Computational Models for Simulating Multicomponent Aerosol Evaporation in the Upper Respiratory Airways

Longest, P. Worth; Kleinstreuer, Clement

doi:10.1080/027868290908786

Cited by 54 publications

(49 citation statements)

References 45 publications

(58 reference statements)

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“…Application of the RMM approach to inhaled respiratory aerosols was previously validated by Longest and Kleinstreuer. (58) The droplet heat and mass transfer relations are described in detail by Longest and Hindle. (32) In simulating aerosol evaporation and growth, the effect of the droplets on the continuous phase was typically neglected, resulting in a one-way coupled approach.…”

Section: Cfd Simulationsmentioning

confidence: 99%

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

Longest

Tian²,

Hindle³

2011

Journal of Aerosol Medicine and Pulmonary Drug Delivery

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Background: Aerosol drug delivery during noninvasive ventilation (NIV) is known to be inefficient due to high depositional losses. To improve drug delivery efficiency, the concept of enhanced condensational growth (ECG) was recently proposed in which a submicrometer or nanoaerosol reduces extrathoracic deposition and subsequent droplet size increase promotes lung retention. The objective of this study was to provide proof-of-concept that the ECG approach could improve lung delivery of nasally administered aerosols under conditions consistent with NIV. Methods: Aerosol deposition and size increase were evaluated in an adult nose-mouth-throat (NMT) replica geometry using both in vitro experiments and CFD simulations. For the ECG delivery approach, separate streams of a submicrometer aerosol and warm (398C) saturated air were generated and delivered to the right and left nostril inlets, respectively. A control case was also considered in which an aerosol with a mass median aerodynamic diameter (MMAD) of 4.67 mm was delivered to the model. Results: In vitro experiments showed that the ECG approach significantly reduced the drug deposition fraction in the NMT geometry compared with the control case [14.8 (1.83)%-ECG vs. 72.6 (3.7)%-control]. Aerosol size increased from an initial MMAD of 900 nm to a size of approximately 2 mm at the exit of the NMT geometry.Results of the CFD model were generally in good agreement with the experimental findings. Based on CFD predictions, increasing the delivery temperature of the aerosol stream from 21 to 358C under ECG conditions further reduced the total NMT drug deposition to 5% and maintained aerosol growth by ECG to approximately 2 mm. Conclusions: Application of the ECG approach may significantly improve the delivery of pharmaceutical aerosols during NIV and may open the door for using the nasal route to routinely deliver pulmonary medications.

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Section: Cfd Simulationsmentioning

confidence: 99%

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

Longest

Tian²,

Hindle³

2011

Journal of Aerosol Medicine and Pulmonary Drug Delivery

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“…This expression includes the effect of droplet evaporation on the evaporation rate, which is referred to as the blowing velocity (Longest and Kleinstreuer 2005). In Equation (18), C M is the mass Knudsen number correction, which is equivalent to Equation (17) with a mass-based accom-…”

Section: Droplet Evaporation and Condensation Modelmentioning

confidence: 99%

“…The evaporation and condensation model employed for CSPs is based on previous approximations for salts (Ferron 1977;Ferron et al 1988;Hinds 1999), CSPs (Li and Hopke 1993;Robinson and Yu 1998), and multicomponent evaporating liquid droplets in the respiratory tract (Longest and Kleinstreuer 2005). In this model, CSPs are assumed to consist of liquid water, water soluble components, and non-soluble components.…”

Section: Droplet Evaporation and Condensation Modelmentioning

confidence: 99%

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Condensational Growth May Contribute to the Enhanced Deposition of Cigarette Smoke Particles in the Upper Respiratory Tract

Longest

2008

Aerosol Science and Technology

113

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Previous experimental studies have shown that concentrated cigarette smoke particles (CSPs) deposit in the upper airways like much larger 6 to 7 µm aerosols. Based on the frequent assumption that relative humidity (RH) in the lungs does not exceed approximately 99.5%, the hygroscopic growth of initially submicrometer CSPs is expected to be a relatively minor factor. However, the inhalation of mainstream smoke may result in humidity values ranging from sub-saturated through supersaturated conditions. The objective of this study is to evaluate the effect of condensation particle growth on the transport and deposition of CSPs in the upper respiratory tract under various RH and temperature conditions. To achieve this objective, a computational model of transport in the continuous phase surrounding a CSP was developed for a multicomponent aerosol consisting of water soluble and insoluble species. To evaluate the transport and deposition of dilute hygroscopic CSPs in the upper airways, a model of the human mouththroat (MT) through approximately respiratory generation G6 was considered with four steady inhalation conditions. These inhalation conditions were representative of inhaled ambient cigarette smoke as well as warm and hot saturated smoke. Results indicate that RH conditions above 100% are possible in the upper respiratory tract during the inhalation of a warm or hot saturated airstream. For sub-saturated inhalation conditions, initial evaporation of the CSPs was observed followed by hygroscopic growth and diameter increases less than approximately 50%. In contrast, the inhalation of warm or hot saturated air resulted in significant particle growth in the MT and tracheobronchial regions. For the inhalation of warm saturated air 3• C above body temperature, initially 200 and 400 nm particles were observed to increase in size to above 3 µm near the trachea inlet. The upper boundary inhalation condition • C air resulted in 7 to 8 µm droplets entering the trachea. These results do not prove that the enhanced deposition of CSPs in the upper airways is only a result of condensational growth. However, this study does highlight condensational growth as a potentially significant mechanism in the deposition of smoke particles under saturated inhalation conditions. INTRODUCTIONRelationships between cigarette smoke constituents and lung disease, respiratory and systemic cancer, and cardiovascular disease have been well established (Doll and Hill 1950;Wynder and Graham 1950; WHO 2002; U.S. Department of Health and Human Services 2004;. Considering bronchogenic carcinoma, a number of studies have reported evidence linking local sites of deposited cigarette smoke particles (CSPs) with disease formation (Bryson and Spencer 1951;Ermala and Holsti 1955;Martonen 1986;Martonen et al. 1987;Yang et al. 1989). For example, Yang et al. (1989) reported significantly elevated incidents of bronchogenic carcinoma at sites that coincided with previously observed CSP deposition from other studies (Bryson and Spencer 1951;Ermala and Holsti 1...

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“…A number of experimental and modeling studies of the behavior of free aerosols have been conducted (Zhang et al 1987a;Lehtinen et al 1998;Longest et al 2005;Hopkins et al 2006;Debry et al 2007;Lim et al 2008). The complexity of the phenomena involved in the evaporation of collected aerosols, however, in particular those relating to the interactions between drops and fibers, accounts for the lack of experimental and theoretical studies in this field.…”

Section: Introductionmentioning

confidence: 99%

Evaporation of Liquid Semi-Volatile Aerosols Collected on Fibrous Filters

Sutter¹,

Bémer²,

Appert-Collin

et al. 2010

Aerosol Science and Technology

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Numerous sources of liquid aerosols are to be found in industrial environments. Such aerosols may, for instance, be cutting fluids, pesticides, etc., that are harmful or even toxic to humans. To control and reduce worker exposure to potentially toxic aerosols, these latter are usually filtered through fibrous filters. When nonsaturated air traverses a clogged filter, however, the drops deposited on the fibers may evaporate. Consequently, workers are exposed to greater amounts of more concentrated vapors than the initial state of the filtered aerosol. Furthermore, exposure readings are distorted by an artifact that may be significant. This study offers an experimental approach to long-term monitoring of the evaporation of a semi-volatile n-hexadecane liquid aerosol deposited on filters of varying efficiency. Results were modeled using two semiempirical models for identifying the basic parameters of liquid aerosol evaporation on fibers. For the first time ever it has been demonstrated that the Fick's first law, as previously suggested by models proposed in the literature, does not control evaporation kinetic.

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Computational Models for Simulating Multicomponent Aerosol Evaporation in the Upper Respiratory Airways

Cited by 54 publications

References 45 publications

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

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

Condensational Growth May Contribute to the Enhanced Deposition of Cigarette Smoke Particles in the Upper Respiratory Tract

Evaporation of Liquid Semi-Volatile Aerosols Collected on Fibrous Filters

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