Conventional Lung Function Research Articles

Lung clearance index: A sensitive measure of airway function improvement in adolescents after weight loss from bariatric surgery.

Morbid obesity in adolescents impacts respiratory function, often leading to reduced lung volume and obstructive ventilatory defects. However, standard spirometric values frequently remain within normal ranges. We hypothesized that Lung Clearance Index (LCI) is a more sensitive marker for detecting airway dysfunction in adolescents with morbid obesity than conventional lung function tests. A prospective single-center cohort study evaluated adolescents with morbid obesity undergoing laparoscopic sleeve gastrectomy (LSG). Assessments included fractional exhaled nitric oxide, multiple breath washout, spirometry, plethysmography, diffusion capacity, and a 6-min walk test, conducted pre- and post-surgery. Seventeen adolescents (mean age 17.1 years, BMI 45.5kg/m2) were studied. Pre-surgery, LCI was slightly elevated (mean 7, SD±0.7), other lung function measures were normal. LCI correlated with BMI (r=0.637, p=0.014), no correlation was found between FEV1 and BMI (r=-0.083, p=0.752). Post-surgery, mean LCI fell from 7 (±0.7) to 6.5 (±0.7), p=0.009. The pre-operatively observed correlation between LCI and BMI was no longer present post-operatively (r=0.362, p=0.225). LCI changes (r=0.676, p=0.011) correlated with BMI changes, whilst FEV1 did not (r=0.160, p=0.540). LCI appeared to be a more sensitive marker than conventional spirometry for detecting airway dysfunction in adolescents with morbid obesity. Significant post-surgery improvements suggested enhanced ventilation homogeneity. LCI may detect subtle airway changes in this population, and be potentially valuable for both clinical assessment and research.

Diagnostic efficacy of serum 14-3-3β protein combined with fractional exhaled nitric oxide and conventional ventilatory lung function parameters for bronchial asthma in children

To explore the diagnostic efficacy of serum 14-3-3β protein combined with fractional exhaled nitric oxide (FeNO) and conventional ventilatory lung function parameters in diagnosing bronchial asthma (referred to as "asthma") in children. A prospective study included 136 children initially diagnosed with asthma during an acute episode as the asthma group, and 85 healthy children undergoing routine health checks as the control group. The study compared the differences in serum 14-3-3β protein concentrations between the two groups, analyzed the correlation of serum 14-3-3β protein with clinical indices, and evaluated the diagnostic efficacy of combining 14-3-3β protein, FeNO, and conventional ventilatory lung function parameters for asthma in children. The concentration of serum 14-3-3β protein was higher in the asthma group than in the control group (P<0.001). Serum 14-3-3β protein showed a positive correlation with the percentage of neutrophils and total serum immunoglobulin E, and a negative correlation with conventional ventilatory lung function parameters (P<0.05). Cross-validation of combined indices showed that the combination of 14-3-3β protein, FeNO, and the percentage of predicted value of forced expiratory flow at 75% of lung volume had an area under the curve of 0.948 for predicting asthma, with a sensitivity and specificity of 88.9% and 93.7%, respectively, demonstrating good diagnostic efficacy (P<0.001). The model had the best extrapolation. The combination of serum 14-3-3β protein, FeNO, and the percentage of predicted value of forced expiratory flow at 75% of lung volume can significantly improve the diagnostic efficacy for asthma in children. Citation:Chinese Journal of Contemporary Pediatrics, 2024, 26(7): 723-729.

Impulse oscillometry for the evaluation and management of pediatric asthma

Asthma is the most common chronic disease during childhood. While most of characteristic structural changes in asthma have been identified in the large airways, there is a growing recognition of peripheral airway dysfunction as a crucial factor in the development of asthma. This dysfunction is a defining feature in adults with persistent asthma. However, little is known about the contribution of small airway impairment in children with asthma due to the relatively low sensitivity of conventional lung function tests, such as spirometry. Recently, new diagnostic tools that are sensitive to both large and small airway function and inflammation have been introduced in clinical practice. The most widely studied of these tools in preschool and school-aged children is impulse oscillometry (IOS). This review addresses the latest findings on the usefulness of IOS in identifying small airway dysfunction, predicting the risk of uncontrolled asthma, and ultimately improving the diagnosis and management of asthma in children.

Long-term pulmonary outcome of children with congenital diaphragmatic hernia: functional lung MRI using matrix-pencil decomposition enables side-specific assessment of lung function

ObjectivesIn patients with congenital diaphragmatic hernia (CDH) the exact functional outcome of the affected lung side is still unknown, mainly due to the lack of spatially resolved diagnostic tools. Functional matrix-pencil decomposition (MP-) lung MRI fills this gap as it measures side-specific ventilation and perfusion. We aimed to assess the overall and side-specific pulmonary long-term outcomes of patients with CDH using lung function tests and MP-MRI.MethodsThirteen school-aged children with CDH (seven with small and six with large defect-sized CDH, defined as > 50% of the chest wall circumference being devoid of diaphragm tissue) and thirteen healthy matched controls underwent spirometry, multiple-breath washout, and MP-MRI. The main outcomes were forced expiratory volume in 1 second (FEV1), lung clearance index (LCI2.5), ventilation defect percentage (VDP), and perfusion defect percentage (QDP).ResultsPatients with a large CDH showed significantly reduced overall lung function compared to healthy controls (mean difference [95%-CIadjusted]: FEV1 (z-score) −4.26 [−5.61, −2.92], FVC (z-score) −3.97 [−5.68, −2.26], LCI2.5 (TO) 1.12 [0.47, 1.76], VDP (%) 8.59 [3.58, 13.60], QDP (%) 17.22 [13.16, 21.27]) and to patients with a small CDH. Side-specific examination by MP-MRI revealed particularly reduced ipsilateral ventilation and perfusion in patients with a large CDH (mean difference to contralateral side [95%-CIadjusted]: VDP (%) 14.80 [10.50, 19.00], QDP (%) 23.50 [1.75, 45.20]).ConclusionsData indicate impaired overall lung function with particular limitation of the ipsilateral side in patients with a large CDH. MP-MRI is a promising tool to provide valuable side-specific functional information in the follow-up of patients with CDH.Clinical relevance statementIn patients with congenital diaphragmatic hernia, easily applicable MP-MRI allows specific examination of the lung side affected by the hernia and provides valuable information on ventilation and perfusion with implications for clinical practice, making it a promising tool for routine follow-up.Key Points• Functional matrix pencil decomposition (MP) MRI data from a small sample indicate reduced ipsilateral pulmonary ventilation and perfusion in children with large congenital diaphragmatic hernia (CDH).• Easily applicable pencil decomposition MRI provides valuable side-specific diagnostic information on lung ventilation and perfusion. This is a clear advantage over conventional lung function tests, helping to comprehensively follow up patients with congenital diaphragmatic hernia and monitor therapy effects.

Small airway dysfunction and obesity in asthmatic patients: a dangerous liaison?

Asthma is a chronic condition characterized by inflammation throughout the entire bronchial airways. Recent findings suggest that ventilation inhomogeneity and small airway dysfunction (SAD) play a particularly significant role in asthma development and clinical manifestations. Obesity is a considerable risk factor for asthma development and morbidity in children and adults. A growing body of evidence suggests that SAD is linked to more severe asthma and poor asthma control in obese patients. However, the knowledge about the relationship between peripheral airway compromise and obesity in asthma is limited, mainly because of the historical lack of access to non-invasive assessment methods for studying SAD. Conventional lung function measurements, like spirometry, cannot accurately assess small airway function. However, in recent years, new specialized tests available in outpatient settings have been found to distinguish SAD from large airway obstruction more accurately compared to spirometry. Therefore, understanding the degree of peripheral airway implication in the underlying pathology is critical for effective asthma control and therapeutic decisions. This review highlights recent findings on the impact of SAD on asthma patients who are obese. Additionally, it explores how new diagnostic methods, such as impulse oscillometry (IOS), may be used in outpatient settings to detect small airway impairment in obese asthma at an early stage, potentially leading to improved asthma treatment.

The effects of benralizumab on airway geometry and dynamics in severe eosinophilic asthma: a single-arm study design exploring a functional respiratory imaging approach

BackgroundSevere eosinophilic asthma (SEA) is characterised by elevated blood/sputum eosinophil counts and airway inflammation, which can lead to mucus plug-mediated airway obstruction, increased exacerbation frequency, declines in lung function, and death. Benralizumab targets the alpha-subunit of the interleukin-5 receptor found on eosinophils, leading to rapid and near complete eosinophil depletion. This is expected to result in reduced eosinophilic inflammation, reduced mucus plugging and improved airway patency and airflow distribution.MethodsBURAN is an interventional, single-arm, open-label, uncontrolled, prospective, multicentre study during which participants will receive three 30 mg subcutaneous doses of benralizumab at 4-week intervals. This study will use functional respiratory imaging (FRI), a novel, quantitative method of assessing patients’ lung structure and function based on detailed, three-dimensional models of the airways, with direct comparison of images taken at Weeks 0 and 13. Patients aged ≥ 18 years with established SEA who may be receiving oral corticosteroids and/or other asthma controller medications, who are inadequately controlled on inhaled corticosteroid-long-acting β2-agonist therapies and who have had ≥ 2 asthma exacerbations in the previous 12 months will be included. The objectives of BURAN are to describe changes in airway geometry and dynamics, measured by specific image-based airway volume and other FRI endpoints, following benralizumab therapy. Outcomes will be evaluated using descriptive statistics. Changes in FRI parameters, mucus plugging scores and central/peripheral ratio will be quantified as mean percent change from baseline (Week 0) to Week 13 (± 5 days) and statistical significance will be evaluated using paired t-tests. Relationships between FRI parameters/mucus plugging scores and conventional lung function measurements at baseline will be assessed with linear regression analyses for associations between outcomes, scatterplots to visualise the relationship, and correlation coefficients (Spearman’s rank and Pearson’s) to quantify the strength of these associations.ConclusionsThe BURAN study will represent one of the first applications of FRI—a novel, non-invasive, highly sensitive method of assessing lung structure, function and health—in the field of biologic respiratory therapies. Findings from this study will increase understanding of cellular-level eosinophil depletion mechanisms and improvements in lung function and asthma control following benralizumab treatment.Trial registration EudraCT: 2022-000152-11 and NCT05552508

Evaluation of lung function in a German single center cohort of young patients with sickle cell disease using EIT and standard techniques.

Sickle cell disease (SCD) is a very common autosomal recessive hemoglobinopathy leading to multiple pulmonary complications that are closely associated with mortality. The pathophysiology of chronic pulmonary involvement is not yet fully understood and no specific therapies are available. The aim of this cross-sectional study was to characterize the lung function of children and young adolescents with SCD in a German single-center cohort and to extend conventional lung function testing by the use of a new imaging method. We performed spirometry and body plethysmography in 35 children and young adults with hemoglobin SS, SC, S/β-thalassemia as well as 50 controls. These data were compared with clinical characteristics and typical laboratory parameters of hemolysis and disease activity in SCD. To identify lung inhomogeneities, for example due to atelectasis, hyperinflation, air trapping or vascular occlusions, we used the promising new method of electrical impedance tomography (EIT) and calculated global inhomogeneity indices. Lung function of patients with SCD was significantly reduced compared to that of healthy controls. When the result was found to be pathological, the most commonly observed type of breathing disorder was classified as restrictive. Laboratory parameters showed typical features of SCD including decreased levels of hemoglobin and hematocrit and elevated levels of leucocytes, platelets, lactate dehydrogenase and total bilirubin. However, there was no correlation between blood values and reduced lung function. Electrical impedance tomography (EIT) revealed no abnormalities in SCD patients compared to healthy controls. In particular, we were unable to demonstrate any regional inhomogeneities in lung ventilation. In our study, SCD patients showed impaired lung function, with a relevant percentage of patients suffering from restrictive breathing disorder. Signs of obstruction could not be detected. Electrical impedance tomography (EIT) measurements revealed no unevenness that would suggest air entrapment, blockage of blood vessels, excessive inflation, obstruction, or other forms of lung disease. Additionally, the reduction in lung function observed in SCD patients was not related to the disease severity or laboratory test results.

Adherence, reliability, and variability of home spirometry telemonitoring in cystic fibrosis.

Forced spirometry is the gold standard to assess lung function, but its accessibility may be limited. By contrast, home spirometry telemonitoring allows a multi-weekly lung function follow-up but its real-life adherence, reliability, and variability according to age have been poorly studied in patients with CF (PwCF). We aimed to compare real-life adherence, reliability and variability of home spirometry between children, teenagers and adults with CF. This real-life observational study included PwCF followed for six months in whom lung function (i.e, forced expiratory volume maximum in 1 s (FEV1), forced vital capacity (FVC), forced mid-expiratory flow (FEF) and FEV1/FVC ratio) was monitored by both conventional and home spirometry between July 2015 and December 2021. The adherence, reliability and variability of home spirometry was assessed in all PwCF and compared between children (<12years old), teenagers (12-18 years old) and adults. 174 PwCF were included (74 children, 43 teenagers and 57 adults). Home spirometry was used at least one time per week by 64.1 ± 4.9% PwCF, more frequently in children and teenagers than in adults (79.4 ± 2.9%, 69.2 ± 5.5% and 40.4 ± 11.5% respectively). The reliability to conventional lung function testing was good for all assessed parameters (e.g., FEV1: r = 0.91, p < 0.01) and the variability over the 6 months of observation was low (FEV1 coefficient of variation = 11.5%). For each parameter, reliability was better, and the variability was lower in adults than in teenagers than in children. Home spirometry telemonitoring appears to be a reliable tool for multi-weekly lung function follow-up of PwCF.

Impulse oscillometry system for assessing small airway dysfunction in pediatric bronchiolitis obliterans; association with conventional pulmonary function tests.

Impulse oscillometry system (IOS) is a simple, and less invasive method for assessing small to total airway resistance in children. We analyzed the correlation between IOS, spirometry, and plethysmographic parameters performed for the diagnosis of pediatric BO patients. A total of 89 IOS assessments of pediatric BO patients or children without lung disease were included, and the relationship between pulmonary function tests (PFTs) and diagnostic performance was analyzed. R5, R5-20, X5, and AX were statistically significantly worse in the BO group. In general linear correlation analysis, R5% (adjusted β [aβ], -0.59; p < 0.001) and AX % (aβ, -0.9; p < 0.001) showed the strongest correlation with conventional PFT parameters. R5% and AX % also showed the highest correlation with FEF25-75% (aβ, -0.48; p < 0.001 and aβ, -0.83; p < 0.001), and sRaw % (aβ, -0.73; p = 0.003 and aβ, -0.59; p = 0.008, respectively). Multivariate logistic regression analysis showed that R5 Z-score showed the highest ORs with FEV1 (OR = 3.94, p = 0.006), FEF25-75% (OR = 5.96, p = 0.005), and sRaw % (OR = 4.85, p = 0.022). Receiver operating curve analysis suggested AX % and R5% as the most optimal IOS parameters for BO diagnostic performance with the area under the curve of 0.915 and 0.882, respectively. In conclusion, R5 and AX are the parameters that can independently identify the severity of airway obstruction in pediatric BO patients without conventional lung function tests. IOS is an easy-to-perform, and reliable diagnostic method capable of detecting pathological obliteration of the small airways in children with BO.

Airspace Dimension Assessment with Nanoparticles (AiDA) in Comparison to Established Pulmonary Function Tests.

BackgroundAirspace Dimensions Assessment with nanoparticles (AiDA) is a new method for non-invasive measurement of pulmonary distal airspaces. The aim of this study was to compare AiDA measurements with other pulmonary function variables to better understand the potential of AiDA in a clinical context.MethodsAiDA measurements and pulmonary function tests were performed in 695 subjects as part of the Swedish CArdioPulmonary bioImage Study. The measurement protocol included spirometry, measurement of diffusing capacity of carbon monoxide, oscillometry and pulmonary computed tomography. AiDA indices were compared to all other pulmonary examination measurements using multivariate statistical analysis.ResultsOur results show that AiDA measurements were significantly correlated with other pulmonary function examination indices, although covariance was low. We found that AiDA variables explained variance in the data that other lung function variables only influenced to a minor extent.ConclusionWe conclude that the AiDA method provides information about the lung that is inaccessible with more conventional lung function techniques.

Protective potential of high-intensity interval training on cardiac structure and function after COVID-19: protocol and statistical analysis plan for an investigator-blinded randomised controlled trial

IntroductionCOVID-19 is associated with a marked systemic inflammatory response with concomitant cardiac injury and remodelling, but it is currently unknown whether the latter is reversible. Given that high-intensity interval training...

Multiple breath washout: measuring early manifestations of lung pathology.

The multiple breath washout (MBW) test measures the efficiency of gas mixing in the lungs and has gained significant interest over the past 20 years. MBW outcomes detect early lung function impairment and peripheral airway pathology, through its main outcome measure lung clearance index (LCI). LCI measures the number of lung turnovers required to washout an inert tracer gas. MBW is performed during normal (tidal) breathing, making it particularly suitable for young children or those who have trouble performing forced manoeuvres. Additionally, research in chronic respiratory disease populations has shown that MBW can detect acute clinically relevant changes before conventional lung function tests, such as spirometry, thus enabling early intervention. The development of technical standards for MBW and commercial devices have allowed MBW to be implemented in clinical research and potentially routine clinical practice. Although studies have summarised clinimetric properties of MBW indices, additional research is required to establish the clinical utility of MBW and, if possible, shorten testing time. Sensitive, feasible measures of early lung function decline will play an important role in early intervention for people living with respiratory diseases.Educational aimTo describe the multiple breath washout test, its applications to lung pathology and respiratory disease, as well as directions for future research.

Evaluation of cardiopulmonary exercise test in the prediction of disease progression in systemic sclerosis.

Cardiopulmonary exercise test (CPET) is a widely used examination to predict the prognosis of many chronic pulmonary diseases, and it has also been tested in systemic sclerosis (SSc) with a focus on the development of pulmonary hypertension. CPET is a highly informative non-invasive tool that provides a more complex information than conventional lung function tests to predict the course of cardiopulmonary diseases, as it provides a general overview of the aerobic metabolism, influenced by pulmonary, cardiovascular and peripheral muscle function. The purpose of this investigation was to assess if the progression and the development of poor overall disease outcome in SSc can be predicted by this method. Twenty-nine SSc patients were investigated prospectively with standard follow-up plus CPET for a mean of 3.7 years to match the results of conventional evaluation modalities and CPET. A composite end-point of several serious outcomes reflecting SSc-related vascular and cardiopulmonary damage was set up, and the predictive value of and correlations between the CPET parameters and resting lung function and echocardiography variables were assessed. None of the clinical parameters, resting lung function or echocardiographic test results proved to be predictive of the development of the endpoint of poor prognosis in this cohort. In contrast, several CPET parameters were found to discriminate between SSc patients with or without adverse outcome. The detection of desaturation (at any CPET test) was associated with a higher risk of poor prognosis (OR:5.265). VO2 and VE/VCO2 at baseline correlated with the annual decrease in FVC, anaerobic threshold with the development of digital ulcers, and VE/VO2 with the increase in pulmonary arterial pressure. Several CPET parameters obtained at the beginning of follow-up are informative of the appearance of various adverse end-points. CPET is a feasible examination in the care of SSc patients and provides excess information to current standard follow-up examinations.

The Relevance of Small Airway Dysfunction in Asthma with Nocturnal Symptoms.

RationaleSmall airway dysfunction (SAD) is a frequent feature of asthma that has been linked to disease severity and poor symptom control. However, little is known about the role of SAD in nocturnal asthma.ObjectiveTo study the association between the severity of SAD and frequency of nocturnal symptoms compared to conventional lung function testing.MethodsWe assessed the frequency of self-reported nocturnal symptoms through the asthma control test. We studied the impact of nocturnal asthma using the Asthma Quality of Life Questionnaire (AQLQ) and the Multidimensional Fatigue Inventory (MFI-20). We assessed the lung function using spirometry, body plethysmography, impulse oscillometry, single and multiple inert gas washout and measured markers of T2-inflammation (blood and sputum eosinophils; fractional exhaled nitric oxide (FeNo)). We stratified the patients according to the presence and frequency of nocturnal asthma.ResultsA total of 166 asthma patients were enrolled in the analysis. Eighty-seven patients (52%) reported to have nocturnal symptoms at least once in the last four weeks. The odds ratio of nocturnal asthma correlated with the severity of all non-spirometric measures of SAD, yet neither with airflow obstruction (FEV1 and FEV/FVC) nor with large airway resistance (R20). Patients with frequent nocturnal asthma (n = 29) had a numerical increase of T2 markers and more severe SAD, as indicated by all non-spirometric measures of SAD (all p-values < 0.05), worse overall asthma control, increased fatigue and reduced quality of life (all p-values < 0.01) compared to patients with infrequent nocturnal asthma (n = 58) or patients without nocturnal asthma (n = 79). We identified 63 patients without airflow obstruction, nearly 43% of them (n = 27) had nocturnal asthma. In this subgroup, only markers of air trapping and ventilation heterogeneity were significantly elevated and correlated with the frequency of nocturnal symptoms: LCI (Spearman’s coefficient = −0.42, p < 0.001), RV% (−0.32, p = 0.02).ConclusionSAD is closely associated to asthma with nocturnal symptoms. Spirometry might underestimate the broad spectrum of distal lung function impairments in this population of patients.

The role of impulse oscillometry in the management of asthma when forced expiratory maneuvers are contraindicated: case series and literature review

Objectives: The impulse oscillometry system (IOS) provides an alternative method of lung function testing for patients in whom forced expiratory manoeuvres are contraindicated, such as those with inherited vascular connective tissue disorders. Here we examine the role of IOS in the diagnosis and monitoring of asthma in such patients through a clinical case series and literature review. Methods: The clinical case series comprised of data from 12 patients with inherited connective tissue disorders representing 32 clinical encounters. Of these, 11 encounters were for asthma diagnosis and 21 were for asthma monitoring. Symptoms, exhaled nitric oxide (FeNO) and IOS were assessed at each encounter. Results: In the clinical case series, 5 of 6 patients with likely asthma (as determined by physician review and exhaled nitric oxide testing) had abnormal IOS parameters compared with 0 of 5 of those with unlikely asthma. In the monitoring group, 11 encounters resulted in treatment escalation (demonstrating suboptimal control), and 8 resulted in no change to treatment (good control). Six of 11 of those with suboptimal control had abnormalities in ≥3 IOS parameters, with R5 and R5-20 most frequently affected. Only 1 of 8 of those with good control had abnormalities in ≥3 IOS parameters. Conclusions: IOS can be used as an alternative to conventional lung function testing to support the diagnosis and monitoring of asthma when forced expiratory manoeuvres are contraindicated. Larger studies are required to establish severity and treatment escalation thresholds and provide clearer comparisons with spirometry values.

Plasma Fibrinogen as a Biomarker of Stable and Exacerbated Chronic Obstructive Pulmonary Disease

Study Design: An experimental, comparative, cross-sectional study Place and Duration of Study: Department of Physiology, Federal Post Graduate Medical Institute (FPGMI), Sheikh Zayed Medical Complex Lahore, Pakistan from August 2013 to 2014 Background: Chronic Obstructive Pulmonary Disease (COPD) is a preventable and treatable disease, but is a partially reversible chronic inflammatory condition characterized by airway obstruction. COPD remains under-diagnosed and under-treated because the only available diagnostic method at present is testing lung functions by spirometry which is not helpful to determine the severity and clinical outcomes of the disease. Circulating biomarkers are under consideration for various diseases worldwide. Plasma fibrinogen is emerging as one of the most promising biomarkers of COPD in smokers. Objective: The objective of this study is to investigate if plasma fibrinogen can serve as a diagnostic biomarker of COPD in smokers, and if its further higher levels are seen in the exacerbated state of the disease in comparison to the stable disease. Materials and Methods: 75 middle-aged to old-age smokers of either gender were selected. Lung functions of every participant were measured to determine Forced Expiratory Volume in the first second (FEV1), Forced Vital Capacity (FVC), and the ratio of FEV1/FVC by spirometry. On the basis of the results of the tests, subjects were divided into three groups; firstly, the control group of chronic smokers without COPD, secondly, smokers with COPD in a stable state, and thirdly, patients in an exacerbated state of COPD. Plasma fibrinogen was quantitatively estimated in every individual of all three groups by the Clauss method using the Hemostat Fibrinogen kit. Results: The average Plasma fibrinogen level was found to be 235.008 mg/dl in healthy smokers (control group), while an average of 440.12mg/dl was measured in patients with stable COPD. The difference in plasma fibrinogen levels was found to be significant, having a p-value of (0.000). In the third group with declined lung function predicting acute exacerbated COPD, fibrinogen was found to be &gt; 453.2 mg/dl, which was significantly higher than in the stable disease group (p-value &gt; 0.0017) Conclusion: Plasma fibrinogen level measurement is a reliable and accessible test in terms of a diagnostic marker of COPD, as compared to conventional lung function testing done in the past.

Small-airway dysfunction in paediatric asthma.

Asthma is a chronic inflammatory airway disorder that can involve the entire bronchial tree. Increasing evidence shows that ventilation heterogeneity and small airway dysfunction are relevant factors in the pathogenesis of asthma and represent a hallmark in adults with persistent asthma. Little is known about the contribution of peripheral airway impairment in paediatric asthma, mainly due to the inaccessibility to evaluation by noninvasive techniques, which have only been widely available in recent years. Emerging evidence suggests that small airways are affected from the early stages of the disease in childhood-onset asthma. Conventional lung function measurement, using spirometry, is unable to sensitively evaluate small airway function and may become abnormal only once there is a significant burden of disease. Recent studies suggest that chronic inflammation and dysfunction in the small airways, as detected with new advanced techniques, are risk factors for asthma persistence, asthma severity, worse asthma control and loss of pulmonary function with age, both in adults and children. Knowing the extent of central and peripheral airway involvement is clinically relevant to achieve asthma control, reduce bronchial hyper-responsiveness and monitor response to asthma treatment. This review outlines the recent evidence on the role of small airway dysfunction in paediatric asthma development and control, and addresses how the use of new diagnostic techniques available in outpatient clinical settings, namely impulse oscillometry and multiple breath washout, could help in the early detection of small airway impairment in children with preschool wheezing and school-age asthma and potentially guide asthma treatment.

ROLE OF NONINVASIVE METHODS FOR ASSESSING STABLE NON-CYSTIC FIBROSIS BRONCHIECTASIS

SESSION TITLE: Obstructive Lung Disease Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Bronchiectasis is characterized by the abnormal dilation of lung airways. Only some patients with bronchiectasis may clinically benefit from the treatment recommended in the guidelines of the European Respiratory Society. The value of noninvasive methods for assessing the clinical phenotypes of stable-state non-cystic fibrosis (non-CF) bronchiectasis for treatable characteristics has not been adequately studied. METHODS: Patients with stable non-CF bronchiectasis were retrospectively enrolled. Patient characteristics, fractional exhaled nitric oxide (FeNO) values, and the results of blood tests for inflammatory markers, pulmonary function test, high-resolution computed tomography (HRCT), and bronchial hyper-responsiveness test or bronchodilator reversibility test were obtained. These data were used to assess the factors associated with the clinical phenotype of bronchiectasis. RESULTS: Eighty-nine patients were enrolled. The majority of the patients were female (60.67%) and have an average age of 59.08±15.09 years old. The predicted percentages of forced expiratory volume in 1 s (FEV1) and the ratio of FEV1 and forced vital capacity were 56.17%±23.16% and 65.58%±15.26%, respectively. Eighteen (20.22%) of the patients with bronchiectasis had emphysema. The presence of emphysema in bronchiectasis was associated with a high airflow obstruction level. Seventeen (10.10%) of the patients with bronchiectasis had asthma. FeNO was significantly higher in the group of patients with bronchiectasis and asthma than in the other two groups (p < 0.01). The erythrocyte sedimentation rate (ESR) of the bronchiectasis alone group was higher than those of the other two groups. Significant negative correlations were found between ERS and FeNO levels (P = 0.02, r = −0.338), between HRCT score and FeNO levels (P = 0.04, r = −0.229), and between FEV1 (% predicted) and HRCT scores (P = 0.0007, r = −0.3629). A significant positive correlation was found between ERS and HRCT scores (P = 0.0001, r = 6326). CONCLUSIONS: A remarkable proportion of patients with bronchiectasis have emphysema or asthma. Biomarkers, such as FeNO, and conventional lung function tests should be routinely used for phenotyping bronchiectasis for potential targeted therapy. ESR can be used as a biomarker to reflect the level of systemic infiammation and the severity of bronchiectasis. These approaches will provide a better understanding of patients with bronchiectasis and their clinical phenotypes and lead to a more individualized and effective therapy. CLINICAL IMPLICATIONS: FeNO and conventional lung function tests are useful for phenotyping bronchiectasis for potential targeted therapy. ESR can be used as a biomarker to reflect the level of systemic infiammation and the severity of bronchiectasis. DISCLOSURES: No relevant relationships by Fengjia Chen, source=Web Response No relevant relationships by Aiping Chen, source=Web Response No relevant relationships by Gengpeng Lin, source=Web Response

Correspondence between Capnovolumetric and Conventional Lung Function Parameters in the Diagnosis of Obstructive Airway Diseases

Background: Capnovolumetry is of interest as a method for the diagnosis of obstructive airway diseases, requiring little cooperation from the patient. Objective: To help in the interpretation of capnovolumetric parameters, we aimed to identify their correspondence to conventional lung function indices. Methods: We studied 978 patients from a diagnostic study with complete functional data and the clinical diagnosis of asthma, chronic obstructive pulmonary disease (COPD), or no respiratory disease. Using path analysis, four capnovolumetric parameters (slope of expiratory phase 3, ratio of slopes of phases 3 and 2, volume of phase 2, and the ratio area/volume of phase 3) previously identified as predictors of airway obstruction in terms of spirometry and body ple­thysmography, were analyzed regarding their relationship to each other and the diagnostic categories of asthma or COPD versus control, or obstruction versus no obstruction. We then identified four lung function parameters showing relationships as much as possible isomorphic to those between capnovolumetric parameters. Results: The four capnovolumetric parameters were related to COPD and obstruction via both direct and indirect influences, but only two of them to asthma. Regarding the correspondence to lung function parameters, the slope of expiratory phase 3 corresponded best to the ratio of residual volume to total lung capacity, the ratio of slopes of phases 3 and 2 to forced expiratory volume in 1 s, the volume of phase 2 to forced expired flow at 50% of vital capacity, and the ratio area/volume of phase 3 to forced vital capacity. Conclusions: Our results indicated an intricate relationship of capnovolumetric parameters to each other and to airway obstruction, asthma, or COPD. The correspondence to conventional lung function measures seemed to reflect the entities lung hyperinflation, overall ventilatory impairment, bronchoconstriction, and ventilated lung volume, in that order. These findings might be helpful for clinicians in the interpretation of capnovolumetry.

The exposure risk of typical VOCs to the human beings via inhalation based on the respiratory deposition rates by proton transfer reaction-time of flight-mass spectrometer.

The respiratory deposition rates are the important analytical parameters for human health risk assessment related to the environmental volatile organic compounds (VOCs). In present study, the deposition rates from the linear regressions of CH2O, CH5N, C2H6O, C2H4O2, C3H8O, C6H6, C7H8, C8H8, and C8H10 of 120 healthy volunteers were obtained with significantly different from the respective calculated deposition rates. The CH2O (formaldehyde) has the highest deposition rate, indicating the highest associated exposure risk of CH2O if the persons are exposed to the same concentrations of these VOCs through inhalation. In order to explore the effects of the breathing models and sampling time on the deposition rates of VOCs, volunteers were first asked to breathe successively with nasal-in-nasal-out, oral-in-nasal-out, and oral-in-oral-out breathing models before and after three meals for three days. Sampling time variation has no effect on the deposition rates of selected VOCs, while the deposition rates of C2H4O2, C3H8O, C6H6, C7H8 and C8H10 by nasal-in-nasal-out were significantly different from oral-in-oral-out and nasal-in-oral-out models. Among all the breathing models, nasal-in-oral-out comprises the entire respiratory system. In order to further validate the results, the deposition rates of the selected VOCs were calculated in 120 healthy volunteers using nasal-in-oral-out breathing model for unlimited time after the conventional lung function examination. Difference in gender and body mass index had no effect on the deposition rates of VOCs, while the age affects the deposition rates of CH2O, CH5N and C2H4O2. Positive correlation analysis between lung function factors and deposition rates revealed that the individuals with larger lung function factors are more susceptible to deposit the VOCs. Overall, the main conclusion can be drawn that the respiratory deposition rates were influenced by the physiological factors. Therefore, the major objective for future research is to accurately calculate the deposition rates of environmental VOCs for health-risk assessment.