Airway caliber has a dramatic influence on the pattern of deposition of aerosols in the airways. Deposition increases during bronchoconstriction, primarily as a result of changes in inertial impaction and turbulent flow experienced by aerosol particles after irregular airway obstruction [144]. The presence of excessive mucus may act to enhance further deposition [145]. Indeed, total lung aerosol deposition has been suggested as being a sensitive (perhaps diagnostic) indicator of airways obstruction or lung abnormality [146]. These processes may be envisaged as being advantageous insofar as they would function to deposit aerosolized drug at its site of desired action (i.e., the obstructed airway for a bronchodilator) but disadvantageous under circumstances in which the aerosol is to be delivered to the alveoli, because obstruction would result in a shift in the deposition pattern toward the central airways, that is, the sites of significant bronchoconstriction. In general, aerosolized drug will be deposited in regions of the pulmonary tree where airflow exists, and, accordingly, deposition in occluded airways probably will be diminished as a result of redirection of airflow through patent airways.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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