JPH08275991A - Medical device - Google Patents

Abstract

PURPOSE: To improve the safety of product by minimizing an electron beam emission distribution by use of a shielding material in a medical device sterilized with electron beam, particularly, a blood filtering device or blood dialyzing device. CONSTITUTION: In the application to an artificial dialyzing device consisting of a hollow yarn, electron beam emission is used at sterilization, and the emission distribution within the artificial dialyzing device is measured by use of a chemical indicator. When it does not reach a necessary emission, beam current, conveyor speed and bus frequency are examined and set to sterilizable conditions. Since the emission is varied when the direction of the electron beam emitted to the artificial dialyzing device is varied, an urethane part, at the emission in parallel to the hollow yarn, and the part of the hollow yarn, at the emission vertical to the hollow yarn, are shielded by a shielding material, respectively. Thus, the electron beam emission distribution shown by the ratio of maximum emission to minimum emission is minimized to improve the safety as product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical device sterilized by electron beam irradiation, and more particularly to a hemofiltration device / hemodialysis device. More specifically, the present invention relates to a medical device that has been sterilized without increasing the distribution of electron beam irradiation.

[0002]

2. Description of the Related Art In recent years, in the medical field, hemodialysis performed by patients with renal diseases who have lost renal function has become synonymous with so-called artificial kidneys. The three mainstream sterilization methods of the artificial kidney dialysis apparatus that have been put into practical use are a gas sterilization method using ethylene oxide gas or the like, an autoclave method using high-pressure steam, and a γ-ray irradiation method. Among them, the ethylene oxide method has a problem that the ethylene oxide gas remains, and requires sufficient degassing so as not to cause toxicity. Further, since the pressurization and the depressurization are repeatedly performed, the processing time is long, and the performance may change depending on the material.

The autoclave method and the γ-ray irradiation method depend on the properties of the materials constituting the dialysis machine. In the former autoclave method, the heat resistance of the hollow fiber in a wet state becomes a problem, and depending on the material, the performance may be significantly reduced, and the autoclave method may not be used. The latter γ-ray irradiation method has an excellent sterilization effect and is an excellent sterilization method without the problem of residual ethylene oxide gas unlike the gas sterilization method.
However, performance, eluents, and
In many cases, problems such as strength and physical properties are shown, and it has been necessary to select and develop materials. In addition, as the irradiation method at the time of γ-ray irradiation, Japanese Patent Publication No. 55-26620 and Japanese Patent Publication No. 3-1
As described in No. 0343, a method has been devised in which a dialysis device is filled with an inert gas, water or the like and sterilized while preventing deterioration.

On the other hand, in recent years, electron beam irradiation has attracted attention as a method of sterilizing medical devices and the like by increasing the acceleration voltage. The characteristics of the sterilization method by electron beam irradiation are that there is no concern about residual toxicity unlike the ethylene oxide gas method, and the autoclave method, ethylene oxide gas method,
Unlike the γ-ray irradiation method, the sterilization time is not long and can be processed in a short time. Further, when the power is turned off, the irradiation is instantaneously stopped, and there is no need to consider the storage of radioactive substances such as a γ-ray irradiation facility, which is environmentally safe and inexpensive in terms of cost. Furthermore, the major difference from γ-rays is that material deterioration is small. Therefore, there is an advantage that the range of material selection is wide.

However, the disadvantage of electron beam irradiation is that it has a small penetrating power unlike γ-ray irradiation, and its penetration distance is said to depend on the surface specific gravity of the material to be irradiated. Therefore, in the current electron beam irradiation method, this problem has been solved by a method of irradiating from both sides twice, a method of devising the irradiation direction for the product shape, or a method of increasing the acceleration voltage. However, most products that have adopted the electron beam irradiation method as a sterilization method so far have a relatively uniform shape such as surgical gloves, surgical sheets, surgical clothes, sutures, etc. It was possible to irradiate. However, medical devices called artificial organs such as artificial dialysis machines and artificial lungs made of hollow fibers are
It has many members and complicated shapes. Therefore, when the electron beam was irradiated, the distribution of the irradiation amount in one product was large due to the difference in the specific gravity of the members. The irradiation distribution here is the ratio of the maximum irradiation amount to the minimum irradiation amount, and the larger the value, the more problems have occurred in safety, product management, performance and the like.

[0006]

Therefore, in the present invention, in the electron beam irradiation sterilization of a medical device having a complicated form such as a dialysis machine, the electron beam irradiation distribution is made as small as possible to improve the safety as a product. Is.

[0007]

The above problems can be solved by the present invention described below.

(1) A medical device sterilized by electron beam irradiation, characterized in that a shield material is used to reduce an electron beam irradiation dose distribution.

A more detailed description will be given below based on the embodiments of the present invention.

As a product having many members and a complicated shape, an artificial dialysis device consisting of hollow fibers will be mainly described.

First, ordinary electron beam irradiation is performed, and the dose distribution in the artificial dialyzer is measured using a chemical indicator. At this time, it is necessary to sterilize the beam current, the conveyor speed, the number of passes, etc., when the required irradiation dose is less than the minimum condition that the minimum irradiation dose is sterilizable. At this time, the irradiation direction may be reversed and irradiation may be performed twice. Further, if the direction of the electron beam applied to the artificial dialysis device is different, the irradiation amount is completely different. For example, when irradiated in parallel to the direction of the hollow fiber (the direction of blood flow), the hollow fiber part shows the minimum irradiation amount and the potting urethane part shows the maximum irradiation amount, but when irradiated perpendicularly to the hollow fiber, On the contrary, the hollow fiber portion shows the maximum irradiation amount, and the potting urethane portion shows the minimum irradiation amount. Therefore, when irradiated in parallel to the direction of the hollow fiber, the urethane part is shielded by the shield material, and when irradiated perpendicularly to the hollow fiber, the hollow fiber part is shielded by the shield material. Either method may be used, but the direction should be set so that it is easy to shield when irradiating. Further, it is possible to make the artificial dialysis device have a uniform irradiation by controlling the shielding amount for the irradiation amount between the maximum irradiation amount and the minimum irradiation amount.

The prepared dialysis device is wrapped with a packaging material such as polyethylene. At this time, the filling of an inert gas, the use of vacuum, or the use of an oxygen scavenger or the like in an oxygen-free state is not particularly limited, but it is an effective means when it is necessary to deal with the deterioration of the material. The prepared artificial dialysis device is packed in a box in units of 10 to 12 and irradiated with an electron beam.

The shield material may be set inside or outside the box packed, but it is installed so as to be perpendicular to the electron beam irradiation direction. In addition, be careful that the installed shield material is located exactly where it will be shielded.

As the material of the shield material, a metal sheet and a polymer sheet containing a metal powder, an inorganic material having a large specific gravity such as a contrast agent, or a compound can be considered. At this time, the kind of metal is not particularly limited.

The contrast agent is not a problem as long as it is a compound used as a general contrast agent such as tungsten, bismuth oxide, and barium sulfate, but a contrast agent having a high compatibility with a polymer or a high contrast property is used. Considered to be effective. The type of polymer is not particularly limited.

Further, substances other than polymers may be used as long as they are compatible with these contrast agents. Further, the amount of the contrast agent added and the thickness of the shield material are adjusted in proportion to the ratio of blocking the electron beam.

For example, electron beam irradiation is performed without using a shield material, a map showing the contour lines of the irradiation amount is prepared, and the thickness of the shield material is adjusted so as to be proportional to the map.

The shield material of the present invention can be reused as long as the material is not deteriorated.

[0019]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 PTMG-Ny. Several chemical indicators are installed in a dialysis machine made of BI hollow fiber membrane as shown in FIG. On the other hand, the shield material is
Tungsten was added at 50 wt% to soft vinyl chloride containing 52 parts by weight of a plasticizer added to 100 parts by weight of vinyl chloride, kneaded, and then rolled and pressed to obtain a uniform sheet having a thickness of 2 mm. This is cut out so as to fit the portion with excessive irradiation amount (see Comparative Example 1). Next, the three sheets were placed on the outside of the dialysis machine where there was excessive irradiation (Comparative Example 1).
Fix it at the position of reference, B, C, D, E) and wrap it in polyethylene packaging. This was packaged in units of 12 tubes and irradiated with an electron beam so as to be perpendicular to the hollow fiber direction. Irradiation conditions are acceleration voltage: 5 MeV, beam current: 10 m
A, the conveyor speed was 5.6 m / min, and it was turned upside down in the direction of the dialysis port and irradiated twice. Table 1 shows the irradiation dose at each site obtained from the indicator shown in FIG. 1 at this time. The ratio of the maximum dose to the minimum dose (irradiation distribution) is 1.4
It was 0.

PTMG: polytetramethylene oxide Ny. BI: Polyamide composed of 1,3-bisaminomethylcyclohexane (B) and isophthalic acid (I)

(Example 2) PTMG-Ny. In the dialysis machine consisting of BI hollow fiber membrane
1 x 1 of us Pumilus (ATCC27142)
0 ⁶ pieces were applied and irradiated with an electron beam under the same conditions as in Example 1.
No bacterium was detected after electron beam irradiation, confirming the sterilization effect.

(Comparative Example 1) In Example 1, all conditions were the same except that the shield material was not used. The irradiation amount obtained from the indicator at the same position as in Example 1 at this time is shown in Table 2. The ratio of the maximum irradiation amount to the minimum irradiation amount (irradiation distribution) was 3.05.

(Example 3) Several chemical indicators were placed at the positions shown in FIG. 2 in the same manner as in Example 1 in an artificial lung consisting of a polypropylene porous hollow fiber membrane. On the other hand, as the shield material, the same soft vinyl chloride sheet containing tungsten as in Example 1 was used. This is cut out so as to fit the portion with excessive irradiation amount (see Comparative Example 2). Next, polyethylene packaging and boxing are performed, and 11 sheets are fixed to the outside of the box so as to correspond to the over-irradiated portion of the artificial lung (see Comparative Example 2, at positions corresponding to G, I, N and P). 3 sheets, J,
4 pieces at the position corresponding to L). This was irradiated with an electron beam so as to be perpendicular to the fiber direction. The irradiation conditions were: accelerating voltage: 5 MeV, beam current: 10 mA, conveyor speed: 3.5 m / min, upside down in the direction of the blood port, and irradiation was performed twice. Table 3 shows the irradiation dose at each site obtained from the indicator shown in FIG. 2 at this time. The ratio of the maximum irradiation amount to the minimum irradiation amount (irradiation distribution) was 1.43.

(Comparative Example 2) In Example 3, all conditions were the same except that no shield material was used. The irradiation dose obtained from the indicator at the same position as in Example 3 at this time is shown in Table 4. The ratio of the maximum irradiation amount to the minimum irradiation amount (irradiation distribution) was 4.50.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

INDUSTRIAL APPLICABILITY The medical device of the present invention can be improved in safety by reducing the irradiation distribution by electron beam irradiation sterilization using a shield material.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a dialysis device according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of an artificial lung according to an embodiment of the present invention.

[Explanation of symbols]

 10 Dialysis machine 11 Blood port 12 Potting urethane part 13 Dialysis port 14 Hollow fiber 15 Artificial lung 16 Blood port 17 Gas exchanger part 18 Heat exchanger part 19 Hollow fiber 20 Water port 21 Gas port 22 Stainless pipe

Claims (1)

[Claims] 1. A medical device sterilized by electron beam irradiation,
A medical device characterized in that the electron beam irradiation distribution is reduced by using a shield material.