Predict Transport and Deposition of Multicomponent E-cigarette Aerosols in a Subject-specific Airway Model with Different Nicotine Forms: An in silico Study

Ted Sperry, Jianan Zhao, YU FENG, Chen Song, Zhiqiang Shi, Oklahoma State University

     Abstract Number: 12
     Working Group: Health-Related Aerosols

Abstract
Predicting the transport and deposition of e-cigarette aerosols in the human respiratory system is essential to understanding how initial e-liquid compositions, especially different nicotine forms in new generations of e-cigarette products, can influence the absorption of nicotine in the human lung. Using a newly developed computational fluid dynamics (CFD) based numerical method which integrated the species transport and discrete phase (DPM) models, this study simulated and compared the transport dynamics of multicomponent e-cigarette aerosols in a subject-specific human respiratory system, and investigated how nicotine forms, nicotine mass fraction, PG/VG ratio, and acid/nicotine ratio in the e-liquids can influence the transport, evaporation/condensation dynamics, and deposition/absorption patterns in the human airway from mouth to generation 6 (G6). Specifically, the experimentally calibrated and validated CFPD model is able to predict the gas-liquid phase change dynamics of water, PG, VG, and nicotine in the aerosols during their transport through the pulmonary route. Freebase nicotine and nicotine salt were both investigated, with different PG/VG ratios and benzoic or lactic acids. Simulation results indicate that compared with free-based nicotine e-liquid, using nicotine salt with Benzoic and Lactate Acids will reduce the headspace nicotine saturation pressure, thereby reducing the evaporation rate of nicotine, which leads to lower nicotine absorption in the human upper airway and higher nicotine absorption in small airways. In addition, increasing PG/VG ratio will also reduce the headspace nicotine saturation pressure, further reducing the evaporation rate of nicotine. In summary, a CFD-based species transport-DPM model has been developed and validated to quantify how e-liquid composition can influence the transport, evaporation/condensation, and deposition/absorption of inhaled multicomponent e-cigarette aerosol in human respiratory systems. Future work will include (1) investigating how disease-specific lung airway deformation kinematics can influence the inhaled nicotine distributions, and (2) quantifying the pharmacokinetics of nicotine after deposition/absorption in the human body.