Pipes and tubular conduits – Plural duct – Longitudinally extending common wall
Reexamination Certificate
2001-03-16
2003-12-09
Hook, James (Department: 3752)
Pipes and tubular conduits
Plural duct
Longitudinally extending common wall
C138S117000, C604S029000, C604S027000, C604S043000, C604S093010, C604S264000, C604S284000
Reexamination Certificate
active
06659134
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to medical catheters and to peritoneal dialysis catheters in particular.
2. Background Information
The foldable peritoneal dialysis catheter as disclosed in U.S. Pat. No. 5,322,519 (“the Ash catheter”) represented a substantial advance in peritoneal catheter design and technology. However, the design of the Ash catheter leaves certain characteristics of the ideal peritoneal dialysis catheter lacking.
The only feasible embodiments of the Ash catheter invention or those designed for inflow or outflow, but not both. Ash does teach the basic concept of a peritoneal dialysis catheter for continuous use (Column 4, lines 54 et seq.), in other words, one which includes separate conduits for simultaneous inflow and outflow. However, Ash fails to provide an actual, workable design.
Ash's FIG. 4 depicts a proposed design for a continuous use peritoneal catheter, but one which simply cannot be made when existing technology is applied to the silicone material from which such catheters must be made. For example, Ash's septum 128 must, in order to be operative, form a fluid seal with the inner wall of housing 122. Even if this were possible to achieve in the manufacturing process (which experts in the silicone extrusion and manufacturing industry indicate it is not), the resulting catheter would be too rigid (because of the added rigidity of such 128) to be suitable for implantation. In addition, the T-configuration shown for this embodiment would, in actual application, causes accumulation of biological debris (and ultimately clogging) near the 90 degree bends in the conduits.
Ash's alternative continuous dialysis catheter design (shown in Ash's FIG. 8) is also a non-viable design suggestion. Merely conjoining two parallel conduits (Ash's “plenum chambers” 146 and 148) creates a cross-sectional footprint (other than substantially circular) which is not suitable for passage through, and long-term residence in the abdominal wall because of increased propensity for leakage, bacterial invasion, etc.
It would well serve those who administer and those who receive peritoneal dialysis to provide a viable design for a continuous use peritoneal dialysis catheter—one which provides all the benefits of the viable embodiments of the Ash single direction flow catheter, but goes farther in satisfying the remaining, unfulfilled objectives for an Ash-like catheter for continuous dialysis use.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved peritoneal dialysis catheter.
It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use (allowing simultaneous inflow and outflow).
It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use, and which is of a design which can feasiblely be manufactured using available manufacturing technology and methods.
It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use, it presents an ideal, circular cross-sectional contour of portions of such catheter as pass through and reside in the abdominal wall of a recipient.
It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use, and which is of a design which minimizes the chances of conduit occlusion because of highly angular diversions of the conduits.
In satisfaction of these and related objects, the present invention provides an improved peritoneal dialysis catheter which, because of seemingly minor, but highly significant modifications from prior art designs, is unique in its manufacturerability and its capacity to serve as continuous use peritoneal dialysis catheter without undue patient complications.
The peritoneal dialysis catheter design of the present invention, in the preferred embodiments, utilizes linearly mated conduits for that portion of the catheter which passes through the patient's abdominal wall (the trans-abdominal segment) and which cooperatively defined a substantially circular cross-sectional footprint. This feature provides the optimum cross-sectional footprint for lessening the likelihood of leakage and infection. Also, the present design avoids using a T-joint configuration as the transition from the trans-abdominal wall segment the catheter to the peripheral fluid transport branches which reside within a patient's abdomen—such a T-joint configuration creating a propensity for clogging near the angular conduit deviations, as well as creating excessive bulk which impedes implantation. Rather, the design of the present invention, because of the nested conduit design which lacks a septum has taught by Ash, is capable of actual manufacture, allows for the aforementioned circular cross-section for the trans-abdominal wall segment, and permits the transition from the trans-abdominal wall segment to the fluid transport branches of the catheter to proceed along a non-angular path.
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Henry David G.
Hook James
Navis John
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