Method and apparatus for estimation of resting respiratory quotient

摘要

A method and apparatus for determining a user's Respiratory Quotient (RQ) using just measured O₂ and CO₂ concentrations without use of a flow meter. The RQ is determined by measuring the user's real-time inspired O₂ concentration (INS O2) and end tidal O₂ concentration (ETO2) and measuring the user's real-time inspired CO₂ concentration (INS CO2) and end tidal CO₂ concentration (ETCO2), and then determining the user's RQ from the measured INS O2, ETO2, INS CO2, and ETCO2 values in accordance with the following equation: RQ=(ETCO2−INS CO2)/(INS O2−ETO2). In order to avoid error introduced by the flow rate, the measurement steps are preferably performed while the user is in a resting condition. Also, ETCO2 is preferably measured as the maximum CO₂ value in a breath cycle of the user, while INS CO2 is preferably measured as the minimum CO₂ value in a breath cycle of the user. Similarly, ETO2 is preferably measured as the minimum O₂ value within a breath cycle of the user, while INS O2 is measured as the maximum O₂ value within a breath cycle of the user. On the other hand, the values of INS CO2 and ETCO2 also may be determined in accordance with the invention by analysis of a CO₂ waveform of a breath cycle of the user and the values of INS O2 and ETO2 determined by synchronizing timing of the O₂ waveform of a breath cycle of the user with the CO₂ waveform and sampling INS O2 and ETO2 values simultaneously with sampling of complementary CO₂ values determined by analysis of the CO₂ wavefomm. The RQ measuring device may include the oxygen and CO₂ sensors in a mainstream or sidestream configuration.