Uptake of highly soluble gases in the epithelium of the conducting airways

Abstract

Short duration washin and washout experiments were carried out with the gases ether (diethyl ether), ethyl acetate and acetone in order to study the excretion behaviour in the lung of gases highly soluble in blood and tissues. Carbon dioxide (CO₂) was analyzed as a reference gas during the washout. The excretion values for acetone were generally the lowest, those for ether the highest, and intermediate ones were obtained for ethyl acetate. These results are in accord with the experimental data of others. Analysis of the washout curves shows that for acetone the volume of gas expired before the beginning of phase II is considerably smaller than found for CO₂ and ether. During washout, the slope of the alveolar plateau for acetone is negative for the first few breaths and becomes positive thereafter; however, it remains lower than the slopes for CO₂ and ether, which are always positive. These two phenomena occurring during washout clearly demonstrate that the acetone in the expired air must originate from the epithelial tissue lining the conducting airways. We conclude, therefore, that, in terms of gas transport, the conducting airways behave differently for poorly and highly soluble gases and this provides a physiological basis for the deviating excretion behaviour of highly soluble gases.