Enhancement of particle deposition by flow-limiting segments in humans

hancement of particle deposition by flow-limiting segments in humans. J. Appl. Physiol. 59(2): 509-514, 1985.-Severe during a quiet inspiration and rapid but passive expira-chronic obstructive pulmonary disease is associated with cen-tion without significant deposition (14). When expiration tral deposition of inhaled aerosols. This pattern may be due to was forced, there was a significant increase in deposition functional narrowing of the large airways during expiration at just downstream to the tracheal site of flow limitation. flow-limiting segments (FLS). Using a gamma camera and 2.5-This study suggested that FLS impart sufficient inertia pm particles, we compared the pattern of aerosol deposition to small particles to cause local impaction to dominate following quiet breathing with that after a controlled forced over clearance mechanisms and result in net deposition. expiration (cough) when FLS are known to form in central We found that the pattern of deposition in the dog was airways. Lung size measurement by 133Xe allowed construction similar to particle deposition in tubes containing a nar