Measurements of Airway Dimensions and Calculation of Mass Transfer Characteristics of the Human Oral Passage

Cheng, Kuo-Hsi; Cheng, Yung‐Sung; Yeh, Hsu‐Chi; Swift, David L.

doi:10.1115/1.2798296

Cited by 92 publications

(75 citation statements)

References 14 publications

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“…Detailed airway dimensions in 0.3-cm intervals were reported. This Lovelace Respiratory Research Institute (LRRI) replica was used in the in vitro studies of nanoparticle deposition and coarse particle deposition of micro-metered sizes using standard test aerosols at constant inspiratory flow rates (20,50). The deposition efficiency for flow rates of 15, 30, and 60 L min −1 was plotted as a function of the impaction parameter (Fig.…”

Section: Deposition In the Oropharyngeal Regionsmentioning

confidence: 99%

See 1 more Smart Citation

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Cheng

2014

AAPS PharmSciTech

167

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Abstract. Aerosol delivery is noninvasive and is effective in much lower doses than required for oral administration. Currently, there are several types of therapeutic aerosol delivery systems, including the pressurized metered-dose inhaler, the dry powder inhaler, the medical nebulizer, the solution mist inhaler, and the nasal sprays. Both oral and nasal inhalation routes are used for the delivery of therapeutic aerosols. Following inhalation therapy, only a fraction of the dose reaches the expected target area. Knowledge of the amount of drug actually deposited is essential in designing the delivery system or devices to optimize the delivery efficiency to the targeted region of the respiratory tract. Aerosol deposition mechanisms in the human respiratory tract have been well studied. Prediction of pharmaceutical aerosol deposition using established lung deposition models has limited success primarily because they underestimated oropharyngeal deposition. Recent studies of oropharyngeal deposition of several drug delivery systems identify other factors associated with the delivery system that dominates the transport and deposition of the oropharyngeal region. Computational fluid dynamic simulation of the aerosol transport and deposition in the respiratory tract has provided important insight into these processes. Investigation of nasal spray deposition mechanisms is also discussed.

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Section: Deposition In the Oropharyngeal Regionsmentioning

confidence: 99%

“…An adult oral airway replica including an oral cavity and laryngeal and tracheal airway was casted from an alginate dental impression of a living Caucasian male adult; it represented approximately 50% of the full opening (50). Detailed airway dimensions in 0.3-cm intervals were reported.…”

Section: Deposition In the Oropharyngeal Regionsmentioning

confidence: 99%

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Cheng

2014

AAPS PharmSciTech

167

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“…2). This MT model was developed from the oral airway cast reported by Cheng et al (79) and in-house CT data of the pharynx and larynx. The inhaler was directly connected to the MT geometry assuming an insertion depth of 0.5 cm and an angle of zero degrees with the horizontal plane.…”

Section: Airway Modelsmentioning

confidence: 99%

Validating Whole-Airway CFD Predictions of DPI Aerosol Deposition at Multiple Flow Rates

Longest

Tian

Khajeh-Hosseini-Dalasm

et al. 2016

Journal of Aerosol Medicine and Pulmonary Drug Delivery

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Background: The objective of this study was to compare aerosol deposition predictions of a new whole-airway CFD model with available in vivo data for a dry powder inhaler (DPI) considered across multiple inhalation waveforms, which affect both the particle size distribution (PSD) and particle deposition. Methods: The Novolizer DPI with a budesonide formulation was selected based on the availability of 2D gamma scintigraphy data in humans for three different well-defined inhalation waveforms. Initial in vitro cascade impaction experiments were conducted at multiple constant (square-wave) particle sizing flow rates to characterize PSDs. The whole-airway CFD modeling approach implemented the experimentally determined PSDs at the point of aerosol formation in the inhaler. Complete characteristic airway geometries for an adult were evaluated through the lobar bronchi, followed by stochastic individual pathway (SIP) approximations through the tracheobronchial region and new acinar moving wall models of the alveolar region. Results: It was determined that the PSD used for each inhalation waveform should be based on a constant particle sizing flow rate equal to the average of the inhalation waveform's peak inspiratory flow rate (PIFR) and mean flow rate [i.e., AVG(PIFR, Mean)]. Using this technique, agreement with the in vivo data was acceptable with <15% relative differences averaged across the three regions considered for all inhalation waveforms. Defining a peripheral to central deposition ratio (P/C) based on alveolar and tracheobronchial compartments, respectively, large flow-rate-dependent differences were observed, which were not evident in the original 2D in vivo data. Conclusions: The agreement between the CFD predictions and in vivo data was dependent on accurate initial estimates of the PSD, emphasizing the need for a combination in vitro-in silico approach. Furthermore, use of the AVG(PIFR, Mean) value was identified as a potentially useful method for characterizing a DPI aerosol at a constant flow rate.

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“…Figure 1 shows the human airway cast used in the present study, including the oral cavity, pharynx, larynx, trachea, and four generations of bronchi. The oral portion of the cast was molded from a dental impression of an oral cavity of a human volunteer, while the other airway portions of the cast were made from a cadaver (Cheng et al 1997). The process of making the replica, and the dimension of the oral cavity and the particle deposition in this area were also investigated by Cheng et al (1999).…”

Section: Introductionmentioning

confidence: 99%

Particle Deposition in a Cast of Human Tracheobronchial Airways

Zhou

Cheng

2005

Aerosol Science and Technology

104

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Regional particle deposition efficiency and deposition patterns were studied experimentally in a human airway replica made from an adult cadaver. The replica includes the oral cavity, pharynx, larynx, trachea, and four generations of bronchi. This study reports deposition results in the tracheobronchial (TB) region. Nine different sizes of monodispersed, polystyrene latex fluorescent particles in the size range of 0.93-30 µm were delivered into the lung cast with the flow rates of 15, 30, and 60 l min −1 . Deposition in the TB region appeared to increase with the increasing flow rate and particle size. Comparison of deposition data obtained from physical casts showed agreement with results obtained from realistic airway replicas that included the larynx. Deposition data obtained from idealized airway models or replicas showed lower deposition efficiency. We also compared experimental data with theoretical models based on a simplified bend and bifurcation model. A deposition equation derived from these models was used in a lung dosimetry model for inhaled particles, and we demonstrated that there was general agreement with theoretical models. However, the agreement was not consistent over the large range of Stokes number. The deposition efficiency was found as a function of the Stokes number, bifurcation angle, and the diameters of parent and daughter tubes. An empirical model was developed for the particle deposition efficiency in the TB region based on the experimental data. This model, combined with the oral deposition model developed previously, can be used to predict the particle deposition for inertial effects with improved accuracy.

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Measurements of Airway Dimensions and Calculation of Mass Transfer Characteristics of the Human Oral Passage

Cited by 92 publications

References 14 publications

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Validating Whole-Airway CFD Predictions of DPI Aerosol Deposition at Multiple Flow Rates

Particle Deposition in a Cast of Human Tracheobronchial Airways

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