Airway closure: demonstration by breathing 100 percent O2 at low lung volumes and by N2 washout.

Publisher Website
Google Scholar
Abstract
Seven normal subjects breathed 100% O2 at low lung volumes for 2 min. following a period of denitrogenation by O, breathing, Quasi-static pressure-volume curves were measured in these subjects during the initial and subsequent inflations from residual volume immediately following the experimental procedure. Comparisons were made with control experiments in which the inhaled gas was air. In 8 out of 10 trials on O2, the initial, postexposure inflation curves were shifted (relative to the air control curves) in the direction of increased pressure for the same volume, and these deep breaths were accompanied by symptoms of chest pain and/or cough. In 1 series where the procedure was altered to change, the inhaled gas abruptly from O2 to air just as the subjects began to breathe at low lung volumes, the results resembled those obtained after breathing O2 throughout. Alternatively, if the inhaled gas were changed from air to O2 the results corresponded to those obtained after breathing air throughout. These results are indicative of airway closure at low lung volumes with subsequent atelectasis if N2 was absent from the alveolar gas. Additional measurements of N2 evolved from tranned air confirmed this view. Most airway closure occurred below 20% of vital capacity. Apparent opening pressures during inflation suggested that the collapsed airways were relatively large ([image] 0.9 mm id).

This publication has 3 references indexed in Scilit: