The present invention relates to the field of continuous positive airway pressure (CPAP) therapy. The nasal continuous positive airway pressure device 100 comprises a neck region 200 connected to a mask or nasal prong； and an elongated flexible tube 300. The elongated flexible tube 300 comprises co-axial inner 310 and outer 320 tubes. The inner 310 and outer 320 tubes are spaced to define a first lumen 330 within the outer tube 320. A second lumen 340 is defined by the inner tube wall alone. The second lumen 340 is configured to be connected to an oxygen gas supply at the distal end 304 of the elongated flexible tube 300, and to the neck region 200 at the proximal end 302 of the elongated flexible tube 300. The first lumen 330 is configured to be connected to the neck region 200 at the proximal end 302 of the elongated flexible tube 300.
