CA1064337A

CA1064337A - Method of making a catheter with x-ray opaque markings

Info

Publication number: CA1064337A
Application number: CA241,549A
Authority: CA
Inventors: Joseph H. Corbett
Original assignee: Sherwood Medical Industries Inc
Current assignee: Sherwood Medical Co
Priority date: 1974-12-20
Filing date: 1975-12-11
Publication date: 1979-10-16
Also published as: BE836878A; FR2294718B1; AU8675875A; FR2294718A1; GB1511269A; JPS5187388A; DE2553100A1

Abstract

ABSTRACT OF THE DISCLOSURE
Disclosed is a method of making an elongated medical catheter having an x-ray opaque marking comprising the steps of: extruding an elongated plastic tubular member, then coating a selected surface area of the tubular member with a mixture while leaving other areas free of the mixture, the mixture including an x-ray opaque material and a solution, the solution comprising a plastic material and a solvent therefor, and solidifying the coating in situ to provide an x-ray opaque marking on the tubular member.
The marking is formed in its entirety from the mixture and the solution is in liquid form when at room temperature prior to the step of solidifying the coating, and the solvent is also a solvent for the plastic material of the tubular member.

Description

-` ~064337 METHOD OF MAKING A CATHETER WITH X-RAY OPAQUE MARKINGS
. . . _ BACKGROUND OF THE INVENTION
As iS well-known, it is often necessary to determine the depth of penetration or the position of a particular portion of a catheter, such as the distal tip or fluid inlet or outlet openings, after the catheter has been inserted into the body of a patient. For this reason, plastic catheters have been provided with at least portions thereof formed of x-ray opaque materials. For examplej x-ray opaque material can be mixed with the plastic and the mix-ture extruded to form a catheter which is entirely x-ray opaque, although the cost of the materials is relatively high. Where it is not necessary or desired to make the entire catheter opaque, x-ray opaque material can be added to the plastic at selected intervals during its extrusion.
Also, plastic with x-ray opaque material can be extruded onto the catheter or in its wall to form a stripe which, if desired, may be interrupted in selected areas. With these methods, the location and/or configuration of the desired x-ray opaque markings are limited by the capabilities of the extrusion process. In U.S. Patent No. 3,605,750, a separate part, which may also be an extrusion, is formed of ; plastic and x-ray opaque material and fused or attached by heat and pressure to a plastic catheter. This latter method is relatively expensive since it involves the making and handling of separate parts, and the fuslng of them to selected areas on the catheter.

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`` ~o643;~7 SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved method of making a plastic catheter having a selected area which is x-ray opaque wherein the catheter is relatively economical and the form or shape of the x-ray opaque area is not limited by extrusion process restrictions.
The invention in its broader claimed aspect comprehends a method of making an elongated medical catheter having an x-ray opaque marking comprising the steps of:
extruding an elongated plastic tubular member, then coating a selected surface area of the tubular member with a mixture while leaving other areas free of the mixture, the mixture including an x-ray opaque material and a solution, the solution comprising a plastic material and a solvent therefor,and solid-ifying the coating in situ to provide an x-ray opaque marking on the tubular member. The marking is formed in its entirety from the mixture and the solution is in liquid form when at room temperature prior to the step of solidifying the coating, and the solvent is also a solvent for the plastic material of the tubular member.
These as well as other objects and advantages of the present invention will be apparent from the following detailed description and accompanying drawing wherein like reference characters refer to like parts.
` BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is an elevational view of a catheter made i` - in accordance with the present invention;
Figure 2 is an elevational view of a modified form of catheter made in accordance with the invention;

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Figure 3 is an elevational view of a part of a modified form of catheter or rod made in accordance with the invention; and Figure 4 is an elevational view of a part of a still different form of catheter or rod made in accordance with the invention.
DESCRIPTION OF THE PREEERRED EMBODIMENT
Referring now to the drawing, a thoracic catheter 10 is shown for illustration in Eigure 1 in the form of an open-ended elongate plastic tube having a lumen 12 and a plurality of holes or eyes 14 in the side wall of the tube which communicate with the lumen 12 near the upper or ~ distal end 15 of the tube. The catheter has an enlarged, - generally conical, lower or proximal end 16 which serves as an adaptor for connection with another device such as a drainage tube. The lower end 16 is beveled at 18 to facilitate placement of the catheter following chest surgery.
In the case of a thoracic catheter, such as catheter 10, it is desirable or necessary to position or determine the position of the most proximal eye relative to the chest wall by means of x-ray observation. For this reason, the catheter 10 is provided with a layer or film of an x-ray opaque material indicated at 20. The layer 20 is in the form of a closed or annular ring extending around the periphery of the proximal eye, that is, the eye 14 which is farthest from its distal end 15.
The layer 20 thus serves as an x-ray opaque marking which can be seen by x-ray observation, such as by x-ray film, fluoroscope, or the like, so that the catheter 10 may be positioned to precisely locate the most proximal eye 14 in a desired location after insertion of the catheter into a patient.
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The catheter 10 may be made by extruding a suitable plastic material, cutting or punching the desired openings therein, coating a selected surface area of the catheter with a mixture which includes a liquid plastic material and an x-ray opaque material, and then solidifying the applied coating in situ to provide the x-ray opa~ue layer or marking 20. The coating can be applied by means of a brush, offset printer, nozzle, or by any other suitable means for applying the liquid coating to the catheter. Depending upon the particular type of plastic, the applied coating may be solidified in situ by drying, jelling, or curing.
Catheter 10 is preferably formed of polyvinyl chloride, and the marking 20 is preferably formed of a solidified mixture of polyvinyl chloride and an x-ray opaque material such a$ tungsten powder. Since the plastic materials ; of the tube and the x-ray opaque marking 20 are of the same kind, excellent adhesion of the marking layer to the tube is obtained.
The marking 20 may be applied by preparing a mixture of conventional polyvinyl chloride compound, such as in pellet form, and tungsten powder in a suitable solvent, such as cyclohexanone. For example, equal amounts of ;~ polyvinyl chloride pellets and tungsten powder, by weight, can be mixed with an amount of solvent for the plastic that will provide a mixture of desired consistency or viscosity ^ to allow the mixture to be easily applied to the .,~ .
selected areas or surfaces of the plastic tube, for example, by brushing or offset printing. The mixture may be one of very low viscosity, such as a thick paste, or it may be a thin or highly viscous mixture. After the desired surface . ' .

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,, 10~;4;~37 , of the catheter has been provided with a coating of the mixture mentioned above, the coating is solidified by air-drying to drive off the solvent and produce a dry layer of x-ray opaque material tenaciously adhering to the tube.
Alternatively, a plastisol of polyvinyl chloride mixed with tungsten powder may be applied to the polyvinyl chloride tubing by brushing it on or by any of the other methods mentioned above. In this case, the liquid coating of tungsten and plastisol is jelled or heat cured in situ to solidify it by heating the liquid coating to its jell temperature, which temperature will depend upon the particular plastisol used. Such plastisols are, of course, well-known and commercially available. Some plastisols, for example, jell between about 150 and 180F. A typical plastisol includes polyvinyl chloride and di-octl-phthalate (DOP~.
In Figure 2 there is shown a catheter 22 which is of the umbilical artery type and which is also preferably ~ -formed of polyvinyl chloride. In this case, the catheter is provided with an enlarged conical end 24 adapted to receive the end of a tube or other device. The catheter 22 is provided with three dots 26 of x-ray opaque material which may serve as marks forgauging the depth of insertion of the distal end portion of the catheter into a patient.
- These dots can be of the same material as that of the layer 20 of Figure 1, and can be applied in the same manner -as layer 20. The upper distal tip of catheter 22 is provided with a coating 28 which may be of the same x-ray opaque material as the dots. The upper end portion of catheter 22 may be, for example, dipped in the mixture containing liquid polyvinyl chloride solution and tungsten ~-., .

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-powder so that the inner and outer walls at the upper end of the catheter and the tip end of the catheter are coated.
Figure 3 shows a fragmentary portion of a rod or catheter 30 for insertion into the body which has a closed ring 32 of x-ray opaque material adhered to its outer surface. In Figure 4, a stripe 34 extends lengthwise on a plastic tube 36 to provide an x-ray opaque stripe which may either be continuous from one end to the other or interrupted to provide a series of lines. The tubes 30 and 36 in Figures

3 and 4 can be formed of polyvinyl chloride so that a mixture of liquid polyvinyl chloride solution and tungsten powder may be applied and solidified to form the marks 32 and 34.
When the markings 20 in Figure 1, 26 and 28 in Figure 2, 32 in Figure 3, and 34 in Figure 4 are provided by , applying the mixture containing the x-ray opaque material -~
and solution of plastic and solvent therefor, the coating can, of course, be air-dried, such as by heated air, to solidify 'he coating. When the above-mentioned mixture containing liquid plastisol is uYed, the coating forming these markings is solidified by raising it to the jelling or curing temperature, as previously mentioned.
When polyurethane tubing is to be provided with x-ray opaque markings, a conventional dipping solution of polyurethane compound may be provided with x-ray opaque material, such as tungsten powder, and applied in any suitable manner to the polyurethane tubing. After the mixture is applied, it is then air-dried or dried in a heated ` atmosphere to provide a solidified polyurethane and tungsten layer which tenaciously adheres to the polyurethane tubing and serves as an x-ray opaque marking.

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If the plastic tubing is made of silicone rubber, a mixture of conventional silicone rubber compound and x-ray opaque material, such as tungsten, in a suitable solvent for the rubber such as Toluene or Xylene, may be applied to the tubing. The applied coating is solidified such as by drying, for example, in an oven to remove the solvent, and is then heat cured. In this manner, suitable x-ray opaque markings which adhere to the silicone rubber catheter are provided.
Other well-known x-ray opaque materials such as barium sulfate or tin, as well as others, may be used instead of tungsten powder. Also, the polyvinyl chloride compound may contain softeners and stabilizers.
By applying a mixture which includes a plastic :,. .. ,. - , ' ~` solution and x-ray opaque material to the catheter or rod, f a great variety of markings can be readily obtained in a simple and economical manner.
Various other well-known additives, such as fillers, ,~ colors, etc., may be added where desired to the liquid ;~
containing the plastic and x-ray opaque material.
While a preferred form of the invention has been ~' described herein, it will be apparent that various changes and modifications thereto may be made without departing from ., .
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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of making an elongated medical catheter having an x-ray opaque marking comprising the steps of:extruding an elongated plastic tubular member, then coating a selected surface area of said tubular member with a mixture while leaving other areas free of said mixture, said mixture including an x-ray opaque material and a solution, the solution comprising a plastic material and a sol-vent therefor, and solidifying said coating in situ to provide an x-ray opaque marking on said tubular member, said marking being formed in its entirety from said mixture, said solution being in liquid form when at room temperature prior to said step of solidifying said coating, and the solvent also being a solvent for the plastic material of the tubular member.

2. The method of Claim 1 wherein said tubular member is formed of the same type of plastic material as the plastic material of said mixture.

3. The method of Claim 2 wherein said plastic material is polyvinyl chloride.

4. The method of Claim 2 wherein said solvent is cyclohexanone.

5. The method of Claim 2 wherein said plastic material comprises polyurethane.

6. The method of Claim 2 wherein said plastic material is silicone rubber.

7. The method of Claim 1 wherein the plastic material of said mixture comprises polyvinyl chloride plastisol.

8. The method of Claim 7 wherein the step of solidifying said coating includes heating the same to the jell temperature of the plastisol.

9. The method of Claim 1 wherein said tubular member is formed of polyvinyl chloride compound and said plastic material of said solution includes polyvinyl chloride compound.

10. A method of making a medical catheter having an x-ray opaque marking thereon comprising the steps of: extruding an elongated plastic tube,mixing materials including an x-ray opaque material and a solution of a plastic material and a solvent therefor to provide a mixture wherein the solution is in liquid form when at room temperature prior to solidification thereof, applying the mixture to a selected surface area of the tube while leaving other areas free of the mixture, and solidifying the applied mixture in situ to provide an x-ray opaque marking on the tube formed in its entirety from said applied mixture, the solvent also being a solvent for the plastic material of the tube.

11. The method of Claim 10 wherein said plastic material comprises polyvinyl chloride plastisol.

12. The method of Claim 10 including the step of cutting the tubing to a desired size before said step of applying the mixture to the tube.

13. The method of Claim 10, 11 and 12 wherein said tubular member is formed of the same type of plastic material as the plastic material of said mixture.