Buckles, Richard G. (Menlo Park, CA)
Hoff, Seymour (San Jose, CA)
Kehr, Sharon (San Jose, CA)
Yum, Su Il (Mountain View, CA)

05/439137

07/22/1975

02/04/1974

Download PDF 3895631       PDF help

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ALZA Corporation (Palo Alto, CA)

604/132

222/386.500, D24/111, 604/250

A61M5/152; A61M39/28; A61M5/145; A61M39/00; A61M5/14

128/214E,214F,213,215,216,230,260,DIG.12,DIG.13,214.2,214R,218A 222/95,105,106,206,212,23,47-49,386.5 138/40-44 251/5-9

3468308	PRESSURE INFUSION DEVICE FOR AMBULATORY PATIENTS WITH PRESSURE CONTROL MEANS	September 1969	Bierman
3469578	INFUSION DEVICE FOR AMBULATORY PATIENTS WITH FLOW CONTROL MEANS	September 1969	Bierman
3486539	LIQUID DISPENSING AND METERING ASSEMBLY	December 1969	Jacuzzi
3645298	COLLIMATED HOLE FLOW CONTROL DEVICE	February 1972	Roberts et al.
3717176	HYDRAULIC VALVE	February 1973	Smith
3731679	INFUSION SYSTEM	May 1973	Wilhelmson et al.

Medical-Surgical Review, "Ject-Ette," First Quarter, 1968, p. 27, 1281218,A..

Gaudet, Richard A.

Mcgowan J. C.

Ciotti, Thomas Sabatine Paul Mandell Edward E. L. L.

What is claimed is

1. A liquid storing and dispensing assembly comprising:

2. Assembly as recited in claim 1 wherein said flow control means comprises: a deformable tube, a plurality of parallel, linear elongate fibers coextensively disposed in said tube, and compressing means disposed about the tube and deforming, to variable degrees, the tube.

3. Apparatus as recited in claim 1 wherein said assembly has a concave lower surface and a convex upper surface, the curvature of the upper surface being greater than that of the lower surface such that said upper and lower surfaces meet along first and second opposite sides.

4. Apparatus as recited in claim 3 wherein said cartridge comprises an elongated generally rectangular shell, one elongated wall of which is convex and forms a part of said upper surface of said housing.

5. Apparatus as recited in claim 1 wherein said cartridge includes valve means at one end thereof connected with said repository for enabling delivery of fluid to the exterior of said cartridge, said valve means being normally closed, and wherein said inlet means cooperates with said valve means to open the same when said cartridge is engaged with said housing.

6. A fluid storage and dispensing assembly comprising, in combination:

7. Apparatus as recited in claim 6 further including flow indicator means in said first housing assembly, said indicator responsive to fluid flow downstream of said flow control means and having a first state when fluid is being dispensed and a second state when fluid flow ceases.

8. Apparatus as recited in claim 7 wherein said flow indicator means comprises: a chamber connected in said flow passage between said fluid control means and said outlet means, said chamber defining an opening in a wall thereof; a diaphragm sealed over said opening; and signal means responsive to flexure of said diaphragm to indicate the flow state of fluid in said passage.

9. Apparatus as recited in claim 8 wherein said signal means comprises an L-shaped lever pivotally mounted at the elbow thereof in said first housing assembly, and means biasing a first arm of said lever into engagement with said diaphragm.

10. Apparatus as recited in claim 9 wherein said first housing assembly defines an opening in an exterior wall thereof, and wherein a second arm of said lever is movable between a first position away from said opening when in said first state, and a second position immediately behind said opening when in said second state.

11. Apparatus for metered flow of fluid from a selfcontained supply, comprising:

12. Apparatus as recited in claim 11 wherein said flow metering means comprises: a flexible tube, a mass disposed within said tube and filling a portion of the space defined therein, and means about said tube to apply a compressive force thereagainst.

13. Apparatus as recited in claim 12 wherein said force applying means includes a force applying wedge mounted in said housing for movement towards and away from said flexible tube; and wherein said control means includes a control wedge cooperating with said force applying wedge and movable in a direction generally parallel to the axial direction of said tube.

14. Apparatus as recited in claim 13 wherein said control wedge carries a rack gear.

15. Apparatus as recited in claim 14 wherein said control wedge further carries a pointing arm; and wherein a flow rate scale is imprinted on said housing, said pointing arm cooperating with said flow rate scale to indicate the fluid flow rate established by said control means.

16. Apparatus as recited in claim 12 wherein said flow metering means further comprises: a by-pass tube connected in said flow passage in parallel with said flexible tube, means closing said by-pass tube to the flow of fluid therethrough, said means being movable to an open position by a second tool inserted through a second opening in the wall of said housing; said by-pass tube having a flow rate capacity greater than said flexible tube whereby rapid bleeding of air from the apparatus may be accomplished and by which rapid dispensing of liquid may be effected.

17. A fluid storage and dispensing assembly comprising; in combination:

18. A device for the continuous delivery of a controlled reproducible flow of liquid comprising, in combination:

19. Apparatus as recited in claim 18 wherein said support means has a pointing arm and wherein said shell has a volume scale imprinted thereon, said pointing arm and said scale cooperating to indicate the volume of fluid contained within said bladder.

20. Apparatus as recited in claim 18 wherein said bladder includes a valve member at the end connected with said opening in said shell, said valve member being urged to a closed position by fluid under pressure in said bladder.

21. Apparatus as recited in claim 20 wherein said bladder includes filter means at the end connected with said support means for passing air but not liquid out of said bladder whereby said bladder may be completely filled with liquid and voided of air by forcing such liquid into said bladder through said valve end.

22. A device for the continuous delivery of a controlled reproducible flow of a liquid drug to a patient comprising, in combination:

23. The device as recited in claim 22 wherein said main housing has an exterior wall generally conforming to the curvature of an extremity of the patient and includes means for attaching the housing to such extremity.

24. The device as recited in claim 22 wherein the liquid drug is a drug for intravascular, subcutaneous or intramuscular infusion, and the means for administering the drug to a patient comprises means for such infusion.

25. An infusion unit for the continuous delivery of a controlled reproducible flow of a liquid drug to a patient, comprising, in combination: a housing defining inlet and outlet port means and containing a liquid flow passageway extending between said inlet and outlet port means, said passageway including flow control means for precisely metering fluid flow therethrough, and a liquid drug supply cartridge removably engaged with said housing at said inlet port means and comprising:

26. A liquid drug supply cartridge for use in an assembly for the continuous delivery of a controlled reproducible flow of such liquid drug to a patient, having a housing defining inlet and outlet port means and containing a liquid flow passageway extending between said inlet and outlet port means, said passageway including flow control means for precisely metering fluid flow therethrough, means connected with said outlet port means for administering the liquid drug to the patient, said cartridge removably engageable with said housing at said inlet port means and comprising:

27. An infusion unit for the continuous delivery of a controlled reproducible flow of a liquid drug to a patient comprising, in combination:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to devices for the storage and dispensing of liquid, and more particularly, to an improved portable apparatus for delivery of precisely controlled amounts of a liquid drug to a patient.

2. Description of the Prior Art

Many diversified applications exist for systems in which a relatively small amount of liquid is stored and subsequently dispensed at a precisely metered rate. One such application, in the medical field, relates to the infusion of various liquids, including liquid drugs, at accurate, reproducible flow rates to a patient. The prior art is generally cognizant of such systems, as exemplified by U.S. Pat. No. 2,842,123 to Rundhaug, which shows a transfusion apparatus having a collapsible bag for the fluid to be dispensed and a pressure container in sealed relationship about the outside of the bag; U.S. Pat. No. 2,847,007 to Fox, which teaches the provision of a flexible fluid pouch within a resilient container for the storage of whole blood or plasma; U.S. Pat. No. 3,469,578 to Bierman, illustrating an infusion device having a spigot valve for ambulatory use; and U.S. Pat. No. 3,486,539 to Jacuzzi, which shows another dispensing device having a restricted outlet passage.

Such structures, while generally satisfactory, have proven to be disadvantageous in many material respects. For example, a number of these devices are functional, but only in very crude forms. Complexity in manufacture, awkward operation, and the aesthetically displeasing mechanical appearance of such devices has hindered even their limited acceptance in the marketplace. More importantly, devices heretofore available, when manufactured on a production-line basis, exhibit liquid discharge characteristics varying widely from device to device; varying as the liquid contents dispensed; and at very low flow-rates in the range of 0.1 to 10 cc's per hour, varying from one flow setting to another. These failings make such systems unsuitable for application where variable amounts of fluid are being passed, the amounts passed must be known with exactness, the fluid must be dispensed at a consistent rate, calibration after each flow adjustment is either impossible or inconvenient, and the displeasing appearance of an overly mechanical assemblage must be minimized.

Accordingly, the need has arisen for a much improved device for the storage and precise dispensing at reproducible low flow-rates of fluids. such as liquid drugs, especially in connection with medical applications such as the infusion of such drugs to a patient. Furthermore, such a need is particularly evident in those applications where certain drugs are preferably applied at a continuous, low rate over relatively long periods of time in dosage levels which would preclude application of such medications other than by direct local infusion to the affected area.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to store and accurately dispense various liquids at precisely metered low flow-rates.

The present invention has another object in the construction of an aesthetically pleasing, self-contained infusion unit for the ambulatory delivery of small amounts of liquid drug over a relatively extended period.

Another object of this invention is to house a removable fluid supply cartridge, a precise low flow-rate fluid metering assembly, and related indicators in a contiguous, self-contained assemblage.

A further object of the present invention is to construct a lightweight, portable infusion unit which is disposable and particularly well suited for ambulatory use.

The present invention is summarized in that an assembly for the controlled, reproducible flow of a liquid drug from a self-contained supply to a patient, includes a sectioned housing; a repository of liquid drug under pressure, removably disposed in a first section of the housing; a flow metering assembly in a second section of the housing; a fluid passage in the housing interconnecting the repository with the flow metering assembly; and a conduit connected with the flow metering assembly for directing metered amounts of the liquid drug exteriorly of the housing to the patient.

This invention is particularly advantageous over the prior art in that a supply of liquid drug may be comfortably carried by a patient and applied, by infusion, directly where needed; that an infusion unit providing precisely metered low flow-rates may be simply and economically manufactured by production line techniques; that medical accuracy may be obtained in an ambulatory self-contained assemblage which is unimposing and aesthetically pleasing; and that the unit can be calibrated to administer precise dosages, is simple to operate, and is designed to be disposable after use.

Other objects and advantages of the present invention will become apparent from the following description of a preferred embodiment when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of an intravascular infusion unit according to the present invention;

FIG. 2 is a top plan view, partially in section, of the infusion unit of FIG. 1;

FIG. 3 is a sectional view, partially in elevation, of a portion of the flow control assembly of the infusion unit of FIG. 1;

FIG. 4 is an exploded perspective view of the infusion unit of FIG. 1 with certain parts broken away and certain parts shown in section;

FIG. 5 is a bottom plan view of the infusion unit of FIG. 1;

FIG. 6 is an exploded perspective view of the fluid repository cartridge of the infusion unit of FIG. 1; and

FIG. 7 is a sectional view of a detail of the valve assembly of the cartridge of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, a preferred embodiment of an infusion unit in accordance with the present invention includes a main housing 10 having a generally rectangular support base 12 upon which are mounted the various subassemblies making up the completed apparatus. Support base 12 is preferably, slightly curved in order to accommodatingly conform to the curvature of either a particular portion of the torso of a patient or an extremity thereof, such as an arm or leg.

The embodiment illustrated herein is particularly well suited for use on the arm or leg of a patient, and in order to maintain the infusion unit in position upon such extremity, any of various suitable attaching mechanisms, assemblies or devices may be employed, such as a pair of adjustable elastic bands 14 and 16 affixed to the underside of the base 12 as shown in FIG. 1. While only support straps have been illustrated herein for the sake of brevity, it should be understood that any appropriate technique may be used to attach the infusion unit of the present invention to the patient. Exemplary devices are synthetic or metallic clips or bracelets; suitable belts or straps provided with cloth fasteners, zippers, buckles or the like; or elastic or inelastic ties or adhesive tapes.

Mounted atop support base 12 are first and second spaced, elongated compartments or housing sections 18 and 20 each having a generally triangular cross-section as can best be visualized in FIGS. 1 and 4. Compartment 20 is defined by a generally flat, upright interior wall 22, an outwardly and downwardly angulated floor 24, and a generally flat angularly inclined outer wall 26. The end of compartment 20, to the left as visualized in FIG. 1, is closed by a triangularly shaped wall 28 which is contiguous at its periphery with walls 22, 26 and the support base member 12. The opposite end of compartment 20 is spaced from the right edge of support base 12 and is open to enable communication between compartment 18 and a generally rectangular slot or recess disposed between housings 18 and 20.

Compartment 18 has along its inner side a generally upright wall 30, which extends from support base 12 to the upper edge of a flat, inclined outer wall 32 which joins base 12 along its longitudinal edge. The left end of housing or compartment 18, as visualized in FIGS. 1 and 4, is closed by a triangular, upright wall 34, with the opposite end of the compartment 18 open and recessed from the edge of support base 12 in a manner similar to that of housing or compartment 20. A convex wall 36 of generally triangular configuration has a smoothly rounded inwardly directed flange formed about the upper periphery thereof and closes the right end of the assembly by joining walls 26 and 32 with the support base 12.

A locking lever 40 is journalled at an end 42 for pivotal rotation about a pin 44 protruding inwardly from upright wall 30 of compartment 18. End 42 further supports a flange 46 for cooperative engagement with a protrusion (not shown) on wall 30 so as to delimit the degree of upward swing of arm 40 away from the support base 12. The other end 48 of lever 40 carries a downwardly extending generally flat plate 50. A locking tang 58 protrudes laterally below the bottom edge of plate 50 for cooperative engagement with an aperture 60 (FIG. 5) defined in the support base 12 of the infusion unit 10. Arm 40 also carries a generally triangular, curved outer wall 62 which acts as a handle and is shaped such that the lever 40, when in the closed or locked position, is contiguous at its outer surface boundaries with the outer surfaces of compartment 18 of the infusion unit.

Referring now to FIG. 4, the floor 24 of compartment 20 carries a plurality of protrusions which cooperate with the various components of the flow control system of the present invention shown in detail in FIG. 3 and also in FIGS. 2 and 4. Leading to the flow control system is a first, generally U-shaped flow passage 70 which terminates at one end in a needle or pin-like protrusion 72 having a hole 74 therethrough communicating with a small, generally cylindrical interior chamber 76. Spaced from the front wall of chamber 76 by a suitable O-ring 78 is a filter assembly 80 consisting of one or more filters designed to trap or retain small particles or sediment and bacteria and preclude the passage of the same through the downstream portions of the flow control assembly to be described more fully below.

Downstream of filter assembly 80 is a flow passage 82 defined by a groove in the outer wall of element 70 and a suitable flat plate 84 attached thereover. Passage 82 continues through an elbow 86 in member 70 and is outwardly divergent to provide a second interior chamber 88. At this point it is noted that element 70 is constructed so as to join with base 12, the edge of end piece 36, and upstanding walls 22 and 30 at the right ends of compartments 18 and 20. In this manner, member 70 functions as an end wall of the generally rectangular slot or void 90 atop base 12 between chambers 18 and 20 and closes off the compartment joining compartments 18 and 20 of the overall housing.

Chamber 88 in elbow 86 has a first outlet port 92 and a second, smaller outlet port 94 disposed side-by-side in a wall 96. Ports 92 and 94 protrude slightly from the outer surface of wall 96 and have attached thereto, in sealed relationship, first and second flexible fluid carrying conduits 98 and 100, respectively. As shown in FIG. 4, a generally rectangular upstanding block 102 is formed in the floor 24 of compartment 20 and has longitudinally aligned thereupon a pair of upstanding dividing walls 104 and 106. Walls 104 and 106 are spaced from each other such that the slot defined therebetween will accommodate flexible conduit 100, with larger flexible conduit 98 disposed on the other side of wall 106.

Conduits 98 and 100 terminate at their opposite ends in a connecting block 108 having inlet ports 110 and 112 similar to ports 92 and 94, respectively, and accommodating the ends of flexible conduits 98 and 100 in a fluid-tight manner. Connector block 108 is preferably rectangular in configuration, but may be of any suitable external shape as desired. As shown, block 108 has a groove running completely thereabout for firm engagement with a generally U-shaped upstanding protrusion 114 in the floor 24 of compartment 20.

Interiorly of block 108, a chamber 116 provides communication between ports 110 and 112 and an outlet port 118 for connection through the floor of compartment 20 with a flexible surgical tube 120. The end of tube or conduit 120 is suitably connected with a catheter or needle for intravascular infusion of fluids to a patient in the conventional manner. Disposed interiorly of conduit 98 are a plurality of elongate fibers 122 which coextensively are nested in a close relationship and fill a substantial portion of the cross-sectional volume of the conduit 98.

A spring element 124 (FIG. 2) is held at its proximal end in a recess 126 formed adjacent elbow 86 in the floor 24 of compartment 20 and has, at its distal end, an offset, curved portion adapted to engage flexible conduit 100. Spring 124, when disposed in recess 126 exerts a biasing force against the flexible conduit 100 so as to pinch or crimp the same between the curved offset portion thereof and the side of upstanding wall 106. In this manner, spring 124 normally precludes the passage of fluid through conduit 100 and enables fluid flow therethrough only when the spring is lifted away from wall 106.

A first generally triangular wedge member 128 is mounted on the opposite side of flexible conduit 98 from wall 106 and is slidable laterally into engagement with such conduit in a path defined by stops 130 and 132 in the floor of compartment 20. A control wedge 134 is disposed adjacent wedge 128 such that longitudinal movement of the control wedge 134 urges wedge 128 into engagement with flexible conduit 98 which is thereafter compressively entrapped between the wedge 128 and upstanding wall 106, the floor of block 102 and the wall 26. Such compressive force distorts the configuration of the conduit 98 such that the area therein decreases resulting in the elongated fibers 122 taking up more of the available space within the conduit for fluid flow. At the left end of control wedge 134, as visualized in FIG. 2, a rack gear 136 is provided having a guide prong 138 protruding from the end thereof so as to slidably engage the front corner of compartment 20. A pointing arm 140 extends from the end of rack gear 136 in a direction opposite to the projection 138 and has a scribed line thereon for cooperation with a flow-rate scale 144 carried upon the outside of wall 26 (FIG. 1). Pointer 140 can be seen through an opening 146 in wall 26 and, since the longitudinal position of rack 136 determines the lateral position of wedge 128, indicates the flow-rate of fluid being dispensed through the infusion unit according to the present invention.

A second aperture 148 is defined by the wall 26 of compartment 20 for admitting a first end of a tool 150 having a pinion gear 152 formed thereon for cooperative interengagement with the gear teeth of rack 136. As can be appreciated from FIG. 1, tool 150 may easily be inserted through aperture 148 and rotated so as to longitudinally move the control wedge 134 for regulating the force applied through wedge 128 to the fiber containing conduit 98. The flow-rate thus established is accurately maintained and is precisely indicated by the position of pointer 140 with respect to scale 144.

Chamber 116 in connector block 108 defines a hole or opening 158 in the wall thereof opposite ports 110 and 112, which hole is closed by a flexible diaphragm 160 sealed by a suitable annular clamp 162. Diaphragm 160 thus moves in response to the pressure built up within the system located between the flow control element 110 and the outlet tubing 120. An L-shaped indicator arm 164 is pivotally mounted to the floor 24 of compartment 20 and has a first leg 166 engageable with and responsive to movement of diaphragm 160 of the connector block 108. The other leg 168 of lever 164 carries a flag or signal 170 at its distal end. Signal 170 may be painted with a bright color or provided with any other suitable indicia and has its arcuate path of travel aligned so as to bisect an aperture 172 in wall 26 of compartment 20. In addition, a small biasing spring 174 is torsionally wound about the axis of arm 164 between leg 168 and a stop 176 in the floor of compartment 20.

In this manner, arm 164 is gently biased such that leg 166 engages the diaphragm 160, with leg 168 carrying signal 170 to a nested position hidden behind wall 26 away from aperture 172. Should the fluid flowing through the system to the catheter or needle become blocked for some reason, the pressure of the fluid supply causes diaphragm 160 to bulge outwardly from connector block 108 thereby rotating arm 164 and transposing signal 170 to a position immediately behind aperture 172. The visual perception of signal 170 through aperture 172 thereafter apprises the patient or his attending physician or nurse that infusion has ceased.

A plurality of grooves such as orthogonal grooves 180, 182 and 184 are formed in the undersurface of support base 12 in order to allow fluid conduit 120 to be guided along the bottom of base 12 and brought out to the front, rear or side of the infusion unit for ultimate connection to the catheter at the end of the tube in the most convenient manner. Of course, it should be understood that any number of grooves may be provided in the undersurface of support base 12 and that the three grooves shown in FIG. 5 are merely exemplary of such structures.

A cartridge assembly 200 formed of left and right cartridge halves 202 and 204, respectively, has a generally rectangular overall configuration conforming to the void or slot 90 defined above base 12 between compartments 18 and 20. Further, the upper surfaces of sections 202 and 204 are slightly curved such that when the cartridge is slidably engaged with the support base and housings, and arm 40 is pivotally moved to its locked position, the overall assembly has a smooth contiguous outer surface as shown in FIG. 1. Portion 204 of cartridge 200 has a first end wall 206 defining an aperture 208 therein. Aligned over aperture 208 is a valve assembly 210 of a distensible fluid containing bladder or repository 212. Valve assembly 210 is attached to wall 206 in any suitable manner such as by means of clamps, bolts, interlocking grooves, etc.

The heart of the valve assembly 210 is a flat, resilient member 214 having a pair of frustoconical apertures 215, which, as shown in FIG. 7 in solid lines is urged by the internal pressure within the bladder into a closed position in sealed engagement with wall 206 of the cartridge assembly 200. Of course, it should be understood that any suitable valve assembly may be incorporated into the bladder 212 and, in the alternative, valve 210 may be replaced with a simple flap valve or flexible seal adapted to be punctured by a needle for admitting or dispensing fluid. Such modification would be accomplished with like modification of projection 72 or substitution of a sharp needle therefor.

The opposite end of bladder 212 defines an opening 216 having an annular flange 218 formed thereabout. Aligned over opening 216 against the surface of flange 218 is a microfilter element 220 which allows the passage of air therethrough but not fluid. Such microfilters may be formed of any well-known, commercially available materials and thus will not be described in detail for the sake of brevity.

Element 220 is firmly clamped between flange 218 and the inner flat surface of a sliding element or spider 222 having a plurality of arms 224 extending radially from a central hub thereof. Arms 224 are preferably engaged with the four inner corners of the rectangular shell provided by portions 202 and 204 of cartridge 200 such that the spider is freely slidable longitudinally within the compartment. An aperture 226 extends completely through the central hub of the sliding element 222 such that air passing through filter 220 may be expelled to the atmosphere. A generally L-shaped indicating arm 228 protrudes upwardly from the central hub of member 222 and has a first leg which extends over a recessed path 230 longitudinally disposed along a central portion of portion 204. A suitable volume scale 232 is imprinted upon the upper surface of portion 204 and cooperates with indicator arm 228 to enable easy perception of the volume contents of the bladder or repository 212.

As described in detail in copending application Ser. No. 344,713, assigned to the assignee of the present application, bladder 212 may be distended by the admission of fluid under pressure through valve 210 such that the bladder is axially and radially enlarged, as shown in FIG. 2, for storing the liquid under pressure. As the liquid drug is forced into the bladder 212, the same becomes axially elongated such that slider 222 moves toward the end away from the valve 210 indicating a volumetric change by the cooperation of indicating pointer 228 and scale 232. In addition, since the fluid repository 212 is supported between the valve assembly 210 attached with wall 206 of the compartment or cartridge 200 and the central hub of slider 222, the same is maintained at all times in spaced relationship with the inner walls of the compartment to allow precise delivery of the entire contents of the bladder with minimal frictional interference. Furthermore, the distensible elastic walls of the bladder 212 are constructed of a material having a characteristic enabling distention of the walls to approximately the inner dimensions of the cartridge 200 such that the bladder, even when fully distended, does not engage the inner walls of the cartridge.

A pair of pins 240 and 241, protrude laterally from the ends of a side wall of portion 202 of cartridge 200 for cooperative engagement with the inner edge of plate 50 and flange 46, respectively. Thus, as the cartridge 200 is slidably moved into position along the support base 12 (FIG. 4), pin 241 engages flange 46 and as arm 40 is rotated downwardly, pin 240 slides along said inner edge to firmly urge the cartridge into a nested position with the pin or nozzle end 72 of the housing fluid passage inserted through aperture 208 and into engagement with the member 214 of valve assembly 210.

In operation, a particular liquid drug intended to be administred by infusion to a patient is first forced into the distensible bladder 212 through valve assembly 210. An appropriate fitting may be formed on the valve end of the cartridge 200 for cooperation with a supply capsule such that the liquid drug supply may be affixed to the cartridge 200 with a needle-like member engaging member 214 of the valve assembly to open the same for the admission of fluid. Such fluid, under pressure, is then forced into the bladder causing the same to be radially and axially expanded or distended to a capacity of from about 20 cc to 100 cc. While such fluid is being forced into the bladder 212, slider 222 will be moved axially toward the end opposite valve assembly 210, indicating the volumetric capacity of fluid by the relative position of pointer arm 228 with respect to volume scale 232.

After bladder 212 has been completely filled, the liquid drug source is removed from the cartridge allowing member 214 to become firmly seated against wall 206 of the cartridge 200. The cartridge is then in a condition for subsequent use and may be stored under appropriate conditions or immediately inserted into the housing assembly for use. It should also be noted that during the filling operation, microfilter 220 allows any air initially contained within the deflated bladder 212 to pass through aperture 226 in the slider 222 for assuring complete filling of the repository with the liquid drug to be dispensed. By tilting the cartridge assembly such that the end opposite valve assembly 210 is in an elevated position relative to such valve assembly, the air trapped within the bladder 212 will rise to the top and will be slowly released through filter 220 to the atmosphere. As noted above, mocrofilter 220 may be of any suitable type, such as that sold under the name "Cellguard", and enables the passage of air but yet precludes the flow of the liquid drug out of the repository 212, thereby enabling rapid bleeding of the cartridge assembly so that it will be filled only with the liquid drug.

Once the cartridge assembly has been completely filled with liquid drug, and it is desired to administer the same to a patient, the cartridge may be properly positioned in the void or slot 90 formed by the spaced positioning of compartments 18 and 20 atop support base 12. Preferably, cartridge assembly 200 is positioned at the left end of the slot 90, with locking arm 40 in approximately the position illustrated in FIG. 4. The cartridge is then gently slid to the right, the same being properly guided or aligned between upstanding walls 22 and 30. As shown in FIGS. 2 and 7, as the cartridge moves toward the right end of the housing assembly, the projecting pin 72 of end member 70 first passes through aperture 208 in the right wall 206 of the cartridge assembly and, as the cartridge is further advanced, engages member 214 so as to deformingly urge the same to its open position (illustrated in phantom in FIG. 7) thereby permitting liquid to flow through apertures 215 and slots or openings in the leading end of pin 72 (not shown) and thus into hole 74.

At this same time, lever arm 40 must be moved downwardly toward its locking position. This action causes pin 240 to slide along the inner edge of plate 50 further urging the cartridge assembly 200 into its properly nested position atop the support base 12. After the cartridge assembly is fully seated to the right as shown in FIG. 2, locking arm 40 may be further moved such that the locking tang 58 engages the shoulder of rectangular opening 60 in the base 12 and firmly locks the cartridge in place. As can be appreciated from FIG. 1, when the cartridge assembly 200 is positioned atop support base 12, and lever arm 40 is rotated down into its locked position, the housing has a smooth, continuous exterior surface whereby the assembly resembles a unitary structure.

With the cartridge in position atop the housing, the cooperative interaction of pin 72 and member 214 causes the establishment of communication between the liquid drug contents of the repository 212 and the fluid passageway 82 formed in the right end of the housing assembly. Such fluid is then enabled to flow through aperture 74 and into chamber 76 where it must pass through the filter assembly 80 thereby assuring the removal of any bacteria, sediment or other small particles which may have inadvertently entered the system. While the liquid drugs which might be expected to be used in connection with the apparatus according to the present invention will not normally contain any particulate matter, the filter assembly 80 assures the complete removal of all particles thereby guaranteeing the positive metering of fluid through the fluid flow control to be described below.

The fluid passage 82 opens into chamber 88 which feeds both the main flexible conduit 98 and the smaller secondary conduit 100. These two conduits form parallel paths for the flow of fluid through the system with the main branch providing precise and accurate metering of fluid during normal operation and the smaller conduit 100 enabling rapid bypass or bleeding of the system during selected times. The controlled flow through the parallel circuit of flexible conduits 98 and 100 passes through connector block 108 from whence it is delivered through tube 120 for intravascular infusion. While the particular details of the entire tube assembly 120 have not been shown, it should be understood that any well-known surgically approved technique may be utilized whereby the tube 120 terminates in an I.V. catheter or needle for insertion into the patient for administration of the drug or in a standard connector for connection to a catheter or needle.

As described above, a spring member 124 (FIG. 2) has an offset, curved distal and portion which is normally biased into engagement with flexible conduit 100 so as to pinch the same against upstanding wall 106 thereby closing the conduit to the passage of fluid from repository 212. Since the primary flow through conduit 98 is a low-rate flow, it would take considerable time to bleed any air from the system when initially preparing the apparatus for use. Thus, spring member 124 is provided for cooperation with bypass conduit 100 such that as the spring 124 is moved away from the conduit, a secondary flow is enabled through conduit 100 so as to rapidly purge the system of any air. Thereafter, spring 124 may be released whereupon the bypass conduit 100 is again closed-off enabling the fluid flow to again be precisely metered through primary conduit 98. As shown in FIG. 1, a generally rectangular opening may be provided in the wall 26 of compartment 20 to enable a flat blade of tool 150 to be inserted into the compartment 20 for the selective flexure of spring 124 away from conduit 100.

Conduit 98 contains a plurality of coextensively disposed elongated fibers 122 which, as shown, substantially fill the conduit and are parallel to each other within the conduit 98. Fibers 122 are essentially linear and are made of a resilient elastomeric material, such as, for example, the poly(urethane) sold under the name "Lycra Spandex", silicone rubber, polyisoprene and butyl rubber. Since conduit 98 rests in position atop block 102 between upstanding wall 106 and and a flat side of wedge member 128, a compressive force is applied to the conduit in a direction which is perpendicular to the flow of fluid therethrough. This compressive force is applied to the conduit at the point where the axially aligned fibers 122 are disposed, and may be applied over all or part of the length of the aligned fibers.

As a compressive force is applied against conduit 98 by the wedge 128, the conduit is selectively caused to be deformed. Since the circumference of conduit 98 does not change appreciably, this deformation brings about a decrease in the conduit's cross-sectional area. The cross-sectional area of the aligned fibers, however, does not change appreciably so that as the conduit 98 is compressed, the proportion of the space within the conduit taken up by the fibers is changed to enable precise metering of fluid flow therethrough. The internally aligned fibers are closely packed within the conduit and generally should take up at least 50 percent of the internal cross-sectional area of the conduit prior to compression. Preferably, the fibers are themselves of rounded or cicular cross-section such that they align themselves in a close-packed, nested configuration. The number of such internal fibers and their size relative to the diameter of the conduit's inside diameter may vary. As a general rule, there must be at least about six internal fibers and the upper limit, which is not critical, may be as much as several hundred fibers.

In order to precisely control the flow-rate through the conduit 98, control wedge 134 is disposed in compartment 20 and coacts with wedge 128 such that the longitudinal position of control wedge 134 causes very slight movements of wedge 128 perpendicular to the conduit. In this manner, compressive forces of greater and lesser magnitude are simply, effectively, and reproducibly generated and applied by wedge 128 to the conduit 98. The control wedge 134 carries a rack gear 136 which, as noted above, is accessible through aperture 148 in the outer wall 26 of compartment 20. Pinion gear 152 of tool 150 may be easily inserted through aperture 148 so as to engage the rack gear 136 whereupon rotation of the tool accurately and precisely positions the control wedge 134.

Since the position of the control wedge 134 is determinative of the compressive force applied to conduit 98, and thus, the flow-rate established from the system, the position of pointer arm 140 relative to scale 144 enables the simple and precise visual perception of the preselected flow-rate of the system. Once the particular flow-rate desired has been established, tool 150 may be removed so as to preclude inadvertent adjustment or regulation of the flow-rate setting during use of the system. Of course, by subsequent reinsertion of the pinion gear 152 of tool 150 the system flow-rate may be reset as desired.

Conduits 98 and 100, fibers 122, and the distensible bladder 212 may be formed of the same material or of different materials. While any number of suitable materials may be utilized, certain exemplary materials are those which are resilient, deformable and are inert to the fluid or liquid drug stored and administered by the system. Exemplary materials include natural rubber (preferably suitably extracted or treated to remove impurities which potentially would contaminate the fluid), as well as synthetic elastomers, for example, poly(isoprene), poly(1,4-butadiene), segmented polyurethane of the poly-ether variety, block co- or ter-polymers containing butadiene and styrene, silicone rubbers such as the silastics, butyl rubber, nitrile/butadiene rubber and neoprene.

The present invention is further provided with a flow indicator so as to apprise the user of the cessation of fluid delivery from the system. Diaphragm 160 secured over opening 158 in the connector block 108 responds to the pressure of fluid within the system and causes a proportionate movement of the pivotally mounted arm 164 in accordance with such pressure changes. Normally, as fluid is dispensed through the system, the fluid pressure within connector block 108 is relatively low such that arm 164 is permitted to be rotated clockwise by spring 174, thereby carrying the signal 170 to a nested position away from aperture 172 in the outer wall of the compartment 20. If, for any reason, a blockage should occur downstream of the connector 108, the pressure within the entire system would quite rapidly build up to the internal pressure of fluid within the dispensing bladder 212 whereupon diaphragm 160 would respond by bulging slightly outwardly against leg 166 of indicator arm 164. As a result, arm 164 is rotated counterclockwise thereby carrying signal 170 through an arc whereby it becomes positioned immediately behind opening 172. The visual perception of signal 170 through opening 172 thereby signals the patient, his attending physician, or nurse that the delivery of the liquid drug has ceased and is no longer being accomplished. Accordingly, the appropriate steps may be taken to remedy the situation and once again commence the precisely metered delivery of the liquid drug by infusion.

Referring to FIG. 1, it should be appreciated that the present invention is preferably designed to be worn or attached to a portion of the torso or an extremity of a patient and is particularly well suited in connection with the direct administration of liquid drugs which must be applied in very slow rates over an extended period of time directly to a particular site of disease, infection, or the like. For example, in certain cancer chemotherapy, it may be desirable to apply a particular liquid drug directly to the forearm of a patient where a detected cancer nucleus has formed. In this case, the infusion unit can, according to the present invention, be attached to the patient either on the upper arm or forearm with the slight curvature of the lower surface of the support base 12 generally conforming to the curvature of such extremity portion. Straps 14 and 16 may be then adjusted so that the infusion unit is comfortably held in position about the arm of the patient.

The surgical tube 120 may then be positioned within one of the orthogonal grooves 180, 182 or 184 along the bottom of base 12 and brought out from that side of the infusion unit closest to the selected point of insertion of the I.V. catheter. Desirably tube 120 is of the nonclosure type, that is, its passageway is of a generally triangular cross-section which prevents it from being easily pinched off. Preferably, before the infusion unit is attached or fitted to the patient, a cartridge 200 which has been previously filled with the desired drug to be administered is slid onto the support base 12 in the manner described above. Thereafter, the blade end of tool 150 may be inserted through the opening in the housing wall to lift spring 124 away from bypass tube 100 causing the relatively rapid emission of fluid from the repository 212 through the passageways inside the infusion unit and thence through tube 120 and the catheter so as to discharge all of the air present within the system. Spring 124 is thereafter released closing off the bypass passage and allowing the desired, precisely metered flow-rate to be established by the primary fluid conduit 98 and its contained fibers 122.

The catheter is then inserted into the selected tissue or vascular passage associated with the disease site to be treated, and the precise, desired flow-rate is preset by insertion and rotation of tool 150 through opening 148. The positioning of control wedge 134 is thus easily selected and may be observed by comparison of pointer 140 with scale 144. The device will then continuously administer the precisely metered low flow-rate of liquid drug to the patient.

The infusion unit according to this invention is preferably constructed of molded plastic so as to be extremely lightweight and economical to fabricate. Such molding may be accomplished in accordance with any well-known techniques and, as such, may be fabricated from a number of individually molded pieces conventionally attached to form the overall apparatus. In this manner, the entire assembly may be sufficiently economically manufactured so as to be disposable after a single or a predetermined limited number of uses.

It can therefore be appreciated that the present invention provides a number of material advantages over devices heretofore available and allows precisely reproducible metered flow-rates of liquid drugs to be administered to a patient by infusion by apparatus which is economical, simple, aesthetically pleasing, and allows the patient to be at all times ambulatory while undergoing treatment. Further, the infusion unit according to the present invention may easily accommodate any number of replaceable cartridges containing the same or different liquid drugs for administration to a patient at various times, each cartridge being refillable or disposable after such patient has completed the intended treatment.

Inasmuch as the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.