Method of forming a medical tube

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 polyethylene 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 selected from the group consisting of an ethylene ethyl acrylate copolymer, an anhydride grafted ethylene methyl acrylate copolymer, a copolymer of said acrylates or a mixture of two or more of the foregoing;
• co-extruding the selected first, second and third polymeric materials to form respectively adhered outer, inner and intermediate layers of the medical tube 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 intermediate 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 36 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.