A Comparative Observational Study of the Diagnostic Utility of Impulse Oscillometry Versus Spirometry in Obstructive Airway Diseases.

Background Obstructive airway diseases, including asthma and chronic obstructive pulmonary disease (COPD), significantly impact respiratory function, making accurate diagnosis and differentiation essential for proper management. While spirometry is the gold standard for assessing lung function, impulse oscillometry (IOS) has emerged as a complementary tool, especially when spirometry results are inconclusive. This study aimed to compare the diagnostic utility of IOS with spirometry in patients with obstructive airway diseases and evaluate the correlation between these two methods. Methods A comparative observational study was conducted over 18 months at a tertiary care hospital in central India, including 130 patients (65 with asthma and 65 with COPD). Diagnostic evaluations using spirometry and IOS were performed before and after bronchodilator administration. Spirometry parameters assessed were forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio, while IOS parameters evaluated included resistance at 5 Hz (R5), resistance at 20 Hz (R20), resonant frequency (Fres), reactance at 5 Hz (X5), and the area under the reactance curve (AX). Statistical analysis was conducted using IBM SPSS version 27.0 (IBM Corp., Armonk, USA) and GraphPad Prism version 7.0 (Dotmatics, Boston, USA). Results Significant differences were observed in spirometry parameters between asthma and COPD groups, with asthma patients showing better lung function (FEV1, FVC, and FEV1/FVC; p<0.05). No significant differences were found in IOS parameters between the groups except for a correlation between FEV1 (%) and IOS measurements in the asthma group. Spirometry demonstrated superior sensitivity in identifying airway obstruction compared to IOS. However, IOS was more effective in detecting peripheral airway obstruction in asthma patients, with 22 out of 65 (33.85%) asthma patients showing peripheral airway obstruction compared to six out of 65 (9.23%) COPD patients (p=0.001). Conclusion While spirometry remains the primary diagnostic tool for assessing obstructive airway diseases, IOS is a valuable adjunct, particularly for detecting peripheral airway involvement in asthma patients. Combining spirometry and IOS enhances diagnostic accuracy and provides a more comprehensive assessment of lung function in patients with asthma and COPD.

Association between handgrip strength and small airway disease in patients with stable chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is associated with airflow limitation resulting from a combination of small airway disease (SAD) and parenchymal destruction. Although various diagnostic methods for SAD exist, access to these tools can be limited. OBJECTIVES: This study aimed to explore the correlation between handgrip strength (HGS) and SAD in COPD patients. DESIGN: Cross-sectional prospective study. METHODS: HGS was measured using a hand dynamometer. SAD was evaluated using impulse oscillometry, with results reported as the difference between respiratory resistance at 5 and 20 Hz (R5-R20). SAD was defined as R5-R20 ⩾0.07 kPa/L/s. The receiver operator characteristic (ROC) curves, sensitivity, and specificity values were calculated to determine the optimal cutoff value of HGS for predicting SAD. RESULTS: Sixty-four patients (90.6% male) were included. The average age was 72.1 ± 8.3 years, and body mass index was 23.4 ± 4.2 kg/m2. FEV1 was 71.6 ± 21.3%, and HGS was 30.2 ± 8.1 kg. R5-R20 was 0.11 ± 0.08 kPa/L/s. SAD was found in 64.1% of patients. A negative correlation between HGS and R5-R20 was observed (r = -0.332, p = 0.007). The best cutoff value for HGS in detecting SAD was determined to be 28.25 kg, with a sensitivity of 73.9%, specificity of 65.9%, and an area under ROC curve of 0.685 (95% CI 0.550-0.819, p = 0.015). CONCLUSION: SAD is common in COPD patients, and HGS is significantly negatively correlated with SAD. This tool might serve as an alternative or adjunctive assessment for small airway dysfunction in COPD patients. REGISTRATION: This study was registered with ClinicalTrials.gov with number NCT06223139.

Association of handgrip strength with small airway disease in COPDIn chronic obstructive pulmonary disease (COPD), the condition of small airways (those less than 2 mm wide) is closely linked to disease severity. Small airway disease (SAD) leads to reduced lung function, increased retention of excess gas in the lung, and poorer health in COPD patients. While various diagnostic methods exist for SAD, they may not always be accessible. This study investigated handgrip strength as a potential alternative way to assess SAD. Our findings show a significant negative correlation between handgrip strength and SAD in COPD patients. This suggests that handgrip strength could be used alongside existing methods to evaluate small airway dysfunction in these patients.

Clinical Value of Impulse Oscillometry in Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis.

INTRODUCTION: Impulse oscillometry (IOS) is an effortless test compared to spirometry. Numerous studies explored the role of IOS in spirometry-based chronic obstructive pulmonary disease (COPD), but most of them had limited sample sizes with poor statistical power. This systematic review and meta-analysis aimed to pool the individual data and quantitatively analyze the clinical value of IOS in COPD. METHODS: PubMed, Web of Science, Ovid, Cochrane Library, China National Knowledge Internet, and Wanfang were searched for studies with comparisons of IOS indicators between COPD patients and healthy controls, including respiratory resistance at 5 Hz (R5) and 20 Hz (R20), difference between R5 and R20 (R5-R20), respiratory reactance at 5 Hz (X5), resonant frequency (Fres), and area of reactance (Ax). Meta-analyses were conducted to calculate the weighted mean differences (WMDs) and 95% confidence intervals (CIs). RESULTS: 39 eligible studies were enrolled, involving 6,144 COPD patients and 4,611 healthy controls. Relative to healthy controls, COPD patients had significantly higher R5 (WMD: 0.17, 95% CI: 0.14, 0.20), R5-R20 (WMD: 0.13, 95% CI: 0.11, 0.15), Fres (WMD: 9.04, 95% CI: 7.66, 10.42), Ax (WMD: 1.24, 95% CI: 0.86, 1.61), and lower X5 (WMD: -0.15, 95% CI: -0.18, -0.11), and such differences became even greater as the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage escalated. Pooled correlation coefficients presented that R5, R5-R20, Fres, and X5 were significantly related to post-bronchodilator forced expiratory volume in the first second (FEV1)/forced vital capacity ratio (meta r = -0.37, -0.45, -0.53, and 0.42, respectively) and FEV1 as a percentage of predicted value (meta r = -0.43, -0.54, -0.59, and 0.56, respectively). CONCLUSION: IOS may be a supplement to spirometry in diagnosing and assessing COPD, especially when spirometry is inappropriate. More well-designed, large sample-sized, prospective studies are warranted to establish an IOS-based criterion for COPD management.

Impulse Oscillometry Combined to FeNO in Relation to Asthma Control Among Preschool Children.

Objective: We aimed to observe and analyze the differences in impulse oscillometry (IOS) and fractional expiratory nitric oxide (FeNO) in relation to asthma control among preschool children, and to explore the predictive value of IOS combined with FeNO for uncontrolled asthma. Methods: This study enrolled 171 preschool children with asthma and 30 healthy preschool children between June 2022 and June 2023. We categorized the asthmatic children as having controlled asthma (n=85) and uncontrolled asthma (n=86) after a 3-month follow-up. IOS and FeNO were collected on the first visit at baseline. Differences in metrics were compared between controlled asthma, uncontrolled asthma and healthy control groups. The area under the receiver operating characteristic curve (AUROC) was utilized to explore the discriminative ability of IOS and FeNO, alone or in combination, against uncontrolled asthma. Results: Compared to the controlled asthma group, the IOS values of R5, X5, R5-R20, and Fres were significantly higher in the uncontrolled asthma group, except for R20. R5 and R5-R20 had the highest area under the curve (AUC), which could reach 0.74 (95% CI 0.66-0.82) and 0.72 (95% CI 0.64-0.80). R20 had the lowest AUC of 0.59. The AUC for FeNO alone was 0.88 (95% CI 0.84-0.93) with a cutoff value of 17.50 ppb, sensitivity and specificity of 0.73 and 0.89. The AUCs of all IOS metrics combined with FeNO were significantly higher, with the highest AUC of 0.92 (95% CI 0.87-0.96) for R5-R20+FeNO, and with a sensitivity and specificity of 0.88 and 0.84. Conclusion: There were significant differences in IOS and FeNO in relation to asthma control among preschooler children. FeNO might be the best predictor of asthma control, and adding any of IOS metrics increased moderately the predictive value.

Therapeutic effect of long-acting muscarinic antagonist for treating uncontrolled asthma assessed using impulse oscillometry.

BACKGROUND: In recent years, the incorporation of LAMAs into asthma therapy has been expected to enhance symptom control. However, a significant number of patients with asthma continue to experience poorly managed symptoms. There have been limited investigations on LAMA-induced airway alterations in asthma treatment employing IOS. In this study, we administered a LAMA to patients with poorly controlled asthma, evaluated clinical responses and respiratory function, and investigated airway changes facilitated by LAMA treatments using the IOS. METHODS: Of a total of 1282 consecutive patients with asthma, 118 exhibited uncontrolled symptoms. Among them, 42 switched their treatment to high-dose fluticasone furoate/umeclidinium/vilanterol (FF/UMEC/VI) (ICS/LABA/LAMA). The patients were then assessed using AHQ-33 or LCQ and ACT. Spirometry parameters (such as FEV1 or MMEF) and IOS parameters (such as R20 or AX) were measured and compared before and after exacerbations and the addition of LAMA. RESULTS: Of the 42 patients, 17 who switched to FF/UMEC/VI caused by dyspnea exhibited decreased pulmonary function between period 1 and baseline, followed by an increase in pulmonary function between baseline and period 2. Significant differences were observed in IOS parameters such as R20, R5-R20, Fres, or AX between period 1 and baseline as well as between baseline and period 2. Among the patients who switched to inhaler due to cough, 25 were classified as responders (n = 17) and nonresponders (n = 8) based on treatment outcomes. Among nonresponders, there were no significant differences in spirometry parameters such as FEV1 or PEF and IOS parameters such as R20 or AX between period 1 and baseline. However, among responders, significant differences were observed in all IOS parameters, though not in most spirometry parameters, between period 1 and baseline. Furthermore, significant differences were noted between baseline and period 2 in terms of FEV1, %MMEF, %PEF, and all IOS parameters. CONCLUSION: ICS/LABA/LAMA demonstrates superiority over ICS/LABA in improving symptoms and lung function, which is primarily attributed to the addition of LAMA. Additionally, IOS revealed the effectiveness of LAMA across all airway segments, particularly in the periphery. Hence, LAMA can be effective against various asthma phenotypes characterized by airway inflammation, even in real-world cases.

Small airway dysfunction measured by impulse oscillometry is associated with exacerbations and poor symptom control in patients with asthma treated in a tertiary hospital subspecialist airways disease clinic.

Introduction: Small airways dysfunction contributes to asthma pathophysiology and clinical outcomes including exacerbations and asthma control. Respiratory oscillometry is a simple, non-invasive and effort independent lung function test that provides vital information about small airway function. However, interpretation and clinical utility of respiratory oscillometry has been in part limited by lack of agreed parameters and the respective cutoffs. The aim of this study was to determine the prevalence of small airways dysfunction based on published impulse oscillometry (IOS) definition in patients with asthma referred to a tertiary asthma clinic and the extent to which it correlates with asthma clinical outcomes. Methods: We retrospectively reviewed the medical records of all patients with asthma managed in the severe asthma clinic between January 2019 and December 2022 who underwent routine lung function tests with oscillometry and spirometry. Small airways dysfunction was determined from various published IOS parameter cutoffs, and the data were analysed to determine correlations between IOS parameters and asthma outcomes. Results: Amongst the 148 patients, the prevalence of small airways dysfunction ranged from 53% to 78% depending on the defining oscillometry parameter. All oscillometry parameters correlated with the severity of airflow obstruction (FEV1% predicted, p < 0.001). Several oscillometry parameters correlated with asthma symptom burden, the strongest correlation was seen for frequency dependent resistance (R5-R20) with scores of Asthma Control Questionnaire (ACQ6) (Spearman's rank coefficient 0.213, p = 0.028) and Asthma Control Test (ACT) (Spearman's rank coefficient -0.248, p = 0.012). R5-R20 was predictive of poor asthma control defined by ACQ6 >1.5 (OR 2.97, p = 0.022) or ACT <20 (OR 2.44, p = 0.055). Small airways dysfunction defined by R5-R20 and area under the reactance curve (AX) also significantly increases asthma exacerbation risk (OR 2.60, p = 0.02 and OR 2.31, p = 0.03 respectively). Conclusion: Respiratory oscillometry is a sensitive measure of small airways dysfunction that should complement spirometry in the routine assessment of asthma. Small airways dysfunction is highly prevalent in patients with asthma referred to a tertiary asthma clinic. R5-R20 was the metric most predictive in identifying patients at risk of asthma exacerbations and poor asthma control.

Performance of Impulse Oscillometry in Identifying Restrictive Lung Defects in a Veteran Cohort.

Background: Impulse oscillometry (IOs) is a technique used to evaluate lung function that uses sound waves imposed over tidal breathing to characterize the airways and lung parenchyma. IOs has been particularly useful in the identification of obstructive lung defects. The present analysis seeks to explore the use of IOs in the identification of restrictive lung physiology among a group of Gulf War I veterans exposed to depleted uranium (DU). Methods: A total of 36 out of a dynamic 85-veteran cohort attended in-person surveillance visits in 2019 and completed both IOs and PFTs. Performance on IOs was evaluated in a cross-sectional analysis of the group overall and in those identified as having restrictive lung defects defined by either spirometry (FEV1/FVC ≥ LLN and FVC < LLN) or lung volumes (TLC < LLN). Results: A total of 6 individuals were identified as having restriction (4 based on spirometry alone and an additional 2 by lung volumes). When restriction was present, IOs values of both resistance and reactance were significantly more abnormal. Conclusion: In the assessment of lung function, IOs may be advantageous over PFTs because it is faster to perform and effort-independent. Although little is known about the utility of IOs in identifying restrictive lung physiology, our results support its use.

Machine learning for accurate detection of small airway dysfunction-related respiratory changes: an observational study.

BACKGROUND: The use of machine learning(ML) methods would improve the diagnosis of small airway dysfunction(SAD) in subjects with chronic respiratory symptoms and preserved pulmonary function(PPF). This paper evaluated the performance of several ML algorithms associated with the impulse oscillometry(IOS) analysis to aid in the diagnostic of respiratory changes in SAD. We also find out the best configuration for this task. METHODS: IOS and spirometry were measured in 280 subjects, including a healthy control group (n = 78), a group with normal spirometry (n = 158) and a group with abnormal spirometry (n = 44). Various supervised machine learning (ML) algorithms and feature selection strategies were examined, such as Support Vector Machines (SVM), Random Forests (RF), Adaptive Boosting (ADABOOST), Navie Bayesian (BAYES), and K-Nearest Neighbors (KNN). RESULTS: The first experiment of this study demonstrated that the best oscillometric parameter (BOP) was R5, with an AUC value of 0.642, when comparing a healthy control group(CG) with patients in the group without lung volume-defined SAD(PPFN). The AUC value of BOP in the control group was 0.769 compared with patients with spirometry defined SAD(PPFA) in the PPF population. In the second experiment, the ML technique was used. In CGvsPPFN, RF and ADABOOST had the best diagnostic results (AUC = 0.914, 0.915), with significantly higher accuracy compared to BOP (p < 0.01). In CGvsPPFA, RF and ADABOOST had the best diagnostic results (AUC = 0.951, 0.971) and significantly higher diagnostic accuracy (p < 0.01). In the third, fourth and fifth experiments, different feature selection techniques allowed us to find the best IOS parameters (R5, (R5-R20)/R5 and Fres). The results demonstrate that the performance of ADABOOST remained essentially unaltered following the application of the feature selector, whereas the diagnostic accuracy of the remaining four classifiers (RF, SVM, BAYES, and KNN) is marginally enhanced. CONCLUSIONS: IOS combined with ML algorithms provide a new method for diagnosing SAD in subjects with chronic respiratory symptoms and PPF. The present study's findings provide evidence that this combination may help in the early diagnosis of respiratory changes in these patients.

Is there a correlation between the changes in airway inflammation and the changes in respiratory mechanics after vaping in patients with asthma?

BACKGROUND: Electronic cigarettes (ECs) have been promoted as alternatives to traditional cigarettes. AIM: To investigate ECs' effects on respiratory system, especially in patients with respiratory diseases. METHODS: We randomly selected 25 smokers with stable moderate asthma and matched them with 25 healthy smokers. All were subjucted to pulmonary function tests (PFTs), impulse oscillometry (IOS), fraction exhaled Nitric Oxide (FeNO), exhaled breathe condensate (EBC) and biomarker measurements before and after vaping one nicotine-containing EC. RESULTS: The increase in FeNO 30 minutes after EC, reflecting airway inflammation, significantly correlated with increase of residual volume (RV), total lung capacity, respiratory impedance at 5 Hz (Z5Hz) and respiratory resistance at 5 and 20 Hz (R5Hz and R20Hz). No significant correlations were found between EBC biomarkers' changes and respiratory mechanics. CONCLUSION: This is the first study demonstrating that the changes in airway inflammation caused by EC have direct effects in respiratory mechanics of asthmatic patients.

Advances in Pediatric Lung Function Testing Techniques.

For decades spirometry has been the benchmark test for capturing lung function in children but its recognized limitations required the development of other techniques. This article introduces novel techniques in lung function assessment for pediatric patients, including multiple breath washout, impulse oscillometry, structured light plethysmography, and electrical impedance tomography, and common themes in interpreting the results. Challenges include standardization, reference data, and clinical integration of these innovative tools. Further research is ongoing to optimize these tests for clinical use, especially in diverse populations and pediatric settings.

Small airway resistance in obese and nonobese patients with obstructive sleep apnea syndrome using impulse oscillometry.

Background/aim: There is limited information on the pathologic changes in the small airways among obese and nonobese patients with obstructive sleep apnea syndrome (OSAS). Impulse oscillometry (IOS) measures airway resistance and reactance independently of patient effort. This study aimed to compare airway resistance in small airways using IOS between obese and nonobese patients with OSAS. Materials and methods: In this real-life cross-sectional study, demographic information was collected from obese and nonobese subjects diagnosed with moderate and severe OSAS without any other underlying diseases. Spirometry and IOS measurements were conducted, and the values of both groups were statistically analyzed. Results: The nonobese group had a mean age of 45.6 ± 11.7 years (median 45), while the obese group had a mean age of 48.4 ± 9.5 years (median 47.5). The mean body mass index (BMI) for the nonobese group was 26.2 ± 2.1 kg/m2 (median 27 kg/m2), and for the obese group, it was 35.6 ± 6.4 kg/m2 (median 33 kg/m2). Statistically significant differences were observed between the two groups in R5 - R20 percentage, reactance area (AX), and resonant frequency (Fres) values (p < 0.05). Conclusion: Among obese OSAS patients, there is an increase in resistance in small airways as indicated by IOS values. IOS shows promise as a potential screening tool for diagnosing OSAS.

Impulse oscillometry in patients with persistent post-COVID-19 symptoms: A retrospective study.

Introduction: Impaired lung function has been observed in patients following COVID-19 infection, with studies reporting persistent lung volume and diffusing capacity impairments. Some studies have demonstrated significantly higher small airway resistance in COVID-19 positive cases. This retrospective study aims to examine impulse oscillometry (IOS) data of patients with persistent symptoms after COVID-19 infection, focusing on the relationship between time and symptoms. Material and Method: The study analyzed data from adult patients with persistent symptoms who underwent IOS testing within and after 84 days from the diagnosis date. Result: The results showed that patients within 84 days and those between 31 and 84 days had higher small airway resistance values, indicating peripheral airway disease. Patients with dyspnea exhibited higher IOS values compared to those with cough symptoms, suggesting more significant impairment in the peripheral airways. Conclusion: The study highlights the importance of using comprehensive diagnostic tools like IOS to assess respiratory impairments in post-COVID-19 patients, particularly in the small airways. Understanding the relationship between time and symptoms can provide valuable insights for the treatment of peripheral airway dysfunction in post-COVID-19 patients.

Impulse oscillometry in the diagnosis of cough variant asthma in children.

BACKGROUND: Cough variant asthma (CVA) is one of the most common causes of chronic cough in children worldwide. The diagnosis of CVA in children remains challenging. This study aimed to assess the diagnostic utility of impulse oscillometry (IOS) pulmonary function in children with CVA. METHODS: This study included children aged 4 to 12 years diagnosed with CVA who underwent IOS pulmonary function and bronchodilation (BD) tests. A control group of healthy children was matched. Pre- and post-BD IOS parameters were recorded and presented as mean ± standard deviation or median. Receiver operating characteristic (ROC) curves were plotted, and the area under the curve (AUC) was calculated to evaluate the discriminatory potential of the IOS parameters for diagnosing CVA. RESULTS: A total of 180 patients with CVA and 65 control subjects were included. The baseline IOS parameters in the CVA group, except X5%pred, were significantly greater compared to the control group. After inhalation of salbutamol sulfate, all IOS parameters improved significantly in the CVA group. However, Z5%pred, R5%pred, and R20%pred remained greater in the CVA group compared to the control group. The improvement rates of IOS parameters in the CVA group significantly surpassed those in the control group. The ROC curve results for pre-BD IOS parameters and the improvement rate during the BD test showed that the combinations of pre-Z5%pred+△Z5% and pre-R5%pred+△R5% achieved the highest AUC value of 0.920 and 0.898, respectively. The AUC values of these combined parameters surpassed those of individual ones. CONCLUSIONS: This study highlights that children with CVA exhibit greater IOS parameters compared to healthy children. The changes in IOS parameters during the BD test provided valuable diagnostic information for CVA, and the combination of various parameters can help pediatricians accurately identify CVA in children.

Usefulness of Impulse Oscillometry in Predicting the Severity of Bronchiectasis.

BACKGROUND: Bronchiectasis is a chronic respiratory disease that leads to airway inflammation, destruction, and airflow limitation, which reflects its severity. Impulse oscillometry (IOS) is a non-invasive method that uses sound waves to estimate lung function and airway resistance. The aim of this study was to assess the usefulness of IOS in predicting the severity of bronchiectasis. METHODS: We retrospectively reviewed the IOS parameters and clinical characteristics in 145 patients diagnosed with bronchiectasis between March 2020 and May 2021. Disease severity was evaluated using the FACED score, and patients were divided into mild and moderate/severe groups. RESULTS: Forty-four patients (30.3%) were in the moderate/severe group, and 101 (69.7%) were in the mild group. Patients with moderate/severe bronchiectasis had a higher airway resistance at 5 Hz (R5), a higher difference between the resistance at 5 and 20 Hz (R5-R20), a higher resonant frequency (Fres), and a higher area of reactance (AX) than patients with mild bronchiectasis. R5 ≥0.43, resistance at 20 Hz (R20) ≥0.234, R5-R20 ≥28.3, AX ≥1.02, reactance at 5 Hz (X5) ≤-0.238, and Fres ≥20.88 revealed significant univariable relationships with bronchiectasis severity (p<0.05). Among these, only X5 ≤-0.238 exhibited a significant multivariable relationship with bronchiectasis severity (p=0.039). The receiver operating characteristic curve for predicting moderate- to-severe bronchiectasis of FACED score based on IOS parameters exhibited an area under the curve of 0.809. CONCLUSION: The IOS assessed by the disease severity of FACED score can effectively reflect airway resistance and elasticity in bronchiectasis patients and serve as valuable tools for predicting bronchiectasis severity.

Predictive Value of Impulse Oscillometry Combined with Fractional Expiratory Nitric Oxide Test for Asthma in Preschool Children.

Objective: Prediction of asthma in preschool children is challenging and lacks objective indicators. The aim is to observe and analyze the variances between impulse oscillometry (IOS) and fractional expiratory nitric oxide (FeNO) in preschool children with wheezing, establish a joint prediction model, and explore the diagnostic value of combining IOS with FeNO in diagnosing asthma among preschool children. Patients and methods: This study enrolled children aged 3-6 years with wheezing between June 2021 and June 2022. They were categorized as asthmatic (n=104) or non-asthmatic (n=109) after a 1-year follow-up. Clinical data, along with IOS and FeNO measurements from both groups, underwent univariate regression and multiple regression analyses to identify predictive factors and develop the most accurate model. The prediction model was built using the stepwise (stepAIC) method. The receiver operating characteristic curve (ROC), calibration curve, Hosmer-Lemeshow test, and decision curve analysis (DCA) were employed to validate and assess the model. Results: During univariate analysis, a history of allergic rhinitis, a history of eczema or atopic dermatitis, and measures including FeNO, R5, X5, R20, Fres, and R5-R20 were found to be associated with asthma diagnosis. Subsequent multivariate analysis revealed elevated FeNO, R5, and X5 as independent risk factors. The stepAIC method selected five factors (history of allergic rhinitis, history of eczema or atopic dermatitis, FeNO, R5, X5) and established a prediction model. The combined model achieved an AUROC of 0.94, with a sensitivity of 0.89 and specificity of 0.88, surpassing that of individual factors. Calibration plots and the HL test confirmed satisfactory accuracy. Conclusion: This study has developed a prediction model based on five factors, potentially aiding clinicians in early identification of asthma risk among preschool children.

Relationships between lung function, allergy, and wheezing in urban children.

BACKGROUND: Allergic sensitization and low lung function in early childhood are risk factors for subsequent wheezing and asthma. However, it is unclear how allergic sensitization affects lung function over time. OBJECTIVE: We sought to test whether allergy influences lung function and whether these factors synergistically increase the risk of continued wheezing in childhood. METHODS: We analyzed longitudinal measurements of lung function (spirometry and impulse oscillometry) and allergic sensitization (aeroallergen skin tests and serum allergen-specific IgE) throughout early childhood in the Urban Environmental and Childhood Asthma study, which included high-risk urban children living in disadvantaged neighborhoods. Intraclass correlation coefficients were calculated to assess lung function stability. Cluster analysis identified low, medium, and high allergy trajectories, which were compared with lung function and wheezing episodes in linear regression models. A variable selection model assessed predictors at age 5 years for continued wheezing through age 12 years. RESULTS: Lung function adjusted for growth was stable (intraclass correlation coefficient, 0.5-0.7) from age 5 to 12 years and unrelated to allergy trajectory. Lung function and allergic sensitization were associated with wheezing episodes in an additive fashion. In children with asthma, measuring lung function at age 5 years added little to the medical history for predicting future wheezing episodes through age 12 years. CONCLUSIONS: In high-risk urban children, age-related trajectories of allergic sensitization were not associated with lung function development; however, both indicators were related to continued wheezing. These results underscore the importance of understanding early-life factors that negatively affect lung development and suggest that treating allergic sensitization may not alter lung function development in early to mid-childhood.

Using Machine Learning with Impulse Oscillometry Data to Develop a Predictive Model for Chronic Obstructive Pulmonary Disease and Asthma.

We aimed to develop and validate a machine learning model using impulse oscillometry system (IOS) profiles for accurately classifying patients into three assessment-based categories: no airflow obstruction, asthma, and chronic obstructive pulmonary disease (COPD). Our research questions were as follows: (1) Can machine learning methods accurately classify obstructive disease states based solely on multidimensional IOS data? (2) Which IOS parameters and modeling algorithms provide the best discrimination? We used data for 480 patients (240 with COPD and 240 with asthma) and 84 healthy individuals for training. Physiological and IOS parameters were combined into six feature combinations. The classification algorithms tested were logistic regression, random forest, neural network, k-nearest neighbor, and support vector machine. The optimal feature combination for identifying individuals without pulmonary obstruction, with asthma, or with COPD included 15 IOS and physiological features. The neural network classifier achieved the highest accuracy (0.786). For discriminating between healthy and unhealthy individuals, two combinations of twenty-three features performed best in the neural network algorithm (accuracy of 0.929). When distinguishing COPD from asthma, the best combination included 15 features and the neural network algorithm achieved an accuracy of 0.854. This study provides compelling technical evidence and clinical justifications for advancing IOS data-driven models to aid in COPD and asthma management.

Clinical characterization and outcomes of impulse oscillometry-defined bronchodilator response: an ECOPD cohort-based study.

BACKGROUND: The clinical significance of the impulse oscillometry-defined small airway bronchodilator response (IOS-BDR) is not well-known. Accordingly, this study investigated the clinical characteristics of IOS-BDR and explored the association between lung function decline, acute respiratory exacerbations, and IOS-BDR. METHODS: Participants were recruited from an Early Chronic Obstructive Pulmonary Disease (ECOPD) cohort subset and were followed up for two years with visits at baseline, 12 months, and 24 months. Chronic obstructive pulmonary disease (COPD) was defined as a post-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio < 0.70. IOS-BDR was defined as meeting any one of the following criteria: an absolute change in respiratory system resistance at 5 Hz ≤ - 0.137 kPa/L/s, an absolute change in respiratory system reactance at 5 Hz ≥ 0.055 kPa/L/s, or an absolute change in reactance area ≤ - 0.390 kPa/L. The association between IOS-BDR and a decline in lung function was explored with linear mixed-effects model. The association between IOS-BDR and the risk of acute respiratory exacerbations at the two-year follow-up was analyzed with the logistic regression model. RESULTS: This study involved 466 participants (92 participants with IOS-BDR and 374 participants without IOS-BDR). Participants with IOS-BDR had higher COPD assessment test and modified Medical Research Council dyspnea scale scores, more severe emphysema, air trapping, and rapid decline in FVC than those without IOS-BDR over 2-year follow-up. IOS-BDR was not associated with the risk of acute respiratory exacerbations at the 2-year follow-up. CONCLUSIONS: The participants with IOS-BDR had more respiratory symptoms, radiographic structural changes, and had an increase in decline in lung function than those without IOS-BDR. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900024643. Registered on 19 July, 2019.

Lower Arginine Bioavailability, Increased FeNO Levels, and Airway Resistance on Impulse Oscillometry Are Characteristics of Asthma in Children and Young Adults with Sickle Cell Disease.

Background and Objectives: Data on characteristics of asthma in children with sickle cell disease (SCD) is conflicting. Recently, the L-arginine pathway has gained attention in the pathogenesis of asthma and SCD. This study aimed to determine the distinctive clinical and laboratory features and the role of arginine metabolism in asthmatic children with SCD. Materials and Methods: A total of 52 children and adolescents with SCD, including 24 with asthma (SCD-A) and 28 without asthma (SCD-NA), and 40 healthy controls were included. A questionnaire, atopy tests, fractional exhaled nitric oxide (FeNO), and lung function tests were employed. Serum metabolites of the arginine pathway were measured. The results of the three groups were compared. Results: The demographic characteristics and atopy markers of the three groups were similar. FEV1%, FEV1/FVC, MMEF%, and total lung capacity (TLC%) values of SCD-A patients were not significantly different from the SCD-NA group, but they were significantly lower than the values measured in the controls. FeNO values greater than 35 ppb were present only in the SCD-A group. In impulse oscillometry, median resistance values at 5 Hz (R5)% were higher in both SCD subgroups than in healthy controls (p = 0.001). The (R5-20/R5)% values were higher in the SCD-A group (p = 0.028). Serum arginine levels and arginine bioavailability indices were significantly lower in the SCD-A group than in the SCD-NA group and healthy controls (p = 0.003 and p < 0.001). Conclusions: Asthma in children with SCD was not associated with atopy or low FEV1/FVC levels. However, lower arginine bioavailability and higher FeNO levels differentiated asthma in patients with SCD. High R5% and (R5-20/R5)% values indicated increased airway resistance in SCD, with a predominance of small airway disease in asthmatics.