US Patent 7353826 Sealing nasal cannula

An integrally molded ventilation interface includes a hollow bellows-like structure and two nasal prongs extending from a top surface of the bellows. A pair of headgear strap flanges can also be molded integrally with the ventilation interface. The nasal prongs provide a first sealing interface between an outer surface of the nasal prongs and an inner surface of the patient's nares. The bellows provides a second sealing interface between a top surface of the bellows-like structure and a bottom surface of a patient's nose. The headgear strap flanges provide a third sealing interface between the ventilation interface and a mustache region of the patient's face as well as a bottom surface of the patient's nose.