Method and system for controlling breathing

A method for controlling flow of carbon dioxide to a patient during breathing, using a pressurized air supply device coupled to a patient interface device placed on the patient, the patient interface device is coupled to a carbon dioxide mixing device, which is coupled to the pressurized air supply device, the carbon dioxide mixing device includes first and second ventilation orifices in communication with the ambient air that are interchangeably connected with multiple dead spaces, wherein the first and second ventilation orifices control supply of carbon dioxide to the patient and volume of carbon dioxide in the multiple dead spaces, the method comprising:

• measuring airflow through each of the ventilation orifices;
• detecting a content of carbon dioxide in the measured airflow;
• adjusting airflow through each of the ventilation orifices based on the detecting of the concentration of carbon dioxide 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 allows 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;
• adjusting the first ventilation orifice 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 ventilation orifice 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 ventilation orifice, and ii) a maximum total amount of carbon dioxide produced by the patient during a period of time;
• and
• adjusting sizes of the multiple dead spaces based on the detection of the concentration of carbon dioxide and the adjusting of the airflow through each of the multiple ventilation orifices.

A method for controlling breathing of a patient using a respiratory conduit configured to be coupled to a patient interface device and a pressurized air generating device, wherein the conduit includes at least three air flow control devices positioned between the patient interface device and the pressurized air generating device and at least two volumes that function as partial dead spaces, wherein a first volume is positioned between a first air flow device and a second air flow device, and a second volume is positioned between the second air flow device and a third air flow device, the method comprising:

• receiving carbon dioxide in the conduit, wherein the carbon dioxide originates from an expiratory breath of the patient;
• and
• allowing escape of carbon dioxide from the at least three air flow control devices to ambient air in a range substantially equal to a range of carbon dioxide produced by the patient during a period of time;
• wherein a portion of the received carbon dioxide escapes from the first air flow control device to the ambient air and another portion of the received carbon dioxide travels through the first volume to the second air flow control device;
• wherein a part of the another portion of the received carbon dioxide escapes from the second air flow control device to the ambient air and another part of the another portion of the received carbon dioxide travels through the second volume to the third air flow control device;
• and
• wherein the another part of the another portion of the received carbon dioxide escapes from the third air flow control device to the ambient air.