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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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Ferguson ON, Mitchell RA, Schaeffer MR, Ramsook AH, Boyle KGPJM, Dhillon SS, Zhang J, Hind AS, Jensen D, Guenette JA. Physiological Factors Associated with Unsatisfied Inspiration at Peak Exercise in Healthy Adults. Med Sci Sports Exerc 2024; 56:1488-1494. [PMID: 38547388 DOI: 10.1249/mss.0000000000003437] [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: 07/16/2024]
Abstract
INTRODUCTION Contrary to common belief, a growing body of evidence suggests that unsatisfied inspiration (UI), an inherently uncomfortable quality of dyspnea, is experienced by ostensibly healthy adults during high-intensity exercise. Based on our understanding of the mechanisms of UI among people with chronic respiratory conditions, this analysis tested the hypothesis that the experience of UI at peak exercise in young, healthy adults reflects the combination of high ventilatory demand and critical inspiratory constraints. METHODS In a retrospective analysis design, data included 321 healthy individuals (129 females) aged 25 ± 5 yr. Data were collected during one visit to the laboratory, which included anthropometrics, spirometry, and an incremental cardiopulmonary cycling test to exhaustion. Metabolic and cardiorespiratory variables were measured at peak exercise, and qualitative descriptors of dyspnea at peak exercise were assessed using a list of 15 descriptor phrases. RESULTS Thirty-four percent of participants ( n = 109) reported sensations of UI at peak exercise. Compared with the non-UI group, the UI group achieved a significantly higher peak work rate (243 ± 77 vs 235 ± 69 W, P = 0.016, d = 0.10), rate of O 2 consumption (3.32 ± 1.02 vs 3.27 ± 0.96 L·min -1 , P = 0.018, d = 0.05), minute ventilation (120 ± 38 vs 116 ± 35 L·min -1 , P = 0.047, d = 0.11), and breathing frequency (50 ± 9 vs 47 ± 9 breaths per minute, P = 0.014, d = 0.33), while having a lower exercise-induced change (peak-baseline) in inspiratory capacity (0.07 ± 0.41 vs 0.20 ± 0.49 L, P = 0.023, d = 0.29). The inspiratory reserve volume to minute ventilation ratio at peak exercise was also lower in the UI versus non-UI group. Dyspnea intensity and unpleasantness ratings were significantly higher in the UI versus non-UI group at peak exercise (both P < 0.001). CONCLUSIONS Healthy individuals reporting UI at peak exercise have relatively greater inspiratory constraints compared with those who do not select UI.
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Affiliation(s)
| | | | | | | | | | - Satvir S Dhillon
- Centre for Heart Lung Innovation, Providence Research, The University of British Columbia and St. Paul's Hospital, Vancouver, BC, CANADA
| | - Julia Zhang
- Centre for Heart Lung Innovation, Providence Research, The University of British Columbia and St. Paul's Hospital, Vancouver, BC, CANADA
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Goh JT, Balmain BN, Tomlinson AR, MacNamara JP, Sarma S, Ritz T, Wakeham DJ, Brazile TL, Hynan LS, Levine BD, Babb TG. Respiratory symptom perception during exercise in patients with heart failure with preserved ejection fraction. Respir Physiol Neurobiol 2024; 325:104256. [PMID: 38583744 PMCID: PMC11088520 DOI: 10.1016/j.resp.2024.104256] [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: 11/21/2023] [Revised: 02/26/2024] [Accepted: 04/04/2024] [Indexed: 04/09/2024]
Abstract
We investigated whether central or peripheral limitations to oxygen uptake elicit different respiratory sensations and whether dyspnea on exertion (DOE) provokes unpleasantness and negative emotions in patients with heart failure with preserved ejection fraction (HFpEF). 48 patients were categorized based on their cardiac output (Q̇c)/oxygen uptake (V̇O2) slope and stroke volume (SV) reserve during an incremental cycling test. 15 were classified as centrally limited and 33 were classified as peripherally limited. Ratings of perceived breathlessness (RPB) and unpleasantness (RPU) were assessed (Borg 0-10 scale) during a 20 W cycling test. 15 respiratory sensations statements (1-10 scale) and 5 negative emotions statements (1-10) were subsequently rated. RPB (Central: 3.5±2.0 vs. Peripheral: 3.4±2.0, p=0.86), respiratory sensations, or negative emotions were not different between groups (p>0.05). RPB correlated (p<0.05) with RPU (r=0.925), "anxious" (r=0.610), and "afraid" (r=0.383). While DOE provokes elevated levels of negative emotions, DOE and respiratory sensations seem more related to a common mechanism rather than central and/or peripheral limitations in HFpEF.
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Affiliation(s)
- Josh T Goh
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bryce N Balmain
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Andrew R Tomlinson
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - James P MacNamara
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Thomas Ritz
- Department of Psychology, Southern Methodist University, Dallas, TX, USA
| | - Denis J Wakeham
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tiffany L Brazile
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Linda S Hynan
- The O'Donnell School of Public Health and Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tony G Babb
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Phillips DB, James MD, Vincent SG, Elbehairy AF, Neder JA, Kirby M, Ora J, Day AG, Tan WC, Bourbeau J, O'Donnell DE. Physiological Characterization of Preserved Ratio Impaired Spirometry in the CanCOLD Study: Implications for Exertional Dyspnea and Exercise Intolerance. Am J Respir Crit Care Med 2024; 209:1314-1327. [PMID: 38170674 DOI: 10.1164/rccm.202307-1184oc] [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: 07/11/2023] [Accepted: 01/03/2024] [Indexed: 01/05/2024] Open
Abstract
Rationale: It is increasingly recognized that adults with preserved ratio impaired spirometry (PRISm) are prone to increased morbidity. However, the underlying pathophysiological mechanisms are unknown. Objectives: Evaluate the mechanisms of increased dyspnea and reduced exercise capacity in PRISm. Methods: We completed a cross-sectional analysis of the CanCOLD (Canadian Cohort Obstructive Lung Disease) population-based study. We compared physiological responses in 59 participants meeting PRISm spirometric criteria (post-bronchodilator FEV1 < 80% predicted and FEV1/FVC ⩾ 0.7), 264 control participants, and 170 ever-smokers with chronic obstructive pulmonary disease (COPD), at rest and during cardiopulmonary exercise testing. Measurements and Main Results: Individuals with PRISm had lower total lung, vital, and inspiratory capacities than healthy controls (all P < 0.05) and minimal small airway, pulmonary gas exchange, and radiographic parenchymal lung abnormalities. Compared with healthy controls, individuals with PRISm had higher dyspnea/[Formula: see text]o2 ratio at peak exercise (4.0 ± 2.2 vs. 2.9 ± 1.9 Borg units/L/min; P < 0.001) and lower [Formula: see text]o2peak (74 ± 22% predicted vs. 96 ± 25% predicted; P < 0.001). At standardized submaximal work rates, individuals with PRISm had greater Vt/inspiratory capacity (Vt%IC; P < 0.001), reflecting inspiratory mechanical constraint. In contrast to participants with PRISm, those with COPD had characteristic small airways dysfunction, dynamic hyperinflation, and pulmonary gas exchange abnormalities. Despite these physiological differences among the three groups, the relationship between increasing dyspnea and Vt%IC during cardiopulmonary exercise testing was similar. Resting IC significantly correlated with [Formula: see text]o2peak (r = 0.65; P < 0.001) in the entire sample, even after adjusting for airflow limitation, gas trapping, and diffusing capacity. Conclusions: In individuals with PRISm, lower exercise capacity and higher exertional dyspnea than healthy controls were mainly explained by lower resting lung volumes and earlier onset of dynamic inspiratory mechanical constraints at relatively low work rates. Clinical trial registered with www.clinicaltrials.gov (NCT00920348).
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Affiliation(s)
- Devin B Phillips
- School of Kinesiology and Health Science, Faculty of Health, and
- Muscle Health Research Center, York University, Toronto, Ontario, Canada
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Site, Kingston, Ontario, Canada
| | - Matthew D James
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Site, Kingston, Ontario, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Site, Kingston, Ontario, Canada
| | - Amany F Elbehairy
- Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
- Division of Infection, Immunity, and Respiratory Medicine, The University of Manchester, and Manchester University NHS Foundation Trust, Manchester, United Kingdom
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Site, Kingston, Ontario, Canada
| | - Miranda Kirby
- Department of Physics, Toronto Metropolitan University, Toronto, Ontario, Canada
| | - Josuel Ora
- Division of Respiratory Medicine, University Hospital Policlinico Tor Vergata, Rome, Italy
| | - Andrew G Day
- Kingston General Hospital Research Institute, Kingston, Ontario, Canada
| | - Wan C Tan
- Centre for Heart Lung Innovation, Providence Health Care Research Institute, University of British Columbia, St. Paul's Hospital, Vancouver, British Columbia, Canada; and
| | - Jean Bourbeau
- Research Institute of the McGill University Health Centre, Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, and
- Division of Respiratory Medicine, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Site, Kingston, Ontario, Canada
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Elbehairy AF, Marshall H, Naish JH, Wild JM, Parraga G, Horsley A, Vestbo J. Advances in COPD imaging using CT and MRI: linkage with lung physiology and clinical outcomes. Eur Respir J 2024; 63:2301010. [PMID: 38548292 DOI: 10.1183/13993003.01010-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 03/16/2024] [Indexed: 05/04/2024]
Abstract
Recent years have witnessed major advances in lung imaging in patients with COPD. These include significant refinements in images obtained by computed tomography (CT) scans together with the introduction of new techniques and software that aim for obtaining the best image whilst using the lowest possible radiation dose. Magnetic resonance imaging (MRI) has also emerged as a useful radiation-free tool in assessing structural and more importantly functional derangements in patients with well-established COPD and smokers without COPD, even before the existence of overt changes in resting physiological lung function tests. Together, CT and MRI now allow objective quantification and assessment of structural changes within the airways, lung parenchyma and pulmonary vessels. Furthermore, CT and MRI can now provide objective assessments of regional lung ventilation and perfusion, and multinuclear MRI provides further insight into gas exchange; this can help in structured decisions regarding treatment plans. These advances in chest imaging techniques have brought new insights into our understanding of disease pathophysiology and characterising different disease phenotypes. The present review discusses, in detail, the advances in lung imaging in patients with COPD and how structural and functional imaging are linked with common resting physiological tests and important clinical outcomes.
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Affiliation(s)
- Amany F Elbehairy
- Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
- Division of Infection, Immunity and Respiratory Medicine, The University of Manchester and Manchester University NHS Foundation Trust, Manchester Academic Health Sciences Centre, Manchester, UK
| | - Helen Marshall
- POLARIS, Imaging, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Josephine H Naish
- MCMR, Manchester University NHS Foundation Trust, Manchester, UK
- Bioxydyn Limited, Manchester, UK
| | - Jim M Wild
- POLARIS, Imaging, Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
- Insigneo Institute for in silico Medicine, Sheffield, UK
| | - Grace Parraga
- Robarts Research Institute, Western University, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
- Division of Respirology, Western University, London, ON, Canada
| | - Alexander Horsley
- Division of Infection, Immunity and Respiratory Medicine, The University of Manchester and Manchester University NHS Foundation Trust, Manchester Academic Health Sciences Centre, Manchester, UK
| | - Jørgen Vestbo
- Division of Infection, Immunity and Respiratory Medicine, The University of Manchester and Manchester University NHS Foundation Trust, Manchester Academic Health Sciences Centre, Manchester, UK
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Brotto AR, Phillips DB, Rowland SD, Moore LE, Wong E, Stickland MK. Reduced tidal volume-inflection point and elevated operating lung volumes during exercise in females with well-controlled asthma. BMJ Open Respir Res 2023; 10:e001791. [PMID: 38135461 DOI: 10.1136/bmjresp-2023-001791] [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: 04/24/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
INTRODUCTION Individuals with asthma breathe at higher operating lung volumes during exercise compared with healthy individuals, which contributes to increased exertional dyspnoea. In health, females are more likely to develop exertional dyspnoea than males at a given workload or ventilation, and therefore, it is possible that females with asthma may develop disproportional dyspnoea on exertion. The purpose of this study was to compare operating lung volume and dyspnoea responses during exercise in females with and without asthma. METHODS Sixteen female controls and 16 females with asthma were recruited for the study along with 16 male controls and 16 males with asthma as a comparison group. Asthma was confirmed using American Thoracic Society criteria. Participants completed a cycle ergometry cardiopulmonary exercise test to volitional exhaustion. Inspiratory capacity manoeuvres were performed to estimate inspiratory reserve volume (IRV) and dyspnoea was evaluated using the Modified Borg Scale. RESULTS Females with asthma exhibited elevated dyspnoea during submaximal exercise compared with female controls (p<0.05). Females with asthma obtained a similar IRV and dyspnoea at peak exercise compared with healthy females despite lower ventilatory demand, suggesting mechanical constraint to tidal volume (VT) expansion. VT-inflection point was observed at significantly lower ventilation and V̇O2 in females with asthma compared with female controls. Forced expired volume in 1 s was significantly associated with VT-inflection point in females with asthma (R2=0.401; p<0.01) but not female controls (R2=0.002; p=0.88). CONCLUSION These results suggest that females with asthma are more prone to experience exertional dyspnoea, secondary to dynamic mechanical constraints during submaximal exercise when compared with females without asthma.
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Affiliation(s)
- Andrew R Brotto
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Devin B Phillips
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, Ontario, Canada
| | - Samira D Rowland
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Linn E Moore
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Eric Wong
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Michael K Stickland
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Sietsema KE, Rossiter HB. Exercise Physiology and Cardiopulmonary Exercise Testing. Semin Respir Crit Care Med 2023; 44:661-680. [PMID: 37429332 DOI: 10.1055/s-0043-1770362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
Aerobic, or endurance, exercise is an energy requiring process supported primarily by energy from oxidative adenosine triphosphate synthesis. The consumption of oxygen and production of carbon dioxide in muscle cells are dynamically linked to oxygen uptake (V̇O2) and carbon dioxide output (V̇CO2) at the lung by integrated functions of cardiovascular, pulmonary, hematologic, and neurohumoral systems. Maximum oxygen uptake (V̇O2max) is the standard expression of aerobic capacity and a predictor of outcomes in diverse populations. While commonly limited in young fit individuals by the capacity to deliver oxygen to exercising muscle, (V̇O2max) may become limited by impairment within any of the multiple systems supporting cellular or atmospheric gas exchange. In the range of available power outputs, endurance exercise can be partitioned into different intensity domains representing distinct metabolic profiles and tolerances for sustained activity. Estimates of both V̇O2max and the lactate threshold, which marks the upper limit of moderate-intensity exercise, can be determined from measures of gas exchange from respired breath during whole-body exercise. Cardiopulmonary exercise testing (CPET) includes measurement of V̇O2 and V̇CO2 along with heart rate and other variables reflecting cardiac and pulmonary responses to exercise. Clinical CPET is conducted for persons with known medical conditions to quantify impairment, contribute to prognostic assessments, and help discriminate among proximal causes of symptoms or limitations for an individual. CPET is also conducted in persons without known disease as part of the diagnostic evaluation of unexplained symptoms. Although CPET quantifies a limited sample of the complex functions and interactions underlying exercise performance, both its specific and global findings are uniquely valuable. Some specific findings can aid in individualized diagnosis and treatment decisions. At the same time, CPET provides a holistic summary of an individual's exercise function, including effects not only of the primary diagnosis, but also of secondary and coexisting conditions.
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Affiliation(s)
- Kathy E Sietsema
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, Torrance, California
| | - Harry B Rossiter
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, Torrance, California
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Illidi CR, Romer LM, Johnson MA, Williams NC, Rossiter HB, Casaburi R, Tiller NB. Distinguishing science from pseudoscience in commercial respiratory interventions: an evidence-based guide for health and exercise professionals. Eur J Appl Physiol 2023; 123:1599-1625. [PMID: 36917254 PMCID: PMC10013266 DOI: 10.1007/s00421-023-05166-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/19/2023] [Indexed: 03/16/2023]
Abstract
Respiratory function has become a global health priority. Not only is chronic respiratory disease a leading cause of worldwide morbidity and mortality, but the COVID-19 pandemic has heightened attention on respiratory health and the means of enhancing it. Subsequently, and inevitably, the respiratory system has become a target of the multi-trillion-dollar health and wellness industry. Numerous commercial, respiratory-related interventions are now coupled to therapeutic and/or ergogenic claims that vary in their plausibility: from the reasonable to the absurd. Moreover, legitimate and illegitimate claims are often conflated in a wellness space that lacks regulation. The abundance of interventions, the range of potential therapeutic targets in the respiratory system, and the wealth of research that varies in quality, all confound the ability for health and exercise professionals to make informed risk-to-benefit assessments with their patients and clients. This review focuses on numerous commercial interventions that purport to improve respiratory health, including nasal dilators, nasal breathing, and systematized breathing interventions (such as pursed-lips breathing), respiratory muscle training, canned oxygen, nutritional supplements, and inhaled L-menthol. For each intervention we describe the premise, examine the plausibility, and systematically contrast commercial claims against the published literature. The overarching aim is to assist health and exercise professionals to distinguish science from pseudoscience and make pragmatic and safe risk-to-benefit decisions.
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Affiliation(s)
- Camilla R Illidi
- Clinical Exercise and Respiratory Physiology Laboratory, Department of Kinesiology and Physical Education, Faculty of Education, McGill University, Montréal, QC, Canada
| | - Lee M Romer
- Division of Sport, Health and Exercise Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, UK
| | - Michael A Johnson
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, Nottinghamshire, UK
| | - Neil C Williams
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, Nottinghamshire, UK
| | - Harry B Rossiter
- Institute of Respiratory Medicine and Exercise Physiology, Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson Street, CDCRC Building, Torrance, CA, 90502, USA
| | - Richard Casaburi
- Institute of Respiratory Medicine and Exercise Physiology, Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson Street, CDCRC Building, Torrance, CA, 90502, USA
| | - Nicholas B Tiller
- Institute of Respiratory Medicine and Exercise Physiology, Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson Street, CDCRC Building, Torrance, CA, 90502, USA.
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Neder JA. Cardiopulmonary exercise testing applied to respiratory medicine: Myths and facts. Respir Med 2023; 214:107249. [PMID: 37100256 DOI: 10.1016/j.rmed.2023.107249] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/28/2023] [Accepted: 04/18/2023] [Indexed: 04/28/2023]
Abstract
Cardiopulmonary exercise testing (CPET) remains poorly understood and, consequently, largely underused in respiratory medicine. In addition to a widespread lack of knowledge of integrative physiology, several tenets of CPET interpretation have relevant controversies and limitations which should be appropriately recognized. With the intent to provide a roadmap for the pulmonologist to realistically calibrate their expectations towards CPET, a collection of deeply entrenched beliefs is critically discussed. They include a) the actual role of CPET in uncovering the cause(s) of dyspnoea of unknown origin, b) peak O2 uptake as the key metric of cardiorespiratory capacity, c) the value of low lactate ("anaerobic") threshold to differentiate cardiocirculatory from respiratory causes of exercise limitation, d) the challenges of interpreting heart rate-based indexes of cardiovascular performance, e) the meaning of peak breathing reserve in dyspnoeic patients, f) the merits and drawbacks of measuring operating lung volumes during exercise, g) how best interpret the metrics of gas exchange inefficiency such as the ventilation-CO2 output relationship, h) when (and why) measurements of arterial blood gases are required, and i) the advantages of recording submaximal dyspnoea "quantity" and "quality". Based on a conceptual framework that links exertional dyspnoea to "excessive" and/or "restrained" breathing, I outline the approaches to CPET performance and interpretation that proved clinically more helpful in each of these scenarios. CPET to answer clinically relevant questions in pulmonology is a largely uncharted research field: I, therefore, finalize by highlighting some lines of inquiry to improve its diagnostic and prognostic yield.
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Affiliation(s)
- J Alberto Neder
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Department of Medicine, Division of Respirology, Kingston Health Sciences Center, Queen's University, Kingston, ON, Canada.
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10
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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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James MD, Phillips DB, Vincent SG, Abdallah SJ, Donovan AA, de-Torres JP, Neder JA, Smith BM, Jensen D, O'Donnell DE. Exertional dyspnoea in patients with mild-to-severe chronic obstructive pulmonary disease (COPD): Neuromechanical mechanisms. J Physiol 2022; 600:4227-4245. [PMID: 35861594 DOI: 10.1113/jp283252] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/11/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Dyspnoea during exercise is a common and troublesome symptom reported by patients with chronic obstructive pulmonary disease (COPD) and is linked to an elevated inspiratory neural drive (IND). The precise mechanisms of elevated IND and dyspnoea across the continuum of airflow obstruction severity in COPD remains unclear. The present study sought to determine the mechanisms of elevated IND [by diaphragm EMG, EMGdi (%max)] and dyspnoea during cardiopulmonary exercise testing (CPET) across the continuum of COPD severity. There was a strong association between increasing dyspnoea intensity and EMGdi (%max) during CPET across the COPD continuum despite significant heterogeneity in underlying pulmonary gas exchange and respiratory mechanical impairments. Critical inspiratory constraints occurred at progressively lower ventilation during exercise with worsening severity of COPD. This was associated with the progressively lower resting inspiratory capacity with worsening disease severity. Earlier critical inspiratory constraint was associated with earlier neuromechanical dissociation and greater likelihood of reporting the sensation of 'unsatisfied inspiration'. ABSTRACT In patients with COPD, exertional dyspnoea generally arises when there is imbalance between ventilatory demand and capacity, but the neurophysiological mechanisms are unclear. We therefore determined if disparity between elevated inspiratory neural drive (IND) and tidal volume (VT ) responses (neuromechanical dissociation) impacted dyspnoea intensity and quality during exercise, across the COPD severity spectrum. In this two-centre, cross-sectional observational study, 89 participants with COPD divided into tertiles of FEV1 %predicted (Tertile 1 = FEV1 = 87 ± 9%, Tertile 2 = 60 ± 9%, Tertile 3 = 32 ± 8%) and 18 non-smoking controls, completed a symptom-limited cardiopulmonary exercise tests (CPET) with measurement of IND by diaphragm electromyography [EMGdi (%max)]. The association between increasing dyspnoea intensity and EMGdi (%max) during CPET was strong (r = 0.730, P < 0.001) and not different between the four groups who showed marked heterogeneity in pulmonary gas exchange and mechanical abnormalities. Significant inspiratory constraints (tidal volume/inspiratory capacity (VT /IC) ≥ 70%) and onset of neuromechanical dissociation (EMGdi (%max):VT /IC > 0.75) occurred at progressively lower V̇E from Control to Tertile 3. Lower resting IC meant earlier onset of neuromechanical dissociation, heightened dyspnoea intensity and greater propensity (93% in Tertile 3) to select qualitative descriptors of 'unsatisfied inspiration'. We concluded that, regardless of marked variation in mechanical and pulmonary gas exchange abnormalities in our study sample, exertional dyspnoea intensity was linked to the magnitude of EMGdi (%max). Moreover, onset of critical inspiratory constraints and attendant neuromechanical dissociation amplified dyspnoea intensity at higher exercise intensities. Simple measurements of IC and breathing pattern during CPET provide useful insights into mechanisms of dyspnoea and exercise intolerance in individuals with COPD. Abstract figure legend As chronic obstructive pulmonary disease severity increases, worsening gas exchange and respiratory mechanical impairment causes increased afferent receptor stimulation, increasing inspiratory neural drive at a given ventilation. The widening disparity between progressively greater inspiratory neural drive and reduced ventilatory output causes, 'neuromechanical dissociation'. This is strongly associated with a rapid increase in the intensity of dyspnea during exercise, and the onset of the sensation of 'unsatisfied inspiration'. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Matthew D James
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Sara J Abdallah
- Clinical Exercise and Respiratory Physiology Laboratory, Department of Kinesiology and Physical Education, Faculty of Education, McGill University, Montréal, Quebec, Canada.,Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Adamo A Donovan
- Division of Respiratory Medicine, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Juan P de-Torres
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Benjamin M Smith
- Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada.,Division of Respiratory Medicine, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Dennis Jensen
- Clinical Exercise and Respiratory Physiology Laboratory, Department of Kinesiology and Physical Education, Faculty of Education, McGill University, Montréal, Quebec, Canada.,Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
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- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
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