Measurement of the separate volume changes of rib cage and abdomen during breathing.

KONNO, KIMIO, AND JERE MEAD. Measurement of the separate volume changes of rib cage and abdomen during breathing. J. Appl. Physiol. 22(3) : 407-422. I 967 .-Changes in the anteroposterior diameters of the rib cage and abdomen were recorded on the axes of a direct-writing X-Y recorder both during relaxation against a closed airway at different lung volumes, and while, at fixed lung volumes, displacements of volume were made voluntarily back and forth between the rib cage and abdomen in both the standing and supine postures. The family of isovolume lines was used to construct the volume-motion relationships for the rib cage and abdomen, and this in turn was used to estimate the separate volume changes of these parts during breathing. A high degree of volume dependence between the rib cage and abdomen was demonstrated under isovolume conditions, while a high degree of volume independence between these parts was demonstrated when total volume change was unconstrained. During breathing the chest wall deviated substantially from its passive configuration. In six subjects the abdomen accounted for about half or more of the tidal volume, but much less than half of the vital capacity, in both postures.