Impulse Oscillometry Parameters Research Articles

Impulse оscillometry in the diagnosis of moderate airway obstruction

Background: Impulse oscillometry (IOS) is a non-invasive method for determining respiratory impedance and its parameters. IOS has certain advantages over traditional spirometry.
 Aim: To assess the potential of IOS in the diagnosis of moderately severe airway obstruction.
 Methods: We examined 53 patients divided in two groups. The first group consisted of 29 patients (26 males and 3 females aged 42 to 89 years) with moderately severe obstructive abnormalities; the second group included 24 patients (17 males and 7 females aged from 18 to 68 years) without ventilatory defects.
 Results: Obstructive abnormalities were detected by IOS in 93% of patients in group 1, and the severity of obstruction was more pronounced compared to the results of spirometry in 37% of patients. In group 2, the IOS parameters were normal. There were significant differences in the lung function and IOS parameters between the first and second groups. There were significant correlations between airway resistance and IOS parameters in patients with moderately severe obstructive abnormalities.
 Conclusion: Thus impulse oscillometry can be used in the clinical practice to diagnose disorders of respiratory mechanics in patients with moderately severe airway obstruction.

Assessment of within-breath impulse oscillometry parameters in children with asthma.

Impulse oscillometry (IOS) measures respiratory resistance and reactance during tidal breaths and is a convenient tool for evaluation of lung function. Respiratory resistance and reactance can be measured separately during inspiration and expiration (inspiratory-expiratory analysis). We investigated the differences in inspiratory-expiratory measurements obtained using IOS between children with and without asthma. We analyzed 819 subjects aged 4-18 years, including asthmatic children (n = 600) and controls (n = 219). Asthma was diagnosed in accordance with the American Thoracic Society/European Respiratory Society guideline. Spirometry and IOS were performed in all subjects. In whole-breath analysis, the asthma group had higher resistance at 5 Hz (R5) and reactance area (AX) and lower reactance at 5 Hz (X5) than the control groups. In inspiratory-expiratory analysis, the asthma group showed increased expiratory R5 and AX and decreased expiratory X5 when compared with the control group. The absolute changes in R5, X5, and AX values between inspiration and expiration were greater in children with asthma than those in controls (0.138 ± 0.195 vs 0.102 ± 0.162, P = 0.014; -0.106 ± 0.200 vs -0.086 ± 0.434, P < 0.001 and 0.460 ± 11.63 vs 0.398 ± 2.88, P = 0.002, respectively). Inspiratory-expiratory IOS analysis differentiated asthmatic children from control subjects, reflecting airway narrowing on expiration in pediatric asthma. The changes in R5, X5, and AX between inspiration and expiration can be a useful index for diagnosis of asthma in children without assessment of the response to a bronchodilator.

Small Airway Disease in Pulmonary Hypertension-Additional Diagnostic Value of Multiple Breath Washout and Impulse Oscillometry.

Airways obstruction is frequent in patients with pulmonary hypertension (PH). Small airway disease (SAD) was identified as a major contributor to resistance and symptoms. However, it is easily missed using current diagnostic approaches. We aimed to evaluate more elaborate diagnostic tests such as impulse oscillometry (IOS) and SF6-multiple-breath-washout (MBW) for the assessment of SAD in PH. Twenty-five PH patients undergoing body-plethysmography, IOS and MBW testing were prospectively included and equally matched to pulmonary healthy and non-healthy controls. Lung clearance index (LCI) and acinar ventilation heterogeneity (Sacin) differed significantly between PH, healthy and non-healthy controls. Likewise, differences were found for all IOS parameters between PH and healthy, but not non-healthy controls. Transfer factor corrected for ventilated alveolar volume (TLCO/VA), frequency dependency of resistance (D5-20), resonance frequency (Fres) and Sacin allowed complete differentiation between PH and healthy controls (AUC (area under the curve) = 1.0). Likewise, PH patients were separated from non-healthy controls (AUC 0.762) by D5-20, LCI and conductive ventilation heterogeneity (Scond). Maximal expiratory flow (MEF) values were not associated with additional diagnostic values. MBW and IOS are feasible in PH patients both providing additional information. This can be used to discriminate PH from healthy and non-healthy controls. Therefore, further research targeting SAD in PH and evaluation of therapeutic implications is justified.

Breathing Hydrogen-Oxygen Mixture Decreases Inspiratory Effort in Patients with Tracheal Stenosis

Background: Hydrogen-oxygen mixture (H₂-O₂) may reduce airway resistance in patients with acute severe tracheal stenosis, yet data supporting the clinical use of H₂-O₂ are insufficient. Objectives: To evaluate the efficacy and safety of breathing H₂-O₂ in acute severe tracheal stenosis. Methods: Thirty-five consecutive patients with severe acute tracheal stenosis were recruited in this prospective self-control study. Air, H₂-O₂ and O₂ inhalation was given in 4 consecutive breathing steps: air for 15 min, H₂-O₂ (6 L per min, H₂:O₂ = 2: 1) for 15 min, oxygen (3 L per min) for 15 min, and H₂-O₂ for 120 min. The primary endpoint was inspiratory effort as assessed by diaphragm electromyography (EMGdi); the secondary endpoints were transdiaphragmatic pressure (Pdi), Borg score, vital signs, and impulse oscillometry (IOS). The concentration of H₂ in the ambient environment was obtained with 12 monitors. Adverse reactions during the inhalation were recorded. Results: The mean reduction in the EMGdi under H₂-O₂ was 10.53 ± 6.83%. The EMGdi significantly decreased during 2 H₂-O₂ inhalation steps (Steps 2 and 4) compared with air (Step 1) and O₂ (Step 3) (52.95 ± 15.00 vs. 42.46 ± 13.90 vs. 53.20 ± 14.74 vs. 42.50 ± 14.12% for Steps 1 through 4, p < 0.05). The mean reduction in the Pdi under H₂-O₂ was 4.77 ± 3.51 cmH₂O. Breathing H₂-O₂ significantly improved the Borg score and resistance parameters of IOS but not vital signs. No adverse reactions occurred. H₂ was undetectable in the environment throughout the procedure. Conclusions: Breathing H₂-O₂ may reduce the inspiratory effort in patients with acute severe tracheal stenosis and can be used for this purpose safely.

Lung Sound Analysis and the Respiratory Cycle Dependence of Impulse Oscillometry in Asthma Patients.

Objective A lung sound analysis (LSA) is useful for detecting airway inflammation and obstruction in patients with asthma. To elucidate the mechanism of LSA, we investigated the relationship between the exhalation-to-inhalation sound pressure ratio in the low frequency range between 100 and 195 Hz (E/I LF) and the respiratory cycle dependence of impulse oscillometry (IOS) parameters. Methods Asthma patients underwent IOS [resistance of the respiratory system at 5 Hz (R5) and 20 Hz (R20), the reactance area (AX), resonant frequency of reactance (Fres), and reactance of the respiratory system at 5 Hz (X5)], spirography, and an LSA. The correlation between the LSA-derived E/I LF values and the respiratory cycle dependence of the IOS parameters was analyzed. Patients Thirty-four patients with mild to moderate bronchial asthma, who had not received oral or inhaled corticosteroids and who had no episodes of rumbling or wheezing were examined. Results The E/I LF value was significantly correlated with the differences of the R5 and R5-R20 values between exhalation and inhalation (p=0.035 and p=0.050) in a multivariate analysis. Conclusion E/I LF appears to be an index that expresses the respiratory cycle dependence of asthma as well as IOS.

Application of impulse oscillometry in the measurement for childhood bronchial hyperresponsiveness

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 (FEV1)compared to baseline. 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 between 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. Key words: Impulse oscillometry; Child; Airway responsiveness

Impulse oscillometry and obesity in children

ObjectiveTo compare impulse oscillometry system parameters of normal‐weight children with overweight and obese children. MethodAll participants were submited to the evaluation of lung function (spirometry and impulse oscillometry) following the American Thoracic Society standards. The evaluation of respiratory mechanics was performed using the JaegerTM MasterScreenTM Impulse Oscillometry System (Erich Jaeger, Germany), three tests were recorded, with acquisition for at least 20 seconds. ResultsThe study included 81 children (30 in the control group, 21 in the overweight group, and 30 the in obesity group), matched for age and sex. Regarding spirometry data, obesity group showed higher numerical values in relation to the control group; however, there were no significant differences among the three groups. For impulse oscillometry parameters, there was a difference between control group and obesity group for respiratory impedance (p=0.036), resistance at 5hertz (p=0.026), resonant frequency (p=0.029), and reactance area (p=0.014). For the parameters expressed in percentage of predicted, there were differences in resistance at 5 hertz, resonant frequency and reactance area between control group and obesity group. ConclusionsObese children showed increased oscillometry parameters values representative of airway obstruction, compared to normal‐weight children. Changes in some oscillometry parameters can already be observed in overweight school‐aged children.

Passive exposure to e-cigarette emissions: Immediate respiratory effects.

INTRODUCTIONThe present work examined the effect of passive exposure to electronic-cigarette (e-cigarette) emissions on respiratory mechanics and exhaled inflammatory biomarkers.METHODSA cross-over experimental study was conducted with 40 healthy nonsmokers, 18–35 years old with normal physical examination and spirometry, with body mass index <30 kg/m2, who were exposed to e-cigarette emissions produced by a smoker, according to a standardized protocol based on two resistance settings, 0.5 ohm and 1.5 ohm, for e-cigarette use. All participants underwent a 30-minute control (no emissions) and two experimental sessions (0.5 and 1.5 ohm exposure) in a 35 m3 room. The following Impulse Oscillometry (IOS) parameters were measured at pre and post sessions: impedance, resistance, reactance, resonant frequency (fres), frequency dependence of resistance (fdr=R5–R20), reactance area (AX), and fractional exhaled nitric oxide (FeNO). Differences between pre and post measurements were compared using t-tests and Wilcoxon signed rank tests, while analysis of variance (ANOVA) was used for comparisons between experimental sessions (registered under ClinicalTrials.gov ID: NCT03102684).RESULTSIOS and FeNO parameters showed no significant changes during the control session. For IOS during the 1.5 ohm exposure session, fres increased significantly from 11.38 Hz at baseline to 12.16 Hz post exposure (p=0.047). FeNO decreased significantly from 24.16 ppb at baseline to 22.35 ppb post exposure in the 0.5 ohm session (p=0.006).CONCLUSIONSA 30-minute passive exposure to e-cigarette emissions revealed immediate alterations in respiratory mechanics and exhaled biomarkers, expressed as increased fres and reduced FeNO.

Effect of inhaled corticosteroids on small airways in asthmatics using impulse oscillometry

Background The abnormalities in the small airways contribute to the symptoms of asthma. The small airways dysfunction may be attributed to many factors; mainly inflammation, remodeling, and changes in the surrounding tissue. Small airways affection associates with worse control of asthma, more frequent exacerbations, presence of nocturnal symptoms, more severe bronchial hyper-responsiveness, exercise-induced asthmatic symptoms, and the late-phase allergic response. Forced oscillation technique (FOT) was found to have higher sensitivity to inhaled corticosteroid (ICS) or to β-agonist inhalation than spirometry. Both ICS and β-agonists improve small-airway function, and FOT responses manifest eminent changes in indices of peripheral airway obstruction. In contrast, spirometric sensitivity to small-airway function is less eminent. Accordingly, it is expected that FOT might provide useful indices of peripheral airway change in response to therapeutic interventions. Aim The aim of this study was to evaluate the effect of regular use of ICS on small-airway function of asthmatic patients using impulse oscillometry (IOS). Patients and methods The study was carried out at Kobry El-Qobba Military Chest Hospital on 30 patients newly diagnosed as having mild and moderate bronchial asthma. Spirometric lung functions and IOS were done at baseline and then after 1 and 3 months of regular use of proper dosage of ICS to assess the effect on small-airway function. Results Results revealed that there was highly statistically significant improvement regarding changes in forced expiratory volume in 1 s, forced vital capacity, forced expiratory volume in 1 s/forced vital capacity, and maximum mid-expiratory flow (MMEF) 25–75 when comparing 1 day, 1 month, and 3 months. Moreover, there was statistically significant improvement regarding the R5, R20, and X5 when comparing 1 day, 1 month, and 3 months. Regular ICS use provides progressive improvement over time in both spirometry and IOS parameters. Both spirometric and IOS parameters were equally sensitive in detecting change of small-airway function. Conclusion Small-airway involvement in the pathogenesis of asthma will no longer be missed as it can be measured either qualitatively, as the presence or absence of high peripheral resistance values, or quantitatively through measuring the reactance. The more the patient is adherent to his or her daily recommended dose of ICS, the more evident is the improvement in his or her IOS and spirometric parameters including parameters that measure the small airways affection, starting from the very first few weeks of proper treatment. Using IOS is equally sensitive as spirometry in diagnosis and follow-up of adult asthmatic patients.

Impulse oscillometry in evaluation bronchial hyperresponsivness in patients with persistent allergic rhinitis

Background/Aim. Impulse oscillometry (IOS) is a method for estimating lung function which is used for early detection of bronchial hyperresponsiveness (BHR) and asthma. The aim of the study was to determine the prevalence of BHR, the correlation between spirometry and IOS and sensitivity and specificity of IOS in proving BHR in patients with persistent allergic rhinitis. Methods. The study included 81 patients with allergic rhinitis. From all of them, medical history was taken, allergy testing was done, as well as measurements of parameters of lung function by the IOS and spirometry before and after nonspecific bronchial provocation test with histamin via Aerosol provocative system. Changes of the IOS parameters to fall in FEV1 of 20% were measured and compared with changes in the spirometry parameters. After bronchial challenge test subjects were divided into two groups: the group with BHR (group 1) and that without BHR (group 2). Results. The mean age of participants was 25.7 ? 5.7 years, and 50.5% were men. Out of the total number of subjects with allergy rhinitis, 56 (58.9%) had a positive BPT. After bronchoprovocation an average increase in the group 1 was 88.15% for Rrs5, 111.98% for Fres, and for AX 819.69%. The high degree of correlation between the IOS and spirometry was proven in the group 2, while the whole group 1 had a weak correlation between parameters of these two methods. High sensitivity and low specificity for Rrs5 and Fres compared to FEV1 in diagnosing BHR was proven. Conclusion. The study demonstrated a high prevalence of BHR in the study group of patients with persistent allergic rhinitis, poor correlation in relation to the spirometric measurements in the group with BHR and a high sensitivity and low specificity of IOS for the detection of early changes in the airways.

Assessment of functional tests on determining resistance of respiratory tract in patients with bronchial asthma, COPD and their combination.

The mechanical properties of the respiratory tract (including airway resistance) is an important indicator of pulmonary function, and definition of resistance is used to diagnose and monitor obstructive lung diseases. This study was performed in order to evaluate and compare functional results of tests to determine the resistance of the airways in patients with asthma, chronic obstructive pulmonary disease and their combination. The study involved 191 patients: with asthma (n=34), with COPD (n=17) and their combination (n=140). Patients underwent bodyplethysmography and impulse oscillometry. A statistically significant correlation of medium strength between parameters of the total resistance, determined with the help of bodyplethysmography and impulse oscillometry, r=0.57, p&lt;0.001. According to ROC-analysis, the best point of distribution of normal and pathological parameters of impulse oscillometry (R5Hz) as a diagnosis of increased respiratory resistance is 130% and higher from the proper values. The area under the ROC curve is 0.807. When interpreting the results of impulse oscillometry in patients with asthma, COPD and their combination, R5Hz level equal to or exceeding 130% of the proper values is proposed to be regarded as a sign of an increased respiratory resistance with sensitivity of technique – 64.0%, specificity – 87.5% and prognostic value of the positive result - 98.2%.

Impulse oscillometry and obesity in children

ObjectiveTo compare impulse oscillometry system parameters of normal-weight children with overweight and obese children. MethodAll participants were submitted to the evaluation of lung function (spirometry and impulse oscillometry) following the American Thoracic Society standards. The evaluation of respiratory mechanics was performed using the Jaeger™ MasterScreen™ Impulse Oscillometry System (Erich Jaeger, Germany), three tests were recorded, with acquisition for at least 20seconds. ResultsThe study included 81 children (30 in the control group, 21 in the overweight group, and 30 the in obesity group), matched for age and sex. Regarding spirometry data, obesity group showed higher numerical values in relation to the control group; however, there were no significant differences among the three groups. For impulse oscillometry parameters, there was a difference between control group and obesity group for respiratory impedance (p=0.036), resistance at 5hertz (p=0.026), resonant frequency (p=0.029), and reactance area (p=0.014). For the parameters expressed in percentage of predicted, there were differences in resistance at 5 hertz, resonant frequency, and reactance area between control group and obesity group. ConclusionsObese children showed increased oscillometry parameters values representative of airway obstruction, compared to normal-weight children. Changes in some oscillometry parameters can already be observed in overweight school-aged children.

Small airway oscillometry indices: Repeatability and bronchodilator responsiveness in young children.

The impulse oscillometry (IOS) indices absolute and relative difference between respiratory resistance at 5 and 20 Hz (R5-20 and R5-20%, respectively) and the area under the reactance curve (AX) are postulated to reflect small airway function. Data on their cutoff values to evaluate bronchodilator responsiveness (BDR) or between-visit changes after interventions are limited in young children. We evaluated the BDR of 103 healthy children aged 2-7 years, who received either salbutamol (n = 84) or placebo (n = 19) in order to determine cutoff values for BDR of R5-20, R5-20%, and AX. We then determined the repeatability within and between two IOS measurements 7-14 days apart in young children aged 4-8 years with asthmatic symptoms (n = 43), including cutoff values for significant between-visit changes. The investigated IOS parameters showed marked BDR (fifth percentile cutoff of 75-110% of the baseline value) in healthy children, whereas no significant changes were seen after inhalation of placebo. The agreement within the triplicate IOS measurement was excellent (ICC > 0.80), and the agreement of results between visits was good (ICC > 0.60). A change in R5-20, R5-20%, and AX of 0.65, 1.08, and 0.84 z-scores, respectively, would exceed 95% confidence intervals for between-visit variability. We introduce cutoff values for BDR of R5-20, R5-20%, and AX, and their repeatability indices and cutoff limits for significant between-visit changes. These IOS parameters may show greater variability than the conventional IOS indices during follow-up, but the between-visit agreement remains good, providing potentially useful endpoints for monitoring lung function in young children.

Impulse oscillometry, spirometry, and passive smoking in healthy children and adolescents

ObjectiveTo identify changes in the forced and quiet breathing parameters of lung function in healthy children and adolescents exposed to passive smoking (PS). MethodComparative cross-sectional study. Healthy schoolchildren aged 6 to 14 years. We collected anthropometric data, lung function parameters using spirometry (forced breathing), and quiet breathing parameters using impulse oscillometry. The sample was divided into two groups according to exposure to PS: passive smoking group (PSG) and non-passive smoking group (NPSG). For the statistical analysis, the Shapiro–Wilk test was used to verify data normality and the T-test or Mann–Whitney test to compare spirometric and oscillometric parameters between groups (p≤0.05). Main findingsThe study included 78 children and adolescents, with 14 boys and 25 girls in each group. There were differences in the mean values for peak expiratory flow (p=0.01). There were no significant differences between the groups in values for z-score and lower limit of normal. The PSG had higher mean absolute values for reactance area (X5=0.05) and significant percentage of predicted values for the following impulse oscillometry parameters: central airway resistance (R20%, p=0.03) and for the indicators of presence of airway obstruction (Fres%, p=0.01; X5%=0.01% and AX%, p=0.01). ConclusionChildren and adolescents exposed to PS had lower values for the spirometric variables and higher values for the oscillometric variables, indicating changes in forced and quiet parameters of lung function compared to the NPSG.

Bronchodilator Response Assessment of the Small Airways Obstructive Pattern.

Background:A concomitant decrease in FEV1 and FVC with normal FEV1/FVC ratio and TLC defines small airways obstructive pattern (SAOP) and constitutes a classic pitfall of pulmonary-function-tests interpretation.Objective:To evaluate the prevalence of flow- (FEV1 increase≥12% and 200 mL), volume- (FVC or inspiratory capacity [IC] increase≥12% and 200 mL), flow and volume-, and non-response to bronchodilation in patients with SAOP. An additional objective was to assess whether impulse oscillometry (IOS) parameters allow the diagnosis of SAOP and its reversibility.Methods:Fifty consecutive adult patients with SAOP (FEV1 and FVC < lower limit of normal, FEV1/FVC and TLC > lower limit of normal) diagnosed on spirometry and plethysmography underwent the assessment of reversibility (400 µg salbutamol) on FEV1, FVC, IC and IOS parameters.Results:The diseases most frequently associated with SAOP were COPD and asthma (26 and 15 patients, respectively). Six patients were flow-responders, 20 were volume-responders, 9 were flow and volume-responders and 15 patients were non-responders. Overall, 26 patients had a significant improvement of IC, and 35 / 50 (70%, 95%CI: 57-83) exhibited a significant bronchodilator response. The difference between Rrs5Hz and Rrs20Hz was increased in 28/50 patients (56%, 95%CI: 42-70 with value higher than upper limit of normal) and its decrease after bronchodilator significantly correlated to FEV1 increase only, suggesting proximal airway assessment.Conclusion:A significant reversibility, mainly assessed on IC increase, is frequent in Small Airways Obstructive Pattern. Impulse oscillometry is of limited value in this context because of its low sensitivity.

An informative value of impulse oscillometry for diagnosis of ventilation abnormalities in patients with newly diagnosed pulmonary sarcoidosis

The aim of this study was to analysis the total respiratory impedance and its components and to evaluate the informative value of impulse oscillometry in comparison with conventional methods of lung function testing in patients with pulmonary sarcoidosis. Methods . The study involved 50 patients (88% of males; mean age, 31 ± 9 years) with newly diagnosed pulmonary sarcoidosis. The diagnosis of sarcoidosis was confirmed by lung biopsy. Spirometry, body plethysmography, and impulse oscillometry were used in all patients; the lung diffusing capacity was measured. Results . Abnormalities of the respiratory mechanics were found using the conventional diagnostic methods in 34% of the patients, including obstructive disorders in 18% and restrictive disorders in 16%; all were mild to moderate. Parameters of impulse oscillometry were abnormal only in 10% of the patients. Conclusion . The impulse oscillometry has a low sensitivity to detect mild functional respiratory abnormalities in patients with newly diagnosed pulmonary sarcoidosis.

A 12‐week, randomized, parallel‐group, proof‐of‐concept study of tulobuterol patch and salmeterol inhaler as add‐on therapy in adult‐onset mild‐to‐moderate asthma

Patch formulation of tulobuterol has been used in asthma treatment as a long-acting β2 -agonist (LABA) through sustained skin absorption. Its treatment efficacy, especially in small airways, remains poorly understood. The study aim was to investigate LABA add-on effects of tulobuterol patch (TP) and salmeterol inhaler (SA) on pulmonary function, asthma control and health status. Patients who had adult-onset under-control asthma, despite taking inhaled corticosteroids, were enrolled in a randomized, open-label, parallel-group, proof-of-concept study of 12-week add-on treatment with TP (n=16) or SA (n=17). Spirometry, impulse oscillometry (IOS), exhaled nitric oxide levels, and clinical questionnaires of asthma control, health status (St. George's Respiratory Questionnaire: SGRQ), and symptoms were evaluated every 4weeks. Add-on treatment of SA significantly improved the spirometric indices of small airway obstruction (forced expiratory flow between 25% and 75% of FVC: FEF25-75 , and maximum expiratory flow at 25% of FVC: MEF25 ) and IOS indices of whole respiratory resistance (resistance at 5Hz) as compared to TP. In intra-group comparisons, add-on treatment of TP improved the scores of the asthma control test and the total SGRQ, as well as the symptom and impact components of the SGRQ. SA add-on treatment improved FEV1 and IOS parameters of resistance at 20Hz and reactance at 5Hz. Neither of the treatments improved exhaled nitric oxide levels. In conclusion, add-on treatment of TP improved asthma control and health status, whereas SA improved pulmonary function measures associated with large and small airway involvement among patients with adult-onset mild-to-moderate asthma.

Sensitivity of newly defined impulse oscillometry indices in preschool children.

Early origins of chronic obstructive pulmonary disease have been recognized. Impulse oscillometry (IOS) is suitable for assessment of lung function also in preschool children, and some novel indices have been connected to assessment of small airway function. However, limited data exist on the sensitivity of these new indices to detect lung function deficits in young symptomatic children. IOS measurements of 103 healthy preschool children were evaluated to establish reference equations for the difference between respiratory resistance at 5 and 20 Hz (R5-20), the relative difference of R5-20 (R5-20%), and area under the reactance curve (AX). Thereafter, IOS results of children with late-onset troublesome lung symptoms (n = 20), a history of early wheeze (n = 37), or a history of bronchopulmonary dysplasia (BPD, n = 8) were compared to healthy children. None of the patient groups differed from healthy regarding respiratory resistance at 5 Hz (R5), and only children with a history of BPD differed from healthy regarding respiratory reactance at 5 Hz (X5). In contrast, z-scores of R5-20, R5-20%, and AX were significantly higher in all patient groups than in healthy children (P < 0.001), showing improved sensitivity (20-55%) compared to R5 and X5 (5-6%). R5-20, R5-20%, and AX are superior to conventional IOS parameters in distinguishing children with current or past lower respiratory tract symptoms from healthy, and may prove valuable for screening early lung function deficits. Pediatr Pulmonol. 2017;52:598-605. © 2016 Wiley Periodicals, Inc.

Diagnostic value of a pattern of exhaled breath condensate biomarkers in asthmatic children

BackgroundDiagnosing asthma in children is a challenge and using a single biomarker from exhaled breath condensate (EBC) showed the lack of improvement in it. ObjectiveThe aim of this study was to assess the diagnostic potential of a pattern of simple chemical biomarkers from EBC in diagnosing asthma in children in a real-life setting, its association with lung function and gastroesophageal reflux disease (GERD). MethodsIn 75 consecutive children aged 5–7 years with asthma-like symptoms the following tests were performed: skin prick tests, spirometry, impulse oscillometry (IOS), exhaled NO (FENO), 24-hour oesophageal pH monitoring and EBC collection with subsequent analysis of pH, carbon dioxide tension, oxygen tension, and concentrations of magnesium, calcium, iron and urates. ResultsNo significant differences were found for individual EBC biomarkers between asthmatics and non-asthmatics (p>0.05 for all). A pattern of six EBC biomarkers showed a statistically significant (p=0.046) predictive model for asthma (AUC=0.698, PPV=84.2%, NPV=38.9%). None to moderate association (R2 up to 0.43) between EBC biomarkers and lung function measures and FENO was found, with IOS parameters showing the best association with EBC biomarkers. A significantly higher EBC Fe was found in children with asthma and GERD compared to asthmatics without GERD (p=0.049). ConclusionsAn approach that involves a pattern of EBC biomarkers had a better diagnostic accuracy for asthma in children in real-life settings compared to a single one. Poor to moderate association of EBC biomarkers with lung function suggests a complementary value of EBC analysis for asthma diagnosis in children.

Receiver operating characteristics of impulse oscillometry parameters for predicting obstructive sleep apnea in preobese and obese snorers.

BackgroundInability to maintain upper-airway patency during sleep is a cause of obstructive sleep apnea (OSA) and its sequelae. The associated syndrome (OSAS) is common in obese populations, currently, nocturnal polysomnography is the gold standard for diagnosing this conditions, but the diagnostic procedures are expensive and time-consuming. Therefore, identification of new markers of OSAS would be useful. This study aims to examine the receiver operating characteristics of impulse oscillometry (IOS) parameters for the prediction of OSAS in preobese and obese snoring patients.MethodsIn total, 230 patients with normal spirometric values were included in this cross-sectional study. Full laboratory polysomnography was performed and IOS measurements were determined in sitting and supine positions to obtain respiratory impedance (Zrs), resistance (Rrs), and reactance (Xrs) parameters. The respiratory resistance at zero-frequency (Rrs0) was extrapolated by linear regression analysis of Rrs versus low-oscillatory-frequencies and its inverse, respiratory conductance (Grs), was calculated.ResultsIn both the sitting and supine positions Rrs0, Zrs, and Rrs at five oscillatory-frequencies (Hz) and Grs, the reciprocal of Zrs5 (Gz), and Xrs at 5 Hz all had significant positive or negative correlations with OSAS severity as defined by the Respiratory disturbance index (RDI). The correlation coefficients between Rrs0, Zrs5, Rrs5, Grs, Gz, Xrs5 measured in the supine and RDI were 0.425, 0.395, 0.378, −0.425, −0.395, and −0.517, respectively (all p < 0.001). The receiver operating characteristics curves showed that Xrs at 5 Hz (reactance) in the supine position was the best for predicting OSAS with a sensitivity of 73 % and specificity of 84 % at the optimal cut-off point of −0.23 (kPa s L−1). The other parameters also showed acceptable discriminating power. A logistic-regression model based on respiratory function abnormalities revealed that reactance combined with patient sex and lung volume yielded a specificity of 83.3 % with a sensitivity of 76.8 % for indicating OSAS.ConclusionRespiratory resistance and reactance measured by IOS are abnormal in preobese and obese OSAS patients, and these parameters are moderate to closely correlated with OSAS severity. IOS might be a useful screening tool for detecting OSAS in clinic based populations.