Relative volume changes between lobes of the lung

¹ Firland Sanatorium and Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington

Lobarspirometry was used to measure the relative volume changes between pulmonary lobes in normal human subjects. The flow resistive properties of the system were obviated by having the subject interrupt flow throughout the vital capacity range. The plot of relative volume changes of the upper and the lower lobe during inspiration was curvilinear in all subjects. Expiration had a less consistent pattern, but most often the upper lobe, rather than the lower lobe, contributed more to late expiration. The plot of volume differences between lungs did not reveal a consistent relationship. However, in contrast to the plot of the lobes, the plot of the lung volumes was often linear. The breath-holding points frequently showed a ‘creep’ phenomenon where the volume changes between lobes were opposite in direction or where the volume in one lobe remained constant, while that in the other was increasing or decreasing. Changes in body position did not affect these curves. The occurrence of unequal volume changes must mean that the mechanical properties of the units differ or that they are exposed to different stresses.