Airway Caliber

The caliber of airways through which the aerosol has to pass to get to the more distal parts of the lungs is of utmost importance. In functional terms, the forced expiratory volume in one second, FEVi, is usually taken as a measure of the instantaneous resistance (and, hence, the caliber) of the airways. Therefore, it is customary to attempt to relate FEV1 to the deposition pattern. Using such functional tools, bronchoconstriction, or low values of FEVj, were shown to be associated with ahindrance of penetration of aerosols to the distal lungs [73,147152], and, conversely, bronchodilation enhanced the shift of deposition to the peripheral lungs [151]. This may have important therapeutic consequences. For example, it is known that the bronchodilatory potency can be increased by successive inhalation spaced by 10-min intervals to allow for bronchodilation. This was interpreted by the ability of the aerosol to reach receptors deeper in the lung by successive opening of the airways [153].

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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