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Kaminsky DA, Cockcroft DW, Davis BE. Respiratory System Dynamics. Semin Respir Crit Care Med 2023; 44:526-537. [PMID: 37429331 DOI: 10.1055/s-0043-1770058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
While static mechanical forces govern resting lung volumes, dynamic forces determine tidal breathing, airflow, and changes in airflow and lung volume during normal and abnormal breathing. This section will examine the mechanisms, measurement methodology, and interpretation of the dynamic changes in airflow and lung volume that occur in health and disease. We will first examine how the total work of breathing can be described by the parameters of the equation of motion, which determine the pressure required to move air into and out of the lung. This will include a detailed description of airflow characteristics and airway resistance. Next, we will review the changes in pressure and flow that determine maximal forced inspiration and expiration, which result in the maximal flow-volume loop and the clinically important forced expired volume in 1 second. We will also assess the mechanisms and interpretation of bronchodilator responsiveness, dynamic hyperinflation, and airways hyperresponsiveness.
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Affiliation(s)
- David A Kaminsky
- Division of Pulmonary and Critical Care, Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Donald W Cockcroft
- Division of Respirology, Critical Care and Sleep Medicine, University of Saskatchewan College of Medicine, Saskatoon Saskatchewan, Canada
| | - Beth E Davis
- Division of Respirology, Critical Care and Sleep Medicine, University of Saskatchewan College of Medicine, Saskatoon Saskatchewan, Canada
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2
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Abstract
This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.
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Affiliation(s)
- David A Kaminsky
- University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - David G Chapman
- University of Technology Sydney, Sydney, New South Wales, Australia
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Area Under the Expiratory Flow-Volume Curve (AEX): Assessing Bronchodilator Responsiveness. Lung 2020; 198:471-480. [PMID: 32211978 PMCID: PMC7242267 DOI: 10.1007/s00408-020-00345-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 03/11/2020] [Indexed: 11/30/2022]
Abstract
Background Area under expiratory flow–volume curve (AEX) is a useful spirometric tool in stratifying respiratory impairment. The AEX approximations based on isovolumic flows can be used with reasonable accuracy when AEX is unavailable. We assessed here pre- to post-bronchodilator (BD) variability of AEX4 as a functional assessment tool for lung disorders. Methods The BD response was assessed in 4330 subjects by changes in FEV1, FVC, and AEX4, which were derived from FVC, peak expiratory flow, and forced expiratory flow at 25%, 50%, and 75% FVC. Newly proposed BD response categories (negative, minimal, mild, moderate and marked) have been investigated in addition to standard criteria. Results Using standard BD criteria, 24% of subjects had a positive response. Using the new BD response categories, only 23% of subjects had a negative response; 45% minimal, 18% mild, 9% moderate, and 5% had a marked BD response. Mean percent change of the square root AEX4 was 0.3% and 14.3% in the standard BD-negative and BD-positive response groups, respectively. In the new BD response categories of negative, minimal, mild, moderate, and marked, mean percent change of square root AEX4 was − 8.2%, 2.9%, 9.2%, 15.0%, and 24.8%, respectively. Conclusions Mean pre- to post-BD variability of AEX4 was < 6% and stratified well between newly proposed categories of BD response (negative, minimal, mild, moderate and marked). We suggest that AEX4 (AEX) could become a useful measurement for stratifying dysfunction in obstructive lung disease and invite further investigation into indications for using bronchodilator agents or disease-modifying, anti-inflammatory therapies.
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Sferrazza Papa GF, Pellegrino GM, Pellegrino R. Asthma and respiratory physiology: putting lung function into perspective. Respirology 2014; 19:960-9. [PMID: 25060051 DOI: 10.1111/resp.12355] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 05/11/2014] [Accepted: 05/26/2014] [Indexed: 10/25/2022]
Abstract
Bronchial asthma is a chronic disease characterized by airway hyperresponsiveness, airway inflammation and remodelling. The hypothesis that the illness is inflammatory in nature has recently been challenged by studies showing that airway smooth muscle (ASM) plays a more important role than previously thought. For example, it is now known that in asthma patients, ASM proliferates more and faster than in healthy subjects, carries intrinsic defects and exhibits impaired relaxation, increased velocity of shortening, plastic adaptation to short length and perturbed equilibrium of actin-to-myosin during cycling. Similar conclusions can be drawn from studies on airway mechanics. For instance, in asthma, abnormal ASM contributes to limiting the response to deep lung stretching and accelerates the return of bronchial tone to baseline conditions, and contributes to increased airway stiffness. Upon stimulation, ASM causes airway narrowing that is heterogeneous across the lung and variable over time. This heterogeneity leads to patchy ventilation. Experimental studies have shown that patchy ventilation may precipitate an asthma attack, and inability to maintain bronchial tone control over time can predict the occurrence of bronchospastic attacks over a matter of a few days. To improve our knowledge on the pathogenesis of asthma, we believe that it is necessary to explore the disease within the framework of the topographical, volume and time domains of the lung that play an important role in setting the severity and progression of the disease. Application of the forced oscillation technique and multiple breath nitrogen washout may, alone or in combination, help address questions unsolvable until now.
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Obstructive sleep apnea and asthma: associations and treatment implications. Sleep Med Rev 2013; 18:165-71. [PMID: 23890469 DOI: 10.1016/j.smrv.2013.04.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 04/12/2013] [Accepted: 04/24/2013] [Indexed: 12/19/2022]
Abstract
Obstructive sleep apnea (OSA) and asthma are highly prevalent respiratory disorders and are frequently co-morbid. Risk factors common to the two diseases include obesity, rhinitis, and gastroesophageal reflux (GER). Observational and experimental evidence implicates airways and systemic inflammation, neuromechanical effects of recurrent upper airway collapse, and asthma-controlling medications (corticosteroids) as additional explanatory factors. Therefore, undiagnosed or inadequately treated OSA may adversely affect control of asthma and vice versa. It is important for clinicians to be vigilant and specifically address weight-control, nasal obstruction, and GER in these populations. Utilizing validated screening instruments to affirm high risk of co-morbid OSA or asthma in persistently symptomatic patients will allow clinicians to cost-effectively test and treat appropriate patients, potentially improving outcomes. While non-invasive ventilation in acute asthma improves outcomes, the role of chronic continuous positive airway pressure (CPAP; the first-line treatment for OSA) in improving long-term asthma control is not known. Future research should focus on the impact of optimal CPAP therapy and adherence on asthma symptoms and outcomes.
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Farrow CE, Salome CM, Harris BE, Bailey DL, Bailey E, Berend N, Young IH, King GG. Airway closure on imaging relates to airway hyperresponsiveness and peripheral airway disease in asthma. J Appl Physiol (1985) 2012; 113:958-66. [PMID: 22837168 DOI: 10.1152/japplphysiol.01618.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The regional pattern and extent of airway closure measured by three-dimensional ventilation imaging may relate to airway hyperresponsiveness (AHR) and peripheral airways disease in asthmatic subjects. We hypothesized that asthmatic airways are predisposed to closure during bronchoconstriction in the presence of ventilation heterogeneity and AHR. Fourteen asthmatic subjects (6 women) underwent combined ventilation single photon emission computed tomography/computed tomography scans before and after methacholine challenge. Regional airway closure was determined by complete loss of ventilation following methacholine challenge. Peripheral airway disease was measured by multiple-breath nitrogen washout from which S(cond) (index of peripheral conductive airway abnormality) was derived. Relationships between airway closure and lung function were examined by multiple-linear regression. Forced expiratory volume in 1 s was 87.5 ± 15.8% predicted, and seven subjects had AHR. Methacholine challenge decreased forced expiratory volume in 1 s by 23 ± 5% and increased nonventilated volume from 16 ± 4 to 29 ± 13% of computed tomography lung volume. The increase in airway closure measured by nonventilated volume correlated independently with both S(cond) (partial R(2) = 0.22) and with AHR (partial R(2) = 0.38). The extent of airway closure induced by methacholine inhalation in asthmatic subjects is greater with increasing peripheral airways disease, as measured by ventilation heterogeneity, and with worse AHR.
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Affiliation(s)
- Catherine E Farrow
- Woolcock Institute of Medical Research, Glebe, New South Wales, Australia.
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The use of bronchodilators in people with recently acquired tetraplegia: a randomised cross-over trial. Spinal Cord 2012; 50:836-9. [PMID: 22641256 DOI: 10.1038/sc.2012.62] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
STUDY DESIGN A within-participant, double-blind, cross-over, randomised control trial. OBJECTIVES To determine the short-term effects of bronchodilator therapy on respiratory function in people with recently acquired motor complete tetraplegia. SETTING Hospital, Australia. METHODS A total of 12 people with recently acquired tetraplegia were randomised to receive either a one-off dose of a bronchodilator followed by an equivalent dose of a placebo propellant between 1 day and 1 week later or visa versa. The three outcomes were forced expiratory volume in 1 s (FEV1), peak expiratory flow rate (PEF) and forced vital capacity (FVC). These were measured while supine by a blinded assessor 10 and 30 min after treatment. Data were analysed on 11 participants and reported as percentage of predicted. RESULTS The FEV1, FVC and PEF mean between-group differences (95% confidence interval) at 10 min post treatment were 7.3% (2.7-11.9%; P=0.003), 5.5% (1.6-9.4%; P=0.008) and 20.1% (1.1-40.4%; P=0.039). Similar effects were observed at 30 min for FVC and FEV1 but not for PEF. CONCLUSION Bronchodilator therapy has a beneficial effect on FEV1, FVC and PEF in participants with recently acquired tetraplegia.
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Pellegrino R, Pellegrino GM, Brusasco V. CPAP as a novel treatment for bronchial asthma? J Appl Physiol (1985) 2011; 111:343-4. [PMID: 21659492 DOI: 10.1152/japplphysiol.00676.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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King GG, Harris B, Mahadev S. V/Q SPECT: utility for investigation of pulmonary physiology. Semin Nucl Med 2011; 40:467-73. [PMID: 20920636 DOI: 10.1053/j.semnuclmed.2010.07.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Single-photon emission computed tomography (SPECT) is being increasingly used as a tool in respiratory research, in particular ventilation SPECT. Much of the basic understanding of pulmonary physiology has been derived from inhaled radioactive inert gases because, as the lung behaves in an asymmetric manner, the nature of regional differences in ventilation is ideally studied with the use of imaging. It is well known to clinicians that ventilation is patchy in patients who have airways disease. However, the relevance to the disease mechanisms itself only started to be studied with the use of 3-dimensional imaging and with advances in quantitative image analysis. The measurements of both ventilation distribution and nonventilation (airway closure) have become very topical in the study of asthma, and accurate quantification of those parameters is of relevance to disease mechanisms. In chronic obstructive pulmonary disease, the drive is towards better characterization of disease groups ("phenotypes") and, again, description of ventilation patterns may prove to be useful. This is a review, therefore, on pulmonary SPECT imaging in respiratory research which includes a focus on methodology in relation to respiratory physiology. There has been relatively little published in this area but there is great potential for advances in the understanding of airways disease to be gained from SPECT imaging.
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Affiliation(s)
- Gregory G King
- Woolcock Institute of Medical Research, Sydney, NSW, Australia; University of Sydney, Sydney, NSW, Australia.
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Kaminsky DA. Peripheral lung mechanics in asthma: exploring the outer limits. Pulm Pharmacol Ther 2010; 24:199-202. [PMID: 21146626 DOI: 10.1016/j.pupt.2010.12.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 11/29/2010] [Accepted: 12/06/2010] [Indexed: 10/18/2022]
Abstract
Asthma is a disease characterized by airways hyperresponsiveness (AHR), which is traditionally thought to involve the large, central airways. However, there is increasing evidence of the importance of peripheral airway involvement in asthma as well. Our group has developed particular expertise in measuring peripheral lung mechanics in both humans and mice. This presentation will review data on lung mechanics in subjects with asthma obtained by both classical means and uniquely through the wedged bronchoscope, as well as relevant experiments in mice. Our findings reveal that the lung periphery is hyperresponsive to stimuli in asthmatic subjects, with evidence of airway closure. We also show that the overall impedance of the lung is determined by a combination of peripheral airway narrowing and central airway shunting that occurs in both normal and asthmatic subjects. Experiments in mice have revealed the importance of airway closure in contributing to the phenomenon of AHR. Based on the effects of fibrin on lung mechanics, fibrin may contribute to airway closure via inactivation of surfactant. Another mechanism contributing to AHR is the heterogeneity of airway narrowing. We have explored this in humans by combining the forced oscillation technique with computerized tomography imaging of the lung, and demonstrated that heterogeneity is common to both normal and asthmatic subjects. Further experiments are ongoing and planned in both mice and humans to elucidate the role of fibrin, surfactant and heterogeneous airway narrowing and closure in contributing to AHR in asthma.
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Affiliation(s)
- David A Kaminsky
- Pulmonary Disease and Critical Care Medicine, University of Vermont College of Medicine, Given D-213, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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Madani A, Van Muylem A, Gevenois PA. Pulmonary Emphysema: Effect of Lung Volume on Objective Quantification at Thin-Section CT. Radiology 2010; 257:260-8. [DOI: 10.1148/radiol.10091446] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Pellegrino R, Pompilio P, Quaranta M, Aliverti A, Kayser B, Miserocchi G, Fasano V, Cogo A, Milanese M, Cornara G, Brusasco V, Dellacà R. Airway responses to methacholine and exercise at high altitude in healthy lowlanders. J Appl Physiol (1985) 2010; 108:256-65. [DOI: 10.1152/japplphysiol.00677.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peribronchial edema has been proposed as a mechanism enhancing airway responses to constrictor stimuli. Acute exposure to altitude in nonacclimatized lowlanders leads to subclinical interstitial pulmonary edema that lasts for several days after ascent, as suggested by changes in lung mechanics. We, therefore, investigated whether changes in lung mechanics consistent with fluid accumulation at high altitude within the lungs are associated with changes in airway responses to methacholine or exercise. Fourteen healthy subjects were studied at 4,559 and at 120 m above sea level. At high altitude, both static and dynamic lung compliances and respiratory reactance at 5 Hz significantly decreased, suggestive of interstitial pulmonary edema. Resting minute ventilation significantly increased by ∼30%. Compared with sea level, inhalation of methacholine at high altitude caused a similar reduction of partial forced expiratory flow but less reduction of maximal forced expiratory flow, less increments of pulmonary resistance and respiratory resistance at 5 Hz, and similar effects of deep breath on pulmonary and respiratory resistance. During maximal incremental exercise at high altitude, partial forced expiratory flow gradually increased with the increase in minute ventilation similarly to sea level but both achieved higher values at peak exercise. In conclusion, airway responsiveness to methacholine at high altitude is well preserved despite the occurrence of interstitial pulmonary edema. We suggest that this may be the result of the increase in resting minute ventilation opposing the effects and/or the development of airway smooth muscle force, reduced gas density, and well preserved airway-to-parenchyma interdependence.
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Affiliation(s)
- Riccardo Pellegrino
- Allergologia e Fisiopatologia Respiratoria, Azienda Ospedaliera S. Croce e Carle, Cuneo
| | - Pasquale Pompilio
- TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Marco Quaranta
- TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Andrea Aliverti
- TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Bengt Kayser
- Ecole d’Education Physique et de Sport; Institut des Sciences du Mouvement et de la Médecine du Sport; Université de Genève, Genève, Switzerland
| | | | - Valter Fasano
- Istituto di Malattie dell’Apparato Respiratorio, Università di Milano, Milano
| | - Annalisa Cogo
- Centro Studi Biomedici Applicati allo Sport, Università di Ferrara, Ferrara
| | | | - Giuseppe Cornara
- Anestesia e Rianimazione, Azienda Ospedaliera S. Croce e Carle, Cuneo
| | - Vito Brusasco
- Fisiopatologia Respiratoria, Dipartimento di Medicina Interna, Università di Genova, Genova, Italy
| | - Raffaele Dellacà
- TBM Lab, Dipartimento di Bioingegneria, Politecnico di Milano, Milano, Italy
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Baroffio M, Barisione G, Crimi E, Brusasco V. Noninflammatory mechanisms of airway hyper-responsiveness in bronchial asthma: an overview. Ther Adv Respir Dis 2009; 3:163-74. [PMID: 19661157 DOI: 10.1177/1753465809343595] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Airway hyper-responsiveness (AHR) is a cardinal feature of asthma. Its absence has been considered useful in excluding asthma, whereas it may be present in other diseases such as atopic rhinitis and chronic obstructive pulmonary disease. AHR is often considered an epiphenomenon of airway inflammation. Actually, the response of airways to constrictor stimuli is modulated by a complex array of factors, some facilitating and others opposing airway narrowing. Thus, it has been suggested that AHR, and perhaps asthma, might be present even without or before the development of airway inflammation. We begin this review by highlighting some terminological and methodological issues concerning the measurement of AHR. Then we describe the neurohumoral mechanisms controlling airway tone. Finally, the pivotal role of airway smooth muscle and internal and external modulation of airway caliber in vivo are discussed in detail.
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Affiliation(s)
- Michele Baroffio
- Dipartimento di Medicina Interna, Università di Genova, Genova, Italy.
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Torchio R, Gobbi A, Gulotta C, Dellacà R, Tinivella M, Hyatt RE, Brusasco V, Pellegrino R. Mechanical effects of obesity on airway responsiveness in otherwise healthy humans. J Appl Physiol (1985) 2009; 107:408-16. [DOI: 10.1152/japplphysiol.00083.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated whether obesity is associated with airway hyperresponsiveness in otherwise healthy humans and, if so, whether this correlates with a restrictive lung function pattern or a decreased number of sighs at rest and/or during walking. Lung function was studied before and after inhaling methacholine (MCh) in 41 healthy subjects with body mass index ranging from 20 to 56. Breathing pattern was assessed during a 60-min rest period and a 30-min walk. The dose of MCh that produced a 50% decrease in the maximum expiratory flow measured in a body plethysmograph (PD50MCh) was inversely correlated with body mass index ( r2 = 0.32, P < 0.001) and waist circumference ( r2 = 0.25, P < 0.001). Significant correlations with body mass index were also found with the maximum changes in respiratory resistance ( r2 = 0.19, P < 0.001) and reactance ( r2 = 0.40, P < 0.001) measured at 5 Hz. PD50MCh was also positively correlated with functional residual capacity ( r2 = 0.56, P < 0.001) and total lung capacity ( r2 = 0.59, P < 0.001) in men, but not in women. Neither PD50MCh nor body mass index correlated with number of sighs, average tidal volume, ventilation, or breathing frequency. In this study, airway hyperresponsiveness was significantly associated with obesity in otherwise healthy subjects. In obese men, but not in women, airway hyperresponsiveness was associated with the decreases in lung volumes.
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Harris RS, Winkler T, Musch G, Vidal Melo MF, Schroeder T, Tgavalekos N, Venegas JG. The prone position results in smaller ventilation defects during bronchoconstriction in asthma. J Appl Physiol (1985) 2009; 107:266-74. [PMID: 19443742 DOI: 10.1152/japplphysiol.91386.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of body posture on regional ventilation during bronchoconstriction is unknown. In five subjects with asthma, we measured spirometry, low-frequency (0.15-Hz) lung elastance, and resistance and regional ventilation by intravenous (13)NN-saline positron emission tomography before and after nebulized methacholine. The subjects were imaged prone on 1 day and supine on another, but on both days the methacholine was delivered while prone. From the residual (13)NN after washout, ventilation defective areas were defined, and their location, volume, ventilation, and fractional gas content relative to the rest of the lung were calculated. Independent of posture, all subjects developed ventilation defective areas. Although ventilation within these areas was similarly reduced in both postures, their volume was smaller in prone than supine (25 vs. 41%, P < 0.05). The geometric center of the ventilation defective areas was gravitationally dependent relative to that of the lung in both postures. Mean lung fractional gas content was greater in the prone position before methacholine and did not increase as much as in the supine position after methacholine. In the prone position at baseline, areas that became ventilation defects had lower gas content than the rest of the lung. In both positions at baseline, there was a gradient of gas content in the vertical direction. In asthma, the size and location of ventilation defects is affected by body position and likely affected by small differences in lung expansion during bronchoconstriction.
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Affiliation(s)
- R Scott Harris
- Department of Medicine, Pulmonary and Critical Care Unit, Bulfinch 148, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
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Pellegrino R, Pompilio PP, Bruni GI, Scano G, Crimi C, Biasco L, Coletta G, Cornara G, Torchio R, Brusasco V, Dellacà RL. Airway hyperresponsiveness with chest strapping: A matter of heterogeneity or reduced lung volume? Respir Physiol Neurobiol 2009; 166:47-53. [DOI: 10.1016/j.resp.2009.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 01/20/2009] [Accepted: 01/25/2009] [Indexed: 12/01/2022]
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Changes in obesity status and lung function decline in a general population sample. Respir Med 2008; 102:674-80. [DOI: 10.1016/j.rmed.2007.12.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 11/20/2022]
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Kaminsky DA, Irvin CG, Lundblad LKA, Thompson-Figueroa J, Klein J, Sullivan MJ, Flynn F, Lang S, Bourassa L, Burns S, Bates JHT. Heterogeneity of bronchoconstriction does not distinguish mild asthmatic subjects from healthy controls when supine. J Appl Physiol (1985) 2007; 104:10-9. [PMID: 17947503 DOI: 10.1152/japplphysiol.00519.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heterogeneity is a fundamental property of airway constriction; however, whether it is a distinguishing feature of mild asthma is not clear. We used computerized tomography and the forced oscillation technique to compare lung heterogeneity between 18 mildly asthmatic and 19 healthy control subjects at similar levels of bronchoconstriction while subjects were supine. We also assessed the effects of deep inhalation and albuterol on supine lung mechanics. Measures of heterogeneity included lung attenuation, from which we derived a novel index of air-space size, and the frequency dependence of respiratory system resistance between 1 and 20 Hz. We found that asthmatic subjects had airways hyperresponsiveness to methacholine in the sitting position compared with controls, but both groups had similar falls in forced expiratory volume in 1 s after inhaling methacholine while supine. There were no baseline differences between the groups in the frequency dependence of resistance, or lung attenuation, before methacholine, and both groups responded similarly with an increase in air-space size (+9.2% vs. +3.4%), air-space size heterogeneity (+9.8% vs. +4.2%), and frequency dependence of resistance (+76% vs. +86%) after methacholine. Deep inhalation did not affect resistance in either group, but albuterol significantly reduced resistance in both groups. We conclude that both computerized tomography and the forced oscillation technique demonstrate increased heterogeneity of airway narrowing during induced bronchoconstriction while supine and that this heterogeneity is equivalent between subjects with mild asthma and healthy controls when bronchoconstricted to the same degree. Thus heterogeneity appears to be a fundamental feature of bronchoconstriction and is not unique to mild asthma.
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Affiliation(s)
- David A Kaminsky
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont 05405, USA.
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Yim S, Fredberg J, Malhotra A. Continuous positive airway pressure for asthma: not a big stretch? Eur Respir J 2007; 29:226-8. [PMID: 17264319 PMCID: PMC3496923 DOI: 10.1183/09031936.00160206] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- S. Yim
- Divisions of Sleep Medicine and Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital, Boston, MA, USA
| | - J.J. Fredberg
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - A. Malhotra
- Divisions of Sleep Medicine and Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital, Boston, MA, USA
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