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Milne S, Jetmalani K, Chapman DG, Duncan JM, Farah CS, Thamrin C, King GG. Respiratory system reactance reflects communicating lung volume in chronic obstructive pulmonary disease. J Appl Physiol (1985) 2019; 126:1223-1231. [PMID: 30763164 DOI: 10.1152/japplphysiol.00503.2018] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Respiratory system reactance (Xrs) measured by the forced oscillation technique (FOT) is theoretically and experimentally related to lung volume. In chronic obstructive pulmonary disease (COPD), the absolute volume measured by body plethysmography includes a proportion that is inaccessible to pressure oscillations applied via the mouth, that is, a "noncommunicating" lung volume. We hypothesized that in COPD the presence of noncommunicating lung would disrupt the expected Xrs-volume relationship compared with plethysmographic functional residual capacity (FRCpleth). Instead, Xrs would relate to estimates of communicating volume, namely, expiratory reserve volume (ERV) and single-breath alveolar volume (VaSB). We examined FOT and lung function data from people with COPD (n = 51) and from healthy volunteers (n = 40). In healthy volunteers, we observed an expected inverse relationship between reactance at 5 Hz (X5) and FRCpleth. In contrast, there was no such relationship between X5 and FRCpleth in COPD subjects. However, there was an inverse relationship between X5 and both ERV and VaSB. Hence the theoretical Xrs-volume relationship is present in COPD but only when considering the communicating volume rather than the absolute lung volume. These findings confirm the role of reduced communicating lung volume as an important determinant of Xrs and therefore advance our understanding and interpretation of FOT measurements in COPD. NEW & NOTEWORTHY To investigate the determinants of respiratory system reactance (Xrs) measured by the forced oscillation technique (FOT) in chronic obstructive pulmonary disease (COPD), we examine the relationship between Xrs and lung volume. We show that Xrs does not relate to absolute lung volume (functional residual capacity) in COPD but instead relates only to the volume of lung in communication with the airway opening. This communicating volume may therefore be fundamental to our interpretation of FOT measurements in COPD and other pulmonary diseases.
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Affiliation(s)
- Stephen Milne
- The Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research and Sydney Medical School, University of Sydney, Glebe, New South Wales , Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St Leonards, New South Wales , Australia.,Department of Respiratory Medicine, Concord Repatriation General Hospital, Sydney Local Health District, Concord, New South Wales , Australia
| | - Kanika Jetmalani
- The Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research and Sydney Medical School, University of Sydney, Glebe, New South Wales , Australia
| | - David G Chapman
- The Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research and Sydney Medical School, University of Sydney, Glebe, New South Wales , Australia.,Translational Airways Group, School of Life Sciences, University of Technology Sydney , Ultimo, New South Wales , Australia
| | - Joseph M Duncan
- Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St Leonards, New South Wales , Australia
| | - Claude S Farah
- The Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research and Sydney Medical School, University of Sydney, Glebe, New South Wales , Australia.,Department of Respiratory Medicine, Concord Repatriation General Hospital, Sydney Local Health District, Concord, New South Wales , Australia.,Faculty of Medicine and Health Sciences, Macquarie University , North Ryde, New South Wales , Australia
| | - Cindy Thamrin
- The Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research and Sydney Medical School, University of Sydney, Glebe, New South Wales , Australia
| | - Gregory G King
- The Woolcock Emphysema Centre and Airway Physiology and Imaging Group, Woolcock Institute of Medical Research and Sydney Medical School, University of Sydney, Glebe, New South Wales , Australia.,Department of Respiratory Medicine, Royal North Shore Hospital, Northern Sydney Local Health District, St Leonards, New South Wales , Australia.,Centre of Research Excellence in Severe Asthma, New Lambton, New South Wales , Australia
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Gholampour Y, Nourizadeh M, Adel MH, Eidani E, Amin A, Asadimoghadam M, Nourizadeh M, Nourizadeh S. Study the Effect of Spironolactone in Airway Resistance with Impulse Oscillometry in Patients with Congestive Heart Failure. Health (London) 2018. [DOI: 10.4236/health.2018.105053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Finding the best thresholds of FEV1 and dyspnea to predict 5-year survival in COPD patients: the COCOMICS study. PLoS One 2014; 9:e89866. [PMID: 24587085 PMCID: PMC3937394 DOI: 10.1371/journal.pone.0089866] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 01/24/2014] [Indexed: 12/11/2022] Open
Abstract
Background FEV1 is universally used as a measure of severity in COPD. Current thresholds are based on expert opinion and not on evidence. Objectives We aimed to identify the best FEV1 (% predicted) and dyspnea (mMRC) thresholds to predict 5-yr survival in COPD patients. Design and Methods We conducted a patient-based pooled analysis of eleven COPD Spanish cohorts (COCOMICS). Survival analysis, ROC curves, and C-statistics were used to identify and compare the best FEV1 (%) and mMRC scale thresholds that predict 5-yr survival. Results A total of 3,633 patients (93% men), totaling 15,878 person-yrs. were included, with a mean age 66.4±9.7, and predicted FEV1 of 53.8% (±19.4%). Overall 975 (28.1%) patients died at 5 years. The best thresholds that spirometrically split the COPD population were: mild ≥70%, moderate 56–69%, severe 36–55%, and very severe ≤35%. Survival at 5 years was 0.89 for patients with FEV1≥70 vs. 0.46 in patients with FEV1 ≤35% (H.R: 6; 95% C.I.: 4.69–7.74). The new classification predicts mortality significantly better than dyspnea (mMRC) or FEV1 GOLD and BODE cutoffs (all p<0.001). Prognostic reliability is maintained at 1, 3, 5, and 10 years. In younger patients, survival was similar for FEV1 (%) values between 70% and 100%, whereas in the elderly the relationship between FEV1 (%) and mortality was inversely linear. Conclusions The best thresholds for 5-yr survival were obtained stratifying FEV1 (%) by ≥70%, 56–69%, 36–55%, and ≤35%. These cutoffs significantly better predict mortality than mMRC or FEV1 (%) GOLD and BODE cutoffs.
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