1
|
Darquenne C, Theilmann RJ, Rivoalen I, DeYoung PN, Orr JE, Malhotra A, Hicks CB, Owens RL. Upper airway imaging and function in obstructive sleep apnea in people with and without HIV. J Appl Physiol (1985) 2024; 136:313-321. [PMID: 38095015 DOI: 10.1152/japplphysiol.00750.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 11/29/2023] [Accepted: 12/12/2023] [Indexed: 12/22/2023] Open
Abstract
Obstructive sleep apnea (OSA) is common in people living with human immunodeficiency virus (HIV) (PLWH), but the underlying mechanisms are unclear. With improved long-term survival among PLWH, aging and obesity are increasingly prevalent in this population. These are also strong risk factors for the development of obstructive sleep apnea. We used magnetic resonance imaging (MRI) to measure upper airway (UA) anatomy and tongue fat content in PLWH with OSA (PLWH + OSA, n = 9) and in age-, sex-, and body mass index (BMI)-matched OSA controls (OSA, n = 11). We also quantified change in UA dimension during tidal breathing (during wakefulness and natural sleep) at four anatomical levels from the hard palate to the epiglottis along with synchronous MRI-compatible electroencephalogram and nasal flow measurements. All participants underwent on a separate night a baseline polysomnogram to assess OSA severity and an additional overnight physiological sleep study to measure OSA traits. We found no difference between the PLWH + OSA and the OSA control group in UA volume [PLWH + OSA: 12.8 mL (10.1-17.0), OSA: 14.0 mL (13.3-17.9), median (IQR)] or tongue volume [PLWH + OSA: 140.2 mL (125.1-156.9), OSA: 132.4 mL (126.8-154.7)] and a smaller tongue fat content in PLWH + OSA [11.2% (10.2-12.4)] than in the OSA controls [14.8% (13.2-15.5), P = 0.046]. There was no difference in the dynamic behavior of the UA between the two groups. When pooled together, both static and dynamic imaging metrics could be correlated with measures of UA mechanical properties. Our data suggest similar underlying UA physiology in OSA in subjects with and without HIV.NEW & NOTEWORTHY Obstructive sleep apnea is common in people living with human immunodeficiency virus (HIV), but the underlying mechanisms are unclear. We did not find differences in upper airway morphology using magnetic resonance imaging (MRI) during wake and natural sleep between people living with HIV (PLWH) with obstructive sleep apnea (OSA) and age, gender, and body mass index (BMI)-matched people with OSA but without HIV. Nor were there differences in tongue volume or changes in airway size during inspiration and expiration. MRI-derived anatomy was correlated with measures of airway collapse.
Collapse
Affiliation(s)
- Chantal Darquenne
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, California, United States
| | - Rebecca J Theilmann
- Department of Radiology, University of California, San Diego, California, United States
| | - Ines Rivoalen
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, California, United States
| | - Pamela N DeYoung
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, California, United States
| | - Jeremy E Orr
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, California, United States
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, California, United States
| | - Charles B Hicks
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, California, United States
| | - Robert L Owens
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, California, United States
| |
Collapse
|
2
|
Kuprat AP, Price O, Asgharian B, Singh RK, Colby S, Yugulis K, Corley RA, Darquenne C. Automated bidirectional coupling of multiscale models of aerosol dosimetry: validation with subject-specific deposition data. J Aerosol Sci 2023; 174:106233. [PMID: 37637507 PMCID: PMC10448711 DOI: 10.1016/j.jaerosci.2023.106233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/29/2023]
Abstract
Assessing the toxicity of airborne particulate matter or the efficacy of inhaled drug depends upon accurate estimates of deposited fraction of inhaled materials. In silico approaches can provide important insights into site- or airway-specific deposition of inhaled aerosols in the respiratory system. In this study, we improved on our recently developed 3D/1D model that simulate aerosol transport and deposition in the whole lung over multiple breath cycles (J. Aerosol Sci 151:105647). A subject-specific multiscale lung model of a healthy male subject using computational fluid-particle dynamics (CFPD) in a 3D model of the oral cavity through the large bronchial airways entering each lobe was bidirectionally coupled with a recently improved Multiple Path Particle Dosimetry (MPPD) model to predict aerosol deposition over the entire respiratory tract over multiple breaths for four conditions matching experimental aerosol exposures in the same subject from which the model was developed. These include two particle sizes (1 and 2.9 μm) and two subject-specific breathing rates of ~300 ml/s (slow breathing) and ~750 ml/s (fast breathing) at a target tidal volume of 1 L. In silico predictions of retained fraction were 0.31 and 0.29 for 1 μm and 0.66 and 0.62 for 2.9 μm during slow and fast breathing, respectively, and compared well with experimental data (1 μm: 0.31±0.01 (slow) and 0.27±0.01 (fast), 2.9 μm: 0.63±0.03 (slow) and 0.68±0.02 (fast)). These results provide a great deal of confidence in the validity and reliability of our approach.
Collapse
Affiliation(s)
- A P Kuprat
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - O Price
- Applied Research Associates, Arlington Division, Raleigh, NC, USA
| | - B Asgharian
- Applied Research Associates, Arlington Division, Raleigh, NC, USA
| | - R K Singh
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - S Colby
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - K Yugulis
- Battelle Memorial Institute, Columbus, OH, USA
| | - R A Corley
- Greek Creek Toxicokinetics Consulting, LLC, Boise, ID, USA
| | - C Darquenne
- Department of Medicine, University of California, San Diego, CA, USA
| |
Collapse
|
3
|
Thompson RB, Darquenne C. Magnetic Resonance Imaging of Aerosol Deposition. J Aerosol Med Pulm Drug Deliv 2023; 36:228-234. [PMID: 37523222 DOI: 10.1089/jamp.2023.29087.rbt] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023] Open
Abstract
Nuclear magnetic resonance imaging (MRI) uses non-ionizing radiation and offers a host of contrast mechanisms with the potential to quantify aerosol deposition. This chapter introduces the physics of MRI, its use in lung imaging, and more specifically, the methods that are used for the detection of regional distributions of inhaled particles. The most common implementation of MRI is based on imaging of hydrogen atoms (1H) in water. The regional deposition of aerosol particles can be measured by the perturbation of the acquired 1H signals via labeling of the aerosol with contrast agents. Existing in vitro human and in vivo animal model measurements of regional aerosol deposition in the respiratory tract are described, demonstrating the capability of MRI to assess aerosol deposition in the lung.
Collapse
Affiliation(s)
- Richard B Thompson
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Chantal Darquenne
- Department of Medicine, University of California San Diego, San Diego, California, USA
| |
Collapse
|
4
|
Everett C, Darquenne C, Niles R, Seifert M, Tumminello PR, Slade JH. Aerosols, airflow, and more: examining the interaction of speech and the physical environment. Front Psychol 2023; 14:1184054. [PMID: 37255523 PMCID: PMC10225543 DOI: 10.3389/fpsyg.2023.1184054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 04/28/2023] [Indexed: 06/01/2023] Open
Abstract
We describe ongoing efforts to better understand the interaction of spoken languages and their physical environments. We begin by briefly surveying research suggesting that languages evolve in ways that are influenced by the physical characteristics of their environments, however the primary focus is on the converse issue: how speech affects the physical environment. We discuss the speech-based production of airflow and aerosol particles that are buoyant in ambient air, based on some of the results in the literature. Most critically, we demonstrate a novel method used to capture aerosol, airflow, and acoustic data simultaneously. This method captures airflow data via a pneumotachograph and aerosol data via an electrical particle impactor. The data are collected underneath a laminar flow hood while participants breathe pure air, thereby eliminating background aerosol particles and isolating those produced during speech. Given the capabilities of the electrical particle impactor, which has not previously been used to analyze speech-based aerosols, the method allows for the detection of aerosol particles at temporal and physical resolutions exceeding those evident in the literature, even enabling the isolation of the role of individual sound types in the production of aerosols. The aerosols detected via this method range in size from 70 nanometers to 10 micrometers in diameter. Such aerosol particles are capable of hosting airborne pathogens. We discuss how this approach could ultimately yield data that are relevant to airborne disease transmission and offer preliminary results that illustrate such relevance. The method described can help uncover the actual articulatory gestures that generate aerosol emissions, as exemplified here through a discussion focused on plosive aspiration and vocal cord vibration. The results we describe illustrate in new ways the unseen and unheard ways in which spoken languages interact with their physical environments.
Collapse
Affiliation(s)
- Caleb Everett
- Departments of Anthropology and Psychology, University of Miami, Coral Gables, FL, United States
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Renee Niles
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| | - Marva Seifert
- Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Paul R Tumminello
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| | - Jonathan H Slade
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| |
Collapse
|
5
|
Borojeni AAT, Gu W, Asgharian B, Price O, Kuprat AP, Singh RK, Colby S, Corley RA, Darquenne C. In Silico Quantification of Intersubject Variability on Aerosol Deposition in the Oral Airway. Pharmaceutics 2023; 15:pharmaceutics15010160. [PMID: 36678786 PMCID: PMC9860768 DOI: 10.3390/pharmaceutics15010160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/23/2022] [Accepted: 12/27/2022] [Indexed: 01/05/2023] Open
Abstract
The extrathoracic oral airway is not only a major mechanical barrier for pharmaceutical aerosols to reach the lung but also a major source of variability in lung deposition. Using computational fluid dynamics, deposition of 1−30 µm particles was predicted in 11 CT-based models of the oral airways of adults. Simulations were performed for mouth breathing during both inspiration and expiration at two steady-state flow rates representative of resting/nebulizer use (18 L/min) and of dry powder inhaler (DPI) use (45 L/min). Consistent with previous in vitro studies, there was a large intersubject variability in oral deposition. For an optimal size distribution of 1−5 µm for pharmaceutical aerosols, our data suggest that >75% of the inhaled aerosol is delivered to the intrathoracic lungs in most subjects when using a nebulizer but only in about half the subjects when using a DPI. There was no significant difference in oral deposition efficiency between inspiration and expiration, unlike subregional deposition, which shows significantly different patterns between the two breathing phases. These results highlight the need for incorporating a morphological variation of the upper airway in predictive models of aerosol deposition for accurate predictions of particle dosimetry in the intrathoracic region of the lung.
Collapse
Affiliation(s)
| | - Wanjun Gu
- Department of Medicine, University of California, San Diego, CA 92093-0623, USA
| | - Bahman Asgharian
- Applied Research Associates, Arlington Division, Raleigh, NC 27615-2963, USA
| | - Owen Price
- Applied Research Associates, Arlington Division, Raleigh, NC 27615-2963, USA
| | | | - Rajesh K. Singh
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Sean Colby
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Richard A. Corley
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
- Greek Creek Toxicokinetics Consulting, LLC, Boise, ID 83714, USA
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, CA 92093-0623, USA
- Correspondence:
| |
Collapse
|
6
|
Asgharian B, Price O, Borojeni A, Kuprat A, Colby S, Singh R, Gu W, Corley R, Darquenne C. Influence of alveolar mixing and multiple breaths of aerosol intake on particle deposition in the human lungs. J Aerosol Sci 2022; 166:106050. [PMID: 36405567 PMCID: PMC9671400 DOI: 10.1016/j.jaerosci.2022.106050] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Predictive dosimetry models play an important role in assessing health effect of inhaled particulate matter and in optimizing delivery of inhaled pharmaceutical aerosols. In this study, the commonly used 1D Multiple-Path Particle Dosimetry model (MPPD) was improved by including a mechanistically based model component for alveolar mixing of particles and by extending the model capabilities to account for multiple breaths of aerosol intake. These modifications increased the retained fraction of particles and consequently particle deposition predictions in the deep lung during tidal breathing. Comparison with an existing dataset (J. Aerosol Sci., 99:27-39, 2016) obtained under two breathing conditions referred to as slow and fast breathing showed significant differences in 1 μm particle deposition between predictions based on subject-specific breathing patterns and lung volume (slow: 30 ± 1%, fast: 21 ± 1%, (average ± standard deviation), N = 7) and measurements (slow: 43 ± 9%, fast: 30 ± 5%) when the prior version of MPPD (single breath and no mixing, J. Aerosol Sci., 151:105647, 2021) was used. Adding a mixing model and multiple breaths moved the predictions (slow: 34 ± 2%, fast:25 ± 2%) closer to the range of deposition measurements. For 2.9 μm particles, predictions from both the original (slow: 70 ± 2%, fast: 57 ± 2%) and the revised MPPD model (slow: 71 ± 2%, fast: 59 ± 3%) compared well with experiments (slow: 67 ± 8%, fast: 58 ± 10%). This was expected as suspended fraction of 2.9 μm particles was small and thus the addition of alveolar mixing and multi breath capability only slightly increased the retained fraction for particles of this size and greater. The revised 1D model improves dose predictions in the deep lung and support human risk assessment from exposure to airborne particles.
Collapse
Affiliation(s)
- B. Asgharian
- Applied Research Associates, Arlington Division, Raleigh, NC, USA
| | - O. Price
- Applied Research Associates, Arlington Division, Raleigh, NC, USA
| | - A.A.T. Borojeni
- Department of Medicine, University of California, San Diego, CA, USA
| | - A.P. Kuprat
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - S. Colby
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - R.K. Singh
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - W. Gu
- Department of Medicine, University of California, San Diego, CA, USA
| | - R.A. Corley
- Pacific Northwest National Laboratory, Richland, WA, USA
- Greek Creek Toxicokinetics Consulting, LLC, Boise, ID, USA
| | - C. Darquenne
- Department of Medicine, University of California, San Diego, CA, USA
| |
Collapse
|
7
|
Darquenne C, Borojeni AA, Colebank MJ, Forest MG, Madas BG, Tawhai M, Jiang Y. Aerosol Transport Modeling: The Key Link Between Lung Infections of Individuals and Populations. Front Physiol 2022; 13:923945. [PMID: 35795643 PMCID: PMC9251577 DOI: 10.3389/fphys.2022.923945] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 05/24/2022] [Indexed: 12/18/2022] Open
Abstract
The recent COVID-19 pandemic has propelled the field of aerosol science to the forefront, particularly the central role of virus-laden respiratory droplets and aerosols. The pandemic has also highlighted the critical need, and value for, an information bridge between epidemiological models (that inform policymakers to develop public health responses) and within-host models (that inform the public and health care providers how individuals develop respiratory infections). Here, we review existing data and models of generation of respiratory droplets and aerosols, their exhalation and inhalation, and the fate of infectious droplet transport and deposition throughout the respiratory tract. We then articulate how aerosol transport modeling can serve as a bridge between and guide calibration of within-host and epidemiological models, forming a comprehensive tool to formulate and test hypotheses about respiratory tract exposure and infection within and between individuals.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, San Diego, CA, United States
- *Correspondence: Chantal Darquenne,
| | - Azadeh A.T. Borojeni
- Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Mitchel J. Colebank
- Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center and Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States
| | - M. Gregory Forest
- Departments of Mathematics, Applied Physical Sciences, and Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Balázs G. Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, United States
| |
Collapse
|
8
|
Darquenne C, Theilmann RJ, Fine JM, Verbanck SAB. Nitrogen-based lung clearance index: a valid physiological biomarker for the clinic. J Appl Physiol (1985) 2022; 132:1290-1296. [PMID: 35446597 PMCID: PMC9126222 DOI: 10.1152/japplphysiol.00511.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Multiple breath washout (MBW) testing is increasingly used as a physiological measurement in the clinic, due in part to the availability of commercial equipment and reference values for MBW indices. Commercial N2 washout devices are usually based on indirect measurement of N2 concentration (CN2), by directly measuring either molar mass and O2 and CO2, or molar mass and CO2. We aim to elucidate the role of two potential pitfalls associated with N2-MBW testing that could override its physiological content: indirect N2 measurement and blood-solubility of N2. We performed MBW in 12 healthy adult subjects using a commercial device (MBWindirect) with simultaneous direct gas concentration measurements by mass spectrometry (MBWdirect) and compared CN2 between MBWdirect and MBWindirect. We also measured argon concentration during the same washouts to verify the maximal effect gas solubility can have on N2-based functional residual capacity (FRC) and lung clearance index (LCI). Continuous N2 concentration traces were very similar for MBWindirect and MBWdirect, resulting in comparable breath-by-breath washout plots of expired concentration and in no significant differences in FRCN2, LCIN2, Scond, and Sacin between the two methods. Argon washouts were slightly slower than N2 washouts, as expected for a less diffusive and more soluble gas. Finally, comparison between LCIN2 and LCIAr indicates that the maximum impact from blood-tissue represents less than half a LCI unit in normal subjects. In conclusion, we have demonstrated by direct measurement of N2 and twice as soluble argon, that indirect N2 measurement can be safely used as a meaningful physiological measurement.NEW & NOTEWORTHY The physiological content of N2 multibreath washout testing has been questioned due to N2 indirect measurement accuracy and N2 blood solubility. With direct measurement of N2 and twice as soluble argon, we show that these effects are largely outweighed by ease of use.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, California
| | | | - Janelle M Fine
- Department of Medicine, University of California, San Diego, California
| | - Sylvia A B Verbanck
- Respiratory Division, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| |
Collapse
|
9
|
Orr JE, Edwards BA, Schmickl CN, Karris M, DeYoung PN, Darquenne C, Theilmann R, Jain S, Malhotra A, Hicks CB, Owens RL. Pathogenesis of obstructive sleep apnea in people living with HIV. J Appl Physiol (1985) 2021; 131:1671-1678. [PMID: 34672765 PMCID: PMC8714978 DOI: 10.1152/japplphysiol.00591.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Obstructive sleep apnea (OSA) is highly prevalent in people living with human immunodeficiency virus (HIV) (PLWH), and it might contribute to frequently reported symptoms and comorbidities. Traditional risk factors for OSA are often absent in PLWH, suggesting that HIV or HIV medications might predispose to OSA. Therefore, we measured the anatomical and nonanatomical traits important for OSA pathogenesis in those with and without HIV. We recruited virally suppressed PLWH who had been previously diagnosed with OSA (PLWH + OSA) adherent to positive airway pressure (PAP) therapy, along with age-, sex-, and body mass index (BMI)-matched OSA controls. All participants underwent a baseline polysomnogram to assess OSA severity and a second overnight research sleep study during which the airway pressure was adjusted slowly or rapidly to measure the OSA traits. Seventeen PLWH + OSA and 17 OSA control participants were studied [median age = 58 (IQR = 54-65) yr, BMI = 30.7 (28.4-31.8) kg/m2, apnea-hypopnea index = 46 (24-74)/h]. The groups were similar, although PLWH + OSA demonstrated greater sleepiness (despite PAP) and worse sleep efficiency on baseline polysomnography. On physiological testing during sleep, there were no statistically significant differences in OSA traits (including Veupnea, Varousal, Vpassive, Vactive, and loop gain) between PLWH + OSA and OSA controls, using mixed-effects modeling to account for age, sex, and BMI and incorporating each repeated measurement (range = 72-334 measures/trait). Our data suggest that well-treated HIV does not substantially impact the pathogenesis of OSA. Given similar underlying physiology, existing available therapeutic approaches are likely to be adequate to manage OSA in PLWH, which might improve symptoms and comorbidities.NEW & NOTEWORTHY Clinical data suggest an increased risk of obstructive sleep apnea (OSA) in people living with HIV (PLWH), while OSA might account for chronic health issues in this population. We characterized the anatomical and nonanatomical OSA traits in PLWH + OSA compared with OSA controls, using detailed physiological measurements obtained during sleep. Our data suggest against a major impact of HIV on OSA pathogenesis. Available OSA management strategies should be effective to address this potentially important comorbidity in PLWH.
Collapse
Affiliation(s)
- Jeremy E Orr
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, California
| | - Bradley A Edwards
- Sleep and Circadian Medicine Laboratory, Department of Physiology, Biomedicine Discovery Institute, Monash University, Melbourne, Australia.,Turner Institute for Brain and Mental Health, Monash University, Melbourne, Australia
| | - Christopher N Schmickl
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, California
| | - Maile Karris
- Division of Infectious Disease, University of California San Diego, San Diego, California
| | - Pamela N DeYoung
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, California
| | - Chantal Darquenne
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, California
| | - Rebecca Theilmann
- Department of Radiology, University of California San Diego, San Diego, California
| | - Sonia Jain
- Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, San Diego, California
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, California
| | - Charles B Hicks
- Division of Infectious Disease, University of California San Diego, San Diego, California
| | - Robert L Owens
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, San Diego, California
| |
Collapse
|
10
|
Affiliation(s)
- Alexander Horsley
- 1Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Chantal Darquenne
- 2Department of Medicine, University of California, San Diego, La Jolla, California
| |
Collapse
|
11
|
Stylemans D, Darquenne C, Schuermans D, Verbanck S, Vanderhelst E. Peripheral lung effect of elexacaftor/tezacaftor/ivacaftor in adult cystic fibrosis. J Cyst Fibros 2021; 21:160-163. [PMID: 33832855 DOI: 10.1016/j.jcf.2021.03.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 11/18/2022]
Abstract
Despite being an important patient group, adult cystic fibrosis patients with an FEV1 below 40%predicted have been excluded from clinical trials with elexacaftor/tezacaftor/ivacaftor. We conducted a real-life 3 months follow-up study in 14 adult CF patients (median FEV1 34%predicted) demonstrating significant treatment effects in terms of FEV1 (an increase of 12%predicted at 4 weeks, remaining stable thereafter). Corresponding decreases in lung clearance index LCI (by 31%predicted, down from baseline 247%predicted) and ventilation heterogeneity in the acinar compartment (Sacin) (by 411%predicted, down from baseline 798%predicted) suggest a distinct peripheral lung effect. One patient had intermittent treatment interruptions because of drug-induced liver injury. Our real-life data confirm that treatment with elexacaftor/tezacaftor/ivacaftor is effective in severely obstructive patients, and this is the first study to show time evolution of ventilation distribution improvement, pointing to the peripheral lung as the main site of treatment effect.
Collapse
Affiliation(s)
- Dimitri Stylemans
- Respiratory Division, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090 Brussels, Belgium.
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, CA 92093-0623, USA
| | - Daniël Schuermans
- Respiratory Division, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090 Brussels, Belgium
| | - Sylvia Verbanck
- Respiratory Division, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090 Brussels, Belgium
| | - Eef Vanderhelst
- Respiratory Division, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090 Brussels, Belgium
| |
Collapse
|
12
|
Abstract
Laboratory animals are often used to derive health risk from environmental exposure or to assess the therapeutic effect of a drug delivered by inhaled therapy. Knowledge of the in-situ distribution of deposited particles on airway and alveolar surfaces is essential in any assessment of these effects. A unique database including both high-resolution lung anatomy and deposition data in four strains of laboratory mice have been recently made publicly available to the research community (https://doi.org/10.25820/9arg-9w56). Using these data, we investigated the effect of particle size on the distribution of deposited particles at the lobar and near-acini level. Analysis was performed on a total of 33 mice where 3, 16 and 14 animals were exposed to 0.5μm, 1μm and 2μm particles, respectively. Ratio of normalized deposition to normalized volume was calculated for each lobe (DV lobe ). At the near-acini level, the skew and standard deviation of the frequency distribution of particle deposition were calculated. Significant deviation above 1 was found for DV ratio in the cranial lobe (DV Cranial ). DV Middle , DV Caudal and DV Accessory were all significantly <1 and lower than DV left (p<0.01). At the near-acini level, skew and standard deviation were positively correlated with particle size and the presence of hot spots (high deposition) were mainly found in the apical region of the lung. These results highlight the uneven distribution of deposited particles in the mouse lung. Thus, depending on the lung sample location, individual analysis to determine overall deposition may either underestimate or overestimate total lung burden, at least for micron-sized particles.
Collapse
Affiliation(s)
- W. Gu
- Department of Medicine, University of California, San Diego, USA
| | - C. Darquenne
- Department of Medicine, University of California, San Diego, USA
| |
Collapse
|
13
|
Kuprat AP, Jalali M, Jan T, Corley RA, Asgharian B, Price O, Singh RK, Colby S, Darquenne C. Efficient bi-directional coupling of 3D Computational Fluid-Particle Dynamics and 1D Multiple Path Particle Dosimetry lung models for multiscale modeling of aerosol dosimetry. J Aerosol Sci 2021; 151:105647. [PMID: 34024935 PMCID: PMC8136587 DOI: 10.1016/j.jaerosci.2020.105647] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The development of predictive aerosol dosimetry models has been a major focus of environmental toxicology and pharmaceutical health research for decades. One-dimensional (1D) models successfully predict overall deposition averages but fail to accurately predict local deposition. Computational fluid-particle dynamics (CFPD) models provide site-specific predictions but at a computational cost that prohibits whole lung predictions. Thus, there is a need for developing multiscale strategies to provide a realistic subject-specific picture of the fate of inhaled aerosol in the lungs. CT-based 3D/CFPD models of the large airways were bidirectionally coupled with individualized 1D Navier-Stokes airflow and particle transport based upon the widely used Multiple Path Particle Dosimetry Model (MPPD). Distribution of airflows among lobes was adjusted by measured lobar volume changes observed in CT images between FRC and FRC + 1.5 L. As a test of the effectiveness of the coupling procedures, deposition modeling of previous 1 μm aerosol exposure studies was performed. The complete coupled model was run for 3 breaths, with the computation-intense portion being the 3D CFPD Lagrangian particle tracking calculation. The average deposition per breath was 11% in the combined multiscale model with site-specific doses available in the CFPD portion of the model and airway- or region-specific deposition available for the MPPD portion. In conclusion, the key methods developed in this study enable predictions of ventilation heterogeneities and aerosol deposition across the lungs that are not captured by 3D or 1D models alone. These methods can be used as the foundation for multi-scale modeling of the full respiratory system.
Collapse
Affiliation(s)
- A P Kuprat
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - M Jalali
- Department of Medicine, University of California, San Diego, CA, USA
| | - T Jan
- Department of Medicine, University of California, San Diego, CA, USA
| | - R A Corley
- Pacific Northwest National Laboratory, Richland, WA, USA
- Greek Creek Toxicokinetics Consulting, LLC, Boise, ID, USA
| | - B Asgharian
- Applied Research Associates, Arlington Division, Raleigh, NC, USA
| | - O Price
- Applied Research Associates, Arlington Division, Raleigh, NC, USA
| | - R K Singh
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - S Colby
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - C Darquenne
- Department of Medicine, University of California, San Diego, CA, USA
| |
Collapse
|
14
|
Fink JB, Ehrmann S, Li J, Dailey P, McKiernan P, Darquenne C, Martin AR, Rothen-Rutishauser B, Kuehl PJ, Häussermann S, MacLoughlin R, Smaldone GC, Muellinger B, Corcoran TE, Dhand R. Reducing Aerosol-Related Risk of Transmission in the Era of COVID-19: An Interim Guidance Endorsed by the International Society of Aerosols in Medicine. J Aerosol Med Pulm Drug Deliv 2020; 33:300-304. [PMID: 32783675 PMCID: PMC7757542 DOI: 10.1089/jamp.2020.1615] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
National and international guidelines recommend droplet/airborne transmission and contact precautions for those caring for coronavirus disease 2019 (COVID-19) patients in ambulatory and acute care settings. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, an acute respiratory infectious agent, is primarily transmitted between people through respiratory droplets and contact routes. A recognized key to transmission of COVID-19, and droplet infections generally, is the dispersion of bioaerosols from the patient. Increased risk of transmission has been associated with aerosol generating procedures that include endotracheal intubation, bronchoscopy, open suctioning, administration of nebulized treatment, manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, noninvasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation. The knowledge that COVID-19 subjects can be asymptomatic and still shed virus, producing infectious droplets during breathing, suggests that health care workers (HCWs) should assume every patient is potentially infectious during this pandemic. Taking actions to reduce risk of transmission to HCWs is, therefore, a vital consideration for safe delivery of all medical aerosols. Guidelines for use of personal protective equipment (glove, gowns, masks, shield, and/or powered air purifying respiratory) during high-risk procedures are essential and should be considered for use with lower risk procedures such as administration of uncontaminated medical aerosols. Bioaerosols generated by infected patients are a major source of transmission for SARS CoV-2, and other infectious agents. In contrast, therapeutic aerosols do not add to the risk of disease transmission unless contaminated by patients or HCWs.
Collapse
Affiliation(s)
- James B Fink
- Aerogen Pharma Corp., San Mateo, California, USA.,Division of Respiratory Care, Department of Cardiopulmonary Sciences, Rush University Medical Center, Chicago, Illinois, USA
| | - Stephan Ehrmann
- CHRU Tours, Médecine Intensive Réanimation, CIC INSERM 1415, CRICS-TriggerSep Research Network, Tours, France.,INSERM, Centre d'étude des Pathologies Respiratoires, U1100, Université de Tours, Tours, France
| | - Jie Li
- Division of Respiratory Care, Department of Cardiopulmonary Sciences, Rush University Medical Center, Chicago, Illinois, USA
| | | | | | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, California, USA
| | - Andrew R Martin
- Mechanical Engineering, University of Alberta, Edmonton, Canada
| | | | | | | | - Ronan MacLoughlin
- Aerogen Limited, Galway, Ireland.,School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons, Dublin, Ireland.,School of Pharmacy and Pharmaceutical Sciences, Trinity College, Dublin, Ireland
| | - Gerald C Smaldone
- Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, State University of New York at Stony Brook, Stony Brook, New York, USA
| | | | - Timothy E Corcoran
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Rajiv Dhand
- Department of Medicine, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, Tennessee, USA
| |
Collapse
|
15
|
Mitchell JP, Berlinski A, Canisius S, Cipolla D, Dolovich MB, Gonda I, Hochhaus G, Kadrichu N, Lyapustina S, Mansour HM, Darquenne C, Clark AR, Newhouse M, Ehrmann S, Humphries R, Boushey H. Urgent Appeal from International Society for Aerosols in Medicine (ISAM) During COVID-19: Clinical Decision Makers and Governmental Agencies Should Consider the Inhaled Route of Administration: A Statement from the ISAM Regulatory and Standardization Issues Networking Group. J Aerosol Med Pulm Drug Deliv 2020; 33:235-238. [DOI: 10.1089/jamp.2020.1622] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Jolyon P. Mitchell
- Jolyon Mitchell Inhaler Consultancy Services, Inc., London, Ontario, Canada
| | - Ariel Berlinski
- Pulmonology Division, Department of Pediatrics, University of Arkansas for Medical Sciences, College of Medicine, Little Rock, Arkansas, USA
| | | | | | - Myrna B. Dolovich
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Igor Gonda
- Respidex LLC, Dennis, Massachusetts, USA
| | - Guenther Hochhaus
- College of Pharmacy, University of Florida, Gainesville, Florida, USA
| | - Nani Kadrichu
- Inspired—Pulmonary Solutions LLC, San Carlos, California, USA
| | | | - Heidi M. Mansour
- College of Pharmacy, College of Medicine and The University of Arizona-Tucson, Tucson, Arizona, USA
| | | | - Andy R. Clark
- Aerogen Pharma Corporation, San Mateo, California, USA
| | - Michael Newhouse
- St. Joseph's Hospital Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
- Firestone Institute for Respiratory Health, McMaster University, Hamilton, Ontario, Canada
| | - Stephan Ehrmann
- Centre Hospitalier Régional et Universitaire de Tours, Médecine Intensive Réanimation, Tours, France
| | | | - Homer Boushey
- School of Medicine, Universtiy of California San Francisco, San Francisco, California, USA
| |
Collapse
|
16
|
Abstract
The distribution of particles sizes within an aerosol is essential information for understanding the behavior of that aerosol. The number of particles within certain size ranges is given by distributions specified by a count distribution if referring to number of particles, or a mass distribution if referring to particle mass. The cumulative number, or mass, of particles less than a certain diameter is determined by integrating the relevant distribution, which allows definition of median diameters. The mass median diameter is a commonly specified diameter. For log-normal distributions, the spread of the distribution is given by the geometric standard deviation. Although particle size distributions of actual aerosols are discrete by nature, the use of continuous functions to describe them is a useful conceptual tool.
Collapse
Affiliation(s)
- Warren H Finlay
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego; La Jolla, California, USA
| |
Collapse
|
17
|
Abstract
The success of inhalation therapy is not only dependent upon the pharmacology of the drugs being inhaled but also upon the site and extent of deposition in the respiratory tract. Similarly, the toxicity of environmental and industrial particulate matter is affected not only by the nature of the dust but also by the amount and spatial distribution of deposited particles in the lung. Aerosol deposition is primarily governed by the mechanisms of inertial impaction, gravitational sedimentation, Brownian diffusion, and, to a lesser extent, by turbulence, electrostatic precipitation, and interception. The relative contribution of these different mechanisms is a function of the physical characteristics of the particles, the lung structure, and the flow patterns. Large particles (>5 μm) tend to deposit mainly in the upper and large airways, limiting the amount of aerosols that can be delivered to the lung. Small particles (<2 μm) deposit mainly in the alveolar region, whereas particles in the size range 2-5 μm deposit preferentially in the central and small airways.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego; La Jolla, California, USA
| |
Collapse
|
18
|
Ehrmann S, Schmid O, Darquenne C, Rothen-Rutishauser B, Sznitman J, Yang L, Barosova H, Vecellio L, Mitchell J, Heuze-Vourc’h N. Innovative preclinical models for pulmonary drug delivery research. Expert Opin Drug Deliv 2020; 17:463-478. [PMID: 32057260 PMCID: PMC8083945 DOI: 10.1080/17425247.2020.1730807] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 02/11/2020] [Indexed: 02/08/2023]
Abstract
Introduction: Pulmonary drug delivery is a complex field of research combining physics which drive aerosol transport and deposition and biology which underpins efficacy and toxicity of inhaled drugs. A myriad of preclinical methods, ranging from in-silico to in-vitro, ex-vivo and in-vivo, can be implemented.Areas covered: The present review covers in-silico mathematical and computational fluid dynamics modelization of aerosol deposition, cascade impactor technology to estimated drug delivery and deposition, advanced in-vitro cell culture methods and associated aerosol exposure, lung-on-chip technology, ex-vivo modeling, in-vivo inhaled drug delivery, lung imaging, and longitudinal pharmacokinetic analysis.Expert opinion: No single preclinical model can be advocated; all methods are fundamentally complementary and should be implemented based on benefits and drawbacks to answer specific scientific questions. The overall best scientific strategy depends, among others, on the product under investigations, inhalation device design, disease of interest, clinical patient population, previous knowledge. Preclinical testing is not to be separated from clinical evaluation, as small proof-of-concept clinical studies or conversely large-scale clinical big data may inform preclinical testing. The extend of expertise required for such translational research is unlikely to be found in one single laboratory calling for the setup of multinational large-scale research consortiums.
Collapse
Affiliation(s)
- Stephan Ehrmann
- CHRU Tours, Médecine Intensive Réanimation, CIC INSERM 1415, CRICS-TriggerSep network, Tours France
- INSERM, Centre d’étude des pathologies respiratoires, U1100, Tours, France
- Université de Tours, Tours, France
| | - Otmar Schmid
- Comprehensive Pneumology Center (CPC-M), German Center for Lung Research (DZL), Max-Lebsche-Platz 31, 81377 Munich, Germany
- Institute of Lung Biology and Disease, Helmholtz Zentrum München – German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC0623A, La Jolla, CA 92093-0623, United States
| | | | - Josue Sznitman
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Julius Silver building, Office 246, Haifa 32000, Israel
| | - Lin Yang
- Comprehensive Pneumology Center (CPC-M), German Center for Lung Research (DZL), Max-Lebsche-Platz 31, 81377 Munich, Germany
- Institute of Lung Biology and Disease, Helmholtz Zentrum München – German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Hana Barosova
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg, Switzerland
| | - Laurent Vecellio
- INSERM, Centre d’étude des pathologies respiratoires, U1100, Tours, France
- Université de Tours, Tours, France
| | - Jolyon Mitchell
- Jolyon Mitchell Inhaler Consulting Services Inc., 1154 St. Anthony Road, London, Ontario, Canada, N6H 2R1
| | - Nathalie Heuze-Vourc’h
- INSERM, Centre d’étude des pathologies respiratoires, U1100, Tours, France
- Université de Tours, Tours, France
| |
Collapse
|
19
|
Darquenne C, Prisk GK. The Effect of Aging on Aerosol Bolus Deposition in the Healthy Adult Lung: A 19-Year Longitudinal Study. J Aerosol Med Pulm Drug Deliv 2019; 33:133-139. [PMID: 31613688 DOI: 10.1089/jamp.2019.1566] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: While it is recognized that peripheral lung structure and ventilation heterogeneity change with age, the effects of age on aerosol deposition in the healthy adult lung is largely unknown. Methods: A series of aerosol bolus inhalations were repeatedly performed in four healthy subjects over a period of 19 years (years = 0, 9, 15 and 19). For each series, a bolus of 1 μm particles was inhaled at penetration volumes (Vp) ranging from 200 to 1200 mL. Aerosol bolus deposition (DE), dispersion (H), and mode shift (MS) were calculated along with the rate of increase in these parameters with increasing Vp (slope-DE, slope-H, and slope-MS). Results: Slope-DE significantly increased from 0.040 ± 0.014 (mean ± standard deviation) at year 0 to 0.069 ± 0.007%/mL at year 19 (p = 0.02) with no significant difference in DE at shallow depth (Vp = 200 mL; 14% ± 4% at year 0 vs. 15% ± 7% at year 19, p = 0.25). There was no significant effect of age on either slope-H (0.44 ± 0.05 at year 0 vs. 0.47 ± 0.09 mL/mL at year 19, p = 0.6) or dispersion at shallow depth (192 ± 36 mL at year 0 vs. 220 ± 54 mL at year 19, p = 0.2). Slope-MS became significantly more negative with increasing age (-0.096 ± 0.044 at year 0 vs. -0.171 ± 0.027 mL/mL at year 19, p = 0.001) with no significant difference in MS at shallow depth (12 ± 10 at year 0 vs. 7 ± 15 mL at year 19, p = 0.3). Conclusions: These data suggest that (1) peripheral deposition increases with aging in the healthy lung, likely as a result of increasing closing volume with age; (2) alterations in the mechanical properties of healthy adult lungs with age occur uniformly; and (3) the significant increase in the magnitude of MS-slope with age is likely due to the concomitant increase in peripheral deposition and possible alterations in flow sequencing.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - G Kim Prisk
- Department of Medicine, University of California, San Diego, La Jolla, California
| |
Collapse
|
20
|
Geier ET, Theilmann RJ, Darquenne C, Prisk GK, Sá RC. Quantitative Mapping of Specific Ventilation in the Human Lung using Proton Magnetic Resonance Imaging and Oxygen as a Contrast Agent. J Vis Exp 2019. [PMID: 31233033 DOI: 10.3791/59579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Specific ventilation imaging (SVI) is a functional magnetic resonance imaging technique capable of quantifying specific ventilation - the ratio of the fresh gas entering a lung region divided by the region's end-expiratory volume - in the human lung, using only inhaled oxygen as a contrast agent. Regional quantification of specific ventilation has the potential to help identify areas of pathologic lung function. Oxygen in solution in tissue shortens the tissue's longitudinal relaxation time (T1), and thus a change in tissue oxygenation can be detected as a change in T1-weighted signal with an inversion recovery acquired image. Following an abrupt change between two concentrations of inspired oxygen, the rate at which lung tissue within a voxel equilibrates to a new steady-state reflects the rate at which resident gas is being replaced by inhaled gas. This rate is determined by specific ventilation. To elicit this sudden change in oxygenation, subjects alternately breathe 20-breath blocks of air (21% oxygen) and 100% oxygen while in the MRI scanner. A stepwise change in inspired oxygen fraction is achieved through use of a custom three-dimensional (3D)-printed flow bypass system with a manual switch during a short end-expiratory breath hold. To detect the corresponding change in T1, a global inversion pulse followed by a single shot fast spin echo sequence was used to acquire two-dimensional T1-weighted images in a 1.5 T MRI scanner, using an eight-element torso coil. Both single slice and multi-slice imaging are possible, with slightly different imaging parameters. Quantification of specific ventilation is achieved by correlating the time-course of signal intensity for each lung voxel with a library of simulated responses to the air/oxygen stimulus. SVI estimations of specific ventilation heterogeneity have been validated against multiple breath washout and proved to accurately determine the heterogeneity of the specific ventilation distribution.
Collapse
Affiliation(s)
- Eric T Geier
- Pulmonary Imaging Laboratory, Department of Medicine, University of California, San Diego
| | - Rebecca J Theilmann
- Pulmonary Imaging Laboratory, Department of Radiology, University of California, San Diego
| | - Chantal Darquenne
- Pulmonary Imaging Laboratory, Department of Medicine, University of California, San Diego
| | - G Kim Prisk
- Pulmonary Imaging Laboratory, Department of Medicine, University of California, San Diego
| | - Rui Carlos Sá
- Pulmonary Imaging Laboratory, Department of Medicine, University of California, San Diego;
| |
Collapse
|
21
|
Darquenne C, Elliott AR, Sibille B, Smales ET, DeYoung PN, Theilmann RJ, Malhotra A. Upper airway dynamic imaging during tidal breathing in awake and asleep subjects with obstructive sleep apnea and healthy controls. Physiol Rep 2018; 6:e13711. [PMID: 29845763 PMCID: PMC5974719 DOI: 10.14814/phy2.13711] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 02/07/2023] Open
Abstract
We used magnetic resonance imaging (MRI) to quantify change in upper airway dimension during tidal breathing in subjects with obstructive sleep apnea (OSA, N = 7) and BMI-matched healthy controls (N = 7) during both wakefulness and natural sleep. Dynamic MR images of the upper airway were obtained on a 1.5 T MR scanner in contiguous 7.5 mm-thick axial slices from the hard palate to the epiglottis along with synchronous MRI-compatible electroencephalogram and nasal/oral flow measurements. The physiologic data were retrospectively scored to identify sleep state, and synchronized with dynamic MR images. For each image, the upper airway was characterized by its area, and linear dimensions (lateral and anterior-posterior). The dynamic behavior of the upper airway was assessed by the maximum change in these parameters over the tidal breath. Mean upper airway caliber was obtained by averaging data over the tidal breath. There was no major difference in the upper airway structure between OSA and controls except for a narrower airway at the low-retropalatal/high-retroglossal level in OSA than in controls. Changes in upper airway size over the tidal breath ((maximum - minimum)/mean) were significantly larger in the OSA than in the control group in the low retropalatal/high retroglossal region during both wakefulness and sleep. In the four OSA subjects who experienced obstructive apneas during MR imaging, the site of airway collapse during sleep corresponded to the region of the upper airway where changes in caliber during awake tidal breathing were the greatest. These observations suggest a potential role for dynamic OSA imaging during wakefulness.
Collapse
Affiliation(s)
| | - Ann R. Elliott
- Division of PhysiologyUniversity of CaliforniaSan DiegoCalifornia
| | - Bastien Sibille
- Division of PhysiologyUniversity of CaliforniaSan DiegoCalifornia
| | - Erik T. Smales
- Division of PulmonaryCritical Care and Sleep MedicineUniversity of CaliforniaSan DiegoCalifornia
| | - Pamela N. DeYoung
- Division of PulmonaryCritical Care and Sleep MedicineUniversity of CaliforniaSan DiegoCalifornia
| | | | - Atul Malhotra
- Division of PulmonaryCritical Care and Sleep MedicineUniversity of CaliforniaSan DiegoCalifornia
| |
Collapse
|
22
|
Zapol WM, Charles HC, Martin AR, Sá RC, Yu B, Ichinose F, MacIntyre N, Mammarappallil J, Moon R, Chen JZ, Geier ET, Darquenne C, Prisk GK, Katz I. Pulmonary Delivery of Therapeutic and Diagnostic Gases. J Aerosol Med Pulm Drug Deliv 2018; 31:78-87. [PMID: 29451844 DOI: 10.1089/jamp.2017.1431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The 21st Congress for the International Society for Aerosols in Medicine included, for the first time, a session on Pulmonary Delivery of Therapeutic and Diagnostic Gases. The rationale for such a session within ISAM is that the pulmonary delivery of gaseous drugs in many cases targets the same therapeutic areas as aerosol drug delivery, and is in many scientific and technical aspects similar to aerosol drug delivery. This article serves as a report on the recent ISAM congress session providing a synopsis of each of the presentations. The topics covered are the conception, testing, and development of the use of nitric oxide to treat pulmonary hypertension; the use of realistic adult nasal replicas to evaluate the performance of pulsed oxygen delivery devices; an overview of several diagnostic gas modalities; and the use of inhaled oxygen as a proton magnetic resonance imaging (MRI) contrast agent for imaging temporal changes in the distribution of specific ventilation during recovery from bronchoconstriction. Themes common to these diverse applications of inhaled gases in medicine are discussed, along with future perspectives on development of therapeutic and diagnostic gases.
Collapse
Affiliation(s)
- Warren M Zapol
- 1 Anesthesia Center for Critical Care Research , Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - H Cecil Charles
- 2 Duke Image Analysis Laboratory, Center for Advanced MR Development, Department of Radiology, Duke University School of Medicine , Durham, North Carolina
| | - Andrew R Martin
- 3 Department of Mechanical Engineering, University of Alberta , Edmonton, Canada
| | - Rui C Sá
- 4 Department of Medicine, University of California , San Diego, San Diego, California
| | - Binglan Yu
- 1 Anesthesia Center for Critical Care Research , Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Fumito Ichinose
- 1 Anesthesia Center for Critical Care Research , Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Neil MacIntyre
- 5 Department of Pulmonology, Duke University School of Medicine , Durham, North Carolina
| | - Joseph Mammarappallil
- 6 Department of Radiology, Duke University School of Medicine , Durham, North Carolina
| | - Richard Moon
- 7 Department of Anesthesiology, Duke University School of Medicine , Durham, North Carolina
| | - John Z Chen
- 3 Department of Mechanical Engineering, University of Alberta , Edmonton, Canada
| | - Eric T Geier
- 4 Department of Medicine, University of California , San Diego, San Diego, California
| | - Chantal Darquenne
- 4 Department of Medicine, University of California , San Diego, San Diego, California
| | - G Kim Prisk
- 4 Department of Medicine, University of California , San Diego, San Diego, California.,8 Department of Radiology, University of California , San Diego, San Diego, California
| | - Ira Katz
- 9 Medical R&D, Air Liquide Santé International , Les Loges-en-Josas, France .,10 Department of Mechanical Engineering, Lafayette College , Easton, Pennsylvania
| |
Collapse
|
23
|
Hopkins SR, Elliott AR, Prisk GK, Darquenne C. Ventilation heterogeneity measured by multiple breath inert gas testing is not affected by inspired oxygen concentration in healthy humans. J Appl Physiol (1985) 2017; 122:1379-1387. [PMID: 28280107 DOI: 10.1152/japplphysiol.01013.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/03/2017] [Accepted: 03/08/2017] [Indexed: 11/22/2022] Open
Abstract
Multiple breath washout (MBW) and oxygen-enhanced MRI techniques use acute exposure to 100% oxygen to measure ventilation heterogeneity. Implicit is the assumption that breathing 100% oxygen does not induce changes in ventilation heterogeneity; however, this is untested. We hypothesized that ventilation heterogeneity decreases with increasing inspired oxygen concentration in healthy subjects. We performed MBW in 8 healthy subjects (4 women, 4 men; age = 43 ± 15 yr) with normal pulmonary function (FEV1 = 98 ± 6% predicted) using 10% argon as a tracer gas and oxygen concentrations of 12.5%, 21%, or 90%. MBW was performed in accordance with ERS-ATS guidelines. Subjects initially inspired air followed by a wash-in of test gas. Tests were performed in balanced order in triplicate. Gas concentrations were measured at the mouth, and argon signals rescaled to mimic a N2 washout, and analyzed to determine the distribution of specific ventilation (SV). Heterogeneity was characterized by the width of a log-Gaussian fit of the SV distribution and from Sacin and Scond indexes derived from the phase III slope. There were no significant differences in the ventilation heterogeneity due to altered inspired oxygen: histogram width (hypoxia 0.57 ± 0.11, normoxia 0.60 ± 0.08, hyperoxia 0.59 ± 0.09, P = 0.51), Scond (hypoxia 0.014 ± 0.011, normoxia 0.012 ± 0.015, hyperoxia 0.010 ± 0.011, P = 0.34), or Sacin (hypoxia 0.11 ± 0.04, normoxia 0.10 ± 0.03, hyperoxia 0.12 ± 0.03, P = 0.23). Functional residual capacity was increased in hypoxia (P = 0.04) and dead space increased in hyperoxia (P = 0.0001) compared with the other conditions. The acute use of 100% oxygen in MBW or MRI is unlikely to affect ventilation heterogeneity.NEW & NOTEWORTHY Hyperoxia is used to measure the distribution of ventilation in imaging and MBW but may alter the underlying ventilation distribution. We used MBW to evaluate the effect of inspired oxygen concentration on the ventilation distribution using 10% argon as a tracer. Short-duration exposure to hypoxia (12.5% oxygen) and hyperoxia (90% oxygen) during MBW had no significant effect on ventilation heterogeneity, suggesting that hyperoxia can be used to assess the ventilation distribution.
Collapse
Affiliation(s)
- Susan R Hopkins
- Department of Medicine, University of California, San Diego, La Jolla, California; and .,Department of Radiology, University of California, San Diego, La Jolla, California
| | - Ann R Elliott
- Department of Medicine, University of California, San Diego, La Jolla, California; and
| | - G Kim Prisk
- Department of Medicine, University of California, San Diego, La Jolla, California; and.,Department of Radiology, University of California, San Diego, La Jolla, California
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, California; and
| |
Collapse
|
24
|
Sá RC, Zeman KL, Bennett WD, Prisk GK, Darquenne C. Regional Ventilation Is the Main Determinant of Alveolar Deposition of Coarse Particles in the Supine Healthy Human Lung During Tidal Breathing. J Aerosol Med Pulm Drug Deliv 2017; 30:322-331. [PMID: 28277885 DOI: 10.1089/jamp.2016.1336] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND To quantify the relationship between regional lung ventilation and coarse aerosol deposition in the supine healthy human lung, we used oxygen-enhanced magnetic resonance imaging and planar gamma scintigraphy in seven subjects. METHODS Regional ventilation was measured in the supine posture in a 15 mm sagittal slice of the right lung. Deposition was measured by using planar gamma scintigraphy (coronal scans, 40 cm FOV) immediately postdeposition, 1 hour 30 minutes and 22 hours after deposition of 99mTc-labeled particles (4.9 μm MMAD, GSD 2.5), inhaled in the supine posture (flow 0.5 L/s, 15 breaths/min). The distribution of retained particles at different times was used to infer deposition in different airway regions, with 22 hours representing alveolar deposition. The fraction of total slice ventilation per quartile of lung height from the lung apex to the dome of the diaphragm at functional residual capacity was computed, and co-registered with deposition data-apices aligned-using a transmission scan as reference. The ratio of fractional alveolar deposition to fractional ventilation of each quartile (r) was used to evaluate ventilation and deposition matching (r > 1, regional aerosol deposition fraction larger than regional ventilation fraction). RESULTS r was not significantly different from 1 for all regions (1.04 ± 0.25, 1.08 ± 0.22, 1.03 ± 0.17, 0.92 ± 0.13, apex to diaphragm, p > 0.40) at the alveolar level (r22h). For retention times r0h and r1h30, only the diaphragmatic region at r1h30 differed significantly from 1. CONCLUSIONS These results support the hypothesis that alveolar deposition is directly proportional to ventilation for ∼5 μm particles that are inhaled in the supine posture and are consistent with previous simulation predictions that show that convective flow is the main determinant of aerosol transport to the lung periphery.
Collapse
Affiliation(s)
- Rui Carlos Sá
- 1 Pulmonary Imaging Laboratory, Department of Medicine, University of California , San Diego, La Jolla, California
| | - Kirby L Zeman
- 2 Department of Medicine, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - William D Bennett
- 2 Department of Medicine, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - G Kim Prisk
- 1 Pulmonary Imaging Laboratory, Department of Medicine, University of California , San Diego, La Jolla, California.,3 Pulmonary Imaging Laboratory, Department of Radiology, University of California , San Diego, La Jolla, California
| | - Chantal Darquenne
- 1 Pulmonary Imaging Laboratory, Department of Medicine, University of California , San Diego, La Jolla, California
| |
Collapse
|
25
|
Patz MD, Sá RC, Darquenne C, Elliott AR, Asadi AK, Theilmann RJ, Dubowitz DJ, Swenson ER, Prisk GK, Hopkins SR. Susceptibility to high-altitude pulmonary edema is associated with a more uniform distribution of regional specific ventilation. J Appl Physiol (1985) 2017; 122:844-852. [PMID: 28057815 DOI: 10.1152/japplphysiol.00494.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 12/29/2016] [Accepted: 01/03/2017] [Indexed: 01/09/2023] Open
Abstract
High-altitude pulmonary edema (HAPE) is a potentially fatal condition affecting high-altitude sojourners. The biggest predictor of HAPE development is a history of prior HAPE. Magnetic resonance imaging (MRI) shows that HAPE-susceptible (with a history of HAPE), but not HAPE-resistant (with a history of repeated ascents without illness) individuals develop greater heterogeneity of regional pulmonary perfusion breathing hypoxic gas (O2 = 12.5%), consistent with uneven hypoxic pulmonary vasoconstriction (HPV). Why HPV is uneven in HAPE-susceptible individuals is unknown but may arise from regionally heterogeneous ventilation resulting in an uneven stimulus to HPV. We tested the hypothesis that ventilation is more heterogeneous in HAPE-susceptible subjects (n = 6) compared with HAPE-resistant controls (n = 7). MRI specific ventilation imaging (SVI) was used to measure regional specific ventilation and the relative dispersion (SD/mean) of SVI used to quantify baseline heterogeneity. Ventilation heterogeneity from conductive and respiratory airways was measured in normoxia and hypoxia (O2 = 12.5%) using multiple-breath washout and heterogeneity quantified from the indexes Scond and Sacin, respectively. Contrary to our hypothesis, HAPE-susceptible subjects had significantly lower relative dispersion of specific ventilation than the HAPE-resistant controls [susceptible = 1.33 ± 0.67 (SD), resistant = 2.36 ± 0.98, P = 0.05], and Sacin tended to be more uniform (susceptible = 0.085 ± 0.009, resistant = 0.113 ± 0.030, P = 0.07). Scond was not significantly different between groups (susceptible = 0.019 ± 0.007, resistant = 0.020 ± 0.004, P = 0.67). Sacin and Scond did not change significantly in hypoxia (P = 0.56 and 0.19, respectively). In conclusion, ventilation heterogeneity does not change with short-term hypoxia irrespective of HAPE susceptibility, and lesser rather than greater ventilation heterogeneity is observed in HAPE-susceptible subjects. This suggests that the basis for uneven HPV in HAPE involves vascular phenomena.NEW & NOTEWORTHY Uneven hypoxic pulmonary vasoconstriction (HPV) is thought to incite high-altitude pulmonary edema (HAPE). We evaluated whether greater heterogeneity of ventilation is also a feature of HAPE-susceptible subjects compared with HAPE-resistant subjects. Contrary to our hypothesis, ventilation heterogeneity was less in HAPE-susceptible subjects and unaffected by hypoxia, suggesting a vascular basis for uneven HPV.
Collapse
Affiliation(s)
- Michael D Patz
- Department of Anesthesiology, University of Washington, Seattle, Washington
| | - Rui C Sá
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Ann R Elliott
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Amran K Asadi
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Rebecca J Theilmann
- Department of Radiology, University of California, San Diego, La Jolla, California; and
| | - David J Dubowitz
- Department of Radiology, University of California, San Diego, La Jolla, California; and
| | - Erik R Swenson
- Medical Service, Veterans Affairs Puget Sound Health Care System, University of Washington, Seattle, Washington
| | - G Kim Prisk
- Department of Medicine, University of California, San Diego, La Jolla, California.,Department of Radiology, University of California, San Diego, La Jolla, California; and
| | - Susan R Hopkins
- Department of Medicine, University of California, San Diego, La Jolla, California; .,Department of Radiology, University of California, San Diego, La Jolla, California; and
| |
Collapse
|
26
|
Abstract
After the presentation of 60 papers at the conference "Advancing Aerosol Dosimetry Research" (October 24-25, 2014 in Irvine, CA, USA), attendees submitted written descriptions of needed research. About 40 research needs were submitted. The suggestions fell into six broad categories: 1) Access to detailed anatomic data; 2) Access to subject-specific aerosol deposition datasets; 3) Improving current inhaled aerosol deposition models; 4) Some current experimental data needs and hot topics; 5) Linking exposure and deposition modeling to health endpoints; and 6) Developing guidelines for appropriate validation of dosimetry and risk assessment models. Summaries of suggestions are provided here as an update on research needs related to inhaled aerosol dosimetry modeling. Taken together, the recommendations support the overarching need for increased collaborations between dose modelers and those that use the models for risk assessments, aerosol medicine applications, design of toxicology experiments, and extrapolation across species. This paper is only a snapshot in time of perceived research needs from the conference attendees; it does not carry the approval of any agency or other group that plans research priorities or that funds research.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, CA 92093-0623, USA
| | - Mark D Hoover
- Respiratory Health Division, National Institute for Occupational Safety and Health, Morgantown, VA 26505-2888, USA
| | - Robert F Phalen
- Department of Medicine, Center for Occupational and Environmental Health, University of California, Irvine, CA 92617-1830, USA
| |
Collapse
|
27
|
Darquenne C, Lamm WJ, Fine JM, Corley RA, Glenny RW. Total and regional deposition of inhaled aerosols in supine healthy subjects and subjects with mild-to-moderate COPD. J Aerosol Sci 2016; 99:27-39. [PMID: 27493296 PMCID: PMC4968943 DOI: 10.1016/j.jaerosci.2016.01.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Despite substantial development of sophisticated subject-specific computational models of aerosol transport and deposition in human lungs, experimental validation of predictions from these new models is sparse. We collected aerosol retention and exhalation profiles in seven healthy volunteers and six subjects with mild-to-moderate COPD (FEV1 = 50-80%predicted) in the supine posture. Total deposition was measured during continuous breathing of 1 and 2.9 μm-diameter particles (tidal volume of 1 L, flow rate of 0.3 L/s and 0.75 L/s). Bolus inhalations of 1 μm particles were performed to penetration volumes of 200, 500 and 800 mL (flow rate of 0.5 L/s). Aerosol bolus dispersion (H), deposition, and mode shift (MS) were calculated from these data. There was no significant difference in total deposition between healthy subjects and those with COPD. Total deposition increased with increasing particle size and also with increasing flow rate. Similarly, there was no significant difference in aerosol bolus deposition between subject groups. Yet, the rate of increase in dispersion and of decrease in MS with increasing penetration volume was higher in subjects with COPD than in healthy volunteers (H: 0.798 ± 0.205 vs. 0.527 ± 0.122 mL/mL, p=0.01; MS: -0.271±0.129 vs. -0.145 ± 0.076 mL/mL, p=0.05) indicating larger ventilation inhomogeneities (based on H) and increased flow sequencing (based on MS) in the COPD than in the healthy group. In conclusion, in the supine posture, deposition appears to lack sensitivity for assessing the effect of lung morphology and/or ventilation distribution alteration induced by mild-to-moderate lung disease on the fate of inhaled aerosols. However, other parameters such as aerosol bolus dispersion and mode shift may be more sensitive parameters for evaluating models of lungs with moderate disease.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Wayne J. Lamm
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Janelle M. Fine
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | | | - Robb W. Glenny
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| |
Collapse
|
28
|
Theilmann RJ, Darquenne C, Elliott AR, Bailey BA, Conrad DJ. Characterizing Lung Disease in Cystic Fibrosis with Magnetic Resonance Imaging and Airway Physiology. PLoS One 2016; 11:e0157177. [PMID: 27337056 PMCID: PMC4919047 DOI: 10.1371/journal.pone.0157177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 05/25/2016] [Indexed: 11/30/2022] Open
Abstract
Translational investigations in cystic fibrosis (CF) have a need for improved quantitative and longitudinal measures of disease status. To establish a non-invasive quantitative MRI technique to monitor lung health in patients with CF and correlate MR metrics with airway physiology as measured by multiple breath washout (MBW). Data were collected in 12 CF patients and 12 healthy controls. Regional (central and peripheral lung) measures of fractional lung water density (FLD: air to 100% fluid) were acquired both at FRC and TLC on a 1.5T MRI. The median FLD (mFLD) and the FRC-to-TLC mFLD ratio were calculated for each region at both lung volumes. Spirometry and MBW data were also acquired for each subject. Ventilation inhomogeneities were quantified by the lung clearance index (LCI) and by indices Scond* and Sacin* that assess inhomogeneities in the conducting (central) and acinar (peripheral) lung regions, respectively. MBW indices and mFLD at TLC (both regions) were significantly elevated in CF (p<0.01) compared to controls. The mFLD at TLC (central: R = 0.82) and the FRC-to-TLC mFLD ratio (peripheral: R = -0.77) were strongly correlated with Scond* and LCI. CF patients had high lung water content at TLC when compared to controls. This is likely due to the presence of retained airway secretions and airway wall edema (more water) and to limited expansions of air trapping areas (less air) in CF subjects. FRC-to-TLC ratios of mFLD strongly correlated with central ventilation inhomogeneities. These combined measures may provide a useful marker of both retained mucus and air trapping in CF lungs.
Collapse
Affiliation(s)
- Rebecca J. Theilmann
- Department of Radiology, University of California San Diego, San Diego, California, United States of America
- * E-mail:
| | - Chantal Darquenne
- Department of Medicine, University of California San Diego, San Diego, California, United States of America
| | - Ann R. Elliott
- Department of Medicine, University of California San Diego, San Diego, California, United States of America
| | - Barbara A. Bailey
- Department of Mathematics and Statistics, San Diego State University, San Diego, California, United States of America
| | - Douglas J. Conrad
- Department of Medicine, University of California San Diego, San Diego, California, United States of America
| |
Collapse
|
29
|
Darquenne C, Hicks CB, Malhotra A. Last Word on Viewpoint: The ongoing need for good physiological investigation: Obstructive sleep apnea in HIV patients as a paradigm. J Appl Physiol (1985) 2016; 118:251. [PMID: 25593221 DOI: 10.1152/japplphysiol.00984.2014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Chantal Darquenne
- Division of Physiology, University of California, San Diego, California;
| | - Charles B Hicks
- Division of Infectious Diseases, University of California, San Diego, California; and
| | - Atul Malhotra
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, California
| |
Collapse
|
30
|
Darquenne C, Fleming JS, Katz I, Martin AR, Schroeter J, Usmani OS, Venegas J, Schmid O. Bridging the Gap Between Science and Clinical Efficacy: Physiology, Imaging, and Modeling of Aerosols in the Lung. J Aerosol Med Pulm Drug Deliv 2016; 29:107-26. [PMID: 26829187 DOI: 10.1089/jamp.2015.1270] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Development of a new drug for the treatment of lung disease is a complex and time consuming process involving numerous disciplines of basic and applied sciences. During the 2015 Congress of the International Society for Aerosols in Medicine, a group of experts including aerosol scientists, physiologists, modelers, imagers, and clinicians participated in a workshop aiming at bridging the gap between basic research and clinical efficacy of inhaled drugs. This publication summarizes the current consensus on the topic. It begins with a short description of basic concepts of aerosol transport and a discussion on targeting strategies of inhaled aerosols to the lungs. It is followed by a description of both computational and biological lung models, and the use of imaging techniques to determine aerosol deposition distribution (ADD) in the lung. Finally, the importance of ADD to clinical efficacy is discussed. Several gaps were identified between basic science and clinical efficacy. One gap between scientific research aimed at predicting, controlling, and measuring ADD and the clinical use of inhaled aerosols is the considerable challenge of obtaining, in a single study, accurate information describing the optimal lung regions to be targeted, the effectiveness of targeting determined from ADD, and some measure of the drug's effectiveness. Other identified gaps were the language and methodology barriers that exist among disciplines, along with the significant regulatory hurdles that need to be overcome for novel drugs and/or therapies to reach the marketplace and benefit the patient. Despite these gaps, much progress has been made in recent years to improve clinical efficacy of inhaled drugs. Also, the recent efforts by many funding agencies and industry to support multidisciplinary networks including basic science researchers, R&D scientists, and clinicians will go a long way to further reduce the gap between science and clinical efficacy.
Collapse
Affiliation(s)
- Chantal Darquenne
- 1 Department of Medicine, University of California , San Diego, La Jolla, California
| | - John S Fleming
- 2 National Institute of Health Research Biomedical Research Unit in Respiratory Disease , Southampton, United Kingdom .,3 Department of Medical Physics and Bioengineering, University Hospital Southampton NHS Foundation Trust , Southampton, United Kingdom
| | - Ira Katz
- 4 Medical R&D, Air Liquide Santé International, Centre de Recherche Paris-Saclay , Jouy-en-Josas, France .,5 Department of Mechanical Engineering, Lafayette College , Easton, Pennsylvania
| | - Andrew R Martin
- 6 Department of Mechanical Engineering, University of Alberta , Edmonton, Alberta, Canada
| | | | - Omar S Usmani
- 8 Airway Disease Section, National Heart and Lung Institute , Imperial College London and Royal Brompton Hospital, London, United Kingdom
| | - Jose Venegas
- 9 Department of Anesthesia (Bioengineering), MGH/Harvard, Boston, Massachusetts
| | - Otmar Schmid
- 10 Comprehensive Pneumology Center (CPC), Member of the German Center for Lung Research , Munich, Germany .,11 Institute of Lung Biology and Disease, Helmholtz Zentrum München-German Research Center for Environmental Health , Neuherberg, Germany
| |
Collapse
|
31
|
Sá RC, Zeman KL, Bennett WD, Prisk GK, Darquenne C. Effect of Posture on Regional Deposition of Coarse Particles in the Healthy Human Lung. J Aerosol Med Pulm Drug Deliv 2015; 28:423-31. [DOI: 10.1089/jamp.2014.1189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Rui Carlos Sá
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Kirby L. Zeman
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William D. Bennett
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - G. Kim Prisk
- Department of Medicine, University of California, San Diego, La Jolla, California
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, California
| |
Collapse
|
32
|
Oakes JM, Marsden AL, Grandmont C, Darquenne C, Vignon-Clementel IE. Distribution of aerosolized particles in healthy and emphysematous rat lungs: comparison between experimental and numerical studies. J Biomech 2015; 48:1147-57. [PMID: 25682537 DOI: 10.1016/j.jbiomech.2015.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/17/2014] [Accepted: 01/13/2015] [Indexed: 01/17/2023]
Abstract
In silico models of airflow and particle deposition in the lungs are increasingly used to determine the therapeutic or toxic effects of inhaled aerosols. While computational methods have advanced significantly, relatively few studies have directly compared model predictions to experimental data. Furthermore, few prior studies have examined the influence of emphysema on particle deposition. In this work we performed airflow and particle simulations to compare numerical predictions to data from our previous aerosol exposure experiments. Employing an image-based 3D rat airway geometry, we first compared steady flow simulations to coupled 3D-0D unsteady simulations in the healthy rat lung. Then, in 3D-0D simulations, the influence of emphysema was investigated by matching disease location to the experimental study. In both the healthy unsteady and steady simulations, good agreement was found between numerical predictions of aerosol delivery and experimental deposition data. However, deposition patterns in the 3D geometry differed between the unsteady and steady cases. On the contrary, satisfactory agreement was not found between the numerical predictions and experimental data for the emphysematous lungs. This indicates that the deposition rate downstream of the 3D geometry is likely proportional to airflow delivery in the healthy lungs, but not in the emphysematous lungs. Including small airway collapse, variations in downstream airway size and tissue properties, and tracking particles throughout expiration may result in a more favorable agreement in future studies.
Collapse
Affiliation(s)
- Jessica M Oakes
- INRIA Paris-Rocquencourt, 78153 Le Chesnay Cedex, France; Sorbonne Universités UPMC Univ. Paris 6, Laboratoire Jacques-Louis Lions, 75005 Paris, France
| | - Alison L Marsden
- Mechanical and Aerospace Engineering Department, University of California San Diego, La Jolla, CA 92093, USA
| | - Céline Grandmont
- INRIA Paris-Rocquencourt, 78153 Le Chesnay Cedex, France; Sorbonne Universités UPMC Univ. Paris 6, Laboratoire Jacques-Louis Lions, 75005 Paris, France
| | - Chantal Darquenne
- Department of Medicine, Division of Physiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Irene E Vignon-Clementel
- INRIA Paris-Rocquencourt, 78153 Le Chesnay Cedex, France; Sorbonne Universités UPMC Univ. Paris 6, Laboratoire Jacques-Louis Lions, 75005 Paris, France.
| |
Collapse
|
33
|
Darquenne C, Hicks CB, Malhotra A. The ongoing need for good physiological investigation: obstructive sleep apnea in HIV patients as a paradigm. J Appl Physiol (1985) 2015; 118:244-6. [PMID: 25150224 PMCID: PMC4315452 DOI: 10.1152/japplphysiol.00656.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Chantal Darquenne
- Division of Physiology, University of California, San Diego, California;
| | - Charles B Hicks
- Division of Infectious Diseases, University of California, San Diego, California; and
| | - Atul Malhotra
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, California
| |
Collapse
|
34
|
Darquenne C, Borja MG, Oakes JM, Breen EC, Olfert IM, Scadeng M, Prisk GK. Increase in relative deposition of fine particles in the rat lung periphery in the absence of gravity. J Appl Physiol (1985) 2014; 117:880-6. [PMID: 25170069 PMCID: PMC4199993 DOI: 10.1152/japplphysiol.00298.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 08/21/2014] [Indexed: 11/22/2022] Open
Abstract
While it is well recognized that pulmonary deposition of inhaled particles is lowered in microgravity (μG) compared with gravity on the ground (1G), the absence of sedimentation causes fine particles to penetrate deeper in the lung in μG. Using quantitative magnetic resonance imaging (MRI), we determined the effect of gravity on peripheral deposition (DEPperipheral) of fine particles. Aerosolized 0.95-μm-diameter ferric oxide particles were delivered to spontaneously breathing rats placed in plethysmographic chambers both in μG aboard the NASA Microgravity Research Aircraft and at 1G. Following exposure, lungs were perfusion fixed, fluid filled, and imaged in a 3T MR scanner. The MR signal decay rate, R2*, was measured in each voxel of the left lung from which particle deposition (DEP) was determined based on a calibration curve. Regional deposition was assessed by comparing DEP between the outer (DEPperipheral) and inner (DEPcentral) areas on each slice, and expressed as the central-to-peripheral ratio. Total lung deposition tended to be lower in μG compared with 1G (1.01 ± 0.52 vs. 1.43 ± 0.52 μg/ml, P = 0.1). In μG, DEPperipheral was larger than DEPcentral (P < 0.03), while, in 1G, DEPperipheral was not significantly different from DEPcentral. Finally, central-to-peripheral ratio was significantly less in μG than in 1G (P ≤ 0.05). These data show a larger fraction of fine particles depositing peripherally in μG than in 1G, likely beyond the large- and medium-sized airways. Although not measured, the difference in the spatial distribution of deposited particles between μG and 1G could also affect particle retention rates, with an increase in retention for particles deposited more peripherally.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, California;
| | - Maria G Borja
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California; and
| | - Jessica M Oakes
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California; and
| | - Ellen C Breen
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - I Mark Olfert
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Miriam Scadeng
- Department of Radiology, University of California, San Diego, La Jolla, California
| | - G Kim Prisk
- Department of Medicine, University of California, San Diego, La Jolla, California; Department of Radiology, University of California, San Diego, La Jolla, California
| |
Collapse
|
35
|
Abstract
The deposition of aerosol in the human lung occurs mainly through a combination of inertial impaction, gravitational sedimentation, and diffusion. For 0.5- to 5-μm-diameter particles and resting breathing conditions, the primary mechanism of deposition in the intrathoracic airways is sedimentation, and therefore the fate of these particles is markedly affected by gravity. Studies of aerosol deposition in altered gravity have mostly been performed in humans during parabolic flights in both microgravity (μG) and hypergravity (~1.6G), where both total deposition during continuous aerosol mouth breathing and regional deposition using aerosol bolus inhalations were performed with 0.5- to 3-μm particles. Although total deposition increased with increasing gravity level, only peripheral deposition as measured by aerosol bolus inhalations was strongly dependent on gravity, with central deposition (lung depth<200 mL) being similar between gravity levels. More recently, the spatial distribution of coarse particles (mass median aerodynamic diameter≈5 μm) deposited in the human lung was assessed using planar gamma scintigraphy. The absence of gravity caused a smaller portion of 5-μm particles to deposit in the lung periphery than in the central region, where deposition occurred mainly in the airways. Indeed, 5-μm-diameter particles deposit either by inertial impaction, a mechanism most efficient in the large and medium-sized airways, or by gravitational sedimentation, which is most efficient in the distal lung. On the contrary, for fine particles (~1 μm), both aerosol bolus inhalations and studies in small animals suggest that particles deposit more peripherally in μG than in 1G, beyond the reach of the mucociliary clearance system.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California , San Diego, La Jolla, CA
| |
Collapse
|
36
|
Oakes JM, Breen EC, Scadeng M, Tchantchou GS, Darquenne C. MRI-based measurements of aerosol deposition in the lung of healthy and elastase-treated rats. J Appl Physiol (1985) 2014; 116:1561-8. [PMID: 24790020 PMCID: PMC4064380 DOI: 10.1152/japplphysiol.01165.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Aerosolized drugs are increasingly being used to treat chronic lung diseases or to deliver therapeutics systemically through the lung. The influence of disease, such as emphysema, on particle deposition is not fully understood. With the use of magnetic resonance imaging (MRI), the deposition pattern of iron oxide particles with a mass median aerodynamic diameter of 1.2 μm was assessed in the lungs of healthy and elastase-treated rats. Tracheostomized rats were ventilated with particles, at a tidal volume of 2.2 ml, and a breathing frequency of 80 breaths/min. Maximum airway pressure was significantly lower in the elastase-treated (Paw = 7.71 ± 1.68 cmH2O) than in the healthy rats (Paw = 10.43 ± 1.02 cmH2O; P < 0.01). This is consistent with an increase in compliance characteristic of an emphysema-like lung structure. Following exposure, lungs were perfusion fixed and imaged in a 3T MR scanner. Particle concentration in the different lobes was determined based on a relationship with the MR signal decay rate, R2*. Whole lung particle deposition was significantly higher in the elastase-treated rats (CE,part = 3.03 ± 0.61 μm/ml) compared with the healthy rats (CH,part = 1.84 ± 0.35 μm/ml; P < 0.01). However, when particle deposition in each lobe was normalized by total deposition in the lung, there was no difference between the experimental groups. However, the relative dispersion [RD = standard deviation/mean] of R2* was significantly higher in the elastase-treated rats (RDE = 0.32 ± 0.02) compared with the healthy rats (RDH = 0.25 ± 0.02; P < 0.01). These data show that particle deposition is higher and more heterogeneously distributed in emphysematous lungs compared with healthy lungs.
Collapse
Affiliation(s)
- Jessica M Oakes
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, California
| | - Ellen C Breen
- Department of Medicine, Division of Physiology, University of California, San Diego, California
| | - Miriam Scadeng
- Department of Radiology, University of California, San Diego, California; and
| | | | - Chantal Darquenne
- Department of Medicine, Division of Physiology, University of California, San Diego, California;
| |
Collapse
|
37
|
Oakes JM, Marsden AL, Grandmont C, Shadden SC, Darquenne C, Vignon-Clementel IE. Airflow and particle deposition simulations in health and emphysema: from in vivo to in silico animal experiments. Ann Biomed Eng 2014; 42:899-914. [PMID: 24318192 PMCID: PMC4092242 DOI: 10.1007/s10439-013-0954-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 11/23/2013] [Indexed: 10/25/2022]
Abstract
Image-based in silico modeling tools provide detailed velocity and particle deposition data. However, care must be taken when prescribing boundary conditions to model lung physiology in health or disease, such as in emphysema. In this study, the respiratory resistance and compliance were obtained by solving an inverse problem; a 0D global model based on healthy and emphysematous rat experimental data. Multi-scale CFD simulations were performed by solving the 3D Navier-Stokes equations in an MRI-derived rat geometry coupled to a 0D model. Particles with 0.95 μm diameter were tracked and their distribution in the lung was assessed. Seven 3D-0D simulations were performed: healthy, homogeneous, and five heterogeneous emphysema cases. Compliance (C) was significantly higher (p = 0.04) in the emphysematous rats (C = 0.37 ± 0.14 cm(3)/cmH2O) compared to the healthy rats (C = 0.25 ± 0.04 cm(3)/cmH2O), while the resistance remained unchanged (p = 0.83). There were increases in airflow, particle deposition in the 3D model, and particle delivery to the diseased regions for the heterogeneous cases compared to the homogeneous cases. The results highlight the importance of multi-scale numerical simulations to study airflow and particle distribution in healthy and diseased lungs. The effect of particle size and gravity were studied. Once available, these in silico predictions may be compared to experimental deposition data.
Collapse
Affiliation(s)
- Jessica M Oakes
- Mechanical and Aerospace Engineering Department, University of California, San Diego, La Jolla, CA, 92093, USA
| | | | | | | | | | | |
Collapse
|
38
|
Sá RC, Asadi AK, Theilmann RJ, Hopkins SR, Prisk GK, Darquenne C. Validating the distribution of specific ventilation in healthy humans measured using proton MR imaging. J Appl Physiol (1985) 2014; 116:1048-56. [PMID: 24505099 DOI: 10.1152/japplphysiol.00982.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Specific ventilation imaging (SVI) uses proton MRI to quantitatively map the distribution of specific ventilation (SV) in the human lung, using inhaled oxygen as a contrast agent. To validate this recent technique, we compared the quantitative measures of heterogeneity of the SV distribution in a 15-mm sagittal slice of lung obtained in 10 healthy supine subjects, (age 37 ± 10 yr, forced expiratory volume in 1 s 97 ± 7% predicted) using SVI to those obtained in the whole lung from multiple-breath nitrogen washout (MBW). Using the analysis of Lewis et al. (Lewis SM, Evans JW, Jalowayski AA. J App Physiol 44: 416-423, 1978), the most likely distribution of SV from the MBW data was computed and compared with the distribution of SV obtained from SVI, after normalizing for the difference in tidal volume. The average SV was 0.30 ± 0.10 MBW, compared with 0.36 ± 0.10 SVI (P = 0.01). The width of the distribution, a measure of the heterogeneity, obtained using both methods was comparable: 0.51 ± 0.06 and 0.47 ± 0.08 in MBW and SVI, respectively (P = 0.15). The MBW estimated width of the SV distribution was 0.05 (10.7%) higher than that estimated using SVI, and smaller than the intertest variability of the MBW estimation [inter-MBW (SD) for the width of the SV distribution was 0.08 (15.8)%]. To assess reliability, SVI was performed twice on 13 subjects showing small differences between measurements of SV heterogeneity (typical error 0.05, 12%). In conclusion, quantitative estimations of SV heterogeneity from SVI are reliable and similar to those obtained using MBW, with SVI providing spatial information that is absent in MBW.
Collapse
Affiliation(s)
- Rui Carlos Sá
- Pulmonary Imaging Laboratory, Department of Medicine, University of California, San Diego, La Jolla, California
| | | | | | | | | | | |
Collapse
|
39
|
Abstract
RATIONALE Exposure to extraterrestrial dusts is an almost inevitable consequence of any proposed planetary exploration. Previous studies in humans showed reduced deposition in low-gravity compared with normal gravity (1G). However, the reduced sedimentation means that fewer particles deposit in the airways, increasing the number of particles transported to the lung periphery where they eventually deposit albeit at a smaller rate than in 1G. In this study, we determined the role that gravity and other mechanisms such as cardiogenic mixing play in peripheral lung deposition during breath holds. METHODS Eight healthy subjects inhaled boluses of 0.5 μm-diameter particles to penetration volumes (Vp) of 300 and 1200ml that were followed by breath holds of up to 10 sec. Tests were performed in 1G and during short periods of microgravity (μG) aboard the NASA Microgravity Research Aircraft. Aerosol deposition and dispersion were calculated from these data. RESULTS Results show that, for both Vp, deposition in 1G was significantly higher than in μG. In contrast, while dispersion was significantly higher in 1G compared to μG at Vp=1200ml, there was no significant gravitational effect on dispersion at Vp=300ml. Finally, for each G level and Vp, deposition and dispersion significantly increased with increasing breath-hold time. CONCLUSION The most important finding of this study is that, even in the absence of gravity, aerosol deposition in the lung periphery increased with increasing residence time. Because the particles used in this study were too large to be significantly affected by Brownian diffusion, the increase in deposition is likely due to cardiogenic motion effects.
Collapse
Affiliation(s)
- G. Kim Prisk
- Dept. of Medicine, UCSD, La Jolla, CA, USA
- Dept. of Radiology, UCSD, La Jolla, CA, USA
| | | | | |
Collapse
|
40
|
Darquenne C, Zeman KL, Sá RC, Cooper TK, Fine JM, Bennett WD, Prisk GK. Removal of sedimentation decreases relative deposition of coarse particles in the lung periphery. J Appl Physiol (1985) 2013; 115:546-55. [PMID: 23743403 DOI: 10.1152/japplphysiol.01520.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lung deposition of >0.5-μm particles is strongly influenced by gravitational sedimentation, with deposition being reduced in microgravity (μG) compared with normal gravity (1G). Gravity not only affects total deposition, but may also alter regional deposition. Using gamma scintigraphy, we measured the distribution of regional deposition and retention of radiolabeled particles ((99m)Tc-labeled sulfur colloid, 5-μm diameter) in five healthy volunteers. Particles were inhaled in a controlled fashion (0.5 l/s, 15 breaths/min) during multiple periods of μG aboard the National Aeronautics and Space Administration Microgravity Research Aircraft and in 1G. In both cases, deposition scans were obtained immediately postinhalation and at 1 h 30 min, 4 h, and 22 h postinhalation. Regional deposition was characterized by the central-to-peripheral ratio and by the skew of the distribution of deposited particles on scans acquired directly postinhalation. Relative distribution of deposition between the airways and the alveolar region was derived from data acquired at the various time points. Compared with inhalation in 1G, subjects show an increase in central-to-peripheral ratio (P = 0.043), skew (P = 0.043), and tracheobronchial deposition (P < 0.001) when particles were inhaled in μG. The absence of gravity caused fewer particles to deposit in the lung periphery than in the central region where deposition occurred mainly in the airways in μG. Furthermore, the increased skew observed in μG likely illustrates the presence of localized areas of deposition, i.e., "hot spots", resulting from inertial impaction. In conclusion, gravity has a significant effect on deposition patterns of coarse particles, with most of deposition occurring in the alveolar region in 1G but in the large airways in μG.
Collapse
Affiliation(s)
- C Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, California 92093-0623, USA.
| | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
INTRODUCTION Lunar dust may be a toxic challenge to astronauts. While deposition in reduced gravity is less than in normal gravity (1 G), reduced gravitational sedimentation causes particles to penetrate deeper in the lung, potentially causing more harm. The likely design of the lunar habitat has a reduced pressure environment and low-density gas has been shown to reduce upper airway deposition and increase peripheral deposition. METHODS Breathing air and a reduced-density gas approximating the density of the proposed lunar habitat atmosphere, five healthy subjects inhaled 1 -microm diameter aerosol boluses at penetration volumes (V(p)) of 200 ml (central airways), 500 ml, and 1000 ml (lung periphery) in microgravity during parabolic flight, and in 1 G. RESULTS Deposition in the lunar habitat was significantly less than for Earth conditions (and less than in 1 G with the low-density gas) with a relative decrease in deposition of -59.1 +/- 14.0% (-46.9 +/- 11.7%), -50.7 +/- 9.2% (-45.8 +/- 11.2%), and -46.0 +/- 8.3% (-45.3 +/- 11.1%) at V(p) = 200, 500, and 1000 ml, respectively. There was no significant effect of reduced density on deposition in 1 G. DISCUSSION While minimally affected by gas density, deposition was significantly less in microgravity than in 1 G for both gases, with a larger portion of particles depositing in the lung periphery under lunar conditions than Earth conditions. Thus, gravity, and not gas properties, mainly affects deposition in the peripheral lung, suggesting that studies of aerosol transport in the lunar habitat need not be performed at the low density proposed for the atmosphere in that environment.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, Mail Code 0623A, La Jolla, CA 92093-0623, USA.
| | | |
Collapse
|
42
|
Abstract
The aerosol bolus technique can be used to estimate the degree of convective mixing in the lung; however, contributions of different lung compartments to measured dispersion cannot be differentiated unambiguously. To estimate dispersion in the distal lung, we studied the effect of gravity and airway asymmetry on the dispersion of 1 μm-diameter particle boluses in three-dimensional computational models of the lung periphery, ranging from a single alveolar sac to four-generation (g4) structures of bifurcating airways that deformed homogeneously during breathing. Boluses were introduced at the beginning of a 2-s inhalation, immediately followed by a 3-s exhalation. Dispersion was estimated by the half-width of the exhaled bolus. Dispersion was significantly affected by the spatial orientation of the models in normal gravity and was less in zero gravity than in normal gravity. Dispersion was strongly correlated with model volume in both normal and zero gravity. Predicted pulmonary dispersion based on a symmetric g4 acinar model was 391 ml and 238 ml under normal and zero gravity, respectively. These results accounted for a significant amount of dispersion measured experimentally. In zero gravity, predicted dispersion in a highly asymmetric model accounted for ∼20% of that obtained in a symmetric model with comparable volume and number of alveolated branches, whereas normal gravity dispersions were comparable in both models. These results suggest that gravitational sedimentation and not geometrical asymmetry is the dominant factor in aerosol dispersion in the lung periphery.
Collapse
Affiliation(s)
- Baoshun Ma
- Department of Medicine, University of California, San Diego, La Jolla, California 92093-0623, USA
| | | |
Collapse
|
43
|
Abstract
The success of inhalation therapy is not only dependent upon the pharmacology of the drugs being inhaled but also upon the site and extent of deposition in the respiratory tract. This article reviews the main mechanisms affecting the transport and deposition of inhaled aerosol in the human lung. Aerosol deposition in both the healthy and diseased lung is described mainly based on the results of human studies using nonimaging techniques. This is followed by a discussion of the effect of flow regime on aerosol deposition. Finally, the link between therapeutic effects of inhaled drugs and their deposition pattern is briefly addressed. Data show that total lung deposition is a poor predictor of clinical outcome, and that regional deposition needs to be assessed to predict therapeutic effectiveness. Indeed, spatial distribution of deposited particles and, as a consequence, drug efficiency is strongly affected by particle size. Large particles (>6 μm) tend to mainly deposit in the upper airway, limiting the amount of drugs that can be delivered to the lung. Small particles (<2 μm) deposit mainly in the alveolar region and are probably the most apt to act systemically, whereas the particle in the size range 2-6 μm are be best suited to treat the central and small airways.
Collapse
Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0623, USA.
| |
Collapse
|
44
|
Abstract
Rodents have been widely used to study the environmental or therapeutic impact of inhaled particles. Knowledge of airway morphometry is essential in assessing geometric influence on aerosol deposition and in developing accurate lung models of aerosol transport. Previous morphometric studies of the rat lung performed ex situ provided high-resolution measurements (50-125 μm). However, it is unclear how the overall geometry of these casts might have differed from the natural in situ appearance. In this study, four male Wistar rat (268 ± 14 g) lungs were filled sequentially with perfluorocarbon and phosphate-buffered saline before being imaged in situ in a 7-T magnetic resonance (MR) scanner at a resolution of 0.2 × 0.2 × 0.27 mm. Airway length, diameter, gravitational, bifurcation, and rotational angles were measured for the first four airway generations from 3D geometric models built from the MR images. Minor interanimal variability [expressed by the relative standard deviation RSD (=SD/mean)] was found for length (0.18 ± 0.07), diameter (0.15 ± 0.15), and gravitational angle (0.12 ± 0.06). One rat model was extended to 16 airway generations. Organization of the airways using a diameter-defined Strahler ordering method resulted in lower interorder variability than conventional generation-based grouping for both diameter (RSD = 0.12 vs. 0.42) and length (0.16 vs. 0.67). Gravitational and rotational angles averaged 82.9 ± 37.9° and 53.6 ± 24.1°, respectively. Finally, the major daughter branch bifurcated at a smaller angle (19.3 ± 14.6°) than the minor branch (60.5 ± 19.4°). These data represent the most comprehensive set of rodent in situ measurements to date and can be used readily in computational studies of lung function and aerosol exposure.
Collapse
Affiliation(s)
- Jessica M Oakes
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA
| | | | | | | | | |
Collapse
|
45
|
Abstract
Most previous computational studies on aerosol transport in models of the central airways of the human lung have focused on deposition, rather than transport of particles through these airways to the subtended lung regions. Using a model of the bronchial tree extending from the trachea to the segmental bronchi (J Appl Physiol 98: 970-980, 2005), we predicted aerosol delivery to the lung segments. Transport of 0.5- to 10-μm-diameter particles was computed at various gravity levels (0-1.6 G) during steady inspiration (100-500 ml/s). For each condition, the normalized aerosol distribution among the lung segments was compared with the normalized flow distribution by calculating the ratio (R(i)) of the number of particles exiting each segmental bronchus i to the flow. When R(i) = 1, particle transport was directly proportional to segmental flow. Flow and particle characteristics were represented by the Stokes number (Stk) in the trachea. For Stk < 0.01, R(i) values were close to 1 and were unaffected by gravity. For Stk > 0.01, R(i) varied greatly among the different outlets (R(i) = 0.30-1.93 in normal gravity for 10-μm particles at 500 ml/s) and was affected by gravity and inertia. These data suggest that, for Stk < 0.01, ventilation defines the delivery of aerosol to lung segments and that the use of aerosol tracers is a valid technique to visualize ventilation in different parts of the lung. At higher Stokes numbers, inertia, but not gravitational sedimentation, is the second major factor affecting the transport of large particles in the lung.
Collapse
Affiliation(s)
- C Darquenne
- Division of Physiology 0931, Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0931, USA.
| | | | | |
Collapse
|
46
|
Abstract
Although the major mechanisms of aerosol deposition in the lung are known, detailed quantitative data in anatomically realistic models are still lacking, especially in the acinar airways. In this study, an algorithm was developed to build multigenerational three-dimensional models of alveolated airways with arbitrary bifurcation angles and spherical alveolar shape. Using computational fluid dynamics, the deposition of 1- and 3-μm aerosol particles was predicted in models of human alveolar sac and terminal acinar bifurcation under rhythmic wall motion for two breathing conditions (functional residual capacity = 3 liter, tidal volume = 0.5 and 0.9 liter, breathing period = 4 s). Particles entering the model during one inspiration period were tracked for multiple breathing cycles until all particles deposited or escaped from the model. Flow recirculation inside alveoli occurred only during transition between inspiration and expiration and accounted for no more than 1% of the whole cycle. Weak flow irreversibility and convective transport were observed in both models. The average deposition efficiency was similar for both breathing conditions and for both models. Under normal gravity, total deposition was ~33 and 75%, of which ~67 and 96% occurred during the first cycle, for 1- and 3-μm particles, respectively. Under zero gravity, total deposition was ~2-5% for both particle sizes. These results support previous findings that gravitational sedimentation is the dominant deposition mechanism for micrometer-sized aerosols in acinar airways. The results also showed that moving walls and multiple breathing cycles are needed for accurate estimation of aerosol deposition in acinar airways.
Collapse
Affiliation(s)
- Baoshun Ma
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0931, USA
| | | |
Collapse
|
47
|
Moore GS, Wong SC, Darquenne C, Neuman TS, West JB, Kim Prisk G. Ventilation-perfusion inequality in the human lung is not increased following no-decompression-stop hyperbaric exposure. Eur J Appl Physiol 2009; 107:545-52. [PMID: 19690884 PMCID: PMC2767514 DOI: 10.1007/s00421-009-1150-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2009] [Indexed: 11/29/2022]
Abstract
Venous gas bubbles occur in recreational SCUBA divers in the absence of decompression sickness, forming venous gas emboli (VGE) which are trapped within pulmonary circulation and cleared by the lung without overt pathology. We hypothesized that asymptomatic VGE would transiently increase ventilation-perfusion mismatch due to their occlusive effects within the pulmonary circulation. Two sets of healthy volunteers (n = 11, n = 12) were recruited to test this hypothesis with a single recreational ocean dive or a baro-equivalent dry hyperbaric dive. Pulmonary studies (intrabreath VA/Q (iV/Q), alveolar dead space, and FVC) were conducted at baseline and repeat 1- and 24-h after the exposure. Contrary to our hypothesis VA/Q mismatch was decreased 1-h post-SCUBA dive (iV/Q slope 0.023 ± 0.008 ml−1 at baseline vs. 0.010 ± 0.005 NS), and was significantly reduced 24-h post-SCUBA dive (0.000 ± 0.005, p < 0.05), with improved VA/Q homogeneity inversely correlated to dive severity. No changes in VA/Q mismatch were observed after the chamber dive. Alveolar dead space decreased 24-h post-SCUBA dive (78 ± 10 ml at baseline vs. 56 ± 5, p < 0.05), but not 1-h post dive. FVC rose 1-h post-SCUBA dive (5.01 ± 0.18 l vs. 5.21 ± 0.26, p < 0.05), remained elevated 24-h post SCUBA dive (5.06 ± 0.2, p < 0.05), but was decreased 1-hr after the chamber dive (4.96 ± 0.31 L to 4.87 ± 0.32, p < 0.05). The degree of VA/Q mismatch in the lung was decreased following recreational ocean dives, and was unchanged following an equivalent air chamber dive, arguing against an impact of VGE on the pulmonary circulation.
Collapse
|
48
|
Darquenne C, Harrington L, Prisk GK. Alveolar duct expansion greatly enhances aerosol deposition: a three-dimensional computational fluid dynamics study. Philos Trans A Math Phys Eng Sci 2009; 367:2333-46. [PMID: 19414458 PMCID: PMC2696106 DOI: 10.1098/rsta.2008.0295] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Obtaining in vivo data of particle transport in the human lung is often difficult, if not impossible. Computational fluid dynamics (CFD) can provide detailed information on aerosol transport in realistic airway geometries. This paper provides a review of the key CFD studies of aerosol transport in the acinar region of the human lung. It also describes the first ever three-dimensional model of a single fully alveolated duct with moving boundaries allowing for the cyclic expansion and contraction that occurs during breathing. Studies of intra-acinar aerosol transport performed in models with stationary walls (SWs) showed that flow patterns were influenced by the geometric characteristics of the alveolar aperture, the presence of the alveolar septa contributed to the penetration of the particles into the lung periphery and there were large inhomogeneities in deposition patterns within the acinar structure. Recent studies have now used acinar models with moving walls. In these cases, particles penetrate the alveolar cavities not only as a result of sedimentation and diffusion but also as a result of convective transport, resulting in a much higher deposition prediction than that in SW models. Thus, models that fail to incorporate alveolar wall motions probably underestimate aerosol deposition in the acinar region of the lung.
Collapse
Affiliation(s)
- C Darquenne
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, mail code 0931, La Jolla, CA 92093-0931, USA.
| | | | | |
Collapse
|
49
|
Ma B, Ruwet V, Corieri P, Theunissen R, Riethmuller M, Darquenne C. CFD Simulation and Experimental Validation of Fluid Flow and Particle Transport in a Model of Alveolated Airways. J Aerosol Sci 2009; 40:403-141. [PMID: 20161301 PMCID: PMC2699293 DOI: 10.1016/j.jaerosci.2009.01.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Accurate modeling of air flow and aerosol transport in the alveolated airways is essential for quantitative predictions of pulmonary aerosol deposition. However, experimental validation of such modeling studies has been scarce. The objective of this study is to validate CFD predictions of flow field and particle trajectory with experiments within a scaled-up model of alveolated airways. Steady flow (Re = 0.13) of silicone oil was captured by particle image velocimetry (PIV), and the trajectories of 0.5 mm and 1.2 mm spherical iron beads (representing 0.7 to 14.6 mum aerosol in vivo) were obtained by particle tracking velocimetry (PTV). At twelve selected cross sections, the velocity profiles obtained by CFD matched well with those by PIV (within 1.7% on average). The CFD predicted trajectories also matched well with PTV experiments. These results showed that air flow and aerosol transport in models of human alveolated airways can be simulated by CFD techniques with reasonable accuracy.
Collapse
Affiliation(s)
- Baoshun Ma
- Dept. of Medicine, University of California, San Diego, La Jolla, CA, U.S.A
| | - Vincent Ruwet
- von Karman Institute for Fluid Dynamics, Rhode-St-Genèse, Belgium
| | - Patricia Corieri
- von Karman Institute for Fluid Dynamics, Rhode-St-Genèse, Belgium
| | - Raf Theunissen
- von Karman Institute for Fluid Dynamics, Rhode-St-Genèse, Belgium
| | | | - Chantal Darquenne
- Dept. of Medicine, University of California, San Diego, La Jolla, CA, U.S.A
- Corresponding author: Chantal Darquenne, Ph.D., Associate Professor, Department of Medicine, University of California, San Diego, 9500 Gilman Drive # 0931, La Jolla, CA 92093-0931, Phone (858)455-4756, FAX (858)455-4765,
| |
Collapse
|
50
|
Peterson JB, Prisk GK, Darquenne C. Aerosol deposition in the human lung periphery is increased by reduced-density gas breathing. J Aerosol Med Pulm Drug Deliv 2008; 21:159-68. [PMID: 18518792 DOI: 10.1089/jamp.2007.0651] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Aerosol mixing resulting from turbulent flows is thought to be a major mechanism of deposition in the upper respiratory tract (URT). Because turbulence levels are a function of gas density, the use of a low-density carrier gas should reduce deposition in the URT allowing the aerosol to reach more peripheral airways of the lung. We performed aerosol bolus tests on 11 healthy subjects to investigate the effect of reduced gas density on regional aerosol deposition in the human lung. Using both air and heliox (80% helium, 20% oxygen) as carrier gas, boluses of 1 and 2 microm-diameter particles were inhaled to five volumetric lung depths (V(p)) between 150 and 1200 mL during an inspiration from residual volume (RV) to 1 liter above functional residual capacity at a constant flow rate of approximately 0.50 L/sec, which was immediately followed by an expiration to RV at the same flow rate. Aerosol deposition and axial dispersion were calculated from aerosol concentration and flow rate measured at the mouth. For 1 microm-diameter particles, deposition was significantly reduced by 29 +/- 28% (mean +/- SD, p < 0.05) when breathing heliox instead of air at shallow V(p) (150 mL) and significantly increased by 11 +/- 9% at deep V(p) (1200 mL). For 2 microm-diameter particles, deposition was significantly higher at V(p) = 500 mL by 6 +/- 7% and the predicted V(p) to achieve 100% deposition was significantly lower with heliox (834 +/- 146 mL) compared to air (912 +/- 128 mL) (p < 0.05). Despite a decrease in deposition at shallow V(p), there was no change in axial dispersion, suggesting that other factors such as radial turbulent mixing result in decreased aerosol deposition. Our results suggested that heliox reduces upper airway deposition of 1 and 2 microm-diameter particles allowing more particles to penetrate and subsequently deposit in the peripheral lung.
Collapse
Affiliation(s)
- Jonathan B Peterson
- Department of Medicine, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | | | | |
Collapse
|