High flow rate dialysis catheters and related methods
View Patent ↗High flow rate catheters, and related methods, are useful in dialysis and other procedures. A catheter according to the invention comprises a hub and a generally elongated conduit. The conduit has a substantially continuous and smooth wall. The conduit also defines at least one lumen and has a length extending from a proximal end to a distal end of the conduit. The proximal end is coupled to a hub and the distal end has an opening in communication with the lumen. The conduit has a conical shape which tapers along the length.
1. A method of making a catheter comprising:
extruding a generally elongated conduit wherein the conduit is formed by being pushed through a die at an extrusion rate while being pulled from the die at a pulling rate,
after the method is completed, the catheter comprising an end product in which the conduit includes an outer wall, the conduit defining at least two lumens, the conduit being formed so that a thickness of the outer wall smoothly increases from a first end to a second end of a transition zone of the conduit and so that a cross-sectional area of each of two of the at least two lumens increases from the first end to the second end of the transition zone, wherein an internal divider is formed so that a thickness of the internal divider increases from the first end to the second end of the transition zone of the conduit.
2. The method of claim 1 wherein during at least a portion of a time during which the extrusion is occurring, the extrusion rate is the same as the pulling rate.
3. The method of claim 1 wherein during at least a portion of a time during which the extrusion is occurring, the extrusion rate is different than the pulling rate.
4. The method of claim 3 wherein the extrusion rate is different from the pulling rate during the entire time during which the extrusion is occurring.
5. The method of claim 1 further comprising cooling the conduit as it is pulled from the die.
6. The method of claim 1 further comprising applying a pressurized gas to the material being extruded to form at least one of the at least two lumens.
7. The method of claim 1 wherein an end of the conduit comprises an opening in communication with at least one of the at least two lumens.
8. The method of claim 1 wherein the pulling and extrusion rates are controlled relative to one another to achieve a desired tapering in wall thickness and lumen size.
9. The method of claim 1 wherein the pulling and extrusion rates are controlled relative to one another to form a first cylindrical section of the conduit extending from a first point to a second point, a frusto-conical section of the conduit extending from the second point to a third point, and a second cylindrical section of the conduit extending from the third point to a fourth point.
10. The method of claim 9 wherein the frusto-conical section comprises a smaller cross-sectional area at the third point than at the second point.
11. The method of claim 9 wherein the thickness of the outer wall increases from the third point to the second point.
12. The method of claim 9 wherein a cross-sectional area of at least one of the at least two lumens increases from the third point to the second point.