JP2531583Y2 - Catheter with soft tip at tip - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catheter having a soft tip at a distal end.

[0002]

2. Description of the Related Art Generally, catheters are inserted into blood vessels (particularly coronary arteries), trachea, fallopian tubes, ureters and various organs.
It is used for the purpose of injecting / suctioning liquid or securing the patency of a passage.

As is well known, it is convenient for smooth insertion into the body that the distal end on the insertion side of the catheter has appropriate rigidity, and conversely, after insertion into the body, it has appropriate flexibility. Is preferred because it is difficult to damage the cell tissue of blood vessels and organs.

[0004]

In order to avoid damage to cell tissues such as blood vessels after insertion into the body, polyurethane tip, as shown in FIG. A catheter is provided in which a soft tip 12 made of a polyolefin-based hydrocarbon or the like is joined by means such as heat fusion.

Although such a catheter has been developed to achieve the above object, the soft tip 12 is actually too flexible to secure the ease of insertion. There is a problem that the tip is caught by the cell tissue during the insertion and the insertability is poor. In addition, after insertion, the soft tip 12 still has insufficient flexibility, and thus has a problem that cell tissues such as blood vessels are easily damaged.

Accordingly, it is an object of the present invention to provide a catheter which overcomes the disadvantages of a conventional catheter having a soft tip.

[0007]

In order to achieve the above object, the catheter of the present invention is provided with a soft tip at the distal end, which is mainly composed of a polymer having a glass transition temperature (Tg) at or near body temperature. It is characterized by having.

Accordingly, the catheter of the present invention is easy to insert since the soft tip is in an environment of a body temperature or lower (room temperature) and has an appropriate rigidity before being inserted into the body. After insertion into the body, the chip is heated by body temperature, and the constituent polymer of the chip reaches the rubber region from the glass region and exhibits rubber-like elasticity, so that the flexibility is further improved and the in-vivo cell tissue is hardly damaged.

[0009] Thus, the soft tip is composed mainly of a polymer having a glass transition temperature within the body temperature of the insertion target or a temperature in the vicinity thereof.

The catheter of the present invention is applicable to mammals including human beings (eg, cows, rabbits, horses, sheep, monkeys, dogs, cats, etc.). Therefore,
In the present invention, the body temperature means the body temperature of each of these animals, and the temperature differs depending on the animal species.

In the present invention, the glass transition temperature is determined by JI
SK7121-1987 "Determination method of transition temperature of plastic" based on differential scanning calorimetry.
It is a value measured in an N ₂ gas atmosphere at ° C./min. In addition,
In this measurement method, for a material having two or more absorption peaks, the glass transition point is defined as the lowest temperature among the absorption peaks at which sufficient flexibility is exhibited.

In general, when many polymers are heated, the elastic modulus gradually decreases and the flexibility starts to increase from about several tens of degrees below the glass transition temperature. Examples of the material of the soft tip in the present invention, when the body temperature of the inserted target _{t 0, (t 0 -15)} ~ (t 0 +15) ℃, preferably _{(t 0 -7) ~ (t} 0 +7) ° C., particularly preferably those having a _{(t 0 -5) ~ (t} 0 +3) glass transition temperature in the range of ° C.. For example, when the subject is a human, the average body temperature is 21.5 to 51.5 ° C., preferably 29.5 to 43.5 ° C., particularly preferably 31.5 to 39.5 ° C. when the average body temperature is 36.5 ° C.

If the material constituting the chip has a glass transition temperature lower than (t ₀ -15) ° C., the modulus of elasticity is already too low at room temperature, making it difficult to insert the material into the body. On the other hand, when the temperature is higher than (t ₀ +15) ° C., the elastic modulus does not sufficiently decrease even when heated by body temperature, and there is a risk of damaging blood vessel walls in the body.

However, as a constituent material of the chip, the glass transition temperature is in the above-mentioned range, and 0.01 to 50 kgf / mm ² , especially when heated to the body temperature to be inserted.
Those which maintain an elastic modulus of 0.1 to 10 kgf / mm ² are preferred.

Examples of the polymer constituting the soft tip include polyvinyl chloride, polyurethane, ethylene vinyl acetate, styrene / butadiene rubber, polyethylene, polystyrene, SEBS, and the like. These are used to form the soft tip by conventional means.

A solution type material formed by drying a solution in which a polymer such as a polyurethane is dissolved in a solvent and removing the solvent, or a polyurethane or the like formed by mixing and polymerizing two liquid monomers and forming the mixture. The tip of the catheter can be instantaneously coated with a soft tip by immersing the tip of the catheter in these solutions using a liquid-mixing type material. According to this method, not only the formation of the soft tip is easy, but also the surface of the tip can be made flexible without significantly lowering the modulus of elasticity of the tip compared to before forming the tip. It is.

The manner in which the soft tip is provided at the distal end of the catheter is not particularly limited. For example, as shown in the related art, a tip is bonded to the tip by heat fusion, bonding, or the like (see FIG. 2), or the surface of the tip is covered with a soft tip.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the catheter of the present invention will be described based on embodiments. The catheter shown in FIG. 1 has the soft tip 2 provided so as to cover the surface of the distal end portion 1.

Examples 1 to 3 and Comparative Example 1 As an example, a soft tip was prepared by using a polymer as described above, and this was bonded to the surface of the distal end portion of the catheter by adhesion as shown in FIG.

In Comparative Example 1, a soft tip made of an ordinary polymer was bonded to the distal end portion of a catheter by heat fusion as shown in FIG.

In each of the examples and comparative examples, the catheter used was a single lumen, with an inner diameter of 1.7 mm at the tip and an outer diameter of 2.35 mm.

Table 1 shows the glass transition temperature of the soft tip, about 20 ° C. corresponding to ordinary room temperature, and about 37 ° C.
The elastic modulus at ° C. is indicated.

[0023]

[Table 1]

The polymers of Examples 1 to 3 and Comparative Example 1 are as follows. Example 1: Ether-based polyurethane [trade name; Diary MM3301 (manufactured by Mitsubishi Heavy Industries, Ltd.), weight average molecular weight;
8 × 10 ⁵ , crystallinity 5.6% by weight] Example 2: Ester-based polyurethane [trade name: Diary MM3611 (manufactured by Mitsubishi Heavy Industries, Ltd.), weight average molecular weight: 3.
2 × 10 ⁵ , crystallinity 45.0% by weight] Example 3: Ether-based polyurethane [trade name: Diary MM4221 (manufactured by Mitsubishi Heavy Industries, Ltd.), weight average molecular weight: 4.
2 × 10 ⁵ , crystallinity: 48.0% by weight] Comparative Example 1: Adipate polyurethane [trade name: E78]
5PNAT (manufactured by Nippon Milactran)]

[0025]

As described above, the catheter of the present invention has a soft tip mainly composed of a polymer whose glass transition temperature is at or near body temperature, and is provided at the distal end thereof. The disadvantages of catheters are eliminated.

That is, before insertion, appropriate rigidity is maintained, and the insertability in the body is good, and after insertion, flexibility is increased by heating by body temperature, so that there is almost no damage to blood vessel walls and cell tissues.

[Brief description of the drawings]

FIG. 1 is a partially omitted plan view showing an embodiment of the catheter of the present invention.

FIG. 2 is a partially omitted plan view showing a conventional catheter.

[Explanation of symbols]

 1: catheter tip 2: soft tip

Claims (2)

(57) [Scope of request for utility model registration] 1. A catheter characterized in that a soft tip mainly composed of a polymer having a glass transition temperature at or near body temperature is provided at a distal end portion thereof. 2. The catheter according to claim 1, wherein the soft tip is covered on a surface of a distal end portion.