1
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Guo Y, Tang Y, Su Y, Sun D. Influencing factors of particle deposition in the human nasal cavity. Laryngoscope Investig Otolaryngol 2024; 9:e1308. [PMID: 39040121 PMCID: PMC11261810 DOI: 10.1002/lio2.1308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 07/03/2024] [Accepted: 07/12/2024] [Indexed: 07/24/2024] Open
Abstract
Objective To review the existing literature on the application of computational fluid dynamics methods to study nasal particle deposition and to summarize and analyze the factors affecting nasal particle deposition in order to provide theoretical references for the development of future transnasal drug delivery devices and the prevention of respiratory-related diseases. Data Source PubMed and CNKI databases. Methods A search of all current literature (up to and including February 2023) was conducted. Search terms related to the topic of factors influencing nasal particle deposition were identified, and queries were conducted to identify relevant articles. Results Both the properties of the particles themselves and the environmental conditions external to the particles can affect particle deposition in the nasal cavity, with particle deposition showing a positive correlation with particle size, particle density, and airflow velocity, with increasing subject age leading to a decrease in deposition, and with the relationship between airflow temperature and humidity still requiring more research to further explore. Conclusions With the popularity of computational fluid dynamics, more and more scholars have applied computational fluid dynamics technology to explore the influence of different parameters on particle deposition. By summarizing and analyzing the influence law of various factors on deposition, it can provide a theoretical basis for the future development and application of transnasal drug delivery devices and the prevention of respiratory-related diseases, which makes a significant contribution to the optimization of clinical disease prevention and treatment. Level of Evidence NA.
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Affiliation(s)
- Yingke Guo
- Department of Otolaryngology Head and Neck SurgerySecond Affiliated Hospital of Dalian Medical UniversityDalianLiaoning ProvinceChina
| | - Yuanyuan Tang
- Department of Otolaryngology Head and Neck SurgerySecond Affiliated Hospital of Dalian Medical UniversityDalianLiaoning ProvinceChina
| | - Yingfeng Su
- Department of Otolaryngology Head and Neck SurgerySecond Affiliated Hospital of Dalian Medical UniversityDalianLiaoning ProvinceChina
| | - Dong Sun
- Department of Otolaryngology Head and Neck SurgerySecond Affiliated Hospital of Dalian Medical UniversityDalianLiaoning ProvinceChina
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2
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Mao N, Zhang D, Li Y, Li Y, Li J, Zhao L, Wang Q, Cheng Z, Zhang Y, Long E. How do temperature, humidity, and air saturation state affect the COVID-19 transmission risk? ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:3644-3658. [PMID: 35951241 PMCID: PMC9366825 DOI: 10.1007/s11356-022-21766-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/27/2022] [Indexed: 05/10/2023]
Abstract
Environmental parameters have a significant impact on the spread of respiratory viral diseases (temperature (T), relative humidity (RH), and air saturation state). T and RH are strongly correlated with viral inactivation in the air, whereas supersaturated air can promote droplet deposition in the respiratory tract. This study introduces a new concept, the dynamic virus deposition ratio (α), that reflects the dynamic changes in viral inactivation and droplet deposition under varying ambient environments. A non-steady-state-modified Wells-Riley model is established to predict the infection risk of shared air space and highlight the high-risk environmental conditions. Findings reveal that a rise in T would significantly reduce the transmission of COVID-19 in the cold season, while the effect is not significant in the hot season. The infection risk under low-T and high-RH conditions, such as the frozen seafood market, is substantially underestimated, which should be taken seriously. The study encourages selected containment measures against high-risk environmental conditions and cross-discipline management in the public health crisis based on meteorology, government, and medical research.
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Affiliation(s)
- Ning Mao
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute of Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Dingkun Zhang
- Laboratory of Clinical Proteomics and Metabolomics, Institutes for Systems Genetics, West China Hospital, Sichuan University, Chengdu, China
| | - Yupei Li
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute of Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Ying Li
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Jin Li
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Li Zhao
- China Academy of Building Research, Beijing, China
| | - Qingqin Wang
- China Academy of Building Research, Beijing, China
| | - Zhu Cheng
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Yin Zhang
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Enshen Long
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute of Disaster Management and Reconstruction, Sichuan University, Chengdu, China
- College of Architecture and Environment, Sichuan University, Chengdu, China
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3
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Septoplasty Effect on the Enhancement of Airflow Distribution and Particle Deposition in Nasal Cavity: A Numerical Study. Healthcare (Basel) 2022; 10:healthcare10091702. [PMID: 36141314 PMCID: PMC9498368 DOI: 10.3390/healthcare10091702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022] Open
Abstract
The surgery outcomes after fixing nasal airway obstruction (NAO) are sometimes not satisfactory in improving ventilations of airflow. A case study is presented in this paper with computational fluid dynamics applied to determine the key factors for successful septoplasty plans for a patient with a deviated nasal septum. Specifically, airflow, as well as particle transport and deposition were predicted in a pre-surgery nasal cavity model reconstructed from patient-specific Computer Tomography (CT) images and two post-surgery nasal cavity models (i.e., VS1 and VS2) with different virtual surgery plans A and B. Plan A corrected the deviated septal cartilage, the perpendicular plate of the ethmoid bone, vomer, and nasal crest of the maxilla. Plan B further corrected the obstruction in the nasal vestibule and caudal nasal septal deviation based on Plan A. Simulations were performed in the three nose-to-throat airway models to compare the airflow velocity distributions and local particle depositions. Numerical results indicate that the VS2 model has a better improvement in airflow allocation between the two sides than the VS1 model. In addition, the deposition fractions in the VS2 model are lower than that in both the original and VS1 models, up to 25.32%. The better surgical plan (i.e., Plan B) reduces the particle deposition on the convex side, but slightly increases the deposition on the concave side. However, the overall deposition in the nasal cavity is reduced.
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4
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Chen IL, Chen HL. New developments in neonatal respiratory management. Pediatr Neonatol 2022; 63:341-347. [PMID: 35382987 DOI: 10.1016/j.pedneo.2022.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 01/28/2022] [Accepted: 02/14/2022] [Indexed: 11/19/2022] Open
Abstract
Respiratory distress syndrome (RDS) is the major cause of respiratory failure in preterm infants due to immature lung development and surfactant deficiency. Although the concepts and methods of managing respiratory problems in neonates have changed continuously, determining appropriate respiratory treatment with minimal ventilation-induced lung injury and complications is crucially important. This review summarizes neonatal respiratory therapy's advances and available strategies (i.e., exogenous surfactant therapy, noninvasive ventilation, and different ventilation modes), focusing on RDS management.
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Affiliation(s)
- I-Ling Chen
- Department of Respiratory Therapy, College of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, San Ming District, Kaohsiung, Taiwan
| | - Hsiu-Lin Chen
- Department of Respiratory Therapy, College of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, San Ming District, Kaohsiung, Taiwan; Department of Pediatrics, Kaohsiung Medical University Hospital, No. 100, Tzyou 1st Road, San Ming District, Kaohsiung, Taiwan.
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5
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Hayati H, Feng Y, Hinsdale M. Inter-species Variabilities of Droplet Transport, Size Change, and Deposition in Human and Rat Respiratory Systems: An In Silico Study. JOURNAL OF AEROSOL SCIENCE 2021; 154:105761. [PMID: 33776134 PMCID: PMC7990120 DOI: 10.1016/j.jaerosci.2021.105761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
To speculate on human responses from animal studies, scale-up factors (body weight, lung volume, or lung surface area ratios) are currently used to extrapolate aerosol lung deposition from animal to human. However, those existing scale-up methods between animals and humans neglected two important inter-subject variability factors: (1) the effect of anatomical differences in respiratory systems from mouth/nose to peripheral lungs between human and rat, and (2) the effect of spatial distributions and temporal evolutions of temperature and relative humidity (RH) on droplet size change dynamics between the two species. To test the above-mentioned inter-species variability effects on droplet fates in pulmonary routes and generate correlations as a precise scale-up method for lung deposition estimation, this study simulated the transport of pure-water droplets in both human and Sprague-Dawley (SD) rat respiratory systems. Employing an experimentally validated Euler-Lagrange based Computational Fluid-Particle Dynamics (CFPD) model, simulations were performed for droplets with Stk/Fr between 8.36×10-5 and 1.25×10-2. Droplets were inhaled through human and rat nostrils with resting breathing conditions. Numerical results indicate that RH becomes uniformly distributed in rat airways sooner than in human airways, which significantly influences droplet size change dynamics and the resultant trajectories in pulmonary paths. Using the Stokes-Froude dimensionless number group (i.e., Stk/Fr) as the independent variable, the regional deposition fractions and evaporation fractions in both rat and human respiratory systems collapsed into unified correlations. The correlations can be used as a new rat-to-human scale-up method, estimating the lung depositions with consideration of anatomical differences. Furthermore, the necessity to employ realistic RH and temperature boundary conditions at airway walls was also confirmed for the accurate prediction of droplet size change using CFPD. Employing idealized boundary conditions leads the droplets to evaporate slower and deposit more than using realistic RH and temperature boundary conditions.
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Affiliation(s)
- Hamideh Hayati
- School of Chemical Engineering, Oklahoma State University, Stillwater, OK, USA
| | - Yu Feng
- School of Chemical Engineering, Oklahoma State University, Stillwater, OK, USA
| | - Myron Hinsdale
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK, USA
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Corcoran T. Carrier Gases and Their Effects on Aerosol Drug Delivery. J Aerosol Med Pulm Drug Deliv 2021; 34:71-78. [PMID: 33691471 DOI: 10.1089/jamp.2021.29035.tc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Carrier gases provide the medium for delivery of inhaled aerosol therapies. The physical properties of these gases substantially affect both fluid and aerosol mechanics in the lung. Gas density affects both the pressure/flow relationship in the airways and the extent of turbulence within the flow. These physical properties also affect the operation of some components of respiratory and aerosol drug delivery equipment. The lower resistance associated with breathing low density gases has prompted many studies of therapeutic applications. This includes the respiration of helium-oxygen gas mixtures to improve oxygenation and carbon dioxide removal, and the use of these gases to improve the delivery of inhaled medications. Results of these studies have been mixed but meta-analyses indicate a benefit of helium-oxygen respiration for croup and bronchiolitis and for bronchodilator delivery in obstructive disease. Some of the variability demonstrated in these studies is likely associated with specific technical aspects of how the gases are delivered. The utility of alternate carrier gases for aerosol delivery would be facilitated by simultaneous assessment of both aerosol deposition and clinical effect during studies. Previous successful applications may offer a basis for improved delivery system designs that fully realize the effects that might be available with these gases.
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Affiliation(s)
- Tim Corcoran
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania USA
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Bass K, Farkas D, Hassan A, Bonasera S, Hindle M, Longest PW. High-Efficiency Dry Powder Aerosol Delivery to Children: Review and Application of New Technologies. JOURNAL OF AEROSOL SCIENCE 2021; 153:105692. [PMID: 33716317 PMCID: PMC7945982 DOI: 10.1016/j.jaerosci.2020.105692] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
While dry powder aerosol formulations offer a number of advantages, their use in children is often limited due to poor lung delivery efficiency and difficulties with consistent dry powder inhaler (DPI) usage. Both of these challenges can be attributed to the typical use of adult devices in pediatric subjects and a lack of pediatric-specific DPI development. In contrast, a number of technologies have recently been developed or progressed that can substantially improve the efficiency and reproducibility of DPI use in children including: (i) nose-to-lung administration with small particles, (ii) active positive-pressure devices, (iii) structures to reduce turbulence and jet momentum, and (iv) highly dispersible excipient enhanced growth particle formulations. In this study, these technologies and their recent development are first reviewed in depth. A case study is then considered in which these technologies are simultaneously applied in order to enable the nose-to-lung administration of dry powder aerosol to children with cystic fibrosis (CF). Using a combination of computational fluid dynamics (CFD) analysis and realistic in vitro experiments, device performance, aerosol size increases and lung delivery efficiency are considered for pediatric-CF subjects in the age ranges of 2-3, 5-6 and 9-10 years old. Results indicate that a new 3D rod array structure significantly improves performance of a nasal cannula reducing interface loss by a factor of 1.5-fold and produces a device emitted mass median aerodynamic diameter (MMAD) of 1.67 μm. For all ages considered, approximately 70% of the loaded dose reaches the lower lung beyond the lobar bronchi. Moreover, significant and rapid size increase of the aerosol is observed beyond the larynx and illustrates the potential for targeting lower airway deposition. In conclusion, concurrent CFD and realistic in vitro analysis indicates that a combination of multiple new technologies can be implemented to overcome obstacles that currently limit the use of DPIs in children as young as two years of age.
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Affiliation(s)
- Karl Bass
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
| | - Dale Farkas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
| | - Amr Hassan
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
| | - Serena Bonasera
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
| | - P. Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
- Author Contact Information: Dr. Worth Longest, PhD, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA 23284-3015, Phone: (804)-827-7023, Fax: (804)-827-7030,
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8
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CFD Guided Optimization of Nose-to-Lung Aerosol Delivery in Adults: Effects of Inhalation Waveforms and Synchronized Aerosol Delivery. Pharm Res 2020; 37:199. [PMID: 32968848 DOI: 10.1007/s11095-020-02923-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/01/2020] [Indexed: 12/27/2022]
Abstract
PURPOSE The objective of this study was to optimize nose-to-lung aerosol delivery in an adult upper airway model using computational fluid dynamics (CFD) simulations in order to guide subsequent human subject aerosol delivery experiments. METHODS A CFD model was developed that included a new high-flow nasal cannula (HFNC) and pharmaceutical aerosol delivery unit, nasal cannula interface, and adult upper airway geometry. Aerosol deposition predictions in the system were validated with existing and new experimental results. The validated CFD model was then used to explore aerosol delivery parameters related to synchronizing aerosol generation with inhalation and inhalation flow rate. RESULTS The low volume of the new HFNC unit minimized aerosol transit time (0.2 s) and aerosol bolus spread (0.1 s) enabling effective synchronization of aerosol generation with inhalation. For aerosol delivery correctly synchronized with inhalation, a small particle excipient-enhanced growth delivery strategy reduced nasal cannula and nasal depositional losses each by an order of magnitude and enabled ~80% of the nebulized dose to reach the lungs. Surprisingly, nasal deposition was not sensitive to inhalation flow rate due to use of a nasal cannula interface with co-flow inhaled air and the small initial particle size. CONCLUSIONS The combination of correct aerosol synchronization and small particle size enabled high efficiency nose-to-lung aerosol delivery in adults, which was not sensitive to inhalation flow rate.
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9
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Dugernier J, Reychler G, Vecellio L, Ehrmann S. Nasal High-Flow Nebulization for Lung Drug Delivery: Theoretical, Experimental, and Clinical Application. J Aerosol Med Pulm Drug Deliv 2019; 32:341-351. [DOI: 10.1089/jamp.2019.1524] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Jonathan Dugernier
- Institut de Recherche Expérimentale et Clinique (IREC), Pneumologie, ORL & Dermatologie, Cliniques universitaires Saint-Luc, Brussels, Belgium
- Soins Intensifs, Cliniques universitaires Saint-Luc, Brussels, Belgium
- Médecine Physique, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | - Grégory Reychler
- Institut de Recherche Expérimentale et Clinique (IREC), Pneumologie, ORL & Dermatologie, Cliniques universitaires Saint-Luc, Brussels, Belgium
- Service de pneumologie, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | - Laurent Vecellio
- Centre d'études des pathologies respiratoires, INSERM U1100, Faculté de médecine, Université de Tours, Tours, France
| | - Stephan Ehrmann
- Centre d'études des pathologies respiratoires, INSERM U1100, Faculté de médecine, Université de Tours, Tours, France
- Médecine intensive réanimation, Centre d'investigation clinique CIC INSERM 1415, CHRU de Tours, Tours, France
- CRICS-TriggerSep Research Network
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10
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Choi J, LeBlanc LJ, Choi S, Haghighi B, Hoffman EA, O'Shaughnessy P, Wenzel SE, Castro M, Fain S, Jarjour N, Schiebler ML, Denlinger L, Delvadia R, Walenga R, Babiskin A, Lin CL. Differences in Particle Deposition Between Members of Imaging-Based Asthma Clusters. J Aerosol Med Pulm Drug Deliv 2019; 32:213-223. [PMID: 30888242 PMCID: PMC6685197 DOI: 10.1089/jamp.2018.1487] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 01/12/2019] [Indexed: 12/13/2022] Open
Abstract
Background: Four computed tomography (CT) imaging-based clusters have been identified in a study of the Severe Asthma Research Program (SARP) cohort and have been significantly correlated with clinical and demographic metrics (J Allergy Clin Immunol 2017; 140:690-700.e8). We used a computational fluid dynamics (CFD) model to investigate air flow and aerosol deposition within imaging archetypes representative of the four clusters. Methods: CFD simulations for air flow and 1-8 μm particle transport were performed using CT-based airway models from two healthy subjects and eight asthma subjects. The subject selection criterion was based on the discriminant imaging-based flow-related variables of J(Total) (average local volume expansion in the total lung) and Dh*(sLLL) (normalized airway hydraulic diameter in the left lower lobe), where reduced J(Total) and Dh*(sLLL) indicate reduced regional ventilation and airway constriction, respectively. The analysis focused on the comparisons between all clusters with respect to healthy subjects, between cluster 2 and cluster 4 (nonsevere and severe asthma clusters with airway constriction) and between cluster 3 and cluster 4 (two severe asthma clusters characterized by normal and constricted airways, respectively). Results: Nonsevere asthma cluster 2 and severe asthma cluster 4 subjects characterized by airway constriction had an increase in the deposition fraction (DF) in the left lower lobe. Constricted flows impinged on distal bifurcations resulting in large depositions. Although both cluster 3 (without constriction) and cluster 4 (with constriction) were severe asthma, they exhibited different particle deposition patterns with increasing particle size. The statistical analysis showed that Dh*(sLLL) plays a more important role in particle deposition than J(Total), and regional flow fraction is correlated with DF among lobes for smaller particles. Conclusions: We demonstrated particle deposition characteristics associated with cluster-specific imaging-based metrics such as airway constriction, which could pertain to the design of future drug delivery improvements.
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Affiliation(s)
- Jiwoong Choi
- Department of Mechanical Engineering, The University of Iowa, Iowa City, Iowa
- IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
| | - Lawrence J. LeBlanc
- Department of Mechanical Engineering, The University of Iowa, Iowa City, Iowa
- IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
| | - Sanghun Choi
- School of Mechanical Engineering, Kyungpook National University, Daegu, Republic of Korea
| | - Babak Haghighi
- Department of Mechanical Engineering, The University of Iowa, Iowa City, Iowa
- IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
| | - Eric A. Hoffman
- Department of Radiology, The University of Iowa, Iowa City, Iowa
| | - Patrick O'Shaughnessy
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, Iowa
| | - Sally E. Wenzel
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Mario Castro
- Departments of Internal Medicine and Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Sean Fain
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Nizar Jarjour
- Division of Pulmonary Medicine and Critical Care, Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Mark L. Schiebler
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Loren Denlinger
- Division of Pulmonary Medicine and Critical Care, Department of Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
| | - Renishkumar Delvadia
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland
| | - Ross Walenga
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland
| | - Andrew Babiskin
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland
| | - Ching-Long Lin
- Department of Mechanical Engineering, The University of Iowa, Iowa City, Iowa
- IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
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Longest W, Spence B, Hindle M. Devices for Improved Delivery of Nebulized Pharmaceutical Aerosols to the Lungs. J Aerosol Med Pulm Drug Deliv 2019; 32:317-339. [PMID: 31287369 DOI: 10.1089/jamp.2018.1508] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Nebulizers have a number of advantages for the delivery of inhaled pharmaceutical aerosols, including the use of aqueous formulations and the ability to deliver process-sensitive proteins, peptides, and biological medications. A frequent disadvantage of nebulized aerosols is poor lung delivery efficiency, which wastes valuable medications, increases delivery times, and may increase side effects of the medication. A focus of previous development efforts and previous nebulizer reviews, has been an improvement of the underlying nebulization technology controlling the breakup of a liquid into droplets. However, for a given nebulization technology, a wide range of secondary devices and strategies can be implemented to significantly improve lung delivery efficiency of the aerosol. This review focuses on secondary devices and technologies that can be implemented to improve the lung delivery efficiency of nebulized aerosols and potentially target the region of drug delivery within the lungs. These secondary devices may (1) modify the aerosol size distribution, (2) synchronize aerosol delivery with inhalation, (3) reduce system depositional losses at connection points, (4) improve the patient interface, or (5) guide patient inhalation. The development of these devices and technologies is also discussed, which often includes the use of computational fluid dynamic simulations, three-dimensional printing and rapid prototype device and airway model construction, realistic in vitro experiments, and in vivo analysis. Of the devices reviewed, the implementation of streamlined components may be the most direct and lowest cost approach to enhance aerosol delivery efficiency within nonambulatory nebulizer systems. For applications involving high-dose medications or precise dose administration, the inclusion of active devices to control aerosol size, guide inhalation, and synchronize delivery with inhalation hold considerable promise.
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Affiliation(s)
- Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia.,Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia
| | - Benjamin Spence
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia
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12
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Longest PW, Bass K, Dutta R, Rani V, Thomas ML, El-Achwah A, Hindle M. Use of computational fluid dynamics deposition modeling in respiratory drug delivery. Expert Opin Drug Deliv 2019; 16:7-26. [PMID: 30463458 PMCID: PMC6529297 DOI: 10.1080/17425247.2019.1551875] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 11/20/2018] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Respiratory drug delivery is a surprisingly complex process with a number of physical and biological challenges. Computational fluid dynamics (CFD) is a scientific simulation technique that is capable of providing spatially and temporally resolved predictions of many aspects related to respiratory drug delivery from initial aerosol formation through respiratory cellular drug absorption. AREAS COVERED This review article focuses on CFD-based deposition modeling applied to pharmaceutical aerosols. Areas covered include the development of new complete-airway CFD deposition models and the application of these models to develop a next-generation of respiratory drug delivery strategies. EXPERT OPINION Complete-airway deposition modeling is a valuable research tool that can improve our understanding of pharmaceutical aerosol delivery and is already supporting medical hypotheses, such as the expected under-treatment of the small airways in asthma. These complete-airway models are also being used to advance next-generation aerosol delivery strategies, like controlled condensational growth. We envision future applications of CFD deposition modeling to reduce the need for human subject testing in developing new devices and formulations, to help establish bioequivalence for the accelerated approval of generic inhalers, and to provide valuable new insights related to drug dissolution and clearance leading to microdosimetry maps of drug absorption.
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Affiliation(s)
- P. Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
| | - Karl Bass
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Rabijit Dutta
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Vijaya Rani
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Morgan L. Thomas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Ahmad El-Achwah
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
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13
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Farkas D, Hindle M, Longest PW. Efficient Nose-to-Lung Aerosol Delivery with an Inline DPI Requiring Low Actuation Air Volume. Pharm Res 2018; 35:194. [PMID: 30132207 DOI: 10.1007/s11095-018-2473-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/03/2018] [Indexed: 11/28/2022]
Abstract
PURPOSE To demonstrate efficient aerosol delivery through an in vitro nasal model using a dry powder inhaler (DPI) requiring low actuation air volumes (LV) applied during low-flow nasal cannula (LFNC) therapy. METHODS A previously developed LV-DPI was connected to a LFNC system with 4 mm diameter tubing. System connections and the nasal cannula interface were replaced with streamlined components. To simulate nasal respiration, an in vitro nasal model was connected to a downstream lung simulator that produced either passive or deep nasal respiration. Performance of a commercial mesh nebulizer system was also considered. RESULTS For the optimized system, steady state cannula emitted dose was 75% of the capsule loaded dose. With cyclic nasal breathing, delivery efficiency to the tracheal filter was 53-55% of the loaded dose, which was just under the design target of 60%. Compared with a commercially available mesh nebulizer, the optimal LV-DPI was 40-fold more efficient and 150 times faster in terms of delivering aerosol to the lungs. CONCLUSIONS The optimized LV-DPI system is capable of high efficiency lung delivery of powder aerosols through a challenging nasal cannula interface.
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Affiliation(s)
- Dale Farkas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015 Richmond, Virginia, 23284-3015, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University Richmond, Virginia, USA
| | - P Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015 Richmond, Virginia, 23284-3015, USA. .,Department of Pharmaceutics, Virginia Commonwealth University Richmond, Virginia, USA.
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Application of an inline dry powder inhaler to deliver high dose pharmaceutical aerosols during low flow nasal cannula therapy. Int J Pharm 2018; 546:1-9. [PMID: 29733972 DOI: 10.1016/j.ijpharm.2018.05.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/30/2018] [Accepted: 05/04/2018] [Indexed: 11/21/2022]
Abstract
Inline dry powder inhalers (DPIs) offer a potentially effective option to deliver high dose inhaled medications simultaneously with mechanical ventilation. The objective of this study was to develop an inline DPI that is actuated using a low volume of air (LV-DPI) to efficiently deliver pharmaceutical aerosols during low flow nasal cannula (LFNC) therapy. A characteristic feature of the new inline LV-DPIs was the use of hollow capillary tubes that both pierced the capsule and provided a pathway for inlet air and exiting aerosol. Aerosolization characteristics, LFNC depositional losses and emitted dose (ED) were determined using 10 mg powder masses of a small-particle excipient enhanced growth (EEG) formulation. While increasing the number of inlet capillaries from one to three did not improve performance, retracting the inlet and outlet capillaries did improve ED by over 30%. It was theorized that high quality performance requires both high turbulent energy to deaggregate the powder and high wall shear stresses to minimize capsule retention. Best case performance included a device ED of approximately 85% (of loaded dose) and device emitted mass median aerodynamic diameter of 1.77 µm. Maximum ED through the LFNC system and small diameter (4 mm) nasal cannula was approximately 65% of the loaded dose. Potential applications of this device include the delivery of high dose inhaled medications such as surfactants, antibiotics, mucolytics, and anti-inflammatories.
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Walenga RL, Longest PW, Kaviratna A, Hindle M. Aerosol Drug Delivery During Noninvasive Positive Pressure Ventilation: Effects of Intersubject Variability and Excipient Enhanced Growth. J Aerosol Med Pulm Drug Deliv 2017; 30:190-205. [PMID: 28075194 DOI: 10.1089/jamp.2016.1343] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Nebulized aerosol drug delivery during the administration of noninvasive positive pressure ventilation (NPPV) is commonly implemented. While studies have shown improved patient outcomes for this therapeutic approach, aerosol delivery efficiency is reported to be low with high variability in lung-deposited dose. Excipient enhanced growth (EEG) aerosol delivery is a newly proposed technique that may improve drug delivery efficiency and reduce intersubject aerosol delivery variability when coupled with NPPV. MATERIALS AND METHODS A combined approach using in vitro experiments and computational fluid dynamics (CFD) was used to characterize aerosol delivery efficiency during NPPV in two new nasal cavity models that include face mask interfaces. Mesh nebulizer and in-line dry powder inhaler (DPI) sources of conventional and EEG aerosols were both considered. RESULTS Based on validated steady-state CFD predictions, EEG aerosol delivery improved lung penetration fraction (PF) values by factors ranging from 1.3 to 6.4 compared with conventional-sized aerosols. Furthermore, intersubject variability in lung PF was very high for conventional aerosol sizes (relative differences between subjects in the range of 54.5%-134.3%) and was reduced by an order of magnitude with the EEG approach (relative differences between subjects in the range of 5.5%-17.4%). Realistic in vitro experiments of cyclic NPPV demonstrated similar trends in lung delivery to those observed with the steady-state simulations, but with lower lung delivery efficiencies. Reaching the lung delivery efficiencies reported with the steady-state simulations of 80%-90% will require synchronization of aerosol administration during inspiration and reducing the size of the EEG aerosol delivery unit. CONCLUSIONS The EEG approach enabled high-efficiency lung delivery of aerosols administered during NPPV and reduced intersubject aerosol delivery variability by an order of magnitude. Use of an in-line DPI device that connects to the NPPV mask appears to be a convenient method to rapidly administer an EEG aerosol and synchronize the delivery with inspiration.
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Affiliation(s)
- Ross L Walenga
- 1 Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University , Richmond, Virginia
| | - P Worth Longest
- 1 Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University , Richmond, Virginia.,2 Department of Pharmaceutics, Virginia Commonwealth University , Richmond, Virginia
| | - Anubhav Kaviratna
- 2 Department of Pharmaceutics, Virginia Commonwealth University , Richmond, Virginia
| | - Michael Hindle
- 2 Department of Pharmaceutics, Virginia Commonwealth University , Richmond, Virginia
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16
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Rygg A, Longest PW. Absorption and Clearance of Pharmaceutical Aerosols in the Human Nose: Development of a CFD Model. J Aerosol Med Pulm Drug Deliv 2016; 29:416-431. [PMID: 26824178 PMCID: PMC8662553 DOI: 10.1089/jamp.2015.1252] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE The objective of this study was to develop a computational fluid dynamics (CFD) model to predict the deposition, dissolution, clearance, and absorption of pharmaceutical particles in the human nasal cavity. METHODS A three-dimensional nasal cavity geometry was converted to a surface-based model, providing an anatomically-accurate domain for the simulations. Particle deposition data from a commercial nasal spray product was mapped onto the surface model, and a mucus velocity field was calculated and validated with in vivo nasal clearance rates. A submodel for the dissolution of deposited particles was developed and validated based on comparisons to existing in vitro data for multiple pharmaceutical products. A parametric study was then performed to assess sensitivity of epithelial drug uptake to model conditions and assumptions. RESULTS The particle displacement distance (depth) in the mucus layer had a modest effect on overall drug absorption, while the mucociliary clearance rate was found to be primarily responsible for drug uptake over the timescale of nasal clearance for the corticosteroid mometasone furoate (MF). The model revealed that drug deposition in the nasal vestibule (NV) could slowly be transported into the main passage (MP) and then absorbed through connection of the liquid layer in the NV and MP regions. As a result, high intersubject variability in cumulative uptake was predicted, depending on the length of time the NV dose was left undisturbed without blowing or wiping the nose. CONCLUSIONS This study has developed, for the first time, a complete CFD model of nasal aerosol delivery from the point of spray formation through absorption at the respiratory epithelial surface. For the development and assessment of nasal aerosol products, this CFD-based in silico model provides a new option to complement existing in vitro nasal cast studies of deposition and in vivo imaging experiments of clearance.
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Affiliation(s)
- Alex Rygg
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
| | - P. Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
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Michotte JB, Staderini E, Le Pennec D, Dugernier J, Rusu R, Roeseler J, Vecellio L, Liistro G, Reychler G. In Vitro Comparison of a Vibrating Mesh Nebulizer Operating in Inspiratory Synchronized and Continuous Nebulization Modes During Noninvasive Ventilation. J Aerosol Med Pulm Drug Deliv 2016; 29:328-36. [PMID: 27310926 DOI: 10.1089/jamp.2015.1243] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
UNLABELLED Backround: Coupling nebulization with noninvasive ventilation (NIV) has been shown to be effective in patients with respiratory diseases. However, a breath-synchronized nebulization option that could potentially improve drug delivery by limiting drug loss during exhalation is currently not available on bilevel ventilators. The aim of this in vitro study was to compare aerosol delivery of amikacin with a vibrating mesh nebulizer coupled to a single-limb circuit bilevel ventilator, using conventional continuous (Conti-Neb) and experimental inspiratory synchronized (Inspi-Neb) nebulization modes. METHODS Using an adult lung bench model of NIV, we tested a vibrating mesh device coupled with a bilevel ventilator in both nebulization modes. Inspi-Neb delivered aerosol only during the whole inspiratory phase, whereas Conti-Neb delivered aerosol continuously. The nebulizer was charged with amikacin solution (250 mg/3 mL) and placed at two different positions: between the lung and exhalation port and between the ventilator and exhalation port. Inhaled, expiratory wasted and circuit lost doses were assessed by residual gravimetric method. Particle size distribution of aerosol delivered at the outlet of the ventilator circuit during both nebulization modes was measured by laser diffraction method. RESULTS Regardless of the nebulizer position, Inspi-Neb produced higher inhaled dose (p < 0.01; +6.3% to +16.8% of the nominal dose), lower expiratory wasted dose (p < 0.05; -2.7% to -42.6% of the nominal dose), and greater respirable dose (p < 0.01; +8.4% to +15.2% of the nominal dose) than Conti-Neb. The highest respirable dose was found with the nebulizer placed between the lung and exhalation port (48.7% ± 0.3% of the nominal dose). CONCLUSIONS During simulated NIV with a single-limb circuit bilevel ventilator, the use of inspiratory synchronized vibrating mesh nebulization improves respirable dose and reduces drug loss of amikacin compared with continuous vibrating mesh nebulization.
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Affiliation(s)
- Jean-Bernard Michotte
- 1 Western Switzerland University of Applied Sciences-Haute Ecole de Santé Vaud , Filière Physiothérapie, Switzerland .,6 Cliniques Universitaires Saint-Luc, Service de Pneumologie; Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC) , Pôle de Pneumologie, ORL & Dermatologie, Belgium
| | - Enrico Staderini
- 2 Western Switzerland University of Applied Sciences-Haute Ecole d'Ingénierie et de Gestion du Canton de Vaud , Switzerland
| | - Deborah Le Pennec
- 3 Centre d'Etude des Pathologies Respiratoires, INSERM, UMR 1100, Equipe "aérosolthérapie et biomédicaments à visée respiratoire," Université de Tours , Faculté de Médecine, France
| | - Jonathan Dugernier
- 4 Cliniques Universitaires Saint-Luc , Service des soins intensifs, Belgium
| | - Rares Rusu
- 2 Western Switzerland University of Applied Sciences-Haute Ecole d'Ingénierie et de Gestion du Canton de Vaud , Switzerland
| | - Jean Roeseler
- 4 Cliniques Universitaires Saint-Luc , Service des soins intensifs, Belgium
| | - Laurent Vecellio
- 3 Centre d'Etude des Pathologies Respiratoires, INSERM, UMR 1100, Equipe "aérosolthérapie et biomédicaments à visée respiratoire," Université de Tours , Faculté de Médecine, France .,5 Aerodrug, DTF, Faculty of Medicine, Tours University , France
| | - Giuseppe Liistro
- 6 Cliniques Universitaires Saint-Luc, Service de Pneumologie; Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC) , Pôle de Pneumologie, ORL & Dermatologie, Belgium
| | - Grégory Reychler
- 6 Cliniques Universitaires Saint-Luc, Service de Pneumologie; Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC) , Pôle de Pneumologie, ORL & Dermatologie, Belgium
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Carrigy NB, Ruzycki CA, Golshahi L, Finlay WH. Pediatric in vitro and in silico models of deposition via oral and nasal inhalation. J Aerosol Med Pulm Drug Deliv 2015; 27:149-69. [PMID: 24870701 DOI: 10.1089/jamp.2013.1075] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Respiratory tract deposition models provide a useful method for optimizing the design and administration of inhaled pharmaceutical aerosols, and can be useful for estimating exposure risks to inhaled particulate matter. As aerosol must first pass through the extrathoracic region prior to reaching the lungs, deposition in this region plays an important role in both cases. Compared to adults, much less extrathoracic deposition data are available with pediatric subjects. Recently, progress in magnetic resonance imaging and computed tomography scans to develop pediatric extrathoracic airway replicas has facilitated addressing this issue. Indeed, the use of realistic replicas for benchtop inhaler testing is now relatively common during the development and in vitro evaluation of pediatric respiratory drug delivery devices. Recently, in vitro empirical modeling studies using a moderate number of these realistic replicas have related airway geometry, particle size, fluid properties, and flow rate to extrathoracic deposition. Idealized geometries provide a standardized platform for inhaler testing and exposure risk assessment and have been designed to mimic average in vitro deposition in infants and children by replicating representative average geometrical dimensions. In silico mathematical models have used morphometric data and aerosol physics to illustrate the relative importance of different deposition mechanisms on respiratory tract deposition. Computational fluid dynamics simulations allow for the quantification of local deposition patterns and an in-depth examination of aerosol behavior in the respiratory tract. Recent studies have used both in vitro and in silico deposition measurements in realistic pediatric airway geometries to some success. This article reviews the current understanding of pediatric in vitro and in silico deposition modeling via oral and nasal inhalation.
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Affiliation(s)
- Nicholas B Carrigy
- 1 Aerosol Research Laboratory of Alberta, Department of Mechanical Engineering, University of Alberta , Edmonton, Alberta, Canada T6G 2G8
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Frank-Ito DO, Schulz K, Vess G, Witsell DL. Changes in aerodynamics during vocal cord dysfunction. Comput Biol Med 2015; 57:116-22. [DOI: 10.1016/j.compbiomed.2014.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 12/03/2014] [Accepted: 12/05/2014] [Indexed: 12/01/2022]
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Walenga RL, Tian G, Hindle M, Yelverton J, Dodson K, Longest PW. Variability in Nose-to-Lung Aerosol Delivery. JOURNAL OF AEROSOL SCIENCE 2014; 78:11-29. [PMID: 25308992 PMCID: PMC4187112 DOI: 10.1016/j.jaerosci.2014.08.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Nasal delivery of lung targeted pharmaceutical aerosols is ideal for drugs that need to be administered during high flow nasal cannula (HFNC) gas delivery, but based on previous studies losses and variability through both the delivery system and nasal cavity are expected to be high. The objective of this study was to assess the variability in aerosol delivery through the nose to the lungs with a nasal cannula interface for conventional and excipient enhanced growth (EEG) delivery techniques. A database of nasal cavity computed tomography (CT) scans was collected and analyzed, from which four models were selected to represent a wide range of adult anatomies, quantified based on the nasal surface area-to-volume ratio (SA/V). Computational fluid dynamics (CFD) methods were validated with existing in vitro data and used to predict aerosol delivery through a streamlined nasal cannula and the four nasal models at a steady state flow rate of 30 L/min. Aerosols considered were solid particles for EEG delivery (initial 0.9 μm and 1.5 μm aerodynamic diameters) and conventional droplets (5 μm) for a control case. Use of the EEG approach was found to reduce depositional losses in the nasal cavity by an order of magnitude and substantially reduce variability. Specifically, for aerosol deposition efficiency in the four geometries, the 95% confidence intervals (CI) for 0.9 and 5 μm aerosols were 2.3-3.1 and 15.5-66.3%, respectively. Simulations showed that the use of EEG as opposed to conventional methods improved delivered dose of aerosols through the nasopharynx, expressed as penetration fraction (PF), by approximately a factor of four. Variability of PF, expressed by the coefficient of variation (CV), was reduced by a factor of four with EEG delivery compared with the control case. Penetration fraction correlated well with SA/V for larger aerosols, but smaller aerosols showed some dependence on nasopharyngeal exit hydraulic diameter. In conclusion, results indicated that the EEG technique not only improved lung aerosol delivery, but largely eliminated variability in both nasal depositional loss and lung PF in a newly developed set of nasal airway models.
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Affiliation(s)
- Ross L Walenga
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
| | - Geng Tian
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
| | - Joshua Yelverton
- Department of Otolaryngology – Head and Neck Surgery, Virginia Commonwealth University, Richmond, VA
| | - Kelley Dodson
- Department of Otolaryngology – Head and Neck Surgery, Virginia Commonwealth University, Richmond, VA
| | - P. Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA
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21
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Longest PW, Golshahi L, Behara SRB, Tian G, Farkas DR, Hindle M. Efficient Nose-to-Lung (N2L) Aerosol Delivery with a Dry Powder Inhaler. J Aerosol Med Pulm Drug Deliv 2014; 28:189-201. [PMID: 25192072 DOI: 10.1089/jamp.2014.1158] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
PURPOSE Delivering aerosols to the lungs through the nasal route has a number of advantages, but its use has been limited by high depositional loss in the extrathoracic airways. The objective of this study was to evaluate the nose-to-lung (N2L) delivery of excipient enhanced growth (EEG) formulation aerosols generated with a new inline dry powder inhaler (DPI). The device was also adapted to enable aerosol delivery to a patient simultaneously receiving respiratory support from high flow nasal cannula (HFNC) therapy. METHODS The inhaler delivered the antibiotic ciprofloxacin, which was formulated as submicrometer combination particles containing a hygroscopic excipient prepared by spray-drying. Nose-to-lung delivery was assessed using in vitro and computational fluid dynamics (CFD) methods in an airway model that continued through the upper tracheobronchial region. RESULTS The best performing device contained a 2.3 mm flow control orifice and a 3D rod array with a 3-4-3 rod pattern. Based on in vitro experiments, the emitted dose from the streamlined nasal cannula had a fine particle fraction <5 μm of 95.9% and mass median aerodynamic diameter of 1.4 μm, which was considered ideal for nose-to-lung EEG delivery. With the 2.3-343 device, condensational growth in the airways increased the aerosol size to 2.5-2.7 μm and extrathoracic deposition was <10%. CFD results closely matched the in vitro experiments and predicted that nasal deposition was <2%. CONCLUSIONS The developed DPI produced high efficiency aerosolization with significant size increase of the aerosol within the airways that can be used to enable nose-to-lung delivery and aerosol administration during HFNC therapy.
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Affiliation(s)
- P Worth Longest
- 1Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia.,2Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia
| | - Laleh Golshahi
- 1Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Srinivas R B Behara
- 1Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia.,2Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia
| | - Geng Tian
- 1Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Dale R Farkas
- 1Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Michael Hindle
- 2Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia
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Behara SRB, Longest PW, Farkas DR, Hindle M. Development of high efficiency ventilation bag actuated dry powder inhalers. Int J Pharm 2014; 465:52-62. [PMID: 24508552 PMCID: PMC4051231 DOI: 10.1016/j.ijpharm.2014.01.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 01/30/2014] [Indexed: 01/19/2023]
Abstract
New active dry powder inhaler systems were developed and tested to efficiently aerosolize a carrier-free formulation. To assess inhaler performance, a challenging case study of aerosol lung delivery during high-flow nasal cannula (HFNC) therapy was selected. The active delivery system consisted of a ventilation bag for actuating the device, the DPI containing a flow control orifice and 3D rod array, and streamlined nasal cannula with separate inlets for the aerosol and HFNC therapy gas. In vitro experiments were conducted to assess deposition in the device, emitted dose (ED) from the nasal cannula, and powder deaggregation. The best performing systems achieved EDs of 70-80% with fine particle fractions <5 μm of 65-85% and mass median aerodynamic diameters of 1.5 μm, which were target conditions for controlled condensational growth aerosol delivery. Decreasing the size of the flow control orifice from 3.6 to 2.3mm reduced the flow rate through the system with manual bag actuations from an average of 35 to 15LPM, while improving ED and aerosolization performance. The new devices can be applied to improve aerosol delivery during mechanical ventilation, nose-to-lung aerosol administration, and to assist patients that cannot reproducibly use passive DPIs.
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Affiliation(s)
- Srinivas R B Behara
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States; Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States
| | - P Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States; Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States.
| | - Dale R Farkas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States
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Tian G, Hindle M, Longest PW. Targeted Lung Delivery of Nasally Administered Aerosols. AEROSOL SCIENCE AND TECHNOLOGY : THE JOURNAL OF THE AMERICAN ASSOCIATION FOR AEROSOL RESEARCH 2014; 48:434-449. [PMID: 24932058 PMCID: PMC4051279 DOI: 10.1080/02786826.2014.887829] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Using the nasal route to deliver pharmaceutical aerosols to the lungs has a number of advantages including co-administration during non-invasive ventilation. The objective of this study was to evaluate the growth and deposition characteristics of nasally administered aerosol throughout the conducting airways based on delivery with streamlined interfaces implementing two forms of controlled condensational growth technology. Characteristic conducting airways were considered including a nose-mouth-throat (NMT) geometry, complete upper tracheobronchial (TB) model through the third bifurcation (B3), and stochastic individual path (SIP) model to the terminal bronchioles (B15). Previously developed streamlined nasal cannula interfaces were used for the delivery of submicrometer particles using either enhanced condensational growth (ECG) or excipient enhanced growth (EEG) techniques. Computational fluid dynamics (CFD) simulations predicted aerosol transport, growth and deposition for a control (4.7 μm) and three submicrometer condensational aerosols with budesonide as a model insoluble drug. Depositional losses with condensational aerosols in the cannula and NMT were less than 5% of the initial dose, which represents an order-of-magnitude reduction compared to the control. The condensational growth techniques increased the TB dose by a factor of 1.1-2.6x, delivered at least 70% of the dose to the alveolar region, and produced final aerosol sizes ≥2.5 μm. Compared to multiple commercial orally inhaled products, the nose-to-lung delivery approach increased dose to the biologically important lower TB region by factors as large as 35x. In conclusion, nose-to-lung delivery with streamlined nasal cannulas and condensational aerosols was highly efficient and targeted deposition to the lower TB and alveolar regions.
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Affiliation(s)
- Geng Tian
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia, USA
| | - P. Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, Virginia, USA
- Address correspondence to: P. Worth Longest, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA 23284-3015, USA.
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The use of condensational growth methods for efficient drug delivery to the lungs during noninvasive ventilation high flow therapy. Pharm Res 2013; 30:2917-30. [PMID: 23801087 DOI: 10.1007/s11095-013-1123-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE The objective of this study was to evaluate the delivery of nasally administered aerosols to the lungs during noninvasive ventilation using controlled condensational growth techniques. METHODS An optimized mixer, combined with a mesh nebulizer, was used to generate submicrometer aerosol particles using drug alone (albuterol sulfate) and with mannitol or sodium chloride added as hygroscopic excipients. The deposition and growth of these particles were evaluated in an adult nose-mouth-throat (NMT) model using in vitro experimental methods and computational fluid dynamics simulations. RESULTS Significant improvement in the lung dose (3-4× increase) was observed using excipient enhanced growth (EEG) and enhanced condensational growth (ECG) delivery modes compared to control studies performed with a conventional size aerosol (~5 μm). This was due to reduced device retention and minimal deposition in the NMT airways. Increased condensational growth of the initially submicrometer particles was observed using the ECG mode and in the presence of hygroscopic excipients. CFD predictions for regional drug deposition and aerosol size increase were in good agreement with the observed experimental results. CONCLUSIONS These controlled condensational growth techniques for the delivery of submicrometer aerosols were found to be highly efficient methods for delivering nasally-administered drugs to the lungs.
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Improving pharmaceutical aerosol delivery during noninvasive ventilation: effects of streamlined components. Ann Biomed Eng 2013; 41:1217-32. [PMID: 23423706 DOI: 10.1007/s10439-013-0759-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 02/04/2013] [Indexed: 10/27/2022]
Abstract
Aerosol delivery efficiency during noninvasive ventilation (NIV) is known to be low (~10%) and is associated with poor outcomes of aerosol therapy. The objective of this study was to demonstrate the benefit of redesigning ventilation circuit components using a streamlining approach to improve aerosol delivery during nasal high flow therapy in adults with a conventional-sized aerosol from a mesh nebulizer. The ventilation circuit consisted of a humidifier, mesh nebulizer, mixing T-connector (with 90° angle), 10 mm tubing, and nasal cannula interface. In vitro experiments and computational fluid dynamics analyses were used to evaluate depositional losses in a system of existing components and a newly proposed streamlined T-connector and cannula at flow rates of 30 and 45 LPM. Streamlined designs reduced deposition in the T-connector by a factor of 4. In the nasal cannula, the streamlined designs reduced depositional losses by factors of 1.25-2.0. With the streamlined designs, the highest emitted dose achieved was >40% for a conventional-sized aerosol at 30 LPM. Streamlined geometries offer an effective method to significantly improve the delivery of aerosols through components of NIV systems. This increase in delivery efficiency is important for new inhaled medications with narrow therapeutic windows, increased costs, or long delivery times.
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Xi J, Kim J, Si XA, Zhou Y. Hygroscopic aerosol deposition in the human upper respiratory tract under various thermo-humidity conditions. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2013; 48:1790-805. [PMID: 24007434 DOI: 10.1080/10934529.2013.823333] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The deposition of hygroscopic aerosols is highly complex in nature, which results from a cumulative effect of dynamic particle growth and the real-time size-specific deposition mechanisms. The objective of this study is to evaluate hygroscopic effects on the particle growth, transport, and deposition of nasally inhaled aerosols across a range of 0.2-2.5 μm in an adult image-based nose-throat model. Temperature and relative humidity fields were simulated using the LRN k-ω turbulence model and species transport model under a spectrum of thermo-humidity conditions. Particle growth and transport were simulated using a well validated Lagrangian tracking model coupled with a user-defined hygroscopic growth module. Results of this study indicate that the saturation level and initial particle size are the two major factors that determine the particle growth rate (d/d0), while the effect of inhalation flow rate is found to be not significant. An empirical correlation of condensation growth of nasally inhaled hygroscopic aerosols in adults has been developed based on a variety of thermo-humidity inhalation conditions. Significant elevated nasal depositions of hygroscopic aerosols could be induced by condensation growth for both sub-micrometer and small micrometer particulates. In particular, the deposition of initially 2.5 μm hygroscopic aerosols was observed to be 5-8 times that of inert particles under warm to hot saturated conditions. Results of this study have important implications in exposure assessment in hot humid environments, where much higher risks may be expected compared to normal conditions.
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Affiliation(s)
- Jinxiang Xi
- Department of Mechanical and Biomedical Engineering, Central Michigan University, Mount Pleasant, Michigan 48858, USA.
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Kim JW, Xi J, Si XA. Dynamic growth and deposition of hygroscopic aerosols in the nasal airway of a 5-year-old child. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:17-39. [PMID: 23293067 DOI: 10.1002/cnm.2490] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 04/05/2012] [Accepted: 04/14/2012] [Indexed: 05/04/2023]
Abstract
Hygroscopic growth within the human respiratory tract can be significant, which may notably alter the behavior and fate of the inhaled aerosols. The objective of this study is to evaluate the hygroscopic effects upon the transport and deposition of nasally inhaled fine-regime aerosols in children. A physiologically realistic nasal-laryngeal airway model was developed based on magnetic resonance imaging of a 5-year-old boy. Temperature and relative humidity field were simulated using the low Reynolds number k - ε turbulence model and chemical specie transport model under a spectrum of four thermo-humidity conditions. Particle growth and transport were simulated using a well validated Lagrangian tracking model coupled with a user-defined hygroscopic growth module. The subsequent aerosol depositions for the four inhalation scenarios were evaluated on a multiscale basis such as total, subregional, and cellular-level depositions. Results of this study show that a supersaturated humid environment is possible in the nasal turbinate region and can lead to significant condensation growth (d / d(0) > 10) of nasally inhaled aerosols. Depositions in the nasal airway can also be greatly enhanced by condensation growth with appropriate inhalation temperature and humidity. For subsaturated and mild inhalation conditions, the hygroscopic effects were found to be nonsignificant for total depositions, while exerting a large impact upon localized depositions.
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Affiliation(s)
- Jong Won Kim
- Department of Systems Engineering, University of Arkansas, Little Rock, AR, U.S.A
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Longest PW, Walenga RL, Son YJ, Hindle M. High-efficiency generation and delivery of aerosols through nasal cannula during noninvasive ventilation. J Aerosol Med Pulm Drug Deliv 2012; 26:266-79. [PMID: 23273243 DOI: 10.1089/jamp.2012.1006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Previous studies have demonstrated the delivery of pharmaceutical aerosols through nasal cannula and the feasibility of enhanced condensational growth (ECG) with a nasal interface. The objectives of this study were to develop a device for generating submicrometer aerosols with minimal depositional loss in the formation process and to improve aerosol delivery efficiencies through nasal cannulas. METHODS A combination of in vitro experiments and computational fluid dynamics (CFD) simulations that used the strengths of each method was applied. Aerosols were formed using a conventional mesh nebulizer, mixed with ventilation gas, and heated to produce submicrometer sizes. An improved version of the mixer and heater unit was developed based on CFD simulations, and performance was verified with experiments. Aerosol delivery was considered through a commercial large-bore adult cannula, a divided (D) design for use with ECG, and a divided and streamlined (DS) design. RESULTS The improved mixer design reduced the total deposition fraction (DF) of drug within the mixer by a factor of 3 compared with an initial version, had a total DF of approximately 10%, and produced submicrometer aerosols at flow rates of 10 and 15 L/min. Compared with the commercial and D designs for submicrometer aerosols, the DS cannula reduced depositional losses by a factor of 2-3 and retained only approximately 5% or less of the nebulized dose at all flow rates considered. For conventional-sized aerosols (3.9 and 4.7 μm), the DS device provided delivery efficiencies of approximately 80% and above at flow rates of 2-15 L/min. CONCLUSIONS Submicrometer aerosols can be formed using a conventional mesh nebulizer and delivered through a nasal cannula with total delivery efficiencies of 80-90%. Streamlining the nasal cannula significantly improved the delivery efficiency of both submicrometer and micrometer aerosols; however, use of submicrometer particles with ECG delivery resulted in overall lower depositional losses.
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Affiliation(s)
- P Worth Longest
- 1 Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University , Richmond, VA 23284
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Longest PW, Spence BM, Holbrook LT, Mossi KM, Son YJ, Hindle M. Production of Inhalable Submicrometer Aerosols from Conventional Mesh Nebulizers for Improved Respiratory Drug Delivery. JOURNAL OF AEROSOL SCIENCE 2012; 51:66-80. [PMID: 22707794 PMCID: PMC3374487 DOI: 10.1016/j.jaerosci.2012.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Submicrometer and nanoparticle aerosols may significantly improve the delivery efficiency, dissolution characteristics, and bioavailability of inhaled pharmaceuticals. The objective of this study was to explore the formation of submicrometer and nanometer aerosols from mesh nebulizers suitable for respiratory drug delivery using experiments and computational fluid dynamics (CFD) modeling. Mesh nebulizers were coupled with add-on devices to promote aerosol drying and the formation of submicrometer particles, as well as to control the inhaled aerosol temperature and relative humidity. Cascade impaction experiments were used to determine the initial mass median aerodynamic diameters of 0.1% albuterol aerosols produced by the AeroNeb commercial (4.69 μm) and lab (3.90 μm) nebulizers and to validate the CFD model in terms of droplet evaporation. Through an appropriate selection of flow rates, nebulizers, and model drug concentrations, submicrometer and nanometer aerosols could be formed with the three devices considered. Based on CFD simulations, a wire heated design was shown to overheat the airstream producing unsafe conditions for inhalation if the aerosol was not uniformly distributed in the tube cross-section or if the nebulizer stopped producing droplets. In comparison, a counter-flow heated design provided sufficient thermal energy to produce submicrometer particles, but also automatically limited the maximum aerosol outlet temperature based on the physics of heat transfer. With the counter-flow design, submicrometer aerosols were produced at flow rates of 5, 15, and 30 LPM, which may be suitable for various forms of oral and nasal aerosol delivery. Thermodynamic conditions of the aerosol stream exiting the counter-flow design were found be in a range of 21-45 °C with relative humidity greater than 40% in some cases, which was considered safe for direct inhalation and advantageous for condensational growth delivery.
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Affiliation(s)
- P. Worth Longest
- Department of Mechanical Engineering Virginia Commonwealth University, Richmond, VA
- Department of Pharmaceutics Virginia Commonwealth University, Richmond, VA
| | - Benjamin M. Spence
- Department of Mechanical Engineering Virginia Commonwealth University, Richmond, VA
| | - Landon T. Holbrook
- Department of Mechanical Engineering Virginia Commonwealth University, Richmond, VA
| | - Karla M. Mossi
- Department of Mechanical Engineering Virginia Commonwealth University, Richmond, VA
| | - Yoen-Ju Son
- Department of Pharmaceutics Virginia Commonwealth University, Richmond, VA
| | - Michael Hindle
- Department of Pharmaceutics Virginia Commonwealth University, Richmond, VA
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Longest PW, Holbrook LT. In silico models of aerosol delivery to the respiratory tract - development and applications. Adv Drug Deliv Rev 2012; 64:296-311. [PMID: 21640772 PMCID: PMC3258464 DOI: 10.1016/j.addr.2011.05.009] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/12/2011] [Accepted: 05/19/2011] [Indexed: 10/18/2022]
Abstract
This review discusses the application of computational models to simulate the transport and deposition of inhaled pharmaceutical aerosols from the site of particle or droplet formation to deposition within the respiratory tract. Traditional one-dimensional (1-D) whole-lung models are discussed briefly followed by a more in-depth review of three-dimensional (3-D) computational fluid dynamics (CFD) simulations. The review of CFD models is organized into sections covering transport and deposition within the inhaler device, the extrathoracic (oral and nasal) region, conducting airways, and alveolar space. For each section, a general review of significant contributions and advancements in the area of simulating pharmaceutical aerosols is provided followed by a more in-depth application or case study that highlights the challenges, utility, and benefits of in silico models. Specific applications presented include the optimization of an existing spray inhaler, development of charge-targeted delivery, specification of conditions for optimal nasal delivery, analysis of a new condensational delivery approach, and an evaluation of targeted delivery using magnetic aerosols. The review concludes with recommendations on the need for more refined model validations, use of a concurrent experimental and CFD approach for developing aerosol delivery systems, and development of a stochastic individual path (SIP) model of aerosol transport and deposition throughout the respiratory tract.
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Affiliation(s)
- P Worth Longest
- Department of Mechanical Engineering, Virginia Commonwealth University, Richmond, United States.
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Dhand R. Aerosol therapy in patients receiving noninvasive positive pressure ventilation. J Aerosol Med Pulm Drug Deliv 2011; 25:63-78. [PMID: 22191396 DOI: 10.1089/jamp.2011.0929] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In selected patients, noninvasive positive pressure ventilation (NIPPV) with a facemask is now commonly employed as the first choice for providing mechanical ventilation in the intensive care unit (ICU). Aerosol therapy for treatment of acute or acute-on-chronic respiratory failure in this setting may be delivered by pressurized metered-dose inhaler (pMDI) with a chamber spacer and facemask or nebulizer and facemask. This article reviews the host of factors influencing aerosol delivery with these devices during NIPPV. These factors include (1) the type of ventilator, (2) mode of ventilation, (3) circuit conditions, (4) type of interface, (5) type of aerosol generator, (6) drug-related factors, (7) breathing parameters, and (8) patient-related factors. Despite the impediments to efficient aerosol delivery because of continuous gas flow, high inspiratory flow rates, air leaks, circuit humidity, and patient-ventilator asynchrony, significant therapeutic effects are achieved after inhaled bronchodilator administration to patients with asthma and chronic obstructive pulmonary disease. Similarly to invasive mechanical ventilation, careful attention to the technique of drug administration is required to optimize therapeutic effects of inhaled therapies during NIPPV. Assessment of the patient's ability to tolerate a facemask, the level of respiratory distress, hemodynamic status, and synchronization of aerosol generation with inspiratory airflow are important factors contributing to the success of aerosol delivery during NIPPV. Further research into novel delivery methods, such as the use of NIPPV with nasal cannulae, could enhance the efficiency, ease of use, and reproducibility of inhalation therapy during noninvasive ventilation.
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Affiliation(s)
- Rajiv Dhand
- Division of Pulmonary, Critical Care, and Environmental Medicine, Department of Internal Medicine, University of Missouri, Columbia, Missouri 65212, USA.
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Longest PW, Hindle M. Condensational growth of combination drug-excipient submicrometer particles for targeted high efficiency pulmonary delivery: comparison of CFD predictions with experimental results. Pharm Res 2011; 29:707-21. [PMID: 21948458 DOI: 10.1007/s11095-011-0596-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/14/2011] [Indexed: 11/27/2022]
Abstract
PURPOSE The objective of this study was to investigate the hygroscopic growth of combination drug and excipient submicrometer aerosols for respiratory drug delivery using in vitro experiments and a newly developed computational fluid dynamics (CFD) model. METHODS Submicrometer combination drug and excipient particles were generated experimentally using both the capillary aerosol generator and the Respimat inhaler. Aerosol hygroscopic growth was evaluated in vitro and with CFD in a coiled tube geometry designed to provide residence times and thermodynamic conditions consistent with the airways. RESULTS The in vitro results and CFD predictions both indicated that the initially submicrometer particles increased in mean size to a range of 1.6-2.5 μm for the 50:50 combination of a non-hygroscopic drug (budesonide) and different hygroscopic excipients. CFD results matched the in vitro predictions to within 10% and highlighted gradual and steady size increase of the droplets, which will be effective for minimizing extrathoracic deposition and producing deposition deep within the respiratory tract. CONCLUSIONS Enhanced excipient growth (EEG) appears to provide an effective technique to increase pharmaceutical aerosol size, and the developed CFD model will provide a powerful design tool for optimizing this technique to produce high efficiency pulmonary delivery.
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