Control for a demand cannula

A control means for regulating the communication of pressurized breathable fluid from a storage container to a recipient, comprising:

• a housing having a plenum chamber, a distribution chamber, a control chamber, a sensing chamber, a relief chamber, a first outlet port and a second outlet port, said plenum chamber being connected to a storage container of pressurized breathable fluid through a first passageway, said control chamber being connected directly to said first passageway through a control passage, said sensing chamber being connected to said first outlet port by a second passageway, said distribution chamber being connected to said plenum chamber through a distribution passage and to said second outlet port through a third passageway, said control chamber being connected to said relief chamber through a relief passage, said relief chamber including means for relieving pressure accumulated therein, said housing having a plurality of orifices varied flow rate located in said first passageway downstream of the connection between said control passage and said first passageway for connecting the storage container with said plenum chamber;
• means adapted for connection to the nasal passages of a recipient;
• a first conduit connected to said first outlet port at one end and to said means adapted for connection to the nasal passages of the recipient;
• a second conduit connected to said second outlet port at one end and to said means adapted for connection to the nasal passages of the recipient at the other end;
• actuator means connected to the first passageway for permitting said pressurized breathable fluid to flow from the storage container into said first passageway;
• selector means for choosing a flow rate orifice from said plurality of orifices which allows continual communication of a fixed quantity of breathable fluid from said first passageway into the plenum means corresponding to the metabolic needs of a recipient;
• first wall means located in said housing for separating said control chamber from said distribution chamber and for controlling flow of fluid from said distribution chamber through said distributor passage;
• and
• second wall means located in said housing for separating said sensing chamber from said relief passage for controlling flow from said relief pasaage, said second wall means responding to an exhalation pressure communicated from the nasal passages through said first conduit to said sensing chamber to seal said relief passage causing the pressurized breathable fluid in the control passage to flow into said control chamber and urge said first wall means toward said distribution passage to interrupt the flow of breathable fluid therethrough and allow a fixed quantity of pressurized breathable fluid to flow into said plenum chamber, said second wall means responding to an inhalation pressure communicated from the nasal passages through said first conduit to said sensing chamber to allow the pressurized breathable fluid in said control chamber to flow through said relief passage into said relief chamber and permit said fixed quantity of pressurized breathable fluid to communicate to the nasal passages of the recipient through said second conduit to meet an inhalation demand.