Factors affecting distribution of airflow in a human tracheobronchial cast.
Air velocity was measured at end airways of hollow replicate casts of the human tracheobronchial tree in order to determine the flow distribution within casts extending to 3 mm diameter airways. Measurements were made by hot-wire anemometry for constant inspiratory flow rates of 7.5, 15, 30 and 60 L.min-1. Average flow distribution among the lung lobes was as follows: right upper, 18.5%; right middle, 9.2%; right lower, 32.3%; left upper, 15.7%; and left lower, 24.3%. An empirical model derived from the experimental flow distribution data demonstrated the effect of various morphometric parameters of the hollow cast on the distribution of airflow. Airway cross-sectional area, branching angle and total path-length were found to have the greatest influence. As the tracheal flow rate decreased from 60 to 7.5 L.min-1, the influence of branching angle was reduced, while total path-length became more influential. These results provide evidence for the transition of flow regimes within the TB tree within normal physiological flow ranges.
Cohen
B S
BS
Institute of Environmental Medicine, New York University Medical Center, New York.
Sussman
R G
RG
Lippmann
M
M
D000328:Adult; D001980:Bronchi / Q000502:physiology*; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D008954:Models, Biological; D012123:Pulmonary Ventilation / Q000502:physiology*; D014132:Trachea / Q000502:physiology*