USH150H - Accessory module for implantable fluid dispensing device - Google Patents

Abstract

An implantable fluid dispensing device has an accessory housing set into the biocompatible shape of its device canister. A shelf is set into the canister to accept the accessory housing which contains a filter, an externally accessible infusion septum, or other accessory. The function of accessories in the accessory housing is independently tested. After an accessory is selected to match the particular application, the accessory module is mounted on the canister.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to accessory modules designed for mounting on implantable fluid dispensing devices.

2. Background Art

A variety of fluid dispensing devices have attempted to more carefully regulate diseases or pain in patients by delivering drugs to particular sites within the body. For example, it is believed that insulin delivery by an implantable dispenser will regulate diabetes in a manner impossible through traditional injections.

These devices must be sealed to prevent migration of fluids between the patient's body and the interior of the device. The common technique has been to weld shut a metallic container, using technology similar to that in heart pacemakers. This method of sealing a case is effective, but is permanent and expensive to alter. Components within the case must be considered permanently encapsulated.

Particular applications of such fluid dispensing devices could be enhanced by having various accessories in combination with the permanent parts of the device, which reside within the case. For example, some drug therapies are safer if the drug is filtered for either particles or bacteria. Because each drug and therapy has specific characteristics, it is expensive and impractical to design a variety of such filters as part of the permanent apparatus sealed within the case.

Another example of an accessory for the module is a port for infusion of drugs on an acute basis, to supplement the chronic administration provided by the fluid dispensing device. Attempts have been made to add external ports to be used in conjunction with such devices. For example, see the port disclosed in U.S. Pat. No. 4,360,031 to White, issued Nov. 23, 1982. An external port is disclosed in U.S. Pat. No. 3,971,376 to Wichterle issued July 27, 1976.

A means is needed to accommodate such drug-specific and application-specific devices other than permanently mounting them within the sealed case. Great manufacturing expense can be saved if accessory devices can be added after the original manufacture. Better medical flexibility could be achieved if doctors could specify particular accessories to be added after manufacture.

SUMMARY OF THE INVENTION

The present invention provides an accessory module for mounting accessories on an implantable fluid dispenser. A metallic case is sealed permanently to include a fluid reservoir, means for pumping the fluid, and outlet means to pass fluid to the exterior of the case. The case has a smooth biocompatible shape. It is generally curved to avoid irritation within the body. An indentation or shelf is set into this curved surface.

An accessory module, preferably of a biocompatible non-metallic material, is shaped to fit in the indentation or shelf so that, when it is in place, an accessory housing of the module completes the curve of the case and presents to the patient a smooth complete curved surface, which does not cause irritation.

The accessory housing has a fluid inlet means for coupling to the fluid outlet means on the case. It also has an accessory fluid outlet means to pass fluid from the accessory housing out to the body of the patient through an attached catheter.

In one embodiment, the accessory housing includes a filter for filtering fluid as it passes from the accessory inlet to the accessory outlet.

In another embodiment, the accessory housing includes a port to allow fluid to be directed into the accessory housing and into the attached catheter from outside the patient's body. In one example, the port is a septum for receiving a hypodermic needle. This allows direct injection from outside the body of the patient of fluid which would pass through the housing outlet into a catheter into the patient's body without interfacing with the sealed case.

A fluid dispensing device constructed according to the present invention allows great savings of manufacture in that various accessories can be added to the device after its manufacture. A doctor can specify a particular type of filter, or a particular type of port, or other accessory to be added on to a fluid dispensing device after its manufacture. In one embodiment, such devices can be added by the doctor at the site of implantation.

By separating accessories from the sealed case, the accessories can be separately tested. Testing filters, for example, within a sealed fluid dispensing device is extremely difficult. Filters can be separately tested in the present invention and later added for use in the patient.

This invention solves the prior art problems of bulky or loose devices added to the fluid dispensing device. The device retains the same smooth body-compatible curve to minimize irritation to tissue of the patient. The accessory devices are fixedly mounted on the sealed case in a location where they may be easily located by the physician. The greatest possible flexibility in combinations of accessory devices and economy is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fluid dispensing device with an accessory module mounted;

FIG. 2 is an enlarged fragmentary side elevational view of one embodiment of a first embodiment of the accessory module of FIG. 1;

FIG. 3 is a partially cross-sectional view, partially cut-away view taken online 3--3 of FIG. 2;

FIG. 4 is a fragmentary enlarged view of a second embodiment of the accessory module of FIG. 1;

FIG. 5 is a partially cross-sectional, partially cut-away view taken on line 5--5 of FIG. 4;

FIG. 6 is an enlarged fragmentary view of a third embodiment of the accessory module of FIG. 1;

FIG. 7 is a partially cross-sectional, partially cut-away view taken on line 7--7 of FIG. 6;

FIG. 8 is an enlarged fragmentary cross-sectional view taken online 8--8 of FIG. 6;

FIG. 9 is an enlarged fragmentary cross-sectional view taken on line 9--9 of FIG. 7; and

FIG. 10 is an enlarged fragmentary cross-sectional view taken online 10--10 of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Animplantable drug dispenser 20 is illustrated having a smooth exterior surface which minimizes irritation on human tissue when implanted. Theparticular dispenser 20 illustrated is shaped like a short cylinder, similar to a hockey puck with rounded edges.Drug dispenser 20 is provided with aninlet 22 for filling with a selected medication. In the example illustrated,inlet 22 is a septum which is pierced with a hypodermic needle inserted through the patient's skin.

Drug dispenser 20 includes a sealedcanister 24 and anaccessory housing 26. Canister 24 is preferably made of a biocompatible metal, such as titanium, which is welded to make a hermetically sealed enclosure for the fluid reservoir and mechanics of thedrug dispenser 20.Canister 24 is provided with anindentation 28 which is set in from the normally smooth shape ofcanister 24. In this case,indentation 28 is a shelf. In other embodiments,indentation 28 is a section removed from the shape ofcanister 24.Accessory housing 26 is shaped to mount inshelf 28, so that it blends into the smooth biocompatible outside curve ofcanister 24.

Accessory housing 26 1s preferably made of biocompatible, drug-compatible material, such as an inert plastic like polypropylene.

Anaccessory fluid outlet 30 is mounted onaccessory housing 26. A fluid-conveying catheter is mounted onaccessory fluid outlet 30 at the time of implantation.

In FIG. 1,accessory housing 26 is shown exploded away.

The enlarged fragmentary view of FIG. 2 shows a first embodiment of the accessory module of FIG. 1 which includes afilter 32.Canister 24 includes afluid outlet 34 which mates with anaccessory fluid inlet 36 inaccessory housing 26. Fluid passes out of a dispensing mechanism incanister 24 throughcanister fluid outlet 34,accessory fluid inlet 36 and passage 38 into afilter chamber 40 inaccessory housing 26. In the embodiment illustrated,filter chamber 40 is a generally rectangular opening. Afilter membrane 42 is mounted withinfilter chamber 40.

In one embodiment of this embodiment, the filter membrane is a hydrophyllic 0.1 micron pore-size bacterial/pyrogen retentive membrane. This membrane is constructed of an inert polymer such as nylon or PVDF to ensure long-term stability. In another embodiment, this filter membrane is a 50 micron pore-size membrane designed to filter larger particles and emboli. In another version of this embodiment, the filter membrane is partially hydrophyllic and partially hydrophobic to allow both drug and small gas bubbles to be filtered and to prevent any air lock.

In the embodiment illustrated,filter membrane 42 is rectangular. It extends across theentire filter chamber 40 so that fluid entering through passage 38 passes along one entire side offilter membrane 42 and must pass throughmembrane 42 to progress topassage 44, from where it passes out ofaccessory flu1d outlet 30. In this manner, all drug dispensed byfluid dispenser 20 is filtered byfilter membrane 42 before being dispensed in the body of the patient.

Accessory housing 26 is mounted oncanister shelf 28. A first mountingstud 46 oncanister 24, protrudes into a first mountinghole 48 inaccessory housing 26.

First mountingstud 46 is provided with a fixation slot 50 therethrough. A fixation access opening 52 is provided inaccessory housing 26 which is open to first fixation slot 50. Onceaccessory housing 26 is positioned onshelf 28 so that first mountinghole 48 accepts first mountingstud 46, a fixation wedge 54 is inserted throughfirst opening 52 into first fixation slot 50, thereby lockingaccessory housing 26 in place. In the illustrated embodiment,first opening 52 is then filled with plastic or adhesive material to hold first fixation wedge 54 in place.

Similarly, at an opposite end ofaccessory housing 26, asecond mounting stud 56 oncanister 24 is covered by a second mountinghole 58 inaccessory housing 26. Second mountingstud 56 has a second fixation slot 60 therethrough. Asecond opening 62 inaccessory housing 26 allows access from outside theaccessory housing 26 to second fixation slot 60. Asecond fixation wedge 64 is inserted throughsecond opening 62 into second fixation slot 60 to lockcanister 26 to second mountingstud 56.

Accessory housing 26 is provided with an additionalfilling inlet opening 66. In the embodiment illustrated, thedevice 20 is pressurized with a constant pressure fluid through fillinginlet 67. After the device is filled throughinlet 67, theinlet 67 is permanently sealed. Theinlet 67 projects slightly outside thecanister 24. This inlet is accepted into inlet opening 66 ascanister shelf 28 receivesaccessory housing 26.

The illustrated accessory housing is easily applied tocanister 24 at any point after manufacture. The filter in the embodiment illustrated in FIG. 2 can be installed in theplastic housing 26 and fully tested without interacting in any way with the mechanisms incanister 24. When the time for final assembly arrives, whether it be at the factory or in a hospital setting, ahousing 26 containing theappropriate filter membrane 42 is selected and mounted on first and second mounting pins 46 and 56.

A second embodiment of an accessory housing is illustrated in FIGS. 4 and 5. Accessory housing 80 mounts on first and second mounting pins 46 and 56 in a manner identical to the embodiment illustrated in FIGS. 2 and 3. In this embodiment, accessory fluid inlet 82 includes a check valve 84 to prevent back-flow of fluid from accessory housing 80 intocanister fluid outlet 34. Fluid received through accessory fluid inlet 82 passes through first passage 86 into aseptum chamber 88 located in accessory housing 80. Fromseptum chamber 88, fluid passes throughsecond passage 90 and out through accessoryfluid outlet 92 into the patient.Septum chamber 88 is accessible from outside ofaccessory housing 26 through piercible septum 94. This septum 94 operates in a manner similar toinlet 22 incanister 24. A hypodermic needle from outside the patient is inserted through the skin and through septum 94 intochamber 88. Fluid is then injected intochamber 88. Check valve 84 prevents back flow intocanister 24. This fluid immediately passes throughsecond passage 90 and outaccessory outlet 92.

In this manner, acute dosages of drug or diagnostic fluids are injected into the patient without employing the pumping apparatus ofcanister 24. The accessory housing 80 is fixedly mounted oncanister 24 and provides a smooth contour continuing the lines ofcanister 24. This fits well within the patient and prevents aggravation of surrounding tissue, yet provides additional acute drug access through septum 94. The prior art techniques of sharp or irregular projections from the device are avoided.

A third embodiment of the present invention is illustrated in FIGS. 6 and 7. This embodiment includes anaccessory housing 100 provided with afilter chamber 102 andfilter member 104 which operate in the manner of the embodiment illustrated in FIG. 2. Fluid is accepted through accessoryfluid inlet 106, passes through first passage 108 and intofilter chamber 102. After fluid passes throughfilter membrane 104 it proceeds throughsecond passage 110. Insecond passage 110 is a check valve 112, shown in schematic form, which allows fluid to pass only in one direction.Second passage 110 opens into septum chamber 114. Chamber 114 is subsequently open tothird passage 116 which empties intoaccessory outlet 118.

As in the embodiment illustrated in FIGS. 4 and 5, aseptum 120 allows access by a hypodermic needle to septum chamber 114. Acute infusions of fluid may be injected by a hypodermic needle into chamber 114 as in the earlier described embodiments. Check valve 112 prevents the acute infusion of fluid from proceeding backward intofilter chamber 102 orcanister 24.

In this embodiment,accessory housing 100 mounts onshelf 24 in a manner identical to earlier illustrated embodiments.

With the present invention, various combinations of external accessories can be easily added to an infusion device to tailor the device to the need of the particular patient. As illustrated, a filter, an infusion septum, combination thereof, or other accessory can be installed in this manner without requiring complex factory installation. The preferred embodiment of accessory module can easily be fabricated, such as by molding, from a biocompatible polymer such as polypropylene or a fluoropolymer at little expense. The accessories in the accessory housing can be independently tested without interfacing with the complexities of the apparatus within the infusion pump canister. If there are failures in tested devices, they can be discarded at low cost without involving the great expense of scrapping or repairing the sealed case.

The correct accessory for the type of drug to be adminstered is selected and mounted on the canister as needed. In some preferred embodiments, the accessory housing is mounted by the physician after selection of the proper accessories. Specific filters can be stocked for specific drugs or therapies. This increases the likelihood that the proper device will be available in a timely manner when needed by a patient for whom has been prescribed a particular therapy. The choice can be made for each patient whether to include a filter, an infusion port, or a combination of accessories. This greatly increases the flexibility of the device, in that the doctor can alter characteristics of the device by choosing proper accessories designed to maximize treatment for the patient.

When new drug therapies are discovered which require different accessories, the accessories can be manufactured and tested without expensive redesign of components within the hermetically sealed case.

While the present invention has been illustrated in terms of particular embodiments, it should be noted that the invention may take the form of other useful embodiments not illustrated herein.

Claims (13)

What is claimed is:

1. An implantable fluid dispensing device comprising:

a sealed case having a smooth biocompatible curved surface;

the case having an indentation inwardly diverging from the curved surface; and

an accessory housing shaped to mount on the case in the indentation and shaped to conform generally to the curved surface.

2. The device of cla1m 1 further comprising:

fluid outlet means in the case for passing fluid from inside the case to outside the case;

fluid inlet means in the accessory housing for coupling to the fluid outlet means on the case when the housing is mounted on the case; and

second fluid outlet means on the accessory housing for passing fluid from within the accessory housing into a patient's body.

3. The device of claim 2 further comprising filter means mounted in the accessory housing for filtering the fluid as it passes from the inlet means to the second outlet means.

4. The device of claim 2 further comprising:

port means on the accessory housing for receiving fluid to be passed through the accessory housing and out the second outlet means.

5. The device of claim 4 wherein the port means includes a pierceable septum for receiving fluid from a hypodermic needle inserted through skin of the patient.

6. An implantable fluid dispensing device comprising:

a sealed case having a fluid storage reservoir;

fluid outlet means on the case for passing fluid from the reservoir to the exterior of the case;

the case having a curved shape and having a shelf stepped in from the curved shape;

an accessory housing shaped to mount in the shelf and to conform generally to the external curved surface;

accessory fluid inlet means in the accessory housing for coupling to the fluid outlet means on the case and for passing fluid into the accessory housing;

filter outlet means in the accessory housing for passing fluid from the accessory housing into a patient's body; and

filter means mounted in the accessory housing for filtering fluid passing from the accessory fluid inlet to the accessory fluid outlet.

7. The device of claim 6 further comprising an inlet port in the accessory housing for receiving fluid from outside the patient's body.

8. The device of claim 7 wherein the inlet port includes a septum for receiving a hypodermic needle.

9. An implantable fluid dispensing device comprising:

a sealed case having a fluid storage reservoir;

fluid outlet means on the case for passing fluid from the reservoir to the exterior of the case;

the case being shaped with a biocompatible curved perimeter and having a shelf stepped in from the curved perimeter;

an accessory housing mounted on the shelf and shaped to conform to the curved perimeter;

an inlet port mounted on the accessory housing for injecting fluid into the housing; and

valve means for preventing fluid from the housing from passing into the sealed case.

10. The device of claim 9 further comprising filter means mounted in the accessory housing for filtering fluid as it passes through the accessory housing.

11. An accessory module for mounting on an implantable fluid dispensing device comprising:

an accessory housing formed of inert biocompatible plastic having one curved side shaped to contact the interior of the body in a non-irritating manner and a second side shaped to be inset in its fluid dispensing case;

accessory fluid inlet means mounted on the accessory housing for receiving fluid;

accessory outlet means mounted on the housing for dispensing fluid; and

an accessory mounted within the housing for processing fluid.

12. The device of claim 11 wherein the accessory is a filter for filtering fluid as it passes through the housing.

13. The device of claim 11 wherein the accessory is a port for receiving fluid from a source external to a patient's body and a valve for preventing flow of fluid out of the accessory inlet port.

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