• Clinical and Experimental Pediatrics
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• v.45 no.5
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• pp.588-595
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• 2002

Purpose : The incidence of obesity has increased in Korea recently. Obesity leads to higher risks of hypertension, hyperlipidemia and insulin resistance. It also leads to risks of respiratory complications. This study was performed to see the effects of obesity on children's pulmonary functions and on developed bronchospasm after exercise loading according to their obesity degrees. Methods : 257 obese children and 150 non-obese children were enrolled. Obese children were divided into 3 groups by the obesity degrees. Pre- and post-exercise loading $FEV_1$(forced expiratory volume at one second), FVC(forced vital capacity) and PEFR(peak expiratory flow rate) were checked in all subjects. The percent predicted values of each parameter was compared according to obesity degrees and the differences between pre-exercise and post-exercise values. Results : The percent predicted value of $FEV_1$, FVC decreased only in the severe obesity group compared with those in the control group. However percent predicted PEFR declined according to obesity degrees. The percent predicted value of $FEV_1$, FVC and PEFR after exercise loading were much lower than those before exercise loading in all groups. Conclusion : As the degree of obesity was higher, the percent predicted value of pulmonary function was lower. And after exercise loading, as the degree of obesity was higher, the reduction of percent predicted value of pulmonary function was larger. Therefore the pulmonary function in obese children must be observed carefully. Further studies on the effects of pulmonary functions in obese children are necessary.

• Clinical and Experimental Pediatrics
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• v.52 no.11
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• pp.1267-1272
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• 2009

Purpose:We examined the ability of preschool aged children to meet the American Thoracic Society (ATS) and European Resiratory Society (ERS) goals for spirometry quality and tried to find out the major factor for improving the rate of success of spiromety test in this age group. Methods:Spirometry was performed in 2-6 aged 155 children with chronic cough or suspicious asthma with the recording of maneuver quality measures of forced expiratory time, end-of-test volume, back-extrapolated volume (Vbe), and forced vital capacity (FVC), as well as flow-volume curve. The subjects were tested several times and the two best results in each subject were selected. All criteria for quality control were suggested by ATS/ERS guidelines. The criteria for starting of the test was Vbe <80 mL and Vbe/FVC <12.5%. The criteria for repeatability of the test was that second highest FVC and FEV1 are within 100 ml or 10% of the highest value, whichever is greater. For the criteria for termination of the test for preschool aged children, we evaluated the flow-volume curve Results:As getting older, the success rate of spirometry increased and rapidly increased after 3 years old. Total success rate of the test was 59.4% (2 years old - 14.3%, 3 years old - 53.7%, 4 years old - 65.1%, 5 years old - 69.7%, 6 years old- 70.8%). The percentage of failure to meet the criteria for starting the test was 6.5%, repeatability of the test was 12.3% and end of the test was 31%. There was a significant difference only in age between success group and failure group. Evaluating the quality control criteria of previous studies, the success rate increased with age. Conclusion:About 60% of preschool aged children met ATS/ERS goals for spirometry test performance and the success rate was highly correlated with age. It is clearly needed that developing more feasible and suitable criteria for quality control of spirometry test in preschool aged children.

• Tuberculosis and Respiratory Diseases
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• v.66 no.3
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• pp.186-191
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• 2009

Background: Osteoporosis is a significant comorbidity in patients with chronic obstructive pulmonary disease (COPD). This study examined the prevalence and risk factors associated with osteoporosis in patients with COPD. Methods: The bone mineral densities (BMDs) of the lumbar spine and femoral bone were measured in 53 patients with clinically stable COPD and 41 age- and gender-matched control subjects showing a normal lung function. Osteoporosis was defined as a T-score $\leq$-2.5. The subjects' clinical characteristics and laboratory data were reviewed, and multiple logistic regression analysis was used to identify the risk factors associated with osteoporosis in COPD patients. Results: The prevalence of osteoporosis was 47% and 32% in the COPD patients and controls, respectively. In particular, using the femoral neck T-score, the prevalence of osteoporosis in COPD patients was higher than that in the controls (26% vs. 5%; p=0.006). The average T-score of the lumbar spine (p=0.025) and femoral neck of COPD patients were significantly lower than those of the controls (p=0.001). The forced expiratory volume in the 1 second ($FEV_1$) % predicted (p=0.019; odds ratio [OR], 0.955; 95% confidence interval [CI], 0.919-0.993) and age (p=0.024; OR, 1.144; 95% CI, 1.018-1.287) were independently associated with osteoporosis in patients with COPD. Conclusion: Using the femoral neck T-score, the prevalence of osteoporosis in patients with COPD was higher than the age-and gender-matched controls. A lower $FEV_1$ and older age further increase the risk of osteoporosis in patients with COPD.

• Tuberculosis and Respiratory Diseases
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• v.79 no.1
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• pp.22-30
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• 2016

Background: The purpose of this study was to document outcomes following withdrawal of a single inhaler (step-down) in chronic obstructive pulmonary disease (COPD) patients on triple therapy (long-acting muscarinic antagonist and a combination of long-acting ${\beta}2$-agonists and inhaled corticosteroid), which a common treatment strategy in clinical practice. Methods: Through a retrospective observational study, COPD patients receiving triple therapy over 2 years (triple group; n=109) were compared with those who had undergone triple therapy for at least 1 year and subsequently, over 9 months, initiated inhaler withdrawal (step-down group, n=39). The index time was defined as the time of withdrawal in the step-down group and as 1 year after the start of triple therapy in the triple group. Results: Lung function at the index time was superior and the previous exacerbation frequency was lower in the step-down group than in the triple group. Step-down resulted in aggravating disease symptoms, a reduced overall quality of life, decreasing exercise performance, and accelerated forced expiratory volume in 1 second ($FEV_1$) decline ($54.7{\pm}15.7mL/yr$ vs. $10.7{\pm}7.1mL/yr$, p=0.007), but there was no observed increase in the frequency of exacerbations. Conclusion: Withdrawal of a single inhaler during triple therapy in COPD patients should be conducted with caution as it may impair the exercise capacity and quality of life while accelerating $FEV_1$ decline.

• Tuberculosis and Respiratory Diseases
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• v.79 no.2
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• pp.91-97
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• 2016

Background: Chronic obstructive pulmonary disease (COPD) is sometimes complicated with pneumonia, but little is known about the risk factors that promote the development of pneumonia in COPD. These risk factors were evaluated in the present study. Methods: The data of 324 patients with COPD from a prospective multi-center observational cohort with obstructive lung disease were evaluated retrospectively. To identify risk factors for the development of pneumonia in COPD, the clinical and radiological data at enrollment and the time to the first episode of pneumonia were analyzed by Cox proportional hazard analysis. Results: The median follow-up time was 1,099 days and 28 patients (8.6%) developed pneumonia. The Cox analysis showed that post-bronchodilator forced expiratory volume in one second ($FEV_1$, % of predicted) and the computed tomography (CT) emphysema extent (inspiratory V950) were independent risk factors for the development of pneumonia (post-bronchodilator $FEV_1$: hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.94-1.00; p=0.048 and inspiratory V950: HR, 1.04; 95% CI, 1.01-1.07; p=0.01). Conclusion: Emphysema severity measured by CT and post-bronchodilator $FEV_1$ are important risk factors for the development of pneumonia in COPD.

• Tuberculosis and Respiratory Diseases
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• v.83 no.4
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• pp.276-282
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• 2020

Background: Flexible bronchoscopy is one of the essential procedures for the diagnosis and treatment of pulmonary diseases. The purpose of this study was to identify the risk factors associated with the occurrence of hypoxia in adults undergoing flexible bronchoscopy under sedation. Methods: We retrospectively analyzed 2,520 patients who underwent flexible bronchoscopy under sedation at our tertiary care university hospital in South Korea January 1, 2013-December 31, 2014. Hypoxia was defined as more than 5%-point reduction in the baseline percutaneous oxygen saturation (SpO₂) or SpO₂ <90% for >1 minute during the procedure. Results: The mean age was 64.7±13.5, and 565 patients developed hypoxia during the procedure. The mean sedation duration and midazolam dose for sedation were 31.1 minutes and 3.9 mg, respectively. The bivariate analysis showed that older age, a low forced expiratory volume in one second (FEV₁), use of endobronchial ultrasound, the duration of sedation, and the midazolam dose were associated with the occurrence of hypoxia during the procedure, while the multivariate analysis found that age >60 (odds ratio [OR], 1.32), a low FEV₁ (OR, 0.99), and a longer duration of sedation (>40 minutes; OR, 1.33) were significant risk factors. Conclusion: The findings suggest that patients older than age 60 and those with a low FEV₁ tend to develop hypoxia during the bronchoscopy under sedation. Also, longer duration of sedation (>40 minutes) was a significant risk factor for hypoxia.

• Clinical and Experimental Pediatrics
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• v.48 no.3
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• pp.327-332
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• 2005

Interstitial lung disease refers to a group of pulmonary disorders characterized by inflammation of the interstitium, derangements and loss of alveolar capillary units leading to disruption of alveolar gas exchange, which induces symptoms of restrictive lung disease. Cases of interstitial pneumonia in children are uncommon and mostly have unknown causes. We have experienced an 8-year old boy who had symptoms of cyanosis, dry cough, dyspnea and abrupt weight loss. He had not been exposed to organic dusts, allergens or any other systemic disease infections. Chest radiology showed diffuse ground glass opacity in both lung fields. High resolution computed tomography(HRCT) showed multiple small patchy areas of consolidation with an underlying ground glass appearance in both lungs. The pathologic findings of lung biopsy tissue showed patchy areas of interstitial fibrosis, alveolar obliteration and nodular fibrotic areas, strongly suggesting interstitial pneumonia. No specific finding of viral inclusion or any other evidence of infection was found under electromicroscopy. We used peak flow meters to compare functional improvement. Forced expiratory volume in one second ($FEV_1$) was decreased to 25 percent of predicted value. The boy was given treatment with prednisone and showed improvements in HRCT findings after two months. He was able to tolerate easy exercise in school and showed clinical improvements after one year of follow up.

• Journal of Chest Surgery
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• v.45 no.2
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• pp.110-115
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• 2012

Background: Pneumonectomy remains the ultimate curative treatment modality for destroyed lung caused by tuberculosis despite multiple risks involved in the procedure. We retrospectively evaluated patients who underwent pneumonectomy for treatment of sequelae of pulmonary tuberculosis to determine the risk factors of early and long-term outcomes. Materials and Methods: Between January 1980 and December 2008, pneumonectomy or pleuropneumonectomy was performed in 73 consecutive patients with destroyed lung caused by tuberculosis. There were 48 patients with empyema (12 with bronchopleural fistula [BPF]), 11 with aspergilloma and 7 with multidrug resistant tuberculosis. Results: There were 5 operative mortalities (6.8%). One patient had intraoperative uncontrolled arrhythmia, one had a postoperative cardiac arrest, and three had postoperative respiratory failure. A total of 29 patients (39.7%) suffered from postoperative complications. Twelve patients (16.7%) were found to have postpneumonectomy empyema (PPE), 4 patients had wound infections (5.6%), and 7 patients required re-exploration due to postoperative bleeding (9.7%). The prevalence of PPE increased in patients with preoperative empyema (p=0.019). There were five patients with postoperative BPF, four of which occurred in right-side operation. The only risk factor for BPF was the right-side operation (p=0.023). The 5- and 10-year survival rates were 88.9% and 76.2%, respectively. The risk factors for late deaths were old age (${\geq}50$ years, p=0.02) and low predicted postoperative forced expiratory volume in one second (FEV1) (< 1.2 L, p=0.02). Conclusion: Although PPE increases in patients with preoperative empyema and postoperative BPF increases in right-side operation, the mortality rates and long-term survival rates were found to be satisfactory. However, the follow-up care for patients with low predicted postoperative FEV1 should continue for prevention and early detection of pulmonary complication related to impaired pulmonary function.

• Tuberculosis and Respiratory Diseases
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• v.83 no.3
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• pp.234-241
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• 2020

Background: The fractional exhaled nitric oxide (FENO) test is useful in asthma patients. However, a few studies on its usefulness in chronic obstructive pulmonary disease (COPD) patients have been reported. We analyzed the FENO level distribution and clinical characteristics according to the FENO level in COPD patients. Methods: From December 2014 to June 2019, COPD patients who underwent pulmonary function and FENO tests at Chonnam National University Hospital were retrospectively evaluated for FENO, comorbidities, asthma history, blood eosinophil, and pulmonary function test. The high FENO group was defined as those with FENO level>25 parts per billion (ppb). Results: A total of 849 COPD patients (mean age, 70.3±9.4 years) were included. The mean forced expiratory volume at 1 second was 66.5±21.7% and the mean FENO level was 24.3±20.5 ppb. Patients with FENO ≤25 ppb were 572 (67.4%) and those with FENO >25 ppb were 277 (32.6%). Blood eosinophil percentage was significantly higher (4.2±4.8 vs. 2.7±2.5, p<0.001) in patients with the high FENO group than the low FENO group. The high FENO group revealed a significantly higher frequency of patients with blood eosinophil percentage >3% (46.9% vs. 34.8%, p=0.001) and asthma history (25.6% vs. 8.6%, p<0.001) than the lower FENO group. Asthma history, blood eosinophil percentage >3%, and positive bronchodilator response (BDR) were independent risk factors for the high FENO level (adjusted odds ratio [aOR], 3.85; p<0.001; aOR, 1.46; p=0.017; and aOR, 1.57, p=0.034, respectively) in the multivariable analysis. Conclusion: The FENO level distribution varied in COPD patients and the mean FENO value was slightly elevated. Asthma history, eosinophil percent, and positive BDR were independent risk factors for the high FENO level.

• Tuberculosis and Respiratory Diseases
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• v.86 no.3
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• pp.203-215
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• 2023

Background: Surgical resection is the standard treatment for early-stage lung cancer. Since postoperative lung function is related to mortality, predicted postoperative lung function is used to determine the treatment modality. The aim of this study was to evaluate the predictive performance of linear regression and machine learning models. Methods: We extracted data from the Clinical Data Warehouse and developed three sets: set I, the linear regression model; set II, machine learning models omitting the missing data: and set III, machine learning models imputing the missing data. Six machine learning models, the least absolute shrinkage and selection operator (LASSO), Ridge regression, ElasticNet, Random Forest, eXtreme gradient boosting (XGBoost), and the light gradient boosting machine (LightGBM) were implemented. The forced expiratory volume in 1 second measured 6 months after surgery was defined as the outcome. Five-fold cross-validation was performed for hyperparameter tuning of the machine learning models. The dataset was split into training and test datasets at a 70:30 ratio. Implementation was done after dataset splitting in set III. Predictive performance was evaluated by R² and mean squared error (MSE) in the three sets. Results: A total of 1,487 patients were included in sets I and III and 896 patients were included in set II. In set I, the R² value was 0.27 and in set II, LightGBM was the best model with the highest R² value of 0.5 and the lowest MSE of 154.95. In set III, LightGBM was the best model with the highest R² value of 0.56 and the lowest MSE of 174.07. Conclusion: The LightGBM model showed the best performance in predicting postoperative lung function.