WO2000076564A1

WO2000076564A1 - Medical tubing

Info

Publication number: WO2000076564A1
Application number: PCT/US2000/016682
Authority: WO
Inventors: David S. Utterberg
Original assignee: DSU Medical Corp
Current assignee: DSU Medical Corp
Priority date: 1999-06-16
Filing date: 2000-06-14
Publication date: 2000-12-21
Anticipated expiration: 2001-12-16
Also published as: AU6051600A

Abstract

A medical fluid flow set comprises tubing (24) connected to other set components such as connectors, pump tubing, air removal chambers, and the like. The tubing comprises flexible plastic material having a Shore A durometer value of about 60 to 85. The flexible plastic tubing (24) is free of chlorine, and has at least a main tubular layer portion (28) which is free of urethane. The tubing has a resistance to kinking which is comparable to the kink resistance of comparable medical grade plasticized polyvinyl chloride tubing, and is free of tackiness to such a degree that it permits reversible sealing and unsealing by means of a pressure clamp. Specifically, the flexible plastic material (28) may comprise poly(ethylene methyl acrylate) or poly(styrene-butadiene).

Description

MEDICAL TUBING

BACKGROUND OF THE INVENTION

Flexible tubing is used throughout medicine for transfer of fluids. To date, the most popular material for medical tubing is plasticized polyvinyl chloride (PVC). However, that material has been deemed undesirable by some because of the presence of plasticizers which can leach out of the PVC plastic. Also, the PVC monomer itself has been viewed by some as undesirable. Other candidates for medical tubing include polyolefins and poly(ethylene-vinyl acetate). However, these materials are not readily solvent bondable or easily printed on.

Polyethylene tubing and poly(ethylene-vinyl acetate) also exhibit problems of being excessively kink-forming on tube bending, when compared with plasticized polyvinyl chloride.

Polypropylene tubing is too tacky, if the material is of low enough molecular weight to be flexible, to be used in conjunction with a pressure clamp such as a roller clamp or squeeze clamp. Thus, inside and outside extrusions of other plastic must be provided over such polypropylene tubing to avoid this problem.

Aliphatic polyurethanes can have good physical characteristics, but the material is too expensive to be an effective competitor for use as medical tubing. Thus, there is a need for a flexible plastic medical tubing which is of low cost, but is solvent bondable, resistant to kinking, and non-tacky. Similarly, there is a need for such a material in the manufacture of flexible chambers such as pressure pillows, as are used in hemodialysis sets and the like.

By this invention, medical tubing is provided which addresses the above disadvantages, and is also capable for use in manufacturing flexible chambers for use in medical sets such as pressure pillows.

DESCRIPTION OF THE INVENTION A medical fluid flow set comprises tubing connected to other set components. The tubing has at least a first extrusion layer which forms at least an inner lumen. The first extrusion layer comprises a flexible plastic material having a Shore A durometer of 60-85, the plastic material being substantially free of chlorine, acetate, and urethane. Preferably, the first extrusion layer comprises a hydrocarbon material which is other than polyethylene or polypropylene. Preferred materials in accordance with this invention define an inner lumen which is sufficiently free of tackiness to permit reversible sealing and unsealing by means of a flow control or a pinch clamp in the manner of conventional PVC tubing, but avoiding the disadvantages of PVC. For example, flexible polypropylene materials tend to self-weld shut 5 when the inner lumen is squeezed closed by a pinch clamp or the like, thus greatly reducing the utility of such materials for tubing in medical fluid flow sets.

Also, the plastic material of the first extrusion layer has a resistance to kinking on the order of the kink resistance of medical grade polyvinylchlo de as typically used in medical tubing, while avoiding the disadvantages of PVC, particularly by being free of leachable 0 plasticizers. Specifically, the tubing should not collapse when formed into a loop (without significant tension) of 60 mm diameter, which provides a bending radius of 30 mm. Such tubing may be bent into a loop of about 270° arc for the test, and then inspected for collapse.

Preferably, the lumen defining first extrusion layer is one of the following: (1) poly(ethylene-methyl acrylate) which is a copolymer of ethylene and methyl acrylate, s preferably with a methyl acrylate content of about 15 to 35 mol. percent, having the desired softness of a Shore A durometer of less than 85, but preferably no less than about 60-70.

This material is sold by the Chevron Chemical Company under the Trademark EMAC.

(2) Another preferred candidate for the lumen-defining, first extrusion layer used in the tubing of this invention is poly(styrene-butadiene) having a butadiene content that is o sufficient to provide a desired durometer of less than 85 on the Shore A scale and preferably at least about 60-70. This material also shares in the advantages described above when used as medical tubing, to achieve the desired objective of this invention of effective medical tubing which is free of covalently bonded chlorine and plasticizers which may leach into the medical materials carried by the tubing, plus the other stated objectives. A preferred material 5 for this use is available from the Phillips Chemical Company under the Trademark K-Resin, having the specified Shore A durometer and preferably a durometer of 70-80..

If desired, to enhance the bonding properties of tubing used in this invention to other components of medical sets, the tubing may be coextruded with a typically relatively minor layer, either on the outer surface of the tubing or the lumen wall of the tubing. Preferably, the o thickness of this layer has a cross-sectional area that is no more than about 30% of the entire cross-sectional area of the tubing, excluding the open, central lumen. Generally, this auxiliary layer for bonding purposes may be an aliphatic polyurethane material such as Estane from the B.F. Goodrich Company, and may typically have a thickness of about 0.001 to 0 02 inch This can facilitate solvent bonding to other materials comprising polyvinyl chloride, glycol-modified polyesters such as PETG or PCTG, polyethylene, polymethyl methacrylate (PMMA), polystyrene, poly(styrene-butadιene) or the like, and may be particularly applied to the EMAC tubing, to facilitate their versatility of solvent bonding to other materials

Preferred materials of EMAC may contain from about 22 to 34 mol percent methyl acrylate units, with essentially the balance being ethylene units

Specifically, such tubing, having an outer layer of aliphatic polyurethane about 0 008 inch thick, may be solvent bonded with cyclohexanone, methyl ethyl ketone, or any other conventional solvent bonding agent to various flow-through connectors as part of the tubing components, such as an end connector for connection to a dialyzer, a fistula set or the like, and/or a connector which connects to a de-bubbling chamber, a pump, roller pump tubing, a pressure pillow, a branch line connector, or the like Particularly, connectors to which the tubings are attached may be made from poly(styrene-butadιene) with a hardness greater than about 80 Shore A durometer, and/or a chamber made of poly(styrene-butadιene) having a Shore A durometer of less than 90 for a desired softness, coupled with a good solvent bond

Thus, medical tubing is provided for use in medical sets and the like, plus flexible chambers such as pressure pillows if desired, in which the plastic material exhibits the advantages of conventional PVC without disadvantages thereof

DESCRIPTION OF THE DRAWINGS In the drawings, Fig 1 is a plan view of an arterial set for hemodialysis constructed in accordance with this invention, and

Fig 2 is an enlarged, perspective view of a section of tubing of the set of Fig 1 , with a section taken through line 2-2 of Fig 1

DESCRIPTION OF SPECIFIC EMBODIMENTS Referring to the drawings, arterial blood set 11 is generally of conventional design for such blood sets which are in conventional use in the field of hemodialysis, hemoperfusion, and the like, except as otherwise described herein While arterial set 11 is specifically shown, it is contemplated that this invention can be applied to any of the large variety of medical sets which involve flow tubing, particularly those which are utilized for the transport of blood such as venous sets for hemodialysis and the like Also, sets for the transport of intravenous solution, peritoneal dialysis solution, and the like may utilize this invention Set 11 comprises various connected lengths of flexible medical tubing 12, 13, 13a, 14, 24, with various components connected between the tubing ends, such as bubble trap chamber 10 having various branch tubings 8 for connection to a pressure monitor of the like, and roller pump tubing 15 connected at each end by branch connectors 16, 16a, specifically of a design shown in Utterberg U.S. Patent No. 5,360,395, and having branch connection tubings 8a for pressure monitoring or the addition of heparin, saline solution, and the like. Also, a pressure pillow 17 may be provided, as well as an injection port 18 and a squeeze clamp 19, all in generally conventional manner. Arterial blood set 11 carries connectors 20, 22 of conventional design at each end, for respective connection to a dialyzer and to a fistula set, for example, which is in connection with the arteriovenous system of a patient.

In accordance with this invention, tubings 12, 13, 13a, 14 and 24 each comprise a length of extruded plastic which is free of leachable plasticizer and chlorine, but is substantially as kink resistant as PVC tubing, particularly being capable of not kinking when bent about a 30 mm radius, and being solvent bonded at tubing ends to the various connected devices such as connectors 20, 22, chamber 10, pump tubing 15, pressure pillow 17, and injection site 18. The lumen-defining, flexible tube 24, and the other tubes, may have any desired dimension and wall thickness, although in the particular embodiment the wall thickness may be on the order of 0J to 0.01 inch, and may each comprise a copolymer of ethylene and methyl acrylate with a methyl acrylate content of about 20 mol percent (specifically Chevron SP1257, having a melt index of 2 grams/10 mins.).

Tubing 24 (and any of the other tubings 12, 13, 13a, 14) may, like tube 24, define a tube portion 28 made of the ethylene-methyl acrylate copolymer as described above, defining a lumen 26. If desired, tubing 24 and the other tubings may comprise a coextrusion, with an outer, thinner extruded layer 30 of B.F. Goodrich Estane, which is an aliphatic polyurethane and is present in any convenient thickness, which thicknesses are preferably no more than about 30 percent of the entire cross-sectional area of tubing 24, excluding open lumen 26. More specifically, it is generally preferred for the thickness of outer layer 30 to be on the order of 0.003 to 0.008 inch. As previously described, this outer layer of aliphatic polyurethane facilitates the respective connection, for example, of the ends of tubing 24 with chamber 10 and connector 20, which chamber and connector may be made of polyethylene, Phillips

Chemical K resin, or the like. This connection can be easily made by conventional solvent bonding. Similarly, solvent bonding of the ends of tube 12 to connector 16a and pressure pillow 17 can be effected. Tubing 13 can likewise be solvent bonded to pressure pillow 17 and injection site 18, while tubing 13a can be solvent bonded to injection site 18 and connector 22, this being facilitated in each case by the outer aliphatic polyurethane layer 30. If desired, pressure pillows 17 can be made of the same or a similar grade of poly(ethylene methyl acrylate) to provide plasticizer-free, desirable characteristics.

Alternatively, tubing lengths 12, 13, 13a, 14, and 24 may be made of polystyrene- butadiene) or Phillips Chemical K resin, having a durometer about 80 on the Shore A scale.

If desire an inner or an outer coating of another plastic to facilitate bonding may be provided. However, poly(styrene-butadiene) has good bonding characteristics on its own to many plastic materials, which are suitable for manufacture of the various components used in sets such as connectors 20, 22, chamber 10, connectors 16, 16a and the like. Thus, auxiliary bonding layers may not be needed with poly(styrene-butadiene) or K resin tubing.

The above has been offered for illustrative purposes only, and is not intended to limit the scope of the invention of this application, which is as defined in the claims below.

Claims

THAT WHICH IS CLAIMED:

1. A medical fluid flow set which comprises tubing connected to other set components, said tubing having at least a first extrusion layer forming at least the inner lumen, said layer comprising a plastic materials having a Shore A durometer of 60-85 and being substantially free of chlorine, acetate, and urethane, and being other than polyethylene or polypropylene, and said inner lumen being sufficiently free of tackiness to permit reversible sealing and unsealing by means of a flow control or pinch clamp, and said tubing having a resistance to kinking when coiled into a loop of 30mm bending radius.

2. The medical set of Claim 1 in which said tubing comprises at least an inner lumen or an outer surface capable of solvent bonding with plastics selected from the group consisting of polyvinyl chloride, PETG, PCTG, PMMA, polystyrene, poly(styrene-butadiene) and the like.

3. The medical set of Claim 2 in which said first extrusion comprises poly(styrene-butadiene), with no other co-extrusion layer(s). 4. The medical set of Claim 3 which can be autoclave sterilized.

5. The medical set of Claim 3 in which at least one of said components is made from poly(styrene-butadiene) having a Shore A durometer less than about 100.

6. The medical set of Claim 1 in which said components are made from said plastics but the connections are not solvent bonded to said tubing. 7. The medical set of Claim 2 in which said tubing is reversibly clamped and undamped by a pinch clamp.

8. The medical set of Claim 2 in which said first extrusion comprises poly(ethylene methyl acrylate) polymer with from 20 to 34 mol. percent of methylacrylate units. 9. The medical set of Claim 8 in which said tubing is reversibly clamped and undamped by a pinch clamp.

10. The medical set of Claim 8 in which a second extrusion layer of a different plastic from the first extrusion layer forms the outer surface of said tubing and said second layer comprises a plastic materials capable of solvent bonding with plastics selected from the group consisting of polyvinyl chloride, PETG, PCTG, PMMA, polystyrene, and polystyrene- butadiene), the cross-sectional area of said second extrusion layer comprising no more than 30% of the cross-sectional wall area of said tubing. 11 The medical set of Claim 10 in which said second extrusion layer is an aliphatic polyurethane

12 The medical set of Claim 8 in which said tubing is connected at one end to a connector by solvent bonding 13 The medical set of Claim 8 in which said tubing is connected at one end to a connector by means other than solvent bonding

14 The medical set of Claim 1 in which said tubing is connected to a chamber comprising poly(styrene-butadιene) of Shore A durometer less than about 100

15 The medical set of Claim 1 in which said first extrusion layer of the tubing comprises no less than 70% of the cross-sectional wall area of said tubing, excluding the lumen defined within said tubing

16 The medical set of Claim 1 in which said plastic material is a hydrocarbon

17 A medical fluid flow set which comprises tubing connected to other set components, said tubing having at least a first extrusion layerforming at least an inner lumen, said layer consisting essentially of flexible poly(styrene-butadιene) which has a Shore A durometer of 60-85, said inner lumen being sufficiently free of tackiness to permit reversible sealing and unsealing by means of a pinch clamp, said tubing having a resistance to kinking when coiled into a circle of 30 mm bending radius

18 The medical fluid flow set of Claim 17 in which said first extrusion layer comprises substantially the entire tubing

19 The medical fluid flow set of Claim 17 in which said Shore A durometer is 70- 80

20 The medical fluid flow set of Claim 17 in which said tubing is connected at at least one end to a connector by solvent bonding 21 The medical set of Claim 17 in which said tubing is connected to a chamber comprising poiy(styrene-butadιene) of Shore A durometer less than 100

22 A medical fluid flow set which comprises tubing connected to other set components, said tubing having at least a first extrusion layerforming at least an inner lumen, said layer consisting essentially of flexible poly(ethylene methyl acrylate) which has a Shore A durometer of 60-85, said inner lumen being sufficiently free of tackiness to permit reversible sealing and unsealing by means of a pinch clamp, said tubing having a resistance to kinking when coiled into a circle of 30 mm bending radius

23. The medical fluid flow set of Claim 22 in which said first extrusion layer comprises substantially the entire tubing.

24. The medical fluid flow set of Claim 22 in which said Shore A durometer is 70-