Abstract:
A fluid delivery device having a self-contained stored energy membrane for expelling fluids at a precisely controlled rate, which is of a compact, laminate construction. The device is of very low profile so that it can conveniently be used for the precise delivery of a small volume of pharmaceutical fluids, such as insulin, morphine and the like, into an ambulatory patient at precisely controlled rates over extended periods of time. The device includes strategically configured, multiple fluid chambers to achieve the maximum possible average percent of extension of the membrane and thereby assure adequate fluid delivery pressure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to fluid delivery devices. More particularly, the invention concerns an improved, ultra-low profile, multiple chamber fluid delivery apparatus for precise subdermal delivery over time of medicinal liquids to an ambulatory patient, the device including novel reservoir filling means. 
     2. Discussion of the Prior Art 
     A number of different types of liquid dispensers for dispensing medicaments to ambulatory patients have been suggested. Many of the devices seek either to improve or to replace the traditional hypodermic syringe that has been the standard for delivery of liquid medicaments such as insulin solution. 
     Those patients that require frequent injections of the same or different amounts of medicament, find the use of the hypodermic syringe both inconvenient and unpleasant. Further, for each injection, it is necessary to first draw the injection dose into the syringe, then check the dose and, after making certain that all air has been expelled from the syringe, finally, inject the dose. This cumbersome and tedious procedure creates an unacceptable probability of debilitating complications, particularly for the elderly and the infirm. 
     One example of the urgent need for an improved liquid delivery device for ambulatory patients can be found in the stringent therapeutic regimens used by insulin-dependent diabetics. The therapeutic objective for diabetics is to consistently maintain blood glucose levels within a normal range much as the normally functioning pancreas would do by secreting a very low level of extremely fast-acting insulin at a basal rate into the blood stream throughout the day and night. 
     As will be appreciated from the discussion that follows, the low profile apparatus of the present invention is uniquely suited to provide precise fluid delivery management at a low cost in those cases where a variety of precise dosage schemes are of utmost importance. 
     An additional important feature of the apparatus of the present invention is the provision of a novel reservoir filling means disposed on the underside of the base. 
     Because the embodiments of the invention described herein comprise improvements to the devices described in U.S. Pat. No. 5,957,891 issued to Kriesel et al on Sep. 28, 1999, this patent is hereby incorporated by reference in its entirety as though fully set forth herein. 
     With regard to the prior art, one of the most versatile and unique fluid delivery apparatus was developed by Kriesel and described in U.S. Pat. No. 5,205,820. The components of this novel fluid delivery apparatus generally include: a base assembly, an elastomeric membrane serving as a stored energy means, fluid flow channels for filling and delivery, flow control means, a cover and an ullage which comprises a part of the base assembly. Another unique multiple chamber, reservoir type fluid delivery apparatus developed by Kriesel is described in U.S. Pat. No. 5,336,188. This novel fluid delivery apparatus includes, an elastomeric membrane that serves as a stored energy means and cooperates with the base of the apparatus to define a multi-part reservoir. 
     Another useful liquid delivery device is that described in U.S. Pat. No. 5,514,097 issued to Knauer. The Knauer device comprises a medicament injection apparatus for subcutaneous or intramuscular delivery of a medicament that conceals the infusion needle behind a needle shroud. On apparatus activation, the needle is thrust forward, pushing the needle tip outside the needle shroud with enough force to puncture the skin. The needle is thus automatically introduced into the tissue at the proper needle/skin orientation. In the same action, the apparatus automatically dispenses an accurate pre-set dose. 
     U.S. Pat. No. 5,226,896 issued to Harris also described a useful prior art device. This device comprises a multidose syringe having the same general appearance as a pen or mechanical pencil. The Harris device is specifically adapted to provide for multiple measured injections of materials such as insulin or human growth hormones. 
     Still another type of liquid delivery device is disclosed in U.S. Pat. No. 4,592,745 issued to Rex et al. This device is, in principle, constructed as a hypodermic syringe, but differs in that it enables dispensing of a predetermined portion from the available medicine and in that it dispenses very accurate doses. 
     The present invention seeks to significantly improve over the prior art by providing a novel, ultra-low profile fluid delivery device having strategically configured, multiple fluid chambers and a unique filling means for filling the fluid chambers of the device. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an apparatus having a self-contained stored energy membrane for expelling fluids at a precisely controlled rate that is of a compact, laminate construction. More particularly, it is an object of the invention to provide such an apparatus which is of very low profile so that it can conveniently be used for the precise delivery of pharmaceutical fluids, such as endocrine type agents such as insulin, growth hormones and the like, into an ambulatory patient at controlled rates over extended periods of time. 
     It is another object of the invention to provide an apparatus of the aforementioned character that is highly reliable and very easy-to-use by lay persons in a non-hospital environment. 
     Another object of the invention is to provide an apparatus of the character described in the preceding paragraphs which includes novel reservoir filling means for conveniently filling the fluid reservoir of the device. 
     Another object of the invention is to provide an apparatus of the character described which includes a novel fill adapter which permits filling of the reservoir of the apparatus only with filling means of a specific construction, which is designed so that the fill adapter is irreversibly installed and, once installed, cannot be removed from the device housing. 
     Another object of the invention is to provide an apparatus such as that described in the preceding paragraph in which the reservoir fill means includes integrated structure to accept conventional prefilled pharmaceutical vials. 
     Another object of the invention is to provide an apparatus of the class described which further includes delivery means for precisely delivering medicinal fluids to the patient including the provision of a novel, dynamically mounted cannula assembly. 
     Another object of the invention is to provide an apparatus of the type described which includes indicator means for indicating fluid flow from the device reservoir. 
     Another object of the invention is to provide an apparatus of the character described which, due to its unique construction, can be manufactured inexpensively in large volume by automated machinery. 
     Other objects of the invention will become apparent from the discussion that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of one form of the fluid delivery device of the present invention partly broken away to show internal construction. 
     FIG. 2 is a cross-sectional view taken along lines  2 — 2  of FIG.  1 . 
     FIG. 3 is a cross-sectional view taken along lines  3 — 3  of FIG.  1 . 
     FIG. 4 is a generally perspective, exploded view of the apparatus of the invention shown in FIGS. 1 and 2. 
     FIG. 5 is a view taken along lines  5 — 5  of FIG.  4 . 
     FIG. 6 is a side-elevational, cross-sectional view similar to FIG. 2, but showing the fluid chambers of the device filled with fluid. 
     FIG. 6A is a diagrammatic view of an elastomeric membrane stretched into a generally dome shaped configuration. 
     FIG. 6B is a diagrammatic view of an elastomeric membrane stretched into a pair of side-by-side, dome-shaped segments. 
     FIG. 7 is a generally perspective view of an alternate form of fluid delivery device of the invention. 
     FIG. 7A is a generally perspective fragmentary view of another form of infusion means of the invention. 
     FIG. 7B is a greatly enlarged, cross-sectional view taken along lines  7 B— 7 B of FIG.  7 A. 
     FIG. 8 is an enlarged, top plan view of the housing and fill means of the invention. 
     FIG. 9 is a cross-sectional view taken along lines  9 — 9  of FIG.  8 . 
     FIG. 10 is a cross-sectional view taken along lines  10 — 10  of FIG.  8 . 
     FIG. 11 is an enlarged, cross-sectional view taken along lines  11 — 11  of FIG.  8 . 
     FIG. 12 is a cross-sectional view taken along lines  12 — 12  of FIG.  8  and rotated 180 degrees. 
     FIG. 13 is an enlarged, fragmentary view of the area designated in FIG. 8 by the numeral  13 . 
     FIG. 14 is a cross-sectional view taken along lines  14 — 14  of FIG.  13 . 
     FIGS. 15A,  15 B are a generally perspective, exploded view of a portion of the embodiment of the invention shown in FIG.  7 . 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring to the drawings and particularly to FIGS. 1 and 2, one form of the fluid delivery device of the invention is there shown and generally designated by the numeral  14 . This form of the invention, which is specially designed for subdermal infusion of selected medicaments, comprises a housing  15  that includes a base  16  having an upper surface  18  including a generally dome shaped central portion  20  and a peripheral portion  22  circumscribing central portion  20 . Base  16  also includes a lower surface  24  to which a patient interconnection means or adhesive pad  26  is connected. Pad  26  which comprises a foam tape having adhesive on both sides functions to releasably interconnect the device to the patient so as to hold it securely in place during the medicament delivery step. A peel-away member  26   a  covers a portion of the lower surface of the pad  26 . 
     A stored energy means cooperates with the upper surface  18  of base  16  and with uniquely configured cover means or cover assembly  30 , to form a plurality of irregularly shaped fluid chambers  32  (FIG.  2 ). Base  16  has an inlet port assembly  34 , that, in a manner presently to be described, is adapted to cooperate with a fill means for filling chambers  32  with the medicinal fluid to be infused into the patient. The stored energy means is here provided in the form of at least one distendable membrane  36  that is superimposed over base  16 . Membrane  36  is distendable from the first position shown in FIG. 2 to the second position shown in FIG. 6 as a result of pressure imparted on the membrane by fluids introduced into the uniquely configured chambers  32  via inlet port assembly  34  (FIG.  2 ). As membrane  36  is distended into its second position in the manner shown in FIG. 6, internal stresses will be established, which stresses tend to move the membrane toward a less distended configuration and in a direction toward upper surface  18  of base  16 . Membrane  36  can be constructed from a single membrane or from multiple membranes that are overlaid to form a laminate construction. 
     Provided within reservoir chambers  32  is ullage defining means for providing ullage within each of the chambers, which ullage means is engaged by membrane  36  as the membrane moves toward its less distended starting configuration. The ullage defining means here comprises the generally dome shaped, annular protuberance  40  formed on base  16 . Ullage  40  circumscribes generally dome shaped protuberance  20  so that when the distendable membrane, after being distended, tends to return toward its less distended configuration, fluid contained within the fluid chambers  32  will flow outwardly toward the infusion means of the invention. 
     Superimposed over base  16  is the previously mentioned cover means, or cover assembly  30 . Cover assembly  30  includes a rigid or semi-rigid cover portion  46  that functions, through the use of novel sealing means, to sealably enclose membrane  36  and a soft elastomer member  38  that overlays portion  46 . The sealing means here comprises a pair of generally circular grooves  48  formed in peripheral portion of base  16  and a pair of cooperating, generally circular shaped rim like protuberances  50  formed on the peripheral lower surface  46   b  of the cover  46 . Protuberances  50  are receivable within grooves  48  in the manner shown in FIGS. 2 and 6 and function to sealably clamp distendable membrane  36  between the cover portion  46  and base  16 . Elastomer covering  38  forms the upper surface of the cover assembly and serves both to enclose chambers  32  and also to make the device more patient friendly. More specifically, as shown in FIGS. 1 and 4, member  38  includes soft edges and corners  38   a  that prevent the edges and corners of the device from causing unnecessary discomfort to the patient. Member  38  also includes a soft, pliable overcover that closes the fluid chamber  32 . While several materials can be used for covering  38 , materials such as a material sold under the name and style “Santoprene” by The Monsanto Company of St. Louis, Mo. has proven satisfactory for this purpose. 
     Examples of materials found particularly well suited for the construction of distendable membrane  36  include certain interpenetrating networks that can comprise silicone polymers silicone polymers. These materials are castable into thin film membranes and have high permeability that allows maximum transport of vapor and gas, high bond and tear strength, excellent low temperature flexibility, radiation resistance and exhibit generally flat stress-strain curves. Additionally, silicone elastomers retain their properties over a wide range of temperatures (−80° to 200° C.) are stable at high temperatures, and exhibit tensile strengths up to 2,000 lb./in 2  elongation up to 600%. Other suitable materials for construction of the stored energy membrane include natural and synthetic latex. 
     Manufacturers of materials suitable for use in construction of the distendable membrane include Dow Chemical, General Electric, B.P. Polymers, Mobay Chemical, Shell Oil Corp., Petrarch Systems, DuPont, Concept Polymers, Goodyear and Union Carbide Corp. 
     With respect to the structural cover  46  and base  16 , these components can also be produced from a variety of materials including one of several polymer groups. The degree of hardness of these materials can range from soft, resilient or rigid, and the following readily commercially available polymers can be employed: Acrylics, polycarbonates, polypropylene (PP), Ultra high molecular weight polyethylene (UHMW PE), High density polyethylene (HDPE), Polyvinylidene Fluoride (PVDF), Ethylene-vinyl acetate (EVA), Styrene Acrylonitrile (SAN), Polytetrafluoroethylene (PTFE). 
     The underlying objective of the present invention is to provide a very low profile patch-type of fluid delivery device that is capable of delivering approximately 1-10 cubic centimeters (cc) of fluid at a constant rate over a prescribed period of time. In the preferred form of the invention, the device uses the stored energy of an elastomeric membrane under tension as the source of pressure for fluid delivery. A linear rate of fluid delivery requires that a relatively constant level of chamber pressure be maintained during fluid delivery. The amount of pressure needed to perform this task is essentially small, however, an increase in the pressure level used is necessary to avoid interference from environmental factors such as shock, vibration, temperature variation or the like perturbations. The relationship of pressure (chamber) to membrane tension can be expressed as follows:        P   =       2      T     R                            
     Where P is equal to the chamber pressure, T is equal to the tension on the membrane and R is equal to the radius of the sphere, of which the arc formed by the inflated membrane is a part (see FIG.  6 A). Tension T is calculated by the following: 
     T=Average % membrane extension times Modulus of elasticity of the membrane material times the Cross section of the area of extended membrane. 
     The average percent extension of the membrane is approximately equal to the ratio between the area of the membrane at rest (in the planar state) and the area of the membrane at extension. The modulus is a material specific parameter. In the following examples, it is assumed that the membrane used is an optimized material having, by way of example, a modulus of about 100 Lbs/in 2 . 
     By way of a first example, a small single-chambered device such as that shown in FIG. 6A having a circular base B that is approximately 1 inch in diameter and a chamber height of 0.25 inch, could be used to demonstrate the performance factors of a simple stored energy membrane type design. The fluid chamber “C” in this example, whose approximate total volume is 1.7 cc, is a small fraction of a sphere whose radius R is 0.625 inch, a value that is relatively large. Filling of the reservoir causes the membrane “M” to extend from the position shown by the horizontal line L in FIG. 6A to the distended position indicated by the line L- 1  as it expands upwards to fill the space allowed. This example yields a low average percent membrane extension of approximately 50%. If the average membrane extension is small and the resulting calculated membrane tension “T” is small, it follows that the pressure P will be very small. More particularly with extended membrane, the pressure P here equals:              2      T     R                   or                   0.5   0.625       =     3.2                 psi                            
     While this pressure level could be used to deliver fluid from the chamber C, the linearity of the fluid delivery rate (flow volume over time) could be adversely affected by changes in environmental conditions such as the ambient temperature. In addition, it should be noted that the single reservoir design shown in FIG. 6A has a functional limit on fluid delivery that is dependent upon the height of the chamber. If the chamber height is decreased beyond a certain point, the average percent membrane extension will be insufficient to provide even the minimum chamber pressure for appropriate fluid delivery. 
     In the second example shown in FIG. 6B, the device membrane has been segregated by a canopy structure into two chambers, each with a base diameter of 0.5 inches and a height of 0.25 inches. Here the fluid volume accommodated by the two chambers would be approximately 2.14 cc. This increase in volume chamber for a same total base diameter of 1.0 inch is a significant advantage over the single chamber design of the first example. Further, the spheres, of which each chamber is a portion, have a radius R of 0.25 inches. The average percent of membrane extension in this example has increased to 100% and it is apparent that the resulting pressure P is significantly higher. More particularly, in this example where:          T   =   1.25     ,       the                 pressure                 P     =           2      T     R                   or                   2.50   0.25       =     10                 psi                                
     This significantly higher pressure is now within a pressure range that will deliver fluid at a rate that will not be adversely affected by changes in environmental perturbations conditions. 
     In the previous examples, a relatively wide tolerance bracket for the linearity of flow is assumed. If, however, the tolerance requirements for linearity of flow are tighter, the use of an ullage such as the protuberance  20  and  40  (FIG. 2) is required to prevent substantial tail off of the fluid delivery rate near the end of delivery cycle. The ullage volume required to maintain linearity of flow at a certain level is a function of the relationship between the radius of the chamber base and the height of the chamber as defined by the membrane in its extended state. This relationship is easiest to model if one assumes the chamber to be spherical in nature as has been assumed in the first and second examples. 
     Assuming that the delivery protocol requires that the linearity of flow rate be maintained within a 10% tolerance window, then the following could be said about the models described in the first and second examples. In the first example, the total volume of the chamber is approximately 1.74 cc. Maintaining a linearity of flow rate within 10% would require an ullage volume of 1.58 cc or 90% of the total chamber volume. This yields a delivery volume of only 0.16 cc, a volume substantially below the anticipated requirements. The total volume of the two chambers in the second example is approximately 2.14 cc. Here, an ullage volume of only 0.76cc would be required to deliver approximately 1.38 cc of fluid with a linearity of flow held to within 10% tolerance discounting other rate control and membrane tolerancing factors. 
     In the embodiment of the invention shown in FIGS. 1 through 6 of the drawings, the device membrane has been segregated by a novel canopy structure into five circumferentially shaped segments  36   a  that are permitted to extend into five circumferentially spaced, irregularly shaped chambers  32 . As best seen in FIG. 2, each of the chambers  32  has a generally trapezoidal shape in cross section. As shown in FIG. 1, chambers  21  are separated by ribs  57  formed on cover  46 . With the construction thus described and as illustrated in the drawings, the membrane  36  in its second extended position shown in FIG. 6 will have an average percentage stress well in excess of the 50% average percentage stress of the membrane “M” shown in FIG.  6 A. 
     Referring particularly to FIGS. 2 and 3, the construction of an infusion means of the character described in the preceding paragraph, can be seen to include, in addition to the five chamber base and cover design, a downwardly extending hollow cannula  60  which is carried by a support member  62  that is received within a cavity  64  formed in base  16 . Support member  62  also functions to support flow control means for controlling the rate of fluid flow from chamber  31  toward hollow cannula  60 . This flow control means is here provided as a porous rate control frit  65  which can be constructed from a micro porous metal such as stainless steel. The frit can also be constructed from a porous ceramic or a porous plastic material. 
     Hollow cannula  60  has an inlet end  60   a  and an outlet end  60   b  formed in a needle-like segment that extends generally perpendicularly downward from the lower surface  24  of base  16 . To protect cannula  60  from damage, a protective cover assembly  67  surrounds the cannula. At time of use the sheath portion  67   a  of the cover assembly can be broken away from the base portion  16 . For this purpose, a serration line is preferably formed between the body of the sheath member and a connector collar  67   b  (FIG. 4) which functions to interconnect the cover assembly  67  with the base  16 . 
     Referring particularly to FIGS. 2 and 4, one form of the novel filling means of the present invention is there illustrated. As previously mentioned, the filling means functions to controllably fill the various chambers  32  with the medicinal fluid which is to be infused into the patient. In the present form of the invention, the filling means comprises a septum assembly, a filling syringe assembly and a novel fill adapter assembly. As best seen in FIG. 2, septum assembly  70  is sealably disposed within the previously identified fill port  34  which is formed in base  16 . Septum assembly  70  includes a septum housing  70   a  which is receivable within fill port  34  and an elastomeric pierceable core  70   b  that is sealably disposed within an opening formed in septum housing  70   a.    
     As best seen in FIGS. 2 and 4, the fill adapter of the invention, that is generally identified by the numeral  72 , is connected to connector collar  67   b . Fill adapter  72  includes an upper wall portion  72   a  and an enlarged diameter lower wall portion  72   b . Filling of the chambers  32  is accomplished using a conventional syringe having a cannula that is adapted to pierce core  70   b . It is to be understood that the septum can be a slit septum and the syringe can have a blunt-end cannula. 
     In using the apparatus of the invention, after chambers  32  have been appropriately filled using a conventional syringe, the fill adapter is broken away from flange connector collar  67   b  along serration lines formed therein. Next cannula protective sheath  67   a  is removed as is a foam-like protector  67   c  that surrounds needle  60 . This done, the device can be interconnected with the patient. This is accomplished by penetrating the patient&#39;s skin and tissue with the sharp point of the infusion cannula. During the infusion step, distended membrane  36  will urge the fluid contained within each of the chambers  31  and  32  to flow through flow passageways  75  formed in base  16  (FIG. 5) and into the inlet  60   a  of cannula  60  via the flow control means or rate control frit  65 . Because of the novel configuration of chambers  32  and the cooperating stored energy means, the ultra-low profile device of the invention is capable of delivering the medicinal fluid to the patient at a precise rate over an extended period of time. 
     Turning next to FIGS. 7 through 15, an alternate form of the invention is there shown and generally designated by the numeral  84 . This latter form of the invention, which is similar in some respects to the earlier described embodiment comprises a housing  85  that includes a base  86  having an upper surface  88  including a generally dome shaped central portion  90  and a peripheral portion  92  circumscribing central portion  90 . Base  86  also includes a lower surface  24  to which a patient interconnection means or adhesive pad  96  is connected. Pad  96  which comprises a foam tape having adhesive on both sides functions to releasably interconnect the device to the patient so as to hold it securely in place during the medicament delivery step. A peel-away member  96   a  covers a portion of the lower surface of the pad  96 . 
     As in the earlier described embodiment, a stored energy means cooperates with the upper surface  88  of base  86  and with uniquely configured cover means, or cover assembly  100 , to form a plurality of irregularly shaped fluid chambers  102  (FIG.  9 ). Base  86  has an inlet-outlet flow passageway  104  that communicates with a novel fill means for filling chambers  102  with the medicinal fluid to be infused into the patient. The stored energy means is once again provided in the form of at least one distendable membrane  106  that superimposed over base  86 . Membrane  106  is distendable from the first position shown in FIG.  9  to the second distended position as a result of pressure imparted on the membrane by fluids introduced into the uniquely configured chambers  102  via passageway  104 . As membrane  106  is distended into its second position where it extends into chambers  102 , internal stresses will be established, which stresses tend to move the membrane toward a less distended configuration and in a direction toward upper surface  88  of base  86 . As before membrane  106  can be constructed from a single membrane or from multiple membranes that are overlaid to form a laminate construction. 
     Provided within reservoir chambers  102  is ullage defining means for providing ullage within each of the chambers, which ullage means is engaged by membrane  106  as the membrane moves toward its less distended starting configuration. The ullage defining means here comprises the generally dome shaped, annular protuberance  110  formed on base  86 . Ullage  110  circumscribes generally dome shaped protuberance  90  so that when the distendable membrane, after being distended, tends to return toward its less distended configuration, fluid contained within the fluid chambers  102  will flow outwardly toward the infusion means of the invention. 
     Superimposed over base  86  is the previously mentioned cover means, or cover assembly  100 . Cover assembly  100  includes a rigid or semi-ridge cover portion  112  that functions, through the use of novel sealing means, to sealably enclose membrane  106  and a soft elastomer member  114  that overlays portion  112 . The sealing means here comprises a pair of generally circular grooves  118  formed in the peripheral portion of base  86  and a pair of cooperating, generally circular, annular shaped rim like protuberances  120  formed on the peripheral lower surface  112   b  of the cover  112 . Protuberances  120  are receivable within grooves  118  in the manner shown in FIG.  9  and function to sealably clamp distendable membrane  106  between the cover portion  112  and base  86  thus forming a bonded, hermetically sealed assemblage. As before, elastomer covering  114  forms the upper surface of the cover assembly and serves both to enclose chambers  102  and also to make the device more patient friendly. The same materials identified in connection with the embodiment of the invention shown in FIGS. 1 through 6 are suitable for use in the construction of the cover assembly  100 , the membrane  106  and the base  86 . 
     Considering next the novel fill means or fill assembly of the invention, this portion of the apparatus comprises a container subassembly  124 , and an adapter subassembly  126  (FIG.  15 ). As best seen in FIG. 10, a plunger  128  is telescopically movable within chamber  124   b  of container subassembly  124  between first and second locations. As shown in FIGS. 10 and 15, adapter subassembly  126  comprises a hollow housing  126   a  having a first open end  126   b  and a second closed end  126   c . The adapter subassembly  126  is telescopically receivable within an elongated receiving passageway  130  formed in housing  85  in the manner best seen in FIGS. 7,  9 , and  10  so that the adapter subassembly can be moved from a first extended position shown in FIGS. 7 and 15B into the second fluid dispensing position shown in FIG.  10 . Adapter subassembly  126  also includes pusher means shown here as an elongated pusher rod  132  that functions to move plunger  128  within the fluid chamber  124   b  of the container subassembly during the reservoir filling step. 
     As best seen in FIG. 9, disposed between the outer wall of container subassembly  124  and the inner wall of adapter  126  is a vial housing or receiving tube  134 . With this construction, during the mating of the reservoir fill assembly with the base assembly, the outer wall of adapter subassembly  126  is closely received within the receiving chamber  130  of the housing and as the adapter subassembly is urged inwardly or forwardly of the device housing, and the vial housing tube  134  is received within the adapter assembly  126 . It is to be observed that when the adapter assembly is originally mated with the device housing, the container subassembly  124  can be moved telescopically inwardly of vial housing tube  134  in a manner to move the vial septum  136   a  of a septum assembly  136 , which includes a septum clamping ring  136   b , into piercing engagement with a hollow cannula  140 . In this regard, it should be noted that hollow cannula  140  is supported by a needle housing  141  and extends inwardly into receiving chamber  130  in the manner illustrated in FIG.  10 . As best seen in FIGS. 9 and 15, a fill assembly cover  139 , which forms a part of the cover assembly  100 , covers the fill means. 
     Once the fluid flow path between the hollow cannula  140  and the fluid reservoir of the apparatus is created via passageways  142 ,  144  and  104  (FIGS. 8,  9 , and  12 ), an inward movement of the adapter subassembly can be accomplished by pushing on the closed end  126   c  thereof. As the adapter subassembly moves inwardly, pusher rod  132  will move plunger  128  forwardly of chamber  124   b . As plunger  128  is moved forwardly, fluid contained within vial chamber  124   b  will flow through hollow cannula  140 , into passageway  142  and finally into the fluid reservoir via passageways  144  and  104 . As indicated in FIGS. 8,  9 , and  15 , passageway  144  is uniquely formed in a generally “L” shaped fluid flow plate  147  that is carried within base  86 . 
     It is to be noted that adapter subassembly  126  is provided with a plurality of longitudinally spaced locking teeth  150  that slide under a resiliently deformable locking tab  152  during mating of the adapter subassembly with the device housing. Locking tab  152  is fixedly mounted on base  86  so that a leg  152   a  extends into receiving chamber  130  (FIG.  13 ). As the adapter subassembly is inserted into receiving chamber  130 , leg  152   a  will deflect and slide over teeth  150 . However, when the adapter subassembly is fully inserted as shown in FIG. 13, leg  152   a  will block removal of the adapter subassembly as well as the medicament vial of container subassembly  124 . 
     Also forming an important feature of this latest form of the invention is the infusion means for controllably infusing the beneficial agents contained within the device reservoir into the patient. The infusion means here comprises an elongated delivery line  156  that is connected to housing  141  and communicates with the outlet passageway  158  of the device (FIG. 10) and a conventional line clamp  160  (FIG.  7 A). Disposed between passageway  158  and line clamp  160  is a vent means shown here as a conventional gas vent and filter assembly  162  (FIG. 7A) which is also of the character previously described. 
     Also forming a part of the infusion means is a subcutaneous infusion needle assembly  164  that is connected to the distal end of delivery line  156 . Assembly  164  can be of a readily commercially available type or alternatively can be of the character illustrated and described in U.S. Pat. No. 5,858,005 issued to the present inventor. U.S. Pat. No. 5,858,005 is incorporated by reference as though fully set forth herein. Reference should be made to this patent for a description of the construction and operation of one possible form of assembly  164 . 
     Another feature of this latest form of the invention is the provision of flow rate control means for precisely controlling the rate of flow of the medicament to be infused from the device reservoir toward the infusion means described in the preceding paragraph. This rate control means here comprises a porous rate control frit  166  that is mounted within housing  85  between outlet passageway  158  (FIG. 10) that communicates with passageway  104  and delivery line  156 . Frit  166  can be constructed from various materials of varying porosity, including by way of example, stainless steel, ceramic and porous plastics. 
     Referring to FIGS. 7A and 7B, an alternate form of infusion means is there shown. This alternate embodiment includes rate control means provided in the form of an in line rate control capillary  165  having a coextended microbore  165   a  of a selected diameter (FIG. 7B) so as to precisely control the rate of fluid flow toward a luer connector  167  to which a needle assembly or the like can be connected. Rate control capillary  165  can be used separately or in series with rate control frit  166  to control the rate of fluid flow to the patient. 
     Still another important aspect of the apparatus of the invention is flow indicating means for visually indicating to the care giver that when clamp  160  is open fluid is flowing from the device reservoir toward the infusion means. In the present form of the invention this flow indicating means comprises a flow indicating assembly  170  that is disposed within housing  85  proximate receiving chamber  130 . More particularly, flow indicating assembly  170  is housed within a hollow chamber  172  that is formed within base  86  and cover  139  (FIG.  9 ), and comprises a generally cylindrically shaped member  174  having a first segment  174   a  of a first color and a second segment  174   b  of a second color. Member  174  is sealably movable within chamber  172  in response to fluid introduced into the chamber under pressure via a fluid passageway  180 . Biasing means, shown here as a coil spring  182 , yieldably resists this movement of member  174  within chamber  172 . In operation, when fluid is flowing from the reservoir of the device toward the infusion means via passageway  144 , a portion of the fluid will be diverted into passageway  180  and will flow into chamber  172 . When no fluid is flowing through passageway  180 , segment  174   a  is viewable through viewing port  178 . However, upon fluid flowing into chamber  172  via passageway  180 , segment  174   b  will became visible through viewing port  178 . For convenience, segment  174   a  may be colored red, while segment  174   b  may be colored green. Accordingly, when member  174  is displaced by fluid pressure flowing into passageway  180 , the caregiver will see the green colored segment  174   b  indicating that fluid is flowing outwardly of the device. When fluid flow outwardly of the device ceases, fluid flow through passageway  180  will also cease. With no fluid flowing into chamber  172 , spring  182  will urge member  174  into the starting position shown in FIG. 11 so that the red segment  174   a  is once again viewable through viewing port  178  thereby indicating to the caregiver that the device reservoir is empty. 
     Having now described the invention in detail in accordance with the requirements of the patent statues, 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 condition. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth in the following claims.