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Improved spirometric detection of small airway narrowing: concavity in the expiratory flow–volume curve in people aged over 40 years
BACKGROUND AND OBJECTIVE: We have explored whether assessing the degree of concavity in the descending limb of the maximum expiratory flow–volume curve enhanced spirometric detection of early small airway disease. METHODS: We used spirometry records from 890 individuals aged ≥40 years (mean 59 years...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Dove Medical Press
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732561/ https://www.ncbi.nlm.nih.gov/pubmed/29263661 http://dx.doi.org/10.2147/COPD.S150280 |
Sumario: | BACKGROUND AND OBJECTIVE: We have explored whether assessing the degree of concavity in the descending limb of the maximum expiratory flow–volume curve enhanced spirometric detection of early small airway disease. METHODS: We used spirometry records from 890 individuals aged ≥40 years (mean 59 years), recruited for the Burden of Obstructive Lung Disease Australia study. Central and peripheral concavity indices were developed from forced expired flows at 50% and 75% of the forced vital capacity, respectively, using an ideal line joining peak flow to zero flow. RESULTS: From the 268 subjects classified as normal never smokers, mean values for post-bronchodilator central concavity were 18.6% in males and 9.1% in females and those for peripheral concavity were 50.5% in males and 52.4% in females. There were moderately strong correlations between concavity and forced expired ratio (forced expiratory volume in 1 second/forced vital capacity) and mid-flow rate (forced expiratory flow between 25% and 75% of the FVC [FEF(25%–75%)]; r=−0.70 to −0.79). The additional number of individuals detected as abnormal using the concavity indices was substantial, especially compared with FEF(25%–75%), where it was approximately doubled. Concavity was more specific for symptoms. CONCLUSION: The inclusion of these concavity measures in the routine reports of spirometry would add information on small airway obstruction at no extra cost, time, or effort. |
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