Dilution of alveolar gases during nitrous oxide excretion in man

Abstract

The effect of N2O excretion upon O2 and CO2 levels in man was studied during two different types of artificial respiration with air. When a constant inflating pressure type respirator was used, the average fall in end-tidal Pco2 was 2 mm Hg or 5%. The measured fall in alveolar Po2 could not be determined with confidence, although theoretical considerations indicate it to be greater than 5%. When the respirator was servo controlled by end-tidal CO2 in a manner closely analogous to the human central respiratory mechanism, with the Pco2 level thus held constant, the inflating pressure fell and the average arterial O2 saturation fell 2.8% (20 mm Hg, or a 21% fall). These results have been interpreted to reflect the influence of N2O excretion upon both alveolar O2 and CO2. Submitted on February 6, 1961