Lung Function Tests in Infants and Children

Lung function testing is an essential modality of investigation in children as it provides objective evidence of lung disease/ health. With advances in technology, various tests are available that can aid in the diagnosis of lung disease, assess the progression and response to therapy and document the lung development and evolving lung diseases in infants. This narrative review discusses lung function tests in infants and children. Currently, lung function tests can be performed in every age group, from neonates to the elderly. Spirometry and peak expiratory flow rate (PEFR) are the most employed tests in children more than six years of age. Spirometry helps diagnose and monitoring of both obstructive and restrictive diseases. There is a need for expertise to perform and interpret spirometry correctly. The forced oscillation technique (FOT) or impulse oscillometry (IOS) is done with tidal volume breathing and is feasible even in preschool children. Their utility is mainly restricted to asthma in children at present. Lung function tests can be performed in neonates, infants and children using infant pulmonary function test (PFT) equipment, although their availability is limited. Diffusion capacity for carbon monoxide (DLCO) is a valuable tool in restrictive lung diseases. Lung volumes can be assessed by body plethysmography and multiple washout technique. The latter can also assess lung clearance index. It is essential to perform and interpret the lung function test results correctly and correlate them with the clinical condition for optimum treatment and outcome.

Comparison of impulse oscillometry and pulmonary function test in assessment of bronchial asthma control in children / 中华实用儿科临床杂志

Objective:To compare and analyze the effects of impulse oscillometry (IOS) and pulmonary function test (PFT) in the assessment of asthma control in children.Methods:A cross-sectional study of 323 children with bronchial asthma who visited the outpatient pediatric clinic of Shandong Provincial Hospital Affiliated to Shandong First Medical University from March to December 2020 was conducted.The patients were divided into the control group (123 cases) and the uncontrolled group (200 cases) according to the Childhood Asthma Control Test (C-ACT) score.In both groups, PFT and IOS were performed.The PFT test included the forced expiratory volume in one second (FEV 1), force expiratory volume in one second/forced vital capacity (FEV 1/FVC), peak expiratory flow (PEF), the instantaneous forced expiratory flow at 50% of forced vital capacity (FEF 50), the instantaneous forced expiratory flow at 75% of forced vital capacity (FEF 75), and maximum mid expiratory flow (MMEF). In the IOS test, the total respiratory impedance at 5 Hz (Z5), respiratory resistance at 5 Hz (R5), respiratory resistance at 20 Hz (R20), reactance at 5 Hz (X5), respiratory resistance at 5 Hz-respiratory resistance at 20 Hz (R5-R20), reactance area (AX), and resonance frequency (Fres) were measured.The data obtained were analyzed statistically using SPSS 25.0 software. ANOVA or Mann- Whitney U rank-sum test was used to compare data between groups.Receiver′s operating characteristic (ROC) curves were drawn to determine the predictive value of PFT and IOS parameters for uncontrolled asthma. Results:(1) According to the comparison results of PFT indexes between the two groups of children with asthma, the levels of FEV 1, FEV 1/FVC, PEF, FEF 50, FEF 75, MMEF in the control group were all higher than those in the uncontrolled group [(104.41±12.38)% vs.(98.89±16.61)%, 100.50 (94.40, 103.50)% vs.96.00 (89.83, 101.88)%, (100.29±15.31)% vs.(93.19±18.43)%, 85.60(70.60, 96.60)% vs.72.35 (57.08, 91.10)%, 67.20 (53.60, 81.70)% vs.56.80 (41.10, 74.73)%, 80.70 (66.80, 95.10)% vs.69.50 (54.03, 90.05)%] (all P<0.01). (2) According to the comparison results of IOS indices between the two groups, the levels of Z5, R5, R20, R5-R20, X5, AX and Fres in the control group were lower than those in the uncontrolled group {68.58 (63.29, 77.43)% vs.81.27(70.93, 91.96)%, 68.91(62.94, 77.60)% vs.80.61 (70.02, 89.29)%, 75.78 (67.50, 87.55)% vs.82.97 (71.50, 95.50)%, 0.51 (0.43, 0.59) [kPa/(L·S)] vs.0.62 (0.53, 0.74) [kPa/(L·S)], 69.31 (59.93, 79.14)% vs.86.48 (70.00, 102.48)%, 1.11 (0.76, 1.60) kPa/L vs.2.14 (1.42, 2.85) kPa/L, 18.21 (16.06, 19.56) Hz vs.20.56 (18.92, 22.81) Hz} (all P<0.01). (3) In the control group, 31 children (25.20%) had pulmonary dysfunction.(4) In the uncontrolled group, 95 children (47.50%) had pulmonary ventilation dysfunction.Only 20 children (10.00%) had a R5 larger than 120% of the predicted value and/or a R20 larger than 120% of the predicted value.(5) According to the ROC analysis results of the IOS indices for predicting asthma exacerbations, all of the areas under the ROC (AUC) of Z5, R5, R5-R20, X5, AX and Fres were greater than 0.7.AX had the highest value in predicting asthma exacerbations (AUC=0.785, 95% CI: 0.735-0.835), with sensitivity of 78.50% and specificity of 64.20%.All of the AUCs of PFT indices were smaller than 0.7.FEF 50 and MMEF had the largest AUC. Conclusions:PFT and IOS have good sensitivity in evaluating the level of asthma control in children, and IOS has good value in predicting asthma exacerbations.AX has the highest predictive value for asthma exacerbations.Asthma control levels of children should be evaluated using not only subjective (such as C-ACT score) but also objective (e.g.PFT, IOS) indices.

The clinical application of impulse oscillometry in children with asthma / 国际儿科学杂志

Bronchial asthma is a common chronic respiratory disease in childhood.Lung function test is helpful for the diagnosis, treatment and dynamic monitoring of patients with asthma.Impulse oscillometry(IOS)has received more and more attention in the diagnosis and treatment of bronchial asthma because of its relatively simple operation requirements and the uniqueness of airway function detection.However, the clinical significance of IOS examination in clinical practice is not yet completely clear, and there is no consensus on clinical application.This article makes a review of IOS examination in the diagnosis, airway hyperreactivity test, asthma control and treatment of asthma in children, in order to help clinicians to make rational use of IOS examination.

Research progress in the application of impulse oscillometry and fractional exhaled nitric oxide in idiopathic pulmonary fibrosis / 中国医师杂志

Impulse oscillometry (IOS) and exhaled nitric oxide fraction determination (FeNO) are two detection methods to evaluate lung function, which can provide important functional information not captured in standardized lung function tests. These two methods may be promising disease assessment and detection tools for idiopathic pulmonary fibrosis (IPF). Therefore, it is necessary to standardize IOS and FeNO methods. This paper reviews the research progress of IOS and FeNO in IPF, and discusses the limitations of these two detection methods and their application value in IPF.

Value of impulse oscillometry technique in assessment of silicosis / 中国职业医学

OBJECTIVE: To investigate the value of impulse oscillometry(IOS) technique in the assessment of silicosis. METHODS: A judgment sampling method was used to select 90 patients with silicosis as the silicosis group, which includes 30 cases in each stage of silicosis(stage 1-3). Thirty workers with no exposure history to free silica dust were selected as the control group. All subjects underwent routine pulmonary function and IOS test. RESULTS: The total respiratory impedanceat at 5 Hz(Z5), reactance at 5 Hz(X5), airway resistance at 5 Hz(R5), airway resistance at 20 Hz(R20), difference of R5 and R20(R5-R20), low frequency reactance area(AX) and resonance frequency(Fres) were higher in silicosis group than those in control group(P<0.05). The above IOS indicators showed an upward trend with the higher stages of silicosis(P<0.05). X5 was positively correlated with forced vital capacity(FVC), one-second expiratory capacity(FEV_1), FEV_1/FVC(P<0.05). Z5, R5, R50-R20 and Fres were negatively correlated with FVC, FEV_1 and FEV_1/FVC(P<0.05). CONCLUSION: IOS detection is highly sensitive for early diagnosis of silicosis. The parameters of airway resistance in IOS is correlated with the parameters of ventilatory dysfunction in routine pulmonary function test, which is of great value for the evaluation of silicosis.

Mecânica respiratória de pacientes com obesidade mórbida / Respiratory mechanics of patients with morbid obesity

RESUMO Objetivo avaliar os diferentes componentes da resistência do sistema respiratório e a força muscular respiratória, bem como investigar a ocorrência de limitação de fluxo expiratório (LFE) de pacientes obesos mórbidos (OM) na posição sentada. Métodos a amostra foi composta de OM (IMC ≥ 40 kg/m2) e de indivíduos não obesos (NO) com IMC entre 18 e 30 kg/m2. O protocolo foi composto de: avaliação antropométrica e da função respiratória (espirometria, pressões inspiratória (PIM) e expiratória máximas (PEM) e oscilometria de impulso). Na comparação entre os grupos, foi utilizado o teste T para amostras não pareadas. As correlações foram avaliadas pelo teste de Pearson, e o nível de significância foi de 5%. Resultados Foram avaliados 50 OM (idade 40,0 ± 10,4 anos, 1,64 ± 0,09 m, 138,8 ± 33,6 kg e 50,7 ± 8,9 kg/m2), além de 30 NO (idade 37,6 ± 11,5 anos, 1,67 ± 0,09 m, 65,2 ± 10,3 kg e 23,2 ± 22 kg/m2). Os OM apresentaram maiores valores de resistência total, central, de vias aéreas, tecidual e periférica quando comparados aos NO. Nenhum paciente apresentou LFE. A circunferência abdominal se associou com variáveis espirométricas PIM e PEM. A relação cintura-quadril se correlacionou com variáveis de mecânica respiratória, além das espirométricas PIM e PEM. Conclusões pacientes com obesidade mórbida e sem padrão espirométrico obstrutivo apresentam aumento nas resistências total, de vias aéreas, periférica e tecidual do sistema respiratório quando comparados a não obesos. Esses indivíduos, entretanto, não apresentam limitação de fluxo expiratório e redução da força muscular respiratória.

ABSTRACT Objective To evaluate the different components of the resistance of the respiratory system, respiratory muscle strength and to investigate the occurrence of expiratory flow limitation (EFL) in patients with morbid obesity (MO) when seated. Methods The sample was composed of MO (BMI≥40 kg/m2) and non-obese individuals (NO) with a BMI between 18 and 30 kg/m2. The protocol consisted of the anthropometric assessment and the following measures of respiratory function: spirometry, maximal inspiratory and expiratory pressures (MIP and MEP, respectively) and impulse oscillometry. The group comparison was performed using T-test for unpaired samples. The correlations were evaluated by the Pearson test with a significance level of 5%. Results Fifty MO (age 40±10.4 years, 1.64±0.09 m, 138.8±33.6 kg and 50.7±8.9 kg/m2), and 30 NO (age 37.6±11.5 years, 1.67±0.09 m, 65.2±10.3 kg and 23.2±22 kg/m2) were evaluated. The MO showed higher values of total, peripheral, airways, tissue and central resistance when compared to the NO. No patient showed EFL. The waist circumference was associated with spirometric variables, MIP, and MEP. The waist-to-hip ratio was correlated to respiratory mechanics and spirometric variables, MIP, and MEP. Conclusion Morbidly obese patients with no obstructive spirometric pattern show increased total, airway, peripheral, and tissue respiratory system resistance when compared to nonobese. These individuals, however, do not present with expiratory flow limitation and reduced respiratory muscles strength.

Estandarización de la oscilometría de impulso y generación de ecuaciones piloto para generar valores de referencia en el Hospital Central Militar / Standardization of impulse oscillometry and the generation of pilot equations to generate reference values in the Central Military Hospital

Resumen Introducción La oscilometría de impulso es una prueba que evalúa la mecánica respiratoria a través de la aplicación de pequeños pulsos de presión que producen oscilaciones de flujo a una frecuencia determinada. Su aplicación relevante es en el estudio de las enfermedades de la vía aérea pequeña. El software integrado al equipo que ejecuta esta prueba genera cálculos de valores predictivos para cada uno de los parámetros oscilométricos, los cuales se basan en datos de población alemana. Objetivo Estandarizar la prueba de oscilometría de impulso y obtener ecuaciones piloto para valores de referencia. Material y métodos Se realizó un estudio experimental, analítico, prospectivo y longitudinal con sujetos voluntarios sanos. Se llevaron a cabo pruebas de espirometría y oscilometría de impulso basales y, tras broncodilatador, se registraron las impedancias, resistencias y reactancias del sistema respiratorio a 5, 10, 15 y 20 Hz. Los resultados se analizaron por sexo, edad, talla y peso. Se de 127 participantes sanos ingresaron al estudio, 51.5% del sexo efectuó un modelo de regresión lineal múltiple. Resultados Un total masculino (68) y 48.5% (64) del femenino, con edad promedio de 39.65 ± 15.26 años; la talla tuvo un promedio de 1.63 ± 0.09 m. Se demostró que el sexo influye en los valores de la oscilometría en el volumen corriente (VT), la impedancia, las resistencias y el área de reactancia (p < 0.05), y no afecta las reactancias (XRs) (p > 0.05); este parámetro está mayormente asociado a la talla (r = 0.727, r2 = 0.528). La edad incide en los valores de la oscilometría, ya que las resistencias (Rrs) son menores en los grupos más jóvenes; el IMC y el peso no comprometieron los valores de IOS. Conclusiones Este estudio proporciona ecuaciones piloto de referencia para los índices comunes de oscilometría de impulso en sujetos mexicanos. Así, integra una prueba de función pulmonar para facilitar la detección de alteraciones funcionales en vía aérea pequeña. Sugerimos realizar más trabajos en población mexicana, sobre todo de edad avanzada, para confirmar nuestros resultados y proporcionar una base más sólida a las ecuaciones de referencia para IOS, con un fin clínico y epidemiológico.

Abstract Introduction Impulse oscillometry is a test that evaluates the respiratory mechanics by the application of small pulses of pressure, which produce flow oscillations to a certain frequency. Its main application is in the study of the illnesses of the small airline. The integrated software of the test equipment generates predictive values for each of the oscillometric parameters, based on German population data. Objective To standardize the impulse oscillometry test in order to design pilot equations for reference values in our population. Material and methods We performed a pilot, experimental, analytical, longitudinal study with healthy volunteer subjects. Spirometry and impulse oscillometry tests were performed, both basal impedances, resistances, and reactances of the respiratory system to and after bronchodilator application; we measured and registered the 5, 10, 15, and 20 Hz. The results were analyzed by sex, age, height, and weight. The analysis was performed using a model of multiple linear retrogression. Results A total of 127 healthy participants were recruited, 51.5% men (68) and 48.5% (64) women, with an average age of 39.65 ± 15.26 years; their height was an average of 1.63 ± 0.09 m. It was proved that the gender influences the oscillometry values of tidal volume (VT), the impedance, the resistances and reactance area (p < 0.05), but not the reactances (XRs) (p > 0.05); this parameter is mainly associated with the size (r = 0.727, r2 = 0.528). The age influences the oscillometry values since the resistances (Rrs) are lower in the youngest groups; the BMI and the weight had no influence on the values of IOS. Conclusions This study provides pilot reference equations for the common indexes of impulse oscillometry in Mexican subjects, in order to integrate this test of pulmonary function to facilitate the detection of functional alterations in the small airline. We suggest more studies should be done on Mexican population, and especially on people of advanced age, to confirm our results and to provide a more solid base for the equations of reference to IOS, with clinical and epidemiologic purposes.

Application of impulse oscillometry in the measurement for childhood bronchial hyperresponsiveness / 中华实用儿科临床杂志

Objective To explore the effectiveness of impulse oscillometry(IOS)in airway responsiveness measurement and to find out the positive threshold of IOS for asthma diagnosis. Methods Seventy-nine children aged 6-14 years who had suspicious asthma,were recruited into the study. The positive criteria of the methacholine bron-chial provocation test was a 20％ reduction in forced expiratory volume in the first second (FEV 1 )compared to base-line. Simultaneously measured changes in various parameters of IOS,including resonant frequency(Fres),impedance at 5 Hz(Zrs),resistances at 5 and 20 Hz(R5,R20),reactance at 5 Hz(X5),and area of reactance(AX). The results of the challenge test were divided into positive and negative groups according to the pulmonary ventilation function me-thod. The differences between the 2 groups of IOS parameters before and after the challenge test,and the correlation be-tween the change rate of FEV1 and the change rate of IOS parameters were compared,and the positive judgment criteria of IOS parameters in the determination of respiratory responsiveness were determined. Results The positive group of bronchial provocation test had 37 patients and negative group had 42 patients. There was no significant difference in the basic values of parameters between the positive group and the negative group (all P > 0. 05). Changes in Zrs,R5,X5 of IOS were correlated with changes in FEV1 (r = 0. 374,0. 310,0. 449,all P < 0. 05). By single factor analysis,the area under the receiver operating characteristic(ROC)carve (AUC)showed:basic value of Zrs increased by 45. 85％,R5 increased by 45. 72％,X5 increased by 80. 74％ respectively compared to the baseline showed the optimal combination of sensitivity and specificity. In multivariate Logistic regression models,when Zrs and R5 were combined to measure the airway responsiveness,the sensitivity and specificity were 73. 0％ and 81. 0％,respectively. Conclusions IOS and spirometry can be used to determine airway responsiveness in children during methacholine bronchial challenge. Zrs≥45. 85％,or R5≥45. 72％,or X5≥80. 74％,or Zrs and R5 of multiple regression formula can be used as the positive criteria for young children with airway heperresponsiveness,the combination of Zrs and R5 has higher sensitivity and specificity.

Changes of airway resistance before and after Bronchial Diulation Test in patients with senile Asthma / 实用医学杂志

Objective To investigate the changes of airway resistance before and after Bronchial Diulation Test in patients with senile asthma and the effect of age on the degree of airway resistance. Methods A total of 29 (> 60 years)senile asthma patients and 21 younger( 60 years)and the group of healthy control(age < 60 years ). Each index of the airway resistance has a very good correlation with FEV1%,with the highest degree of relation is X5%. Conclusion The airway resistance of senile asthmatic patients was significantly improved after diuslation test and these indexes IOS would be valuable in evaluating the changes of airway resistance of senile asthma.

Reference Equations for Impulse Oscillometric and Respiratory System Model Parameters in Anglo and Hispanic Children / Ecuaciones de referencia para parámetros de oscilometría de impulsos y de modelo del sistema respiratorio en niños anglos e hispanos

Abstract The Impulse Oscillometry System (IOS) has been recognized as a useful diagnostic tool. Previous research by our group has shown that R5 (Resistance at 5 Hz), R5-R20 (frequency dependence of resistance), AX (the "Goldman Triangle") and the extended Resistor-Inductor-Capacitor (eRIC) model-derived parameter Cp (peripheral Compliance) are reliable measures that track respiratory system function. Here we determined the predictive equations from 112 asthmatic and non-asthmatic Anglo and Hispanic children data, that were previously classified into four groups: Normal, PSAI (Probable Small Airway Impairment), SAI (Small Airway Impairment), and Asthma by using regression analysis of IOS and eRIC model parameters as dependent variables regressed against age, height, and weight. Height showed the greatest correlation with IOS and eRIC model parameters and provided the most significant reference values for these measures in Anglo and Hispanic children. These values could serve as a useful framework for diagnosis, early interventions, and treatment of respiratory diseases in this population.

Resumen El Sistema de Oscilometría Impulsos (por sus siglas en Inglés: IOS) ha sido reconocido como una herramienta de diagnóstico útil. Investigaciones previas realizadas por nuestro grupo han demostrado que R5 (Resistencia a 5 Hz), R5-R20 (dependencia a la frecuencia de la resistencia), AX (el "Triángulo de Goldman") y el párametro Cp (Capacitancia periférica) derivado del modelo extendido Resistencia-inductor-condensador (eRIC) son medidas fiables que monitorean la función del sistema respiratorio. El presente estudio determina las ecuaciones de predicción de 112 niños Anglo e Hispanos asmáticos y no asmáticos, que previamente clasificados en cuatro grupos: Normal, PSAI (por su nombre en inglés: Probable daño en las vías aéreas menores), SAI (por su nombre en inglés: Daño en las vías aéreas menores), y Asma. Las ecuaciones de predicción se determinaron mediante análisis de regresión de parámetros del IOS y del modelo eRIC (variables dependientes) contra edad, estatura y peso. La estatura mostró la mejor correlación con los parámetros del IOS y del modelo eRIC, proporcionando los valores de referencia más significativos para estas medidas en niños Anglos e Hispanos. Estos valores podrían servir como un marco de referencia útil para el diagnóstico, intervenciones tempranas, y tratamiento de las enfermedades respiratorias en esta población.

Progress of impulse oscillometry in children / 国际儿科学杂志

Impulse oscillometry system(IOS) is a new pulmonary function test in recent years, IOS has been developed as a patient-friendly lung function test that minimizes demands on the patient, a noninvasive method without pain, the results is objective and comprehensive, suitable for all patients, especially for the elder ly, children, coma patients, pregnant women and critically ill patients, for better detection, diagnosis, and treat ment of different respiratory diseases.This article is to determine the reference values of IOS, its utility in children, the existing questions and its development prospect.

Application development of impulse oscillometry pulmonary function test in diagnosis and treatment of asthma in children / 中华实用儿科临床杂志

Impulse oscillometry(IOS) pulmonary function is a method with clinical value,and it plays important roles in diagnosis and evaluating treatment of asthma.IOS is sensitive and can discriminate the position of airway obstruction.IOS is easy to perform,and no special respiratory movements are required,so IOS is particularly suitable for children.IOS contributes great value on diagnosis and treatment of asthma in children,and it is a method with bright prospect.

Importancia de la función pulmonar en el diagnóstico y evaluación del asma en el menor de seis años / Pulmonary function assesment for asthma evaluation and diagnosis in childrens under six years

El asma es la enfermedad crónica más frecuente en la infancia. Para su diagnóstico, adecuada evaluación de su severidad y monitoreo de la respuesta al tratamiento, se requiere de la medición de la función pulmonar. En los últimos años se ha despertado un gran interés en el estudio de los preescolares, para lo cual se han desarrollado adaptaciones de la espirometría y técnicas como la oscilometría de impulso (IOS) y se han publicado estudios que muestran que es factible obtener espirometrías aceptables a esta edad y que en conjuntos con la IOS permiten diagnosticar y evaluar la gravedad del asma con mayor precisión que basados solamente en aspectos clínicos. Estos importantes avances son revisados a continuación.

Asthma is the most common chronic disease in childhood. For diagnosis, appropriate assessment of its severity and monitoring response to treatment, it requires the measurement of lung function. In recent years there has been a great interest in the study of preschool children, for which spirometry adaptations and impulse oscillometry (IOS) has been used and published studies show that it is possible to obtain acceptable spirometry at this age and in conjunction with the IOS to diagnose and assess the severity of asthma with greater precision than based solely on clinical aspects. These important advances are reviewed here.

The application and clinical significance of impulse oscillometry lung function in children with bronchial asthma / 中国医师进修杂志

Objective To investigate the clinical application and diagnostic value of impulse oscillometry lung function in children with bronchial asthma.Methods Thirty-two children (19 children in acute attack group,13 children in clinical remission group) with bronchial asthma were selected,and 20 healthy children as control group.The lung function simation by Master Screen impulse oscillometry device was detected.Results The outcome of the R5,R20,R5-R20,the negative of X5 and Fres in acute attack group (21.90±2.70) Hz]were higher than those in clinical remission group [(7.75±0.97),(3.82±0.50),outcome of the R5,R5-R20 and Fres in clinical remission group were higher than those in control group (P＜0.05),but there were no statistical significance in R20 and X5 in the two groups (P＞0.05).Conclusion Impulse oscillometry can provide various objective indicators to bronchial asthma in acute attack and clinical remission stage.which can be used as a method in detecting pulmonary function and monitoring therapy of bronchial asthmatic children.

Relationship between Exhaled Nitric Oxide Concentration and Pulmonary Function/Airway Hyperresponsiveness in Asthmatic Children / 소아알레르기및호흡기학회지

PURPOSE: Exhaled nitric oxide (eNO) has been proposed as a non-invasive marker for airway inflammation in asthma. Pulmonary function tests have been widely used in the diagnosis and management of asthma. Airway hyperresponsiveness (AHR) is one of the major features in asthma and usually assessed by the methacholine challenge test. The purpose of the present study was to assess the possible relationship between eNO and pulmonary function/AHR in asthmatic children. METHODS: There were 121 asthmatic children and 81 controls in the study. The eNO level was measured, the methacholline challenge test, spirometry, impulse oscillometry (IOS) and assessment of their bronchodilator responses were performed on all subjects. RESULTS: The asthma group had a higher eNO value than the control group [28.3 (15-55.75) vs. 20 (12.35-39.7) ppb, P=0.015]. The eNO level correlated positively with dFEV1 (r=0.230, P= 0.001). It correlate inversely with dR5 (r=-0.149, P=0.036), eNO with PC20 (r=-0.318, P<0.001) and with FEF25-75 (r=-0.17, P=0.015), but not with FEV1. CONCLUSION: This study suggests that eNO values may reflect AHR, as well as airway inflammation, but not pulmonary function.

A comparison between impulse oscillometry system and spirometry for spirometry for detecting airway obstruction in children / 소아과

PURPOSE: Measurement of forced expiratory volume in 1 second (FEV1) is usually difficult to obtain in children under six years of age because it requires active cooperation. This study evaluates the sensitivity of impulse oscillometry system (IOS) parameters for detecting airway obstruction in comparison with FEV1. METHODS: We studied 174 children who performed the lung function and methacholine challenge tests to diagnose asthma by IOS and spirometry. Children were divided into two subgroups according to their PC20, which is a parameter for bronchial sensitivity. We compared IOS parameters with FEV1 at the baseline, post-methacholine challenge, and evaluated their correlation. RESULTS: At the baseline, reactance at 5 Hz (X5) and resistance at 5 Hz (R5) significantly differed between the PC20 positive (PC2016 mg/mL) group; however, FEV1, FEV1% predicted, FEV1_Zs (Z score) did not differ. FEV1 is correlated with X5 (r=0.45, P<0.01) and R5 (r=-0.69, P<0.01). FEV1_Zs is also correlated with X5_Zs (r=-0.26, P<0.01) and R5_Zs (r=-0.31, P<0.01). After the methacholine challenge test, dose-response slopes in FEV1 and X5 significantly differed between the two subgroups (P<0.05). CONCLUSION: IOS parameters were more discriminative than FEV1 for detecting decreased baseline lung function between two subgroups and have a good correlation with FEV1.

Reference values for respiratory system impedance using impulse oscillometry in school-aged children in Korea / 소아과

PURPOSE: The impulse oscillometry (IOS) is applicable to young children because it requires minimal cooperation and a non-invasive method to measure the mechanics of respiratory system. This study aimed to develop the reference values in school-aged children in Korea, using IOS which is a modification of forced oscillation technique (FOT). METHODS: Measurements were performed in 92 previously untrained healthy children, aged 7 to 12 years old, using IOS. We analyzed the relationships between the data about their age, height, weight, body surface area (BSA), body mass index (BMI) and the result of IOS using the linear regression test. RESULTS: The success rate of IOS was 92.4%. Stepwise multiple regression of resistance of respiratory system (Rrs) and reactance of respiratory system (Xrs) in natural form for age, height, weight, BSA, BMI showed that height was the most significant predictor and altogether of 5 variables explained the Rrs and Xrs most. Our regression equations at multiple frequencys were comparable to published reference values, especially about the Rrs obtained at 5 Hz. CONCLUSION: IOS is a feasible method to measure the respiratory resistance in untrained children. We got the reference values using IOS and it seems to be useful to diagnose a variety of respiratory diseases.

Implication of impulse oscillometry in the measurement of bronchial hyperresponsiveness / 中国医师进修杂志

0.05) in the negative group. However, there was a significant increase in each parameter except Rc in the positive group (P

A Study on Respiratory Impedance of Patients with Obstructive Sleep Apnea-hypopnea Syndrome / 中国医师杂志

Objective To investigate the characteristics of respiratory impedance in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). Methods The impulse oscillometry(IOS) and polysomnography (PSG) indices were measured in 52 patients with OSAHS, 13 patients with chronic obstructive pulmonary disease (COPD) and 17 healthy persons. Results The levels of R20, total respiratory impedence and central airway resistance in the patients with OSAHS were significantly higher than those in healthy persons (P

Effect of Exercise on Pulmonary Function / 결핵

BACKGROUND: The effects of exercise on pulmonary function are complex and have been the subject of many investigations. But, there has been disputes about the effect of exercise on spirometric parameters and there is no study about the effect of exercise on IOS(Impulse Oscillometry)parameters. lOS, a new method of pulmonary funtion test, is based on the relationship between the pressure and flow oscillation which is produced by applying sinusoidal pressure oscillation to the respiratory system via the mouth. METHOD: Fifty-nine young adults without respiratory symptoms were divided into three groups according to degree of exercise(hard exercise group: mean exercise time is over three hours per week at least for the last one month, light exercise group: between thirty minutes to three hours, nonexercise group : less than thirty minutes) and undertaken pulmonary function test(simple spirometry and IOS). RESULTS: The effects of exercise on spirometric parameters ; percentage of predictive value of forced vital capacity(FVC % pred) was higher in hard exercise group than nonexercise group(hard exercise group:102.4+/-14.8, nonexercise group: 93.7+/-9.9, p= 0.017), but there was no significant diffetence in percentage of predicted value of forced expiratory volume in one second(FEV 1% prod) and percentage of predicted value of forced expiratory flow 50% (FEF 50% pred) between groups. The effects of exercise on LOS parameters : Reactance at 5Hz(X5) was significantly lower in hard exercise group than nonexercise group(hard exercise group: -0.166+/-0.123hPa/1/s, nonexercise group: 0.093+/-0.036hPa/1/s, p= 0.006) but there was no significant difference in central resistance(Rc), peripheral resistance(Rp), resonance frequency(RF) and resistance at 5Hz, 20Hz between groups. CONCLUSION: Hard exercise increased FVC % pred on spirometric parameters and decreased reactance at 5Hz (X5) on lOS parameters.