You are here:
Empirical model for conveniently predicting total and regional lung deposition of inhaled aerosols
Citation:
Kim, C. AND S. Hu. Empirical model for conveniently predicting total and regional lung deposition of inhaled aerosols. International Society for Aerosols in Medicine, Santa Fe, NM, June 03 - 07, 2017.
Impact/Purpose:
Accurate estimate of a dose of inhaled aerosols is a key factor for estimating potential health risks to exposure to ambient pollutant particulate matter on the one hand, and the therapeutic efficacy of inhaled drug aerosols on the other hand. Particle deposition in the lung is determined primarily by particle size and breathing pattern (tidal volume, breathing frequency and flow rate) besides lung morphology. In the past, lung deposition data were analyzed without a full consideration of breathing pattern and as a result, empirical relationships were subject to a large uncertainty. Thus, it is important to analyze the data considering all relevant parameters affecting lung deposition so that predictive results may be correctly related to realistic inhalation exposure conditions. We have developed a set of four empirical equations for predicting both total and regional lung deposition dose of inhaled particles in healthy adult subjects for a wide range of inhalation conditions. This allows risk assessors and health scientists to conveniently estimate lung doses under various exposure conditions without using mathematical models.
Description:
Accurate estimate of a dose of inhaled aerosols is a key factor for estimating potential health risks to exposure to ambient pollutant particulate matter on the one hand, and the therapeutic efficacy of inhaled drug aerosols on the other hand. Particle deposition in the lung is determined primarily by particle size and breathing pattern (tidal volume, breathing frequency and flow rate) besides lung morphology. In the past, lung deposition data were analyzed without a full consideration of breathing pattern and as a result, empirical relationships were subject to a large uncertainty. In the present study we compiled and analyzed experimental data for both ultrafine and micron sized particles in normal adults and derived empirical equations for total and regional deposition as a function of both particle size and breathing patterns. Deposition was expressed by combination of two composite parameters; X1= (DTm)^pVt^q for ultrafine particles and X2= dp^mQ^nVt^s for micron particles. Here, D is diffusion coefficient, Tm is mean respiratory time, Vt is tidal volume, dp is particle diameter, Q is mean respiratory flow rate. We found that total deposition fraction (TDF) can be expressed by a single function in the form of TDF = 1-1/(1+aX1 + bX2). Extrathoracic (ET) and tracheobronchial (TB) deposition can also be expressed with similar functions. Alveolar deposition (AL) then is obtained by AL = TDF-(ET+TB). Therefore, both total and regional deposition values can be estimated for a wide range of inhalation conditions using four simple empirical equations. Results were very close to comprehensive mathematical models, making the present empirical model particularly useful in case that valid mathematical models are not available or inaccessible.