Patient interface and components thereof

A patient interface comprising:

• a plenum chamber pressurisable to a therapeutic pressure of at least 4 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;
• the heat and moisture exchanger positioned within the plenum chamber, the heat and moisture exchanger comprising:
• a body constructed from a permeable, nonwoven composite formed with a fibrous material, the body having a first surface formed as a first planar surface and a second surface formed as a sidewall oriented substantially perpendicularly to the first surface;
• a passageway formed as a hole extending within the fibrous material between the first surface and the second surface, the fibrous material forming a wall of the passageway;
• 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 the patient's head;
• and
• wherein the body includes a first impedance and the passageway includes a second impedance less than the first impedance;
• wherein the fibrous material configured to absorb water vapor from exhaled air;
• wherein the permeable, nonwoven composite of the body configured to transfer the absorbed water vapor to inhaled air and increase the humidity of the flow;
• and
• wherein the passageway is elbow shaped and extends along two axes.