Inhalation airflow and ventilation efficiency in subject-specific human upper airways

https://doi.org/10.1016/j.resp.2020.103587Get rights and content
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Highlights

  • The transportation time of the inhaled chemical in airway model was investigated.

  • Two indexes were introduced to quantify the ventilation efficiency in upper airway.

  • The variation of the ventilation efficiency with the flow rate was discussed.

  • The long regional staying time of inhaled chemical suggests the high potential of the surface adsorption.

  • The transportation time could aid in assessing the potential impact of the inhaled chemicals on human health.

Abstract

The present numerical study investigated the transportation time of the inhaled chemicals in three realistic human airway models by adopting a methodology from the field of the building ventilation. Two indexes including “scale of ventilation efficiency 3 (SVE3)” and “local purging flow rate (L-PFR)” were used to evaluate the respective arrival time and staying time under different inhalation flow rates. The general trend of the SVE3 was predicted as expected and the exceptions within the nasal cavities were attributed to the uneven allocation of the inhaled flow between the internal channels and the formation of the vortex circulation therein. The complicated situation of the L-PFR was also explained by the structure constrains. Moreover, the variation of the two indexes with the flow rate was sensitive to the inter-subjective differences but the distribution pattern was not changed significantly. By combining the SVE3 and L-PFR, it could help with assessing the potential effect of the inhaled chemicals on the human health for engineering applications to which the relative impacts are more interested than the absolute value. But for the precise evaluation regarding a specific chemical, comprehensive simulation is still necessary with the surface adsorption included under realistic respiration cycles.

Keywords

Human upper airway
Ventilation efficiency
Local purging flow rate
Transportation time
Inhaled chemical

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