Fill port for an implantable dispensing system

An implantable medication dispensing system includes an integral reservoir from which medicament is dispensed by a manually actuated micro-infusion pump system. Medicament is added to and removed from the reservoir as required through a liquid-sealed fill port having a integral needle-actuated safety valve. Upon introduction of the needle through a self-sealing septum, the safety valve is actuated open to allow medicament to be introduced and withdrawn by the needle. Upon removal of the needle the septum is closed by radial compression and the safety valve is actuated closed to prevent pressure flow through the fill port.

BACKGROUND OF THE INVENTION 
The present invention is directed generally to infusion systems, and more 
particularly to an implantable fill port having an internal 
needle-actuated safety valve for introducing medicament to a subcutaneous 
reservoir. 
Implanted manually-actuated micro-infusion pump systems are advantageously 
employed when specific dosages of a medicament are to be administered 
within the human body at various times over an extended time period, as in 
the treatment of diabetes and other diseases of the digestive system. 
In the treatment of diabetes a dispensing system comprising a combined pump 
and medicament reservoir system is subcutaneously implanted in soft tissue 
close to the delivery site, such as over the peritoneum and abdominal 
muscles, and a catheter is utilized to deliver insulin to the site. 
Alternatively, the reservoir is implanted remotely from the site and 
connected to a pump system by means of a flexible catheter. When insulin 
is required actuation of the pump system is accomplished by the patient 
applying pressure on the skin surface overlying the pump. 
Typically, medicament is added to the reservoir at periodic intervals 
through a fill port provided in the wall of the reservoir. A hypodermic 
needle is inserted through the skin so as to contact and puncture a 
needle, penetrable fluid impermeable membrane included in the port. All 
remaining medicament is then withdrawn, and a new known volume of 
medicament is introduced through the needle. 
One drawback of previous implantable fill ports was their susceptibility to 
leakage when fluid in the associated reservoir was subjected to an applied 
pressure. This problem became more pronounced with repeated use of the 
fill port, since repeated puncturing of the fill port septum by the 
hypodermic needle weakened or decreased the effectiveness of the sealing 
membrane. 
The present invention overcomes this problem by incorporating within the 
fill port an integral needle-actuated valve. Upon introduction of the 
needle through the septum of the port the valve is automatically opened to 
allow the addition or withdrawal of the medicament. Upon removal of the 
needle the valve automatically closes, and by reason of the construction 
of the valve increased pressure within the reservoir enhances the sealing 
properties of the valve. Also, in accordance with another aspect of the 
invention, the septum may be maintained under compression to preclude 
leakage through the septum upon removal of the needle. 
Accordingly, it is a general object of the present invention to provide a 
new and improved fill port for implantable dispensing systems. 
It is a more specific object of the present invention to provide a new and 
improved fill port which is less susceptible to leakage from internally 
applied medicament pressure. 
It is a more specific object of the present invention to provide a new and 
improved implantable fill port which opens upon introduction of a needle, 
and is automatically closed upon removal of the needle. 
SUMMARY OF THE INVENTION 
The present invention is directed to an implantable fill valve system for a 
fluid reservoir which includes a housing defining a valve chamber. A 
needle-penetrable fluid-impermeable membrane is disposed at one end of the 
chamber. Fluid communication between the valve chamber and the reservoir 
is established by a valve disposed for operative engagement with the 
needle upon the needle entering the port housing through the membrane to 
facilitate removal or introduction of medicament from the reservoir.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, and particularly to FIGS. 1-4, a fill port 
constructed in accordance with the invention may be advantageously 
utilized in an implantable combined pump and reservoir medicament 
dispensing system 10. As seen in FIG. 1, this dispensing system includes a 
generally disc shaped housing 11 within which pump, reservoir and fill 
port elements are contained, and a dispensing port 12 from which 
medicament is dispensed to an administration site by means of a flexible 
catheter 13 of conventional construction. The dispensing system 10 is 
preferably of compact construction for implantation with minimal distress 
to the human body. 
Referring to FIG. 3, housing 11 is seen to include a base portion 14, which 
may be formed of a hard biocompatible material such as plastic, and an 
overlying body portion 15, which may also be formed of a biocompatible 
material such as a similar plastic. The body portion defines a recess over 
which a flexible and expandable wall 16 of Dacron reinforced siliastic 
material is provided to form an internal reservoir 17 within which a 
volume of medicament is to be dispensed is stored. 
To provide for the reliable dispensing of accurate dosages of medicament 
from reservoir 17, dispensing system 10 includes a safety pump 20 and a 
metering pump 21. These pump components, which are manually actuated by 
the application of pressure to the exterior surface of the dispensing 
system, are interconnected within housing 11 by means of a fluid circuit 
22 such that upon actuation of safety pump 20 medicament (or other fluid 
in the reservoir of dispenser 10) passes from the reservoir to the 
metering pump 21. Then, upon actuation and release of the metering pump 21 
the medicament is dispensed through dispensing port 12 to the delivery 
site. The construction and operation of this pump system is described in 
the copending application of the present applicant entitled "Implantable 
Manually Operated Medication Dispensing System", Ser. No. 484,572 filed 
Apr. 13, 1983. 
Dispensing system 10 includes, in accordance with the invention, a fill 
port 23 through which medicament may be added to or removed from reservoir 
17. This fill port, which is positioned generally in the center of housing 
11 between the safety pump 20 and the metering pump 21, allows convenient 
subcutaneous fluid communication with reservoir 17 by means of a single 
needle, while providing reliable protection against pressure induced 
leakage from the reservoir. 
Basically, as shown in FIGS. 3 and 4, fill port 23 is formed in part by an 
aperture 30 in base member 14 of housing 11. A valve member 31 extends 
through this aperture and includes an annular valving surface which 
engages a valve seat formed by the aperture to control flow through the 
aperture. The valving member 31 is biased to a closed position by a 
helical spring 32 which bears against a valve actuator member 33 in 
mechanical engagement with valving member 31. An annular channel 34 is 
provided in base member 24 to receive the spring 32. An overlying 
needle-penetrable fluid-impermeable septum 35 formed of a bio-compatible 
rubber of silastic material is held in compressive engagement by the 
molded body portion 15 to provide a fluid-sealed chamber 36. An annular 
channel 37 may be formed around the inside perimeter of chamber 36 to 
assist in the sealing engagement, the interior diameter of the chamber 
across the channel preferably being less than the exterior diameter of 
septum 35 to maintain the septum in radial compression relative to its 
axis for improved fluid sealing. 
As shown in FIG. 4, fill port 23 is normally closed, the valve member 31 
being biased by spring 32 against the valve stop. Pressure exerted by the 
medicament in reservoir 17, as shown by the arrows, only serves to more 
firmly seat valve member 31, thereby preventing uncontrolled medicament 
flow through the fill port. The needle-penetrable septum 35, being held 
firmly in radial compression within the annular rim 37 of housing member 
15, further serves to maintain a liquid seal against fluids internal or 
external of the dispensing system 10. 
Referring to FIG. 5a, upon introduction of a needle 39 through septum 35, 
actuator member 33 is forced downwardly upon contact with the needle. This 
causes valve member 31 to be displaced from its valve seat, opening 
aperture 30 and establishing fluid communication between reservoir 17 and 
port chamber 36. 
Generally, prior to introducing new medicament, the remaining medicament 
within reservoir 17 is withdrawn through needle 39 to prepare the 
reservoir for receiving a new and known volume of medicament. After the 
medicament has been thus withdrawn from the reservoir, new medicament may 
be introduced through the same needle 39 (or through a different needle 
inserted through septum 35) until the reservoir has been refilled to the 
desired volume. 
The new medicament introduced through needle 39 enters the reservoir 
through aperture 30, as shown in FIG. 5b. The valve member 31 remains 
depressed by the force of needle 39 on actuator member 33. 
Upon completion of the filling procedure, needle 39 is removed. This allows 
spring 32 to return valve member 31 to its closed position, effectively 
closing aperture 30 to prevent further fluid flow into or out of reservoir 
17. At the same time, the compressive force exerted by housing member 15 
on septum 35 causes that component to reseal as the needle is withdrawn, 
so that an additional liquid-tight seal exists across the top surface of 
the fill port. 
It will be appreciated that the fill port of the invention, although shown 
in conjunction with a combined reservoir and pump medicament dispensing 
system, can be utilized in conjunction with virtually any implanted 
reservoir or catheter to permit the subcutaneous introduction of fluids. 
For example, the fill port of the invention may be utilized in conjunction 
with an implanted electrically actuated pump systems utilized for diabetes 
treatment. 
While a particular embodiment of the invention has been shown and 
described, it will be obvious to those skilled in the art that changes and 
modifications may be made therein without departing from the invention in 
its broader aspects, and therefore, the aim in the appended claims is to 
cover all such changes and modifications as fall within the true spirit 
and scope of the invention.