Single-breath washouts in a rotating stretcher

• Published in: Journal of applied physiology (1985) 2001-04, Vol.90 (4), p.1415-1423
• Main Authors: Rodriguez-Nieto, M. J, Peces-Barba, G, Mangado, N. Gonzalez, Verbanck, S, Paiva, M
• Format: Article
• Language: English
• Subjects: Adult; Air breathing; Biological and medical sciences; Female; Fundamental and applied biological sciences. Psychology; Hemodynamics - physiology; Humans; Inspiratory Capacity - physiology; Male; Middle Aged; Nitrogen - metabolism; Posture; Posture - physiology; Prone Position - physiology; Pulmonary Gas Exchange - physiology; Respiratory Function Tests - instrumentation; Respiratory Mechanics - physiology; Respiratory system; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Rotation; Space life sciences; Supine Position - physiology; Vertebrates: respiratory system; Vital Capacity - physiology
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2001.90.4.1415

1  Laboratorio de Fisiopatología Respiratoria, Fundación Jiménez Díaz, Madrid, Spain; 2  Respiratory Division, Academic Hospital, Vrije Universiteit Brussel, 1090 Brussels; and 3  Laboratoire de Physique Biomédicale, Université Libre de Bruxelles, 1070 Brussels, Belgium Vital capacity single-breath washouts using 90% O 2 -5% He-5% SF 6 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 N 2 phase III slope and N 2 phase IV height in the supine posture were estimated at 18% and 68%, respectively. Whereas both He and SF 6 slope decreased from supine to prone, the SF 6 -He slope difference actually increased ( P  = 0.015). N 2 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 SF 6 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. ventilation inhomogeneity; posture; phase III slope; phase IV height; cardiogenic oscillations