A tube for carrying gas in medical circuits is formed from a helical elongate hollow body 203 and a reinforcement portion 205 spirally positioned between the adjacent turns of the elongate hollow body. The elongate hollow body and the reinforcement may be unitary or they may be separate members that have been joined together. The reinforcement may be less flexible than the hollow body and may be wider proximal the lumen of the tube than it is at a radial distance from the lumen. The first elongate member may form, in longitudinal cross-section, a series of bubbles with a flattened surface at the lumen, the bubbles being separated by gaps over the reinforcement portion. Where the reinforcement portion is integral with the elongate hollow member, it may be formed by the joining together of reinforcement parts on each side of the elongate hollow member. The construction is intended to provide thermal insulation whilst permitting bending without occlusion.
