Systems and methods for metabolic monitoring

A method for metabolic monitoring comprising:

• collecting, with an interface appliance, exhaled gas from nasal airways of a subject;
• receiving at least a portion of the exhaled gas from the interface appliance in a mixing chamber operatively connected with the interface appliance;
• receiving, from a plurality of sensors, output signals related to one or more gas parameters related to inhaled gas and exhaled gas by the subject during one or more breaths;
• determining, with one or more physical computer processors, a flow rate of gas in the interface appliance during the one or more breaths based on the output signals from the sensors;
• determining, with the one or more physical computer processors, pressure changes near a mouth of the subject during the one or more breaths based on the output signals from the sensors to detect mouth breathing of the subject;
• determining, with the one or more physical computer processors, concentration measurements of oxygen (O2) and carbon dioxide (CO2) of the portion of the exhaled gas in the mixing chamber based on the output signals from the sensors, and discarding concentration measurements corresponding to mouth breathing;
• and
• determining, with the one or more physical computer processors, a rate of oxygen consumption (VO2) and carbon dioxide production (VCO2) of the subject based on the determined flow rate of gas, the determined carbon dioxide concentration of the exhaled gas in the mixing chamber, and the determined oxygen concentration of the exhaled gas in the mixing chamber.

A system for metabolic monitoring comprising:

• means for collecting exhaled gas from nasal airways of a subject;
• means for receiving at least a portion of the exhaled gas from the means for collecting exhaled gas;
• sensing means for outputting signals related to one or more gas parameters related to inhaled gas and exhaled gas by the subject during one or more breaths;
• means for determining a flow rate of gas in the means for collecting exhaled gas during the one or more breaths based on the output signals from the sensing means;
• means for determining pressure changes near a mouth of the subject during the one or more breaths based on the output signals from the sensing means to detect mouth breathing of the subject;
• means for determining concentration measurements of oxygen (O2) and carbon dioxide (CO2) of the portion of the exhaled gas in the means for receiving at least a portion of the exhaled gas based on the output signals, and for discarding concentration measurements corresponding to mouth breathing;
• and
• means for determining a rate of oxygen consumption (VO2) and carbon dioxide production (VCO2) of the subject based on the determined flow rate of gas, the determined carbon dioxide concentration of the exhaled gas in the means for receiving at least a portion of the exhaled gas, and the determined oxygen concentration of the exhaled gas in the means for receiving at least a portion of the exhaled gas.