• Clinical and Experimental Pediatrics
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• v.55 no.9
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• pp.330-336
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• 2012

Purpose: Fractional exhaled nitric oxide (FeNO) and forced expiratory flow between 25% and 75% of vital capacity ($FEF_{25-75}$) are not included in routine monitoring of asthma control. We observed changes in FeNO level and $FEF_{25-75}$ after FeNO-based treatment with inhaled corticosteroid (ICS) in children with controlled asthma (CA). Methods: We recruited 148 children with asthma (age, 8 to 16 years) who had maintained asthma control and normal forced expiratory volume in the first second ($FEV_1$) without control medication for ${\geq}3$ months. Patients with FeNO levels >25 ppb were allocated to the ICS-treated (FeNO-based management) or untreated group (guideline-based management). Changes in spirometric values and FeNO levels from baseline were evaluated after 6 weeks. Results: Ninety-three patients had FeNO levels >25 ppb. These patients had lower $FEF_{25-75}$ % predicted values than those with FeNO levels ${\leq}25$ ppb (P<0.01). After 6 weeks, the geometric mean (GM) FeNO level in the ICS-treated group was 45% lower than the baseline value, and the mean percent increase in $FEF_{25-75}$ was 18.7% which was greater than that in other spirometric values. There was a negative correlation between percent changes in $FEF_{25-75}$ and FeNO (r=-0.368, P=0.001). In contrast, the GM FeNO and spirometric values were not significantly different from the baseline values in the untreated group. Conclusion: The anti-inflammatory treatment simultaneously improved the FeNO levels and $FEF_{25-75}$ in CA patients when their FeNO levels were >25 ppb.

• Clinical and Experimental Pediatrics
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• v.51 no.3
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• pp.323-328
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• 2008

Purpose : Asthma is defined as chronic inflammation of the lower small airways, and bronchial hyperreactivity (BHR) is a pathophysiologic feature of asthma. It has been proposed that although there is no direct variable capable of assessing the small airways, a forced expiratory flow of between 25 and 75 percent ($FEF_{25-75}$) might be considered a more sensitive early marker of small airway obstruction than the forced expiratory volume in 1 second ($FEV_1$). Thus, we proposed that the presence and degree of positive responses to bronchial methacholine testing were related to the difference (DFF) and ratio (RFF) between $FEV_1$ and $FEF_{25-75}$ in asthmatic children. Methods : The subjects were 583 symptomatic children, including 324 children with BHR and 259 controls. Pulmonary function tests, methacholine challenge tests, and skin prick tests were performed, and the total eosinophil count, total serum IgE, and serum eosinophil cationic protein level were measured in all subjects. From a concentration-response curve, the methacholine concentration required to produce a decrease of 20% from post-saline $FEV_1$ was calculated ($PC_{20}$). Results : The median DFF and RFF values decreased in controls compared to subjects with bronchial hyperresponsiveness, and this trend was found in groups ranked by its severity. $PC_{20}$ had a negative correlation with DFF and RFF. Cutoff values of 0.5 for DFF and 1.042 for RFF were identified, and sensitivity and specificity were calculated. Conclusion : This study revealed that DFF and RFF might be predictive of bronchial hyperresponsiveness in the context of normal $FEV_1$ in children.

• The Korean Journal of Physiology
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• v.15 no.1
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• pp.37-43
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• 1981

In the present study, an effort was directed to elucidate the effect of the physical training on the pulmonary function. Twenty-four male athletics major students who have undergone regular physical training for more than five years were randomly chosen as the athletic subjects, and 12 regular male students who have not been engaged in any form of regular physical exercise or training were chosen as the non-athletic subjects, and a comparison was made between the two groups. The following were mainly observed by spirometry for the study; respiratory rate, tidal volume, vital capacity, maximum voluntary ventilation(MVV), forced expiratory volume for 1 second$(FEV_1)$, percent $FEV_1$ to forced vital capacity$(FEV_1%)$, forced expiratory flow for initial 1 liter$(FEF_{0.2-1.2}L)$, and forced mid-expiratory flow$(FEF_{\;25-75}%)$. The results obtained are summarized as follow. 1) The respiratory rate, tidal volume, and vital capacity showed no significant difference between athletes and non-athletes. The MVV in athletes was significantly (p<0.01) increased to $148.1{\pm}3.1\;L/min$ comparing with $118.3{\pm}9.1\;L/min$ in non-athletes. 2) $FEV_1$ was $3.310{\pm}0.070\;L$ in athletes and $2.779{\pm}0.104$ in non-athletes; $FEV_1%\;83.63{\pm}1.29%$ in athletes and $75.33{\pm}1.75%$ in non-athletes, both showing significant(p<0.01) increase in athletes. 3) $FEF_{0.2-1.2}L$ was $297.1{\pm}13.5\;L/min in athletes and $222.7{\pm}15.0\;L/min$ in non-athletes; $FEF_{\;25-75}%$ was $3.543{\pm}0.109\;L/sec$ in non-athletes, both showing significant(p<0.01) increase in athletes. 4) Some discussions were made on these results. The lung volumes showed no significant difference between the two groups. But MVV, $FEV_1$, $FEV_1%$, $FEF_{0.2-1.2}L$ and $FEF_{25-75}%$ in athletes were significantly(p<0.01) higher than in non-athletes. It is therefore concluded that the athletes have more powerful respiratory muscles, or higher compliance of the lung and thorax than the non-athletes.