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Lung deposition of inhaled particles depending on respiratory profile

Impaction of particles is dependent on size and velocity of flow. While slowly inhaled particles may follow the inspiratory flow unhindered through narrowings and curves faster travelling particles deposit already in the upper respiratory tract. Particles smaller then 2 to 3 µm are not affected by impaction and reach peripheral airways even more effectively during slow inhalation (< 30 l/min).

Regarding sedimentation the inspiratory flow rate does not play a crucial role. However protracted flow expands the time in which the amount of aerosol taken with one breath stays in the respiratory tract, thus leading to a higher rate of deposition by sedimentation.

Following permanent aerosol generation the applied dose increases the deeper the breath. Since the volume of functional dead space in the respiratory tract averages about 150-300 ml particles only reach more distal parts of the lung with an inspiratory volume of more than 300 ml. Additionally the duration of a breath increases with its volume also leading to a higher lung deposition.


Voshaar T. Therapie mit Aerosolen. 2005. Uni-Med: Bremen

Deposition of particles depending on size, inspiratory volume, and air flow

In this interactive tool sliders can be moved to choose a certain inspiratory flow rate, inspiratory volume or particle size. Colouring of the respiratory tract indicating the amount of inhaled aerosol reaching certain regions will change according to the chosen values. Additionally, clicking on the buttons “extra-thoracic?, “bronchial? or “alveolar? will shift the sliders to values, which most likely lead to aerosol deposition in the chosen region.

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