Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-04-30
2001-09-04
Nguyen, Anhtuan T. (Department: 3734)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S142000, C604S183000, C604S891100
Reexamination Certificate
active
06283944
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to drug delivery devices for delivering drugs to the body of a patient. More particularly, the present invention relates an implantable drug infusion system that delivers a fixed flow of drug and permits patient control of additional drug dosage.
BACKGROUND OF THE INVENTION
The use of implantable drug infusion systems is well-known. These systems provide steady, long-term delivery of drug therapy to the human body. They also eliminate the need for frequent intravenous drug injections. Each system typically includes a refillable drug reservoir and flow control device for regulating the drug delivery rate.
One form of drug infusion system incorporates an implantable pump such as that disclosed in U.S. Pat. Nos. 5,445,616 and 5,575,770. The subject matter of both patents is incorporated herein by reference. Pump-based systems provide constant flow of drug to the patient at very low rates. These pumps may be fixed rate pumps or programmable pumps. In the case of fixed-rate, adjustment of the delivery rate and therefore the drug dosage may not be altered. In case of programmable pumps, reprogramming of the pump controller by a physician is required for changes in pump rate.
There is a current trend towards providing some degree of patient control in implantable drug infusion systems. Clinical studies show that actual drug usage may be reduced if a patient believes that he or she has some degree of control over drug dosage. A terminally-ill patient who has no ability to control or self-administer a drug will frequently insist on additional dosage at each visit to a physician as a precaution against exhaustion of the drug supply before the patient's next office visit. In addition to these patient psychological aspects, there are added benefits of patient control. For example, in progressive diseases, the development of breakthrough pain may require immediate increase in drug dosage. Similarly, a diabetic patient may need to tailor insulin dosage to maintain blood glucose levels through a changing diet. The ability to self-administer drug therapy may therefore reduce the number of office visits and provide immediate drug dosage increase when needed.
There have been prior efforts to provide drug infusion systems that offer patient controlled dosage features. One known form of drug infusion system which includes patient controlled dosage features is a drug infusion pad, such as that disclosed in U.S. Pat. No. 5,085,644, which permits a patient to self-administer drug therapy. Typically, this patient control of dosage is in the form of a deformable chamber which may be compressed by the patient to deliver an intermittent supply of drug to the body. The infusion pad is implanted subcutaneously, usually over the rib cage to provide support against the forces of a patient's fingers compressing the reservoir. Known drug infusion pads, however, only provide for intermittent delivery of drug therapy and are therefore undesirable in applications where a steady flow of drug is desired. The patient must continuously activate the infusion pad to receive medication. For example, U.S. Pat. No. 5,085,644 discloses a patient-controlled infusion device which utilizes a deformable pumping chamber to permit a patient to intermittently administer a supply of drug from a main reservoir. The disclosed device utilizes a fluid flow restrictor to limit the recharge rate of the pumping chamber.
There is a yet unaddressed need in the medical field for a drug infusion system which offers the benefits of both fixed-rate delivery systems and patient control of dosage. Such a system would find application in therapy delivery for example, for cancer patients, who may need a fixed rate of drug delivered constantly and the ability to administer themselves a bolus of drug when “breakthrough” pain occurs. Similarly, a diabetic patient may need, in addition to a steady supply of insulin, an additional dosage when the patient's diet has resulted in a lower than anticipated blood glucose level.
It would therefore be desirable to provide a drug infusion system which provides patient-control features in addition to the advantages offered by fixed rate delivery systems.
SUMMARY OF THE INVENTION
The invention provides an infusion system that delivers drug to the patient at a fixed rate and permits the patient to introduce a controlled bolus dosage when needed. In one preferred embodiment, the invention resides in a pump having a bulkhead that is provided with first and second flow paths from the pump reservoir to a single outlet port. The first flow path communicates with a first flow regulator which restricts flow in the first flow path to the desired fixed rate of delivery. The second flow path communicates with a patient-operated pumping device incorporated into the pump housing. The patient-operated pumping device may be in the form of a deformable reservoir that accumulates a drug bolus which may be expelled when the reservoir is compressed by the patient's fingers. A second flow regulator may be incorporated in the drug flow path upstream of the patient-operated pumping device to restrict the dosage that may accumulate therein. A safety valve may also be incorporated into the pump housing in downstream fluid communication with the patient-operated pumping device to prevent accidental discharge of the drug bolus.
In another preferred embodiment, the invention resides in a fluid control assembly that may be used with single or dual port pumps. The fluid control assembly comprises a body with an inlet port and an outlet port. Two fluid control paths are defined within the body between the ports. A first fluid control path is provided with a first flow regulator for regulating a fixed flow rate of drug between the inlet and outlet ports. A second fluid control path is in fluid communication with a patient-controlled pumping device which accommodates a bolus of drug that may be expelled by the patient. Both first and second fluid control paths communicate with the inlet port and outlet port. A second flow regulator is disposed in the second flow path to limit the rate of accumulation of the drug bolus. The reservoir communicates with the flow controller outlet port via a safety valve which prevents accidental discharge of the drug bolus.
Advantageously, the invention provides an infusion system that offers both a fixed rate of delivery and the capability for a patient to deliver a drug bolus when needed within safe dosage levels. Other objects, advantages novel features, and the further scope of applicability of the present invention will be set forth in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
REFERENCES:
patent: 4714462 (1987-12-01), DiDomenico
patent: 5085644 (1992-02-01), Watson et al.
patent: 5152753 (1992-10-01), Laguette et al.
patent: 5445616 (1995-08-01), Kratoska et al.
patent: 5505707 (1996-04-01), Manzie et al.
patent: 5575770 (1996-11-01), Melsky et al.
patent: 5607418 (1997-03-01), Arzbaecher
patent: 9012609 (1990-01-01), None
patent: 9723252 (1997-03-01), None
PCT International Search Report.
A1 Medtronic Brochure © 1996, AlgoMed Infusion System Model 84112, Pain Relief at Their Fingertips.
Gardner Anthony
Kratoska Paul
McMullen Ray
Banner & Witcoff , Ltd.
Medtronic Inc.
Nguyen Anhtuan T.
Thompson Michael M.
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