Hydrophobic Catheter Construction

Abstract

A catheter construction having a hydrophobic inner surface adapted to provide extended blockage-free use. The inner surface is defined by a coating of hydrophobic silicon dioxide. The coating may be adhered to the catheter tubular wall by heat fusion, adhesive, etc., means. In one heat fusion method, the inside surface of the catheter tubing is heated while maintaining the remainder of the tubing at relatively low temperature to maintain the tubular integrity thereof while bonding the hydrophobic material to the heated wall surface. In another method of producing the catheter, powdered hydrophobic material is packed in the tubing and the packed tubing is suitably treated to effect the desired coating whereupon the remaining particulate material is removed from the tubing as by fluid flow therethrough. In still another method of forming the catheter construction, the tubing and coating may be effectively concurrently formed.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to catheter constructions and in particular to catheter constructions arranged to provide extended blockage-free use.

2. Description of the Prior Art

Catheters have long been utilized for draining body fluids and the like. One such common use is in the draining of urine. It has been found that in such uses the conventional catheter constructions tend to block up after a period of time requiring removal of the catheter and either removal of the blockage or insertion of a replacement catheter. Such operations are painful, time consuming, and possibly injurious to the patient, and it is, therefore, a desideratum that effectively maximum blockage-free operation of the catheter be obtained to minimize the need for such removal and replacement.

A number of different catheter materials have been employed in an effort to find a catheter construction which would provide substantially extended blockage-free use. None of the known catheter constructions, however, have been fully satisfactory in solving this vexatious problem.

SUMMARY OF THE INVENTION

The present invention comprehends an improved catheter construction which provides substantially extended blockage-free use solving this longstanding vexatious problem in a novel and simple manner.

More specifically, the invention comprehends providing on the inner surface of a plastic tubular catheter a hydrophobic coating of silicon dioxide, effectively avoiding a blockage of the catheter passage by deposited material such as urine salts. The catheter tubing may be formed of an elastomeric polymeric material such as a vinyl plastic, latex rubber, etc. The hydrophobic coating may be effectively retained on the catheter tubing by a number of different methods so as to provide a water repellent pellent surface defined by microscopic projections having interstitial air capillaries. The liquid tends to be carried on the projections to maintain a body of air in the interstitial spaces.

One improved method for applying the hydrophobic silicon dioxide comprehends extruding the tubing of synthetic thermoplastic resin or rubber latex and flowing a stream of hydrophobic silicon dioxide material against the inner surface of the extruded tubing so as to effect a heat fusion of the hydrophobic material thereto and as a result of the heat energy of the extruded tubing. The tubing may be concurrently exteriorly cooled and delivery of the flowed hydrophobic material may be suitably spaced from the point of extrusion of the tubing so as to cause impingement of the material on the tubing inner surface at a point where the temperature is a preselected fusion bonding temperature.

Alternatively, the hydrophobic material may be packed in particulate form in previously formed tubing and the packed tubing subjected to heat or heat and pressure, such as steam pressure, to effect the desired fusion bonding to the inner surface. The excess powdered material is then removed such as by blowing the material outwardly from the tubing to complete the manufacture.

Another method of forming the coating comprises dipping the completed catheter tubing material in a liquid carrying the hydrophobic material and allowing the liquid vehicle to evaporate to effect the desired bonded coating deposition.

Alternatively, the coating may be adhered to the tube surface by adhesive bonding methods. Illustratively, an adhesive may be flowed through the tubing to provide a coating on the inside surface thereof and the hydrophobic material subsequently flowed through the adhesively coated tube to provide the coating deposit. The hydrophobic material may be flowed in a body of cool air to effect a setting of the adhesive. Further alternatively, the hydrophobic material may be packed in the adhesive coated tubing and subjected to a setting heat, as in an oven, to effect the desired set bond.

Where the tubing is formed with the coating prior to the manufacture thereof into the catheter construction, the portions of the catheter construction not so coated, such as the tip or outside surface of the tube, may be subsequently treated as by any of the above methods to complete the coating of all desired surfaces with the hydrophobic material .

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIG. 1 is a fragmentary side elevation illustrating one method of applying the hydrophobic coating to a catheter tube;

FIG. 2 is an enlarged transverse section taken substantially along the line 2--2 of FIG. 1;

FIG. 3 is a fragmentary side elevation illustrating the coating of an end portion of the catheter construction;

FIG. 4 is a fragmentary side elevation with portions shown in diametric section illustrating another method of coating the catheter tubing;

FIG. 5 is an isometric view shown with a portion broken away illustrating another method of providing the catheter construction coating;

FIG. 6 is a fragmentary side elevation with portions shown in diametric section illustrating still another method of coating the catheter tubing;

FIG. 7 is an isometric view with a portion broken away illustrating still another method of providing the catheter construction coating;

FIG. 8 is a fragmentary side elevation illustrating still another method of providing the catheter construction coating; and

FIG. 9 is a transverse section of the catheter construction coated tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the exemplary embodiments of the invention as disclosed in the drawing, a catheter construction generally designated 10 is shown to include a flexible tubular catheter element 11 provided with a coating 12 on the inner surface 13 of the tubular catheter element. The coating comprises a coating of hydrophobic material providing improved liquid flow through the passage 14 of the catheter to effectively provide extended blockage-free use of the catheter such as in draining of body fluids.

More specifically, the hydrophobic material may comprise a fumed silicon dioxide material providing a rough outer surface which cooperates with the hydrophobicity provided by the chemical nature of the material to minimize the wetting of the coating surface by liquids such as aqueous solutions and more specifically, body fluids. The fumed silicon dioxide provides microscopic projections which tend to support the water on the tips of the projections so as to provide open spaces between the tips and thereby providing substantially increased hydrophobic characteristics of the coating. The coating preferably exhibits a contact angle with water of between approximately 125.degree. and 150.degree.. While a number of different hydrophobic materials may be utilized providing such hydrophobicity, it has been found that an excellent material for this purpose is that identified as Silanox marketed by Cabot Corporation, of Boston, Massachusetts, and comprising a fumed silicon dioxide reacted with a silane to define the following molecular structure: ##SPC1##

Such Silanox material is marketed under the grade identification of Silanox 101 and has the following physical characteristics:

Appearance -- Superfine, fluffy white powder

Surface area -- 225m.sup.2 /gm (BET)

Primary particle size -- 7 m.mu.

Bulk density -- 3 lbs./cu. ft.

325 mesh residue -- 0.02%

*pH -- 8-10

Specific gravity -- 2.2

X-ray structure -- Amorphous

*4% dispersion of Silanox 101 in 50% IPA/50% water.

The fumed silicon dioxide may be produced by the hydrolysis of silicon tetrachloride in a flame process to produce a silicon dioxide material which is nonporous, amorphous, of high chemical purity, and of large specific surface area. The particles are sintered into long, branched, submicron sized aggregates which are then reacted with the silane material to replace hydroxyl groups with hydrophobic hydrocarbon groups.

It has been unexpectedly found that by providing a low wetting characteristic to the inner surface of a tubular catheter, a substantially blockage-free characteristic of the catheter is obtained, permitting extended retention of the catheter in the body orifice and avoiding the need for periodic removal and replacement of the catheters as has been required in the past with conventional catheter constructions. Thus, it has been found that not only does the provision of the hydrophobic coating 12 on catheter surfaces 13 provide for facilitated flow of the body fluids through the catheter for facilitated removal of the body fluids from the patient, but also provides synergistically a blockage-free operation eliminating the vexations and serious problem of required periodic replacement of the conventional catheters.

The catheter construction of the present invention may be formed in a number of novel manners. More specifically, as shown in FIGS. 1 and 2, a tube 15 of suitable catheter material may be extruded from a conventional extruder 16 through a head 17. Concurrently with the extrusion of the tube 15, Silanox material may be directed against the inner surface 18 of the tube by means of a nozzle 19 projecting coaxially through extrusion head 17 and provided with a plurality of radial passages 20. The material may be urged outwardly from the nozzle 19 by means of a pressurized fluid, such as air, which may be relatively cool so as to cause the setting of the Silanox material on the tube surface 18 in the form of a thin coating 21. Thus, the coating may be bonded to the tube surface 18 by a fusion bonding action as a result of the thermal energy of the extruded tube 15. The outer surface 22 of the tube may concurrently be cooled by directing cooling air thereagainst by means of an air flow structure 23. Thus, the coated tube may be quickly set in the desired final configuration with the coating of hydrophobic material permanently bonded to the inside surface.

In forming the completed catheter construction, a tip portion 24 may be secured to one end of a cut length of the coated tube, as shown in FIG. 3, and the tip provided with a coating of the hydrophobic material as by dipping the tip in a fluidized bed 25 thereof. Alternatively, the tip 24 may be heated by suitable heating means and merely dipped into a body of powdered hydrophobic material to effect the desired bonded coating.

As shown in FIG. 4, the catheter may further include a connecting portion 26 attached to the opposite end of the tube 15. As further shown in FIG. 4, the coating of the inner surface 18 of the tube may be provided by packing the powdered hydrophobic material in the tube upon completion of the connection of tip portion 24 and connecting portion 26 thereto as by injecting the material thereinto by means of a suitable injector nozzle 27. Upon filling of the passage with the hydrophobic material, the tip openings are suitably closed as by taping and the powder compacted by vibrating the assembly. Alternatively, the powder may be compacted by centrifuging the assembly with the tip outermost. The packed tube may then be suitably heated as by placement in a suitable oven 28, as shown in FIG. 7, to fuse the coating layer 12 to the tube inner surface. The powdered hydrophobic material remaining unbonded to the tube surface is then suitably removed as by passing a stream of air through the catheter to complete the manufacturing operation. As shown in FIG. 8, a suitable air nozzle 29 may be inserted into the connector portion 26 of the catheter to blow cool air through the catheter and thereby quickly set the coating 12.

Still another method of manufacturing the catheter construction 10 is to place the tube 15 with the tip 24 and connector 26 attached thereto in a body of liquid 30 in a suitable tank 31. Liquid 30 may comprise a solution of the coating material in a volatile vehicle and a small percentage of binder. Upon removal of the structure from the tank, the vehicle may be suitably evaporated leaving the desired bonded coating thereon.

Still further, as shown in FIG. 6, the hydrophobic material may be secured to the tube wall surface 18 by firstly applying a layer of suitable bonding material or adhesive to the surface 18 by injecting the adhesive into the catheter through a suitable injection nozzle 32 as shown in FIG. 6. The hydrophobic material may then be passed through the tube to form a coating thereof on the layer 33 of adhesive material previously deposited. The adhesive is then caused to set to complete the manufacture. The provision of the hydrophobic material in the adhesive coated tube may be effected by the packing of the material therein, as shown in FIG. 4, with the subsequent removal of the excess nonbonded hydrophobic material as by flowing air through the tube, as shown in FIG. 8.

Specific examples of methods of forming the catheters are as follows:

EXAMPLE I

A vinyl tube was packed with hydrophobic Silanox material and vibrated in a vertical position to compact the material uniformly throughout the tube. The tube was then heated for a period of 20 minutes in an oven heated to a temperature of 340.degree. F. The tube was then removed and allowed to cool to room temperture whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE II

A vinyl tube was packed with hydrophobic Silanox material and vibrated in a vertical position to compact the material uniformly throughout the tube. The tube was then heated for a period of 20 minutes in an autoclave in a steam atmosphere at 340.degree.F. under a pressure of 35 p.s.i. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE III

A vinyl tube was packed with hydrophobic Silanox material and the material then compacted with a rod. The tube was then heated for a period of 10 minutes in an oven heated to a temperature of 340.degree.F. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE IV

A tube was coated with a film of adhesive by passing a solution of 5% thermoplastic polyurethane polymer in 95% methyl ethyl ketone, the polyurethane polymer comprising a No. 5715 B. F. Goodrich Co. Estane material. The tube was then filled with the hydrophobic Silanox material and vibrated in a vertical position. The packed tube was then heated to 200.degree.F. for a period of 20 minutes. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE V

A vinyl tube was coated with a film of adhesive by passing a solution of 50% thermoplastic polyurethane polymer in 50% benzene, the polyurethane polymer comprising B. F. Goodrich Co. Vulcalock material, and dried for 12 hours. The tube was then filled with the hydrophobic Silanox material and vibrated in a vertical position. The packed tube was then heated to 200.degree.F. for a period of 20 minutes. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE VI

A latex rubber tube was coated with a film of adhesive by passing a solution of 50% thermoplastic polyurethane polymer in 50% benzene, the polyurethane polymer comprising B.F. Goodrich Co. Vulcalock material, and dried for 12 hours. The tube was then filled with the hydrophobic Silanox material and vibrated in a vertical position. The packed tube was then heated to 200.degree.F. for a period of 20 minutes. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE VII

A latex rubber tube was packed with hydrophobic Silanox material and vibrated in a vertical position to compact the material uniformly throughout the tube. The tube was then heated for a period of 20 minutes in an autoclave in a steam atmosphere at 370.degree.F. under a pressure of 37 p.s.i. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

EXAMPLE VIII

A latex rubber tube was coated with a film of adhesive by passing a solution of 5% thermoplastic polyurethane polymer in 95% methyl ethyl ketone, the polyurethane polymer comprising a No. 5715 B. F. Goodrich Co. Estane material. The tube was then filled with the hydrophobic Silanox material and vibrated in a vertical position. The packed tube was then heated to 200.degree.F for a period of 20 minutes. The tube was then removed and allowed to cool to room temperature whereupon the loose Silanox material was removed by passing an air stream therethrough.

The adhesive materials may be modified to vary the thickness thereof. Further, the Silanox may be dissolved in suitable adhesive materials so as to provide both the bonding and hydrophobic materials in a single layer. The treating of the tubing in a liquid, as shown in FIG. 5, may comprise a step of utilizing bonding material as the liquid 30 and subsequently treating the bond coated structure with the powdered hydrophobic material. In the embodiment of FIG. 4, the nozzle 27 may provide the powdered hydrophobic material in a stream of hot air which effects the desired heating of the inner surface 18 of the tube to permit adherance and bonding of the carried hydrophobic material thereto with a continuous flow of the hot air stream through the tubing. Such a method of coating the tubing presents an advantage in that the entire tube is not heated and thereby maintains the tubular configuration.

Alternatively, hot air can be passed from the nozzle 27 prior to flowing of the powdered material therethrough so as to effect a preheating of only the inner surface portion 18 with the powdered material being delivered subsequently thereto at a relatively low pressure and at a lower temperature. As soon as sufficient material is adhered to the surface 18, a stream of cool air may be flowed through the tube to complete the setting of the coating.

The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

Claims

I claim:

1. A catheter construction providing extended blockage-free use, comprising:

a flexible tubular catheter element having an inlet opening at one end for receiving body fluids and an outlet opening at the opposite end for discharging body fluids, said catheter being formed of elastomeric polymeric material; and

a physiologically compatible coating effectively retained on the inner surface of said tubular catheter of hydrophobic Silanox.

2. The catheter construction of claim 1 wherein said tubular catheter element is formed of vinyl thermoplastic resin.

3. The catheter construction of claim 1 wherein said tubular catheter element is formed of latex rubber.

4. The catheter construction of claim 1 wherein the outer surface of the catheter element adjacent said inlet opening is provided with said hydrophobic coating.

5. The catheter construction of claim 1 wherein the outer surface of the catheter element is provided with said hydrophobic coating.

6. The catheter construction of claim 1 wherein said coating is thermally bonded to said catheter element.

7. The catheter construction of claim 1 wherein said coating is adhesively bonded to said catheter element.

8. The catheter construction of claim 1 wherein a polyurethane coating is provided on said inside surface of the catheter element and said hydrophobic coating is provided on the inside surface of said polyurethane coating.

9. The catheter construction of claim 1 wherein said tubular catheter element is formed of a synthetic thermoplastic resin.

10. The catheter construction of claim 1 wherein said tubular catheter element is provided with a thermally set adhesive coating on said inner surface and said hydrophobic material is bonded to said catheter element.