Functional Residual Capacity and Respiratory Nitrogen Excretion of Dogs

Abstract

Functional residual capacity (FRC) of supine, anesthetized, tracheotomized dogs was determined to be 24.9 ml/kg body weight by the standard open-circuit method after correction for N excretion, and 29.7 by the closed-circuit method. Direct measurement of FRC by expelling the gas content of the lungs into a spirometer gave a mean of 31.4, which was significantly greater than the open-circuit method, but not the closed-circuit method. Respiratory N excretion during 7 minutes of O2 breathing by dogs was 6.4 ml/kg.