Catheter introducing instrument

Claim 2

An instrument for introducing a catheter into a blood vessel, comprising: an inner needle portion including an inner needle having a tip formed to include a cutting edge; and a dilator portion having a hollow dilator with a tip for enabling said inner needle to be passed therethrough until the cutting edge of said inner needle projects from the tip of said dilator; said dilator comprising a primary insertion portion having a prescribed outer diameter, a secondary insertion portion having an outer diameter larger than that of said primary insertion portion, and an intermediate tapered segment smoothly interconnecting said primary and secondary insertion portions; said primary insertion portion extending from the tip of said dilator to one end of said tapered segment over a length no less than a distance from a skin surface to a wall of the blood vessel; said secondary insertion portion extending from another end of said tapered segment over a length no less than the distance from the skin surface to the wall of the blood vessel.

Claim 3

The instrument according to claim 1, wherein said primary and secondary insertion portions each have a length of no less than 15 mm.

Claim 4

The instrument according to claim 1 or claim 2, wherein the outer diameter of said secondary insertion portion is 1.3 to 3 times the outer diameter of said primary insertion portion.

Claim 5

The instrument according to any one of claims 1 to 3, wherein said first insertion portion has a wall thickness of 0.05 to 0.3 mm, and said second insertion portion has a wall thickness of no less than 0.3 mm.

Claim 6

The instrument according to any one of claims 1 to 4, wherein said primary insertion portion is made of a flexible and elastic material.

Claim 7

The instrument according to any one of claims 1 to 5, wherein said inner surface of the dilator is coated with a thrombus preventing material.

Claim 8

An instrument for introducing a catheter into a blood vessel, comprising: an inner needle portion including an inner needle having a tip formed to include a cutting edge; a dilator portion having a hollow dilator with a tip for enabling said inner needle to be passed therethrough until the cutting edge of said inner needle projects from the tip of said dilator; and said dilator comprising a primary insertion portion having a prescribed outer diameter, a secondary insertion portion having an outer diameter larger than that of said primary insertion portion, and an intermediate tapered segment smoothly interconnecting said primary and secondary insertion portions; a sheath portion comprising a sheath for enabling said dilator to be passed therethrough, the sheath being so adapted that when the dilator is passed therethrough, a tip of the sheath portion in proximity to an end of a secondary insertion portion of the dilator, and a valve body for enabling a catheter to be passed therethough under liquid-tight conditions; said primary insertion portion extending from the tip of said dilator to one end of said tapered segment over a length no less than a distance from a skin surface to a wall of the blood vessel; said secondary insertion portion extending from another end of said tapered segment over a length no less than the distance from the skin surface to the wall of the blood vessel.

Claim 9

An instrument for introducing a catheter into a blood vessel, comprising: an inner needle portion including an inner needle having a tip formed to include a cutting edge; a dilator portion having a hollow dilator with a tip for enabling said inner needle to be passed therethrough until the cutting edge of said inner needle projects from the tip of said dilator; and said dilator comprising a primary insertion portion having a prescribed outer diameter, a secondary insertion portion having an outer diameter larger than that of said primary insertion portion, and an intermediate tapered segment smoothly interconnecting said primary and secondary insertion portions; a sheath portion comprising a sheath for enabling said dilator to be passed therethrough, the sheath being so adapted that when the dilator is passed therethrough, a tip of the sheath portion in proximity to an end of a secondary insertion portion of the dilator, and a valve body for enabling a catheter to be passed therethough under liquid-tight conditions; said primary insertion portion extending from the tip of said dilator to one end of said tapered segment over a length no less than a distance from a skin surface to a wall of the blood vessel; said secondary insertion portion extending from another end of said tapered segment over a length no less than the distance from the skin surface to the wall of the blood vessel.

Claim 10

The instrument according to claim 7, wherein said primary and secondary insertion portions each have a length of no less than 15 mm.

Claim 11

.. The instrument according to claim 7 or claim 8, wherein the outer diameter of said secondary insertion portion is 1.3 to 3 times the outer diameter of said primary insertion portion.

Claim 12

The instrument according to any one of claims 7 to 9, wherein said first insertion portion has a wall thickness of 0.05 to 0.3 mm, and said second insertion portion has a wall thickness of no less than 0.3 mm.

Claim 13

The instrument according to any one of claims 7 to 10, wherein said valve body consists of a flexible, elastic material and has a first end face provided with an elongated first incision and a second end face provided with an elongated second incision, said first and second incisions being formed so as to intersect each other internally of said valve body without passing entirely therethrough.

Claim 14

The instrument according to claim 7, wherein said sheath portion further comprises a housing for fixedly retaining a base end portion of said sheath.

Claim 15

The instrument according to claim 12, wherein said housing internally accommodates said valve body in the vicinity of the base end portion of said sheath.

Claim 16

The instrument according to any one of claims 7 to 13, wherein said primary insertion portion is made of a flexible and elastic material.

Claim 17

The instrument according to any one of claims 7 to 14, wherein said inner surface of the dilator is coated with a thrombus preventing material.