STUDIES ON THE INTRAPULMONARY MIXTURE OF GASES. I. NITROGEN ELIMINATION FROM BLOOD AND BODY TISSUES DURING HIGH OXYGEN BREATHING

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Abstract
I. The 1st paper of the series studies the excretion of N from the body during breathing of pure O2. In normal subjects at rest, an avg. of 220 cc. of N is excreted in 7 min. This confirms the work of earlier investigators. II. The 2d paper presents the results of exptl. analysis of the closed-circuit method of residual air measurement. By the usual technique pure O2 is re-breathed from a small spirometer until intra-pulmonary air and spirometer air are supposedly mixed, and the lung volume calculated from analysis of the inert gas (N) content of the mixed (spirometer) sample. By a reversed procedure, in which the lungs are first filled with O2, then subsequently mixed with air (79% N) in a closed circuit, it is demonstrated that even mixture does not take place between pulmonary and spirometer air, in many em-physematous subjects; and that residual air vols. as cal-culated are therefore erroneous, in these subjects. III. The 3d paper describes an open circuit method for detn. of functional residual air. An alveolar air sample is taken; the subject then breathes pure O2 for 7 mins., and the expired air is collected in a large gasometer; another alveolar air sample is taken at the end of the 7-min. period of O breathing. From the N concs. of these 3 samples, the vol. of functional residual air can readily be calculated. This method, while not free from all error, is shown, both theoretically and experimentally, to be more accurate than the closed-circuit methods.