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Huang YCT, Henriquez L, Chen H, Henriquez C. Development and evaluation of a computerized algorithm for the interpretation of pulmonary function tests. PLoS One 2024; 19:e0297519. [PMID: 38285673 PMCID: PMC10824436 DOI: 10.1371/journal.pone.0297519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 01/07/2024] [Indexed: 01/31/2024] Open
Abstract
Pulmonary function tests (PFTs) are usually interpreted by clinicians using rule-based strategies and pattern recognition. The interpretation, however, has variabilities due to patient and interpreter errors. Most PFTs have recognizable patterns that can be categorized into specific physiological defects. In this study, we developed a computerized algorithm using the python package (pdfplumber) and validated against clinicians' interpretation. We downloaded PFT reports in the electronic medical record system that were in PDF format. We digitized the flow volume loop (FVL) and extracted numeric values from the reports. The algorithm used FEV1/FVC<0.7 for obstruction, TLC<80%pred for restriction and <80% or >120%pred for abnormal DLCO. The algorithm also used a small airway disease index (SADI) to quantify late expiratory flattening of the FVL to assess small airway dysfunction. We devised keywords for the python Natural Language Processing (NLP) package (spaCy) to identify obstruction, restriction, abnormal DLCO and small airway dysfunction in the reports. The algorithm was compared to clinicians' interpretation in 6,889 PFTs done between March 1st, 2018, and September 30th, 2020. The agreement rates (Cohen's kappa) for obstruction, restriction and abnormal DLCO were 94.4% (0.868), 99.0% (0.979) and 87.9% (0.750) respectively. In 4,711 PFTs with FEV1/FVC≥0.7, the algorithm identified 190 tests with SADI < lower limit of normal (LLN), suggesting small airway dysfunction. Of these, the clinicians (67.9%) also flagged 129 tests. When SADI was ≥ LLN, no clinician's reports indicated small airway dysfunction. Our results showed the computerized algorithm agreed with clinicians' interpretation in approximately 90% of the tests and provided a sensitive objective measure for assessing small airway dysfunction. The algorithm can improve efficiency and consistency and decrease human errors in PFT interpretation. The computerized algorithm works directly on PFT reports in PDF format and can be adapted to incorporate a different interpretation strategy and platform.
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Affiliation(s)
- Yuh-Chin T. Huang
- Department of Medicine, Duke University Medical Center, Durham, NC, United States of America
| | - Luke Henriquez
- Department of Cognitive Science, Case Western University, Cleveland, OH, United States of America
| | - Hengji Chen
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States of America
| | - Craig Henriquez
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States of America
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Lin CH, Johnson LR, Chang WT, Lo PY, Chen HW, Wu HD. Quantifiable features of a tidal breathing phenotype in dogs with severe bronchomalacia diagnosed by bronchoscopy. Vet Q 2023; 43:1-10. [PMID: 37616027 PMCID: PMC10478619 DOI: 10.1080/01652176.2023.2252518] [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: 05/24/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 08/25/2023] Open
Abstract
Dynamic lower airway obstruction is the primary component of canine bronchomalacia, but the ventilatory function remains underinvestigated. This prospective study analyzed tidal breathing characteristics in 28 dogs, comprising 14 with severe bronchomalacia diagnosed by bronchoscopy versus 14 without respiratory disease. Spirometry was conducted in all dogs. Bronchoscopy with bronchoalveolar lavage or brush under anesthesia was performed in 14 dogs with cough and expiratory effort. Severe bronchomalacia was defined by the severity of collapse and total number of bronchi affected. Ventilatory characteristics were compared between groups. Results revealed that dogs with severe bronchomalacia had lower minute volume (218 vs 338 mL/kg, p = .039) and greater expiratory-to-inspiratory time ratio (1.55 vs 1.35, p = .01) compared to control dogs. The tidal breathing pattern of dogs with bronchomalacia was different from that of normal dogs, and the pattern differed from the concave or flat expiratory curves typical of lower airway obstruction. Compared to control dogs, dogs with severe bronchomalacia had a significantly prolonged low-flow expiratory phase (p < .001) on the flow-time plot and a more exponential shape of the expiratory curve (p < .001) on the volume-time plot. Flow-time index ExpLF/Te (>0.14) and volume-time index Vt-AUCexp (≤31%) had a high ROC-AUC (1.00, 95% confidence interval 0.88 to 1.00) in predicting severe bronchomalacia. In conclusion, the tidal breathing pattern identified here indicates abnormal and complicated ventilatory mechanics in dogs with severe bronchomalacia. The role of this pulmonary functional phenotype should be investigated for disease progression and therapeutic monitoring in canine bronchomalacia.
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Affiliation(s)
- Chung-Hui Lin
- National Taiwan University Veterinary Hospital, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Veterinary Clinical Sciences, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
- TACS-Alliance Research Center, Taipei, Taiwan
| | - Lynelle R. Johnson
- Department of Medicine and Epidemiology, The University of California School of Veterinary Medicine, Davis, CA, USA
| | - Wei-Tao Chang
- National Taiwan University Veterinary Hospital, National Taiwan University, Taipei, Taiwan
- TACS-Alliance Research Center, Taipei, Taiwan
| | - Pei-Ying Lo
- TACS-Alliance Research Center, Taipei, Taiwan
| | - Hui-Wen Chen
- Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Huey-Dong Wu
- Section of Respiratory Therapy, Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, National Taiwan University, Taipei, Taiwan
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Porszasz J, Wang CY, Ferguson C, Ma S, Girardi M, Stringer WW. Letter to the editor in response to Hoskote "Corrected formula for rectangular area ratio (RAR), a parameter used to quantify airflow limitation on expiratory flow-volume curves" Respiratory Medicine 2022; 204: 107032. Respir Med 2023:107304. [PMID: 37257784 DOI: 10.1016/j.rmed.2023.107304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 05/27/2023] [Indexed: 06/02/2023]
Affiliation(s)
- Janos Porszasz
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson St. Torrance, CA, 90502, USA.
| | - Chu-Yi Wang
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson St. Torrance, CA, 90502, USA
| | - Carrie Ferguson
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson St. Torrance, CA, 90502, USA
| | - Shuyi Ma
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson St. Torrance, CA, 90502, USA
| | - Michele Girardi
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson St. Torrance, CA, 90502, USA
| | - William W Stringer
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, 1124 W. Carson St. Torrance, CA, 90502, USA
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Lukacsovits J, Szollosi G, Varga JT. Cardiovascular effects of exercise induced dynamic hyperinflation in COPD patients-Dynamically hyperinflated and non-hyperinflated subgroups. PLoS One 2023; 18:e0274585. [PMID: 36662787 PMCID: PMC9858323 DOI: 10.1371/journal.pone.0274585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 08/29/2022] [Indexed: 01/21/2023] Open
Abstract
INTRODUCTION An increase in respiratory rate and expiratory flow limitation can facilitate dynamic hyperinflation (DH), which may cause an element of the intrathoracic pressure in connection with the worsening of venous return, with negative effect on stroke volume (SV) and cardiac output (CO). It has been unclassified, whether poor circulatory adaptation to exercise can be attributed to DH or poor cardio-vascular performance itself in COPD. Only a subset of COPD patients exhibit dynamic hyperinflation during exercise. PATIENTS AND METHODS We designed a study to show how lung mechanical and cardiovascular parameters change in hyperinflated and non-hyperinflated COPD patients during exercise with a new experimental set-up. Thirty-three COPD patients with similar severity of COPD and left ventricular performance (20 men, 13 women, mean±SD age: 65,36±6,95 years) participated. We measured the cardiovascular parameters with a non-invasive device (Finometer-pro) including the left ventricular ejection time index (LVETi) and estimated the change of DH with inspiratory capacity (IC) manoeuvres during exercise. RESULTS Twenty-one subjects exhibited DH (DH group) and 12 did not (non-DH group). The measurement results were given in mean ± SD and difference between the values measured during maximal load and rest also (ΔX = Xmax.load-Xrest). ΔSV and ΔCO were significantly higher in non-DH vs. DH patients (ΔSV: non-DH 9,7 ± 13,22 ml vs. DH -3,6 ± 14,34 ml, p = 0.0142; ΔCO: non-DH 2,26 ± 1,46 l/min vs. DH 0,88 ± 1,35 l/min, p = 0.0024). LVETi was not different between the two groups. Calculated oxygen delivery (DO2) during maximal load was significantly higher in non-DH group. CONCLUSION We concluded that worse cardiovascular adaptation to exercise of COPD patients can be associated with exercise-induced DH in a similar cardiovascular aged COPD group.
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Affiliation(s)
| | - Gergo Szollosi
- Department of Interventional Epidemiology, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
| | - Janos T. Varga
- Department of Pulmonology, Semmelweis University, Budapest, Hungary
- Department of Pulmonary Rehabilitation, National Koranyi Institute of Pulmonology, Budapest, Hungary
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Hoskote SS. Corrected formula for rectangular area ratio (RAR), a parameter used to quantify airflow limitation on expiratory flow-volume curves. Respir Med 2022; 204:107032. [DOI: 10.1016/j.rmed.2022.107032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022]
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Csizmadia Z, Ács P, Szőllősi GJ, Tóth B, Kerti M, Kovács A, Varga JT. Freedive Training Gives Additional Physiological Effect Compared to Pulmonary Rehabilitation in COPD. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:11549. [PMID: 36141823 PMCID: PMC9517084 DOI: 10.3390/ijerph191811549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
INTRODUCTION Pulmonary rehabilitation (PR) is beneficial for lung mechanics, chest kinematics, metabolism, and inspiratory and peripheral muscle function. Freediving training (FD) can be effective in sportsmen and can improve breath-holding time. AIMS We sought to determine the effectiveness of freediving training in the pulmonary rehabilitation of COPD patients. PATIENTS AND METHODS Twenty-three COPD patients (15 men and 8 women; median age 63 years; FEV1: 41% pred; BMI: 28 kg/m2) participated in the FD + PR group (3 weeks PR and 3 weeks FD + PR) and 46 patients with COPD (25 men and 21 women; median age 66 years; FEV1: 43% pred; BMI: 27 kg/m2) participated in an inpatient PR program (6 weeks). Patients performed comfort zone breath holding for 30 min/day. Patients increased their breath-holding time within their comfort zone for 30 min. We detected lung function, chest expansion (CWE), inspiratory muscle pressure (MIP), peripheral muscle function (GS), and exercise capacity (6MWD), and we included breath-holding time (BHT), quality of life score (COPD Assessment Test (CAT)), modified Medical Research Dyspnea Scale (mMRC) score, and the severity of the disease assessed by the BODE index (FEV1, BMI, 6MWD, and mMRC) and an alternative scale (FEV1, BMI, 6MWD, and CAT). RESULT There were significant differences in the characteristics of the two groups. Significant improvement was detected in all functional and quality of life parameters except lung function in both groups. Significantly higher improvement was detected in CWE, GS, 6MWD, BHT, CAT, mMRC, alternative scale, and MIP. The improvement in forced vital capacity (FVC) was not significant. There were no side effects of FD training. CONCLUSION The FD method can potentiate the effect of PR, improving not only BHT but also other parameters. TRIAL REGISTRATION ISRCTN ISRCTN13019180. Registered 19 December 2017.
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Affiliation(s)
- Zoltán Csizmadia
- Faculty of Health Sciences, University of Pécs, 7621 Pécs, Hungary
| | - Pongrác Ács
- Faculty of Health Sciences, University of Pécs, 7621 Pécs, Hungary
| | | | - Blanka Tóth
- Department of Pulmonary Rehabilitation, National Koranyi Institute of Pulmonology, 1122 Budapest, Hungary
| | - Mária Kerti
- Department of Pulmonary Rehabilitation, National Koranyi Institute of Pulmonology, 1122 Budapest, Hungary
| | - Antal Kovács
- Faculty of Health Sciences, University of Pécs, 7621 Pécs, Hungary
| | - János Tamás Varga
- Department of Pulmonology, Semmelweis University, 1083 Budapest, Hungary
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Fekete M, Szollosi G, Tarantini S, Lehoczki A, Nemeth AN, Bodola C, Varga L, Varga JT. Metabolic syndrome in patients with COPD: Causes and pathophysiological consequences. Physiol Int 2022; 109:90-105. [PMID: 35238797 DOI: 10.1556/2060.2022.00164] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 02/12/2022] [Accepted: 02/15/2022] [Indexed: 11/19/2022]
Abstract
BACKGROUND Decreased physical activity significantly increases the probability of prevalent metabolic syndrome (MetS) with substantial impact on the expected course of COPD. OBJECTIVE Our research aims to assess the metabolic consequences of chronic obstructive pulmonary disease (COPD) and evaluate the prevalence of MetS and its interrelations with age, sex, comorbidities, drug intake, degree of decreased lung function, nutritional status, physical activity and quality of life. METHODS A cross-sectional study was performed on a random sample (n = 401) at the Department of Pulmonary Rehabilitation of the National Koranyi Institute of Pulmonology from March 1, 2019 to March 1, 2020 in Budapest, Hungary. Anthropometric and respiratory function tests and laboratory parameters of all patients were registered. RESULTS MetS occurred in 59.1% of COPD patients with significant gender difference (male: 49.7% female: 67.6%). Concerning BMI, the prevalence of MetS was higher with BMI≥25 kg m-2 (P < 0.0001). Patients with this syndrome had significantly worse FEV1%pred (43 (30-56) vs. 47 (36-61); P = 0.028), lower quality of life (CAT: 26 (21-32) vs. 24.5 (19-29); P = 0.049) and significantly more frequent exacerbations (2 (1-3) vs.1 (0-2); P < 0.05), than patients without MetS. The prevalence of comorbidities were higher in overweight/obese patients (BMI> 25 kg m-2). CONCLUSIONS In COPD patients MetS negatively affect respiratory function and quality of life and promotes exacerbations of the disease. MetS is related to nutritional status and the level of systemic inflammation in COPD patients.
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Affiliation(s)
- Monika Fekete
- 1 Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gergo Szollosi
- 2 Department of Family and Occupational Medicine, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
| | - Stefano Tarantini
- 3 Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73132, USA
| | - Andrea Lehoczki
- 4 National Institute for Haematology and Infectious Diseases, Department of Haematology and Stem Cell Transplantation, South Pest Central Hospital, Budapest, Hungary
| | - Anna N Nemeth
- 1 Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Csenge Bodola
- 1 Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Luca Varga
- 1 Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Janos Tamas Varga
- 5 Department of Pulmonology, Semmelweis University, Budapest, Hungary
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8
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Fekete M, Szarvas Z, Fazekas-Pongor V, Feher A, Dosa N, Lehoczki A, Tarantini S, Varga JT. COVID-19 infection in patients with chronic obstructive pulmonary disease: From pathophysiology to therapy. Mini-review. Physiol Int 2022; 109:9-19. [PMID: 35230261 DOI: 10.1556/2060.2022.00172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/06/2022] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Patients with chronic obstructive pulmonary disease (COPD) are a vulnerable group in terms of the outcome of coronavirus infection in relation to their disease or its treatment, with a higher risk of developing serious complications compared to the healthy population. AIM The aim of our summary study is to review the background and health outcomes of chronic obstructive pulmonary disease and COVID-19 infection in the presence of both diseases. METHODS Review of national and international medical databases (PubMed, MEDLINE, and MOB) with keywords COPD, COVID-19, disease risk, cause, prevention, complications, and prognosis. RESULTS Meta-analyses show that COPD is one of the most common underlying conditions in patients hospitalized for COVID-19. Such patients are five times more likely to develop a serious complication due to oxygen supply problems therefore they are more likely to be admitted to intensive care units, where they may require mechanical ventilation. In the case of underlying COPD, the usual care plan for COVID-19 infection should be followed, as well as all public health recommendations to minimize the risk of developing and transmitting COVID-19. CONCLUSION Coronavirus infection is especially dangerous for COPD patients, who are much more likely to become seriously ill, so increased surveillance, prevention, early detection, adequate treatment and rehabilitation of the disease group are of paramount importance.
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Affiliation(s)
- Monika Fekete
- 1 Department of Public Health, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Zsofia Szarvas
- 1 Department of Public Health, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Vince Fazekas-Pongor
- 1 Department of Public Health, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Agnes Feher
- 1 Department of Public Health, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Norbert Dosa
- 1 Department of Public Health, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Andrea Lehoczki
- 2 Department of Hematology and Stem Cell Transplantation, National Institute for Hematology and Infectious Diseases, South Pest Central Hospital, Budapest, Hungary
| | - Stefano Tarantini
- 1 Department of Public Health, Semmelweis University, Faculty of Medicine, Budapest, Hungary
- 3 Department of Biochemistry and Molecular Biology at University of Oklahoma Health Sciences Center, Oklahoma City, OK,USA
| | - Janos Tamas Varga
- 4 Department of Pulmonology, Semmelweis University, Budapest, Hungary
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Role of new digital technologies and telemedicine in pulmonary rehabilitation : Smart devices in the treatment of chronic respiratory diseases. Wien Klin Wochenschr 2021; 133:1201-1207. [PMID: 34460006 PMCID: PMC8599213 DOI: 10.1007/s00508-021-01930-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 07/23/2021] [Indexed: 10/28/2022]
Abstract
BACKGROUND Asthma and chronic obstructive pulmonary diseases are conditions characterized by a variable progression. Some individuals experience longer asymptomatic periods while others acute worsening periods and/or exacerbations triggered by symptom multiplication factors. Medications are adjusted to the patients' respiratory function, self-assessment of health and emerging certain physical changes. A more effective treatment may be applied by real-time data registered during the patient's everyday life. AIM AND METHODS Introducing new modern digital technology in pulmonary rehabilitation (PR) to help tracking the patients' medication, thus we systematically reviewed the latest publications on telemedicine and pulmonary telerehabilitation. CONCLUSION The use of the latest digital technologies in PR is very exciting and offers great opportunities while treating patients affected by specific conditions. On the one hand, adherence to medication can be improved in patients with chronic respiratory diseases by using these new state of the art devices; on the other hand, digital devices will also be able to monitor various physiological parameters of patients during their usual everyday activities. Data can be stored on a smartphone and shared with the provider. Relying on this information, physicians will be able to tailor medications and dosage to the specific needs of individual patients. Telerehabilitation may be a sustainable solution to the growing burden of chronic respiratory disease worldwide. However, PR must keep its cornerstones, such as education and motivations, which are most successful when conducted in person. Many issues remain to be resolved in the future, e.g. cybersecurity while using smart devices since they offer unique opportunities for PR.
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Area under flow-volume loop may predict severe exacerbation in COPD patients with high grade of dyspnea. Respir Physiol Neurobiol 2021; 294:103771. [PMID: 34358727 DOI: 10.1016/j.resp.2021.103771] [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: 03/26/2021] [Revised: 06/27/2021] [Accepted: 08/02/2021] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Exacerbations in patients with COPD may still be unpredictable, although the general risk factors have been well defined. We aimed to determine the role of a novel parameter, area under flow-volume loop, in predicting severe exacerbations. METHODS In this single-centre retrospective cohort study, 81 COPD patients over 40 years of age with high grade of dyspnea (having a CAT score of ≥10) and a history of ≥1 moderate exacerbation in the previous year were included. Area under flow-volume curve (AreaFE%) was obtained from pulmonary function test graph and calculated from Matlab programme. Univariate and multivariate logistic regression analyses were performed to determine independent risk factors of the severe exacerbation. RESULTS Patients with severe exacerbation (n = 70, 86.4 %) were older. They had lower FEV1%, FVC%, 6MWD, AreaFE% and higher CAT score than patients without exacerbation. After performing multivariate analysis, high CAT score and low AreaFE% value were found to be independent risk factors for severe exacerbation (OR: 1.12, 95 % CI: 1.065-1.724; p = 0.01 and OR: 1.18, 95 % CI: 0.732-0.974; p = 0.02). CONCLUSIONS We found that a low AreaFE% value was an independent risk factor in addition to a high CAT score and these both have an excellent discriminative ability in predicting the risk of severe exacerbation.
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Tiller NB, Cao M, Lin F, Yuan W, Wang CY, Abbasi A, Calmelat R, Soriano A, Rossiter HB, Casaburi R, Stringer WW, Porszasz J. Dynamic airway function during exercise in COPD assessed via impulse oscillometry before and after inhaled bronchodilators. J Appl Physiol (1985) 2021; 131:326-338. [PMID: 34013748 PMCID: PMC8325613 DOI: 10.1152/japplphysiol.00148.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Assessing airway function during exercise provides useful information regarding mechanical properties of the airways and the extent of ventilatory limitation in COPD. The primary aim of this study was to use impulse oscillometry (IOS) to assess dynamic changes in airway impedance across a range of exercise intensities in patients with GOLD 1-4, before and after albuterol administration. A secondary aim was to assess the reproducibility of IOS measures during exercise. Fifteen patients with COPD (8 males/7 females; age = 66 ± 8 yr; prebronchodilator FEV1 = 54.3 ± 23.6%Pred) performed incremental cycle ergometry before and 90 min after inhaled albuterol. Pulmonary ventilation and gas exchange were measured continuously, and IOS-derived indices of airway impedance were measured every 2 min immediately preceding inspiratory capacity maneuvers. Test-retest reproducibility of exercise IOS was assessed as mean difference between replicate tests in five healthy subjects (3 males/2 females). At rest and during incremental exercise, albuterol significantly increased airway reactance (X5) and decreased airway resistance (R5, R5-R20), impedance (Z5), and end-expiratory lung volume (60% ± 12% vs. 58% ± 12% TLC, main effect P = 0.003). At peak exercise, there were moderate-to-strong associations between IOS variables and IC, and between IOS variables and concavity in the expiratory limb of the spontaneous flow-volume curve. Exercise IOS exhibited moderate reproducibility in healthy subjects which was strongest with R5 (mean diff. = -0.01 ± 0.05 kPa/L/s; ICC = 0.68), R5-R20 (mean diff. = -0.004 ± 0.028 kPa/L/s; ICC = 0.65), and Z5 (mean diff. = -0.006 ± 0.021 kPa/L/s; ICC = 0.69). In patients with COPD, exercise evoked increases in airway resistance and decreases in reactance that were ameliorated by inhaled bronchodilators. The technique of exercise IOS may aid in the clinical assessment of dynamic airway function during exercise.NEW & NOTEWORTHY This study provides a novel, mechanistic insight into dynamic airway function during exercise in COPD, before and after inhaled bronchodilators. The use of impulse oscillometry (IOS) to evaluate airway function is unique among exercise studies. We show strong correlations among IOS variables, dynamic hyperinflation, and shape-changes in the spontaneous expiratory flow-volume curve. This approach may aid in the clinical assessment of airway function during exercise.
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Affiliation(s)
- Nicholas B. Tiller
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Min Cao
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California,2Department of Respiratory and Critical Care Medicine, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Fang Lin
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California,3Department of Respiratory, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Wei Yuan
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California,3Department of Respiratory, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Chu-Yi Wang
- 4Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, California
| | - Asghar Abbasi
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Robert Calmelat
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - April Soriano
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Harry B. Rossiter
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Richard Casaburi
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - William W. Stringer
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Janos Porszasz
- 1Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
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Fekete M, Fazekas-Pongor V, Balazs P, Tarantini S, Szollosi G, Pako J, Nemeth AN, Varga JT. Effect of malnutrition and body composition on the quality of life of COPD patients. Physiol Int 2021; 108:238-250. [PMID: 34224400 DOI: 10.1556/2060.2021.00170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 01/18/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Pathological alterations in nutritional status may develop in Chronic Obstructive Pulmonary Disease (COPD) patients through production of inflammatory cytokines and inadequate diet. OBJECTIVE The aim of our study was to determine the correlation between nutritional status and quality of life of COPD patients. METHODS We evaluated the nutritional status of COPD patients of Hungarian National Koranyi Institute for Pulmonology using the Malnutrition Universal Screening Tool (MUST) and bioelectrical impedance analysis (BIA) between January 1 and June 1, 2019. Lung function, physical fitness, and respiratory muscle strength were included in the assessment. RESULTS Fifty patients (mean age was 66.3 ± 9.6 years) participated in our study. Mean body mass index (BMI) was 26.2 ± 6.1 kg/m2 and mean fat-free mass index (FFMI) was 16.8 ± 2.4 kg/m2. Overweight patients had better lung function values (FEV1ref%: 46.3 ± 15.2) than normal (FEV1ref%: 45.1 ± 20.9) and underweight patients (FEV1ref%: 43.8 ± 16.0). The Modified Medical Research Council Dyspnea Scale (mMRC) was significantly associated with various parameters; strongest correlation was found with FFMI (r = -0.537, P < 0.001), skeletal muscle mass index (SMMI) (r = -0.530, P < 0.001), and 6-minute walking distance (6MWD) (r = -0.481, P < 0.001). CONCLUSIONS Our results indicate that malnourished COPD patients may have reduced lung function and lower quality of life compared to normal weight patients. Thus, our findings suggest that nutritional therapy be included in the treatment of COPD patients combined with nutritional risk screening and BIA during the follow-up.
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Affiliation(s)
- M Fekete
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - V Fazekas-Pongor
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - P Balazs
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - S Tarantini
- 2Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- 3Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - G Szollosi
- 4Department of Family and Occupational Medicine, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
| | - J Pako
- 6National Korányi Institute for Pulmonology, Budapest, Hungary
| | - A N Nemeth
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - J T Varga
- 5Department of Pulmonology, Semmelweis University, Budapest, Hungary
- 6National Korányi Institute for Pulmonology, Budapest, Hungary
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Giri PC, Chowdhury AM, Bedoya A, Chen H, Lee HS, Lee P, Henriquez C, MacIntyre NR, Huang YCT. Application of Machine Learning in Pulmonary Function Assessment Where Are We Now and Where Are We Going? Front Physiol 2021; 12:678540. [PMID: 34248665 PMCID: PMC8264499 DOI: 10.3389/fphys.2021.678540] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/02/2021] [Indexed: 12/24/2022] Open
Abstract
Analysis of pulmonary function tests (PFTs) is an area where machine learning (ML) may benefit clinicians, researchers, and the patients. PFT measures spirometry, lung volumes, and carbon monoxide diffusion capacity of the lung (DLCO). The results are usually interpreted by the clinicians using discrete numeric data according to published guidelines. PFT interpretations by clinicians, however, are known to have inter-rater variability and the inaccuracy can impact patient care. This variability may be caused by unfamiliarity of the guidelines, lack of training, inadequate understanding of lung physiology, or simply mental lapses. A rules-based automated interpretation system can recapitulate expert’s pattern recognition capability and decrease errors. ML can also be used to analyze continuous data or the graphics, including the flow-volume loop, the DLCO and the nitrogen washout curves. These analyses can discover novel physiological biomarkers. In the era of wearables and telehealth, particularly with the COVID-19 pandemic restricting PFTs to be done in the clinical laboratories, ML can also be used to combine mobile spirometry results with an individual’s clinical profile to deliver precision medicine. There are, however, hurdles in the development and commercialization of the ML-assisted PFT interpretation programs, including the need for high quality representative data, the existence of different formats for data acquisition and sharing in PFT software by different vendors, and the need for collaboration amongst clinicians, biomedical engineers, and information technologists. Hurdles notwithstanding, the new developments would represent significant advances that could be the future of PFT, the oldest test still in use in clinical medicine.
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Affiliation(s)
- Paresh C Giri
- Division of Pulmonary and Critical Care Medicine, Loma Linda University Medical Center, Loma Linda, CA, United States
| | - Anand M Chowdhury
- Division of Pulmonary, Allergy and Critical Care Medicine, Duke University Medical Center, Durham, NC, United States
| | - Armando Bedoya
- Division of Pulmonary, Allergy and Critical Care Medicine, Duke University Medical Center, Durham, NC, United States
| | - Hengji Chen
- Department of Mechanical Engineering and Materials Science, Pratt School of Engineering, Duke University Medical Center, Durham, NC, United States
| | - Hyun Suk Lee
- Hartford HealthCare, Hartford, CT, United States
| | - Patty Lee
- Division of Pulmonary, Allergy and Critical Care Medicine, Duke University Medical Center, Durham, NC, United States
| | - Craig Henriquez
- Department of Mechanical Engineering and Materials Science, Pratt School of Engineering, Duke University Medical Center, Durham, NC, United States
| | - Neil R MacIntyre
- Division of Pulmonary, Allergy and Critical Care Medicine, Duke University Medical Center, Durham, NC, United States
| | - Yuh-Chin T Huang
- Division of Pulmonary, Allergy and Critical Care Medicine, Duke University Medical Center, Durham, NC, United States
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14
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Fazekas-Pongor V, Fekete M, Balazs P, Árva D, Pénzes M, Tarantini S, Urbán R, Varga JT. Health-related quality of life of COPD patients aged over 40 years. Physiol Int 2021; 108:261-273. [PMID: 34166221 DOI: 10.1556/2060.2021.00017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/27/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Chronic obstructive pulmonary disease (COPD) is the fourth most frequent disease globally, and its worldwide prevalence is projected to increase in the following decades. Health-related quality of life (HRQOL) of COPD patients depends on multiple factors. OBJECTIVE The aim of this study was to identify the most important risk factors affecting HRQOL of COPD patients and to measure how specific clinical parameters can predict HRQOL. METHODS A questionnaire-based cross-sectional study combined with clinical data was conducted among patients diagnosed with COPD (n = 321, 52.6% females, mean age 66.4 ± 9.5) at the National Koranyi Institute for Pulmonology, Budapest in 2019-2020. The inclusion criteria were age ≥40 years and existing COPD. Multivariate linear regression analyses were conducted on three components of the COPD-specific Saint George's Respiratory Questionnaire (SGRQ-C) and on the physical (PCS) and mental component scales (MCS) of the 36-Item Short Form Health Survey (SF-36). Multiple linear regression analysis was performed to evaluate the effects of patient and disease characteristics on COPD Assessment Test (CAT) scores. RESULTS We found that frequent exacerbations, multiple comorbidities and tobacco smoking were associated with worse HRQOL. Engaging in more frequent physical activity and better 6-minute walking distance results were associated with better HRQOL. CONCLUSIONS Our results indicate that the complex therapy of COPD should focus not only on improving lung functions and preventing exacerbation, but also on treating comorbidities, encouraging increased physical activity, and supporting smoking cessation to assure better HRQOL for patients.
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Affiliation(s)
- V Fazekas-Pongor
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest H-1085, Hungary
| | - M Fekete
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest H-1085, Hungary
| | - P Balazs
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest H-1085, Hungary
| | - D Árva
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest H-1085, Hungary
| | - M Pénzes
- 1Department of Public Health, Faculty of Medicine, Semmelweis University, Budapest H-1085, Hungary
| | - S Tarantini
- 2University of Oklahoma Health Sciences Center, Department of Biochemistry and Molecular Biology, Oklahoma City, OK 73132, USA
- 3Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - R Urbán
- 4Institute of Psychology, Eötvös Loránd University, Budapest H-1064, Hungary
| | - J T Varga
- 5Department of Pulmonology, Semmelweis University, Budapest, Hungary
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15
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Erram J, Bari M, Domingo A, Cannon DT. Pulmonary function with expiratory resistive loading in healthy volunteers. PLoS One 2021; 16:e0252916. [PMID: 34115812 PMCID: PMC8195373 DOI: 10.1371/journal.pone.0252916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 05/25/2021] [Indexed: 11/19/2022] Open
Abstract
Expiratory flow limitation is a key characteristic in obstructive pulmonary diseases. To study abnormal lung mechanics isolated from heterogeneities of obstructive disease, we measured pulmonary function in healthy adults with expiratory loading. Thirty-seven volunteers (25±5 yr) completed spirometry and body plethysmography under control and threshold expiratory loading of 7, 11 cmH2O, and a subset at 20 cmH2O (n = 11). We analyzed the shape of the flow-volume relationship with rectangular area ratio (RAR; Ma et al., Respir Med 2010). Airway resistance was increased (p<0.0001) with 7 and 11 cmH2O loading vs control (9.20±1.02 and 11.76±1.68 vs. 2.53± 0.80 cmH2O/L/s). RAR was reduced (p = 0.0319) in loading vs control (0.45±0.07 and 0.47±0.09L vs. 0.48±0.08). FEV1 was reduced (p<0.0001) in loading vs control (3.24±0.81 and 3.23±0.80 vs. 4.04±1.05 L). FVC was reduced (p<0.0001) in loading vs control (4.11±1.01 and 4.14±1.03 vs. 5.03±1.34 L). Peak expiratory flow (PEF) was reduced (p<0.0001) in loading vs control (6.03±1.67 and 6.02±1.84 vs. 8.50±2.81 L/s). FEV1/FVC (p<0.0068) was not clinically significant and FRC (p = 0.4) was not different in loading vs control. Supra-physiologic loading at 20 cmH2O did not result in further limitation. Expiratory loading reduced FEV1, FVC, PEF, but there were no clinically meaningful differences in FEV1/FVC, FRC, or RAR. Imposed expiratory loading likely leads to high airway pressures that resist dynamic airway compression. Thus, a concave expiratory flow-volume relationship was consistently absent-a key limitation for model comparison with pulmonary function in COPD. Threshold loading may be a useful strategy to increase work of breathing or induce dynamic hyperinflation.
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Affiliation(s)
- Jyotika Erram
- School of Exercise & Nutritional Sciences, San Diego State University, San Diego, California, United States of America
| | - Monica Bari
- School of Exercise & Nutritional Sciences, San Diego State University, San Diego, California, United States of America
| | - Antoinette Domingo
- School of Exercise & Nutritional Sciences, San Diego State University, San Diego, California, United States of America
| | - Daniel T. Cannon
- School of Exercise & Nutritional Sciences, San Diego State University, San Diego, California, United States of America
- * E-mail:
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16
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Stringer WW, Porszasz J, Cao M, Rossiter HB, Siddiqui S, Rennard S, Casaburi R. The effect of long-acting dual bronchodilator therapy on exercise tolerance, dynamic hyperinflation, and dead space during constant work rate exercise in COPD. J Appl Physiol (1985) 2021; 130:2009-2018. [PMID: 33914661 PMCID: PMC8526332 DOI: 10.1152/japplphysiol.00774.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated whether dual bronchodilator therapy (glycopyrrolate/formoterol fumarate; GFF; Bevespi Aerosphere) would increase exercise tolerance during a high-intensity constant work rate exercise test (CWRET) and the relative contributions of dead space ventilation (VD/VT) and dynamic hyperinflation (change in inspiratory capacity) to exercise limitation in chronic obstructive pulmonary disease (COPD). In all, 48 patients with COPD (62.9 ± 7.6 yrs; 33 male; GOLD spirometry stage 1/2/3/4, n = 2/35/11/0) performed a randomized, double blind, placebo (PL) controlled, two-period crossover, single-center trial. Gas exchange and inspiratory capacity (IC) were assessed during cycle ergometry at 80% incremental exercise peak work rate. Transcutaneous [Formula: see text] (Tc[Formula: see text]) measurement was used for VD/VT estimation. Baseline postalbuterol forced expiratory volume in 1 s (FEV1) was 1.86 ± 0.58 L (63.6% ± 13.9 predicted). GFF increased FEV1 by 0.18 ± 0.21 L relative to placebo (PL; P < 0.001). CWRET endurance time was greater after GFF vs. PL (383 ± 184 s vs. 328 ± 115 s; difference 55 ± 125 s; P = 0.013; confidence interval: 20-90 s), a 17% increase. IC on GFF was above placebo IC at all time points and fell less with GFF vs. PL (P ≤ 0.0001). Isotime tidal volume (1.54 ± 0.50 vs. 1.47 ± 0.45 L; P = 0.022) and ventilation (52.9 ± 19.9 vs. 51.0 ± 18.9 L/min; P = 0.011) were greater, and respiratory rate was unchanged (34.9 ± 9.2 vs. 35.1 ± 8.0 br/min, P = 0.865). Isotime VD/VT did not differ between groups (GFF 0.28 ± 0.08 vs. PL 0.27 ± 0.09; P = 0.926). GFF increased exercise tolerance in patients with COPD, and the increase was accompanied by attenuated dynamic hyperinflation without altering VD/VT.NEW & NOTEWORTHY This study was a randomized clinical trial (NCT03081156) that collected detailed physiology data to investigate the effect of dual bronchodilator therapy on exercise tolerance in COPD, and additionally to determine the relative contributions of changes in dead space ventilation (VD/VT) and dynamic hyperinflation to alterations in exercise limitation. We utilized a unique noninvasive method to assess VD/VT (transcutaneous carbon dioxide, Tc[Formula: see text]) and found that dual bronchodilators yielded a moderate improvement in exercise tolerance. Importantly, attenuation of dynamic hyperinflation rather than change in dead space ventilation was the most important contributor to exercise tolerance improvement.
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Affiliation(s)
- William W Stringer
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Janos Porszasz
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Min Cao
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
| | - Harry B Rossiter
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California.,Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Stephen Rennard
- BioPharmaceuticals R&D, AstraZeneca, Cambridge, United Kingdom.,Department of Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Richard Casaburi
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
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17
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Neder JA, Phillips DB, Marillier M, Bernard AC, Berton DC, O'Donnell DE. Clinical Interpretation of Cardiopulmonary Exercise Testing: Current Pitfalls and Limitations. Front Physiol 2021; 12:552000. [PMID: 33815128 PMCID: PMC8012894 DOI: 10.3389/fphys.2021.552000] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 03/01/2021] [Indexed: 12/12/2022] Open
Abstract
Several shortcomings on cardiopulmonary exercise testing (CPET) interpretation have shed a negative light on the test as a clinically useful tool. For instance, the reader should recognize patterns of dysfunction based on clusters of variables rather than relying on rigid interpretative algorithms. Correct display of key graphical data is of foremost relevance: prolixity and redundancy should be avoided. Submaximal dyspnea ratings should be plotted as a function of work rate (WR) and ventilatory demand. Increased work of breathing and/or obesity may normalize peak oxygen uptake (V̇O2) despite a low peak WR. Among the determinants of V̇O2, only heart rate is measured during non-invasive CPET. It follows that in the absence of findings suggestive of severe impairment in O2 delivery, the boundaries between inactivity and early cardiovascular disease are blurred in individual subjects. A preserved breathing reserve should not be viewed as evidence that "the lungs" are not limiting the subject. In this context, measurements of dynamic inspiratory capacity are key to uncover abnormalities germane to exertional dyspnea. A low end-tidal partial pressure for carbon dioxide may indicate either increased "wasted" ventilation or alveolar hyperventilation; thus, direct measurements of arterial (or arterialized) PO2 might be warranted. Differentiating a chaotic breathing pattern from the normal breath-by-breath noise might be complex if the plotted data are not adequately smoothed. A sober recognition of these limitations, associated with an interpretation report free from technicalities and convoluted terminology, is crucial to enhance the credibility of CPET in the eyes of the practicing physician.
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Affiliation(s)
- J Alberto Neder
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Devin B Phillips
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Mathieu Marillier
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Anne-Catherine Bernard
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Danilo C Berton
- Division of Respirology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Denis E O'Donnell
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
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18
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Strozza D, Wilhite DP, Babb TG, Bhammar DM. Pitfalls in Expiratory Flow Limitation Assessment at Peak Exercise in Children: Role of Thoracic Gas Compression. Med Sci Sports Exerc 2020; 52:2310-2319. [PMID: 33064406 PMCID: PMC7573195 DOI: 10.1249/mss.0000000000002378] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Thoracic gas compression and exercise-induced bronchodilation can influence the assessment of expiratory flow limitation (EFL) during cardiopulmonary exercise tests. The purpose of this study was to examine the effect of thoracic gas compression and exercise-induced bronchodilation on the assessment of EFL in children with and without obesity. METHODS Forty children (10.7 ± 1.0 yr; 27 obese; 15 with EFL) completed pulmonary function tests and incremental exercise tests. Inspiratory capacity maneuvers were performed during the incremental exercise test for the placement of tidal flow volume loops within the maximal expiratory flow volume (MEFV) loops, and EFL was calculated as the overlap between the tidal and the MEFV loops. MEFV loops were plotted with volume measured at the lung using plethysmography (MEFVp), with volume measured at the mouth using spirometry concurrent with measurements in the plethysmograph (MEFVm), and from spirometry before (MEFVpre) and after (MEFVpost) the incremental exercise test. Only the MEFVp loops were corrected for thoracic gas compression. RESULTS Not correcting for thoracic gas compression resulted in incorrect diagnosis of EFL in 23% of children at peak exercise. EFL was 26% ± 15% VT higher for MEFVm compared with MEFVp (P < 0.001), with no differences between children with and without obesity (P = 0.833). The difference in EFL estimation using MEFVpre (37% ± 30% VT) and MEFVpost (31% ± 26% VT) did not reach statistical significance (P = 0.346). CONCLUSIONS Not correcting the MEFV loops for thoracic gas compression leads to the overdiagnosis and overestimation of EFL. Because most commercially available metabolic measurement systems do not correct for thoracic gas compression during spirometry, there may be a significant overdiagnosis of EFL in cardiopulmonary exercise testing. Therefore, clinicians must exercise caution while interpreting EFL when the MEFV loop is derived through spirometry.
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Affiliation(s)
- Danielle Strozza
- School of Medicine, University of Nevada Las Vegas, Las Vegas, NV
| | - Daniel P. Wilhite
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX
| | - Tony G. Babb
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX
| | - Dharini M. Bhammar
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and UT Southwestern Medical Center, Dallas, TX
- Department of Kinesiology and Nutrition Sciences, School of Integrated Health Sciences, University of Nevada Las Vegas, Las Vegas, NV
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19
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Milne KM, Domnik NJ, Phillips DB, James MD, Vincent SG, Neder JA, O'Donnell DE. Evaluation of Dynamic Respiratory Mechanical Abnormalities During Conventional CPET. Front Med (Lausanne) 2020; 7:548. [PMID: 33072774 PMCID: PMC7533639 DOI: 10.3389/fmed.2020.00548] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/31/2020] [Indexed: 12/21/2022] Open
Abstract
Assessment of the ventilatory response to exercise is important in evaluating mechanisms of dyspnea and exercise intolerance in chronic cardiopulmonary diseases. The characteristic mechanical derangements that occur during exercise in chronic respiratory conditions have previously been determined in seminal studies using esophageal catheter pressure-derived measurements. In this brief review, we examine the emerging role and clinical utility of conventional assessment of dynamic respiratory mechanics during exercise testing. Thus, we provide a physiologic rationale for measuring operating lung volumes, breathing pattern, and flow-volume loops during exercise. We consider standardization of inspiratory capacity-derived measurements and their practical implementation in clinical laboratories. We examine the evidence that this iterative approach allows greater refinement in evaluation of ventilatory limitation during exercise than traditional assessments of breathing reserve. We appraise the available data on the reproducibility and responsiveness of this methodology. In particular, we review inspiratory capacity measurement and derived operating lung volumes during exercise. We demonstrate, using recent published data, how systematic evaluation of dynamic mechanical constraints, together with breathing pattern analysis, can provide valuable insights into the nature and extent of physiological impairment contributing to exercise intolerance in individuals with common chronic obstructive and restrictive respiratory disorders.
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Affiliation(s)
- Kathryn M Milne
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada.,Clinician Investigator Program, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Nicolle J Domnik
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada
| | - Matthew D James
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada
| | - J Alberto Neder
- Laboratory of Clinical Exercise Physiology, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Kingston Health Sciences Centre & Queen's University, Kingston, ON, Canada
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20
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Bodduluri S, Nakhmani A, Reinhardt JM, Wilson CG, McDonald ML, Rudraraju R, Jaeger BC, Bhakta NR, Castaldi PJ, Sciurba FC, Zhang C, Bangalore PV, Bhatt SP. Deep neural network analyses of spirometry for structural phenotyping of chronic obstructive pulmonary disease. JCI Insight 2020; 5:132781. [PMID: 32554922 PMCID: PMC7406302 DOI: 10.1172/jci.insight.132781] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 06/03/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUNDCurrently recommended traditional spirometry outputs do not reflect the relative contributions of emphysema and airway disease to airflow obstruction. We hypothesized that machine-learning algorithms can be trained on spirometry data to identify these structural phenotypes.METHODSParticipants enrolled in a large multicenter study (COPDGene) were included. The data points from expiratory flow-volume curves were trained using a deep-learning model to predict structural phenotypes of chronic obstructive pulmonary disease (COPD) on CT, and results were compared with traditional spirometry metrics and an optimized random forest classifier. Area under the receiver operating characteristic curve (AUC) and weighted F-score were used to measure the discriminative accuracy of a fully convolutional neural network, random forest, and traditional spirometry metrics to phenotype CT as normal, emphysema-predominant (>5% emphysema), airway-predominant (Pi10 > median), and mixed phenotypes. Similar comparisons were made for the detection of functional small airway disease phenotype (>20% on parametric response mapping).RESULTSAmong 8980 individuals, the neural network was more accurate in discriminating predominant emphysema/airway phenotypes (AUC 0.80, 95%CI 0.79-0.81) compared with traditional measures of spirometry, FEV1/FVC (AUC 0.71, 95%CI 0.69-0.71), FEV1% predicted (AUC 0.70, 95%CI 0.68-0.71), and random forest classifier (AUC 0.78, 95%CI 0.77-0.79). The neural network was also more accurate in discriminating predominant emphysema/small airway phenotypes (AUC 0.91, 95%CI 0.90-0.92) compared with FEV1/FVC (AUC 0.80, 95%CI 0.78-0.82), FEV1% predicted (AUC 0.83, 95%CI 0.80-0.84), and with comparable accuracy with random forest classifier (AUC 0.90, 95%CI 0.88-0.91).CONCLUSIONSStructural phenotypes of COPD can be identified from spirometry using deep-learning and machine-learning approaches, demonstrating their potential to identify individuals for targeted therapies.TRIAL REGISTRATIONClinicalTrials.gov NCT00608764.FUNDINGThis study was supported by NIH grants K23 HL133438 and R21EB027891 and an American Thoracic Foundation 2018 Unrestricted Research Grant. The COPDGene study is supported by NIH grants NHLBI U01 HL089897 and U01 HL089856. The COPDGene study (NCT00608764) is also supported by the COPD Foundation through contributions made to an Industry Advisory Committee comprising AstraZeneca, Boehringer-Ingelheim, GlaxoSmithKline, Novartis, and Sunovion.
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Affiliation(s)
- Sandeep Bodduluri
- UAB Lung Imaging Core
- UAB Lung Health Center
- Division of Pulmonary, Allergy and Critical Care Medicine, and
| | - Arie Nakhmani
- Department of Electrical and Computer Engineering, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Joseph M. Reinhardt
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA
| | - Carla G. Wilson
- Department of Biostatistics and Bioinformatics, National Jewish Health, Denver, Colorado, USA
| | - Merry-Lynn McDonald
- UAB Lung Health Center
- Division of Pulmonary, Allergy and Critical Care Medicine, and
| | | | - Byron C. Jaeger
- Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Nirav R. Bhakta
- Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, University California, San Francisco, San Francisco, California, USA
| | - Peter J. Castaldi
- Channing Division of Network Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, USA
| | - Frank C. Sciurba
- Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Chengcui Zhang
- Department of Computer Science, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | - Surya P. Bhatt
- UAB Lung Imaging Core
- UAB Lung Health Center
- Division of Pulmonary, Allergy and Critical Care Medicine, and
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Satici C, Arpinar Yigitbas B, Demirkol MA, Kosar. Determining emphysema in adult patients with COPD-bronchiectasis overlap using a novel spirometric parameter: area under the forced expiratory flow-volume loop. Expert Rev Respir Med 2020; 14:839-844. [PMID: 32379507 DOI: 10.1080/17476348.2020.1766972] [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: 10/24/2022]
Abstract
BACKGROUND Defining the optimal therapeutic approach in patients with chronic obstructive pulmonary disease (COPD) bronchiectasis overlap (CBO) is challenging. The presence of emphysema suggests that COPD is the primary problem and it impacts therapeutic decision making. RESEARCH DESIGN AND METHODS We hypothesized that the AreaFE% performance will be reliable in diagnosing the presence of emphysema such that serial CT scanning may not be needed. In this retrospective chart review study, we included 113 CBO patients (52 having emphysema, 61 not having emphysema). We compared these two groups according to conventional spirometric parameters and AreaFE% values. RESULTS 54% of all patients were female and mean age was 58 years.FEV1%, FEV1/FVC and AreaFE% were found to be significantly lower in patients with emphysema. 12% is the cutoff value for AreaFE% in determining emphysema with 73% sensitivity,75% specificity, and 72% diagnostic accuracy (AUC: 0.82) and it provides superior estimation than conventional parameters. CONCLUSIONS We found that AreaFE% is more suitable for determining the presence of emphysema than conventional spirometric parameters in CBO patients. This novel parameter may be helpful instead of scanning thorax CT to indicate the presence of emphysema and manage treatment in the follow-up of CBO patients.
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Affiliation(s)
- Celal Satici
- Chest Disease Department, Gaziosmanpasa Research and Training Hospital , Istanbul, Turkey
| | - Burcu Arpinar Yigitbas
- Chest Disease Department, Yedikule Research and Training Hospital for Chest Diseases and Chest Surgery , Istanbul, Turkey
| | - Mustafa Asim Demirkol
- Chest Disease Department, Gaziosmanpasa Research and Training Hospital , Istanbul, Turkey
| | - Kosar
- Chest Disease Department, Yedikule Research and Training Hospital for Chest Diseases and Chest Surgery , Istanbul, Turkey
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Das N, Topalovic M, Aerts JM, Janssens W. Area under the forced expiratory flow-volume loop in spirometry indicates severe hyperinflation in COPD patients. Int J Chron Obstruct Pulmon Dis 2019; 14:409-418. [PMID: 30863041 PMCID: PMC6388784 DOI: 10.2147/copd.s185931] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background Severe hyperinflation causes detrimental effects such as dyspnea and reduced exercise capacity and is an independent predictor of mortality in COPD patients. Static lung volumes are required to diagnose severe hyperinflation, which are not always accessible in primary care. Several studies have shown that the area under the forced expiratory flow-volume loop (AreaFE) is highly sensitive to bronchodilator response and is correlated with residual volume/total lung capacity (RV/TLC), a common index of air trapping. In this study, we investigate the role of AreaFE% (AreaFE expressed as a percentage of reference value) and conventional spirometry parameters in indicating severe hyperinflation. Materials and methods We used a cohort of 215 individuals with COPD. The presence of severe hyperinflation was defined as elevated air trapping (RV/TLC >60%) or reduced inspiratory fraction (inspiratory capacity [IC]/TLC <25%) measured using body plethysmography. AreaFE% was calculated by integrating the maximal expiratory flow-volume loop with the trapezoidal rule and expressing it as a percentage of the reference value estimated using predicted values of FVC, peak expiratory flow and forced expiratory flow at 25%, 50% and 75% of FVC. Receiver operating characteristics (ROC) curve analysis was used to identify cut-offs that were used to indicate severe hyperinflation, which were then validated in a separate group of 104 COPD subjects. Results ROC analysis identified cut-offs of 15% and 20% for AreaFE% in indicating RV/TLC >60% and IC/TLC <25%, respectively (N=215). On validation (N=104), these cut-offs consistently registered the highest accuracy (80% each), sensitivity (68% and 75%) and specificity (83% and 80%) among conventional parameters in both criteria of severe hyperinflation. Conclusion AreaFE% consistently provides a superior estimation of severe hyperinflation using different indices, and may provide a convenient way to refer COPD patients for body plethysmography to address static lung volumes.
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Affiliation(s)
- Nilakash Das
- Laboratory of Respiratory Diseases, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, Leuven, Belgium,
| | - Marko Topalovic
- Laboratory of Respiratory Diseases, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, Leuven, Belgium,
| | - Jean-Marie Aerts
- Division of Animal and Human Health Engineering, Department of Biosystems, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Wim Janssens
- Laboratory of Respiratory Diseases, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, Leuven, Belgium,
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Stringer W, Marciniuk D. The Role of Cardiopulmonary Exercise Testing (CPET) in Pulmonary Rehabilitation (PR) of Chronic Obstructive Pulmonary Disease (COPD) Patients. COPD 2018; 15:621-631. [PMID: 30595047 DOI: 10.1080/15412555.2018.1550476] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Chronic obstructive pulmonary disease (COPD) is a common multisystem inflammatory disease with ramifications involving essentially all organ systems. Pulmonary rehabilitation is a comprehensive program designed to prevent and mitigate these disparate systemic effects and improve patient quality of life, functional status, and social functioning. Although initial patient assessment is a prominent component of any pulmonary rehabilitation (PR) program, cardiopulmonary exercise testing (CPET) is not regularly performed as a screening physiologic test prior to PR in COPD patients. Further, CPET is not often used to assess or document the improvement in exercise capacity related to completion of PR. In this review we will describe the classic physiologic abnormalities related to COPD on CPET parameters, the role of CPET in Risk Stratification/Safety prior to PR, the physiologic changes that occur in CPET parameters with PR, and the literature regarding the use of CPET to assess PR results. Finally, we will compare CPET to 6MW in COPD PR, the common minimal clinically important difference (MCID) is associated with CPET, and the potential future roles of CPET in PR and Research.
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Affiliation(s)
- William Stringer
- a Chronic Diseases Clinical Research Center (CDCRC), Los Angeles Biomedical Institute at Harbor-UCLA Medical Center , David Geffen School of Medicine at UCLA , Torrance , CA , USA
| | - Darcy Marciniuk
- b Respiratory Research Center, Royal University Hospital , University of Saskatchewan , Saskatoon , Canada
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New Spirometry Indices for Detecting Mild Airflow Obstruction. Sci Rep 2018; 8:17484. [PMID: 30504791 PMCID: PMC6269456 DOI: 10.1038/s41598-018-35930-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 11/13/2018] [Indexed: 11/17/2022] Open
Abstract
The diagnosis of chronic obstructive pulmonary disease (COPD) relies on demonstration of airflow obstruction. Traditional spirometric indices miss a number of subjects with respiratory symptoms or structural lung disease on imaging. We hypothesized that utilizing all data points on the expiratory spirometry curves to assess their shape will improve detection of mild airflow obstruction and structural lung disease. We analyzed spirometry data of 8307 participants enrolled in the COPDGene study, and derived metrics of airflow obstruction based on the shape on the volume-time (Parameter D), and flow-volume curves (Transition Point and Transition Distance). We tested associations of these parameters with CT measures of lung disease, respiratory morbidity, and mortality using regression analyses. There were significant correlations between FEV1/FVC with Parameter D (r = −0.83; p < 0.001), Transition Point (r = 0.69; p < 0.001), and Transition Distance (r = 0.50; p < 0.001). All metrics had significant associations with emphysema, small airway disease, dyspnea, and respiratory-quality of life (p < 0.001). The highest quartile for Parameter D was independently associated with all-cause mortality (adjusted HR 3.22,95% CI 2.42–4.27; p < 0.001) but a substantial number of participants in the highest quartile were categorized as GOLD 0 and 1 by traditional criteria (1.8% and 33.7%). Parameter D identified an additional 9.5% of participants with mild or non-recognized disease as abnormal with greater burden of structural lung disease compared with controls. The data points on the flow-volume and volume-time curves can be used to derive indices of airflow obstruction that identify additional subjects with disease who are deemed to be normal by traditional criteria.
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Porszasz J, Carraro N, Cao R, Gore A, Ma S, Jiang T, Maltais F, Ferguson GT, O'Donnell DE, Shaikh A, Rossiter HB, Casaburi R. Effect of tiotropium on spontaneous expiratory flow-volume curves during exercise in GOLD 1-2 COPD. Respir Physiol Neurobiol 2018; 251:8-15. [PMID: 29438808 DOI: 10.1016/j.resp.2018.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/12/2018] [Accepted: 02/08/2018] [Indexed: 11/27/2022]
Abstract
This substudy of a large, randomized, controlled trial (NCT01072396) examined tiotropium (18 μg qd) effects on dynamic hyperinflation during constant work rate treadmill exercise. Areas-under-the-spontaneous expiratory flow-volume (SEFV)-curves were compared in 20 COPD patients and 16 age-matched untreated controls, using rectangular area ratio (RAR) between peak intrabreath and end-expiratory flow. Seven patients exhibited SEFV curve concavity with RAR ≤ 0.5 (RARlow) in ≥1 test without tiotropium; (mean ± SD FEV1: 1.60 ± 0.59 L; 63.4 ± 14.0%predicted). In RARlow patients, tiotropium increased end-exercise inspiratory capacity (IC, 2.10 ± 0.05 vs. 1.89 ± 0.05 L, tiotropium vs. placebo; p = 0.045) and RAR (0.57 ± 0.02 vs. 0.53 ± 0.02; p < 0.001). Patients without SEFV curve concavity with RAR > 0.5 (n = 13; RARhigh), had higher screening FEV1 (2.15 ± 0.47 L; 79.6 ± 10.1%predicted) versus RARlow patients and no difference in end-exercise IC and RAR between tiotropium and placebo (IC: 2.24 ± 0.03 vs. 2.17 ± 0.03 L; RAR: 0.63 ± 0.005 vs. 0.62 ± 0.005). RAR and%predicted IC at peak exercise were positively correlated in RARlow patients (R2 = 0.43, p = 0.0002). Tiotropium increased exercise RAR in GOLD 1-2 patients with SEFV curve concavity.
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Affiliation(s)
- Janos Porszasz
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
| | - Nicolò Carraro
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Robert Cao
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
| | - Ashwani Gore
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Shuyi Ma
- Center for Infectious Disease Research, Seattle, WA, USA.
| | - Thomas Jiang
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - François Maltais
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Canada.
| | - Gary T Ferguson
- Pulmonary Research Institute of Southeast Michigan, Farmington Hills, MI, USA.
| | - Denis E O'Donnell
- Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada.
| | - Asif Shaikh
- Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, CT, USA.
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA; Faculty of Biological Sciences, University of Leeds, Leeds, UK.
| | - Richard Casaburi
- Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
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