Impulse Oscillometry Parameters Research Articles

Impulse oscillometry in the diagnosis of cough variant asthma in children

BackgroundCough 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.MethodsThis 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.ResultsA 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.ConclusionsThis 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.

: 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. : 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. : 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. : 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.

Role of impulse oscillometry together with diffusing capacity of the lungs for carbon monoxide and high-resolution computed tomography for the chest in early diagnosis of interstitial lung disease in patients with connective tissue diseases

Abstract Background Connective tissue diseases (CTDs) are systemic autoimmune disorders characterized by repeated lung involvement. Interstitial lung disease (ILD) can arise from nearly any CTD, imposing a significant burden on patients and strongly affecting their prognosis. Addressing the gaps in early diagnosis, monitoring, and treatment of these patients requires a comprehensive and multidisciplinary approach for optimal management. Aim To find the best modality for early diagnosis of ILD in patients with connective tissue disorders through the use of diffusing capacity of the lungs for carbon monoxide (DLCO), impulse oscillometry (IOS) and high-resolution computed tomography (HRCT) chest. Patients and methods This study was cross-sectional, analytical, and observational was conducted on 60 patients who were diagnosed with CTD, during the period from March 2022 to March 2023, who were admitted to Chest and Rheumatology Department or outpatient clinics visitors, to Ain Shams University Hospitals. Results The sensitivity of DLCO, HRCT, and IOS in detecting interstitial affection in CTD patients was 90, 81.5, and 72.2%, respectively. There is high statistical significance between DLCO and both CT chest and IOS in detecting ILD in CTD patients. There is a highly significant correlation between DLCO with Spirometric parameters (forced vital capacity, forced expiratory volume 1 s) and between DLCO with IOS parameters (actual ×5). Conclusion ILD should always be considered in patients with CTD. Diagnosis of CTD-ILD is challenging so early diagnosis of ILD using DLCO, HRCT chest or by using IOS is important as it could affect therapy plans.

Indices of airway resistance and reactance from impulse oscillometry correlate with aerosol particle emission in different age groups

Airborne transmission of pathogens plays a major role in the spread of infectious diseases. Aerosol particle production from the lung is thought to occur in the peripheral airways. In the present study we investigated eighty lung-healthy subjects of two age groups (20–39, 60–76 years) at rest and during exercise whether lung function parameters indicative of peripheral airway function were correlated with individual differences in aerosol particle emission. Lung function comprised spirometry and impulse oscillometry during quiet breathing and an expiratory vital capacity manoeuvre, using resistance (R5) and reactance at 5 Hz (X5) as indicators potentially related to peripheral airway function. The association between emission at different ventilation rates relative to maximum ventilation and lung function was assessed by regression analysis. In multiple regression analyses including age group, only vital capacity manoeuvre R5 at 15% to 50% of end-expiratory vital capacity as well as quiet breathing X5 were independently linked to particle emission at 20% to 50% of maximum ventilation, in addition to age group. The fact that age as predictive factor was still significant, although to a lower degree, points towards further effects of age, potentially involving surface properties not accounted for by impulse oscillometry parameters.

Impulse Oscillometry as an Alternative Lung Function Test for Hospitalized Adults.

Impulse oscillometry (IOS) is a noninvasive technique that measures lung physiology independently of patient effort. In the present study, we aimed to investigate the utility of IOS parameters in comparison with pulmonary function testing (PFT) among hospitalized subjects, with emphasis on obstructive and small airway diseases. Sixty-one subjects hospitalized either with unexplained dyspnea or for pre-surgery evaluation were included in the study. All subjects underwent PFTs and IOS test. The correlation between IOS results and PFTs was examined in different subgroups. The ability of IOS parameters to predict abnormal PFTs was evaluated using the area under the receiver operating characteristic (ROC) curve, and optimal cutoff values were calculated. IOS results were found to correlate with PFT values. Subgroup analysis revealed that these correlations were higher in younger (age < 70) and non-obese (body mass index < 25kg/m2) subjects. The resonant frequency was an independent predictor and had the best predictive ability for abnormal FEV1/FVC (area under the ROC curve 0.732 [95% CI 0.57-0.90], optimal cutoff 17 Hz, 87% sensitivity, 62% specificity) and abnormal forced expiratory flow during the middle half of the FVC maneuver (area under the ROC curve 0.667 [95% CI 0.53-0.81], optimal cutoff 15 Hz, 77% sensitivity, 54% specificity). Area of reactance and the difference in respiratory resistance at 5 Hz and 20 Hz also showed a good predictive ability for abnormal FEV1/FVC (area under the ROC curve 0.716 and 0.730, respectively). We found that the IOS performed well in diagnosing small airway and obstructive diseases among hospitalized subjects. IOS might serve as an alternative to standard PFTs in non-cooperative or dyspneic hospitalized patients.

The possibilities of impulse oscillometry in the diagnosis of the lung function disorders after COVID-19

Impulse oscillometry (IOS) is an effort independent method of studying lung mechanics. To study the diagnostic significance of IOS in assessing lung mechanics after COVID-19. Spirometry, body plethysmography, diffusion test (DLco), IOS parameters were analyzed in 315 patients (the median age 48 years), the median period from the beginning of COVID-19 to the study was 50 days. Statistical analysis included descriptive statistics, correlation analysis and one-dimensional logistic regression analysis with an assessment of odds ratios. In general group, spirometry and body plethysmography parameters were in normal values, while DLCO was reduced in 61% of patients. Parameters of IOS were analyzed in the general group and between the groups, depending on the value of DLco and total lung capacity (TLC): normal or reduced. In general group, reactance area (AX), hererogeneity of resistance Rrs5-Rrs20, resistance at 5 Hz (Rrs5), reactance at 5 Hz (ΔXrs5) were increased in 29.8%, 17.8%, 6%, 4.8% of patients, respectively, and were statistically significantly higher in the group with reduced TLC, whereas in the group with reduced DLco AX, Rrs5-Rrs20 were statistically significantly higher. Logistic regression analysis showed that patients with Rrs5-Rrs20>0.07 kPa×sec/l or AX>0.32 kPa/l had a 1.99-fold and 2.24-fold increased risk for decrease DLco, respectively, while the risk of decrease in TLC was 2.25-fold (p=0.012) and 3.16-fold (p<0.001) higher, respectively. IOS allow to detect both dysfunction of small airways (if AX or Rrs5-Rrs20 are increased) and the risk of restrictive pattern and lung diffusion impairment after COVID-19.

Impulse Oscillometry Versus Spirometry to Detect Bronchiolitis Obliterans Syndrome in Bilateral Lung Transplant Recipients: A Prospective Diagnostic Study.

Chronic lung allograft dysfunction (CLAD), and especially bronchiolitis obliterans syndrome (BOS), remain dominant causes of morbidity and mortality after lung transplantation. Interest is growing in the forced oscillation technique, of which impulse oscillometry (IOS) is a form, as a tool to improve our understanding of these disorders. However, data remain limited and no longitudinal studies have been published, meaning there is no information regarding any capacity IOS may have for the early detection of CLAD. We conducted a prospective longitudinal study enrolling a consecutive sample of adult bilateral lung transplant recipients with healthy lung allografts or CLAD and performed ongoing paired IOS and spirometry tests on a clinically determined basis. We assessed for correlations between IOS and spirometry and examined any predictive value either modality may hold for the early detection of BOS. We enrolled 91 patients and conducted testing for 43 mo, collecting 558 analyzable paired IOS and spirometry tests, with a median of 9 tests per subject (interquartile range, 5-12) and a median testing interval of 92 d (interquartile range, 62-161). Statistically significant moderate-to-strong correlations were demonstrated between all IOS parameters and spirometry, except resistance at 20 Hz, which is a proximal airway measure. No predictive value for the early detection of BOS was found for IOS or spirometry. This study presents the first longitudinal data from IOS after lung transplantation and adds considerably to the growing literature, showing unequivocal correlations with spirometry but failing to demonstrate a predictive value for BOS.

Efficacy of Bhramari pranayama and Om chanting on asthma control, quality of life, and airway inflammation in asthmatic children: an open-label randomized controlled trial

Objectives To explore the efficacy of combination of Bhramari pranayama and om chanting as an adjunct to standard pharmacological treatment on asthma control, quality of life, pulmonary function, and airway inflammation in asthmatic children. Methods Children (n = 110; 8–15 years) with uncontrolled or partly controlled asthma were recruited from the Pediatric Chest Clinic of All India Institute of Medical Sciences, New Delhi. Eligible participants were randomized to either home-based online Bhramari pranayama and om chanting plus standard treatment (YI + ST) group, or standard treatment (ST) alone group. Primary outcome measures were 12-week change in level of asthma symptom control; asthma control questionnaire (ACQ) score, spirometry indices, impulse oscillometry parameters, and pediatric asthma quality of life questionnaire (PAQLQ) score. Secondary outcome was a change in fractional exhaled nitric oxide (FeNO) levels at 12 weeks. Beginning from the enrollment, every participant was evaluated at 0, 2, 6, and 12 weeks. Results After 12 weeks of intervention, higher proportion (68.2%) of children were found to have controlled asthma symptoms in the YI + ST group as compared to ST group (38.5%) according to per protocol analysis (p = 0.03). When compared to ST group, children in YI + ST group showed significantly lower ACQ score, higher PAQLQ score and reduced FeNO levels. No significant changes were observed for the lung function parameters. Conclusion Children practicing Bhramari pranayama and om chanting for 12 weeks have better asthma symptom control, quality of life, and reduced airway inflammation than those taking standard pharmacotherapy alone.

Application of impulse oscillometry to detect interstitial lung disease and airway disease in adults with rheumatoid arthritis

BackgroundWe conducted a retrospective observational study to explore the potential application of impulse oscillometry (IOS) as an alternative to high-resolution computed tomography (HRCT) for detecting pulmonary involvement in patients with rheumatoid arthritis (RA) because clinically evident interstitial lung disease (ILD) and airway involvement are common in this population.MethodsWe enrolled 72 patients with RA who underwent pulmonary function tests (PFTs) and IOS between September 2021 and September 2022. We aimed to identify the PFT and IOS variables associated with lung diseases shown on HRCT images.ResultsIn our cohort of 72 patients, 48 underwent HRCT; of these, 35 had airway disease or ILD and 13 showed no obvious abnormalities on HRCT. Abnormal IOS and PFT parameters were observed in 34 and 23 patients, respectively, with abnormal HRCT images. The predicted percentages for forced vital capacity, the ratio of forced expiratory volume in the first one second to forced vital capacity, and forced mid-expiratory flow value were significantly lower in patients with abnormal HRCT. Lung resistance at 5 Hz, difference in resistance between 5 and 20 Hz, resonant frequency (Fres), and reactance area were higher in these patients and reactance at 5 Hz was lower. Compared to other parameters, Fres > 14.14 was significantly associated with alterations in HRCT and may be used as an indicator for monitoring disease.ConclusionFres > 14.14 is significantly associated with lung involvement in RA patients. Performance of spirometry with IOS is more beneficial than spirometry alone for evaluating lung involvement in RA patients.

Correlation between impulse oscillometry parameters and test for respiratory and asthma control in kids (TRACK) in asthma control of preschoolers with asthma

Little research has been conducted to evaluate the correlation between impulse oscillometry (IOS), Childhood Asthma Control Test (C-ACT), and Test for Respiratory and Asthma Control in Kids (TRACK). This study was conducted at China Medical University Hospital between September 1, 2019, and March 31, 2021. Children aged 2-6 years who had been diagnosed with asthma with acute exacerbation were enrolled and followed-up until the end of the study. Correlations between the parameters of IOS, C-ACT and TRACK were assessed. The validity and reliability of TRACK were verified. A total of 114 children with asthma and acute exacerbations were recruited. Their mean age was 4.1±1.1 years, and 60.5% were males. After a year of treatment, the change of R5-R20 from baseline 0.64±0.38kPa/L/s to 12th month 0.48±0.2kPa/L/s (p=0.022). TRACK and C-ACT scores were significantly correlated during the observation period. R5-R20 in IOS at baseline and at the 12th month of follow-up as well as the change in IOS parameters were significantly associated with C-ACT (p=0.003, 0.015, and 0.001, respectively). R5% and R5-R20 changes in IOS were associated with TRACK (p=0.04 and 0.025, respectively). Sensitivity and specificity of TRACK were 80.8% (67.5-90.4) and 100% (94.1-100), respectively, with cut-off points >95 and AUC 93.8%. TRACK score appears to have a stronger association with the IOS parameter than C-ACT score. Our findings indicate that TRACK is a valid tool for assessing asthma control in preschool children.

Assessing Asthma Control by Impulse Oscillometry and Fractional Expiratory Nitric Oxide in Children With Normal Spirometry.

Because spirometric parameters fail to address current status of asthma in some patients, additional tests are required for better evaluation of asthma. We aimed to test the ability of impulse oscillometry (IOS) and fractional expiratory nitric oxide (FeNO) in identifying inadequately controlled asthma (ICA) that was not uncovered by spirometry. Recruited asthmatic children between ages of 8 and 16 years underwent spirometry, IOS, and FeNO measurements on the same day. Only subjects who had spirometric indices within normal range were included. Asthma Control Questionnaire-6 scores of 0.75 or lower and greater than 0.75 indicated well-controlled asthma (WCA) and ICA. Percent predicted values of IOS parameters and IOS reference values for upper and lower limits of normal (>95th and <5th percentiles, respectively) were calculated on the basis of previously published equations. There were no significant differences in all spirometric indices between the WCA (n= 59) and the ICA (n= 101) groups. The % predicted values of IOS parameters except resistance at 20 Hz (R20) were significantly different between the 2 groups. Receiver operating characteristic analysis showed that the highest and lowest areas under the curve were 0.81 and 0.67 for the difference between the resistances at 5 Hz and 20 Hz (R5-R20) and R20 in discrimination of ICA versus WCA. The areas under the curve for IOS parameters were improved by combination with FeNO. The better discriminative ability of IOS was also supported by the higher values of the concordance index for the resistance at 5 Hz (R5), R5-R20, the reactance at 5 Hz (X5), and the resonant frequency of reactance than those for spirometric parameters. Compared with those with normal values, subjects with abnormal IOS parameters or high FeNO had significantly higher odds of having ICA. The IOS parameters and FeNO were shown to be useful in identifying children with ICA when spirometry was normal.

Impulse oscillometry indices in relation to respiratory symptoms and spirometry in the Swedish Cardiopulmonary Bioimage Study.

Impulse oscillometry (IOS) is sensitive in detecting lung function impairment. In small studies, impaired IOS relates better to respiratory symptoms than spirometry. We studied how IOS related to spirometry and respiratory symptoms in a large population of individuals (n=10 360) in a cross-sectional analysis. Normal values for IOS and spirometry were defined in healthy, never-smoking individuals, aged 50-64 years, from the Swedish CArdioPulmonary bioImage Study (n=3664 for IOS and 3608 for spirometry). For IOS, abnormal values for resistance at 5 Hz (R5) and at 20 Hz and area of reactance were defined using the 95th percentile. Abnormal reactance at 5 Hz for IOS and abnormal conventional spirometry indices (forced expiratory volume in 1 s (FEV1), forced and slow vital capacity and their ratios) were defined using the 5th percentile. Abnormal IOS parameters were found in 16% of individuals and were associated with increased odds ratios for nearly all respiratory symptoms when adjusted for age, gender and smoking. In individuals with normal spirometry, abnormal IOS resistance was related to cough and dyspnoea, while abnormal reactance was related to wheeze. In these individuals, the combination of abnormal R5 with abnormal reactance resulted in approximately two-fold higher likelihood for having cough, chronic bronchitis and dyspnoea, even when further adjusting for FEV1, expressed as % predicted. Abnormal IOS is related to increased respiratory burden in middle-aged individuals with normal spirometry, especially when resistance and reactance parameters are combined. The different relationships between respiratory symptoms and reactance and resistance warrant further research.

Impact of Aerobika® oscillating positive expiratory pressure in improving small airway resistance, lung function, symptoms and exercise capacity in chronic obstructive pulmonary disease.

Aerobika® oscillating positive expiratory pressure (OPEP) device promotes airway clearance in many respiratory diseases. However, studies have yet to focus on its effectiveness in improving small airway resistance via impulse oscillometry (IOS) measurement in COPD subjects. We aim to evaluate the improvement of small airway resistance (via IOS), lung function (spirometry), exercise capacity [via 6-min walking test (6MWT)], symptoms [COPD assessment test (CAT)] and severe exacerbation events among COPD subjects using Aerobika® OPEP. This was a prospective, single-arm interventional study among COPD subjects with small airway disease. Subjects were instructed to use twice daily Aerobika® OPEP (10 min each session); for 24 weeks; as an additional to standard therapy. IOS, spirometry, 6MWT, CAT score and severe exacerbation events were evaluated at baseline, 12 weeks and 24 weeks. Fifty-three subjects completed the study. Aerobika® usage showed improvement of IOS parameters; e.g. measurement of airway resistance at 5 Hz (R5), cmH20/L/s, (12-week p = 0.008, 24-week p < 0.001), R5% predicted (12-week p = 0.007, 24-week p < 0.001) and small airway resistance (R5-R20), cmH20/L/s, (12-week p = 0.021, 24-week p < 0.001). There were improvement of lung function; e.g. FEV1, L (12-week p = 0.018, 24-week p = 0.001), FEV1% predicted (12-week p = 0.025, 24-week p = 0.001), FEF25-75, L (12-week p = 0.023, 24-week p = 0.002), and FEF25-75% predicted (12-week p = 0.024, 24-week p < 0.001). CAT score improved at 12 weeks (p < 0.001) and 24 weeks (p < 0.001). Subjects had improved exercise capacity (6MWT, metres) after 24 weeks (p = 0.016). However, there was no significant difference in severe exacerbation events 24 weeks before and after Aerobika® usage. Aerobika® OPEP demonstrated significant improvement in small airway resistance as early as 12 weeks of usage, with sustained improvement at 24 weeks. Aerobika® OPEP administration had significantly improved lung function, 6MWT, and CAT scores over 24 weeks. There was no difference in severe exacerbation events.

Pulmonary Function Test and Obstructive Sleep Apnea Hypopnea Syndrome in Obese Adults: A Retrospective Study.

We explore risk factors related to severe obstructive sleep apnea (OSA) in obese patients, including pulmonary ventilation function, diffusion function, and impulse oscillometry (IOS) data. The medical records of 207 obese patients who were prepared to undergo bariatric surgery in a hospital from May 2020 to September 2021 were retrospectively reviewed. Polysomnography (PSG), pulmonary ventilation function, diffusion function, and IOS parameters were collected according to the ethical standards of the institutional research committee (registration number: KYLL-202008-144). Logistic regression analysis was used to analyze the related independent risk factors. There were significantly statistical difference in a number of pulmonary ventilation and diffusion function parameters among the non-OSAHS group, the mild-to-moderate OSA group, and the severe OSA group. However, only airway resistance parameters R5%, R10%, R15%, R20%, R25%, and R35% increased with increasing OSA severity and were positively correlated with apnea hypopnea index (AHI). Age (P = 0.012, 1.104 (1.022, 1.192)), body mass index (P< 0.0001, 1.12 (1.057, 1.187)), gender (P = 0.003, 4.129 (1.625, 10.49)), and R25% (P = 0.007, 1.018 (1.005, 1.031)) were independent risk factors for severe OSA. In patients aged 35 to 60, RV/TLC (P = 0.029, 1.272 (1.025, 1.577)) is an independent risk factor for severe OSA. R25% was an independent risk factor for severe OSA in obese individuals, while RV/TLC was also an independent risk factor in those aged 35 to 60. Pulmonary function tests (PFTs), particularly IOS levels, are recommended to assess severe OSA in obese patients.

Comparative assessment of small airway dysfunction by impulse oscillometry and spirometry in chronic obstructive pulmonary disease and asthma with and without fixed airflow obstruction.

Small airways play a major role in the pathogenesis and prognosis of chronic obstructive pulmonary disease (COPD) and asthma. More data on small airway dysfunction (SAD) using spirometry and impulse oscillometry (IOS) in these populations are required. The objective of this study was to compare the two methods, spirometry and IOS, for SAD detection and its prevalence defined by spirometry and IOS in subjects with COPD and asthma with and without fixed airflow obstruction (FAO). This is a cross-sectional study. Spirometric and IOS parameters were compared across four groups (COPD, asthma with FAO, asthma without FAO, and healthy subjects). SAD defined by spirometry and IOS criteria were compared. A total of 262 subjects (67 COPD, 55 asthma with FAO, 101 asthma without FAO, and 39 healthy controls) were included. The prevalence of SAD defined by using IOS and spirometry criteria was significantly higher in patients with COPD (62.7 and 95.5%), asthma with FAO (63.6 and 98.2%), and asthma without FAO (38.6 and 19.8%) in comparison with healthy control (7.7 and 2.6%). IOS is more sensitive than spirometry in the detection of SAD in asthma without FAO (38.6% vs. 19.8%, p = 0.003) However, in subjects with FAO (COPD and asthma with FAO), spirometry is more sensitive than IOS to detect SAD (95.5% vs. 62.7%, p < 0.001 and 98.2% vs. 63.6%, p < 0.001, respectively). Small airway dysfunction was significantly detected in COPD and asthma with and without FAO. Although IOS shows more sensitivity than spirometry in the detection of SAD in asthma without FAO, spirometry is more sensitive than IOS in patients with FAO including COPD and asthma with FAO.

An explorative study on respiratory health among operators working in polymer additive manufacturing.

In total, 18 subjects working with different additive manufacturing techniques and production of filament with polymer feedstock and 20 controls participated in the study. Study subjects filled out a questionnaire and underwent blood and urine sampling, spirometry, impulse oscillometry (IOS), exhaled NO test (FeNO), and collection of particles in exhaled air (PEx), and the exposure was assessed. Analysis of exhaled particles included lung surfactant components such as surfactant protein A (SP-A) and phosphatidylcholines. SP-A and albumin were determined using ELISA. Using reversed-phase liquid chromatography and targeted mass spectrometry, the relative abundance of 15 species of phosphatidylcholine (PC) was determined in exhaled particles. The results were evaluated by univariate and multivariate statistical analyses (principal component analysis). Exposure and emission measurements in AM settings revealed a large variation in particle and VOC concentrations as well as the composition of VOCs, depending on the AM technique and feedstock. Levels of FeNO, IOS, and spirometry parameters were within clinical reference values for all AM operators. There was a difference in the relative abundance of saturated, notably dipalmitoylphosphatidylcholine (PC16:0_16:0), and unsaturated lung surfactant lipids in exhaled particles between controls and AM operators. There were no statistically significant differences between AM operators and controls for the different health examinations, which may be due to the low number of participants. However, the observed difference in the PC lipid profile in exhaled particles indicates a possible impact of the exposure and could be used as possible early biomarkers of adverse effects in the airways.

Impulse oscillometry in preschool children with persistent asthma can predict spirometry at school age.

Lung function in children with persistent asthma may be impaired during preschool and school ages. The aim of this study was to describe if some preschool impulse oscillometry(IOS) parameters are related to spirometry alterations on reaching school age. In 66 diagnosed with persistent asthma, an IOS was performed at entrance and followed-up to school age where a spirometry was done. The mean age was 4.9 years at the first evaluation and 7.9 years at the second evaluation, and 59.1% were male. During preschool, R5, R20, Fres, AX, and D5-20 were found to have diagnostic accuracy (area under the curve > 0.7) for predicting abnormal spirometry during school age (defined as FEV1 and/or FEV/FVC and/or FVC values below the lower limit of normality according to Quanjer predictive values). AX, D5-20, and R5 had the best LR+ to increase the probability of abnormal spirometry (50, 10, and 7.1, respectively). R20, R5, and AX was the best IOS parameters for discriminating bronchodilator response (BDR) in schoolchildren (LR+ = 3.4, 2.9, and 2.8, respectively). The findings of this study indicate that some IOS parameters between 3 and 5 years of age are useful for predicting abnormal spirometry and BDR at school age.

Clinical characteristics of airway impairment assessed by impulse oscillometry in patients with chronic obstructive pulmonary disease: findings from the ECOPD study in China

BackgroundThe role of airway impairment assessed by impulse oscillometry (IOS) in patients with chronic obstructive pulmonary disease (COPD) remains unclear. Therefore, this study aimed to analyze the proportion and clinical characteristics of airway impairment assessed by IOS across COPD severities, and explore whether airway impairment is a subtype of COPD.MethodsThis study was based on cross-sectional data from the ECOPD cohort in Guangdong, China. Subjects were consecutively recruited from July 2019 to August 2021. They filled out questionnaires and underwent lung function tests, IOS and computed tomography (CT). COPD was defined as post-bronchodilator forced expiratory volume in one second/forced vital capacity < lower limit of normal (LLN). Meanwhile, airway impairment was defined as IOS parameters > upper limit of normal or < LLN. On the one hand, Poisson regression was employed to analyze the associations between acute exacerbations of COPD (AECOPD) in the previous year and airway impairment. On the other hand, logistic regression was used to assess differences in CT imaging between patients with IOS parameters’ abnormalities and patients with normal IOS parameters.Results768 COPD subjects were finally enrolled in the study. The proportion of airway impairment assessed by R5, R20, R5–R20, X5, AX, and Fres was 59.8%, 29.7%, 62.5%, 52.9%, 60.9% and 67.3%, respectively. Airway impairment assessed by IOS parameters (R5, R5–R20, X5, AX, and Fres) in patients with COPD was present across all severities of COPD, particularly in GOLD 3–4 patients. Compared with patients with normal IOS parameters, patients with IOS parameters’ abnormalities had more respiratory symptoms, more severe airway obstruction and imaging structural abnormalities. Patients with IOS parameters’ abnormalities assessed by R5 [risk ratio (RR): 1.58, 95% confidential interval (CI): 1.13–2.19, P = 0.007], R5–R20 [RR: 1.73, 95%CI: 1.22–2.45, P = 0.002], X5 [RR: 2.11, 95%CI: 1.51–2.95, P < 0.001], AX [RR: 2.20, 95%CI: 1.53–3.16, P < 0.001], and Fres [RR: 2.13, 95%CI: 1.44–3.15, P < 0.001] had a higher risk of AECOPD in the previous year than patients with normal IOS parameters.ConclusionsAirway impairment assessed by IOS may be a subtype of COPD. Future studies are warranted to identify the underlying mechanisms and longitudinal progression of airway impairment.

Airway morphological abnormalities of bronchiolitis assessed by endobronchial optical coherence tomography.

A few studies have reported the medium-sized and small airway morphological abnormalities of bronchiolitis. Whether spirometry or impulse oscillometry (IOS) is correlated with airway remodeling of bronchiolitis remains unclear. Aiming to demonstrate the airway morphological abnormalities of bronchiolitis obliterans (BO) and diffuse panbronchiolitis (DPB) assessed by endobronchial optical coherence tomography (EB-OCT), and elucidate whether spirometric and IOS parameters have correlation with the airway remodeling of bronchiolitis. We recruited 18 patients with bronchiolitis (BO, n = 9; DPB, n = 9) and 17 control subjects. Assessments of clinical features, St. George's respiratory questionnaire (SGRQ), chest computed tomography (CT), spirometry, IOS, and EB-OCT were performed in all enrolled subjects. The correlation between EB-OCT and lung function parameters was studied and analyzed. The magnitude of abnormalities of spirometric and IOS parameters was significantly greater in patients with bronchiolitis than that in control subjects (p < 0.05). Patients with BO had notably lower forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, maximal mid-expiratory flow (MMEF)% pred and higher resonant frequency (Fres), and area of reactance (AX) than those with DPB (p < 0.05). The EB-OCT measurement among patients with bronchiolitis and between the bronchus in the left and the right lung demonstrated a heterogeneous distribution of airway calibers, presenting a high intra- and inter-individual variability. Patients with bronchiolitis had notably greater airway wall area (p < 0.05) compared with control, while BO presented greater magnitude of airway abnormalities than DPB. Fres and the difference in airway resistance at 5 and 20 Hz (R5-R20) correlated negatively with medium-sized and small airway inner area, and correlated positively with airway wall area (p < 0.05), whose correlation coefficients were higher than those of spirometric parameters. Bronchiolitis, BO and DPB, manifested a heterogeneous distribution of airway calibers with significant intra- and inter-individual variability. IOS parameters, rather than spirometry, correlated better with medium-sized and small airway remodeling in bronchiolitis assessed by EB-OCT measurement.

Increased airway resistance among exclusive waterpipe smokers detected using impulse oscillometry.

Waterpipe smoking is increasing in popularity, yet the evidence implicating waterpipe smoking in lung disease is limited. We hypothesized that impulse oscillometry (IOS) would detect airway abnormalities in waterpipe smokers (WPS). We studied 210 participants, 40 years or older, from the community, of whom 92 were exclusive WPS and 118 were never-smokers. Waterpipe smoking history was assessed using a validated questionnaire. All participants underwent spirometry, and IOS and absolute and percentage predicted results (for age, sex, height, and weight) were compared between WPS and nonsmokers. The association of IOS parameters with waterpipe smoking duration and extent (waterpipe smoked/day * smoking duration) was evaluated using linear regression. WPS smoked on average 1.8 ± 1.2 waterpipes/day, over an average duration of 23.3 ± 39.8 years. WPS and nonsmokers were largely asymptomatic and had similar age, body mass index, sex distribution, and spirometric values. Nevertheless, WPS had higher IOS measured resistance at 5Hz compared to nonsmokers, (0.53 ± 0.2 vs. 0.48 ± 0.2 kPa/L/s, P = 0.03) and higher percentage-predicted resistance (124.5 ± 36.3 vs. 115.7% ± 35.6%, P = 0.04). Waterpipe smoking duration was also associated with resistance (β = 0.04 kPa/L/s/year, P = 0.01) and with percentage-predicted resistance (β = 0.05/year, P = 0.02). Waterpipe smoking extent was associated with resistance (β = 0.009 kPa/L/s/waterpipe-year, P = 0.04), while the association with percentage-predicted resistance was near significance (β = 0.009/waterpipe-year, P = 0.07). Waterpipe smoking is associated with increased airway resistance assessed by IOS but not by spirometry in largely asymptomatic individuals from the community.