A method of providing a gas flow for delivery to an airway of a subject, which includes the steps of generating a gas flow that facilitates respiration of the subject, receiving a selection of an adjustment from the subject for a property of the gas flow, and making the selected adjustment to the gas flow if the gas flow will remain within a predetermined range after the selected adjustment is made. The method also includes the step of declining to make the selected adjustment to the gas flow if the gas flow would not remain within the predetermined range after the selected adjustment.
