Journal of applied physiology
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Two healthy males relaxing supine on a ballistobed were mechanically ventilated at positive end-expiratory pressures (PEEP) from 0 to 19 cmH2O. Pressures at the airway opening, middle esophagus, and stomach were monitored, together with tidal volume (VT) and ballistobed displacement. ⋯ The combined effective elastance of abdomen and diaphragm (E'ab+di) first decreased and then increased again. The abdomen-diaphragm contribution to VT during mechanical ventilation was approximately half that of spontaneous breathing.
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By use of the method of Konno and Mead and the respiratory magnetometer, the partition of respired gas volumes into rib cage and diaphragm-abdomen components was accomplished in 81 normal subjects including 32 young and middle-aged men, 29 young and middle-aged women, and 20 elderly men. Studied were isovolume maneuvers and the relaxation configuration over the inspiratory capacity range, quiet tidal breathing, increased amplitudes of slow breathing, rapid inspirations and expirations, and both quiet and forceful phonation. ⋯ Rapid respiratory maneuvers were accomplished mostly through rib cage displacement suggesting that rib cage muscles are capable of more rapid action than diaphragm and abdominal muscles. Data from deep breathing and rapid maneuvers supported the view that abdominal and rib cage muscles often act to optimize the mechanical (length-tension) advantage of the diaphragm.