[Pulmonary function differences in healthy subjects according to postural changes (author's transl)].
The total lung capacity (TLC) and its subdivisions along with the forced spirometric values (FEF25-75 and FEV1) were determined in a group of 44 healthy subjects, composed of 29 women and 15 men. The determinations were carried out in a sitting position and in supine position, breathing air. All the pulmonary volumes diminished when the subject lay down, but the functional residual capacity (FRC) was that which underwent a greater reduction. The residual volume decrease was the only one which did not reach statistically significant levels. Women always showed smaller pulmonary volumes than men. It has been demonstrated that FRC can be exactly measured by means of the closed helium technique. The regression figures of FRC in supine position were determinted for both sexes, with a r = 0,33 (p less than 0,1) in women and r = 0,95 (p less than 0.001) in men. The forced spirometric tests did not undergo any important changes although the reduction of the FEV1 was significant in both sexes. The results obtained were compared with those published by other authors.