Percutaneous access device with removable tube

Claim 1

In a percutaneous access device for long-term implantation in humans and animals including a button having a skirt, a neck substantially normal to said skirt and having an upper portion and a lower portion, and a porous bed attached to and surrounding at least said lower portion of said neck and a portion of said skirt, said neck and skirt having a bore therethrough to accommodate a catheter tube, the improvement wherein said neck is shaped to form a tapered cavity in said bore, and said device further comprises lock means for releasably locking a catheter tube within the bore of said neck such that the tube may be inserted and replaced with out removal of said percutaneous access device from an implanted position and without any substantial disturbance to skin and tissue near said device, said lock means including a flexible seal of elastomeric material shaped to fit within said tapered cavity and to encircle a portion of said catheter tube and including a cap having a hole therethrough to accommodate said tube, said cap attachable to said neck and adapted to compress the seal against said tube and neck; the upper portion of said neck including means for receiving a tool to hold said neck in a generally stationary position during locking and release of said tube; and wherein said porous bed comprises a first stage extending along at least a lower portion of said neck and along a portion of said skirt adjacent to said neck, and a second stage overlying a portion of said skirt and forming a junction with one end of said first stage, said first stage having pores smaller than the pores of said second stage, and the pore sizes of said stages and the path length of said first stage along said neck and said skirt being selected such that upon implantation of said skirt in subcutaneous tissue, said first stage permits a controlled rate of epidermal cell downgrowth and said second stage permits the formation of mature collagen near the junction between said first and second stages substantially prior to the time epidermal cell downgrowth reaches said junction, whereby said epidermal cell downgrowth is halted near said junction and a tight, biologic seal is formed between said device and adjoining tissue near said junction.