Breathing assistance apparatus

1. A nasal cannula for delivering respiratory gases to a patient's nares comprising:

a gases inlet configured to engage an inspiratory conduit;

a separate gases outlet configured to engage a separate expiratory conduit,

a hollow manifold chamber, said gases inlet and said gases outlet in fluid communication through said manifold chamber,

a pair of nasal prongs in fluid communication with said gases inlet and said gases outlet through said hollow manifold chamber,

said hollow manifold chamber configured internally to limit the deadspace of said nasal cannula substantially to the volume of said prongs and further configured internally to provide a low resistance path between said gases inlet and said gases outlet such that in use a portion of said respiratory gas flows continuously directly from said gases inlet to said gases outlet, said prongs juxtaposed directly in said low resistance path,

each of said prongs spaced equidistant from said gases inlet such that said respiratory gas is available to each of said prongs simultaneously, and

each of said prongs spaced equidistant from said gases outlet such that the potential for rebreathing expired gases is reduced.

2. A nasal cannula as claimed in claim 1 wherein said nasal cannula further has rod and a clip engagement for securing said cannula to a strap, said rod and clip arrangement comprising:

a cylindrical rod with two end connectors at or proximate each end, said connectors configured to receive a portion of said strap and to hold said strap relative to the rod, and

a clip connected to the cannula, said clip having at least two projecting members spaced to receive a segment of said rod and retain said clip in contact with said rod in such a manner that said rod is able to slide laterally and rotate about a longitudinal axis relative to said clip when engaged.

3. A nasal cannula as claimed in claim 2 wherein said strap includes an adjustable attachment to said rod.

4. A nasal cannula as claimed in claim 3 wherein said securement has a head covering bonnet adapted to at least partially cover the head of said patient, said bonnet having an elastic cuff to securely locate said bonnet on said patient head, and a securing strap for use in holding at least one of said inspiratory conduit or said expiratory conduit in a position on said bonnet against at least lateral movement, said securing strap connected with said bonnet on the outer surface thereof.

5. A nasal cannula as claimed in claim 4 wherein said bonnet is formed of a knit fabric in a tubular configuration, open at both ends, said securing strap is connected with said outer surface adjacent one of said ends, with an end closure mechanism connected with said outer surface adjacent the other of said ends, said end closure mechanism operable to hold the said knit fabric at said end in a closed, bunched together, condition.

6. A nasal cannula as claimed in claim 5 wherein said end closure mechanism is a lace or tie stitched to said cover.

7. A nasal cannula as claimed in claim 6 wherein said lace or tie is centrally secured to said cover to provide two arms, and said end closure mechanism further comprises a tightening toggle through which said arms pass, said tightening toggle slidable on said arms, said tightening toggle operable between at least two conditions, being biased to a pinch off condition in which said arms of said lace or tie are clamped within said toggle, said toggle manipulable to a free configuration in which said toggle may slide along said arms of said lace or tie.

8. A nasal cannula as claimed in claim 1 wherein said cannula also has a strap and a head securement,

said strap passing around the back of said patient's neck and engaging with said cannula below said prongs to form a strap engagement, and

said head securement located above said prongs and configured to engage at least one of said inspiratory conduit, or said expiratory conduit, or both and hold said conduit or conduits in position on said patient's head,

said strap engagement and said head securement securing said cannula in place on said patient.

9. A nasal cannula as claimed in claim 8 wherein said strap engagement and said head securement secure said cannula in place on said patient in such a manner that contact between said cannula and said patient occurs only at the patient's nares, except for said strap engagement and said head securement.

10. A nasal cannula as claimed in claim 1 wherein said manifold chamber is partially bisected by a partition, said partition creating a tortuous pathway for gases flowing through said manifold chamber between said inlet port and said outlet port, said nasal prongs juxtaposed in said tortuous pathway.