Abstract:
An apparatus for accurately infusing medicinal agents into an ambulatory patient at specific rates over extended periods of time. The apparatus includes a housing having a delivery outlet and an elastic distendable membrane for defining a chamber within the housing. Also provided is a flow rate control assembly delivery outlet. The apparatus further includes a mechanism for quickly and easily priming the fluid flow passageways of the fluid delivery component. Additionally, the apparatus includes a novel fluid flow indicator that provides a readily discernible visible indication of fluid flow through the apparatus. Further provided is a fill assembly for filling the fluid reservoir of the device with a selected medicinal fluid and locking mechanisms for preventing unauthorized tampering with the flow rate control mechanism as well as the priming mechanism.

Description:
[0001]    This is a Continuation-In-Part of co-pending U.S. application Ser. No. 09/165,706 filed Oct. 2, 1998 which is a Continuation-In-Part of U.S. application Ser. No. 08/768,663 filed Dec. 18, 1996. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to fluid delivery devices. More particularly, the invention concerns an improved apparatus for infusing medicinal agents into an ambulatory patient at specific rates over extended periods of time, which apparatus includes fluid flow indicator means and a novel adjustable flow rate control means for precisely adjustably controlling the rate of fluid flow from the reservoir of the device and means for priming the device to fill the fluid passageways thereof prior to commencing the delivery step.  
           [0004]    2. Discussion of the Prior Art  
           [0005]    Many medicinal agents require an intravenous route for administration thus bypassing the digestive system and precluding degradation by the catalytic enzymes in the digestive tract and the liver. The use of more potent medications at elevated concentrations has also increased the need for accuracy in controlling the delivery of such drugs. The delivery device, while not an active pharmacologic agent, may enhance the activity of the drug by mediating its therapeutic effectiveness. Certain classes of new pharmacologic agents possess a very narrow range of therapeutic effectiveness, for instance, too small a dose results in no effect, while too great a dose results in toxic reaction.  
           [0006]    In the past, prolonged infusion of fluids has generally been accomplished using gravity flow methods, which typically involve the use of intravenous administration sets and the familiar bottle suspended above the patient. Such methods are cumbersome, imprecise and require bed confinement of the patient. Periodic monitoring of the apparatus by the nurse or doctor is required to detect malfunctions of the infusion apparatus. Devices from which liquid is expelled from a relatively thick-walled bladder by internal stresses within the distended bladder are well known in the prior art. Such bladder, or “balloon” type, devices are described in U.S. Pat. No. 3,469,578, issued to Bierman and in U.S. Pat. No. 4,318,400, issued to Perry. The devices of the aforementioned patents also disclose the use of fluid flow restrictors external of the bladder for regulating the rate of fluid flow from the bladder. The prior art bladder type infusion devices are not without drawbacks. Generally, because of the very nature of the bladder or “balloon” configuration, the devices are unwieldy and are difficult and expensive to manufacture and use. Further, the devices are somewhat unreliable and their fluid discharge rates are frequently imprecise.  
           [0007]    The apparatus of the present invention overcomes many of the drawbacks of the prior art by eliminating the bladder and making use of recently developed elastomeric films and similar materials, which, in cooperation with a base define a fluid chamber that contains the fluid which is to be dispensed. The elastomeric film membrane controllably forces fluid within the chamber into fluid flow channels provided in the base.  
           [0008]    The elastomeric film materials used in the apparatus of the present invention, as well as various alternate constructions of the apparatus, are described in detail in U.S. Pat. No. 5,205,820 issued to the present inventor. Therefore, U.S. Pat. No. 5,205,820 is hereby incorporated by reference in its entirety as though fully set forth herein. Co-pending U.S. Ser. No. 08/768,663 filed by the present inventors on Dec. 18, 1996 also describes various alternate constructions and modified physical embodiments of the invention. Because the present application discloses improvements to the apparatus described in U.S. Ser. No. 08/768,663, this co-pending application is also hereby incorporated by reference in its entirety as though fully set forth herein. Similarly, U.S. Ser. No. 09/165,706 filed Oct. 2, 1998 filed by the present inventors describes various alternate embodiments of the invention. U.S. Pat. No. 5,721,382 issued to the present inventor on Feb. 24, 1998 discloses an apparatus for indicating fluid pressure within a conduit. The present invention comprises an improvement to the devices disclosed in this latter patent and, therefore, U.S. Pat. No. 5,721,383 is also incorporated by reference as though fully set forth herein.  
           [0009]    The apparatus of the present invention can be used with minimal professional assistance in an alternate health care environment, such as the home. By way of example, devices of the invention can be comfortably and conveniently removably affixed to the patient&#39;s body and can be used for the continuous infusion of antibiotics, hormones, steroids, blood clotting agents, analgesics, and like medicinal agents. Similarly, the devices can be used for I-V chemotherapy and can accurately deliver fluids to the patient in precisely the correct quantities and at extended microfusion rates over time.  
           [0010]    The embodiments of the inventions described in Ser. No. 08/768,663, and U.S. Ser. No. 09/165,706 which applications are incorporated herein by reference, concern fluid delivery devices having a fluid reservoir and an indicator assembly for indicating fluid flow through the apparatus. U.S. Ser. No. 09/165,706 also discloses a novel adjustable fluid flow rate mechanism. However, the apparatus of the present invention, includes alternate types of adjustable fluid flow rate mechanisms and also includes a novel priming mechanism for priming the device prior to commencing fluid delivery to the patient. As will be better understood from the description which follows, the novel adjustable fluid flow rate control mechanism of the present invention includes a novel type of rate control element that precisely controls the rate of fluid flow to the patient and also includes novel lockout means for disabling the priming mechanism and for locking the fluid flow rate control mechanism in a selected position.  
         SUMMARY OF THE INVENTION  
         [0011]    It is an object of the present invention to provide an apparatus for expelling fluids at a precisely controlled rate which is of a compact, low profile, laminate construction. More particularly, it is an object of the invention to provide such an apparatus which can be used for the precise infusion of pharmaceutical fluids to an ambulatory patient at controlled rates over extended periods of time.  
           [0012]    It is another object of the invention to provide an apparatus of the aforementioned character which is highly reliable and easy-to-use by lay persons in a non-hospital environment.  
           [0013]    Another object of the invention is to provide an apparatus, which can readily be filled in the field shortly prior to use.  
           [0014]    A further object of the invention is to provide a low profile, fluid delivery device of laminate construction which can be manufactured inexpensively in large volume by automated machinery.  
           [0015]    Another object of the invention is to provide a device of the aforementioned character which includes novel adjustable flow rate control means disposed intermediate the fluid reservoir outlet and the outlet port of the device for precisely controlling the rate of fluid flow from the outlet port toward the patient.  
           [0016]    Another object of the invention is to provide a device of the character described which embodies a highly novel fluid flow indicator that provides a readily discernible visual indication of fluid flow status through the device.  
           [0017]    Another object of the invention is to provide an apparatus of the aforementioned character which includes novel priming means for priming the device prior to commencing the fluid delivery step.  
           [0018]    Another object of the invention is to provide unique fill means for use in controllably filling the fluid reservoir of the apparatus.  
           [0019]    Another object of the present invention is to provide an apparatus of the aforementioned character in which the flow rate control means comprises a rotatable support disk that carries a plurality of capillary type rate control elements and is constructed and arranged so that it can be conveniently rotated by the treating physician to selectively position the rate control elements within the fluid flow path that extends between the fluid reservoir and the device outlet port.  
           [0020]    Another object of the present invention is to provide an apparatus that includes novel means for preventing the unauthorized manipulation of the priming mechanism of the device.  
           [0021]    Another object of the invention is to provide an apparatus as described in the preceding paragraphs which also includes fluid flow rate control locking means for locking the support disk in a preset position so that the rate control can be set only by the treating physician or an authorized health care worker having an operating key.  
           [0022]    Another object of the invention is to provide a novel infusion means for use in delivering the medicinal fluid to the patient.  
           [0023]    By way of summary, the improved fluid delivery apparatus of the present form of the invention comprises five major cooperating subassemblies, namely a reservoir subassembly, a highly novel adjustable, key-operated fluid flow rate control subassembly, a flow indicator subassembly for visually indicating fluid flow through the device fill means for filling the fluid reservoir and infusion means for delivering the medicinal fluid to the patient. The reservoir subassembly, which readily lends itself to automated manufacture, is generally similar to that described in copending Ser. No. 09/165,706 and includes a base and a stored energy means comprising at least one distendable elastomeric membrane which cooperates with the base to form a fluid reservoir. The fluid flow indicator subassembly is also somewhat similar to that described in Ser. No. 09/165,706 and comprises a mechanical fluid flow indicator that provides a clear visual indication of normal fluid flow and absence of fluid flow either because the reservoir is empty or because the flow lines are occluded. Additionally, the apparatus of the invention includes fill means for use in filling the reservoir of the reservoir subassembly and priming means for filling the fluid passageways of the device prior to the commencement of the fluid delivery step. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    [0024]FIG. 1 is a generally perspective view of one form of the apparatus of the present invention which includes a flow indicator means for indicating fluid flow as well as a novel adjustable flow rate control means for precisely controlling the rate of fluid flow from the reservoir of the apparatus  
         [0025]    [0025]FIG. 2 is a generally perspective, exploded view of the apparatus of the invention shown in FIG. 1.  
         [0026]    [0026]FIG. 3 is a top plan view of the apparatus shown in FIG. 1.  
         [0027]    [0027]FIG. 4 is an enlarged, side-elevational view of the apparatus illustrated in FIG. 1 shown partly in cross section to illustrate internal construction.  
         [0028]    [0028]FIG. 5 is a greatly enlarged, front view of the delivery component of the apparatus shown in FIG. 1.  
         [0029]    [0029]FIG. 6 is a cross-sectional view taken along lines  6 - 6  of FIG. 5.  
         [0030]    [0030]FIG. 7 is a cross-sectional view taken along lines  7 - 7  of FIG. 5.  
         [0031]    [0031]FIG. 8 is a view taken along lines  8 - 8  of FIG. 7.  
         [0032]    [0032]FIG. 8A is a view taken along lines  8 A- 8 A of FIG. 8.  
         [0033]    [0033]FIG. 8B is a greatly enlarged view of the area designated as “ 8 B” in FIG. 8A.  
         [0034]    [0034]FIG. 9 is a fragmentary view taken along lines  9 - 9  of FIG. 8.  
         [0035]    [0035]FIG. 10 is a greatly enlarged view of the area designated as “ 10 ” in FIG. 7.  
         [0036]    [0036]FIG. 11 is a view taken along lines  11 - 11  of FIG. 8.  
         [0037]    [0037]FIG. 11A is a cross-sectional view taken along lines  11 A- 11 A of FIG. 8.  
         [0038]    [0038]FIG. 12 is a cross-sectional view taken along lines  12 - 12  of FIG. 11A.  
         [0039]    [0039]FIG. 13 is an enlarged view of the area designated as “ 13 ” in FIG. 12.  
         [0040]    [0040]FIG. 14 is an enlarged, cross-sectional view of the central portion of FIG. 6 showing the bypass passageway of the device for bypassing the fluid flow rate control means of the invention.  
         [0041]    [0041]FIG. 15 is a view similar to FIG. 14 but showing the priming shaft moved to a second, fluid diverting position.  
         [0042]    [0042]FIG. 16 is a generally perspective, exploded rear view of the forward portion of the fluid delivery component of the apparatus.  
         [0043]    [0043]FIG. 17 is a generally perspective, exploded front view of the forward portion of the fluid delivery component.  
         [0044]    [0044]FIG. 18 is a greatly enlarged, side-elevational view of the physician&#39;s key of the invention.  
         [0045]    [0045]FIG. 19 is a view taken along lines  19 - 19  of FIG. 18.  
         [0046]    [0046]FIG. 20 is a generally schematic view showing the fluid flow path through the device during the priming step.  
         [0047]    [0047]FIG. 20A is a generally schematic view similar to FIG. 20, but showing the fluid flow path through the device during the fluid delivery step.  
         [0048]    [0048]FIG. 21 is an enlarged, cross-sectional view taken along lines  21 - 21  of FIG. 9.  
         [0049]    [0049]FIG. 22 is a cross-sectional view taken along lines  22 - 22  of FIG. 21.  
         [0050]    [0050]FIG. 23 is a cross-sectional view taken along lines  23 - 23  of FIG. 21.  
         [0051]    [0051]FIG. 24 is a cross-sectional view similar to FIG. 22, but showing the key housing rotated through an angle to 90 degrees.  
         [0052]    [0052]FIG. 25 is a cross-sectional view similar to FIG. 23, but showing the key housing rotated through 90 degrees and a locking shaft moved into a non-locking position so that the diverter shaft can be moved into its second advanced position.  
         [0053]    [0053]FIG. 26 is an enlarged, cross-sectional view of the area designated as “ 26 ” in FIG. 24.  
         [0054]    [0054]FIG. 27 is a cross-sectional view taken along lines  27 - 27  of FIG. 21.  
         [0055]    [0055]FIG. 28 is a generally perspective, diagrammatic view of the priming shaft and a portion of the flow rate control mechanism of the apparatus of the invention and also showing a portion of the lock-out means of the apparatus of the invention in a normal lock-out configuration.  
         [0056]    [0056]FIG. 28A is an enlarged, cross-sectional view taken along lines  28 A- 28 A of FIG. 28.  
         [0057]    [0057]FIG. 29 is a view similar to FIG. 28, but showing movement of the lockout means to a position permitting inward movement of the priming shaft to prime the fluid passageways of the device.  
         [0058]    [0058]FIG. 30 is a cross-sectional view similar to FIG. 27, but showing the locking shaft having been moved into a position to permit rotation of the flow rate control knob.  
         [0059]    [0059]FIG. 31 is also a view similar to FIG. 28, but showing movement of the lock-out means to a position shown in FIG. 30 that enables rotation of the control member of the fluid flow rate control means of the invention.  
         [0060]    [0060]FIG. 32 is a generally perspective, exploded view of ant alternate form of flow rate control means of the invention.  
         [0061]    [0061]FIG. 33 is a view taken along lines  33 - 33  of FIG. 32.  
         [0062]    [0062]FIG. 34 is a rear view of the alternate form of the rate control means partly broken away to show internal construction.  
         [0063]    [0063]FIG. 35 is an enlarged, cross-sectional view taken along lines  35 - 35  of FIG. 34.  
         [0064]    [0064]FIG. 36 is an exploded, cross-sectional view of the assemblage shown in FIG. 35. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0065]    Referring to the drawings and particularly to FIGS. 1 through 4, one form of the apparatus of the invention is there illustrated and generally designated by the numeral  25 . The apparatus is somewhat similar to that shown in FIGS. 26 through 37 of incorporated-by-reference Ser. No. 09/165,706 and comprises five major cooperating subassemblies namely, a reservoir subassembly  27 , an adjustable flow rate control subassembly  29  (FIG. 4), a flow indicator subassembly  31 , fill means for filling the fluid reservoir of the reservoir subassembly and infusion means for delivering the medicinal fluid to the patient.  
         [0066]    Considering first the reservoir subassembly, the details of which are best seen in FIG. 4, this subassembly includes a base assembly  32 , a stored energy source, shown here as a distendable membrane  34 , and a cover  36  for enclosing the stored energy source. The base assembly includes an ullage substrate  38  and a membrane capture housing  40  having a bottom opening  42  which receives the distendable membrane engaging element or protuberance  44  of ullage substrate  38 . Membrane  34  cooperates with ullage substrate  38  to form fluid reservoir  45 . The ullage substrate, or base  38 , also includes fill means, shown here as a fill assembly  46 , the details of which are described in U.S. Pat. Nos. 5,962,794, 6,086,561, and 6,105,442 issued to one of the present inventors, which patents are hereby incorporated by reference as though fully set forth herein.  
         [0067]    The major difference between the present embodiment of the invention and that shown in FIGS. 26 through 37 of incorporated Ser. No. 09/165,706 is the differently configured flow rate control means of the invention, which functions to precisely control the rate of fluid flow from the device. This rate control means here comprises an adjustable rate control mechanism that is carried by a support means shown here as a superstructure  50  which includes first and second faces  50   a  and  50   b  (see FIGS. 7, 16, and  17 ). Superstructure  50  is connected to base assembly  32  and cover  36  in the manner best seen in FIGS. 2 and 4. The details of construction of this important flow rate control means will presently be described.  
         [0068]    As best seen in FIG. 4, superstructure  50  of the support means includes an outwardly extending fluid inlet protuberance  56  which is closely receivable within a socket like cavity  58  formed in an extension member  60  (see also FIGS. 7, 16 and  17 ). Extension member  60  also has a fluid inlet protuberance  62  that is received within a socket-like cavity  64  formed in base member  32 . Further, extension member  60  also has a pair of arcuate connector elements  66  (FIG. 16) that are mateably received within arcuate slots  68  formed in base assembly  32  (FIG. 2). When the support means, which includes extension member  60 , is mated with base assembly  32 , and connector elements  66  are received within slots  68 , a fluid inlet passageway  70  formed in protuberance  62  of the extension member, is placed in fluid communication with reservoir  45  via passageways  74  and  76 . Similarly, a fluid passageway  78  is formed in protuberance  56  and communicates with passageway  70  of protuberance  60  (FIG. 7).  
         [0069]    With the construction described in the preceding paragraph, when fluid is forced through reservoir outlet  80  by the stored energy means, the fluid will flow into passageway  74 , into passageway  76 , into passageway  70  and then into passageway  78  formed in protuberance  56 . Next, the fluid will flow into a passageway  82  formed in face  84  of a cover member  86  that is disposed in engagement with face  50   b  of superstructure  50  (FIGS. 4 and 16). For purposes presently to be described, passageway  82  is generally “Y” shaped having two branches  82   a  and  82   b.  As indicated by the arrows  91  in FIG. 16, during the normal fluid delivery step, branch  82   a  communicates with chamber  90  formed in a distendable, elastomeric first boot  92  of the flow indicator means of the invention, which is generally similar to that described in incorporated-by-reference Ser. No. 09/165,706. In addition to first boot  92 , the indicator means also comprises a second boot  94  having a chamber  94   a.    
         [0070]    As best seen in FIG. 16, both of the boots  92  and  94  are mounted within oval shaped openings  96  formed in an indicator base  98 . Boots  92  and  94  are of similar construction to boot  266  shown in FIG. 13A of incorporated-by-reference Ser. No. 08/768,663 and reference should be made to this application for a more complete discussion of the construction and operation of the flow indicator boots. As indicated in FIG. 17, each of the boots have a yieldably distendable fluid flow blocking body portion  99   a  which is circumscribed by a marginal portion  99   b.  Marginal portion  99   b  is clamped between cover member  86  and boot-supporting indicator base  98  so that the boot extends through the oval shaped openings  96  formed in the indicator base.  
         [0071]    It is to be understood that the fluid flowing from reservoir  45  in the direction of arrow  103  (FIG. 16) will enter branch  82   a  of passageway  82  and will then flow in the direction of arrow  91  and will impinge upon boot  92 . The flow will be diverted in the direction of arrows  105  of FIG. 16 and will flow rearwardly toward cover  86  and into a passageway  108  which is formed in cover  86 . When cover  86  is abutted against superstructure  50 , passageway  108  will communicate with an axial passageway  110  formed in hub  109  of the flow rate control mechanism. After flowing through the flow rate control means in a manner presently to be described, the fluid will flow toward boot  94  in the direction of the arrows  111  of FIG. 16. After impinging on boot  94 , the fluid will be diverted in the direction of the arrows  113 , through an aperture  114  formed in cover  86  and onwardly toward superstructure  50 . Upon reaching superstructure  50 , the fluid will flow into a passageway  116  where it will be directed in the direction of arrows  117  toward the outlet  118  of the device housing  120  with which the infusion means of the invention communicates (FIG. 1).  
         [0072]    It is to be observed that fluid flowing from reservoir  45  toward boot  90  is under a higher pressure than fluid flowing toward boot  94 . This is because the pressure of the fluid flowing toward boot  94  has been reduced as a result of the fluid flowing through rate control means of the invention. As will be discussed more fully in the paragraphs which follow, this result enables incorporation with a pair of indicator films (presently to be described) a determination of the various fluid flow operating conditions of the device namely normal fluid flow, fluid flow blockage or occlusion, and reservoir empty.  
         [0073]    Turning particularly to FIGS. 2, 16, and  17 , in addition to indicator base  98  within which boots  90  and  94  are mounted, the flow indicator means also comprises a support or lens plate  124 , and a hollow forward housing  126  (FIG. 2) within which the indicator base  98  and the superstructure  50  are enclosed. As shown in FIGS. 2 and 17, a viewing lens  128  is viewable through an aperture  126   a  provided in forward housing  126 . Disposed between indicator base  98  and lens plate  124  are first and second indicia-carrying means, which are of the character previously mentioned, and shown here as a pair of closely adjacent, thin films  130  and  132 . These films are virtually identical in construction and operation to films  306  and  308  of the embodiment described in incorporated by reference Ser. No. 08/768,663 and, for a more complete understanding of the construction and operation of these films, reference should be made to this application and particularly to FIGS. 12 and 13 thereof and to the discussion of these figure drawings in the specification of the application. Films  130  and  132  are in intimate contact and are preferably constructed from a substantially transparent, flexible polymer material such as mylar. The downstream surface of the inferior or first film  130  is printed with three integrated symbols (see FIG. 12 of U.S. Ser. No. 08/768,663), which may comprise, by way of example, a blue circle, a green arrow, and a red X, each consisting of diagonal strips of color printed in an alternating pattern (blue, green, red, blue, green, red, and so on). The second film  132  serves as a “mask” over film  130  and is printed with a pattern of diagonal alternating clear and opaque strips that occur in approximately a  1 : 2  ratio. The printed ratio of the “mask” allows only one colored symbol to appear at a time when viewed through viewing lens  128 . As in the embodiments described in U.S. Ser. No. 08/768,663, the inferior and superior films are provided at their apertures  135  which receive retention pins  136  provided on indicator base  98  (FIG. 17) which permit attachment of the films to platform  98  in a manner such that the non-patterned portions of each film covers boot openings  96   a  provided proximate each end of indicator base  98  with the patterned portions of both the superior and inferior films being maintained in index. With this construction, each thin film is able to move in response to pressure exerted thereon by the elastomeric boots  92  and  94  in opposing directions parallel to the film plane with its range of motion limited to one axis in the film plane by appropriate edge guides provided on indicator base  98 . As more fully described in U.S. Ser. No. 08/768,663, as the films move, the visible symbol pattern will, of course, change due to the transverse displacement of the patterns imprinted thereon.  
         [0074]    As is apparent from a study of FIGS. 13 and 13A of incorporated by reference U.S. Ser. No. 08/768,663, the central portions of both the first and second elastomeric actuator elements or boots  92  and  94  will be deflected outwardly toward plate  124  when the device is filled, but not in a state of delivery or when there is a build up of fluid pressure during delivery that is caused by blockage of the delivery line downstream from boot  94 . While boot  92  can be deflected by normal line pressure, boot  94  is deflected only by pressure buildup resulting from the downstream blockage. When both elastomeric boots  90  and  94  are deflected outwardly, both the superior and inferior films are displaced transversely to a second position revealing a second symbol, as for example, an X as viewed through the viewing aperture of the support plate. When fluid is flowing through the device, an indicia such as an arrow is visable through the viewing window.  
         [0075]    A third alignment of symbol patterns is visible when the device is in an unfilled state or when the delivery line is open, the reservoir is empty and fluid delivery to the patient has been completed. In this case, there is no fluid pressure in the line on either the upstream or the downstream side of the flow control means and thus both the first and second boots are in a non-deflected position. In this condition, the inferior and superior films are not transversely displaced and thus exhibit a third combination of patterns resulting in a third symbol as, for example, a circle being visible through the viewing aperture of the support plate. Boots  90  and  94  can be precisely tailored to deflect under various pressures thereby permitting great apparatus versatility. Reference should also be made to U.S. Ser. No. 08/432,221, which application was incorporated by reference in U.S. Ser. No. 08/768,663, for a further discussion of the construction and operation of the indicator means of the invention.  
         [0076]    Considering next the important priming means of the invention for priming the fluid passageways of the device before commencing the fluid delivery step. This important means here comprises an elongated diverter shaft  140  that forms a part of the diverter means of the invention for causing the fluid flowing from the reservoir toward the housing or device outlet  118  to bypass the fluid flow rate control means so as to enable rapid priming of the fluid flow paths of the apparatus, including the dispenser line. In the present form of the invention, diverter shaft  140  is mounted within housing  86   a  in the manner best seen in FIGS. 6 and 7. As will presently be discussed, the diverter shaft can be moved by finger pressure from the at-rest, extended position shown in FIGS. 6, 14, and  28  to the advanced priming position shown in FIGS. 15 and 29.  
         [0077]    Referring particularly to FIGS. 6, 14, and  15 , it is to be noted that diverter shaft  140  is provided with a fluid chamber  142  having an inlet  144  and an outlet  146  (see also FIG. 28). When shaft  140  is in the priming position shown in FIGS. 15 and 29, inlet  144  is in communication with branch  82   b  of passageway  82  and outlet  146  is in communication with a passageway  148  formed in a flow rate control housing and manifold  150  that is connected to superstructure  50  (FIGS. 4 and 6). With shaft  140  in its advanced or priming position, fluid can flow from reservoir  45  into branch  82   b,  into shaft chamber  142  and through the chamber into passageway  148 . As indicated in FIG. 17, the fluid flowing into passageway  148  can then flow into the bypass passageway  152  formed in manifold  150  and into stub passageway  154  that communicates with boot  94 . In this way, the various fluid passageways that comprise the fluid flow path of the device can be primed without the fluid that normally enters passageway  78  of protuberance  56  having to flow through the flow rate control means of the invention. With this novel arrangement, the time for priming the device is substantially reduced, which is essential in an ultra low flow rate device of the character described here. When the various passageways of the flow path are primed, and an inward pressure on diverter shaft  140  is removed, biasing means, shown here as spring  173 , will automatically return the diverter shaft to its starting position as shown in FIG. 14 wherein fluid flow into bypass passageway  152  is blocked.  
         [0078]    Turning to FIG. 20, which comprises a somewhat simplified schematic depiction of the fluid flow path through the device, it can be seen that during the priming step fluid will flow via a first fluid passageway segment  155  from reservoir  45  toward first boot  92  and via a second or bypass segment  157  toward second boot  94  and then onto the device outlet  118  to which the dispenser line of the infusion means is connected. As indicated in FIG. 20, fluid can also flow via a gas vent  159  toward, but not through the downstream outlet  29   b  of the fluid flow rate control means or rate control assembly  29 . With the construction shown in FIG. 20, fluid can also flow toward the upstream inlet  29   a  of the rate control subassembly. Thus, as indicated in FIGS.  20 , and by way of summary, fluid can flow via first segment  155  from reservoir  45  into boot  92 , toward the inlet  29   a  of the rate control subassembly via third segment  161  and also toward diverter shaft  140 . When the diverter shaft is in the prime position shown in FIG. 20, fluid can flow through the chamber  142  formed in the shaft, into bypass segment  157  toward outlet  118 , toward boot  94  and also toward the outlet  29   b  of the rate control assembly. In this way all the fluid passageways of the device that comprise the flow path are quickly and positively primed.  
         [0079]    Referring to FIG. 20A, it is to be noted that when the diverter shaft  140  is in its normal retracted position, as there shown, fluid can flow toward the device outlet  118  via the fluid flow rate control subassembly  29  in a normal manner. More particularly, fluid will initially flow, via first segment  155 , toward first boot  92 . From boot  92 , fluid will flow, via third segment  161 , toward the rate control assembly and then onto second boot  94  via gas vent  159 . From boot  94 , fluid will flow toward the device outlet  118  in the manner shown in FIG. 20A.  
         [0080]    By way of reconciliation of FIGS. 20 and 20A with the previously described figure drawings, and in particular FIGS. 16 and 17, segment  155  as shown in FIG. 20 comprises flow passageways  74 ,  76 ,  78  (FIG. 4) and passageway  82   a  (FIG. 16). Similarly, second segment  157 , as shown in FIG. 20, comprises passageways  82   b,    152  and  116  (FIG. 16), while third segment  161  comprises passageways  108  and  110  (FIG. 16).  
         [0081]    Another novel feature of the invention resides in the provision of diverter shaft locking means for preventing unauthorized advancement of diverter shaft  140  into the second priming position shown in FIGS. 15, 19, and  29 . This important means here comprises a key housing  158  that is rotatably carried within a first cavity  160  formed in extension member  60  (FIG. 16) and is held in position with the device housing by a “C” shaped locking ring  158   b  (FIG. 21). Ring  158   b  engages a shoulder formed on an upper housing  163  that secures key housing  158  in place (see also FIG. 16). As shown in FIG. 23, an indexing rib  158   c  is receivable within a selected one of grooves  60   c  formed in extension  60 . Cavity  160  includes a generally key-shaped opening  160   a  that is accessible from the bottom of extension  60  and housing  126  so that the end  162   a  of physician&#39;s key  162  (FIGS. 18 and 19) can be inserted into opening  160   a  to impart rotation to housing  158  (FIGS. 1, 11,  18 , and  19 ).  
         [0082]    As shown in FIGS. 28 and 29, key housing  158  has a gear segment  164  that meshes with a mating gear segment  166   a  formed on a generally vertically extending locking shaft  166  that also comprises a part of the diverter shaft locking means. Locking shaft  166  is received within a second cavity  167  formed in extension member  60  and is positioned therewithin so that gear segment  166   a  meshes with the gear segment  164  of key housing  158 . A finger  50   f  extends from superstructure  50  and serves to hold shaft  166  in position (FIGS. 16 and 30). When locking shaft  166  is in the first retracted, or normal, position shown in FIG. 28, the shaft engages a shoulder  170  formed on diverter shaft  140  (FIG. 23). However, as shown in FIGS. 24, 25, and  29 , upon rotation of locking shaft  166  through an angle of 90 degrees in the direction of arrow  169  of FIG. 29, flat  168  will move into a position that will permit shoulder  170  to bypass the locking shaft so that the diverter shaft  140  can be moved into the advanced, second position shown in FIGS. 25 and 29.  
         [0083]    Upon release of the turning pressure exerted on the physician&#39;s key, a first biasing means shown here as an arcuate coil spring  172  which circumscribes the key housing (FIGS. 24 and 26) and is disposed between protuberances  172   a  and  172   b  (FIG. 22) will urge the key housing as well as locking shaft  166  to tend to return to their starting positions. Similarly, removal of the inward pressure exerted by the operator on the diverter shaft  140  will cause the diverter shaft to automatically return to its extended starting position due to the urging of second biasing means shown here as a coil spring  173 . As illustrated in FIGS. 16, 17,  23  and  25 , spring  173  is held captive between a shoulder  174  formed on the diverter shaft and an end clip  176  that is connected to extension member  60  (FIG. 16).  
         [0084]    Considering next the details of the novel flow rate control means of the invention, this important means here comprises a rate control assembly  180  that is mounted for rotation on hub  109  of superstructure  50  (FIG. 16). Assembly  180  includes a rate control element base  182 , a housing  183  and a back plate  184  having teeth  184   a  formed about its periphery (FIGS. 8, 10, and  16 ). Assembly  180  is controllably rotated about hub  109  by a smaller diameter driving member shown here as a toothed wheel  186  having teeth that mesh with teeth  184   a.  Wheel  186  is, in turn, driven by a finger engaging control knob  190  which, as shown in FIGS. 8 and 16 includes a knurled periphery  190   a,  a portion of which extends through an opening  192  formed in the forward housing portion  126  (FIG. 2). Control knob  109  also has teeth which mesh with toothed wheel  186  so that rotation of knob  190  about a spindle  194  (FIG. 8) formed on superstructure  50  will impart rotation to wheel  186  about a spindle  196  and will also impart rotation to assembly  180  about hub  109 . Spindle  194  is provided with an indexing rib  194   a  that mates with a selected one of the grooves  191  provided on knob  190  so as to properly index the knob on spindle  194  (see FIGS. 11A, 12 and  13 ). With this construction, by rotating knob  190 , a selected one of a plurality of rate control elements  199  carried by rate control element housing  182  in the manner shown in FIG. 8 can be moved into alignment with a passageway  200  of superstructure  50  (FIGS. 8 and 16) so that fluid flowing from reservoir  45  will flow therethrough at a controlled rate. After flowing through the selected rate control element, the fluid will then flow in the direction of the arrows  111  of FIG. 16 toward boot  94  and then rearwardly in the direction of the arrows  113  in the direction of device outlet  118 .  
         [0085]    The rate control elements  199  of the flow rate control means of the invention can take several forms, but in the embodiment of the invention shown in FIGS.  1  through  31 , these elements comprise glass, flow rate control capillaries  202 , each having a microbore  202   a  of a selected size that carries the fluid through the rate control element (FIGS. 8 and 10). As best seen in FIG. 8B, capillaries  202  include an elastomer body  202   b  within which the glass capillary  202   c  is secured. Glass capillary  202   c  is coated with a polyimide coating  202   d  that is sealably connected to body  202   b.  Capillaries  202  are commercially available from sources such as Polymicro, Inc. of Phoenix, Ariz. Elements  199  are carried by the control member or base  182  of assembly  180  so that each communicates with a radially extending fluid flow passageway  206  formed within the assembly. Each of the passageways  206 , in turn, communicates, at their inlet  206   a,  with passageway  110  that communicates with boot  92  in the manner previously described.  
         [0086]    As the rate control assembly is rotated by rotation of control knob  190 , a selected one of the passageways  206  containing a selected rate control element or capillary  202  is brought into fluid communication with fluid flow passageway  200 . Element  202  will, of course, precisely control the rate of fluid flowing toward passageway  200  and ultimately toward device outlet  118  via the fluid flow path of the device. When a different flow rate is desired, the control knob can be conveniently rotated to bring another passageway  206  into communication with outlet  29   b.  To assist the caregiver in selecting a desired fluid flow rate, rate control graphics  207  are viewable through an opening  207   a  formed in the device housing (see FIGS. 1, 2, and  9 ).  
         [0087]    Another important aspect of the invention resides in the provision of rate control locking means for preventing the unauthorized setting of rate controls by the rotation of driving member or control knob  190 . This novel rate control locking means here comprises the previously identified key housing  158  as well as the generally vertically extending locking shaft  166 . As previously mentioned, housing  158  is rotatably carried within first cavity  160  formed in extension member  60  (FIG. 16), which cavity includes a generally key-shaped opening  160   a  that is accessible from the bottom of extension  60  so that the physician&#39;s key  162  can be used to rotate the key housing in the manner previously described.  
         [0088]    When locking shaft  166  is in the first normal position shown in FIGS. 27 and 28, the shaft positively prevents rotation of the control knob  180  by engaging an octagonal shaped member  210  that forms a part of control knob assembly  180  (FIGS. 28 and 28A). As previously discussed and as shown in FIGS. 24, 25, and  29 , upon rotation of locking shaft  166  through an angle of 90 degrees in the direction of arrow  169  of FIG. 29 shaft  166  will move into a position that will permit operation of the diverter shaft  140 . However, with the shaft in this second position, rotation of the control knob is still prevented thus preventing accidental resetting of the fluid flow rate. On the other hand, rotation of key housing  158  in the direction of the arrow  211  of FIG. 31, will cause the shaft  166  to move into the position shown in FIG. 31 where in a second flat  214  formed on the shaft moves into a position that will allow free rotation of the control knob in the direction of the arrow  215  (see also FIG. 30). As before, when the turning force exerted on the physician&#39;s key ceases, the arcuate coil spring  172  which circumscribes the key housing (FIGS. 24 and 26) will urge the key housing and the locking shaft  166  to tend to return to their starting positions thereby locking the control knob against further rotation.  
         [0089]    Referring to FIG. 11, it is to be noted that indicia provided on the lower surface of cover  126  guides the caregiver in accomplishing the priming and rate control setting steps. For example, after the physician&#39;s key is inserted into opening  160   a  a rotation of the key in the direction of the counterclockwise arrow will move the locking shaft into the position shown in FIG. 29 permitting movement of the diverter shaft into the priming position. Similarly, rotation of the physician&#39;s key in the direction of the clockwise arrow of FIG. 11, will move the locking shaft into the position shown in FIG. 31 permitting rotation of the control knob  190  to set the desired rate of fluid flow to the patient. It is to be noted that the locking key cannot be removed until housing  158  and key  162  return to their initial starting position.  
         [0090]    Turning to FIGS. 32 through 36 an alternate form of flow rate control means of the invention is there illustrated. This alternate means is similar in some respects to that previously described herein and like numerals are used to identify like components. As before, this alternate means comprises a rate control assembly that is rotatably mounted on hub  109  of superstructure  50  (FIG. 32). The alternate rate control assembly, here designated as  220 , includes a rate control element base  222 , a housing  224  and a back plate  226  having teeth  227  formed about its periphery. Assembly  220  is controllably rotated about hub  190  by a smaller diameter driving member, or toothed wheel (not shown) which is, in turn, driven by a finger engaging knob (not shown) both of which are of the character previously described. As before, the control knob rotates about a spindle  194 , while the toothed wheel rotates about a spindle  195  to impart rotation to assembly  220  about hub  109 . As best seen in FIG. 32, housing  224  is provided with a hub  225  that is rotatably supported within an aperture  225   a  formed in the flow rate control housing of the device, the character of which will presently be described.  
         [0091]    The primary difference between this latest form of flow rate control means of the invention and that earlier described resides in the replacement of the capillary type rate control elements with rate control elements comprising axially extending laser drilled microbores  228   a  formed in a rate control disc  228 . As before base  222  is provided with a plurality of radially extending fluid passageways  229  (FIG. 34). However, in this instance, each of the passageways  229  communicates with a selected one of a plurality of spaced-apart apertures  231  formed in base  222  (FIG. 33). As best seen in FIGS. 35 and 36, rate control disc  228  is sealably disposed between base  222  and housing  224 , the latter of which is provided with circumferentially spaced outlets  224   a  that communicate with a flow passageway  233  formed in a flow rate control housing  235  which is similar in construction and purpose to flow rate control housing  150  of the earlier described embodiment. Passageway  233  communicates with a passageway  237  formed in a member  240  that is received within superstructure  50 . A plurality of circumferentially spaced O-ring elastomeric seals  242  are mounted on base  224  to prevent leakage of fluid internally of housing  224 . As in the earlier described embodiment, fluid flowing through a selected rate control microbore will flow into passageway  233  and then toward boot  94  in the manner previously described. Vent means in the form of a porous hydrophobic vent  233   a  is provided (FIG. 35) and is held in position by a cover  233   b.  In operation, by rotating the control knob of the device, it is apparent that a selected passageway  229  and a microbore of a selected size can be positioned within housing  235  so as to communicate with passageways  233  and  237  and ultimately with device outlet  118 . In this way the rate of fluid flow toward outlet  118  and then toward the patient can be precisely controlled. It is to be understood that the priming and locking functions previously described can be accomplished in the same manner with similar structure.  
         [0092]    The fifth major subassembly of the invention, namely the infusion means for delivering the medicinal fluid to the patient is usable with both the previously described forms of the invention. This important means comprises a conventional delivery line  250  that is interconnected with the device outlet  118  in the manner shown in FIG. 1. In addition to the delivery line  250 , the infusion means of the invention also includes a line clamp  252  which is of conventional construction and a gas vent and filter unit  254  which is also of a conventional construction well known to those skilled in the art.  
         [0093]    Once the adjustable flow rate control means of the invention has been set in the manner described in the preceding paragraphs and the fluid flow path has been primed, the infusion cannula  256   a  of the cannula assembly  256  of the invention (FIG. 3) can be invasively interconnected with the patient and the fluid delivery step can commence. During the delivery step, fluid will flow toward the patient at the rate of flow selected by the caregiver at the time of setting the fluid flow rate control means of the invention. In the manner previously described, the fluid status of the device can be continuously monitored by observing the various flow symbols of the indicator means that appear through viewing window  128  of the apparatus.  
         [0094]    Having now described the invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difficulty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth in the following claims.