Infusion pump with access regulator

Details Infusion pump with access regulator Infusion pump with access regulator

2002-03-22

2004-10-19

Chin, Christopher L. (Department: 1641)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S131000, C604S093010

Reexamination Certificate

active

06805687

ABSTRACT:

BACKGROUND
This invention relates to implantable infusion pumps, and more particularly to implantable infusion pumps in which access to drug reservoirs within the pump is controlled.
Implantable infusion pumps are used for the continuous delivery of medicaments, e.g. morphine in a constant dosage over long periods of time. Compared with conventional injections they have the advantage that there is no longer any need to provide an initial high dosage so that despite the decomposition of the medicament up to the next administration time, there is no drop below a certain minimum dose. Instead it is possible to achieve a uniform and significantly reduced supply of the medicament.
The pumps are implanted underneath the skin and are typically designed to be refilled by injecting medication into a reservoir in the pump, the injection penetrating the skin and a septa covering a port into the reservoir. Frequently, the pumps comprise more than one access port. A first access port supplies a reservoir containing medication for long term, slow delivery. A second access port supplies a reservoir which provides a bolus administration of the medication. Typically, all of the medication injected into the second port will be immediately infused into the patient. Incorrect administration of medicine intended for the first port into the second port will provide an overdose of medicine to the patient.
U.S. Pat. No. 5,395,324 solves this problem by providing one or more of the ports with a needle stop and filling the port with needles having a side outlet that is blocked unless inserted into the port to the correct depth by abutting the needle stop. Insertion into the wrong port blocks the outlet and prevents injection.
In addition to the problem of potentially injecting medicine into the wrong port, some patients have highlighted another problem. Especially with medications having an abuse potential, such as morphine, patients have been known to use a syringe to extract the medication from the long term reservoir and then self administer a large dose of the medicine. Such behavior can also lead to an overdose of medicine. The system of the aforementioned '324 patent hinders, but does not completely prevent, such action.
SUMMARY OF THE INVENTION
An implantable infusion pump according to the present invention provides for infusing medication into a patient. The pump comprises a reservoir for containing the medication and an injection access port into the reservoir. An openable and closable shield at the access port blocks access of an injection needle into the port when closed and allows access of the injection needle into the port when open.
The shield can be for instance adapted to move laterally with respect to the access port, or vertically with respect to the access port. Multiple shields can be employed to block access to the port and in addition the shield or shields can employ linear, rotational or other appropriate movement to block an unblock access to the port.
To operate the shield, a magnetic rotor can be provided within the pump coupled to the shield. A magnetic driver external of the pump magnetically couples to the rotor whereby to turn the rotor and operate the shield. The rotor preferably has a sequence of north and south magnetic poles and the driver a complementary sequence of magnetic poles. The sequence of poles can be irregular whereby to make unauthorized access to the pump more difficult. The poles on the driver can be electromagnets.
In one aspect of the invention, a controller can be provided which is in RF communication with a means for opening and closing the shield.
One desirable feature comprises a delay closing mechanism for automatically closing the shield some time period after it is opened so that an operator does not need to remember to close the shield.
A method according to the present invention restricts access to a drug reservoir in an implanted infusion pump which is accessible through an access port. The method comprises the steps of: shielding the access port with a shield during a time when access to the reservoir is not to be allowed; and moving the shield to allow access to the port during a time when access to the reservoir is to be allowed.


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Partial European Search Report, EP 03 25 1772, Jun. 11, 2003.

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