JPH0349767A - Catheter using shape memory resin - Google Patents

Abstract

PURPOSE:To make a catheter comparatively hard during operation to insert it to a body cavity and make it soft after it arrives at a prescribed position by forming the catheter with specified shape memory resin and communicating the outgoing path and incoming path of a fluid path, which circulates fluid along a lengthwise axial direction, in the tip part of the catheter. CONSTITUTION:The catheter is made of the shape memory resin, for which an average glass transition temperature is 20-37 deg.C, and the fluid path is formed along the lengthwise axial direction. Then an outgoing path 2 and an incoming path 3 of the fluid path are communicated in a communicating path 4 formed in the tip part. The fluid to be circulated to the fluid path is maintained at a temperature enough lower than a glass transition point and as the fluid, water or air is generally used. Thus, the catheter can be made hard at the time of inserting operation and made soft after it is held. Accordingly, the inserting operation is made easy and further, since a foreign feeling is reduced while the catherter is held in the body cavity, the physical pain of a patient is widely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a catheter formed using shape memory resin.

Note that the term "shape memory resin" as used herein refers to a resin composition in which the ratio of change in elastic modulus before and after the glass transition point is 2 or more.

<Prior art> There are various types of catheters, including those inserted into body cavities for treatment of affected areas and those used for diagnosis such as blood pressure and blood gas analysis. It is preferable to be relatively hard during the process, and to have enough flexibility to prevent deformation and occlusion after reaching the desired position.

Conventionally, catheters made of vinyl chloride have been used, which are hard before insertion and become flexible with body temperature after insertion, but once inserted into a body cavity, they become flexible within a short period of time, making it easy to reach the desired position. The insertion operation was difficult and required considerable skill.

<Problems to be Solved by the Invention> The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a catheter that is relatively hard during insertion into a body cavity and becomes soft after reaching a predetermined position. With the goal.

Means for Solving the Problems> As a result of intensive studies to solve the above problems, the present inventor focused on shape memory resins that have a wide change in hardness (and can freely select the glass transition temperature). As a result, the present invention was completed.

That is, in order to solve the above-mentioned problems, the present invention is formed using a shape memory resin having an average glass transition temperature between 20°C and 37°C, and a fluid that refluxes a fluid along its longitudinal axis. A catheter is used in which the outgoing and incoming passages are connected at the distal end.

<Operation> According to the above configuration, when inserting a catheter fixed into a desired shape into a body cavity, if the catheter insertion operation is performed while circulating cold water, at least the portion of the catheter in contact with the cold water and its adjacent portion will be removed. The temperature of the part is kept below the glass transition temperature. Therefore, the insertion operation can be performed while the rigidity of the catheter is maintained. After the catheter reaches a predetermined position, if the flow of cold water is stopped, the temperature of the entire catheter will rise above the glass transition point and the catheter will become flexible.

<Example> Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 is an explanatory diagram of a catheter according to an embodiment of the present invention. In the figure, (1) is the lumen, (2) is the fluid outward path, (
3) is a fluid return path, and (4) is a communication path.

The catheter of the present invention is made of a shape memory resin having an average glass transition temperature between 20° C. and 37° C., and has a fluid passageway formed along the longitudinal axis of the catheter.

The outward path (2) and return path (3) of the fluid passage are communicated through a communication path (4) formed at the distal end portion of the catheter.

The fluid returned to the fluid passageway is maintained at a temperature well below the glass transition temperature, generally below 10°C. Water or air is generally used as the fluid.

The catheter may be equipped with a pump for suctioning fluid or a pump for pumping fluid (both, if necessary), and a temperature control device for maintaining the temperature of the fluid at a predetermined temperature.

[Example 1] Using a polyurethane shape memory resin (manufactured by Mitsubishi Heavy Industries, Ltd., MM-3500) with an average glass transition temperature of 35°C, a catheter with an outer diameter of 2cm and a length of 50cm as shown in Fig. 1 was made. After making the catheter tip and making it flexible by heating,
While the tip was deformed into a desired shape, cold water maintained at 10° C. or lower was circulated through the fluid passage to cool it and fix the shape. Then, while circulating cold water, the catheter was inserted directly (without using a guide wire) through the femoral artery, and the catheter was left in place with the tip slightly inside the hepatic artery. During this period, the cold water was circulated at a rate of 40 cc/min with a pressure of 3 kg, and the catheter was able to maintain sufficient rigidity to move back and forth or rotate during the insertion operation.

After catheter placement, the circulation of cold water was discontinued, and the catheter became flexible and remained flexible throughout the catheterization period (1 week).

<Effects of the Invention> The catheter of the present invention is made using shape memory resin and has a fluid passage for cooling, so it can be hard during the insertion operation and soft after indwelling.
It is easy to insert the catheter, and there is little discomfort while it is indwelling in the body cavity. FIG. ) is a fluid outward path, (3) is a fluid return path, and (4) is a communication path.

Claims (1)

[Scope of Claims] 1) Outbound and return routes of a fluid passage that is formed using a shape memory resin having an average glass transition temperature between 20°C and 37°C, and that circulates fluid along its longitudinal axis. A catheter in which the two are connected at the tip. 2) The catheter according to claim 1, wherein the fluid is physiological saline maintained at a temperature sufficiently lower than the glass transition point of the shape memory resin. 3) The catheter according to claim 1, wherein the fluid is air maintained at a temperature sufficiently lower than the glass transition point of the shape memory resin. 4) The catheter according to claim 1, further comprising a pump device for sucking and/or pumping the fluid, and a temperature control device for controlling the temperature of the fluid.