REDISTRIBUTION OF PULMONARY VENTILATION DURING HIGH-FREQUENCY VENTILATION (HFV).

Local parenchymal volume changes were measured in intact dogs during high-frequency ventilation (HFV) by tracking the motion of implanted 1-mm stainless steel markers with high-speed biplane cineradiography. Marker 3-D coordinates were recovered by computer analysis of the films with an accuracy of 0. 15 mm. Oscillatory volume changes (mean, amplitude, and phase) of tetrahedral elements consisting of groups of four markers were analyzed as functions of frequency, tidal volume, and mean airway pressure. This information was used to determine the intra- and interlobar distribution of oscillatory volume changes. The results, which show that there are significant temporal and spatial nonuniformities of ventilation during HFV, are consistent with the importance of gas inertia and interrregional airflow.