Deposition of Ultrafine Aerosols in the Head Airways During Natural Breathing and During Simulated Breath Holding Using Replicate Human Upper Airway Casts

Abstract

Natural breathing and simulated breath-holding techniques have been used to measure inspiratory and expiratory head deposition of inhaled particles in human subjects. Because the simulated breath-holding path, in which the aerosol is drawn through the nose and mouth, differs from the natural path where inhaled particles enter the nose and penetrate through the larynx and trachea, the present study was undertaken to compare the deposition of ultrafine aerosol between these two experimental methods. Two replicate human upper airway casts containing a nasal airway, an oral passage, and a laryngeal-tracheal section were used to measure the head deposition efficiencies of monodisperse silver or polystyrene latex particles. Particles whose thermodynamic diameters ranged from 3.6 to 150 nm were drawn through the casts a t constant flow rates ranging from 4 to 30 L/min. For the inhalation study, test aerosols were drawn into the nasal airway and directed either through the laryngealtracheal section or through the oral passage; these flow patterns were reversed for the exhalation study. Results indicated that the difference in ultrafine aerosol deposition was not statistically significant at the 95% confidence level between the nose-mouth and nosetrachea paths for inhalation ( p = 0.10) and exhalation ( p = 0.33). For the range of particle sizes and flow rates studied, this finding suggests that the simulated breath-holding method, where test aerosols are drawn through the nose and mouth, is appropriate for estimating the inspiratory and expiratory deposition efficiency of ultrafine particles in the nose-trachea path.

Subject-variability effects on micron particle deposition in human nasal cavities

“…Other studies, using methods like acoustic⧹optical rhinometry and rhinomanometry as well as MRI and CT techniques, have shown large variations in nasal cross-sectional area and nasal resistance (Corey, Gungor, Liu, Nelson, & Fredberg, 1998;Corey, Gungor, Nelson, Fredberg, & Lai, 1997;Menache et al, 1997). Preliminary results from in vivo and in vitro methods have confirmed the individual differences in nasal anatomy which leads to intersubject variability in aerosol deposition (Bennett & Zeman, 2005;K.-H. Cheng et al, 1996;Cheng et al, 1991Cheng et al, , 1995Y. S. Cheng et al, 1996;Cheng, 2003;Garcia, Tewksbury, et al, 2009;Kesavan et al, 2000;Kesavanathan & Swift, 1998;Kesavanathan, Bascom et al, 1998;Rasmussen et al, 2000;Wiesmiller et al, 2003).…”

Numerical optimization of targeted delivery of charged nanoparticles to the ostiomeatal complex for treatment of rhinosinusitis

“…This dataset was initially implemented in 1989 by Guilmette et al to prepare in vitro casts and has been used in multiple simulations and experiments of particle depositions. [33][34][35][36][37] Image-segmentation software MIMICS (Materialise, Ann Arbor, MI, USA) was used to convert the MRI scans into contours defining the nasal cavity and the maxillary sinus. A surface geometry was constructed from these contours in Gambit.…”

Improving the Lung Delivery of Nasally Administered Aerosols During Noninvasive Ventilation—An Application of Enhanced Condensational Growth (ECG)

“…The nasal geometry was based on the MRI data set originally reported in the study of Guilmette (43) for an adult male and subsequently used in a number of in vitro experiments (29,(44)(45)(46) and CFD simulations. (41,47,48) The surface area to volume ratio of this model is approximately 1, which is consistent with population mean values for healthy adults.…”