Abstract
To compare the static hysteresis of lungs with that of the airways, dead space volumes were measured at the same lung volumes immediately after inspiring to maximum lung volumes and immediately after expiring to minimum lung volumes. Dead space volumes, measured with the Fowler technique and with CO2 as the test gas, were slightly but significantly greater (average 8%) after inspiring to maximum lung volumes. The hysteresis of the dead space of normal subjects at relatively high lung volumes (58-83% VC, where VC = vital capacity) is slightly greater than that of the lung.