IE42702B1 - Liquid infusion unit - Google Patents

Abstract

1484394 Infusion apparatus ALZA CORP 17 Jan 1975 [4 Feb 1974] 2137/75 Heading A5R [Also in Divisions Fl and F2] A liquid infusion unit for continuous infusion of liquid drugs into a patient at a controlled rate comprises a housing 10 which is attachable to the patient by straps 14, 16 and which has a recess 90 on the side facing away from the patient; a cartridge assembly 200 for containing the liquid under pressure and which removably fits within said recess; a liquid flow path enclosed within the housing and which connects with the liquid outlet of said cartridge; an adjustable flow controller in said housing for regulating the flow rate in said flow path; and a conduit leading from the flow path to the infusion site. The unit has a generally crescent shaped transverse cross section having a concave support base 12 for engaging the patient and a convex upper surface. The flow path comprises a hollow needle 72 which is mounted on an element 70 having a cylindrical interior chamber 76 in communication with the hole 74 in the needle. A filter 80 is mounted in the chamber 76. A passageway 82 leads to two flexible parallel conduits 98 and 100 which lead to a chamber in a connecting block 108 having an outlet. Conduit 100 is closed by a spring 124 and may be opened by a tool 150 for bleeding the unit prior to use. Conduit 98 contains a plurality of longitudinally extending fibers. A wedge 128 is transversely slidably mounted between stops 130 and 132 and is acted on by a longitudinally movable control wedge 134 to squash conduit 98 between a wall 106 and wedge 128 to thus reduce the cross-sectional area inside conduit 98 and thereby control the flow of liquid. A rack gear 136 is provided on the control wedge, and this is operated by a pinion 152 on tool 150 which may be inserted through a hole 148 in the housing. A pointing arm 140 is provided to correspond with a scale 144 along the edge of an opening 146 in the housing. A flexible diaphragm is provided in the flow passage and this operates an indicator arm 164 having a flag 170 which may be seen through a aperture 172 in the housing to signal excess pressure in the event of a flow blockage downstream of the outlet. The cartridge 200 comprises outer shell halves housing a distendable bladder 212. The cartridge has a valve assembly 210 comprising a resilient member 214 having apertures and an end wall having a central aperture such that insertion of needle 72 through said aperture distends the resilient member allowing flow communication from the bladder via said apertures. The bladder has a gas permeable microfilter 220 which allows venting of gas during filling. A spider attached to the bladder has an indicating arm 228 which corresponds with a scale 232 on the outside of the cartridge. A locking lever 40 engages pins on the cartridge to hold it firmly in position.

Description

The present invention relates to liquid infusion devices.

Many uses exist for devices that can dispense a small amount of liquid at a precisely metered rate. One such use is the infusion of t various liquids, including liquid drugs, oi accurate, reproducible j I'low rater, to a patii-nt. The prior art is generaI ly rugnir.arit of such device:;, as exemplified hy li.i!. Patent Mo. 2,842, 1 ·''> to Ruudhaug that shows a transfusion apparatus having a collapsible hag for the fluid and a pressure container in sealed relationship about the outside of the bag; U.S. Patent Mo. 2,847,007 to Fox that discloses a flexible fluid pouch LO within a resilient container for storing whole blood or plasma; U.S, Patent Ho. 3,469,578 to Wennan that illustrates an infusion device having a spigot valve for ambulatory use; and U.S. Patent Ho. 3,486,539 to Jacuzzi, that shows a liquid dispensing device having a restricted outlet passage. .5 Such devices, while capable of performing their primary function have nevt?ri.lieles:: proven to be disadvantageous in many respects. For example, a number of these devices are functional, but only in very crude forms. Complexity in manufacture, awkward operation, and tho aesthetically displeasing mechanical appearance of such devices have LO hindered even their limited acceptance in the marketplace. More important, devices heretofore available, when manufactured on a production-line basis, exhibit liquid discharge characteristics varying widely from ς device to device; varying as the liquid contents are dispensed; and at very low flow rates in the range of 0.1 to 10 cc per hour varying significantly from one flow setting to another. These failings make such devices unsuitable for uses where variable amounts of fluid are being passed, the amounts passed must be known with accuracy, the fluid must he 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 he minimized. - 2 48702 Accordingly, the need has arisen for a inucri improved device for the storage and precise dispensing at reproducible low flow rates of fluids, ouch as liquid drugs, especially in connection with me-dical applications such as the infusion of such drugs io a patient. Further5 more, 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.

JO According to the present invention, therefore, th"rf. is provided a liquid infusion unit for infusing liquid drug -on tinuously into a patient at a controlled rate characterized by: (a) an elongate housing having means for attachment to the patient and having a recess on its exterior surface; (b) a liquid drug flow passageway enclos· d within the housing and having an inlet and an outlet; (c) a cartridge for containing liquid drug under pressure that removably fits in the recess on the exterior surface of the housing such that the unit has a smooth, contiguous exterior surface, the Ρ0 cartridge having an outlet for the liquid drug that connects with the inlet of (b) when the cartridge is fitted in the recess; (d) a flow controller associated with (b) between the inlet and outlet of (b) that regulates precisely the flow rate* of liquid drug through (b); and (e) a conduit connected to the outlet of (b) that extends to the infusion site.

As used herein and in the claims, the te.m liquid drug includes drugs that are liquid in their natural form, solutions of drugs and other liquid formulations of drugs.

Following is a description by way of example only with reference to the accompanying drawings of an infusion unit in accordance with the present invention.

In the drawings;Figure 1 is a perspective view of a preferred embodiment of an intravascular infusion Unit of the present invention; Figure 2 is a top plan view, partially in section, of the infusion unit of Figure 1; Figure 3 is a sectional view, partially in elevation, of a portion of a flow control assembly of the infusion unit of Figure 1; Figure 4 is an exploded perspective view of the infusion unit of Figure 1 with certain parts broken away and certain parts shown in section; Figure 5 is a bottom plan view of the infusion unit of Figure 1; Figure 6 is an exploded perspective view of a fluid repository cartridge of the infusion unit of Figure 1; and Figure 7 is a sectional view of a detail of a valve assembly of the cartridge of Figure 6.

Deferring to Figure 1, the infusion unit of the invention has a main housing 10 and a generally rectangular support base 12 upon which are mounted the various subassemblies comprising the complete unit. Support base 12 is preferably slightly curved to conform to the curvature of either a particular portion of the torso of a patient or an extremity such as an arm or a leg.

The illustrated unit is particularly well suited for use on tlie arm or leg of a patient, and in order to maintain the infusion unit in position thereon, any of various suitable attaching mechanisms, assemblies or devices may be employed, such as a pair of adjustable elastic straps 14 and 16 affixed to the underside of the base 12. - 4 43702 Alternative devices t,o straps 14, 16 are synthetic or metallic clips or bracelets; suitable belts or straps provided with cloth fasteners, zippers or buckles; or elastic or inelastic ties or adhesive tapes.

Mounted on support base 12 are two spaced, elongated compartments or housing sections 18 and 20 each having a generally triangular lateral crocs section as shown in figures 1 and 4.

Compartment 20 is defined by a generally flat, upstanding interior wall 22, a laterally outwardly and downwardly inclined floor ?4, arid a generally flat inclined outer wall 26. The end of compartment , t.o the left as seen in figure 1, is closed by a triangularlyshaped wall 28 that is contiguous at its periphery with walls 22, and the support base 12.

Compartment 18 has along its inner side a generally upright wall 30 that extends from support base 12 to tire upper edge of a flat, inclined outer wall 32 that joins base 1? along its lower longitudinal edge, l'he left end of compartment 10, as seen in Figures 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 b^se 12. A wall 36 of generally triangular configuration has a smoothly rounded longitudinally inwardly directed flange formed about its upper periphery and closes tlie right end of the unit, by joining walls 26 and 32 with support base 12.

A lucking lever 4° is journal!'(1. at an cd 4? for pivotal rotation about a pin 44 pr .trading laterally inw; -dly from upright, wall <() of compartment. 18. The ether end 48 of levei 40 carriM· a downwardly and longitudinally extending, gc,i rally flat plate ‘·Π. - 5 42702 A 1 ticking tang 58 protrudes laterally below the bottom edge of plate; 5θ for cooperative engagement with an aperture 60 (Fig 5) defined in support base 12. Lever 4θ also carries a generally triangular, curved outer wall 62 that acts as a handle and is shaped such that lever 40, when in a closed or locked position, is contiguous at its outer surface boundaries with the outer surfaces of ι·οιιιρ.ιι·Ι.ιω;ηΙ IH. ifcTrrrhig to Figure 4, floor ?4 of compartment 20 carries a plurality oi' protrusions Dial, cooperate with the components of the flow control system shown in Figure 3· Leading to the flow control system is a generally tf-shaped flow passage defined by element 70 that terminates at one end in a needle-like protrusion 7? having a hole 74 that communicates with a small, generally cylindrical interior chamber 76- Spaced from the longitudinally inner face of chamber 76 by an 0-ring 7θ is a filter assembly 80 consisting of one or more filters designed to retain small particles or sediment and bacteria and preclude the passage of the same through the downstream portions of the flow control assembly.

Downstream of filter assembly 80 is a flow pnss.-jge fi? defined by ii groove iri -the longitudinally outer face of elcmf;nt 70 and a flat plate 84 attached thereover. Passage 82 extends through an elbow 66 in clement 70 and diverges to provide chamber 88, it is noted that demerit 70 is constructed so as to join with base 12, the edge of end piece )6, and upstanding walls 22 and 30 at the right-hand ends of compartments 18 and 20 as shown in Figures 1 and 2. Element 70 thus functions as an end wall of a recess 90 of generally rectangular •cross-section on top of base 12 between chambers 18 and 20 and closes off the compartment joining compartments 18 and 20. - 6 10 ('li.ui,hi-r 88 nm: a fj ret outlet 9?’ and a second, smaller 43703 uatJel 94 disposed side-by-fide in a wall %- Ouilets 92 and 94 pro!nidi- sliglitly from the surface of wall 96 and .ire attached iri sealed relationship, to flexible, fluid carry 1:1:- c udiiiI.r ft' and 100, respectively. Ac chowii in Figure 4, a generally ups landing block 102 ic fonried on floor 24 of compartment 20 and includes a pair of longitudinally aligned upstanding dividing walls 104 and 106, Walls 104 and 106 are spaced from each other such that the space between them 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 rads in a connecting block 108 bavin;: inlets 110 and 112 similar to inlets and 94, respectively, and accommodating the ends of flexible conduits 98 and 100 in a fluid-tight manner. Block 108 has a groove running completely around it for fiwn engagement with a generally U-shaped, upstanding protrusion 114 on floor 24 of compartment 20. Λ chamber 116 inside of block 1.08 provides communication between inlets 11.0 and 112 and an outlet 118 for- connection through the floor of compartment 20 with a flexible surgical tube 120. The end of tube 120 is connected with a catheter or needle for infusion of fluids to a patient. Disposed inside of conduit 98 are a plurality of fibers 12? that are nested coextensively in a close relationship and substantially fill the cross-sectional area of conduit 98.

A spring 124 adjacent to elbow 86 other end an offset, Spring 124, exerts a biaein, (Fig 2) is held at one end in a recess 126 in floor ?4 of compartment 2C and has at .its curved portion that engages flexible conduit force If :. itinst the flexible conduit 100 - 7 43702 so as to pinch the same between its curved offset portion and the side of wall 106. Thus, spring 124 normally precludes the passage of fluid through conduit 100 and enables fluid flow therethrough only when it is lifted away from wall 106. Λ generally triangular wedge 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 150 and 152 in the floor of compartment 20. A control wedge 154 is disposed adjacent wedge 128 such that longitudinal movement of the control wedge 1>4 urges wedge 128 into engagement with flexible conduit 98 and compresses th'· conduit between wedge 128, upstanding wall 106, the floor of block 102 and outer wall 26. Such compression distorts conduit 98 such that tlie area therein decreaces resulting in fibers 122 taking up more of the available space within the conduit for fluid flow. At the left end of control wedge 134, as seen in Figure 2, a rack gear 136 is provided having a guide prong 133 protruding from its left end so as to slide against the opposed comer of compartment 20. A pointing arm 140 extends from the left end of rack gear 136 in a direction opposite to projection ?0 150 and has a scribed line 14? for cooperation with a flow rate scale 144 on the outside of wall 26 (Fig l). 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 setting of fluid being dispensed through >5 the infusion unit.

An aperture 148 is defined by the wall 26 for admitting oneend of a tool 15>C' having a pinion gear 152 fonned thereon for int'-iengagement with the gear teeth of rack I36. As indicated in Figure 1, - 8 42708 tool I5O in intended to he inserted through aperture 148 arid rotated so as to longitudinally move control wedge 134 for regulating the force applied through wedge 128 to conduit 98. Tlie flow rate thus established is accurately maintained and is precisely indicated hy the position of pointer 140 on scale 144Chamber 116 in connector block 108 defines a hole 158 opposite inlets 110 and 112, that is closed hy a flexible diaphragm 160 sealed hy an annular clamp 162. Diaphragm 160 thus moves ir; response to the pressure within the system between inlets 110 and 112 and outlet, conduit 120. An L-shaped indicator arm 16/J is pivotally mounted to the floor 24 of compartment 20 and has a first leg 166 that engages and responds to movement of diaphragm 160. The other leg 168 of lever I64 carries a flag or signal 170. Signal 170 may be painted with a bright color or provided with any other suitahle indicia and has an arcuate path of travel that bisects an aperture 172 in wall .’6. fn addition, biasing spring 174 ir- torsionally wound about the pivot axis of arm 164 between leg 168 and a stop 176 on the floor of compartment 20.

In this manner, ana 16/J is biased such that leg 166 ( ngages the diaphragm 160, with leg 168 carrying signal 170 to a nested position hidden behind wall 26 away from aperture I72. Should the catheter or needle become blocked, the pressure of th,.· fluid supply causes diaphragm 160 to bulge outwardly from ?5 connector block 108 thereby rotating arm 164 and transposing signal 170 to a position behind aperture 172. The visual perception of signal 170 through aperture 172 notifies the patient or his - 9 42703 attending physician or nurse that infusion has ceased. The above described flow indicator is entirely optimal. Λ plurality of grooves such as orthogonal grooves 180, . ? and 184 arc formed in the undersurface of support base 12 in order to allow 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 conduit in the most convenient manner. Any number of such grooves may he provided in the undersurface of support base 12. Λ cartridge assembly 200 formed of left and right cartridge halves 202 and 204, respectively, as shown in Figure 6 has a generally rectangular cross section and conforms to recess 90 between compartments 18 and 20, The upper surfaces of halves 202 and 204 are slightly curved such that when the cartridge is slid into recess 90 and arm 40 is pivoted to its locked position, the overall unit has a smooth outer surface as shown in Figure 1.

Half 204 has an end wall 206 defining an aperture 208. Aligned with aperture 208, inside cartridge assembly 200, is a valve assembly 210 of a distensible fluid-container bladder 212.

Valve assembly 210 is attached to wall 206 in any suitable manner such as by means of clamps, bolts, or inter-locking grooves.

Tlie basic element of valve assembly 210 is a flat, . resilient member 214, having a pair of frustoconical apertures 215, that, as shown in Figure 7 in solid lines, is urged by ?5 the internal pressure within the bladder into a cloned position in sealed engagement with wall 206. Alternatives to valve 210 are a simple flap valve or a flexible seal puncturable by a needle for admitting or dispensing fluid. Such alternatives would require modification of projection 7? or substitution of a sharp !0 needle therefor.

The opposite end of bladder 212 defines an opening 216 having an annular flange 218. Aligned over opening 216 against the surface of flange 218 is a microfilter 220 which allows the passage of air but not fluid.

Microfilter 220 is firmly clamped between flange 218 and the longitudinally inner flat surface of a sliding spider 222 having a plurality of arms 224 extending radially from a central hub. Arms 224 are preferably engaged with the four inner· corners of the rectangular shell provided by halves 202 and 204 of cartridge 200 such that the spider is freely elidable longitudinally within the shell. An aperture 226 extends completely through the central hub of spider 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 spider 222 and lias a first leg that extends over a recessed path 230 longitudinally disposed along a central portion of half 204. Λ volume scale 232 is imprinted upon the upper surface of half 204 and cooperates with indicator arm 228 to indicate the volume of fluid in the bladder 212.

Bladder 212 may be distended by tlie admission of fluid under pressure through valve 210 such that the bladder is axially and radially enlarged, as shown in Figure 2, for sto’ ing the fluid und-r pressure. As the fluid is forced into bladder 2 ·!, tlie bladder becomes axially elongated such that spider 222 j. .ides toward the end away from the valve 210, with pointer 828 indica ing the volume of fluid admitted on scale 232. in addition, since bladder 212 is supported between valve assembly 210 attached to wall 206 of cartridge 200 and the central hub of spider 222, the same is at all times spaced - 11 42702 from tho inner walls of halves 202, 204 to allow precise delivery of the entire contents of the bladder with minimal frictional interference.

Furthermore, the distensible elastic wall of bladder 212 is constructed so that it distends radially only to approximately the inner dimensions of the cartridge 200. Λ pair of pins 240 and 241 protrude laterally from the ends of a side wall of half 202 of cartridge 200 for cooperative engagement with the inner edge of plate 50 and flange 46, respectively. Thus, as cartridge 200 is slid into position along support base 12 (Fig 4), pin 241 engages flange 45 and as arm 40 is rotated downwardly, pin 240 slides along said inner edge to firmly urge the cartridge into a nested position with pin 72 inserted through aperture 208 and into engagement with member 214 of valve assembly 210.

In operation, a particular liquid drug intended to be administered by infusion to a patient is first forced under pressure into bladder 212 through valve assembly 210. An appropriate interface may be formed on the valve end of cartridge 200 for cooperation with a supply capsule such that the liquid drug supply may be affixed to the carl ridge 200 with a noedle-like member engaging member 214 of the valve assembly to open tho same for the admission of drug. The incoming drug causes bladder 212 to radially and axially expand to a capacity of from 20 to 100 co. While the drug is being forced into bladder 212, spider 222 moves axially toward the end opposite valve assembly 21.0, indicating the volume of drug in the bladder by the position of pointer arm 228 on scale 232. 49ros After Wackier 212 ha;: been completely filb'4, I hi? liquid drug supply is removed from the cartridge allowing member 214 to become firmly seated against wall 206. The cartridge? is then ready for u: ·.and may he stored under appropriate condi tions or immcdiul cly inns·» t»d into the unit for use. During the filling operation, mi crofiitor 220 allows any air initially contained within the deflated bladder 217 to pass through aperture 226 in spider 27.2 for assuring complete filling of the bladder with tin· liquid drug, hy t.iJIiinj Un? ca»1 ridge r.uoh ι that the end opposite valve assembly 210 is in an elevated position, Ιθ the air trapped within bladder 212 will rise to the top and will bo slowly released through filter 220 to the atmosphere. As noted above, microfilter 220 may be of any suitable type, such as that sold und r the designation Celgard, and enables the passage of air but ye preclude.'-, the flow of the liquid drug out of the bladder under bla ider pres,·.ure, thereby enublji.q rapid bleeding (if the bladder so that, i will be filled only with Ihe liquid drug.

Onco the cartridg ? assembly has been completely filled wit > liquid drug, and it in de sired to administer tlie drug to a patient the cartridge may be properly positioned in recta 90 between comp irt20 ments 18 and 20. Preferably, cartridge 200 is positioned nt the left end of recess 90, with locking arm 40 in approximately the position illustrated in Figure 4. The cartridge is then gently slid to the right between walls 22 and 30. As shown in Figures 2 and 7, as the cartridge moves toward the right end of tho unit, projecting pin 72 of end member 70 first passes through aperture 208 in the wall of the cartridge and, as the cartridge is further advar cd, pushes member 214 into i.ts open position (illustrated in phantom i i Figure 7), thereby - 13 43702 pcnni Lting Iiquid drug to flow through apertures 215 and slots or openings (not shown) in the leading end of pin 72 and into hole 74.

At this same time, lever 40 must be moved downwardly toward its looking position. This causes pin 240 to slide along tlie inner edge of plate 50 and urge the cartridge into its properly nested position alop supjiort base 12. After the cartridge is fully seated to tlie right as shown in Figure 2, lever 40 may be further moved such that the locking tang 58 engages the shoulder of rectangular opening 60· in base 12 and firmly locks the cartridge in place. As indicated in Figure 1, when the cartridge is positioned atop support base 12, and lever 40 is rotated down into its locked position, the unit has a smooth, continuous exterior surface.

With the cartridge in position atop base 12, the interaction of pin 72 and member 214 allows the liquid drug to flow from bladder 212 into fluid passageway 82 formed in the Tight end of the unit. The drug flows through aperture 74 and into chamber 76 where it must pass through filter 80 thereby assuring tlie removal of any bacteria, sediment or other small particles which may have inadvertently entered the system. While the liquid drugs that must be expected to be administered with the unit will hot normally contain any large particles the filter 80 assures the complete removal of such particles, thereby guarantoring positive metering of drug through the fluid flow control described below.

The fluid passage 82 opens into chamber 88 that 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 conduit providing precise and accurate metering 43708 of drug 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 and through conduit 120 '< for infusion. While th · particular details of conduit 120 have not been shorn, it should be understood that any well-known surgically approved technique may be utilized whereby the conduit 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, the spring 124 (Fig 2) has an offset, curved end which is normally biased into engagement with conduit 100 so as to pinch it against wall 106 and close it to the passage of fluid frora cartridge 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 unit for use. Thus, spring 1?4 is provided for cooperation with 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 conduit 100 is again dosed. As shown in Figure 1., opening 148 may be provided in the wall 26 of compartment 20 to enable a flat blade of tool ISO to be inserted into compartment 20 for moving spring 124 away from 2‘) conduit 100.

The fibers 122 in conduit 98 are essentially linear and are made of a resilient elastomeric material, such as poly(urethane) - 15 43702 silicone rubber, polyisoprene and butyl rubber. Since conduit 98 rests iri position atop block 102 between wall 106 and a flat side: of wedge member 176, a compressive force is applied to the conduit by wedge 128 in a direction which is perpendicular to the flow of fluid therethrough. This compressive force is applied to the conduit along a face where the fibers 122 are disposed, and may be applied over all or part of the length of the fibers.

As a compressive force is applied agairisl. conduit 9(1 hy the wedge 178, the conduit is deformed. Since the crosssectional peripheral length of conduit 98 does not change appreciably, hill:: deformation bi-ings about a decrease in tiie conduit's cross-sectional area. The cross-sectional area of the fibers 172, however, does not change appreciably oo that as conduit 9θ is compressed, the proportion of the space within the conduit taken up by the fibers increases to enable precise metering of fluid flow. Fibers 172 are closely packed within the conduit and generally should take up at least 50 precent of the internal cross-sectional area of the conduit prior to compression.

Preferably, the fibers have circular cross-sections so that they align in a close—packed, nested configuration. The number of fibers may vary. As a general rule, there must be at least six fibers and the upper limit, which is not critical, may be as much as several hundred fibers.

In ordci to precisely control tin flow iate ihrough conduit ‘Hi, control wedge lid is disposed in co’iip.ii tmenl 7(1 and enacts wi lh wedge .128 such that changing the longitudinal position of control wedge lji causes very slight movements of wedge 128 perpendicular to the conduit. In this manner, compressive forces of greater and lesser magnitude are - 16 4270S simply, effectively, and reproducibly generated and applied by wedge 28 to conduit 98. The control wedge 134 eaiJ-ie: a rack gear 220 which, as noted above, iii acccnsible through aperture 148 in wall 2b of compartment 20. Pinion gear 152 of tool 150 may be easily inst-rlcd throw;!* aperture 148 ao a: to engage rack gear 136. Rotation of the tool chnngea the longituii.nal position of control wedge 134.

Since the position of control wedge 134 determineK the compreaoive force applied to conduit: 98, and thus, tho flow rate of liquid from the unit, the position of pointer arm 140 on scale 144 enables the simi le and precise visual pereep ion of the preselected flow rate. Once the desired flow rate has been established, tool 150 may be removed so as to preclude inadvertent adjustment or regulation of tlie flow rate. Of course, by subsequent, rei isertion of the pinion gear 152 of tool 110, tlie flow rate may lit rese:.

Conduits 58 and 180, fibers 122, and bladder 212 may lie fo: ned of the same material or oi different materials. While any number Referring to Figure 1., the infusion unit ie preferably di.sign.-d to be worn or all ached to a portion of the torso or an extra Ely .,1 a pal 11-1,1- and is particular'/ *.-· II .aided tor admi a i..t el i i g loniid drug*.

- If 42702 at very slow rates over an extended period of time to a particular site of disease or infection. 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, Lhe infusion unit is attached to tlie patient's upper arm or forearm with the slight curvature of the lovrer surface of the support base 12 generally conforming to the curvature of the arm. Straps 14 and 16 may be adjusted so that the infusion unit is comfortably held in position about the arm of the patient.

Tho conduit 120 may then be positioned within one of the orLliogonal 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 catheter. Desirably conduit 120 is of the nonclosure type, that is, its passageway in of a generally triangular crosi; section which prrevents .it from being easily pinched off.

Preferably, before the infusion unit is attached to the patient, a cartridge 200 whi ch has been previously filled wit h tlie desired d t ug to be administered is slid onto the support base 12 in the I'lariner described above. Thereafter, the blade end of tool 150 may be inserted through thi? opening in the unit's wall to lift spring 124 away from conduit 100 causing the relatively rapid emission of drug from cartridge 212 through the passage.ways inside the infusion unit and thence through conduit 120 and the catheter so as to discharge al.1 of the air present within the flow passageway of the unit. Spring 124 is thereafter released closing conduit 100 and allowing the desired, precisely metered flow rate to be est ubli.eb.-d t lirougji conduit 91:, - 18 48703 Tin· cut holer it: then insrxlod into the selected tiusn·· or vascular pannage annociated with tlie disease site to be treated, arid the precise, desired flow rate is preset by insertion and rotation of tool 150 tbro’ijli opening 148. The unit will thon continuously administer ’’ liquid drug to the patient at the selected flow rate.

The infusion unit: it; preferably constructed of molded plastics so as to be extremely lightweight and economical to fabricate, finch molding may be accomplished by well-known techniques and, as such, may be fabricated from a number of individually molded pieces that- are i° assembled to form the unit.

It can therefore be appreciated that the unit jwvides a number of material advantages over prior devices and allows precisely re).reducible,metered flow rati o of liquid dings to be administert d to a pal rent by infusion by apparatus which is economical, simple, aesthetically pleasing, and allows tho patient Lo be at all times ambulatory while undergoing treatment. Further, the .infusion unit may easily accommodate any number of replaceable cartridges containing the same or different liquid drugs for administration to a patient at v.n icus limes, (..ach cartridge being rof.illablc ox disposable inter Ί> such patient has completed the intended treatment.

Claims (9)

1. A liquid infusion unit for infusing liquid drug continuously into a patient at a controlled rate characterised by: (a) an elongate housing having means for attachment to the 5 patient and having a recess in its exterior surface; (b) a liquid drug flow passageway enclosed within the housing and having an inlet and an outlet; (c) a cartridge for containing the liquid drug under pressure that removably fits in the recess on the exterior surface of the 10 housing such that the unit has a smooth, contiguous exterior surface, the cartridge having an outlet for the liquid drug that connects with the inlet of (b) when the cartridge is fitted in the recess; (d) a flow controller in (b) between the inlet and outlet 15 of (b) that regulates precisely the flow rate of liquid drug through (b); and (e) a conduit connected to the outlet of (b) that extends to the infusion site.

2. A unit as claimed in claim 1 characterized by the unit 20 having a generally crescent-shaped transverse cross section and being comprised of a concave bottom wall, a convex top wall and two opposed end walls. J. A unit as claimed in claim 2 characterized by the recess having a IT-shaped transverse cross section and being located 25 axially in the housing with one end opening through an end wall of the housing and the opposite end being closed by the opposite end wall of the housing, such that, with the cartridge correctly positioned therein the convex top wall of the unit is formed. - 20 43702 1. A unit as claimed in either oi* claims 2 or < characterized hy the cartridge having a crocs section that eon)'· tine to thi· recess 'iocs aeotion and a top wall portion of a c.onvr' pi.'fil* co . with the top wall portion of the housing it forms the convex top wall of the unit.

3. 5. A unit as claim'd in claim 3 or claim 4 characterized hy the inlet of (li) bei ig in the surface of the opposite end wall of the housing that defines the closed end of the recess.

4. 6. A unit as claimed in any one of claims 1-5 characterized by (b) having a filter in it between its inlet and (d).

5. 7. A unit as claimed in any preceding claim characterized by (b) being connected to a flow indicator means that is respons vp to the hydraulic pressure within (b). B. A unit as claimed in claim 1 characterized by (b) including a bypass, of (d). A unit as claim‘d in any one of claims 2 to

6. 8 charm tericed by tiie cartridge comprising a hollow shell having a crocs aeolian that conforms to the recess cross section and a top wall of the same convexity as the top wall portion of a convex profile so as with the top wall portion of the housing it forms the convex top wall of tlie unit, and a generally cylindrical elastomeric bladder contained within the shell and adapted to contain the liquid drug under a pressure generated by the resilience cf the bladder. 10. A unit as claimed in claim 9 characterised by the i-arlrid.'C' including a valve assembly connected to one on'! of the bl.-nid· r, tee valve assembly defining tlie cartridge outlf I and bring atlacimi t. tin- inside of an end wall of the shell. 21 42702 11. A unit as claimed, in claim 10 characterized hy the cartridge including a spider attached to the other end of the bladder whose arms slidably engage the inside of the shell, the valve assembly and spider supporting the bladder within the shell such that the 5 bladder wall is at all times spaced from the longitudinal walls of the shell. 12. A unit as claimed in claim 10 or claim 11 characterized hy the other end of the bladder being closed by a microfilter that permits air but not liquid to pass. 10 13- A unit as claimed in claim 11 or claim 12 characterized hy the top wall of the shell having an aperture parallel to the long axis of the unit, whose axial edge carries a bladder volume scale and one arm of the spider acts as a bladder volume indicator in cooperation with the bladder volume scale. 15 14- A unit as claimed in claim 5 characterized by the cartridge comprising a hollow shell having a cross section that conforms to the recess cross-section and a convex top wall, and a generally cylindrical elastomeric bladder contained within the shell and adapted to contain the liquid drug under a pressure 20 generated by the resilience of the bladder and a valve assembly connected to one end of the bladder, the valve assembly defining the cartridge outlet and heing attached to the inside of an end wall of the shell, the inlet of (b) being defined by a needlelike protrusion that extends ;aially from said surface arid penetrates 25 the valve assembly when the cartridge is seated in the rccecc, thereby opening the valve and permitting the liquid drug to flow from the bladder into (b). - 22 42703 13. A unit ar cl..ir d in an,, preceding claim characferizcd ly the unit including a locking lever pivotally attached to the housing Hint, engages the* cartridge and locks it in place within tne rc-cess. 16. A unit as claimed in any preceding claim characterized by

7. 9 the flow controller comprising a deformable conduit through which the liquid drug flows, a plurality of parallel, linear elongate fibers disposed cocxterisively in the conduit and an adjustable means disposed about- the conduit for pinching the conduit to varying degrees whereby the flow rale of liquid drug may h vjii-d.

8. 10 17. Λ unit ns claimed 'Π claim lo chaiac t>·ri.>·() bj ii,adjusl.ablc mc.iri:: being u piti ι of vug··:: <1ϊ:ψο··ι| ad,pa· ι n 1. I.lr conduit facing each othj, Uf of the wedge·:, bring tiansv' rc J;, movable and the other w-dgi.· being longitudinal iy movable and the housing having an nperi ire therein i-o provide ..'ciri: te t-l.rJh longitudinally mov.iidc wedge for ad jusi-mt n! of tir· ra’iie. lfi. A unit, as claimed in claim 17 characterized by the housing; top wall portion having an aperture with a flow rate scale oi cm of its edges and the axially movable wedge carrying a pongee th: t cooperates with the flow rate scale to indicate the flow rate. 20 1

9. A liquid infusion unit substantially ac herein desuribod witii reference to and as illustrated in the aucompanying browing:·.