• Tuberculosis and Respiratory Diseases
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• v.48 no.4
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• pp.522-529
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• 2000

Backgrounds : Assessment of the presence and degree of reversibility of airflow obstruction is clinically important in patients with asthma or chronic obstructive pulmonary disease. The measurement of peak expiratory flow(PEF) is a simple, fast, and cheap method to assess the severity of obstruction and its degree of reversibility. Assessing the reversibility of airflow obstruction by peak expiratory flow(PEF) measurements is practicable in general practice, but its usefulness has not been well investigated. We compared PEF and $FEV_1$ in assessing reversibility of airflow obstruction in patients with chronic obstructive pulmonary disease or asthma and developed a practical criterion for assessing the presence of reversibility in general practice. Methods : PEF measurements were performed (Spirometry) in 80 patients(aged 24-78) with a history of asthma or chronic obstructive lung disease before and after the inhalation of 200 g salbutamol. The change in PEF was compared with the change in forced expiratory volume in one second($FEV_1$). Reversible airflow obstruction was analyzed according to American Thoracic Society(ATS) criteria. Results : A 12% increase above the prebronchodilator value and a 200ml increase in either FVC or $FEV_1$ reversibility were observed in 45%(36) of the patients. Relative operating characteristic(ROC) analysis showed that an absolute improvement in PEF of 30 l/min gave optimal discrimination between patients with reversible and irreversible airflow obstruction(the sensitivity and specificity of an increase of 30 l/min in detecting a 12% increase above the prebronchodilator value and a 200ml increase in either FVC or $FEV_1$ were 72.2% and 72.7% respectively, with a positive predictive value of 68.4%). Conclusions : Absolute changes in PEF can be used to diagnose reversible airflow obstruction.

• Tuberculosis and Respiratory Diseases
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• v.56 no.2
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• pp.144-150
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• 2004

Background : An assessment of the presence and the degree of reversibility of airflow obstruction is clinically important in patients with asthma or chronic obstructive pulmonary disease. However, the time responses of spirometric parameters in response to bronchodilator have not been well investigated. Methods: We studied 15 patients with asthma. Spirometric and mini-Wright peak expiratory flow measurements were performed at 15, 30, 45, and 60 minutes after using single dose($200{\mu}g$) of inhaled bronchodilator, salbutamol. Results : The mean values of forced expiratory volume in one second($FEV_1$) and forced vital capicaty(FVC) were significantly increased at 60 minutes after using bronchodilator in comparison to 15 minutes. And peak expiratory flow rate measured by either mass flow sensor or mini-Wright peak flow meter were significantly increased at 45 minutes after using bronchodilator in comparison to 15 minutes. Conclusions : To appropriate evaluation of the bronchodilator response in patients with reversible airflow limitation, it would be useful measuring either $FEV_1$ or PEF at the later time point 60 or 45 minutes in comparison to 15 minutes after using bronchodilator.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1051-1062
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• 1997

Background : In asthma, airway obstruction is usually reversible, either spontaneously or with treatment. However, the responses to treatment are variable and some patients show an irreversible component of airflow obstruction. This may be associated with structural changes in the airway. To assess the relationship between the difference in airway reversibility and structural changes, we evaluated the HRCT findings and pulmonary function test. Methods : We studied 40 asthmatic subjects who had had acute exacerbation of symptoms and had showed normal chest X-ray findings. They had monitered PEFR daily, and had performed PFT and HRCT within three days after initiation of treatment. According to serial PEFR, they were grouped into 3 categories (Group 0 ; initial PEFR was within normal limit, Group 1 ; revealed increment of 30% in PEFR within 3 days after initiation of treatment, Group 2 ; revealed within 2 weeks) and then grouped again into 4 (Group 0, Group 3 ; reached to normal value of PEFR within 3 days after initiation of treatment, Group 4 ; within 2 weeks, Group 5 ; not within 2 weeks). Results : (1) Age in Group 0 was significantly lower than other groups(p<0.05), but there was no significance in other groups. (2) Duration of asthma in Group 2 was significantly longer than Group 0, 1(p<0.05). (3) FVC(%) and FEV1(%) were significantly decreased with delayed response to the treatment (p<0.05). (4) $FEV_1$/FVC(%) in Group 1, 2 were significantly lower than Group 0(p<0.05). $FEV_1$/FVC(%) in Group 5 was significantly lower than Group 0,3,4 (p<0.05). (5) Air trapping was increased significantly with delayed response to the treatment (p<0.05). (6) Mucus impaction in Group 0 was significantly larger than Group 1,2 (p<0.05). $FEV_1$/FVC(%) in Group 0,4,5 were significantly larger than Group 3 (p<0.05). Conclusion : Difference in reversibility of airway obstruction was associated with age, duration of asthma and severity of initial airflow obstruction There was no definite difference in HRCT findings in asthma.

• Tuberculosis and Respiratory Diseases
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• v.59 no.1
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• pp.23-29
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• 2005

Background : Chronic obstructive lung disease is characterized by smoke-related, gradually progressive, fixed airflow obstructions. However, some studies suggested that a reversible bronchial obstruction is common in chronic obstructive lung disease. Such reversibility persists despite the continued treatment with aerosolized bronchodilators and it appears to be related to the diminution in symptoms. The isolated volume response to a bronchodilator is defined as a remarkable increase in the FVC in response to the administration of a bronchodilator whereas the $FEV_1$ remains unchanged. This has been suggested in patients with severe emphysema. Therefore, the aim of this study was to determine the relationship between the response to a bronchodilator and the severity of an airflow obstruction in COPD patients using the GOLD classification. Methods : This study examined 124 patients with an airway obstruction. The patients underwent spirometry, and the severity of the airflow obstruction was classified by GOLD. The response groups were categorized by an improvement in the FVC or $FEV_1$ > 12%, and each group was analyzed. Results : Most subjects were men with a mean age of $65.9{\pm}8.5$ years. The mean smoking history was $41.26{\pm}20.1$ pack years. The isolated volume response group had relatively low $FEV_1$ and FVC values compared with the other groups. (p<0.001) Conclusion : In this study, an isolated volume response to a bronchodilator is a characteristic of a severe airway obstruction, which is observed in patient with a relatively poorer baseline lung function.

• Tuberculosis and Respiratory Diseases
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• v.42 no.3
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• pp.332-341
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• 1995

Background: Measurement of bronchodilator response is necessary to establish reversibility of airflow obstruction that was helpful to estimate the diagnosis, treatment, and prognosis in obstructive airway disease. An useful index should be able to detect the bronchodilator response more sensitively not related with degree of airflow obstruction and also be independent of initial $FEV_1$. Method: Sensitivities of bronchodilator response in each group classified by degree of airflow obstruction in $FEV_1$, FVC, $FEF_{25\sim75%}$, Isovolume $FEF_{25\sim75%}$, sGaw were studied and correlation coefficients were calculated between initial $FEV_1$ and reversibilities expressed as absolute, %initial, % predicted, %possible in $FEV_1$. Result: Sensitivities of bronchodilator response were 61.5% in FVC, Isovolume $FEF_{25\sim75%}$ and sGaw, in severe group, and 56.3% in Isovolume $FEF_{25\sim75%}$ and sGaw, in moderate group, and 62.5% in $FEV_1$ and sGaw and 50.0% in FVC and Isovolume $FEF_{25\sim75%}$, in mild group, and 60.0% in sGaw and 58.0% in Isovolume $FEF_{25\sim75%}$ in total patients. Correlation coefficients between initial $FEV_1$(L) and absolute, % initial, % predicted, % possible were 0.15, -0.22(p<0.05), 0.02, 0.24(p<0.05) and correlation coefficients between initial $FEV_1$(% predicted) and absolute, % initial, % predicted, %possible were 0.06, -0.28(p<0.05), 0.08, 0.39(p<0.05). Conclusion: Volume related parameters were more sensitive index not related with degree of airway obstruction and the change in $FEV_1$ expressed as % predicted was the least dependent on initial $FEV_1$ and reversibilities, expressed as % initial or as % possible(predicted minus initial $FEV_1$)were correlated with initial $FEV_1$.

• Tuberculosis and Respiratory Diseases
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• v.59 no.4
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• pp.374-379
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• 2005

Background : The single-breath carbon monoxide diffusion capacity (DLCO) and the per unit alveolar volume (KCO; $D_LCO/VA$) gave discordant values when there was an abnormal alveolar volume (VA). However, the clinical significance of the discordant values in patients with airflow limitation has not been examined. This study investigated the $D_LCO$ and KCO changes after improving the airflow limitation. Methods : The baseline $D_LCO$ and KCO with lung volume were measured in patients with an airflow obstruction. The effective alveolar volume was measured using the single-breath $CH_4$ dilution method. The patients divided into two groups according to the baseline values: (1) increased KCO in comparison with the $D_LCO$ (high discordance) (2) decreased or not increased KCO in comparison with the $D_LCO$ (low discordance). The diffusion capacity and lung volume were measured after treatment. Results : There was no significant difference in the baseline lung volumes including the $FEV_1$ and FVC between the two groups. The $FEV_1$ and FVC were significantly increased in the high discordance group compared with the low discordance group after treating the airflow limitation. The $D_LCO$ and alveolar volume were significant higher in the high discordance group compared with the low discordance group while the TLC was not. Conclusion : The discordance between the $D_LCO$ and KCO could be translated into an airflow reversibility in patients with an airflow limitation.

• Tuberculosis and Respiratory Diseases
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• v.72 no.1
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• pp.8-14
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• 2012

Background: Although airway obstruction in chronic obstructive pulmonary disease (COPD) is due to pathologic processes in both the airways and the lung parenchyma, the contribution of these processes, as well as other factors, have not yet been evaluated quantitatively. We therefore quantitatively evaluated the factors contributing to airflow limitation in patients with COPD. Methods: The 213 COPD patients were aged >45 years, had smoked >10 pack-years of cigarettes, and had a post-bronchodilator forced expiratory volume in one second ($FEV_1$)/forced vital capacity (FVC) <0.7. All patients were evaluated by medical interviews, physical examination, spirometry, bronchodilator reversibility tests, lung volume, and 6-minute walk tests. In addition, volumetric computed tomography (CT) was performed to evaluate airway wall thickness, emphysema severity, and mean lung density ratio at full expiration and inspiration. Multiple linear regression analysis was performed to identify the variables independently associated with $FEV_1$ - the index of the severity of airflow limitation. Results: Multiple linear regression analysis showed that CT measurements of mean lung density ratio (standardized coefficient ${\beta}$=-0.46; p<0.001), emphysema severity (volume fraction of the lung less than -950 HU at full inspiration; ${\beta}$=-0.24; p<0.001), and airway wall thickness (mean wall area %; ${\beta}$=-0.19, p=0.001), as well as current smoking status (${\beta}$=-0.14; p=0.009) were independent contributors to $FEV_1$. Conclusion: Mean lung density ratio, emphysema severity, and airway wall thickness evaluated by volumetric CT and smoking status could independently contribute to the severity of airflow limitation in patients with COPD.