Breathing apparatus detection and purging

1. A method of administering therapeutic gas containing nitric oxide to a patient, the method comprising:

detecting the presence or absence of a nasal cannula breathing apparatus at a connection port of a nitric oxide delivery apparatus, wherein the presence or absence of the breathing apparatus is detected by one or more of short range radio frequency identification (RFID), a light source/photodiode arrangement, a strain gauge, a proximity sensor and a bar code;

flowing therapeutic gas containing nitric oxide to at least one of a nasal cannula and one or more nares of the breathing apparatus if the breathing apparatus is determined to be connected to the nitric oxide delivery apparatus and not flowing therapeutic gas containing nitric oxide to at least one of the nasal cannula and the one or more nares of the breathing apparatus if the breathing apparatus is determined not to be connected to the nitric oxide delivery apparatus; and

purging the nasal cannula breathing apparatus during patient expiration with a purge volume greater than a volume of the one or more nares of the breathing apparatus and less than a total internal volume of the nasal cannula.

2. The method of claim 1 , further comprising providing an alert if the breathing apparatus is determined not to be connected to the nitric oxide delivery apparatus.

3. The method of claim 2 , wherein the alert includes one or more of an audible alert, a visual alert and a text alert.

4. The method of claim 1 , wherein the breathing apparatus is purged if the breathing apparatus is determined to be connected to the nitric oxide delivery apparatus after the breathing apparatus was determined not to be connected to the nitric oxide delivery apparatus.

5. The method of claim 4 , wherein the breathing apparatus is purged automatically without patient intervention.

6. The method of claim 1 , further comprising purging the breathing apparatus prior to administering the therapeutic gas containing nitric oxide.

7. The method of claim 1 , wherein detecting the presence or absence of a breathing apparatus comprises sending and receiving signals from the connection port and the breathing apparatus.

8. A method of administering therapeutic gas containing nitric oxide, the method comprising:

sensing inspiration of a patient;

during patient inspiration, delivering a pulse of therapeutic gas containing nitric oxide through a valve along a conduit and nasal cannula and subsequently through one or more nares of a breathing apparatus to the patient;

repeating the delivering a pulse of the therapeutic gas to provide successive deliveries;

measuring elapsed times between the successive deliveries of therapeutic gas to the patient;

determining that an elapsed time between successive deliveries of therapeutic gas exceeds a predetermined period of time;

sensing expiration of the patient; and

purging the breathing apparatus during patient expiration with a purge volume greater than a volume of the one or more nares of the breathing apparatus and less than a total internal volume of the nasal cannula.

9. The method of claim 8 , wherein purging the breathing apparatus comprises opening the valve to deliver a pulse of therapeutic gas during patient expiration.

10. The method of claim 8 , wherein one or more patient breaths are detected between the successive deliveries of therapeutic gas.

11. The method of claim 8 , wherein the elapsed time is reset when the breathing apparatus is purged.

12. The method of claim 8 , wherein the predetermined period of time is in a range from 5 seconds to 15 seconds.

13. The method of claim 8 , wherein the predetermined period of time is in a range from 1 to 10 breaths.