This invention relates to devices for injecting or withdrawing fluid at predetermined regions of the body, and more particularly to a novel self-sealing subcutaneous infusion and withdrawal device.
Prosthetic devices are often implanted in the body to restore shapes and contours that have been surgically altered or accidentally deformed. Many prostheses maintain their desired shape or contour by absorbing or storing fluid that is specially introduced into the prosthesis from an external source. In addition it is often necessary to periodically vary the volume of fluid within the prosthesis to restore proper pocket tension or to modify the shape or contour of the prosthesis.
Rather than inject fluid directly into a prosthesis it has been found beneficial to infuse the fluid into a fluid transfer or dispensing device such as a septum which directs the fluid to its intended site. Preferably the septum is also implanted in the body to facilitate fluid replacement with minimum discomfort to the recipient.
One known device for administering fluid to a patient as disclosed in U.S. Pat. No. 4,543,088, comprises an elastomeric housing that defines an inner fill chamber. Except for the base, the housing walls can be penetrated on all sides by a needle. Consequently, the needle that enters one side of the housing for filling or withdrawal purposes can pass through another side of the housing, completely bypassing the fill chamber. Since this device is used subcutaneously there is no way of observing whether an injection of fluid is being received in the fill chamber or is bypassing said chamber because the needle has passed through the housing wall.
A transcutaneous device used for dialysis, as shown in U.S. Pat. No. 4,490,137, discloses a rigid metallic reservoir that makes direct contact with the body tissue upon implantation. The disclosed device includes a tube formed of separate individual interconnected sections that can leak at the connection seams. Furthermore, the unyielding structure of the metallic reservoir can cause discomfort upon implantation. The device also includes a needle penetrable surface that is not self sealing. Consequently, upon withdrawal of the needle, a fluid path can be established causing leakage. There is also a possibility of reflux back along the surface of the needle during injection.
It is thus desirable to provide a subcutaneous self-sealing infusing and withdrawal device that can be comfortably implanted, is not subject to leakage and minimizes the possibility of a needle passing into and out of the fluid chamber.