Catheter assembly
A catheter assembly includes: a catheter having an inner cavity extending along a center axis of the catheter, the catheter comprising, on a distal side, a tapered portion that is tapered in a distal direction; and an inner needle retractably located in the inner cavity. The inner needle comprises, on a distal side, a blade surface that is inclined with respect to a center axis of the inner needle. The tapered portion covers a proximal end portion of the blade surface in an assembled state in which the inner needle is located in the inner cavity, and an inner shape of a distal-most end of the tapered portion conforms to the blade surface.
1. A catheter assembly comprising:
a catheter having an inner cavity extending along a center axis of the catheter, the catheter comprising, on a distal side, a tapered portion that is tapered in a distal direction; and
an inner needle retractably located in the inner cavity;
wherein the inner needle comprises, on a distal side, a blade surface that is inclined with respect to a center axis of the inner needle;
wherein the tapered portion covers a proximal end portion of the blade surface in an assembled state in which the inner needle is located in the inner cavity, and an inner shape of a distal-most end of the tapered portion conforms to the blade surface;
wherein, in a cross section orthogonal to the center axis of the inner needle, an outer peripheral surface of the distal side of the inner needle comprises:
the blade surface, and
an arcuate surface; and
wherein in a cross section orthogonal to the center axis of the catheter in the assembled state, the tapered portion comprises:
a flat portion having an inner surface opposing the blade surface, and
an arcuate portion opposing the arcuate surface.
2. The catheter assembly according to claim 1 ,
wherein the distal-most end of the tapered portion is in contact with the outer peripheral surface of the inner needle, including at the blade surface.
3. The catheter assembly according to claim 1 ,
wherein the tapered portion comprises:
an outer flat surface on an outer surface side that corresponds to a circumferential position of the inner surface.
4. The catheter assembly according to claim 3 ,
wherein an inclination angle of the outer flat surface with respect to the blade surface is smaller than an inclination angle of a proximal side portion of the blade surface with respect to the center axis of the inner needle.
5. The catheter assembly according to claim 3 , wherein:
in the cross section orthogonal to the center axis of the inner needle, the outer peripheral surface of the distal side of the inner needle comprises:
a rounded corner surface joining the blade surface with the arcuate surface, the rounded corner surface having a larger curvature than the arcuate surface; and
in the cross section orthogonal to the center axis of the catheter in the assembled state, the tapered portion comprises:
a rounded corner portion joining the flat portion with the arcuate portion, the rounded corner portion opposing the rounded corner surface.
6. The catheter assembly according to claim 1 , wherein:
the inner needle has a needle hole extending along the center axis of the inner needle, and the blade surface includes a needle tip opening communicating with the needle hole; and
the tapered portion covers a proximal end portion of the needle tip opening.
7. The catheter assembly according to claim 1 , wherein:
the blade surface includes a first area having a distal end configured to form a cut, and a second area that is continuous with a proximal end of the first area and is configured to widen the cut; and
the tapered portion partially covers the second area without covering the first area in the assembled state.
8. The catheter assembly according to claim 1 ,
wherein the catheter is formed of a material comprising polyurethane.
9. A method of making a catheter assembly comprising:
providing a catheter having an inner cavity extending along a center axis of the catheter, the catheter comprising, on a distal side, a tapered portion that is tapered in a distal direction; and
inserting an inner needle into the inner cavity;
wherein the inner needle comprises, on a distal side, a blade surface that is inclined with respect to a center axis of the inner needle;
wherein, after the inner needle is inserted into the inner cavity, the tapered portion covers a proximal end portion of the blade surface in an assembled state in which the inner needle is located in the inner cavity, and an inner shape of a distal-most end of the tapered portion conforms to the blade surface; and
wherein, in a cross section orthogonal to the center axis of the inner needle, an outer peripheral surface of the distal side of the inner needle comprises:
the blade surface, and
an arcuate surface; and
wherein in a cross section orthogonal to the center axis of the catheter in the assembled state, the tapered portion comprises:
a flat portion having an inner surface opposing the blade surface, and
an arcuate portion opposing the arcuate surface.
10. The method according to claim 9 , wherein the step of providing the catheter comprises, before inserting the inner needle into the catheter, heating the catheter to form the tapered portion.
11. The method according to claim 9 ,
wherein, after the inner needle is inserted into the inner cavity, the distal-most end of the tapered portion is in contact with the outer peripheral surface of the inner needle, including at the blade surface.
12. The method according to claim 9 ,
wherein the tapered portion comprises:
an outer flat surface on an outer surface side that corresponds to a circumferential position of the inner surface.
13. The method according to claim 12 ,
wherein an inclination angle of the outer flat surface with respect to the blade surface is smaller than an inclination angle of a proximal side portion of the blade surface with respect to the center axis of the inner needle.
14. The method according to claim 12 , wherein:
in the cross section orthogonal to the center axis of the inner needle, the outer peripheral surface of the distal side of the inner needle comprises:
a rounded corner surface joining the blade surface with the arcuate surface, the rounded corner surface having a larger curvature than the arcuate surface; and
in the cross section orthogonal to the center axis of the catheter in the assembled state, the tapered portion comprises:
a rounded corner portion joining the flat portion with the arcuate portion, the rounded corner portion opposing the rounded corner surface.
15. The method according to claim 14 ,
wherein the step of providing the catheter comprises, before inserting the inner needle into the catheter, shaping the flat portion, the arcuate portion and the rounded corner portion.
16. The method according to claim 9 , wherein:
the inner needle has a needle hole extending along the center axis of the inner needle, and the blade surface includes a needle tip opening communicating with the needle hole; and
the tapered portion covers a proximal end portion of the needle tip opening.
17. The method according to claim 9 , wherein:
the blade surface includes a first area having a distal end configured to form a cut, and a second area that is continuous with a proximal end of the first area and is configured to widen the cut; and
the tapered portion partially covers the second area without covering the first area in the assembled state.
18. The method according to claim 9 ,
wherein the catheter is formed of a material comprising polyurethane.