Headgear tubing for a patient interface

A patient interface comprising:

• a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH2O above ambient air pressure, said plenum chamber including a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient;
• a seal-forming structure constructed and arranged to form a seal with a region of the patient's face surrounding an entrance to the patient's airways, said seal-forming structure having a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient's nares, the seal-forming structure constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient's respiratory cycle in use;
• and
• a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on a head of a patient, the positioning and stabilising structure comprising:
• at least one gas delivery tube to deliver the flow of air to the entrance of the patient's airways via the seal-forming structure, the at least one gas delivery tube being constructed and arranged to contact, in use, at least a region of the patient's head superior to an otobasion superior of the patient's head,
• wherein the at least one gas delivery tube includes a patient contacting portion and a non-patient contacting portion, the patient contacting portion being joined to the non-patient contacting portion along respective first and second edges of the gas delivery tube thereby forming corresponding first and second seams of the gas delivery tube such that the patient contacting portion is spaced from the non-patient contacting portion along a central portion of the gas delivery tube between the first seam and the second seam to form a tubular-shaped gas passageway to convey the flow of air,
• wherein the first seam and the second seam close off respective lateral sides of the gas passageway to prevent escape of the flow of air to atmosphere, and at least the first seam provides rigidity to the gas delivery tube,
• wherein the non-patient contacting portion includes a first textile outer layer, and the patient contacting portion includes a second textile outer layer,
• wherein the patient contacting portion has a substantially planar cross-sectional shape, wherein the non-patient contacting portion has a pre-determined non-planar cross-sectional shape when joined to the patient contacting portion, and wherein the non-patient contacting portion is resilient such that when subjected to external force the cross-sectional shape of the non-patient contacting portion is altered, and when the external force is released the non-patient contacting portion returns to the pre-determined non-planar cross-sectional shape, and
• wherein, when the non-patient contacting portion is joined to the patient contacting portion, the non-patient contacting portion is deformed elastically such that the non-patient contacting portion is biased towards a flatter shape than the pre-determined non-planar cross-sectional shape and imparts tension to the patient contacting portion.