Effects of supplemental oxygen on respiratory mechanics during exercise in healthy subjects breathing against an expiratory resistance
R. Duranti, P. Palange, S. Bertini, F. Gigliotti, R. Bianchi, G. Valli, R. Pellegrino, V. Brusasco, P. G. Agostoni, M. Guazzi, G. Scano (Florence, Rome, Cuneo, Genoa, Milan, Italy)
Source: Annual Congress 2002 - Lung mechanics: from laboratory to bedside
Session: Lung mechanics: from laboratory to bedside
Session type: Oral Presentation
Number: 189
Disease area: Airway diseases, Respiratory critical care
Abstract Aims. We investigated the effects of oxygen breathing on chest wall kinematics and respiratory muscle coordinated activity in exercising healthy subjects breathing against an expiratory resistance. Methods. We studied 7 healthy sedentary subjects (age 39±]7SD) at rest and during 6 min constant work rate exercise at 70% V'O2 peak on cycle ergometer while breathing from a Douglas bag in random order: room air (A), room air with an expiratory resistance (R), and 50% O2 with an expiratory resistance (RO). Chest wall (VTcw) and compartmental volumes (pulmonary apposed rib cage VTrc,p, diaphragm apposed rib cage VTrc,a and abdomen VTab) were measured by optoelectronic plethysmography. Esophageal and gastric pressures were measured by a standard catheter-balloon system. Results. Increase in VTcw was associated with increase in end-inspiratory and decrease in end-expiratory volumes. Compared to C, R caused an increase in tidal volume (VT) which was significantly reversed by RO. VTrc,p and VTrc,a but not VTab contributed to VTcw reduction. Peak pressure of rib cage inspiratory (Prcm,i) and expiratory (Prcm,e) muscles and of abdominal muscles (Pabm) increased significantly with R; oxygen was able to reduce significantly Prcm,i but neither Prcm,e nor Pabm. Conclusions. Exercise while breathing against an expiratory resistance is associated with increase in tidal volume and in Prcm,i, Prcm,e and Pabm. Supplemental oxygen is able to reduce VRC,p and VRC,a by decreasing the activity of rib cage inspiratory muscles.
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R. Duranti, P. Palange, S. Bertini, F. Gigliotti, R. Bianchi, G. Valli, R. Pellegrino, V. Brusasco, P. G. Agostoni, M. Guazzi, G. Scano (Florence, Rome, Cuneo, Genoa, Milan, Italy). Effects of supplemental oxygen on respiratory mechanics during exercise in healthy subjects breathing against an expiratory resistance. Eur Respir J 2002; 20: Suppl. 38, 189
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