Pulmonary functions according to age evaluated using spirometry and impulse oscillometry in patients with neuromuscular disorders

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.

Combining low-frequency oscillometry and spirometry measurements in relation to asthma control and exacerbations in moderate-to-severe asthma

<b>Background:</b> Impulse oscillometry (IOS) is a non-invasive, non effort-dependent method of testing lung function. We hypothize that IOS may be useful in patients with neuromuscular disorders who have restrictive lung function due to weakened respiratory muscles. <b>Objective:</b> To compare IOS to conventional pulmonary function test (PFT) in evaluating lung function in patients with neuromuscular disorders at the Pediatric Pulmonology clinic Method: Patients with diagnosed neuromuscular disorders (Duchenne muscular dystrophy (DMD), spinal muscular atrophy (SMA), other congenital muscular dystrophy(CMD)) who underwent IOS and PFT simultaneously during Jan 2020 – Dec 2020 were included. Correlation between linear variables of IOS and PFT were evaluated. <b>Results:</b> A total of 75 patients were enrolled (54 DMD, 12 SMA, 9 other CMD). Mean age was 20.1 years, and mean height, weight and BMI were 160cm, 48kg, and 20.0 kg/m2, respectively. PFT showed restrictive lung function (FVC&lt;80%predicted) in all participants. Moderate positive correlation existed between FVC and FEV1 %predicted and R5 and R20 %predicted. FVC and FEV1 %predicted were weakly correlated with ΔX5=X5pred-X5. Peak expiratory flow showed strong correlation with R5 and R20 %predicted. <b>Conclusion:</b> In patients with neuromuscular disorders, relatively preserved lung function by PFT was associated with increased airway resistance and reactance measured by IOS.

Although the diagnostic value of impulse oscillometry (IOS) in bronchiectasis for the differential diagnosis of healthy subjects has been researched, the usefulness of each IOS parameter for predicting disease severity in bronchiectasis has not been thoroughly investigated. In addition, the usefulness of IOS in patients with nontuberculous mycobacteria (NTM) infection has not been reported. This study aimed to determine the predictive significance of respiratory impedance and detect the other most significant IOS parameters for predicting disease severity in bronchiectasis patients and to validate the usefulness of IOS in patients with NTM infection.A total of 206 patients with bronchiectasis who attended clinics at the National Hospital Organization Osaka Toneyama Medical Center were included. Chest high-resolution computed tomography, spirometry and IOS were performed. Hospital admissions, mortality and disease severity indices for bronchiectasis (Bronchiectasis Severity Index (BSI), FACED, and E-FACED scores) were calculated to assess disease severity. The patients were divided into subgroups with and without NTM infection, and subgroup analyses were performed.Respiratory reactance, especially resonant frequency (fres), correlated with both BSI and FACED score better than respiratory resistance. Inspiratory but not expiratory impedance was strongly correlated with BSI, FACED and E-FACED scores. Inspiratory fres was the most useful predictor, increasing as the disease became more severe. The usefulness of IOS was almost equivalent in patients both with and without NTM infection.Inspiratory reactance measured by IOS is useful for estimating disease severity in bronchiectasis. Inspiratory fres best predicts disease severity in bronchiectasis patients both with and without NTM infection.

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.

Background: Bronchiectasis is a chronic respiratory condition in which infection, inflammation, and damage of the airways all play a role. Intense airway inflammation is precipitated by pathogenic insults, resulting in chronic airway damage. Impulse oscillometry (IOS) is a noninvasive approach that might offer worldwide information on airway resistance by researching the mechanical waves superimposed upon breathing movements. It has been observed that IOS may differentiate peripheral airways abnormalities in chronic obstructive pulmonary disease (COPD), asthma, interstitial pulmonary disease (ILD) and pulmonary fibrosis (CF) with high degree of precision. Methods: This research was carried out on 40 cases with bronchiectasis diagnosed by HRCT. Such cases were classified into two groups, according to Bronchiectasis Severity Index (BSI)(108): group I: Included 20 cases with mild to moderate bronchiectasis and group II: Included 20 cases with severe bronchiectasis. Cases included in the research were subjected to full history taking and complete physical examination. This includes: Complete blood count (CBC), sputum culture, chest x-ray to exclude cases with other lung diseases, High-Resolution Computerized Tomography (HRCT), that were interpreted for the presence, pattern and distribution of bronchiectasis, arterial blood gases, echocardiography, measuring systolic pulmonary artery pressure, pulmonary function tests (PFT), Impulse Oscillometry and reactance area (AX) were measured. Results: Regarding disease duration, no significant differences was found between both groups while a statistically significant difference was observed between groups regarding the used medications. Regarding laboratory investigations, no significant difference was observed among the groups for any of the measured measurements. Regarding functional assessment data, A statistically evident difference was found between groups in the following: MEF 50%, FEV1% predicted, FEV1/FVC% and FVC% with no significant differences in FEV1. Regarding IOS measurements, A statistically evident difference was found between both groups in R5% predicted while no difference was observed regarding R5 actual, R20, AX, or X5. Positive correlation was very high in between HRCT score and each of FEV1% predicted, FVC (%) AX, R5% predicted, R5 actual, R20 and X5 but negative correlation was very high in between HRCT score and MEF 75%, FEV1/FVC% Conclusions: IOS measurements are markedly increased in cases with bronchiectasis and they are correlated with spirometric measurements and HRCT scores.

The clinical use of impulse oscillometry in neuromuscular diseases

Although spirometry is a standard diagnostic tool for obstructive lung diseases, it is rarely performed, and the quality of basic spirometry is low in many countries. The impulse oscillometry system (IOS) is a non-invasive method that requires minimal patient cooperation and, therefore, can be performed even in the pediatric population. It has been also suggested that IOS may help to clarify the relationship between small airway disease and the underlying mechanisms of chronic obstructive pulmonary disease (COPD). The primary objective of the study was to compare IOS parameters in COPD patients with those in healthy individuals. Our secondary objective was to determine the relationship between IOS parameters and standard pulmonary function tests (PFTs). Our hypothesis was that airway resistance detected by IOS would be higher in COPD patients than in controls. Hence, IOS would provide findings comparable to and correlated with those of standardized PFTs for small airway obstruction. A total of 104 subjects (62 patients with COPD and 42 healthy non-smoking individuals) were included in the study. All subjects underwent spirometry, diffusing capacity for carbon monoxide (DLCO), lung-volume measurements, and IOS. COPD patients showed significant decreases in forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC, FEF 25-75, and DLCOadj, and significant increases in residual volume (RV) and total lung capacity (TLC) compared with the control group. In terms of IOS parameters, R5%, Z5%, Fres, and R5-R20/R5% values were significantly higher in the COPD group (P = 0.029, P = 0.022, P = 0.009, P = 0.004, respectively). The reactance area (AX) value, defined as the AX, was also significantly increased in the COPD group (P = 0.004). The correlation between FEF 25-75% (L/s) and R5-R20 was moderate and negative (r = -0.491, P < 0.001). A weak correlation (r = 0.240, P = 0.017) was also found between the RV/TLC ratio and R5-R20. This study showed that airway resistance was increased in the COPD group and that IOS parameters were associated with measures of small-airway function in standard PFTs. IOS can be used as a non-invasive, patient-friendly method that complements PFTs by providing a comprehensive assessment of COPD pathology and pathophysiological changes and detecting changes in symptomatic patients.

Background Obstructive airway diseases, including chronic obstructive pulmonary disease (COPD) and asthma, pose significant global health challenges. Early and accurate diagnosis is crucial for effective management. Although Spirometry has traditionally been the cornerstone of diagnostics, Impulse Oscillometry (IOS) has emerged as a promising alternative. This study aims to compare the diagnostic performance of Spirometry and IOS in patients attending the Respiratory Medicine Department at the Acharya Vinoba Bhave Rural Hospital, Sawangi, India. Methods A Comparative Observational Study was conducted between August 2022 and August 2024, enrolling patients who met specific inclusion criteria. Data were collected through a comprehensive medical history, clinical examination, routine blood tests, chest radiography, High-resolution computed tomography (HRCT), spirometry, and IOS. Key parameters, including Forced expiratory volume in the first second FEV1, FEV1/FVC (Forced Expiratory Volume), (Forced Expiratory Volume) FVC, (Forced Expiratory Flow) FEF 25-75 for Spirometry, and R5, R20, fres, X5, and AX for IOS, were analyzed using the Chi-Square Test and Student’s t-test with SPSS 27.0 and GraphPad Prism 7.0. Expected outcome The study included 130 participants with the primary objective of evaluating IOS’s diagnostic advantages of IOS over spirometry. Our findings demonstrate that IOS offers enhanced sensitivity for diagnosing early small airway diseases, which is a crucial factor for early diagnosis in both pediatric and adult populations.

Measuring the performance of small airways dysfunction is challenging due to their relative inaccessibility with conventional methods. In recent years, spirometry and impulse oscillometry (IOS) methods have been widely used for their evaluation. The aim of this study was to investigate the relationship between spirometric parameters and IOS in newly diagnosed asthma (NDA) patients. In this cross-sectional study, 100 NDA patients who referred to the allergy Clinic of Masih Daneshvari Hospital between 2021 and 2023 were enrolled. IOS and spirometry tests were performed for all patients. Spirometry measures included forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, and forced expiratory flow (FEF25-75). IOS criteria included R5%, R20%, R5-R20%, X5%, Ax% and FRES. The relationship between spirometry and IOS parameters was evaluated. The mean age was 22.6±9.5 years. None of the 2 techniques had a significant relationship with disease severity. FVC, FEV1/FVC and FEF25-75 indices had a significant positive correlation with all other IOS indices except for Ax. In the comparison of FEF25-75 parameter in spirometry, 4 IOS indices including R5, R20, R5-R20 and X5 had appropriate sensitivity and specificity for predicting asthma. In the comparison of FEF25-75 parameter in spirometry, 4 IOS indices including R5, R20, R5-R20 and X5 had appropriate sensitivity and specificity for predicting asthma. The sensitivity and specificity of R5 for asthma diagnosis were 0.85 and 0.73, respectively. Further multicenter studies with larger sample sizes are recommended to confirm these results.

IntroductionStudies suggest peripheral airway abnormalities in Pulmonary Arterial Hypertension (PAH). Impulse Oscillometry (IOS) is a noninvasive and sensitive technique for assessing the small airways. It evaluates the impedance of the respiratory system ‒ Resistance (R) and reactance (X) ‒ to a pulse of sound waves sent to the lungs, in a range of frequencies (5‒20 Hz). MethodResistance variables: R5, R20, R5-R20 and reactance variables: AX (reactance area) and Fres (resonance frequency). The aim is to evaluate R and X in patients with idiopathic PAH (IPAH) and to investigate whether there is a correlation between IOS and spirometry. ResultsThirteen IPAH patients and 11 healthy subjects matched for sex and age underwent IOS and spirometry. IPAH patients had lower FVC and FEV1 values (p < 0.001), VEF1/CVF (p = 0.049) and FEF 25-75 (p = 0.006) than healthy patients. At IOS, IPAH patients showed lower tidal volumes and higher AX (p < 0.05) compared to healthy individuals, and 53.8 of patients had R5-R20 values ≥ 0.07 kPa/L/s. Correlation analysis: X5, AX, R5-R20 and Fres showed moderate correlation with FVC (p = 0.036 r = 0.585, p = 0.001 r = -0.687, p = 0.005 r = -0.726 and p = 0.027 r = -0.610); Fres (p = 0.012 r = -0.669) and AX (p = 0.006 r = -0.711) correlated with FEV1; [R5 and R20, (R5-R20)] also correlated with FEV1 (p < 0.001 r = -0.573, p = 0.020 r = -0.634 and p = 0.010 r = -0.683, respectively) in the IPAH group. There were also moderate correlations of FEF 25–75 % with Z5 (p = 0.041), R5 (p = 0.018), Fres (p = 0.043) and AX (p = 0.023). DiscussionPatients showed changes suggestive of increased resistance and reactance in the IOS compared to healthy individuals, and the IOS findings showed a good correlation with spirometry variables.

To evaluate the respiratory functions of children with nephrotic syndrome (NS) by impulse oscillometry (IOS) and its correlation with spirometry. Fifty-five NS patients aged 3-18 years were included as the study group and 40 healthy children of the same age formed the control group. Patients were divided into nephrotic phase (first attack and relapse) and remission. Demographic, anthropometric, and laboratory data of the children were recorded. Respiratory functions were evaluated by IOS and spirometry. Children over 6-years old performed both IOS and spirometry while children under 6 years performed only IOS. The R (R5%, R10%, R5-20), AX and Z5% values of IOS in patients with nephrotic phase were higher than remission patients and control group while spirometry indices of PEF% and MEF25-75% were lower. Z scores of MEF25-75 were significantly negatively correlated with z scores of R5, R10, Z5, and Fres while they were significantly positively correlated with z scores of X values (5, 10, 15, and 20 Hz). Z scores of forced expiratory volume in 1 /forced vital capacity significantly negatively correlated with z scores of R values (R5, R10), Z5 and AX and positively correlated with z scores of X values (X5, X10, X15 Hz). Our study demonstrated that respiratory functions measured by IOS and spirometry were affected at the time of nephrotic phase in NS patients. IOS, a novel method easily applicable even in small children, is a potentially valuable tool to detect this condition; given its good correlation with spirometry.

IntroductionIn the field of pulmonary medicine, respiratory mechanics and physiology are obviously affected by most pathological lesions and diseases, either primary disease or part of systemic ones. In the era of rheumatoid arthritis (RA), airway abnormality and interstitial lung pneumonia and/or fibrosis are the most common findings that face physicians during the disease course and affect morbidity, survival, and quality of life of patients with RA. Impulse oscillometry (IOS) is a noninvasive technique that needs minimal patient cooperation, which makes it suitable for any age including even children and can be performed by most patients.Aim of the workTo describe the respiratory measures done by IOS in patients with RA and to correlate them with those measured by spirometry.Patients and methodsA total of 60 patients with RA were recruited in this cross-sectional observational study. They were investigated via pulmonary function assessments, including spirometry and IOS, to measure forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC, and maximal expiratory flow at 25% (MEF 25%)in addition to R5% of predicted, R20% of predicted, R5–20, X5, and area under the curve.ResultsIOS measures indicated increased airway resistance (R5%, R20%, and R5–20) with decreased lung reactance (X5). Moreover, a positive correlation between disease duration and X5, between X5 and area under the curve and each of FEV1%, FVC%, and MEF 25%, whereas a negative correlation between R5–20 and each of FEV1%, FVC%, and MEF 25%.ConclusionIOS is an easy and rapid maneuver that requires minimal patient cooperation. It can identify lung affection in those who have mild or even normal spirometric changes. It is just a good screening test in patients with RA to detect early pathophysiologic lung changes. However, it needs further investigations to clarify the mechanism of these changes.

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%.

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. The study analyzed data from adult patients with persistent symptoms who underwent IOS testing within and after 84 days from the diagnosis date. 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. 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.