The present invention relates to a respiratory interface device for delivering a gas to a user (50), comprising: &mdasha connection interface (24) for connecting a hose to deliver gas to the user (50), &mdasha cushion (12) that is adapted to contact a face of the user (50) and to surround at least a part of a nose and/or a mouth of the user (50), and&mdashan inflatable support structure (14) for holding the cushion (12).