IL46521A - Unit for infusing a liquid drug continuously into a patient at a controlled rate - Google Patents

Abstract

An improved infusion unit for intramuscular, subcutaneous intravascular delivery of liquid drug to a patient is disclosed and includes (a) a compartmented housing carrying a (b) removable, refillable liquid drug cartridge selectively communicating with a (c) fluid passageway in the housing and suitably connected with a (d) catheter. The cartridge contains a distensible bladder or liquid repository leading to an adjustable fluid flow controller disposed in the passageway and which accurately meters the amount of liquid drug dispensed from the bladder to the patient. The unit is completely self-contained and can be conveniently attached to the patient near the point of infusion for ambulatory use. [US3895631A]

Description

UNIT FOR IKFUSING A LIQUID DRUG CONTIGUOUSLY INTO A PATIEMT AT A CONTROLLED RATE ABSTRACT OF THE DISCLOSURE A liquid infusion unit for infusing liquid drug continuously into a patient at a controlled rate is disclosed. The unit comprises: a housing that is adapted to be attached to the patient; a removable, refillable liquid drug cartridge that fits into a recess in the housing exterior; a liquid drug flow passageway enclosed within the housing whose inlet connects with the cartridge outlet; an adjustable flow controller in the passageway that regulates precisely the flow rate of liquid drug; a conduit connected to the outlet of the passageway that extends to the infusion site; and a catheter or needle connected to the end of the conduit that is inserted into the patient at the infusion site.

BACKGROUND OF THE INVENTION 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 various liquids, including liquid drugs, at accurate, reproducible flow rates to a patient. The prior art is generally cognizant of such devices, as exemplified by U.S. Patent No. 2,842,123 to Rundhaug that shows a transfusion apparatus having a collapsible bag for the fluid and a pressure container in sealed relationship about the outside of the bag; U.S. Patent No. 2,847,007 to Fox that discloses a flexible fluid pouch within a resilient container for storing whole blood or plasma; U.S. Patent No. 3,469,578 to Bierman that illustrates an infusion device having a spigot valve for ambulatory use; and U.S. Patent No. 3,486,539 to Jacuzzi, that shows a liquid dispensing device having a restricted outlet passage.

Such devices, while generally satisfactory, have 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 the aesthetically displeasing mechanical appearance of such devices have 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 are dispensed; and at very low flow rates in the range of 0.1 to 10 cc per hour varying 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 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 wij^ 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 .

STATEMENT OF THE INVENTION The invention is a unit for infusing a liquid drug continuously into a patient at a controlled rate characterized by: (a) a housing adapted to be attached to the 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 adapted to contain the liquid drug under pressure that removably fits within the recess in the 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 said passageway when the cartridge is fitted in the recess; (d) a flow controller in said passageway between the inlet and outlet of said passageway that regulates precisely the flow rate of liquid drug through said passageway; and (e) a conduit connected to the outlet of said passageway that extends to the infusion site.

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

U.S. Patent 3 468 308 to Bierman discloses a device for receiving and expelling a small volume of liquid at a controlled rate however in contradistinction to the present invention the device does not have a housing having an exterior recess that receives a cartridge as hereinbefore described. Also the flow control element of the disclosed device is exposed to the patient rather than being confined within the housing.

U.S. Patent 3 543 753 to einstein discloses an intervenous infusor comprising a chambered container, an opening for the selective introduction of compressed gas for forcing out fluid contained in the container, in combination with a flow tube and a hypodermic needle assembly having a valve to regulate flow. This infusor however, does not involve a removable cartridge that fits into a recess in the exterior of a housing as in the present invention and also, the flow regulator of this US Patent is not confined within a housing but instead is exposed to the patient. - 3 a - BRIEF DESCRIPTION OF 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 the 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 the fluid repository cartridge of the infusion unit of Figure 1; and Figure 7 is a sectional view of a detail of the valve assembly of the cartridge of Figure 6.

DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, the preferred embodiment of the infusion unit of the invention includes a main housing 10 having 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 the 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 bands 14 and 16 affixed to the underside of the base 12.

Alternative devices to 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 cross section as shown in Figures 1 and 4. Compartment 20 is defined by a generally flat, upright interior wall 22, an outwardly and downwardly inclined floor 24, and a generally flat inclined outer wall 26. The end of compartment 20, to the left as seen in Figure 1, is closed by a triangularly-shaped wall 28 that is contiguous at its periphery with walls 22, 26 and the support base 12.

Compartment 18 has along its inner side a generally upright wall 30 that extends from support base 12 to the upper edge of a flat, inclined outer wall 32 that joins base 12 along its longitudinal edge. The left end of compartment 18, 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 base 12 in a manner similar to that of compartment 20. A convex wall 36 of generally triangular configuration has a smoothly rounded inwardly directed flange formed about its upper periphery and closes the right end of the unit by joining walls 26 and 32 with 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 limit the degree of upward swing of lever 40 away from 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 support base 12. Lever 40 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 compartment 18.

Referring to Figure 4, floor 24 of compartment 20 carries a plurality of protrusions that cooperate with the components of the flow control system shown in Figure 3. Leading to the flow control system is a generally U-shaped flow passage defined by element 70 that terminates at one end in a needle-like protrusion 72 having a hole 74 that communicates with a small, generally cylindrical interior chamber 76. Spaced from the front wall of chamber 76 by an 0-ring 78 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 passage 82 defined by a groove in the outer wall of element 70 and a flat plate 84 attached thereover. Passage 82 extends through an elbow 86 in element 70 and diverges outwardly to provide an interior chamber 88. 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. Element 70 thus functions as an end wall of the generally rectangular recess 90 on top of base 12 between chambers 18 and 20 and closes off the compartment joining compartments 18 and 20.

Chamber 88 has a first outlet 92 and a second, smaller outlet 94 disposed side-by-side in a wall 96. Outlets 92 and 94 protrude slightly from the outer surface of wall 96 and are attached in sealed relationship, to flexible, fluid carrying conduits 98 and 100, respectively. As shown in Figure 4, a generally rectangular upstanding block 102 is formed in 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 ends in a connecting block 108 having inlets 110 and 112 similar to inlets 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, but may be shaped otherwise. Block 108 has a groove running completely around it for firm engagement with a generally U-shaped, upstanding protrusion 114 in floor 24 of compartment 20.

A chamber 116 inside of block 108 provides communication between inlets 110 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 122 that are nested coextensively in a close relationship and fill a A spring 124 (Fig 2) is held at its proximal end in a recess 126 adjacent to elbow 86 in floor 24 of compartment 20 and has at its distal end an offset, curved portion that engages flexible conduit 100. Spring 124, when disposed in recess 126, exerts a biasing force against the flexible conduit 100 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.

A 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 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 and compresses the conduit between wedge 128, upstanding wall 106, the floor of block 102 and wall 26. Such compression distorts conduit 98 such that the area therein decreases 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 138 protruding from its left end so as to slide against the front corner of compartment 20. A pointing arm 140 extends from the left end of rack gear 136 in a direction opposite to projection 138 and has a scribed line for cooperation with a flow rate scale 144 on 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 setting of fluid being dispensed through the infusion unit.

An aperture 148 is defined by the wall 26 for admitting one end of a tool 150 having a pinion gear 152 formed thereon for inter-engagement with the gear teeth of rack 136. As indicated in Figure 1, tool 150 may be inserted through aperture 148 and rotated so as to longitudinally move control wedge 134 for regulating the force applied through wedge 128 to conduit 98. The flow rate thus established is accurately maintained and is precisely indicated by the position of pointer 140 on scale 144.

Chamber 116 in connector block 108 defines a hole 158 opposite inlets 110 and 112, that is closed by a flexible diaphragm 160 sealed by an annular clamp 162. Diaphragm 160 thus moves in response to the pressure within the system between inlet 110 and outlet conduit 120. An L-shaped indicator arm 164 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 164 carries a flag or signal 170. Signal 170 may be painted with a bright color or provided with any other suitable indicia and has an arcuate path of travel that bisects an aperture 172 in wall 26. 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, 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 behind aperture 172. The visual 4 perception of signal 170 through aperture 172 notifies the patient or his attending physician or nurse that infusion has ceased. The above described flow indicator is entirely optimal.

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 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 be provided in the undersurface of support base 12.

A cartridge assembly 200 formed of left and right cartridge halves 202 and 204, respectively, 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, contiguous outer surface as shown in Figure 1. Halve 204 has an end wall 206 defining an aperture 208. Aligned over aperture 208 is a valve assembly 210 of a distensible fluid-containing bladder 212. Valve assembly 210 is attached to wall 206 in any suitable manner such as by means of clamps, bolts, or interlocking grooves.

The 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 the internal pressure within the bladder into a closed position in sealed engagement with wall 206. Alternatives to valve 210 are a simple flap valve or a flexible seal adapted to be punctured by a needle for admitting or dispensing fluid. Such alternatives would require 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. 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 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 slidable 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 has a first leg that extends over a recessed path 230 longitudinally disposed along a central portion of halve 204. A volume scale 232 is imprinted upon the upper surface of halve 204 and cooperates with indicator arm 228 to indicate the volume of fluid in the bladder 212.

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 Figure 2, for storing the fluid under pressure. As the fluid is forced into bladder 212, the bladder becomes axially elongated such that spider 222 slides toward the end away from the valve 210, with pointer 228 indicating 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 from the 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. Therefore, even when fully distended, it does not engage the inner walls of halves 202, 204.

A pair of pins 240 and 241 protrude laterally from the ends of a side wall of halve 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 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 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 cartridge 200 with a needle-like member engaging member 214 of the valve assembly to open the same for the admission of drug. The incoming drug causes bladder 212 to radially and axially expand to a capacity of from about 20 to 100 cc. While the drug is being forced into bladder 212, spider 222 moves axially toward the end opposite valve assembly 210, indicating the volume of drug in the bladder by the position of pointer arm 228 on scale 232.

After bladder 212 has been completely filled, the liquid drug supply is removed from the cartridge allowing member 214 to become firmly seated against wall 206. The cartridge is then ready for use and may be stored under appropriate conditions or immediately inserted into the unit for use. During the filling operation, microfilter 220 allows any air initially contained within the deflated bladder 212 to pass through aperture 226 in spider 222 for assuring complete filling of the bladder with the liquid drug. By tilting the cartridge such that the end opposite valve assembly 210 is in an elevated position, the air trapped within bladder 212 will rise to the top and will be slowly released through filter 220 to the atmosphere. As noted above, microfilter 220 may be of any suitable type, such as that sold under the designation "Celgard," and enables the passage of air but yet precludes the flow of the liquid drug out of the bladder under bladder pressure, thereby enabling rapid bleeding of the bladder 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 drug to a patient, the cartridge may be properly positioned in recess 90 between compartments 18 and 20. Preferably, cartridge 200 is positioned at 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 the unit, projecting pin 72 of end member 70 first passes through aperture 208 in wall 206 of the cartridge and, as the cartridge is further advanced, pushes member 214 into its open position (illustrated in phantom in Figure 7) , thereby Τ permitting liquid 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 locking position. This causes pin 240 to slide along the inner edge of plate 50 and urge the cartridge into its properly nested position atop support base 12. After the cartridge is fully seated to the 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 right end of the unit. The drug flows through aperture 74 and into chamber 76 where it must pass through filter 80 thereby assuring the removal of any bacteria, sediment or other small particles which may have inadvertently entered the system. While the liquid drugs that might be expected to be administered with the unit will not normally contain any large particles the filter 80 assures the complete removal of such particles, thereby guaranteeing 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 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 the particular details of conduit 120 have not been shown, 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, a spring 124 (Fig 2) has an offset, curved distal 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 from 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 124 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 closed. As shown in Figure 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 compartment 20 for moving spring 124 away from conduit 100.

Conduit 98 contains a plurality of coextensively disposed, parallel, elongated fibers 122 that substantially fill the conduit.

Fibers 122 are essentially linear and are made of a resilient elastomeric material, such as the poly (urethane) sold under the designation "Lycra Spandex," silicone rubber, polyisoprene and butyl rubber. Since conduit 98 rests in position atop block 102 between wall 106 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 fibers 122 are disposed, and may be applied over all or part of the length of the fibers.

As a compressive force is applied against conduit 98 by the wedge 128, the conduit is 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 fibers 122, however, does not change appreciably so that as conduit 98 is compressed, the proportion of the space within the conduit taken up by the fibers increases to enable precise metering of fluid flow. Fibers 122 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 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 order to precisely control the flow rate through conduit 98, control wedge 134 is disposed in compartment 20 and coacts with wedge 128 such that changing 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 conduit 98. The control wedge 134 carries a rack gear 136 which, as noted above, is accessible through aperture 148 in wall 26 of compartment 20. Pinion gear 152 of tool 150 may be easily inserted through aperture 148 so as to engage rack gear 136. Rotation of the tool changes the longitudinal position of control wedge 134.

Since the position of control wedge 134 determines the compressive force applied to conduit 98, and thus, the flow rate of liquid from the unit, the position of pointer arm 140 on scale 144 enables the simple and precise visual perception 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 the flow rate. Of course, by subsequent reinsertion of the pinion gear 152 of tool 150, the flow rate may be reset.

Conduits 98 and 100, fibers 122, and 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 unit. Exemplary materials include natural rubber (preferably treated to remove impurities which potentially would contaminate the fluid) , as well as synthetic elastomers, for example, poly (isoprene) , pol (1 ,4-butadiene) , segmented polyurethane of the poly-ether variety, block co- or ter-polymers containing butadiene and styrene, silicone rubbers, butyl rubber, nitrile/butadiene rubber and neoprene.

Referring to Figure 1, the infusion unit 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 for administering liquid drugs 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, the infusion unit is attached to the patient's upper arm or forearm with the slight curvature of the lower 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.

The conduit 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 catheter. Desirably conduit 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 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 unit's wall to lift spring 124 away from conduit 100 causing the relatively rapid emission of drug from cartridge 212 through the passageways inside the infusion unit and thence through conduit 120 and the catheter so as to discharge all 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 established through conduit 98.

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 unit will then continuously administer liquid drug to the patient at the selected flow rate.

The infusion unit is preferably constructed of molded plastic so as to be extremely lightweight and economical to fabricate. Such molding may be accomplished by well-known techniques and, as such, may be fabricated from a number of individually molded pieces that are assembled to form the unit.

It can therefore be appreciated that the unit provides a number of material advantages over prior devices 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 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, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not limiting.

Claims (18)

WHAT IS CLAIMED IS:

1. A unit for infusing a liquid drug continuously into a patient at a controlled rate characterized by: (a) a housing adapted to be attached to the 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 adapted to contain the liquid drug under pressure that removably fits within the recess in the 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 said passageway when the cartridge is fitted in the recess; (d) a flow controller in said passageway between the inlet and outlet of said passageway that regulates precisely the flow rate of liquid drug through said passageway^ and (e) a conduit connected to the outlet of said passageway that extends to the infusion site.

2. The liquid infusion unit of claim 1 characterized by the housing having a generally crescent-shaped cross section and being comprised of a concave bottom wall, a convex top wall and two opposed end walls.

3. The liquid infusion unit of claim 2 characterized by the recess having a rectangular cross section and being located axially in the top wall with one end opening through one end wall of the housing and the opposite end being closed by the opposite end wall of the housing. - - 46521/2

4. The liquid infusion unit of claim 3 characterized by the cartridge having a cross section that cnnforms to the recess cross section and a top wall of the same convexity as the top wall of the housing.

5. The liquid infusion unit of claims 3 and 4 characterized by the inlet of said passageway being in the surface of the opposite end wall of the housing that defines the closed end of the recess.

6. The liquid infusion unit of any of claims 1-5 characterized by said passageway having a filter in it between its inlet and said flow controller.

7. The liquid infusion unit of any of claims 1-6 characterized by said passageway being connected to a flow indicator that is responsive to the hydraulic pressure within said passageway.

8. The liquid infusion unit of claim 1 characterized by said passageway including a bypass of said flow controller.

9. The liquid infusion unit of any of claims 1-8 characterized by the cartridge comprising a hollow shell having a cross section that conforms to the recess cross section and a top wall of the same convexity as the top wall of the housing, and a generally cylindrical elastomeric bladder that is contained axially within the shell and is adapted to contain the liquid drug under a self-generated pressure.

10. The liquid infusion unit of claim 9 characterized by the cartridge including a valve assembly connected to one end of the bladder, the valve assembly defining the cartridge outlet and being attached to the inside of an end wall of the shell.

11. The liquid infusion unit of claim 10 characterized by 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 bladder wall is at all times spaced from the longitudinal walls of the shell.

12. The liquid infusion unit of claims 10 and 11 characterized by the other end of the bladder being closed by a microfilter that permits air but not liquid to pass.

13. The liquid infusion unit of claims 11 and 12 characterized by the top wall of the shell having an axial aperture 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.

14. The liquid infusion unit of claim 5 characterized by the cartridge comprising a hollow shell having a cross section that conforms to the recess cross section and a top wall of the same convexity as the top wall of the housing, and a generally cylindrical elastomeric bladder that is contained axially within the shell and is adapted to contain the liquid drug under a self-generated pressure and a valve assembly connected to one end of the bladder, the valve assembly defining the cartridge outlet and being attached to the inside of an end wall of the shell, the inlet of (b) being defined by a needle-like protrusion that extends axially from said surface and penetrates the valve assembly when the cartridge is seated in the recess, thereby opening the valve and permitting the liquid drug to flow from the bladder into (b) .

15. The liquid infusion unit of any of claims 1-14 characterized by the unit including a locking lever pivotally attached to the housing that engages the cartridge and locks it in place within the recess.

16. The liquid infusion unit of any of claims 1-15 characterized by the flow controller comprising a deformable conduit through which the liquid drug flows, a plurality of parallel, linear elongate fibers disposed coextensively in the conduit and an adjustable pincher disposed about the conduit for pinching the conduit to varying degrees whereby the flow rate of liquid drug may be varied.

17. The liquid infusion unit of claim 16 characterized by the pincher being a pair of wedges disposed on opposite sides of the conduit facing each other, one of the wedges being fixed and the other wedge being axially movable and the top wall of the housing having a hole in it providing access to the axially movable wedge to move the same.

18. The liquid infusion unit of claim 17 characterized by the top wall having an aperture with a flow rate scale on one of its edges and the axially movable wedge carrying a pointer that cooperates with 19· A liquid infusion unit for Infusing liquid drug continuously into a patient et e controlled rate substantially m hereinbafore described t?ith reference to and as illustrated in the neeonpanying drawings*