JPS5821651B2 - catheter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a catheter and the resulting catheter, particularly a Folley catheter.
ey)・Relating to catheters.

Currently, silicone Foray catheters are formed by joining multiple components by continuous thermocompression molding or by the use of adhesives, have transverse arms and prongs attached, and have an inflatable section and an air inflatable section. is generally formed to have a main hollow tube containing a tube for transmitting.

The continuous heat curing and use of adhesives in molds requires painstaking manual labor and skilled expertise by those familiar with the art of bonding silicone rubber.

Unfortunately, the use of adhesives is time consuming and increases the risk of delamination of the bonding material due to imperfections or leakage at the joint during use.

Heat treatment also takes a long time.

The sections used to make catheters are formed from cross-linked polymeric compositions that have a relatively constant stiffness and modulus of elasticity along their length.

However, it is preferable to provide a catheter with variable stiffness along its length, depending on its location within the human body during use.

For example, the end of an intraoral catheter is preferably softer at the end that is inserted into the larynx than at the opposite end used to handle the catheter.

Employing current methods for making catheters, this preferred feature requires bonding components of different hardness or modulus of elasticity with adhesives, with the disadvantages noted above.

Instead, laborious thermoforming with varying temperatures is considered.

It would be desirable to provide a means for making the catheter and bonding the components by hand or in successive thermoforming steps without the need for it.

By eliminating the manual process, the time required to form the catheter is reduced and problems inherent in the use of adhesives, such as incomplete bonding, incomplete sealing, etc., are also eliminated.

It would be highly desirable to provide a method for forming a catheter formed from sections having non-uniform stiffness or modulus of elasticity along its length.

As disclosed in U.S. Patent No. 3,566,874
This silicone material is prepared by adhering a hydrophilic monomer consisting of hydroxy lower alkyl acrylate or methacrylate to a catheter and exposing the monomer and silicone to gamma radiation to cause polymerization and grafting.
The surface of the catheter can be made hydrophilic.

However, these monomers are not soluble in silicone and the resulting catheter has only a very thin hydrophilic polymer film.

Relatively long times are required to form a hydrophilic surface from these monomers that is thick enough to absorb large amounts of water-soluble fungicides.

Furthermore, the absorbed water-soluble disinfectant is confined to the surface of the catheter and is transferred from the surface to the body within a short period of time during use.

It is highly preferred to provide a silicone catheter that is hydrophilic over a significant portion of its thickness, thereby providing a very large capacity for water-soluble disinfectants.

This provides a means of prolonging the sterilizing action of the catheter during use.

Furthermore, it is also highly desirable to form this type of catheter within a short period of time.

The present invention is based on the discovery that a catheter can be formed by joining silicone sections without the use of adhesives and can be formed with varying stiffness along its length if desired. .

The catheter section is formed from a non-significantly crosslinked moldable silicone rubber stock by conventional methods such as extrusion.

In particular, crosslinking of the polymer chains can be achieved without the entire material having its gel point.

Thus, "not significantly cross-linked" refers to a material that has not reached the gel point but is capable of having a highly branched molecular structure.

The molded silicone is then exposed to a relatively large amount of ionizing radiation;1. Other than the edges of the part that will be joined to other parts,
Cross-link along the exposed length.

These ends are comprised of relatively soft, uncrosslinked silicone that coalesces to the adjacent silicone under slight pressure to form a seamless joint.

If a substantial amount of sol portion remains, this adjacent portion of silicone may cross-link to the extent that it crosses the gel point.

After the non-crosslinked silicones have sufficiently coalesced together to form a seamless bond, they are exposed to ionizing radiation.

The radiation dose depends on the desired final hardness.

Similarly, the stiffness or modulus of elasticity of a section can be easily controlled by varying the longitudinal radiation dose as a function of its length.

In another aspect of the invention, the surface or surface layer of the catheter formed as described above contains a liquid monomer which upon polymerization forms a hydrophilic polymer grafted onto or into the silicone. The monomer is rendered hydrophilic by contacting the catheter and exposing the monomer and catheter to ionizing radiation.

In a preferred aspect of the invention, a silicone catheter formed as described above or otherwise is contacted with N-hinyl pyrrolidone (NVP) monomer, and NVP is applied to a substantial portion of the thickness of the catheter. and exposing the NVP and silicon to ionizing radiation.

Even though the method of the present invention includes a two-step cross-linking process, the formed catheter has the desired strength properties at the joints of its components.

Catheters manufactured using conventional methods have poor strength properties and easily tear at the seam formed between the initially cross-linked silicone and the inserted silicone.

The favorable results obtained with the present invention are believed to be due to the fact that there is no sharp interface between cross-linked and non-cross-linked silicone after the first cross-result step.

Rather, it is assumed that the degree of crosslinking is zero so that there is always at least some silicone that can coalesce with uncrosslinked silicone of adjacent parts and that after coalescing crosslinks to form a seamless joint. There is even a tendency to show

Since the radiation used in the present invention is substantially heat-free,
No special thermal cycling is involved.

Another advantage of using radiation for cross-linking is that any possible toxic catalyst materials are completely avoided, there is no need for the usual peroxidant catalysts used in thermal curing, and 2
There is also no need for metal taps used in component RTV methods.

Compared to the RTV method (room temperature cure), the fully formed joint created can be tested immediately after irradiation, whereas other methods using RTV adhesives or adhesives test the integrity of the seam. You will have to wait a considerable amount of time until it is safe.

A particularly important advantage of the present invention is the ability to design catheters with highly variable longitudinal compliance along the circumference of the catheter, depending on the crosslinking density as indicated by the radiation dose received by the catheter. The catheter can thus be made softer in some places and stiffer in others, and can be easily bulged in other places, depending on the wide range of physiological situations in which it will be used. This is a point that can hardly be extended anywhere else.

The invention will now be described with reference to the accompanying drawings.

In the figure, the catheter (
The catheter consists of several components and includes a main tube 2 and a bifurcated tube 3 with an inlet 4 connected thereto.

The main tube 2 has an outlet section 5 connected thereto.

The main tube 2 has an air passageway 6 extending the length of the main tube and formed in the inner wall of the main tube, as shown in FIG.

The catheter 1 is equipped with an inflatable membrane 7 that seals around the air outlet 8 .

For convenience, this membrane 7 is shown separate from tube 2 in FIG.

It can be seen that during use, the membrane 7 adheres to the tube 2.

Membrane 7 is inflated by air fed through inlet 4 and forked tube 3, air port 10 and air passage 6.

Opposed inlet portions 12 are provided in the inlet portion of the catheter for withdrawing fluid from the human body through passageway 13 and outlet 5.

Catheter 1 is formed by subjecting each component to ionizing radiation that varies along its length.

The ionizing radiation dose can be easily varied by selectively shielding and exposing components to the ionizing radiation source.

For example, with respect to the main tube 2, the portion 2a can be protected from the source of ionizing radiation and is therefore only irradiated to a negligible amount, so that little or no cross-coupling occurs.

Conversely, part 2b is 20 Megarads.
Because it receives relatively large amounts of ionizing radiation up to
Portion 2b is therefore cross-linked and becomes physically stable.

On the other hand, section 2c receives an intermediate amount of ionizing radiation of about 0.5 to 3 megarads, which makes section 2c relatively soft and pliable, but physically strong, so that the inflatable membrane 8 remains within the main tube 2. Adhere to silicone and cross-link.

Similarly, part 3a of side tube 3 and part 5a of outlet 5
are protected from the source of ionizing radiation so that each of them receives no or a relatively low amount of radiation, while portion 3b receives a higher amount of ionizing radiation so that it is cross-linked and made relatively hard.

Like part 3a, part 3c is protected from sources of ionizing radiation, so that if it is desired to join component parts 2, 3, 4.5, 2a can be used to form a seamless joint.
and 5a and portions 3a and 2a are joined together and subsequently cross-linked by exposure to ionizing radiation to form a unitary structure.

Similarly, portion 3c is inserted into the aperture of component 4 to contact the uncross-linked silicone and interlock with the silicone, followed by exposure to ionizing radiation to form a seamless structure. Form a junction.

Suitable silicone polymeric materials that may be used include, for example, difunctional silicone polymers such as dimethyl siloxane, diethyl siloxane, vinyl methyl siloxane, vinylphenyl siloxane, methylphenyl siloxane, and diphenyl siloxane. Homopolymers and interpolymers formed from substituted siloxanes
: Contains, for example, poly[dimethyl-copynylmethyl-siloxane] poly[dimethyl-copynylmethyl-siloxane].

For best results, use molecular weight 10 with up to 60 weight percent fumed silica as reinforcing agent.
0. It is preferable to have a polymer of OQ O or more.

The silicone may also contain other additives consisting of pigments such as titanium dioxide.

Fumed silica is also useful and is added to improve the flow properties of the green polymer by imparting a yield stress so that after molding, uncrosslinked material is easily separated from the mold surface and completely cross-linked. Sag or creep is effectively restrained until bonded.

In another aspect of the invention, the surface of the catheter formed as described above is rendered hydrophilic.

The hydrophilic surface is formed by dipping the catheter into a liquid monomer.

That is, the monomer can be grafted onto the surface of the silicone to form a hydrophilic surface or additional hydrophilic layer of sufficient thickness to absorb water and water-soluble materials.

The soaked catheter and monomer are then combined for a total of 1 to 1
One or more exposures to ionizing radiation in doses between 0 megarads.

Roughly, the rate of radiation dose is about 100 per second, Of)
It should be on the order of 0 rad.

Upon removal of the liquid, the catheter is coated with a hydrophilic layer as evidenced by its intense toluidine blue coloration.

When the grafted area dries, it becomes shiny and glassy and can be more easily inserted into the body in this state than with the initial, somewhat tacky silicone surface.

Another advantage of the hydrophilic coating is that the catheter can be presoaked in various disinfectant solutions, including, for example, benzalkonium chloride, hexachlorophene, iodine, and many other water-soluble ones.

These fungicides bind strongly to the grafted hydrophilic polymers and provide long-term protection against infection.

Furthermore, if a selectively hydrophilized catheter according to the present invention is previously soaked in a disinfectant and dried, the catheter can be easily rewetted before use on a patient, avoiding the usual discomfort. It can be easily inserted without causing any damage.

This is because the rewetted hydrophilic layer is much smoother than the initial silicone layer.

Suitable and preferred monomers include, for example, hydroxy lower alkyl acrylates such as hydroxy ethyl methacrylate (HEMA), methacrylates, or N-vinyl pyrrolidone or mixtures or aqueous solutions thereof.

Radiation must be applied within a short period of time to cause the grafting, otherwise the monomers will gel themselves as they will adhere haphazardly to the silicone surface due to cross-linking.

Therefore, a radiation source such as Kobal 60 is not useful since the required radiation dose is emitted over several hours.

For example, when using pure N-vinylpyrrolidone, a silica-filled silicone catheter is immersed in the solution, and the solution and catheter are connected to a Vande Groff high-voltage electromotive device.
Satisfactory results are obtained by 30 seconds of exposure to 3.5 megarads of radiation from the generator.

In order to form a catheter that is permeable to water or aqueous solutions, it is particularly preferred to employ NVP or an NVP-containing liquid as the hydrophilic polymer.

This is because the NUP dissolves slightly in the silicone and penetrates the silicone catheter to a depth that depends on the soaking time.

Upon exposure to radiation, NVP grafts onto the silicone through its entire thickness or through most of its thickness.

This provides the significant advantage of allowing relatively large amounts of water-soluble disinfectant to be absorbed into the catheter.

Because the disinfectant is distributed over the considerable thickness of the silicone, it can be implanted into the human body over a relatively long period of time.

Additionally, NVP or PVP binds most water-soluble fungicides, such as iodine, more tightly than polymerized acrylates or methacrylates.

The thinner layer is NVP, HEMA (Hydroxy Ethyl
By exposing the silicone to a solution of (methacrylate) and water (thus produced a copolymer of NVP and HEMA with some penetration of NVP into the silicone, mainly in the surface layer, and therefore hydrophilic with NVP) It is possible to absorb a large amount of disinfectant into the silicone.

It will be appreciated that the present invention is useful in all types of catheters, such as ureteral or urethral catheters.

Furthermore, it is understood that the applications described above are incorporated herein by reference.

The following examples illustrate the invention without limiting it.

Example 1 Travenol Foley Catheter (travenol)
A Foley Catheter was immersed in pure NVP monomer, excluding the expansion bulb and drainage tip at one end and beyond the Y-fork at the other end.

Then protect the parts that were not immersed against radiation,
Meanwhile, the area exposed to NVP was irradiated with 1.5 megarads of radiation twice for 30 seconds each.

After irradiation, excess NVP was removed by washing.

After 4 hours of immersion in an aqueous toluidine blue solution, the blue coloration penetrated to a depth of 0.3 mvt, indicating the presence of the hydrophilic grafted PVP silicone copolymer.

Example 2 The same catheter as in Example 1 was prepared with an NV of 4×X% by weight.
It was similarly partially immersed in an aqueous solution of P, 16% HEMA, 80% water and irradiated once with a total of 3.5 megarads.

After this treatment and rinsing, the catheter was found to have a thin, superficial layer that strongly absorbed Troidin Blue from aqueous solutions.

The thickness of this coating when expanded was approximately 50 microns.

The embodiments of the present invention will be described as follows.

(1) forming a plurality of catheter components from a silicone composition that is not sufficiently cross-linked and thus has not reached its gel point, and ionizing each of the components to cross-link the silicone composition; the radiation dose to which each component is exposed is such that the degree of cross-linking of at least a portion of each component that is bonded to an adjacent component in forming the catheter is sufficiently low that the silicone of that portion is and non-cross-bonded portions that are controlled to interbond with the silicone of adjacent components and interbonded to cross-bond the sections and form a seamless joint between the components. A method of forming a catheter, the method comprising exposing the catheter to ionizing radiation.

(2) In addition to the portions that are joined to adjacent component parts, at least one of the component parts is connected in its second part to a part that extends in the longitudinal direction of the second part in order to change the hardness of the second part. The method according to (1) above, characterized in that the method comprises exposing the method to ionizing radiation that varies depending on the temperature.

(3) contacting the catheter thus formed with a liquid monomer that is polymerized to form a hydrophilic polymer and grafting the hydrophilic polymer onto or into the surface layer of the catheter; The method of (1) above, in which the catheter and monomer are exposed to a large amount of ionizing radiation for a short period of time.

(4) contacting the catheter thus formed with a liquid monomer that is polymerized to form a hydrophilic polymer and grafting the hydrophilic polymer onto or into the surface layer of the catheter; The method of (2) above, in which the catheter and monomer are exposed to a large amount of ionizing radiation for a short period of time.

(5) The method of (3) above, wherein the monomer comprises N-vinyl pyrrolidone.

(6) The method of (4) above, wherein the monomer is N-vinyl pyrrolidone.

(7) The method of (3) above, wherein the monomer comprises a mixture of N-vinyl pyrrolidone and alkyl methacrylate in an aqueous solution.

(8) The above (wherein the monomer is a mixture of N-vinyl pyrrolidone and alkyl methacrylate in an aqueous solution)
Method 4).

(9) Contacting a liquid monomer composition containing the N-vinyl pyrrolidone to penetrate the catheter into a substantial thickness of the catheter, and then exposing the catheter to the monomer in large amounts for a short period of time. A method of rendering a catheter constructed from a silicone composition hydrophilic, comprising exposing the monomer to ionizing radiation of ionizing radiation to polymerize the monomer and graft the N-vinyl pyrrolidone to the silicone.

(10) The method of (9) above, wherein the liquid monomer composition comprises an aqueous solution of N-vinyl pyrrolidone.

(11) The method of (9) above, wherein the liquid monomer composition comprises pure N-vinyl pyrrolidone.

(12) A catheter made from a flexible silicone composition having grafted polyvinylpyrrolidone extending a substantial thickness from the surface of the catheter.

[Brief explanation of drawings]

FIG. 1 is a side view of the components of a ureteral catheter before being joined to form a catheter. FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1... Catheter, 2... Main tube, 6... Air passage, 7... Inflatable membrane.

Claims (1)

[Claims] 1. A liquid monomer composition is brought into contact with a catheter constructed of a silicone composition to penetrate a substantial thickness of the catheter, and the catheter and the liquid monomer composition are exposed to a source of large amounts of ionizing radiation for a short period of time. 1. A method of rendering hydrophilic a catheter constructed from a silicone composition, comprising exposing the monomer composition to polymerization and grafting onto silicone.