Abstract
A considerable degree of pulmonary collapse can be maintained in man with very little alteration of respiratory function other than an abnormal amount of hyperventilation on exertion. Latent physiological abnormalities usually become manifest clinically only under stress. The response to exercise is too dependent upon physical fitness to be a reliable guide to the capacity of an individual to compensate for a reduction of lung volume. Since oxygen lack constitutes the greatest danger to patients who have disorders of respiration, the oxygen saturation of the arterial blood while breathing a mixture of gases containing less oxygen than the atmosphere would seem to furnish a simple and quantitative test of one phase of respiratory efficiency while the subject remains at rest.
The procedure consists in the analysis of the alveolar air and arterial blood while the subject breathes room air and again while he breathes from a Douglas bag containing about 16% oxygen in nitrogen. By this means it is possible to ascertain the degree of arterial saturation produced by the observed alveolar oxygen tension. Alveolar air was withdrawn in 1 or 2 cc portions from the axial stream in the center of the mouthpiece of a set of respiration valves at the end of successive expirations until 40 cc or more were obtained. This is essentially a modification of the method of Krogh and Lindhard 1 which was shown by Debenham and Poulton 2 to give results which agree with Haldane-Priestley samples. Air analyses were done in the Haldane-Henderson apparatus.
Arterial puncture is often painful and frequently causes patients to hold their breath or hyperventilate, and full reliance cannot always be placed upon the analysis of blood obtained by this means. 3 Since 2 samples of blood are taken within a few minutes of each other in this procedure, the method of Goldschmidt and Light 3 was used.
Get full access to this article
View all access options for this article.