Single-breath washouts in a rotating stretcher.
Rodríguez-Nieto, M. J., G. Peces-Barba, N. González Mangado, S. Verbanck, and M.
Paiva.
1Laboratorio de Fisiopatología Respiratoria, Fundación Jiménez Díaz, Madrid, Spain;
2Respiratory Division, Academic Hospital, Vrije Universiteit Brussel, 1090 Brussels; and
3Laboratoire de Physique Biomédicale, Université Libre de Bruxelles, 1070 Brussels,
Belgium
APStracts 7:0050A, 2000.
Vital capacity single-breath washouts using 90% O2-5% He-5% SF6 as a test gas mixture
were performed with subjects sitting on a stool (upright) or recumbent on a stretcher
(prone, supine, lateral left, lateral right, with or without rotation at end of inhalation). On
the basis of the combinations of supine and prone maneuvers, gravity-dependent
contributions to N2 phase III slope and N2 phase IV height in the supine posture were
estimated at 14% and 68%, respectively. Whereas both He and SF6 slope decreased from
supine to prone, the SF6-He slope difference actually increased (P = 0.015). N2 phase III
slopes, phase IV heights, and cardiogenic oscillations were smallest in the prone posture,
and we observed similarities between the modifications of He and SF6 slopes from
upright to prone and from upright to short-term microgravity. These results suggest that
phase III slope is partially due to emptying patterns of small units with different
ventilation-to-volume ratios, corresponding to acini or groups of acini. Of all body
postures under study, the prone position most reduces the inhomogeneities of ventilation
during a vital capacity maneuver at both inter- and intraregional levels.
Received 9 April 1999; accepted in final form 20 October 2000
APS Manuscript Number A0285-9.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2000 The American Physiological Society.
Published in APStracts on 29 January 2001