Patent ID: 8485181

Claim:
A method of controlling breathing of a patient, wherein air is supplied to the patient using a patient interface device coupled to a pressurized air supply device using a respiratory conduit that includes first and second controllable openings and first and second volume connectors configured as partial dead space volumes positioned along the length of the respiratory conduit, the method comprising: determining a rate of production of carbon dioxide generated by the patient; measuring a rate of flow and a concentration of carbon dioxide at each of the controllable openings; adjusting sizes of each of the first and second controllable openings based on the measuring to control a rate of excretion of carbon dioxide from the respiratory conduit to the ambient air and a concentration of carbon dioxide in blood of the patient, wherein the adjusting is configured to allow a range of amounts of carbon dioxide excreted from the respiratory conduit to the ambient air to be substantially equal to a range of production of carbon dioxide by the patient during a period of time; and adjusting sizes of at least one of the volume connectors based on at least one of the determining and the measuring; adjusting the first controllable opening to allow an escape of an amount of carbon dioxide to the ambient air that is lower than or equal to the amount of carbon dioxide produced by the patient during a period of time; adjusting the second controllable opening to allow an escape of an amount of carbon dioxide to the ambient air that is based upon i) the amount of carbon dioxide allowed to escape from the first controllable opening, and ii) a maximum total amount of carbon dioxide produced by the patient during a period of time; and wherein air supplied to the patient includes a mixture of air supplied by the air supply device and carbon dioxide generated by the patient.