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Neder JA, Santyr G, Zanette B, Kirby M, Pourafkari M, James MD, Vincent SG, Ferguson C, Wang CY, Domnik NJ, Phillips DB, Porszasz J, Stringer WW, O'Donnell DE. Beyond Spirometry: Linking Wasted Ventilation to Exertional Dyspnea in the Initial Stages of COPD. COPD 2024; 21:2301549. [PMID: 38348843 DOI: 10.1080/15412555.2023.2301549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 12/29/2023] [Indexed: 02/15/2024]
Abstract
Exertional dyspnea, a key complaint of patients with chronic obstructive pulmonary disease (COPD), ultimately reflects an increased inspiratory neural drive to breathe. In non-hypoxemic patients with largely preserved lung mechanics - as those in the initial stages of the disease - the heightened inspiratory neural drive is strongly associated with an exaggerated ventilatory response to metabolic demand. Several lines of evidence indicate that the so-called excess ventilation (high ventilation-CO2 output relationship) primarily reflects poor gas exchange efficiency, namely increased physiological dead space. Pulmonary function tests estimating the extension of the wasted ventilation and selected cardiopulmonary exercise testing variables can, therefore, shed unique light on the genesis of patients' out-of-proportion dyspnea. After a succinct overview of the basis of gas exchange efficiency in health and inefficiency in COPD, we discuss how wasted ventilation translates into exertional dyspnea in individual patients. We then outline what is currently known about the structural basis of wasted ventilation in "minor/trivial" COPD vis-à-vis the contribution of emphysema versus a potential impairment in lung perfusion across non-emphysematous lung. After summarizing some unanswered questions on the field, we propose that functional imaging be amalgamated with pulmonary function tests beyond spirometry to improve our understanding of this deeply neglected cause of exertional dyspnea. Advances in the field will depend on our ability to develop robust platforms for deeply phenotyping (structurally and functionally), the dyspneic patients showing unordinary high wasted ventilation despite relatively preserved FEV1.
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Affiliation(s)
- J Alberto Neder
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
| | - Giles Santyr
- Translational Medicine Department, Faculty of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Canada
| | - Brandon Zanette
- Translational Medicine Department, Faculty of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Canada
| | - Miranda Kirby
- Department of Physics, Faculty of Science, Toronto Metropolitan University, Toronto, Canada
| | - Marina Pourafkari
- Department of Radiology and Diagnostic Imaging, Kingston Health Sciences Centre, Kingston, Canada
| | - Matthew D James
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
| | - Carrie Ferguson
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - Chu-Yi Wang
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - Nicolle J Domnik
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Devin B Phillips
- School of Kinesiology and Health Science, York University, Toronto, Canada
| | - Janos Porszasz
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - William W Stringer
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
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Panza L, Piamonti D, Palange P. Pulmonary gas exchange and ventilatory efficiency during exercise in health and diseases. Expert Rev Respir Med 2024:1-13. [PMID: 38912849 DOI: 10.1080/17476348.2024.2370447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 06/17/2024] [Indexed: 06/25/2024]
Abstract
INTRODUCTION Cardiopulmonary exercise testing (CPET) is nowadays used to study the exercise response in healthy subjects and in disease. Ventilatory efficiency is one of the main determinants in exercise tolerance, and its main variables are a useful tool to guide pathophysiologists toward specific diagnostic pathways, providing prognostic information and improving disease management, treatment, and outcomes. AREAS COVERED This review will be based on today's available scientific evidence, describing the main physiological determinants of ventilatory efficiency at rest and during exercise, and focusing also on how CPET variables are modified in specific diseases, leading to the possibility of early diagnosis and management. EXPERT OPINION Growing knowledge on CPET interpretation and a wider use of this clinical tool is expected in order to offer more precise diagnostic and prognostic information to patients and clinicians, helping in the management of therapeutic decisions. Future research could be able to identify new and more simple markers of ventilatory efficiency, and to individuate new interventions for the improvement of symptoms, such as exertional dyspnea.
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Affiliation(s)
- Luigi Panza
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
| | - Daniel Piamonti
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
| | - Paolo Palange
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
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Balasubramanian A, Gearhart AS, Putcha N, Fawzy A, Singh A, Wise RA, Hansel NN, McCormack MC. Diffusing Capacity as a Predictor of Hospitalizations in a Clinical Cohort of Chronic Obstructive Pulmonary Disease. Ann Am Thorac Soc 2024; 21:243-250. [PMID: 37870393 PMCID: PMC10848911 DOI: 10.1513/annalsats.202301-014oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023] Open
Abstract
Rationale: Chronic obstructive pulmonary disease (COPD) hospitalizations are a major burden on patients. Diffusing capacity of the lung for carbon monoxide (DlCO) is a potential predictor that has not been studied in large cohorts. Objectives: This study used electronic health record data to evaluate whether clinically obtained DlCO predicts COPD hospitalizations. Methods: We performed time-to-event analyses of individuals with COPD and DlCO measurements from the Johns Hopkins COPD Precision Medicine Center of Excellence. Cox proportional hazard methods were used to model time from DlCO measurement to first COPD hospitalization and composite first hospitalization or death, adjusting for age, sex, race, body mass index, smoking status, forced expiratory volume in 1 second (FEV1), history of prior COPD hospitalization, and comorbidities. To identify the utility of including DlCO in risk models, area under the receiver operating curve (AUC) values were calculated for models with and without DlCO. Results were externally validated in a separate analogous cohort. Results: Of 2,793 participants, 368 (13%) had a COPD hospitalization within 3 years. In adjusted analyses, for every 10% decrease in DlCO% predicted, risk of COPD hospitalization increased by 10% (hazard ratio, 1.1; 95% confidence interval, 1.1-1.2; P < 0.001). Similar associations were observed for COPD hospitalizations or death. The model including demographics, comorbidities, FEV1, DlCO, and prior COPD hospitalizations performed well, with an AUC of 0.85 and an AUC of 0.84 in an external validation cohort. Conclusions: Diffusing capacity is a strong predictor of COPD hospitalizations in a clinical cohort of individuals with COPD, independent of airflow obstruction and prior hospitalizations. These findings support incorporation of DlCO in risk assessment of patients with COPD.
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Affiliation(s)
- Aparna Balasubramanian
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Andrew S. Gearhart
- Research and Exploratory Development Department, Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland; and
| | - Nirupama Putcha
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Ashraf Fawzy
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Anil Singh
- Division of Pulmonary, Critical Care, Allergy, and Sleep, Alleghany Health Network, Highmark Health, Pittsburgh, Pennsylvania
| | - Robert A. Wise
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Nadia N. Hansel
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Meredith C. McCormack
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
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Hopkins SR, Stickland MK. The Pulmonary Vasculature. Semin Respir Crit Care Med 2023; 44:538-554. [PMID: 37816344 PMCID: PMC11192587 DOI: 10.1055/s-0043-1770059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The pulmonary circulation is a low-pressure, low-resistance circuit whose primary function is to deliver deoxygenated blood to, and oxygenated blood from, the pulmonary capillary bed enabling gas exchange. The distribution of pulmonary blood flow is regulated by several factors including effects of vascular branching structure, large-scale forces related to gravity, and finer scale factors related to local control. Hypoxic pulmonary vasoconstriction is one such important regulatory mechanism. In the face of local hypoxia, vascular smooth muscle constriction of precapillary arterioles increases local resistance by up to 250%. This has the effect of diverting blood toward better oxygenated regions of the lung and optimizing ventilation-perfusion matching. However, in the face of global hypoxia, the net effect is an increase in pulmonary arterial pressure and vascular resistance. Pulmonary vascular resistance describes the flow-resistive properties of the pulmonary circulation and arises from both precapillary and postcapillary resistances. The pulmonary circulation is also distensible in response to an increase in transmural pressure and this distention, in addition to recruitment, moderates pulmonary arterial pressure and vascular resistance. This article reviews the physiology of the pulmonary vasculature and briefly discusses how this physiology is altered by common circumstances.
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Affiliation(s)
- Susan R. Hopkins
- Department of Radiology, University of California, San Diego, California
| | - Michael K. Stickland
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta
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Shlomi D, Beck T, Reuveny R, Segel MJ. Prediction of exercise respiratory limitation from pulmonary function tests. Pulmonology 2023:S2531-0437(23)00001-6. [PMID: 36717291 DOI: 10.1016/j.pulmoe.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 12/11/2022] [Accepted: 12/22/2022] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Evaluation of unexplained exercise intolerance is best resolved by cardiopulmonary exercise testing (CPET) which enables the determination of the exercise limiting system in most cases. Traditionally, pulmonary function tests (PFTs) at rest are not used for the prediction of a respiratory limitation on CPET. OBJECTIVE We sought cut-off values on PFTs that might, a priori, rule-in or rule-out a respiratory limitation in CPET. METHODS Patients who underwent CPET in our institute were divided into two groups according to spirometry: obstructive and non-obstructive. Each group was randomly divided 2:1 into derivation and validation cohorts respectively. We analyzed selected PFTs parameters in the derivation groups in order to establish maximal and minimal cut-off values for which a respiratory limitation could be ruled-in or ruled-out. We then validated these values in the validation cohorts. RESULTS Of 593 patients who underwent a CPET, 126 were in the obstructive and 467 in the non-obstructive group. In patients with obstructive lung disease, forced expiratory volume in 1 second (FEV1) ≥ 61% predicted could rule out a respiratory limitation, while FEV1 ≤ 33% predicted was always associated with a respiratory limitation. For patients with non-obstructive spirometry, FEV1 of ≥ 73% predicted could rule-out a respiratory limitation. Application of this algorithm might have saved up to 47% and 71% of CPETs in our obstructive and non-obstructive groups, respectively. CONCLUSION Presence or absence of a respiratory limitation on CPET can be predicted in some cases based on a PFTs performed at rest.
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Affiliation(s)
- D Shlomi
- Adelson School of Medicine, Ariel University, Ariel, Israel; Pulmonary Clinic, Dan-Petah-Tiqwa District, Clalit Health Services - Community Division, Ramat-Gan, Israel.
| | - T Beck
- Department of Surgical Oncology (Surgery C), Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - R Reuveny
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; Pulmonary Institute, Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel; Physical Therapy Department, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
| | - M J Segel
- Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; Pulmonary Institute, Sheba Medical Center, Tel-HaShomer, Ramat Gan, Israel
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Phillips DB, James MD, O'Donnell CJD, Vincent SG, Webb KA, de-Torres JP, Neder JA, O'Donnell DE. Physiological Predictors of Morbidity and Mortality in COPD: The Relative Importance of Reduced Inspiratory Capacity and Inspiratory Muscle Strength. J Appl Physiol (1985) 2022; 133:679-688. [PMID: 35952349 DOI: 10.1152/japplphysiol.00352.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Low resting inspiratory capacity (IC) and low maximal inspiratory pressure (MIP) have previously been linked to exertional dyspnea, exercise limitation and poor survival in chronic obstructive pulmonary disease (COPD). The interaction and relative contributions of these two related variables to important clinical outcomes are unknown. The objective of the current study was to examine the interaction between resting IC and MIP (both % predicted), exertional dyspnea, exercise capacity and long-term survival in patients with COPD. Two hundred and eighty-five patients with mild to advanced COPD completed standard lung function testing and a cycle cardiopulmonary exercise test. Multiple regression determined predictors of the exertional dyspnea-ventilation slope and peak oxygen uptake (V̇O2peak). Cox regression determined predictors of 10-year mortality. IC was associated with the dyspnea-ventilation slope (standardized β=-0.44, p<0.001), while MIP was excluded from the regression model (p=0.713). IC and MIP were included in the final model to predict V̇O2peak. However, the standardized β was greater for IC (0.49) than MIP (0.22). After adjusting for age, sex, body mass index, cardiovascular risk, airflow obstruction and diffusing capacity, resting IC was independently associated with 10-year all-cause mortality (hazard ratio=1.25, confidence interval5-95%=1.16-1.34, p<0.001), while MIP was excluded from the final model (all p=0.829). Low resting IC was consistently linked to heightened dyspnea intensity, low V̇O2peak and worse survival in COPD even after accounting for airway obstruction, inspiratory muscle strength, and diffusing capacity. These results support the use of resting IC as an important physiological biomarker closely linked to key clinical outcomes in COPD.
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Affiliation(s)
- Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Matthew D James
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Conor J D O'Donnell
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Katherine A Webb
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Juan Pablo de-Torres
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine and Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
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7
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Phillips DB, Elbehairy AF, James MD, Vincent SG, Milne KM, de-Torres JP, Neder JA, Kirby M, Jensen D, Stickland MK, Guenette JA, Smith BM, Aaron SD, Tan WC, Bourbeau J, O'Donnell DE. Impaired Ventilatory Efficiency, Dyspnea and Exercise Intolerance in Chronic Obstructive Pulmonary Disease: Results from the CanCOLD Study. Am J Respir Crit Care Med 2022; 205:1391-1402. [PMID: 35333135 DOI: 10.1164/rccm.202109-2171oc] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Impaired exercise ventilatory efficiency (high ventilatory requirements for CO2 [V̇E/V̇CO2]) provides an indication of pulmonary gas exchange abnormalities in chronic obstructive pulmonary disease (COPD). OBJECTIVES To determine: 1) the association between high V̇E/V̇CO2 and clinical outcomes (dyspnea and exercise capacity) and its relationship to lung function and structural radiographic abnormalities; and 2) its prevalence in a large population-based cohort. METHODS Participants were recruited randomly from the population and underwent clinical evaluation, pulmonary function, cardiopulmonary exercise testing and chest computed tomography (CT). Impaired exercise ventilatory efficiency was defined by a nadir V̇E/V̇CO2 above the upper limit of normal (V̇E/V̇CO2>ULN), using population-based normative values. MEASUREMENTS AND MAIN RESULTS Participants included 445 never-smokers, 381 ever-smokers without airflow obstruction, 224 with GOLD 1 COPD, and 200 with GOLD 2-4 COPD. Participants with V̇E/V̇CO2>ULN were more likely to have activity-related dyspnea (Medical Research Council dyspnea scale≥2, odds ratio=1.77[1.31-2.39]) and abnormally low peak oxygen uptake (V̇O2peak<LLN, odds ratio=4.58[3.06-6.86]). The carbon monoxide transfer coefficient (KCO) had a stronger correlation with nadir V̇E/V̇CO2 (r=-0.38, p<0.001) than other relevant lung function and CT metrics. The prevalence of V̇E/V̇CO2>ULN was 24% in COPD (similar in GOLD 1 and 2-4), which was greater than in never-smokers (13%) and ever-smokers (12%). CONCLUSIONS V̇E/V̇CO2>ULN was associated with greater dyspnea and low VO2peak and was present in 24% of all participants with COPD, regardless of GOLD stage. The results show the importance of recognizing impaired exercise ventilatory efficiency as a potential contributor to dyspnea and exercise limitation, even in mild COPD.
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Affiliation(s)
| | - Amany F Elbehairy
- Queen's University and Kingston General Hospital, Medicine, Kingston, Ontario, Canada.,Alexandria University, Department of Chest Diseases, Faculty of Medicine, Alexandria, Egypt
| | - Matthew D James
- Queen's University, 4257, Medicine, Kingston, Ontario, Canada
| | | | - Kathryn M Milne
- The University of British Columbia, 8166, Medicine, Vancouver, British Columbia, Canada
| | | | - J Alberto Neder
- Queen's University, 4257, Medicine, Kingston, Ontario, Canada
| | - Miranda Kirby
- Ryerson University, Physics, Toronto, Ontario, Canada
| | - Dennis Jensen
- McGill University, Kinesiology & Physical Education, Montreal, Quebec, Canada
| | | | | | - Benjamin M Smith
- McGill University, Respiratory Medicine, Montreal, Quebec, Canada
| | - Shawn D Aaron
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Wan C Tan
- Providence Heart & Lung Institute, University of British Columbia, St Paul's Hospital, UBC James Hogg Research Centre, Vancouver, British Columbia, Canada
| | - Jean Bourbeau
- Montreal Chest Institute, CORE, Montreal, Quebec, Canada.,McGill University Health Centre, 54473, Montreal, Quebec, Canada
| | - Denis E O'Donnell
- Queen's University, Division of Respiratory and Critical Care Medicine, Department of Medicine, Kingston, Ontario, Canada;
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8
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Mkorombindo T, Dransfield MT. Pre-chronic obstructive pulmonary disease: a pathophysiologic process or an opinion term? Curr Opin Pulm Med 2022; 28:109-114. [PMID: 34907960 DOI: 10.1097/mcp.0000000000000854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Current guidelines does not include current or former smokers who do not have spirometric airflow limitation in their diagnostic or therapeutic algorithms for chronic obstructive pulmonary disease (COPD). The purpose of this review is to outline the burden of respiratory morbidity in this population and to discuss the potential utility of their classification as pre-COPD. RECENT FINDINGS It is increasingly clear that patients with a history of exposure to cigarette smoke or other environmental pollutants may have substantial lung pathology and respiratory impairment even in the absence of airflow limitation, as detected by spirometry. Not all of these patients will develop airflow limitation, but many will have considerable respiratory morbidity and a comparable prognosis to those with classical, spirometrically defined COPD. The use of the term pre-COPD may allow for the identification of these individuals in order to target preventive and earlier therapeutic strategies. SUMMARY Spirometry is not adequately sensitive to identify many current and former smokers and other exposed populations with significant lung pathology and respiratory symptoms. Though the pathologic processes present in these patients differ, the earlier identification of this pre-COPD population may foster the development of more effective and disease-modifying treatments.
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Affiliation(s)
- Takudzwa Mkorombindo
- Lung Health Center, Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
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9
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Neder JA, Berton DC, Phillips DB, O'Donnell DE. Exertional ventilation/carbon dioxide output relationship in COPD: from physiological mechanisms to clinical applications. Eur Respir Rev 2021; 30:30/161/200190. [PMID: 34526312 PMCID: PMC9489189 DOI: 10.1183/16000617.0190-2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/30/2020] [Indexed: 01/09/2023] Open
Abstract
There is well established evidence that the minute ventilation (V′E)/carbon dioxide output (V′CO2) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased V′E/V′CO2 reflects an enlarged physiological dead space (“wasted” ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The V′E/V′CO2 nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1 s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high V′E/V′CO2 is valuable to ascertain a role for the “lungs” in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase V′E/V′CO2. A high V′E/V′CO2 is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the V′E/V′CO2 should be valued in the clinical management of patients with COPD. The minute ventilation/carbon dioxide production relationship is relevant to a number of patient-related outcomes in COPD. Minute ventilation/carbon dioxide production, therefore, should be valued in the clinical management of these patients.https://bit.ly/3df2upH
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Affiliation(s)
- J Alberto Neder
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Danilo C Berton
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada.,Division of Respiratory Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Devin B Phillips
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada
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10
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James MD, Phillips DB, Elbehairy AF, Milne KM, Vincent SG, Domnik NJ, de Torres JP, Neder JA, O'Donnell DE. Mechanisms of Exertional Dyspnea in Patients with Mild COPD and a Low Resting DL CO. COPD 2021; 18:501-510. [PMID: 34496691 DOI: 10.1080/15412555.2021.1932782] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Patients with mild chronic obstructive pulmonary disease (COPD) and lower resting diffusing capacity for carbon monoxide (DLCO) often report troublesome dyspnea during exercise although the mechanisms are not clear. We postulated that in such individuals, exertional dyspnea is linked to relatively high inspiratory neural drive (IND) due, in part, to the effects of reduced ventilatory efficiency. This cross-sectional study included 28 patients with GOLD I COPD stratified into two groups with (n = 15) and without (n = 13) DLCO less than the lower limit of normal (<LLN; Global Lung Function Initiative criteria) and 16 healthy controls. We compared dyspnea (Borg scale), IND (by diaphragm electromyography), ventilatory equivalent for CO2 (V̇E/V̇CO2), and respiratory mechanics during incremental cycle exercise in the three groups. Spirometry and resting lung volumes were similar between COPD groups. During exercise, dyspnea, IND and V̇E/V̇CO2 were higher at equivalent work rates (WR) in the DLCO<LLN group compared with the other two groups (all p < 0.05). In patients with DLCO<LLN, severe respiratory mechanical constraints, indicated by end-inspiratory lung volume of approximately 90% of total lung capacity, occurred at a lower WR than the other two groups (p < 0.05). The dyspnea/IND relationship was similar across groups; therefore, the increased dyspnea at a standardized WR in the low DLCO<LLN group reflected the higher corresponding IND. Higher dyspnea ratings in patients with mild COPD and DLCO<LLN were associated with higher IND and V̇E/V̇CO2 at a given work rate. Higher ventilatory requirements in the DLCO<LLN group accelerated dynamic mechanical abnormalities earlier in exercise, further increasing IND and dyspnea.
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Affiliation(s)
- Matthew D James
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Amany F Elbehairy
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada.,Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Kathryn M Milne
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada.,Centre for Heart Lung Innovation, Providence Health Care Research Institute, University of British Colombia, St. Paul's Hospital, Vancouver, British Columbia, Canada.,Division of Respiratory Medicine, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Nicolle J Domnik
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Juan P de Torres
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada
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11
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Neder JA, de-Torres JP, O'Donnell DE. Exposing Pre-Chronic Obstructive Pulmonary Disease: When Physiology Matters! Am J Respir Crit Care Med 2021; 204:110-111. [PMID: 33831329 PMCID: PMC8437111 DOI: 10.1164/rccm.202102-0474le] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- J Alberto Neder
- Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Juan Pablo de-Torres
- Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Denis E O'Donnell
- Queen's University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
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12
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Neder JA, de Torres JP, O'Donnell DE. Recent Advances in the Physiological Assessment of Dyspneic Patients with Mild COPD. COPD 2021; 18:374-384. [PMID: 33902376 DOI: 10.1080/15412555.2021.1913110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
There is growing recognition that a sizable fraction of COPD patients with forced expiratory volume in one second (FEV1)/forced vital capacity ratio below the lower limit of normal but preserved FEV1 reports out-of-proportion dyspnea relative to the severity of airflow limitation. Most physicians, however, assume that patients' breathlessness is unlikely to reflect the negative physiological consequences of COPD vis-à-vis FEV1 normalcy. This concise review integrates the findings of recent studies which uncovered the key pathophysiological features shared by these patients: poor pulmonary gas exchange efficiency (increased "wasted" ventilation) and gas trapping. These abnormalities are associated with two well-known causes of exertional dyspnea: heightened ventilation relative to metabolic demand and critically low inspiratory reserves, respectively. From a clinical standpoint, a low diffusion capacity associated with increased residual volume (RV) and/or RV/total lung capacity ratio might uncover these disturbances, identifying the subset of patients in whom exertional dyspnea is causally related to "mild" COPD.
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Affiliation(s)
- J Alberto Neder
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada
| | - Juan P de Torres
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada
| | - Denis E O'Donnell
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada
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13
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Soumagne T, Guillien A, Roche N, Dalphin JC, Degano B. Never-smokers with occupational COPD have better exercise capacities and ventilatory efficiency than matched smokers with COPD. J Appl Physiol (1985) 2020; 129:1257-1266. [PMID: 33002379 DOI: 10.1152/japplphysiol.00306.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Chronic obstructive pulmonary disease (COPD) in never-smokers exposed to organic dusts is still poorly characterized. Therapeutic strategies in COPD are only evaluated in smoking-related COPD. Understanding how never-smokers with COPD behave during exercise is an important prerequisite for optimal management. The objective of this study was to compare physiological parameters measured during exercise between never-smokers with COPD exposed to organic dusts and patients with smoking-related COPD matched for age, sex, and severity of airway obstruction. Healthy control subjects were also studied. Dyspnea (Borg scale), exercise tolerance, and ventilatory constraints were assessed during incremental cycle cardiopulmonary exercise testing in COPD patients at mild to moderate stages [22 exposed to organic dusts: postbronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) z score -2.44 ± 0.72 and FEV1 z score -1.45 ± 0.78; 22 with smoking-related COPD: FEV1/FVC z score -2.45 ± 0.61 and FEV1 z score -1.43 ± 0.69] and 44 healthy control subjects (including 22 never-smokers). Despite the occurrence of similar significant dynamic hyperinflation, never-smoker COPD patients exposed to organic dusts had lower dyspnea ratings than those with smoking-related COPD. They also had better ventilatory efficiency, higher peak oxygen consumption and peak power output than smoking-related COPD patients, all these parameters being similar to control subjects. Differences in exercise capacity between the two COPD groups were mainly driven by better ventilatory efficiency stemming from preserved diffusion capacity. Never-smokers exposed to organic dusts with mild to moderate COPD have better exercise capacities, better ventilatory efficiency, and better diffusion capacity than matched patients with smoking-related COPD.NEW & NOTEWORTHY It is unknown whether or not never-smokers with chronic obstructive pulmonary disease (COPD) behave like their smoking counterparts during exercise. This is the first study showing that never-smokers with mild to moderate COPD [defined by a postbronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) < lower limit of normal] have preserved exercise capacities. They also have lower exertional dyspnea than patients with smoking-related COPD. This suggests that the two COPD groups should not be managed in the same way.
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Affiliation(s)
- Thibaud Soumagne
- Service de Pneumologie, Oncologie Thoracique et Allergologie Respiratoire, CHU de Besançon, Besançon, France
| | - Alicia Guillien
- Equipe d'Epidémiologie Environnementale, Institute for Advanced Biosciences, Centre de Recherche UGA, INSERM U1209, CNRS UMR 5309, Grenoble, France
| | - Nicolas Roche
- Service de Pneumologie, Hôpital Cochin, AP-HP, Institut Cochin (UMR1016) et Université de Paris, Paris, France
| | - Jean-Charles Dalphin
- Service de Pneumologie, Oncologie Thoracique et Allergologie Respiratoire, CHU de Besançon, Besançon, France.,UMR CNRS Chrono Environnement, Université de Franche-Comté, Besançon, France
| | - Bruno Degano
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, CHU Grenoble Alpes, Grenoble, France.,HP2, INSERM U1042, Université Grenoble Alpes, Grenoble, France
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14
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Phillips DB, Collins SÉ, Stickland MK. Measurement and Interpretation of Exercise Ventilatory Efficiency. Front Physiol 2020; 11:659. [PMID: 32714201 PMCID: PMC7344219 DOI: 10.3389/fphys.2020.00659] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/25/2020] [Indexed: 12/19/2022] Open
Abstract
Cardiopulmonary exercise testing (CPET) is a method for evaluating pulmonary and cardiocirculatory abnormalities, dyspnea, and exercise tolerance in healthy individuals and patients with chronic conditions. During exercise, ventilation (V˙E) increases in proportion to metabolic demand [i.e., carbon dioxide production (V˙CO2)] to maintain arterial blood gas and acid-base balance. The response of V˙E relative to V˙CO2 (V˙E/V˙CO2) is commonly termed ventilatory efficiency and is becoming a common physiological tool, in conjunction with other key variables such as operating lung volumes, to evaluate exercise responses in patients with chronic conditions. A growing body of research has shown that the V˙E/V˙CO2 response to exercise is elevated in conditions such as chronic heart failure (CHF), pulmonary hypertension (PH), interstitial lung disease (ILD), and chronic obstructive pulmonary disease (COPD). Importantly, this potentiated V˙E/V˙CO2 response contributes to dyspnea and exercise intolerance. The clinical significance of ventilatory inefficiency is demonstrated by findings showing that the elevated V˙E/V˙CO2 response to exercise is an independent predictor of mortality in patients with CHF, PH, and COPD. In this article, the underlying physiology, measurement, and interpretation of exercise ventilatory efficiency during CPET are reviewed. Additionally, exercise ventilatory efficiency in varying disease states is briefly discussed.
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Affiliation(s)
- Devin B Phillips
- Clinical Physiology Laboratory, Division of Pulmonary Medicine, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada.,Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Sophie É Collins
- Clinical Physiology Laboratory, Division of Pulmonary Medicine, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Michael K Stickland
- Clinical Physiology Laboratory, Division of Pulmonary Medicine, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada.,G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, AB, Canada
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15
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Neder JA, Berton DC, Muller PT, O'Donnell DE. Incorporating Lung Diffusing Capacity for Carbon Monoxide in Clinical Decision Making in Chest Medicine. Clin Chest Med 2020; 40:285-305. [PMID: 31078210 DOI: 10.1016/j.ccm.2019.02.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lung diffusing capacity for carbon monoxide (Dlco) remains the only noninvasive pulmonary function test to provide an integrated picture of gas exchange efficiency in human lungs. Due to its critical dependence on the accessible "alveolar" volume (Va), there remains substantial misunderstanding on the interpretation of Dlco and the diffusion coefficient (Dlco/Va ratio, Kco). This article presents the physiologic and methodologic foundations of Dlco measurement. A clinically friendly approach for Dlco interpretation that takes those caveats into consideration is outlined. The clinical scenarios in which Dlco can effectively assist the chest physician are discussed and illustrative clinical cases are presented.
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Affiliation(s)
- J Alberto Neder
- Laboratory of Clinical Exercise Physiology, Division of Respirology and Sleep Medicine, Department of Medicine, Kingston Health Science Center, Queen's University, Richardson House, 102 Stuart Street, Kingston, Ontario K7L 2V6, Canada.
| | - Danilo C Berton
- Division of Respirology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Paulo T Muller
- Division of Respirology, Federal University of Mato Grosso do Sul, Campo Grande, Brazil
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Division of Respirology and Sleep Medicine, Kingston Health Science Center & Queen's University, Kingston, Ontario, Canada
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16
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Elbehairy AF, O'Donnell CD, Abd Elhameed A, Vincent SG, Milne KM, James MD, Webb KA, Neder JA, O’Donnell DE. Low resting diffusion capacity, dyspnea, and exercise intolerance in chronic obstructive pulmonary disease. J Appl Physiol (1985) 2019; 127:1107-1116. [DOI: 10.1152/japplphysiol.00341.2019] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanisms linking reduced diffusing capacity of the lung for carbon monoxide (DlCO) to dyspnea and exercise intolerance across the chronic obstructive pulmonary disease (COPD) continuum are poorly understood. COPD progression generally involves both DlCO decline and worsening respiratory mechanics, and their relative contribution to dyspnea has not been determined. In a retrospective analysis of 300 COPD patients who completed symptom-limited incremental cardiopulmonary exercise tests, we tested the association between peak oxygen-uptake (V̇o2), DlCO, and other resting physiological measures. Then, we stratified the sample into tertiles of forced expiratory volume in 1 s (FEV1) and inspiratory capacity (IC) and compared dyspnea ratings, pulmonary gas exchange, and respiratory mechanics during exercise in groups with normal and low DlCO [i.e., <lower limit of normal (LLN)] using Global Lung Function Initiative reference values. DlCO was associated with peak V̇o2 ( P = 0.006), peak work-rate ( P = 0.005), and dyspnea/V̇o2 slope ( P < 0.001) after adjustment for other independent variables (airway obstruction and hyperinflation). Within FEV1 and IC tertiles, peak V̇o2 and work rate were lower ( P < 0.05) in low versus normal DlCO groups. Across all tertiles, low DlCO groups had higher dyspnea ratings, greater ventilatory inefficiency and arterial oxygen desaturation, and showed greater mechanical volume constraints at a lower ventilation during exercise than the normal DlCO group (all P < 0.05). After accounting for baseline resting respiratory mechanical abnormalities, DlCO<LLN was consistently associated with greater dyspnea and poorer exercise performance compared with preserved DlCO. The higher dyspnea ratings and earlier exercise termination in low DlCO groups were linked to significantly greater pulmonary gas exchange abnormalities, higher ventilatory demand, and associated accelerated dynamic mechanical constraints. NEW & NOTEWORTHY Our study demonstrated that chronic obstructive pulmonary disease patients with diffusing capacity of the lung for carbon monoxide (DlCO) less than the lower limit of normal had greater pulmonary gas exchange abnormalities, which resulted in higher ventilatory demand and greater dynamic mechanical constraints at lower ventilation during exercise. This, in turn, led to greater exertional dyspnea and exercise intolerance compared with patients with normal DlCO.
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Affiliation(s)
- Amany F. Elbehairy
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Conor D. O'Donnell
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Asmaa Abd Elhameed
- Department of Biomedical Informatics and Medical Statistics, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Sandra G. Vincent
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Kathryn M. Milne
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Clinician Investigator Program, Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Matthew D. James
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Katherine A. Webb
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - J. Alberto Neder
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Denis E. O’Donnell
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
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17
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Balasubramanian A, MacIntyre NR, Henderson RJ, Jensen RL, Kinney G, Stringer WW, Hersh CP, Bowler RP, Casaburi R, Han MK, Porszasz J, Barr RG, Make BJ, Wise RA, McCormack MC. Diffusing Capacity of Carbon Monoxide in Assessment of COPD. Chest 2019; 156:1111-1119. [PMID: 31352035 DOI: 10.1016/j.chest.2019.06.035] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Diffusing capacity of the lung for carbon monoxide (Dlco) is inconsistently obtained in patients with COPD, and the added benefit of Dlco testing beyond that of more common tools is unknown. OBJECTIVE The goal of this study was to determine whether lower Dlco is associated with increased COPD morbidity independent of emphysema assessed via spirometry and CT imaging. METHODS Data for 1,806 participants with COPD from the Genetic Epidemiology of COPD (COPDGene) study 5-year visit were analyzed, including pulmonary function testing, quality of life, symptoms, exercise performance, and exacerbation rates. Dlco percent predicted was primarily analyzed as a continuous variable and additionally categorized into four groups: (1) Dlco and FEV1 > 50% (reference); (2) only Dlco ≤ 50%; (3) only FEV1 ≤ 50%; and (4) both ≤ 50% predicted. Outcomes were modeled by using multivariable linear and negative binomial regression, including emphysema and FEV1 percent predicted among other confounders. RESULTS In multivariable analyses, every 10% predicted decrease in Dlco was associated with symptoms and quality of life (COPD Assessment Test, 0.53 [P < .001]; St. George's Respiratory Questionnaire, 1.67 [P < .001]; Medical Outcomes Study Short Form 36 Physical Function, -0.89 [P < .001]), exercise performance (6-min walk distance, -45.35 feet; P < .001), and severe exacerbation rate (rate ratio, 1.14; P < .001). When categorized, severe impairment in Dlco alone, FEV1 alone, or both Dlco and FEV1 were associated with significantly worse morbidity compared with the reference group (P < .05 for all outcomes). CONCLUSIONS Impairment in Dlco was associated with increased COPD symptoms, reduced exercise performance, and severe exacerbation risk even after accounting for spirometry and CT evidence of emphysema. These findings suggest that Dlco should be considered for inclusion in future multidimensional tools assessing COPD.
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Affiliation(s)
- Aparna Balasubramanian
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Neil R MacIntyre
- Division of Pulmonary and Critical Care Medicine, Duke University, Durham, NC
| | - Robert J Henderson
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Robert L Jensen
- Division of Pulmonary and Critical Care Medicine, University of Utah, Salt Lake City, UT
| | - Gregory Kinney
- Department of Epidemiology, Colorado School of Public Health, University of Colorado, Denver, CO
| | - William W Stringer
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA
| | - Craig P Hersh
- Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA
| | - Russell P Bowler
- Division of Pulmonary, Critical Care and Sleep Medicine, National Jewish Health, Denver, CO
| | - Richard Casaburi
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA
| | - MeiLan K Han
- Division of Pulmonary and Critical Care Medicine, University of Michigan, Ann Arbor, MI
| | - Janos Porszasz
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA
| | - R Graham Barr
- Department of Epidemiology, Columbia University, New York, NY
| | - Barry J Make
- Division of Pulmonary, Critical Care and Sleep Medicine, National Jewish Health, Denver, CO
| | - Robert A Wise
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD
| | - Meredith C McCormack
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD.
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18
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Muller PDT, Barbosa GW, O'Donnell DE, Neder JA. Cardiopulmonary and Muscular Interactions: Potential Implications for Exercise (In)tolerance in Symptomatic Smokers Without Chronic Obstructive Pulmonary Disease. Front Physiol 2019; 10:859. [PMID: 31354517 PMCID: PMC6635481 DOI: 10.3389/fphys.2019.00859] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 06/20/2019] [Indexed: 12/15/2022] Open
Abstract
Smoking and physical inactivity are important preventable causes of disability and early death worldwide. Reduced exercise tolerance has been described in smokers, even in those who do not fulfill the extant physiological criteria for chronic obstructive pulmonary disease (COPD) and are not particularly sedentary. In this context, it is widely accepted that exercise capacity depends on complex cardio-pulmonary interactions which support oxygen (O2) delivery to muscle mitochondria. Although peripheral muscular factors, O2 transport disturbances (including the effects of increased carboxyhemoglobin) and autonomic nervous system unbalance have been emphasized, other derangements have been more recently described, including early microscopic emphysema, pulmonary microvascular disease, ventilatory and gas exchange inefficiency, and left ventricular diastolic dysfunction. Using an integrative physiological approach, the present review summarizes the recent advances in knowledge on the effects of smoking on the lung-heart-muscle axis under the stress of exercise. Special attention is given to the mechanisms connecting physiological abnormalities such as early cardio-pulmonary derangements, inadequate oxygen delivery and utilization, and generalized bioenergetic disturbances at the muscular level with the negative sensations (sense of heightened muscle effort and breathlessness) that may decrease the tolerance of smokers to physical exercise. A deeper understanding of the systemic effects of smoking in subjects who did not (yet) show evidences of COPD and ischemic heart disease - two devastating smoking related diseases - might prove instrumental to fight their ever-growing burden.
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Affiliation(s)
- Paulo de Tarso Muller
- Laboratory of Respiratory Pathophysiology, Respiratory Division, Department of Medicine, Federal University of Mato Grosso do Sul, Campo Grande, Brazil
| | - Gisele Walter Barbosa
- Laboratory of Respiratory Pathophysiology, Respiratory Division, Department of Medicine, Federal University of Mato Grosso do Sul, Campo Grande, Brazil
| | - Denis E O'Donnell
- Laboratory of Clinical Exercise Physiology, Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, ON, Canada
| | - J Alberto Neder
- Laboratory of Clinical Exercise Physiology, Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, ON, Canada
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19
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O’Donnell DE, James MD, Milne KM, Neder JA. The Pathophysiology of Dyspnea and Exercise Intolerance in Chronic Obstructive Pulmonary Disease. Clin Chest Med 2019; 40:343-366. [DOI: 10.1016/j.ccm.2019.02.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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20
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Bell AS, Lawrence PJ, Singh D, Horsley A. Feasibility and challenges of using multiple breath washout in COPD. Int J Chron Obstruct Pulmon Dis 2018; 13:2113-2119. [PMID: 30022817 PMCID: PMC6044337 DOI: 10.2147/copd.s164285] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background Lung clearance index (LCI), derived from multiple-breath washout (MBW), is a well-established assessment of ventilation inhomogeneity in cystic fibrosis but has not been widely applied in other conditions characterized by heterogeneous airways disease, such as COPD. The aim of this study was to evaluate the sensitivity, repeatability, and practicality of LCI in patients with COPD. Methods Fifty-four COPD patients completed MBW using nitrogen as the washout tracer gas (MBWN2, measured using an Exhalyzer™ device), spirometry, and plethysmography. Twenty patients repeated MBWN2, MBWSF6 (using a separate Innocor™ gas analyzer to measure washout of the exogenous trace sulphur hexafluoride), and spirometry at a second visit ≥24 hours later. Results Mean (SD) COPD LCI measured by nitrogen washout (LCIN2) was 12.1 (2.2); mean (SD) LCI Z-score 5.8 (2.0). LCIN2 increased across Global Initiative for Obstructive Lung Disease stages 1 to 3 and was abnormal (Z-score >1.65) in all COPD patients, including those with forced expiratory volume in 1 second (FEV1) ≥80% predicted. LCI was repeatable (median intra-test coefficient of variation 4.1%) and reproducible (limits of agreement -1.8 to 1.6) after mean of 16 days. Functional residual capacity (FRC) measurements were significantly greater using nitrogen than SF6 or plethysmography: mean FRC measured by nitrogen washout (FRCN2) 139% predicted versus FRC measured by plethysmography 125% predicted, p<0.0001. Conclusion LCI is most suitable as a measure of early airways disease in COPD in those with well-preserved FEV1, with similar repeatability and limitations to that observed in cystic fibrosis. Using the Exhalyzer system to perform MBWN2, however, appeared to substantially over-read FRC. This discrepancy needs addressing before FRCN2 measurements made using this device can be reliably deployed.
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Affiliation(s)
- Alan S Bell
- The Medicines Evaluation Unit, Wythenshawe Hospital, Manchester, UK.,Division of Infection Immunity and Respiratory Medicine, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK,
| | | | - Dave Singh
- The Medicines Evaluation Unit, Wythenshawe Hospital, Manchester, UK.,Division of Infection Immunity and Respiratory Medicine, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK, .,Manchester Academic Health Science Centre, Manchester, UK,
| | - Alexander Horsley
- Division of Infection Immunity and Respiratory Medicine, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK, .,Manchester Academic Health Science Centre, Manchester, UK, .,Manchester Adult Cystic Fibrosis Centre, Manchester University NHS Foundation Trust, Manchester, UK,
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21
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Arjomandi M, Zeng S, Geerts J, Stiner RK, Bos B, van Koeverden I, Keene J, Elicker B, Blanc PD, Gold WM. Lung volumes identify an at-risk group in persons with prolonged secondhand tobacco smoke exposure but without overt airflow obstruction. BMJ Open Respir Res 2018; 5:e000284. [PMID: 29755755 PMCID: PMC5942438 DOI: 10.1136/bmjresp-2018-000284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 03/19/2018] [Indexed: 12/05/2022] Open
Abstract
Introduction Exposure to secondhand smoke (SHS) is associated with occult obstructive lung disease as evident by abnormal airflow indices representing small airway disease despite having preserved spirometry (normal forced expiratory volume in 1 s-to-forced vital capacity ratio, FEV1/FVC). The significance of lung volumes that reflect air trapping in the presence of preserved spirometry is unclear. Methods To investigate whether lung volumes representing air trapping could determine susceptibility to respiratory morbidity in people with SHS exposure but without spirometric chronic obstructive pulmonary disease, we examined a cohort of 256 subjects with prolonged occupational SHS exposure and preserved spirometry. We elicited symptom prevalence by structured questionnaires, examined functional capacity (maximum oxygen uptake, VO2max) by exercise testing, and estimated associations of those outcomes with air trapping (plethysmography-measured residual volume-to-total lung capacity ratio, RV/TLC), and progressive air trapping with exertion (increase in fraction of tidal breathing that is flow limited on expiration during exercise (per cent of expiratory flow limitation, %EFL)). Results RV/TLC was within the predicted normal limits, but was highly variable spanning 22%±13% and 16%±8% across the increments of FEV1/FVC and FEV1, respectively. Respiratory complaints were prevalent (50.4%) with the most common symptom being ≥2 episodes of cough per year (44.5%). Higher RV/TLC was associated with higher OR of reporting respiratory symptoms (n=256; r2=0.03; p=0.011) and lower VO2max (n=179; r2=0.47; p=0.013), and %EFL was negatively associated with VO2max (n=32; r2=0.40; p=0.017). Conclusions In those at risk for obstruction due to SHS exposure but with preserved spirometry, higher RV/TLC identifies a subgroup with increased respiratory symptoms and lower exercise capacity.
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Affiliation(s)
- Mehrdad Arjomandi
- Division of Pulmonary, Critical Care, Allergy and Immunology, and Sleep Medicine, Department of Medicine, University of California, San Francisco, California, USA.,Division of Occupational and Environmental Medicine; Department of Medicine, University of California, San Francisco, California, USA.,Department of Medicine, San Francisco Veterans Affairs Medical Center, San Francisco, California, USA
| | - Siyang Zeng
- Division of Pulmonary, Critical Care, Allergy and Immunology, and Sleep Medicine, Department of Medicine, University of California, San Francisco, California, USA.,Department of Medicine, San Francisco Veterans Affairs Medical Center, San Francisco, California, USA
| | - Jeroen Geerts
- Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rachel K Stiner
- Division of Pulmonary, Critical Care, Allergy and Immunology, and Sleep Medicine, Department of Medicine, University of California, San Francisco, California, USA.,Department of Medicine, San Francisco Veterans Affairs Medical Center, San Francisco, California, USA
| | - Bruce Bos
- Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Jason Keene
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado, Denver, Colorado, USA
| | - Brett Elicker
- Department of Medicine, Cardiovascular Research Institute, University of California, San Francisco, California, USA.,Department of Radiology, University of California, San Francisco, California, USA
| | - Paul D Blanc
- Division of Pulmonary, Critical Care, Allergy and Immunology, and Sleep Medicine, Department of Medicine, University of California, San Francisco, California, USA.,Department of Medicine, San Francisco Veterans Affairs Medical Center, San Francisco, California, USA.,Division of Occupational and Environmental Medicine; Department of Medicine, University of California, San Francisco, California, USA.,Department of Medicine, Cardiovascular Research Institute, University of California, San Francisco, California, USA
| | - Warren M Gold
- Division of Pulmonary, Critical Care, Allergy and Immunology, and Sleep Medicine, Department of Medicine, University of California, San Francisco, California, USA.,Department of Medicine, Cardiovascular Research Institute, University of California, San Francisco, California, USA
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22
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Acute bronchodilator therapy does not reduce wasted ventilation during exercise in COPD. Respir Physiol Neurobiol 2018; 252-253:64-71. [PMID: 29578103 DOI: 10.1016/j.resp.2018.03.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 03/17/2018] [Accepted: 03/21/2018] [Indexed: 10/17/2022]
Abstract
This randomized, double-blind, crossover study aimed to determine if acute treatment with inhaled bronchodilators, by improving regional lung hyperinflation and ventilation distribution, would reduce dead space-to-tidal volume ratio (VD/VT); thus contributing to improved exertional dyspnea in COPD. Twenty COPD patients (FEV1 = 50 ± 15% predicted; mean ± SD) performed pulmonary function tests and symptom-limited constant-work rate exercise at 75% peak-work rate (with arterialized capillary blood gases) after nebulized bronchodilator (BD; ipratropium 0.5mg + salbutamol 2.5 mg) or placebo (PL; normal saline). After BD versus PL: Functional residual capacity decreased by 0.4L (p = .0001). Isotime during exercise after BD versus PL (p < .05): dyspnea decreased: 1.2 ± 1.9 Borg-units; minute ventilation increased: 3.8 ± 5.5 L/min; IC increased: 0.24 ± 0.28 L and VT increased 0.19 ± 0.16 L. There was no significant difference in arterial CO2 tension or VD/VT, but alveolar ventilation increased by 3.8 ± 5.5 L/min (p = .02). Post-BD improvements in respiratory mechanics explained 51% of dyspnea reduction at a standardized exercise time. Bronchodilator-induced improvements in respiratory mechanics were not associated with reduced wasted ventilation - a residual contributory factor to exertional dyspnea during exercise in COPD.
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Zelt JT, Jones JH, Hirai DM, King TJ, Berton DC, Pyke KE, O'Donnell DE, Neder JA. Systemic vascular dysfunction is associated with emphysema burden in mild COPD. Respir Med 2018; 136:29-36. [PMID: 29501244 DOI: 10.1016/j.rmed.2018.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 12/22/2017] [Accepted: 01/11/2018] [Indexed: 01/07/2023]
Abstract
BACKGROUND Cardiovascular diseases play a major role in morbidity and mortality in the earlier stages of COPD. We hypothesized that systemic vascular dysfunction would be present even in patients who are currently considered at "low-risk" for negative cardiovascular outcomes, i.e., those with largely preserved FEV1, few exacerbations and only mild burden of respiratory symptoms (GOLD spirometric grade 1, clinical group A). METHODS 16 patients (FEV1 = 86 ± 13%) and 16 age- and gender-matched controls underwent measurements of: a) central arterial stiffness by pulse wave velocity, b) brachial flow-mediated dilation and c) forearm muscle oxygenation by near-infrared spectroscopy. Computed tomography quantified emphysema (% of low attenuation areas (LAA)) and airway disease. RESULTS Patients and controls were well matched for key clinical variables including co-morbidities burden. Thirteen patients presented with more than 5% LAA: emphysema extension was negatively related to transfer factor for carbon monoxide (TLCO) (r = -0.63; p = .01). Compared to controls, patients had higher central arterial stiffness, lower normalized (to shear stress) flow-mediated dilation, delayed time to peak flow-mediated dilation and poorer muscle oxygenation (p < .05). TLCO and emphysema, but not airway disease, were significantly related to each of these functional abnormalities (r values ranging from 0.51 to 0.66; p < .05). CONCLUSION Systemic vascular dysfunction is present in the earlier stages of COPD, particularly in patients with greater emphysema burden and low TLCO. Regardless FEV1, patients showing those structural and functional abnormalities might be at higher risk of negative events thereby deserving closer follow-up for early detection of cardiovascular disease.
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Affiliation(s)
- Joel T Zelt
- Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada
| | - Joshua H Jones
- Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada
| | - Daniel M Hirai
- Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada
| | - Trevor J King
- Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Danilo C Berton
- Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada; Division of Respirology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Kyra E Pyke
- Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit (RIU), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada
| | - J Alberto Neder
- Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada.
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Outcome of pulmonary rehabilitation in patients with COPD: Comparison between patients receiving exercise training and those receiving exercise training and CPAP. EGYPTIAN JOURNAL OF CHEST DISEASES AND TUBERCULOSIS 2017. [DOI: 10.1016/j.ejcdt.2017.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Magnussen H, Canepa M, Zambito PE, Brusasco V, Meinertz T, Rosenkranz S. What can we learn from pulmonary function testing in heart failure? Eur J Heart Fail 2017; 19:1222-1229. [DOI: 10.1002/ejhf.946] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/06/2017] [Accepted: 06/26/2017] [Indexed: 12/28/2022] Open
Affiliation(s)
- Helgo Magnussen
- Pulmonary Research Institute at Lung Clinic Grosshansdorf and Airway Research Center North; Member of the German Center for Lung Research; Grosshansdorf Germany
| | - Marco Canepa
- Department of Internal Medicine and Medical Specialties; University of Genoa, San Martino Hospital; Genoa Italy
| | | | - Vito Brusasco
- Department of Internal Medicine and Medical Specialties; University of Genoa, San Martino Hospital; Genoa Italy
| | | | - Stephan Rosenkranz
- Klinik III für Innere Medizin, Herzzentrum der Universität zu Köln, Cologne, and Cologne Cardiovascular Research Center (CCRC); Heart Center at the University of Cologne; Cologne Germany
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Ventilatory Inefficiency and Exertional Dyspnea in Early Chronic Obstructive Pulmonary Disease. Ann Am Thorac Soc 2017; 14:S22-S29. [DOI: 10.1513/annalsats.201612-1033fr] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Elbehairy AF, Parraga G, Webb KA, Neder JA, O’Donnell DE. Mild chronic obstructive pulmonary disease: why spirometry is not sufficient! Expert Rev Respir Med 2017; 11:549-563. [DOI: 10.1080/17476348.2017.1334553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Amany F. Elbehairy
- Department of Medicine, Queen’s University and Kingston General Hospital, Kingston, ON, Canada
- Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Grace Parraga
- Department of Medical Biophysics, Robarts Research Institute, Western University, London, Canada
| | - Katherine A. Webb
- Department of Medicine, Queen’s University and Kingston General Hospital, Kingston, ON, Canada
| | - J Alberto Neder
- Department of Medicine, Queen’s University and Kingston General Hospital, Kingston, ON, Canada
| | - Denis E. O’Donnell
- Department of Medicine, Queen’s University and Kingston General Hospital, Kingston, ON, Canada
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