Predicted normal values of pulmonary function tests in normal Korean children

PURPOSE: Pulmonary function tests are useful and important methods for evaluating patients with respiratory diseases. To assess lung function, we need to establish normal values of lung function, which vary according to population, age, gender and growth, particularly in children. This study was undertaken to establish normal predicted values of pulmonary function tests and to predict renewed reference values by spirometry in Korean school children. METHODS: Spirometric forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced expiratory flow at 25% to 75% of FVC (FEF25%-75%), and peak expiratory flow rate (PEFR) were measured in 406 healthy elementary school children (age, 6-12 years old) in May, 2012. Multiple linear regression analysis was performed for each spirometric parameter against age, height, weight and body surface area (BSA) separately for boys and girls, and derived reference equations and coefficients for all the spirometric parameters. RESULTS: All the measured spirometric parameters were significantly correlated with age, height, weight, and BSA. FVC was higher in boys aged 6-10 years than girls at ages matched. Height showed the highest correlation coefficient for all the spirometric parameters followed by BSA, weight and age in both genders. The normal predicted values of FVC and FEV1 at 130 cm in this study using renewed reference equations were approximately in the middle compared to previous studies. CONCLUSION: We reported here the renewed reference equations for normal predicted values of pulmonary function tests with high coefficients of determination based on updated data in healthy Korean children.

Dificultades en la elección de una ecuación de referencia para la interpretación de los resultados de capacidad de difusión de monóxido de carbono / Difficulties in the selection of a reference equation for the interpretation of the results of DLCO

Introduction: In the absence of national reference equations, the ATS recommends comparing the results of the diffusion capacity of healthy subjects in a representative sample of the population with international equations and choosing among them, the one that provides the lowest sum of the residues. Objective: To compare reference equations available in the literature and identify which best meets the selection criteria. Methods: We reviewed 10 reference equations, for each one we calculated the sum of the residues for a sample of 71 healthy subjects and described the characteristics that affect the variability of each one. Results: Since 1985 we have used the single breath method. Only Thompson et al prediction equations 2008 were obtained with instantaneous reading of CO. Equations with the lowest sum of residues (Miller, Roca and Cotes) include smokers and former smokers. Conclusions: We need an equation in non-smokers with methodology that ensures low variability.

Introducción: En ausencia de ecuaciones de referencia nacionales, la ATS recomienda comparar los resultados de capacidad de difusión de monóxido de carbono de sujetos sanos en una muestra representativa de la población, con ecuaciones internacionales y escoger entre estas, aquella que presente la menor suma de los residuos. Objetivo: Comparar las ecuaciones de referencia disponibles en la literatura e identificar cuál cumple mejor los criterios de selección. Método: Revisamos 10 ecuaciones de referencia; calculamos la suma de los residuos de cada una de ellas para una muestra de 71 sujetos sanos y describimos las características que inciden en la variabilidad de cada una. Resultados: Desde 1985 se ha utilizado el método de respiración única. Sólo las ecuaciones de Thompson y cols. 2008fueron obtenidas con lectura instantánea. Las ecuaciones que presentan menor suma de residuos (Miller, Roca y Cotes) incluyen fumadores y ex fumadores. Conclusiones: Es necesaria una ecuación nacional en sujetos sanos no fumadores, con metodología que asegure baja variabilidad.

Application of a New Spirometric Reference Equation and Its Impact on the Staging of Korean Chronic Obstructive Pulmonary Disease Patients

PURPOSE: A new spirometric reference equation was recently developed from the first national chronic obstructive pulmonary disease (COPD) survey in Korea. However, Morris' equation has been preferred for evaluating spirometric values instead. The objective of this study was to evaluate changes in severity staging in Korean COPD patients by adopting the newly developed Korean equation. MATERIALS AND METHODS: We evaluated the spirometric data of 441 COPD patients. The presence of airflow limitation was defined as an observed post-bronchodilator forced expiratory volume in one second/forced vital capacity (FEV1/FVC) less than 0.7, and the severity of airflow limitation was assessed according to GOLD stages. Spirometric values were reassessed using the new Korean equation, Morris' equation and other reference equations. RESULTS: The severity of airflow limitation was differently graded in 143 (32.4%) patients after application of the new Korean equation when compared with Morris' equation. All 143 patients were reallocated into more severe stages (49 at mild stage, 65 at moderate stage, and 29 at severe stage were changed to moderate, severe and very severe stages, respectively). Stages according to other reference equations were changed in 18.6-49.4% of the patients. CONCLUSION: These results indicate that equations from different ethnic groups do not sufficiently reflect the airflow limitation of Korean COPD patients. The Korean reference equation should be used for Korean COPD patients in order to administer proper treatment.

Selection of Reference Equations for Lung Volumes and Diffusing Capacity in Korea / 결핵및호흡기질환

BACKGROUND: The lung volume and diffusing capacity are influenced by ethnicity. However, there are no equations for predicting the normal lung volume in the adult Korean population, and there is only one equation for diffusing capacity. The aim of this study is to select the most suitable reference equation for the Korean population. METHOD: 30 men and 33 women at Hanyang University Guri Hospital, and 27 men and 34 women at Asan Medical Center in healthy nonsmoking adults were enrolled in this study. The subject's age, gender, height, weight, lung volume by plethysmography, and diffusing capacity by a single breathing method were obtained. The most suitable equation with the lowest sum of residuals between the observed and predicted values for lung volume and diffusing capacity was selected. RESULT: At Hanyang University Guri Hospital, the equations with the lowest sum of residuals in the total lung capacity were ECSC's equation in males (sum of residual: 0.04 L) and Crapo/Morris's equation (-1.04) in women. At the Asan Medical Center, the equations with the lowest sum of residuals in the total lung capacity were Goldman/Becklake's equation in males (sum of residual: -2.35) and the ECSC's equation -4.49) in women. The equations with the lowest sum of residuals in the Diffusing capacity were Roca's equation in males (sum of residual: -13.66 ml/min/mmHg) and Park's in women (25.08) in Hanyang University Guri hospital and Park's equation in all cases in the Asan Medical Center (male: -1.65 , female: -6.46). CONCLUSIONS: Until a reference equstion can be made for healthy Koreans by sampling, ECSC's equation can be used for estimating the lung volume and Park's can be used for estimating the diffusing capacity.

Effect of a New Spirometric Reference Equation on the Interpretation of Spirometric Patterns and Disease Severity / 결핵및호흡기질환

BACKGROUND: A spirometric reference equation was recently developed for the general population in Korea. The applicability of the new Korean equation to clinical practice was examined by comparing it with the Morris equation, which is one of the most popular reference equations used for interpreting the spirometric patterns and for grading the disease severity in Korea. METHODS: Spirometry was performed on 926 men and 694 women, aged 20 years or older, in November 2004 at the Asan Medical Center, Seoul, Korea. The subjects' age, gender, height, weight, and spirometric values (FEV1 [forced expiratory volume in one second], FVC [forced vital capacity], and FEV1/FVC) were obtained. The spirometric patterns and disease severity were evaluated using both equations, and the results of the Korean equation were compared with the Morris equation. The spirometric patterns were defined as normal, restrictive, obstructive, and undetermined according to the level of FEV1/FVC and FVC. The disease severity was defined according to the level of FEV1 level for subjects with an airflow limitation, and according to the FVC level for those subjects without an airflow limitation. RESULTS: Spirometric patterns were differently interpreted in 22.5% (208/926) of the men and 24.8% (172/694) of the women after the application of the Korean equation compared with the Morris equation. Of the subjects with airflow limitation, disease severity was differently graded in 30.2% (114/378) of the men and 39.4% (37/94) of the women after the application of the Korean equation. Of the subjects without airflow limitation, disease severity was differently graded in 27.9% (153/548) of the men and 30.2% (181/600) of the women after the application of the Korean equation. CONCLUSION: Achange in the reference equation for spirometry could have an effect on the interpretation of spirometric patterns and on the grading of disease severity.