Nasal cannula

A nasal cannula arrangement for use as part of a system for delivering respiratory gas to a patient, said system of a type that has a gases source adapted to provide a stream of gases to one or more nares of the patient in use, and a delivery conduit that in use connects between the gases source and said nasal cannula arrangement, said nasal cannula arrangement comprising:

• a gases inlet manifold part adapted to form a fluid connection with the delivery conduit in use so that the stream of gases is delivered into said gases inlet manifold part,
• at least one nasal prong in fluid connection with said gases inlet manifold part and adapted to be inserted into the one or more nares of the patient, the stream of gases passing through said gases inlet manifold part and through said at least one nasal prong,
• said at least one nasal prong having a rear side and a front side, wherein said rear side is closer to the patient when in use and said front side is further from the patient when in use,
• said at least one nasal prong having a gases exit cut-out on a rear side of said at least one nasal prong, said gases exit cut-out having a cross-sectional area greater than a cross-sectional area of said at least one nasal prong at or close to a point of entry of the stream of gases to said at least one nasal prong, a plurality of edges of said gases exit cut-out conforming to a surface that substantially has a reverse S-shape, said reverse S-shape being aligned substantially vertically, said front side extending further upwards and rearwards than said rear side, said front side forming a guide wall that guides said stream of gases into a nasal passage of the patient when in use, and
• face mount parts extending laterally outward from said at least one nasal prong, said face mount parts being adapted to connect to a headgear assembly.