the cannula driver from the device; 
         FIG. 28  is another sectional view of the cannula placement assembly and device to an enlarged scale showing the device and driver including details of a cannula needle port cover during cannula delivery; 
         FIG. 29  is a sectional view similar to that of  FIG. 28  showing the device and the cannula placement assembly including further details of the cannula needle port cover after cannula deployment; 
         FIG. 30  is a sectional view, to an enlarged scale, showing a drive needle assembly including a drive needle and drive needle head according to a further embodiment of the invention; and 
         FIG. 31  is a sectional view, to an enlarged scale, illustrating an alternative embodiment of a cannula port cover after cannula deployment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1 and 2 , they are perspective views of an infusion device  110  embodying various aspects of the present invention.  FIG. 1  shows the device prior to receiving and thus without a cannula while  FIG. 2  illustrates the device after having received a cannula  130  that has a distal end  131 . As may be seen in both  FIGS. 1 and 2 , the device  110  generally includes an enclosure  112 , a base  114 , a first actuator control button  116 , and a second actuator control button  118 . 
     The enclosure  112 , as will be seen subsequently, is formed by virtue of multiple device layers being brought together. Each layer defines various components of the device such as, for example, a reservoir, fluid conduits, pump chambers, and valve chambers, for example. This form of device construction results in a compact design and enables manufacturing economy to an extent that the device is disposable after use. 
     The base  114  preferably includes a pad  115  attached to the base  114 . The pad  115  has an adhesive coating  117  on the side thereof opposite the base  114  to permit the device to be adhered to a patient&#39;s skin. The adhesive coating may originally be covered with a releasable cover  292  ( FIG. 13A ) that may be pealed off of the adhesive layer  117  when the patient endeavors to adhere the device  110  to their skin. 
     The device  110 , as will be seen herein after is first adhered to the patient&#39;s skin followed by the deployment of the cannula  130  thereafter. However, it is contemplated herein that various aspects of the present invention may be realized within a device that may alternatively be mated with a previously deployed cannula assembly. 
     The actuator buttons  116  and  118  are placed on opposites sides of the device  110  and directly across from each other. This renders more convenient the concurrent depression of the buttons when the patient wishes to receive a dose of the liquid medicament contained within the device  110 . This arrangement also imposes substantially equal and opposite forces on the device during dosage delivery to prevent the device from being displaced and possibly stripped from the patient. As will be further seen hereinafter, the concurrent depression of the buttons is used to particular advantage. More specifically, the actuator button  116  may serve as a valve control which, when in a first position as shown, establishes a first fluid path between the device reservoir and the device pump to support pump filling, and then, when in a second or depressed position, establishes a second fluid path between the device pump and the device outlet or distal end of the cannula to permit dosage delivery to the patient. As will be further seen, a linkage between the control actuator buttons  116  and  118  permits actuation of the device pump with the actuator control button  118  only when the second fluid path has been established by the first actuator control button  116 . Hence, the first actuator control button  116  may be considered a safety control. 
     The actuator buttons  116  and  118  are preferably arranged to require a complete through of their travel to achieve activation of the device pump and thus dosage delivery. This, together with the sudden release of resistance to actuator advancement creates a snap action that provides an advantage in positively knowing that dosage delivery has occurred and that no less than a full dose has been delivered. For more description regarding this feature, reference may be had to co-pending application Ser. No. 11/906,102, titled DISPOSABLE INFUSION DEVICE WITH SNAP ACTION ACTUATION, which application is owned by the assignee of this application and is incorporated herein by reference in its entirety. 
     As may be noted in  FIG. 1 , the device  110  includes a cavity  120  that is arranged to receive a cannula assembly  122  ( FIG. 2 ) from which the cannula  130  extends. When the cannula is deployed, the outlet  124  of the device  110  is placed in fluid communication with the cannula  130  by a cannula carrier  128  of the cannula assembly  122  that carries the cannula. When thus deployed, the cannula  130  extends from the base  114  of the device  110  to beneath the skin of the user. 
     As may further be noted in  FIGS. 1 and 2 , the enclosure  112  of the device  110  includes a pair of pockets  140  and  142  on opposite sides of the second actuator button  118 . A similar pair of pockets, not seen in the figure, are also provided on opposite sides of the first actuator button  116 . These pockets are used to receive corresponding projections of a cannula placement assembly for releasably joining the cannula placement assembly to the device  110  to support cannula deployment as will be described subsequently. As will also be seen, upon cannula deployment, the cannula placement assembly is automatically released from the device by the driver projections being forced from the pockets. 
     Referring now to  FIG. 3 , it is an exploded perspective view of the device  110  of  FIG. 1 . It shows the various component parts of the device The main component parts include the aforementioned device layers including the base layer  160 , a reservoir membrane  162 , an intermediate layer  164  and a top body layer  166 . As may also be seen in  FIG. 3 , the base layer  160  is a substantially rigid unitary structure that defines a first reservoir portion  168 , a pump chamber  170 , and a valve chamber  190  that receives a shuttle bar  200  of a shuttle valve  210 . A reservoir membrane layer  162  is received over the reservoir portion  168  to form an expandable/deflatable reservoir of the device  110  The base layer  160  may be formed of plastic, for example. The base and the top body layer may be joined together, trapping the intermediate layer there between by any means such as with screws, ultrasonic welding or laser welding. 
     The valve chamber  190  is arranged to receive a valve shuttle bar  200  carried by and extending from the first actuator button  116 . A series of O-rings, to be described subsequently, are seated on the shuttle bar  200  to form first, second, and third valves. The actuator button  116  also carries a first linkage portion  240  of the linkage that permits actuation of the device pump with the actuator control button  118  only when the second fluid path has been established by the first actuator control button  116 . The first linkage portion  240  is received within a suitably configured bore  270  formed in the base layer  160  and will be described subsequently. 
     The pump actuator button  118  is arranged to be linked to a pump piston  300  and a second linkage portion  340  to interact with the first linkage portion  240 . The pump piston  300  is arranged to be received within the pump chamber  170  and the second linkage portion  340  is arranged to be received within the bore  270  for interacting with the first linkage portion  240 . O-rings are seated on the piston  300  to provide a seal against leakage and to prevent external contaminants from entering the piston chamber. 
     The intermediate layer  164  may be a generally resilient member and received on the base layer  160  to cover channels scribed in the base layer as a type of gasket to form fluid channels  380  that serve to conduct the medicament from the reservoir to the device outlet and to the distal end  131  ( FIG. 2 ) of the cannula  130 . Springs  410  are arranged to spring load the actuator buttons  116  and  118  away from each other. 
     The reservoir membrane  162  is formed of flexible membrane material and is received over the reservoir portion  168  to form the reservoir of the device  110 . A rigid plate  420  is arranged to be adhered to the reservoir membrane  162  of the reservoir. Because the membrane  162  is flexible, it will move as the reservoir is filled and emptied. The rigid plate  420  will then move with it. The plate  420  includes an eyelet  422  dimensioned to receive an elongated web  424  that forms a part of a medicament level indicator. The web  424  carries an indicator line or feature  426  that may be read through a window  428  of the device top most panel  440 . 
     Another component of the device  110  is a translucent window  450  that is received on the underside of the base  160 . As will be seen hereinafter, the window forms a part of a prime indicator. It is formed of a transparent material such as glass or transparent plastic and has a roughened surface rendering it translucent. However, when it is covered with or at least wetted by liquid medicament, it is rendered essentially transparent creating a visually obvious condition and, for example, permitting indicia to be seen beneath it indicating that the conduit to the device outlet is primed and ready to deliver fixed doses of medicament when desired. 
       FIGS. 4-6  show details of the operation of the linkage that permits actuation of the device pump with the actuator control button  118  only when the second fluid path from the reservoir to the outlet has been established by the first actuator control button  116 . The linkage has been given the general reference character  150 . 
     As may be seen  FIG. 4 , the first actuator button  116  has an extension  152  that terminates in a block  154 . The block  154  has a first ramp surface  156  and a second ramp surface  158 . When the device  110  is actuated, the button  116  is concurrently depressed with pump button  118 . It and its extension  152  and block  154  are free to move to the right. As seen in  FIGS. 4 and 5 , the pump actuator button  118  has parallel extensions  250  and  252  which are joined and separated be a rod member  254 . The extensions  250  and  252  are pivotally mounted to pivot about a pivot point  256 . Another extension  260  of the pump actuator button  118  spring biases the extensions  250  and  252  as shown in  FIG. 4 . As seen in  FIG. 4 , the extensions  250  and  252  abut an abutment  262  which they must clear to enable the actuator  118  to be moved to the left. As shown in  FIG. 5 , as the button  116  is depressed, its extension  152  moves to the right causing the first ramp surface  156  to engage the rod member  254 . Continued movement of the button causes the rod member  254  to ride up the first ramp surface  156  which in turn causes the extensions  250  and  252  to begin to move slightly to the left and bend upward against the loading of extension  260 . Eventually, the rod member  254  rides up the length of the first ramp  156  and down the second ramp  158  causing the extensions  250  and  252  to clear the abutment  262  and continue their travel to the left until the extensions are received on the opposite side of the abutment as shown in  FIG. 6 . The pump button  116  has now been fully depressed to deliver a dose of measured medicament. When the ends of extensions  250  and  252  totally clear the abutment  262 , they will snap behind the abutment  262  as shown in  FIG. 6  and become temporarily locked. Meanwhile, the rod member  254  has traversed all the way down the second ramp surface  158 . The buttons  116  and  118  are now fully depressed. 
     Hence, from the above, it may be seen that the pump button  118  could not at first move freely while the first actuator button  116  which operates the valves could. As a result, the pump actuation lags behind the valve actuation. This enables the device outlet to be sealed from the reservoir and the pump connected to the outlet before the pump is permitted to pump any medicament to the outlet. Hence, the device establishes a medicament delivery flow path to the cannula before the pump is able to begin pumping the medicament to the patient. Thus, it is assured that there is never an open unobstructed pathway between the reservoir and the fluid outlet. Also, by assuring that the pump only draws fluid from the reservoir when the pathway to the outlet is sealed off, it is also assured that a precise amount of fluid is moved with each pump cycle. This operation is completely timed by the linkage just described and occurs quickly, appearing to the patient that both actuator buttons are moving at the same rate. 
     When the extensions  250  and  252  of the pump button clear the abutment  262 , they become locked in a snap action. This provides positive feedback to the patient that a dosage of medicament was delivered as desired. It also causes a full dose to be delivered. By virtue of the snap action of the pump actuator, only full doses may be administered. 
     When the medicament has been delivered, the spring loading of the actuator buttons returns the buttons to their first or initial position. During this time, the same timing provided by the block  154  is used for recharging the pump. More specifically, ramp  158  unlatches the ends of extensions  250  and  252  by lifting rod member  254 . While the extensions  250  and  252  are being lifted by the ramp  158 , the valve control button  116  is returning to the left to cause the outlet to be disconnected from the pump before the reservoir is reconnected to the pump for charging, thus sealing the outlet from both the pump and the reservoir before the reservoir is connected to the pump for recharging. This assures that the pump does not pull medicament from the patient but only from the reservoir. As the pump returns, a full dose of the medicament is drawn up into the piston chamber  170  to ready the device for the next dosage delivery. 
     Referring now to  FIGS. 7 and 8 , they are schematic representations of the valves and pump of the device of  FIG. 1  between medicament dosage filling ( FIG. 7 ) and medicament dosage delivery ( FIG. 8 ) As may be seen in  FIGS. 7 and 8 , the device  110  further includes a reservoir  222 , a pump  224 , and the cannula  130 . The reservoir  222  may be formed as shown in  FIG. 3  by the combination of the device base  160  and the flexible membrane  162 . The device further includes the shuttle valve  210  including shuttle bar  200 . The shuttle bar  200  is shown within the valve chamber  190 . The shuttle bar  200  and O-rings  214  and  216  form a first valve  212 , shuttle bar  200  and O-rings  220  and  222  form a second valve  234  and shuttle bar  200 , O-ring  226  and a bypass channel  186  form a third valve  224 . Although O-rings are used herein to form seals, other types of valve construction may employ forms of seals other than O-rings without departing from the invention. 
     The pump piston  300  is within the piston camber  170  to form a piston pump  172 . The actuator control button  218  is directly coupled to and is an extension of the pump piston  226 . It may also be noted that the actuator buttons  116  and  118  are spring loaded by springs  117  and  119 , respectively. The springs are provided for returning the actuator buttons to a first or start position after a dosage is administered. 
     A fluid conduit  182  extends between the reservoir  180  and the valve  212 . An annular conduit  192  extends between the O-rings  216  and  226 , and an annular conduit  194  extends between the O-rings  226  and  220 . A fluid conduit  184  provides a fluid connection between the reservoir  180  and the annular conduits  192  and  194  depending upon the position of the shuttle valve  210 . Also illustrated in  FIG. 7  is the linkage  150  that assures that the shuttle valve  210  is actuated before the piston pump  172  is actuated to provide a dose of medicament. 
     In  FIG. 7 , the valves are shown in a first configuration immediately after having returned to their first position following a dosage delivery. After the return of the valves, the linkage  150  permits the pump actuator  118  and piston  300  to return for refilling the pump chamber  300  in ready for the next medicament dosage delivery. During their return, the medicament flows as indicated by arrows  202  from the reservoir  180 , through the conduit  182 , through the annular channel  192 , through conduit  184 , and into the pump chamber  170 . 
     As may be noted, when in the first position, the valves  218  and  224  isolate the outlet  124  from both the reservoir  180  and the piston pump  118 . Having two such valves isolate the outlet  124  when the valves are in the first configuration provides an added degree of safety from medicament being inadvertently delivered to the patient between dosage deliveries. For example, this provides additional safety that the liquid medicament is not accidentally administered to the patient notwithstanding the inadvertent application of pressure to the reservoir. In applications such as this, it is not uncommon for the reservoir to be formed of flexible material. While this has its advantages, it does present the risk that the reservoir may be accidentally squeezed as it is worn. Because the valves  118  and  124  isolate the outlet  124  when the valves are in their first configuration, this redundant protection assures that pressure, accidentally applied to the reservoir, will not cause the fluid medicament to flow to the cannula. 
     In addition to the linkage  150  preventing return of the piston  300  until after the valves return to their first and start positions, the O-rings on the shuttle bar  200  are also spaced apart to insure that the valves  218  and  224  isolate the outlet  124  from the pump  172  and reservoir  180  before the pump is again connected to the reservoir. The O-ring spacing thus effectively forms a second linkage to assure that the cannula  130  is connected to the pump  172  only when a dosage is to be delivered and that it is never connected to the reservoir  180 . 
     In operation, the pump chamber  170  is first filled as the actuator button  118  returns to the first position after having just delivered a medicament dosage. In this state, the shuttle valve  210  is set so that the first valve  212  will be open and the second and third valves  218  and  224  will be closed. This establishes a first fluid path indicated by arrows  202  from the reservoir  180  to the pump chamber  170  to fill the piston pump  172 . When the patient wishes to receive another dose of medicament, the actuator buttons are concurrently pressed. The aforementioned linkages, including linkage  150 , cause the first valve  212  to close and the second and third valves  218  and  224  to thereafter open. Meanwhile, actuation of the pump  172  is precluded until the first valve  212  is closed and the second and third valves  118  and  224  are opened. At this point a second fluid path indicated by arrows  204  is established from the pump chamber  170  to the cannula  130 . The medicament is then administered to the patient through the distal end  131  of cannula  130 . 
     Once the medication dosage is administered, the piston  330 , and thus the actuator button  118 , is returned under the spring pressure of spring  119  to its initial position. During the travel of the piston back to its first position, a given volume of the liquid medicament for the next dosage delivery is drawn from the reservoir into the pump chamber  170  as described above to ready the device for its next dosage delivery. 
     Referring now to  FIG. 9 , it is a sectional view in perspective showing the valve configuration of the device  110  of  FIG. 1  during medicament filling of the pump chamber  170  immediately after a dosage delivery. Here, it may be clearly seen that the first actuator button  116  is directly coupled to the shuttle bar  200  of the valves  212 ,  218 , and  224 . Above the valves are the conduits from the reservoir, from the pump, and to the cannula. More particularly, the conduit  182  is in fluid communication with the reservoir, the conduit  184  is in fluid communication with the pump, and the conduit  124  is in fluid communication with the cannula. The valves are shown with the first valve  212  opened, communicating reservoir conduit  182  with the pump conduit  184  through channel  192 , the second valve  218  closed and blocking the conduit  124  to the cannula, and the third valve  224  closed and blocking both the reservoir conduit  182  and the pump conduit  184  from the cannula conduit  124 . This permits medicament to flow from the reservoir through conduit  182 , through channel  192 , and to the pump chamber  170  through conduit  184  as the actuator button  116  returns to its first position. Hence, the pump chamber is filled and ready for the next dosage delivery. 
     Referring now to  FIG. 10 , it is a sectional view in perspective similar to that of  FIG. 9  but showing the valve configuration of the device  110  of  FIG. 1  during medicament delivery. Here, the valves are shown with the first valve  212  closed and blocking the reservoir conduit  182 , the second valve  218  opened permitting the outlet conduit  124  to communicate with the annular conduit  194 , and the third valve  224  opened permitting medicament to flow from the annular conduit  192 , through bypass  186 , and to annular conduit  194 . Thus, medicament is permitted to flow from the pump conduit  184 , through annular conduit  192 , through the bypass  186 , through annular conduit  194 , and into the outlet conduit  124  to administer the fixed volume dosage As previously mentioned, the O-rings defining the first valve  212 , the third valve  224 , and the second valve  218  are spaced apart so that conduit  182  is blocked before conduits  184  and  124  are connected together through the valves  224  and  218 . 
       FIG. 11  is a top perspective view of the base  160  of the device  110  of  FIG. 1 . Carried on the base  160  is the intermediate layer  164 . Together, the base  160  and intermediate layer  164  define numerous fluid conduits within the device  110 . One such fluid conduit is designated with reference character  270  in  FIG. 11 . The conduit  270  is within the fluid path that leads to the outlet  124 . It is in the downstream portion of that path and takes a bend at  272  towards the bottom side of the base  160  where it, through an opening  274 , enters a chamber  276  ( FIG. 12 ). The chamber  276  communicates with the device outlet  124  that projects into the aforementioned cavity  120 . When the cannula  130  ( FIG. 13 ) is placed, it extends through an opening  123  in the cavity to beneath the patient&#39;s skin and communicates with the outlet  124  as described herein after. 
     The chamber  276  is partly defined by a seal rim  278  which receives a translucent cover  280  ( FIG. 13 ). The top wall of the chamber  276  has an inverted cone shaped surface  282  portion and a tapered portion  284  to the outlet  124 . 
     The translucent cover may be formed of transparent plastic wherein the surface that faces the chamber is roughed in a manner that renders the plastic cover translucent. The upper surface of the chamber is preferably coated with indicia which may, for example, be a color, such as blue. When the chamber is empty, the blue indicia will not be readily seen because the rough surface of the cover has rendered the cover translucent. However, when the chamber  276  is filled with a liquid, such as the liquid medicament, the cover  280  will become more transparent allowing the blue indicia to be readily seen. The chamber  276  and cover  280  thus form a prime indicator  286  adjacent the outlet  124 . More particularly, the prime indicator  286  is immediately adjacent the outlet  124  since when the chamber is filled and the indicia readily seen, it will be known that the conduits and cannula are sufficiently prime with medicament to permit a full dosage to be delivered upon the next activation of the device  110 . 
     In use, it is contemplated that the reservoir be filled through a fill port  290  on the bottom of the device  110  before the device is deployed on the patient&#39;s skin. After the device is filled, the translucent cover or window  280  may be viewed during device priming. During the priming process, the actuators  116  and  118  may be depressed a number of times until the blue indicia on the top surface portions  282  and  284  of the chamber are seen through the window  280 . This provides an indication to the user that the chamber  276 , and more importantly, the conduits are sufficiently primed and full with medicament to enable actual dosage delivery upon the next actuation of the device  110 . Hence, a prime indicator  286  is provided immediately adjacent the outlet  124 . 
     In  FIG. 13A , it may be seen that the removable non-adhesive layer  292 , in accordance with this embodiment, includes two portions, a first portion  293  and a second portion  294 . Each of the first and second layer portions  293  and  294 , respectively, includes a tab  298  and  297  respectively that extend beyond the margins of the device base. This permits the tabs  297  and  298  to be grasped for effortless removal of the removable non adhesive layer portion  294  and  293 . The layer portion  293  includes cutouts. The cutouts  295  and  296  extend through the pad  115  ( FIG. 2 ) to provide access to the device fill port  290  and the prime indicator window  280 . Hence, as described above, the device  110  may be filled and primed for use before the removable layer portions  293  and  294  are removed for adhering the device to a patient&#39;s skin. 
       FIGS. 14-16  are sectional views in perspective of an occlusion detector and lock-out  350  according to an embodiment of the device of  FIG. 1 .  FIG. 14  shows the occlusion detector and lock-out  350  prior to an intended dosage delivery,  FIG. 15  shows the occlusion detector and lock-out  350  during to an intended dosage delivery, and  FIG. 16  shows the occlusion detector and lock-out  350  during occlusion detection and just prior to lock-out. 
     The occlusion detector and lock-out  350  serves to detect, during each dosage delivery, blockages between the shuttle valve and the distal end  131  of the cannula  130  ( FIG. 8 ). Such blockages are most likely to occur within the cannula and may result in an improper amount of medicament being delivered during an attempted dosage delivery. For example, the user might have an erroneous belief that a full dosage had been delivered when, in fact, a dosage of insufficient quantity had been delivered. As will be seen subsequently, the occlusion detector is responsive to pressure within the pathway from the shuttle valve to the outlet and cannula that occurs during an attempted dosage delivery when a blockage exists. 
     The occlusion detector  350  has an inlet  132  that communicates with the outlet  124  ( FIG. 10 ) of the shuttle valve  210  and an outlet  134  that communicates with the prime indicator  286  ( FIG. 12 ). Between the inlet  132  and the outlet  134  is a channel  136 . Hence, the channel  136  is within the fluid path from the valve to the outlet  125  of the device that may be coupled to the cannula  130  ( FIGS. 7 and 8 ). The occlusion detector  350  also includes a resilient diaphragm  352  over which the channel  136  extends Adjacent the diaphragm  352  is a deflectable stop  354  As will be seen subsequently, when there is an occlusion within the fluid path, an attempted dosage delivery results in an increased back pressure against the diaphragm  352  and the deflectable stop  354 . This causes the deflectable stop  354  to engage a projection  157  of the linkage  150 . This disables the linkage  150  that controls the interaction of the actuator buttons  116  and  118  and that causes the actuator buttons  116  and  118  to become locked. 
     More particularly, as may be further seen in  FIG. 14 , the linkage  150  is adjacent the occlusion detector  350 . When the actuator buttons are depressed, the projection  157 , carried by the extension  152  of the valve actuator button  116 , slides across block  255  carried on pivot  256 . 
     As may be seen in  FIG. 15 , upon further depression of buttons  116  and  118 , the projection  157  slides past the distal end of the deflectable stop  354 . It may also be seen that, as previously described, the rod member  254  has ridden up the first ramp  156  and down the second ramp  158  of block  154 . This causes the first ramp  156  to engage a ramp surface  257  of block  255 . 
     If no occlusion exists within the fluid path to the cannula, the blocks  154  and  255  and the actuator buttons  116  and  118  will return as previously described under spring pressure. However, if an occlusion does exist within the fluid path to the cannula, back pressure will quickly build in the channel  136  to cause the deflectable stop  354  to be deflected downwardly. This is shown in  FIG. 16 . The deflectable stop  354  is now aligned with the projection  157 . When, under spring pressure, the actuator buttons  116  and  118  are urged to their starting positions, the projection  157  will be caught by the deflectable stop  354  to lock the device and preclude its further use. Still further, the deflectable stop  354  or the projection  157  may be breakable or permanently deformable upon their engagement. This would render the linkage  150  jammed and irreversibly locked to permanently preclude further use of the device. 
     Referring now to  FIG. 17 , it is a perspective view of the device  110  of  FIG. 1  with a cannula placement assembly  500  releasably attached thereto ready to provide the device with a cannula according to a still another embodiment. It is contemplated that the device  110  and cannula placement assembly  500  be pre-attached to each other upon delivery to a patient and that upon placement of the cannula, the cannula placement assembly  500  be automatically separated from the device  110 . 
     The cannula placement assembly  500  generally includes a cannula driver portion  510  and an actuation portion  512 . The cannula driver portion  510  is generally cylindrical in shape including a drive cylinder  514 . The actuation portion includes an actuator button  516  and a safety control button  518 . As will be seen subsequently, the safety control button  518  must first be depressed into a locked depressed position before the actuator button  516  may be depressed to set the cannula placement sequence into motion. 
       FIG. 18  is a sectional view, in perspective, to an enlarged scale, of the device  110  and cannula placement assembly  500  before the cannula is deployed. As may be noted in  FIG. 18 , the interior components of the cannula driver portion  510  includes a plunger  524 , a needle assembly  520 , and the cannula assembly  122 . 
     The cannula assembly, as previously described, includes the cannula  130 , of the type known in the art, and a cannula carrier  128 . The cannula carrier  128  is arranged to be received within the cavity  120  into which the device outlet  124  projects. Once the cannula carrier  128  is received into the cavity  120 , the cannula carrier  128  establishes a fluid path from the outlet  124  to the cannula  130 . 
     The needle assembly  520  includes a drive needle  522 . The drive needle  522  includes a needle head assembly  526  and a needle shaft  527 . Before the cannula  130  is placed, the cannula assembly  122  is carried by the needle assembly  520  and more specifically, by the cannula  130  being received on the drive needle  522  with the cannula carrier  128  being immediately adjacent the drive plunger  524  as shown. 
     The needle head assembly  526  is initially seated within the drive plunger  524 . To that end, the needle head assembly  526  is within the plunger  524  and has an exterior surface  530  that conforms to the interior surface  532  of a wall portion  531  of the plunger  524 . The needle shaft  527  extends from the needle head assembly  526 , through an opening of the plunger  524 , through the cannula carrier  128 , and finally through the cannula  130  to terminate at a tip  521 . During cannula placement, the cannula  130  and drive needle  522  extend through the opening  123  of the device  110 . 
     The cannula driver  510  further includes a first drive spring  534  and a second drive spring  536 . The first drive spring is originally compressed between an inner end wall  538  of the drive cylinder  514  and a top surface  540  of the plunger  524 . The first drive spring  534  serves to drive the plunger  524  downwardly to in turn drive the cannula  130  and the drive needle  522  through the opening  123 . 
     The plunger  524  is released by the actuator button  516  being depressed. As will be seen subsequently, the actuator button  516  includes a portion that interferes with a shoulder of the plunger  524 . When the actuator button is depressed, that interference is resolved and the drive carrier  524  is free to move downwardly under the influence of the first drive spring  534 . The needle tip  521  pierces the patient&#39;s skin and the lower portion of the needle shaft  527  and cannula  130  are placed beneath the patient&#39;s skin. The cannula  130  and needle  522  quickly reach the fully driven, temporary, configuration shown in  FIG. 19 . 
     In  FIG. 19 , it may be seen that the cannula  130  and needle shaft  527  upon which the cannula  130  is carried have been driven through the opening  123  of the device  110 . The first drive spring  534  is now in an extended condition. 
     When the cannula driver  510  reaches the configuration shown in  FIG. 19 , the wall portion  531  of the plunger  524  clears a shoulder  542  of a short wall portion  544  of the drive cylinder  514 . The wall portion  531  springs outwardly separating the conformal surfaces  530  and  532  of the wall portion  531  and the needle head  526 , respectively. This frees the needle head  526  from the plunger  524 . The needle head  526  is now free to move upwardly out of and away from the plunger  524  under the influence of the second drive spring  536 . 
     As the needle head  526  moves upwardly, it of course takes the needle shaft  527  with it. When the needle head  526  reaches the extent of its travel ( FIG. 20 ) by the extension of the second drive spring  536  (the first drive spring  534  has been omitted from the figure for clarity), the needle shaft  527  is fully extracted from the cannula  130  leaving only the cannula  130  beneath the patient&#39;s skin. The cannula carrier  128  has also been received within the cavity  120  of the device  110 . As the cannula carrier  128  is received within the cavity  120 , the device outlet  124  is placed into fluid communication with the cannula  130  through the cannula carrier  128 . 
       FIG. 21  is a sectional view, in perspective, showing details of the actuator portion  512  of the cannula placement assembly  500  of  FIG. 17 , as configured prior to cannula deployment. As previously described, the actuator portion  512  includes the safety control button  518  and the actuator  516 . 
     The safety control button includes a recess  550  and the actuator button  516  includes an extension  560 . Before actuation, the extension  560  of the actuator  516  abuts the safety control button to preclude the depressing of the actuator  516 . However, when the safety control button is depressed, as will be seen subsequently, the recess  550  is brought into alignment with the extension  560  to permit the actuator  516  to be depressed for setting into motion the placement of the cannula  130  as previously described. 
     As may also be noted in  FIG. 21 , the cannula placement assembly  500  further includes a plurality of projections  562  and  564 . It is also contemplated that the cannula placement assembly  500  includes two additional such projections. The projections are arranged to be received within corresponding pockets of the wearable infusion device to permit the cannula placement assembly  500  to be releasably carried on the device  110  as shown, for example, in  FIG. 17 . For example, projection  562  is intended to be received by pocket  140  of the device  110  of  FIGS. 1 and 2 . The distance between the projections  562  and  564  is maintained by a latch  566  that includes a bendable arm  568  and a catch  572 . The bendable arm includes a hook  570  at its distal end that is held by the catch  572 . At least one urging member in the form of springs  573  and  575  ( FIG. 20 ) serve to provide a continuous force for separating the projections  562  and  564 . That force also maintains the hook  570  locked onto the catch  572 , and the hook  570  being locked onto the catch  572  maintains the projections within their respective pockets to releasably maintain the cannula placement assembly  500  on the device  110 . 
     The actuator  516  still further includes a latch release projection  580 . The latch release projection  580  includes a ramped surface  582  arranged to engage and bend the bendable arm  568  as the actuator  516  is depressed. Eventually, sufficient depression of the actuator  516  bends the arm  568  sufficiently to cause the hook  570  to clear the catch  572 . The actuator is shaped in such a manner that, as it is depressed in a single motion, it causes release and placement of the cannula before the hook  570  clears the catch  572 . When the hook  570  clears the catch  572 , the latch  566  is released and the projections, including projections  562  and  564  are forced apart under spring pressure to cause the cannula placement assembly  500  to be separated from the device  110 . 
       FIG. 22  is a sectional view, in perspective, and to an enlarged scale, of the cannula placement assembly of  FIG. 17 , showing the assembly through a plane perpendicular to the sectional plane of  FIG. 21  and prior to cannula deployment. Here it may be seen that the control button  518  includes a pair of chordal recesses  580  and  582  that defined bendable legs  584  and  586  respectively. Each of the legs  584  and  586  includes a projecting foot  588  and  590  respectively. When the safety control button  518  is in a raised initial position as shown in  FIG. 22 , the foot  588  is confined within a slot  592  of an extension  598  of the actuator button  516  and the foot  590  is confined within a slot  594  of another extension  598  of the actuator button  516 . 
     When the control button  518  is depressed, the legs  580  and  586  permit the feet  588  and  590  to slide out of their respective slots  592  and  594 , respectively. They then progress downwardly until the legs  584  and  586  and feet  588  and  590  wrap about the extensions  596  and  598  of the actuator  516 . The feet  588  and  590  become confined beneath bottom surfaces  600  and  602 , respectively, of the actuator button extensions  596  and  598 , respectively to lock the safety control  518  in the enable configuration of  FIG. 23 . 
     In  FIG. 23  it may be clearly seen that the feet  588  and  590  are beneath and confined by the bottom surfaces  600  and  602 , respectfully, of the actuator button extensions  596  and  598 . The bendable legs  584  and  586  cause the control button  516  to enter this configuration with a snap action. This provides positive feedback to the user that the control button has been successfully depressed and that the cannula placement assembly is now ready for the depression of the actuator button  516 . The confinement by the actuator extensions  596  and  598  of the feet  588  and  590  causes the control button  518  to be locked in the depressed enable state. This conveys to a user after use that the cannula placement assembly is not to be reused and even assists in making such reuse impossible or at least difficult. 
     With the control button now depressed and engaged in the enable configuration, the extension  560  of the actuator button  516  ( FIG. 21 ) will now be aligned with the slot  550  of the control button  518 . This permits the actuator to be depressed and actuated. 
       FIGS. 24 and 25  are sectional views showing the cannula placement assembly  500  as the actuator button  516  is being depressed. In  FIG. 25  it may be seen that the extension  560  of the actuator button  516  is aligned with and entering into the slot  550  of the control button  518 . As this occurs, the extension  598  slides in the chordal recess  582  of the control button  518  and the extension  596  slides in the chordal recess  580  of the control button. 
     The extension  598  further includes a wing  610  having an upper surface  612  that normally engages a lower surface  523  of the plunger  524  to interfere with the movement of the plunger  524  as previously described. As the actuator button  516  is depressed, the upper surface  612  of the extension  598  clears the lower surface  523  of the plunger  524 . When this occurs, the drive carrier is released to be driven by spring  534  for placing the cannula  130  into a deployed position beneath the patient&#39;s skin. 
       FIG. 25  further shows that the latch  566  includes a second catch  573 . The second catch  573  serves to catch the hook after it is lifted over the first catch  772 . The second catch  573  is also positioned so that even though it catches the hook  570 , the projections are still separated sufficiently to release the cannula placement assembly  500  from the device  110 . The cannula placement assembly will not fall apart because it is held together in part by the second catch  572  catching the hook  570 . 
       FIG. 26  is a sectional view showing the cannula placement assembly  500  after cannula deployment. The assembly is separated from the device. The projection  560  is fully within the slot  550  of the control button  518 . This serves to further preclude reuse of the assembly  500  after cannula placement 
       FIG. 27  is a perspective view of the device  110  and cannula placement assembly  500  after cannula deployment and separation of the cannula placement assembly from the device. Clearly seen in  FIG. 27  are the remaining projections  563  and  565  and remaining pockets  141  and  143  for releasably retaining the assembly  500  on the device  110 . After cannula placements the separated cannula placement assembly  500  may be disgarded. 
       FIG. 28  is a sectional view of the cannula placement assembly  500  and the device  110  to an enlarged scale showing details of a cannula needle port cover  125  during delivery of the cannula  130 . The cannula  130  is carried on the cannula carrier  128 . The cannula carrier includes a port  127  through which the needle  522  passes when it is retracted back into the driver  510  by the spring  536 . To preclude access into the device and especially direct access to the cannula through the port  127  after the cannula  130  has been deployed, the cannula carrier  128  includes the port cover  125 . In accordance with this embodiment, the port cover is made of relatively impenetrable material such as hard plastic or steel or the like and is substantially U-shaped and is confined within a slot  129 . One leg of the port cover  125  is displaced and held away from the port  127  by the needle  522 . It is a resilient material, such as spring steel and is held in place in, for example, a slightly compressed state, by the needle shaft  527  which is loaded through the hole in the port cover as shown at  125  in  FIG. 28 . Responsive to the cannula  130  being placed and the needle shaft  527  removed from the device  110 , the one leg of the port cover is freed and permitted to spring to its natural shape such that the one leg overlies the port  127  as shown at  125  in  FIG. 29  and in greater detail at  727  in  FIG. 31 . This results in the port  127  being blocked to preclude access to the interior of the device  110  once the cannula has been placed. Once the cannula  130  is deployed, the device  110  will appear as shown in  FIG. 2 . As previously mentioned, when the cannula  130  is placed, a fluid connection is established between the outlet  124  and the cannula  130  through the cannula carrier  128 . After priming, the device  110  is ready to deliver its first dose of medicament. 
       FIG. 30  is a sectional view, to an enlarged scale, showing another driver needle assembly  620  including a drive needle shaft  622  and drive needle head  626  according to a further embodiment of the invention. Here it may be seen that the drive needle shaft  622  and the drive needle head  626  are two separate parts. The drive needle shaft  622  has a turned section  623  and an elongated section  627 . The turned section  623  rides in a slot  630  of the drive needle head  626 . The elongated section  627  passes through and is free to slide on a through bore  628  of the drive needle head  626 . The needle assembly  620  may be used to assist in cannula placement and returned by spring  536  after cannula deployment in the same manner as previously described. 
       FIG. 31  is a sectional view, to an enlarged scale, illustrating an alternative embodiment of a cannula port cover  725 . The port cover is shown covering a needle port  727  after cannula deployment. The port  727 , as in the precious embodiment, is defined by the cannula carrier  728 . The port cover  725  is generally U-shaped and confined in a cut-out  730 . The cut-out  730  has a width that is greater than the diameter of the needle slot  727  to permit a cannula driver needle (not shown) to pass there through upon return after cannula placement The port cover  725  has an end  729  that is confined by the cut-out  730  and a slot  732  formed in a side wall of the cannula carrier  728 . The port cover  725  is therefore free to pivot to the position shown after the cannula driver needle (not shown) passes there through upon its return. 
     As may be noted in  FIG. 31 , the port cover  725  has a width, adjacent the port  727 , that is smaller than the diameter of the port  727 . While the port cover  725  does not completely cover the port  727 , it is still of sufficient dimension to preclude access to the cannula through the port  727  by, for example, an external syringe needle. 
     While particular embodiments of the present invention have been shown and described, modifications may be made. It is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention as defined by those claims.