Nihon rinsho. Japanese journal of clinical medicine
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Chronic obstructive pulmonary disease (COPD) is a disease state characterized by airflow limitation that is not fully reversible. The existence of airflow limitation can be determined by spirometry that measures the forced expiratory volume in one second (FEV1) and its ratio (FEV1/FVC) to the forced vital capacity (FVC). ⋯ Some of the other pulmonary function tests are useful for understanding the pathophysiology of COPD. These tests include the diffusing capacity measurement of carbon monoxide per liter of alveolar volume (DLco/VA), measurement of lung volume using the nitrogen washout technique and whole body plethysmography, and measurement of lung compliance.
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In the guideline proposed by WHO (GOLD) or by the Japanese Respiratory Society (RS), the diagnosis of COPD is simply made when FEV1/FVC (FEV %) of a given subject after inhalation of short-acting bronchodilator is below 70%. On the other hand, on grounds of measured FEV1/predicted FEV (%FEV1), the disease severity of COPD is categorized into four stages including I (mild), II (moderate), III (severe), and IV(very severe). ⋯ However, the above-mentioned criteria have many impediments as they are too simple for diagnosing and classifying COPD with a complicated pathophysiology. In this paragraph, the attempt is made not only to comment on the diagnosis criteria and classification of disease severity of COPD provided in GOLD and JRS guidelines but also to investigate the details of the impediments existing in both guidelines.
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Review
[CT imaging of COPD--importance of phenotyping (emphysema dominant and airway disorder dominant)].
We have been engaged in the analysis of the distribution of low attenuation area (LAA) representing emphysema, and the measurement of airway dimensions using CT images from the view point of phenotyping of COPD. (1) L AA% (area ratio of LAA to all lung area) did not correlate with reversibility to bronchodilators, whereas WA% (area ratio of bronchial wall to cross section of bronchus) positively correlated with reversibility. Thus, bronchodilators may be effective in proportional to the extent of airway disorders. (2) The incidence of Gc*1F(+) was significantly higher in patients with severe emphysema. ⋯ Furthermore, there were significant correlations between the body mass index and the CT measures of emphysema. These data demonstrate that emphysema-like changes are present in the lungs of patients who are chronically malnourished.