Medical Tube and Method of Formation

A method of forming a visually clear or transparent and manually flexible medical tube for in vivo transport of an aqueous fluid, the method of forming comprising:

• selecting a first polymeric material that is an aromatic or aliphatic polyether based polyurethane material having a selected structural stability;
• and
• selecting a second polymeric material that is a polypropylene material that is inert to aqueous fluids;
• selecting a third polymeric material that is elastomeric in nature and has visual clarity and is selected from one or more of ethylene vinyl acetate copolymers, ethylene acrylate copolymers, ethylene-acrylate maleic anhydride terpolymers, ethylene-acrylate glycidyl methacrylate terpolymers, and maleic anhydride grafted polypropylene
• co-extruding the selected first, second and third polymeric materials to form respectively adhered outer, inner and middle layers of the medical tube in a configuration such that the outer layer comprises at least 90% by weight of the first polymeric material, the inner layer comprises at least 90% weight of the second polymeric material and the middle layer comprises at least 90% by weight of the third polymeric material,
• the materials being selected so as to maintain the integrity of the tube against delamination and maintain its visual clarity or transparency after being subjected to one or more of ethylene oxide and gamma irradiation sterilization,
• wherein the medical tube has a central axial fluid flow passage defined by a radial inner wall surface of the inner layer through which aqueous fluid is transported, and wherein the tube does not visually delaminate after being submersed in water at 60 degrees C. for 72 hours and subsequently mechanically flattened by manual squeezing of the tube from its normal round in cross-sectional condition to a flattened or oval cross-sectional shape or condition.

A tube (10) adapted for in vivo transport of an aqueous fluid to a subject comprising an inner layer (3), a middle layer (2) and an outer layer (1),

• wherein the tube is formed by a co-extrusion process, the inner layer (3), middle layer (2) and outer layer (1) are concentric and the inner layer (3) and outer layer (1) are adhered to the middle layer (2) and thus adhered to each other, wherein
• the inner layer (3) comprises a polypropylene,
• the outer layer (1) comprises a cyclic olefin copolymer and
• the middle layer (2) is selected from one or more of ethylene vinyl acetate copolymers, ethylene acrylate copolymers, ethylene-acrylate maleic anhydride terpolymers, ethylene-acrylate glycidyl methacrylate terpolymers, and maleic anhydride grafted polypropylene.

A method of forming a visually clear or transparent and manually flexible medical tube for in vivo transport of an aqueous fluid, the method of forming comprising:

• selecting a first polymeric material that is an aromatic or aliphatic polyether based polyurethane material having a selected structural stability;
• and
• selecting a second polymeric material that is a polypropylene material that is inert to aqueous fluids;
• selecting a third polymeric material comprising an acrylate copolymer that is elastomeric in nature and has visual clarity and is selected from one or more of ethylene vinyl acetate copolymers, ethylene acrylate copolymers, ethylene-acrylate maleic anhydride terpolymers, ethylene-acrylate glycidyl methacrylate terpolymers, and maleic anhydride grafted polypropylene
• co-extruding the selected first, second and third polymeric materials to form respectively adhered outer, inner and middle layers of the medical tube in a configuration such that the outer layer comprises at least 90% by weight of the first polymeric material, the inner layer comprises at least 90% weight of the second polymeric material and the middle layer comprises at least 90% by weight of the third polymeric material,
• the materials being selected so as to maintain the integrity of the tube against delamination and maintain its visual clarity or transparency after being subjected to one or more of ethylene oxide and gamma irradiation sterilization,
• wherein the medical tube has a central axial fluid flow passage defined by a radial inner wall surface of the inner layer through which aqueous fluid is transported, and wherein the tube does not visually delaminate after being submersed in water at 60 degrees C. for 72 hours and subsequently mechanically flattened by manual squeezing of the tube from its normal round in cross-sectional condition to a flattened or oval cross-sectional shape or condition.