Measurement of VO2, VCO2, and evaporative water loss with a flow-through mask

Equations for the calculation of VO2, VCO2, and evaporative water loss were derived for use of a paramagnetic gas analyzer with a flow-through respirometry system and an open or closed mask. The magnitude of errors involved in the determination of VO2 with no CO2 absorbent are small (+/-3%) but may be greater if no H2O absorbent is used, unless an appropriate correction is made for evaporative water loss. Data collected for hummingbirds (Selasphorus sasin) and monitor lizards (Varanus gouldii) indicate the validity of the technics described for the measurement of RQ and evaporative water loss and demonstrate the use of paramagnetic gas analyzers in monitoring respiratory patterns.