This invention relates to a patient interface, a system and/or method for providing a dedicated or sole inspiratory line or conduit for provision of inspiratory gases to a patient, and a dedicated or sole expiratory line or conduit for provision of expiratory 5 gases to a downstream device, where the inspiratory line or conduit is sealing engageable with the first of a user's nares and the expiratory line or conduit is sealing engageable with the second of the user's nares.
