DISTRIBUTION OF RESPIRATORY GASES IN A CLOSED BREATHING CIRCUIT. I. IN NORMAL SUBJECTS

Abstract

When a normal individual breathes for several min. in a small closed circuit in which the O conc. is steadily decreasing, an equilibrium state is set up, in which the expired N conc. is less than the inspired N conc. This is due to the "storage" of earlier breaths in the lungs, with expired air consisting of mixed samples of the air, within the lungs, from many earlier breaths. Methods for determining residual lung vols. may be considerably in error, if correction is not made for the effects of this phenomenon.