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

BACKGROUND

Allergic sensitization and low lung function in early childhood are risk factors for subsequent wheezing and asthma. However, it is unclear how allergic sensitization affects lung function over time.

OBJECTIVE

We sought to test whether allergy influences lung function and whether these factors synergistically increase the risk of continued wheezing in childhood.

METHODS

We analyzed longitudinal measurements of lung function (spirometry and impulse oscillometry) and allergic sensitization (aeroallergen skin tests and serum allergen-specific IgE) throughout early childhood in the Urban Environmental and Childhood Asthma study, which included high-risk urban children living in disadvantaged neighborhoods. Intraclass correlation coefficients were calculated to assess lung function stability. Cluster analysis identified low, medium, and high allergy trajectories, which were compared with lung function and wheezing episodes in linear regression models. A variable selection model assessed predictors at age 5 years for continued wheezing through age 12 years.

RESULTS

Lung function adjusted for growth was stable (intraclass correlation coefficient, 0.5-0.7) from age 5 to 12 years and unrelated to allergy trajectory. Lung function and allergic sensitization were associated with wheezing episodes in an additive fashion. In children with asthma, measuring lung function at age 5 years added little to the medical history for predicting future wheezing episodes through age 12 years.

CONCLUSIONS

In high-risk urban children, age-related trajectories of allergic sensitization were not associated with lung function development; however, both indicators were related to continued wheezing. These results underscore the importance of understanding early-life factors that negatively affect lung development and suggest that treating allergic sensitization may not alter lung function development in early to mid-childhood.

Respiratory function after 30+ years following sulfur mustard exposure in survivors in Sweden

Background

Sulfur mustard (SM) exposure causes acute and chronic respiratory diseases. The extent of small airway dysfunction (SAD) in individuals exposed to SM is unclear. This study evaluated and compared SAD in SM-exposed and SM-unexposed participants using noninvasive lung function tests assessing small airway function.

Methods

This retrospective cohort study involved SM-exposed (n = 15, mean age: 53 ± 8 years) and SM-unexposed (n = 15, mean age: 53 ± 7 years) Kurdish-Swedish individuals in Sweden. Small airway resistance and reactance were assessed using impulse oscillometry (IOS). Nitrogen (N2) multiple breath washout (MBW) was employed to assess lung ventilation heterogeneity. The gas-exchanging capacity of the lungs was assessed using the diffusing capacity of the lungs for the carbon monoxide (DLCO) test. Lung function outcomes were reported as absolute values and z-scores. Group comparisons were performed using the Mann-Whitney U test.

Results

No statistically significant differences in age, height, or body mass index were observed between the two groups. IOS showed significantly increased small airway resistance, while N2MBW exhibited significantly increased global and acinar ventilation heterogeneity in SM-exposed individuals compared to that in unexposed individuals. SAD was identified in 14 of 15 SM-exposed individuals, defined as at least one abnormal IOS difference between resistance at 5 and 20 Hz (R5-R20) and/or area of reactance (AX) or N2MBW lung's acinar zone (Sacin), and DLCO adjusted to the alveolar volume (DLCO/VA) outcome. Of these 14 individuals, only 5 demonstrated concordant findings across the IOS and N2MBW tests.

Conclusion

Exposure to SM was positively associated with long-term impairment of respiratory tract function in the small airways in the majority of the previously SM-exposed individuals in the present study. Furthermore, both IOS and N2MBW should be employed to detect SAD in SM-exposed survivors as they provide complementary information. Identifying and characterizing the remaining pathology of the small airways in survivors of SM exposure is a first step toward improved treatment and follow-up.

Impulse oscillometry assessment of respiratory function in pediatric patients with a history of COVID-19

OBJECTIVE

While coronavirus disease 2019 (COVID-19) is generally considered to exhibit a less severe clinical course in children than in adults, studies have demonstrated that respiratory symptoms can endure for more than 3 months following infection in at least one-third of pediatric cases. The present study evaluates the respiratory functions of children aged 3-15 years within 3-6 months of their recovery from COVID-19 using impulse oscillometry (IOS) and compares them with the values of healthy children.

METHODS

Included in this prospective cross-sectional study were 63 patients (patient group) aged 3-15 years who contracted COVID-19 between December 2021 and May 2022, as well as 57 healthy children as a control group, matched for age and sex. The demographic, clinical, and laboratory data of the patients were recorded, and respiratory function was assessed based on airway resistance (zR5, zR20, R5-20) and reactance (zX5, zX20, reactance area [AX], resonant frequency [Fres]) using an IOS device.

RESULTS

There were no significant differences in the age, weight, height, and body weight z score values of the two groups (p > .05). While the zR5 and R5-20 levels of the patient group were higher (p = .008 and p < .001, respectively) than those of the controls, the zR20, AX, and Fres values did not differ significantly between the groups (p > .05). The parameters indicating the reactance, including zX5 and zX20, were significantly lower in the patient group than in the control group (p = .028 and p < .001, respectively).

CONCLUSION

Total and peripheral airway resistances were found to be elevated in children who had recovered from COVID-19 in the preceding 3-6 months.

Impulse Oscillometry as an Alternative Lung Function Test for Hospitalized Adults

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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]

BACKGROUND

Impulse oscillometry (IOS) is an effort independent method of studying lung mechanics.

AIM

To study the diagnostic significance of IOS in assessing lung mechanics after COVID-19.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Diagnostic accuracy of peripheral lung function measurements in paediatric asthma control assessment: a pilot study

Introduction

Recent studies have indicated the significance of the peripheral airways in asthma control. Methods estimating airway resistance, air trapping, and ventilation inhomogeneity are useful for assessing this area of the lung and have proven utility in the evaluation of asthma; however, it is unclear which method is most effective at characterising uncontrolled asthma.

Aim

To evaluate the diagnostic accuracy of various peripheral airway function measurements in the assessment of asthma control in children.

Material and methods

Children with controlled (n = 35) and uncontrolled (n = 29) asthma performed a sequence of pulmonary function tests (i.e. spirometry, body plethysmography, oscillometry, nitrogen washout test, and exhaled nitric oxide). The diagnostic accuracy of each peripheral airway measure was evaluated by an area under the receiver operating characteristic curve (AUC).

Results

Most peripheral airway parameters were significantly increased in children with uncontrolled asthma compared with children with controlled asthma. The measures with the highest diagnostic accuracy for asthma control were lung clearance index (LCI) (AUC = 0.76), with high specificity (0.97) and modest sensitivity (0.46), acinar ventilation heterogeneity (Sacin) (AUC = 0.73), with high sensitivity (0.85) and modest specificity (0.54), and resonance frequency (Fres) (AUC= 0.74), with perfect specificity (1.0) but low sensitivity (0.38).

Conclusions

LCI, Sacin and Fres had the highest discriminative capacity for distinguishing children with controlled and uncontrolled asthma among all evaluated peripheral airways measures. Discrepancies in the performance (i.e. sensitivity and specificity) of each parameter suggest that a combination may be most effective in determining asthma control status.

The long-term impact of COVID-19 pneumonia on pulmonary function and exercise capacity

Background

The sequelae of post-coronavirus disease 2019 (COVID-19) have been widely reported. However, the time point of the follow-up time in the previous studies varied ranging from 3-24 months and the interval time of the follow-up time was too long (6 or 12 months). Thus, a shorter interval time during recovery for assessment of the sequelae of post COVID-19 on lung function and exercise capacity is still required. Therefore, this study aims to explore the long-term impact of COVID-19 pneumonia on pulmonary function and exercise capacity.

Methods

A prospective observational study was conducted on post COVID-19 pneumonia at the Lung Health Center, Division of Pulmonary, Critical Care and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand between May 2021 and April 2022. Spirometry, impulse oscillometry (IOS), and fractional exhaled nitric oxide (FeNO) were assessed at 1-, 6-, 9-, and 12-month post-hospital discharge when compared to healthy controls. The six-minute walk test (6-MWT) was also assessed.

Results

Thirty-eight post COVID-19 pneumonia with ages 41.1±14.8 years (52.6% male) and twenty-five healthy controls were enrolled. The %predicted of forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) were significantly lower in post COVID-19 pneumonia compared to healthy controls at month 1 and month 9. The improvement of %predicted FVC and FEV1 was observed in post COVID-19 pneumonia. The six-minute walk distance (6-MWD) was significantly lower in post COVID-19 pneumonia compared to healthy controls in all visits, while the 6-MWD improved overtime in post COVID-19 pneumonia.

Conclusions

The long term sequelae of post COVID-19 pneumonia on lung function and exercise capacity were observed. Pulmonary function tests and six-minutes walk test are useful tools for detection of long term sequelae of post COVID-19 pneumonia.

Pulmonary outcomes of congenital diaphragmatic hernia patients based on defect size (CDH Study Group Stage)

Background

Congenital diaphragmatic hernia (CDH) is associated with significant pulmonary morbidity. Previous investigation has shown that postnatal inpatient morbidity is linked to diaphragmatic defect size. The objective of this study was to evaluate long-term pulmonary outcomes by CDH study group defect size.

Methods

A retrospective analysis was conducted for CDH patients (n=133) managed in a neonatal intensive care unit (NICU) at a single children's hospital within an adult hospital system and subsequently followed up at a comprehensive multidisciplinary CDH clinic (n=102) from January 2012 to April 2022. CDH patients were stratified according to Congenital Diaphragmatic Hernia Study Group (CDHSG) Stage, and then categorized as low-risk (LR), defect size A and B, or high-risk (HR), defect size C and D. Inpatient data, including the presence of pulmonary hypertension, extracorporeal life support (ECLS) utilization, and mechanical ventilation days, were collected. Post-discharge data including the prevalence of asthma, pulmonary hypertension, emergency department visits, the total number of hospitalizations, and average rehospitalization days were collected. Frequentist analysis was used.

Results

The outcomes for 133 NICU patients were analyzed (HR: n=54, LR: n=79). During NICU stay, the prevalence of pulmonary hypertension [HR: 16/54 (30%) vs. LR: 9/79 (12%), P=0.009], ECLS utilization [HR: 19/54 (35%) vs. LR: 4/79 (5%), P<0.001], and the average number of mechanical ventilation days [HR: 17 days (IQR: 12-27) vs. LR: 5 days (IQR: 2-9), P<0.001] were significantly higher in the HR CDH group. Post NICU discharge, the prevalence of asthma [HR: 20/54 (37%), vs. LR: 17/79 (22%), P=0.050)] and the total days of rehospitalization [HR: 9 (IQR: 2-27) vs. LR: 4 (IQR: 1-8), P=0.035] were significantly higher in HR group. Of the patients seen in the comprehensive multidisciplinary CDH clinic, obstructive lung disease measured by impulse oscillometry was increased in the HR CDH population compared to the reference group [median R5Hz was 12.95 kPa/(L/s) in CDH vs. 9.8 kPa/(L/s) (P=0.010)].

Conclusions

HR CDHSG Stage is associated with worse inpatient and long-term pulmonary outcomes.

Pulmonary Function Tests in the Evaluation of Early Lung Disease in Cystic Fibrosis

BACKGROUND

Properly evaluating respiratory system dysfunction is essential in children with cystic fibrosis (CF). This prospective study aimed to assess the course of early lung disease based on multiple breath nitrogen washout (MBNW), impulse oscillometry (IOS), and conventional techniques, such as spirometry and body plethysmography.

METHODS

Over a 2 year recruitment period, subjects with CF aged 7-18 performed pulmonary function tests (PFTs). Moreover, the nutritional and microbiological status, frequency of pulmonary exacerbations (PExs), and patients' health-related quality of life (HRQoL) were assessed.

RESULTS

The mean age of the children (n = 69) was 14.09 ± 3.26 years; F/M 37/32. Spirometry-based diagnoses of normal lung function (forced expiratory volume in 1 s, FEV₁ ≥ 90%pred), mild (FEV₁ 70-89%pred) and moderate (FEV₁ 40-69%pred) lung diseases were established in 34 (49.3%), 25 (36.2%), and 10 (14.5%) patients, respectively. An elevated lung clearance index (LCI > 6.98) was observed in 85% of the subjects with normal FEV₁. The presence of Pseudomonas aeruginosa infection (n = 16) and the number of PExs treated with IV antibiotics were associated with significantly worse PFT results.

CONCLUSIONS

MBNW and IOS are more helpful tools than conventional techniques in assessing early lung disease in CF. LCI is a more useful parameter for detecting functional abnormalities than FEV₁ in school-age children.

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

Background

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.

Methods

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.

Results

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), FEF_25-75, L (12-week p = 0.023, 24-week p = 0.002), and FEF_25-75% 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.

Conclusion

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.

D-ROMs and PAT Tests Reveal a High Level of Oxidative Stress in Patients with Severe Well-Controlled Asthma, and D-ROMs Are Positively Correlated with R20 Values That Indicate Approximate Central Airway Resistance

BACKGROUND

The derivatives-reactive oxygen metabolites (d-ROMs) and plasma antioxidant capacity (PAT) tests are oxidative indexes. Severe asthma has been related to oxidative stress. We aimed to investigate d-ROMs and PAT values in severely controlled asthmatics and the correlation of these values with lung function.

METHODS

Blood samples were collected from severely controlled asthmatics and centrifuged at 3000 rpm for 10 min. The supernatant was collected. The assays were performed within three hours of collection. The fraction of exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and spirometry were determined. Symptom control was recorded using the asthma control test (ACT).

RESULTS

Approximately 40 patients with severe controlled asthma (75%: women), mean age of 62 ± 12 years, were recruited. Approximately 5% had obstructive spirometry. The IOS revealed airway abnormalities even though the spirometric results were within the normal range, with it being more sensitive than spirometry. The D-ROMs and PAT test values were higher than normal, indicating oxidative stress in severe asthmatics with controlled asthma. D-ROMs were positively correlated with R20 values, indicating central airway resistance.

CONCLUSIONS

The IOS technique revealed an otherwise hidden airway obstruction with spirometry. The D-ROMs and PAT tests revealed a high level of oxidative stress in severe controlled asthmatics. D-ROMs correlate with R20, indicating central airway resistance.

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

Background

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).

Design

This is a cross-sectional study.

Methods

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.

Results

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).

Conclusion

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.

Exercise-induced bronchoconstriction is associated with air humidity and particulate matter concentration in preschool children

BACKGROUND

Long-term exposure to air pollution is connected to asthma morbidity in children. Exercise-induced bronchoconstriction (EIB) is common in asthma, and the free running test outdoors is an important method for diagnosing asthma in children. It is not known whether momentary air pollution exposure affects the results of outdoor exercise tests in children.

METHODS

We analyzed all reliable exercise challenge tests with impulse oscillometry in children (n = 868) performed between January 2012 and April 2015 at Tampere University Hospital. Pollutant concentrations (PM_2.5 , NO₂ , and O₃ ) at the time of the exercise test were collected from public registers. We compared the pollutant concentrations with the proportion and severity of EIB and adjusted the analyses for air humidity and pollen counts.

RESULTS

Pollution levels were rarely high (median PM_2.5 6.0 µg/m³ , NO₂ 12.0 µg/m³ , and O₃ 47.0 µg/m³ ). The relative change in resistance at 5 Hz after exercise did not correlate with O₃ , NO₂ or PM_2.5 concentrations (p values 0.065-0.884). In multivariate logistic regression, we compared the effects of PM_2.5 over 10 µg/m³, absolute humidity (AH) over 10 g/m³ and alder or birch pollen concentration over 10 grains/m³. High (over 10 g/m³ ) AH was associated with decreased incidence (OR 0.31, p value 0.004), and PM_2.5 over 10 µg/m³ was associated with increased incidence (OR 1.69, p value 0.036) of EIB.

CONCLUSIONS

Even low PM_2.5 levels may have an effect on EIB in children. Of the other properties of air, only AH was associated with the incidence of EIB.

Effect of Obesity on Airway Mechanics

Background

Obesity is known to induce lung function impairment. Previous studies of decline in lung function associated with obesity are well established.

Materials and Methods

In this cross-sectional study, to evaluate the effects of different obesity indices on lung mechanics, healthy subjects (males-23 and females-22) were recruited. Anthropometric parameters like body mass index (BMI), waist circumference (WC), hip circumference (HC) and neck circumference (NC) were measured and waist-hip ratio (WHR) was derived. Spirometry, impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) measurements were performed to assess lung function. Subgroups were divided and analysed.

Results

In males, increased WHR is associated with increased total airway resistance (R5). BMI correlates positively with R5, R5% predicted, resistance at 20 Hz (R20) and R20% predicted; likewise, WHR shows a positive correlation with R5. In females, increased WHR has significantly higher R5, R5% predicted, R20, R20% predicted, area of reactance (Ax), resonant frequency (Fres) and decreased reactance at 5 Hz (X5), reactance at 20 Hz (X20), X20% predicted. The female group with higher WC shows significantly increased R5, R5% predicted, R20, R20% predicted, Ax, Fres and lower fixed ratio of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC), X5, X20, X20% predicted. The group with higher NC has a lower FEV1/FVC ratio. WHR positively correlated with R5% predicted and Fres while WC correlated positively with R5, R5% predicted, Ax and Fres; same way, NC with X5% predicted.

Conclusion

Obesity/overweight causes significant changes in lung volumes, capacity and airway mechanics, Higher WC and WHR are associated with significant changes in lung mechanics, which are more prominent in females than in males. NC is not associated with changes in lung mechanics.

Impulse Oscillometry as a Diagnostic Test for Pulmonary Emphysema in a Clinical Setting

Body plethysmography (BP) is the standard pulmonary function test (PFT) in pulmonary emphysema diagnosis, but not all patients can cooperate to this procedure. An alternative PFT, impulse oscillometry (IOS), has not been investigated in emphysema diagnosis. We investigated the diagnostic accuracy of IOS in the diagnosis of emphysema. Eighty-eight patients from the pulmonary outpatient clinic at Lillebaelt Hospital, Vejle, Denmark, were included in this cross-sectional study. A BP and an IOS were performed in all patients. Computed tomography scan verified presence of emphysema in 20 patients. The diagnostic accuracy of BP and IOS for emphysema was evaluated with two multivariable logistic regression models: Model 1 (BP variables) and Model 2 (IOS variables). Model 1 had a cross-validated area under the ROC curve (CV-AUC) = 0.892 (95% CI: 0.654-0.943), a positive predictive value (PPV) = 59.3%, and a negative predictive value (NPV) = 95.0%. Model 2 had a CV-AUC = 0.839 (95% CI: 0.688-0.931), a PPV = 55.2%, and an NPV = 93.7%. We found no statistically significant difference between the AUC of the two models. IOS is quick and easy to perform, and it can be used as a reliable rule-out method for emphysema.

Maternal vitamin D status modifies the effects of early life tobacco exposure on child lung function

BACKGROUND

Prior studies suggest that vitamin D may modify the effects of environmental exposures; however, none have investigated gestational vitamin D and cumulative tobacco smoke exposure (TSE) throughout pregnancy and early life.

OBJECTIVES

This study investigated the effects of early life TSE on child lung function and the modulatory effects of gestational vitamin D on this association.

METHODS

The VDAART (Vitamin D Antenatal Asthma Reduction Trial) recruited nonsmoking pregnant women and followed the mother-child pairs to age 6 years. TSE was assessed with questionnaires and plasma cotinine measurements in the mothers (10-18 and 32-38 gestational weeks) and children (1, 3, and 6 years). Cumulative TSE was calculated from the repeated cotinine measurements. 25-hydroxyvitamin D (25[OH]D) levels were measured at 10-18 and 32-38 gestational weeks. Lung function was assessed at 6 years with spirometry and impulse oscillometry.

RESULTS

Of the 476 mother-child pairs, 205 (43%) had increased cotinine levels at ≥1 time point. Cumulative TSE was associated with decreased FEV1 (β = -0.043 L, P = .018) and increased respiratory resistance at 5 Hz (R5; β = 0.060 kPa/L/s, P = .002). This association persisted in subjects with insufficient (<30 ng/mL) 25(OH)D levels throughout pregnancy (β = 0.077 kPa/L/s, P = .016 for R5) but not among those with sufficient levels throughout pregnancy.

CONCLUSIONS

Cumulative TSE from pregnancy to childhood is associated with dose- and duration-dependent decreases in child lung function at 6 years even in the absence of reported maternal smoking. Gestational vitamin D may modulate this effect and have therapeutic potential for minimizing the adverse effect of TSE on lung throughout early life.

RANDOMIZED TRIAL

Maternal Vitamin D Supplementation to Prevent Childhood Asthma (VDAART); clinicaltrials.gov identifier: NCT00920621.

Quantitative CT Metrics for the Prediction of Therapeutic Effect in Asthma

Background: Few studies have explored the correlation between asthma medication and features on HRCT images. We aim to analyse the differences and temporal changes of lung function and airway resistance in asthma with diverse HRCT phenotypes in a short period after inhalation of budesonide/formoterol. Method: This observational study recruited 55 adult patients with varying severities of asthma. We performed detailed airway metrics measurements of chest CT scans, such as airway wall thickness (WT), wall area percentage (WA%), wall thickness percentage (T/OR), and airways with an inner perimeter of 10 mm (Pi10). The effect of lung structural features on asthma medication response was explored according to the WA% and T/OR twelve hours post-drug administration. Using multivariable regression models, we then assessed the influence of WA% on lung function. Results: WA% (p < 0.001) and T/OR (p < 0.001) significantly increased in asthma than in healthy control subjects. Compared to mild asthma, airway walls were further thickened (WA%, p = 0.023; T/OR: p = 0.029) and associated with lumen narrowing (Pi10, p = 0.055) in moderate to severe asthma. WA% and T/OR correlated well with lung function (FEV1, FVC, MMEF, and PEF) and airway resistance (R5, R20, Rp, and Fres). Regression analysis showed that MEF25 decreased with increasing age and WA% (R2 = 0.58, p < 0.001). Patients with thickened airway walls experienced a maximal increase in FVC, FEV1, and PEF at 2 h (p < 0.001) and a maximal decrease of R5, Z5, and Rp at 2 h (p < 0.001) in those with a thickened airway pattern. Conclusions: Asthma patients with different bronchial wall thicknesses exhibited variable lung function changes. Specifically, patients with thick airway wall patterns were more sensitive to inhaled budesonide in the short term.

Corrigendum: Discordant spirometry and impulse oscillometry assessments in the diagnosis of small airway dysfunction

[This corrects the article DOI: 10.3389/fphys.2022.892448.].

Role of impulse oscillometry in diagnosis and follow-up in bronchial asthma

Background

Asthma is defined as a chronic inflammatory disorder of the airways, characterized by bronchial hyper-responsiveness and variable airflow obstruction, that is often reversible either spontaneously or with treatment. Impulse oscillometry is a newer diagnostic modality for asthma. It is based on the measurement of sound waves reflected by airway resistance.

Objectives

The aim of this article is to study the role of impulse oscillometry in diagnosis and follow-up of bronchial asthma.

Methods

Fifty-five clinically diagnosed bronchial asthma patients were evaluated with spirometry and impulse oscillometry before and after 3 months of inhaled treatment. The sensitivity to diagnose and follow-up was compared using proper statistical tests.

Results

Impulse oscillometry was superior to spirometry in diagnosing bronchial asthma and also in accessing the treatment response after 3 months.

Conclusion

Impulse oscillometry is superior in predicting bronchial asthma and its parameters are also more sensitive in accessing treatment response. It can replace spirometry as it is easy to perform and effort independent.

Pulmonary function in children with persistent tachypnea of infancy

BACKGROUND

Data on the prevalence and type of lung function impairment in preschool and school-aged children previously diagnosed with persistent tachypnea of infancy (PTI) are scarce. Therefore, this study aims to assess pulmonary function in this age group.

METHODS

Children diagnosed with PTI over 3 years old were admitted for follow-up visits and healthy controls were enrolled. The study group included children who were able to complete pulmonary function tests (PFTs). Medical history, physical examination, and pulmonary function (spirometry, body plethysmography, impulse oscillometry, nitrogen multiple breath washout test, diffusing capacity for carbon monoxide [DL_CO ]) were assessed.

RESULTS

Thirty-seven children (26 boys, 11 girls; median age: 5.6 years) diagnosed with PTI and 37 healthy controls were recruited. Forced expiratory volume in 1 s and forced vital capacity were significantly lower (-1.12 vs. 0.48, p = 0.002 and -0.83 vs. 0.31, p = 0.009, respectively); respiratory resistance at 5 Hz (0.06 vs. -0.62, p = 0.003), resonant frequency (1.86 vs. 1.36, p = 0.04), residual volume (RV) (2.34 vs. -1.2, p < 0.0001), RV%TLC (total lung capacity) (2.63 vs. -0.72, p < 0.0001), and specific airway resistance (5.4 vs. 2.59, p = 0.04) were significantly higher in PTI patients as compared with controls (data were presented as median z-score). Air trapping was found in 60.0%, and abnormally high lung clearance index and DL_CO  were found in 73.3% and 90.9% of PTI patients, respectively.

CONCLUSIONS

This study demonstrated that lung function is affected in most children with PTI. PFTs showed that peripheral airways are the major zone of functional impairment.

Airway morphological abnormalities of bronchiolitis assessed by endobronchial optical coherence tomography

BACKGROUND

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.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Comparison between impulse oscillometry parameters and spirometry for the diagnosis of exercise-induced bronchoconstriction in asthmatic children and adolescents

INTRODUCTION

Impulse oscillometry (IOS) parameters are obtained more easily and effortlessly in comparison to forced expiratory volume in the first second (FEV1).

OBJECTIVE

To compare IOS parameters to FEV1 in exercise-induced bronchoconstriction (EIB) diagnosis.

METHODS

Seventy-four (60.8% male; 39.2 female) young asthmatics aged between 7 and 17 years (mean 12.6 ± 2.8 years) were evaluated. EIB was defined as a reduction in FEV1 ≥ 10% compared with basal after standardized challenge by treadmill running (TR). IOS parameters and FEV1 were obtained at baseline and 5,15, and 30 min after TR. The area under the receiver operator characteristic curve (AUC) was calculated from the reduction in FEV1 ≥ 10% to evaluate the best psychometric characteristics of IOS parameters.

RESULTS

Twenty-four individuals (32.4%) were diagnosed with EIB. A moderate inverse correlation was found between the IOS and FEV1 variables immediately after the TR, with resistance at 5 Hz (R5Hz), resonant frequency (Fres), and reactance area (AX), (r = -0.64, r = -0.53 and r = -0.69, respectively, all with p < 0.05). An increase of 25 kPa/l/s in R5 Hz, of 19k Pa/l/s in AX and 21 Hz in Fres were found to best correlate with EIB diagnosis by FEV1 (sensitivity 67% and specificity 62%, sensitivity 84% and specificity 50%, and sensitivity 84% and specificity 60%, respectively).

CONCLUSION

IOS parameters have a significant inverse correlation with FEV1. This study presents cut-off points for EIB diagnosis for R5Hz, AX, and Fres, however, the findings in IOS parameters should be used and interpreted carefully if the goal is to replace spirometry.

Poor early childhood growth is associated with impaired lung function: Evidence from a Ghanaian pregnancy cohort

OBJECTIVES

Nearly 40% of African children under 5 are stunted. We leveraged the Ghana randomized air pollution and health study (GRAPHS) cohort to examine whether poorer growth was associated with worse childhood lung function.

STUDY DESIGN

GRAPHS measured infant weight and length at birth and 3, 6, 9,12 months, and 4 years of age. At age 4 years, n = 567 children performed impulse oscillometry. We employed multivariable linear regression to estimate associations between birth and age 4 years anthropometry and lung function. Next, we employed latent class growth analysis (LCGA) to generate growth trajectories through age 4 years. We employed linear regression to examine associations between growth trajectory assignment and lung function.

RESULTS

Birth weight and age 4 weight-for-age and height-for-age z-scores were inversely associated with airway resistance (e.g., R5 , or total airway resistance: birth weight β = -0.90 cmH2O/L/s, 95% confidence interval [CI]: -1.64, -0.16 per 1 kg increase; and R20 , or large airway resistance: age 4 height-for-age β = -0.40 cmH2O/L/s, 95% CI: -0.57, -0.22 per 1 unit z-score increase). Impaired growth trajectories identified through LCGA were associated with higher airway resistance, even after adjusting for age 4 body mass index. For example, children assigned to a persistently stunted trajectory had higher R5 (β = 2.71 cmH2O/L/s, 95% CI: 1.07, 4.34) and R20 (β = 1.43 cmH2O/L/s, 95% CI: 0.51, 2.36) as compared to normal.

CONCLUSION

Children with poorer anthropometrics through to age 4 years had higher airway resistance in early childhood. These findings have implications for lifelong lung health, including pneumonia risk in childhood and reduced maximally attainable lung function in adulthood.

Decrements in lung function and respiratory abnormalities associated with exposure to diacetyl and 2,3-pentanedione in coffee production workers

Coffee production workers are exposed to complex mixtures of gases, dust, and vapors, including the known respiratory toxins, diacetyl, and 2,3-pentanedione, which occur naturally during coffee roasting and are also present in flavorings used to flavor coffee. This study evaluated the associations of these two α-diketones with lung function measures in coffee production workers. Workers completed questionnaires, and their lung function was assessed by spirometry and impulse oscillometry (IOS). Personal exposures to diacetyl, 2,3-pentanedione, and their sum (Sum_DA+PD) were assigned to participants, and metrics of the highest 95th percentile (P95), cumulative, and average exposure were calculated. Linear and logistic regression models for continuous and binary/polytomous outcomes, respectively, were used to explore exposure-response relationships adjusting for age, body mass index, tenure, height, sex, smoking status, race, or allergic status. Decrements in percent predicted forced expiratory volume in 1 second (ppFEV₁) and forced vital capacity (ppFVC) were associated with the highest-P95 exposures to 2,3-pentanedione and Sum_DA+PD. Among flavoring workers, larger decrements in ppFEV₁ and ppFVC were associated with highest-P95 exposures to diacetyl, 2,3-pentanedione, and Sum_DA+PD. Abnormal FEV₁, FVC, and restrictive spirometric patterns were associated with the highest-P95, cumulative, and average exposures for all α-diketone metrics; some of these associations were also present among flavoring and non-flavoring workers. The combined category of small and peripheral airways plus small and large airways abnormalities on IOS had elevated odds for highest-P95 exposure to α-diketones. These results may be affected by the small sample size, few cases of abnormal spirometry, and the healthy worker effect. Associations between lung function abnormalities and exposure to α-diketones suggest it may be prudent to consider exposure controls in both flavoring and non-flavoring settings.

Discordant Spirometry and Impulse Oscillometry Assessments in the Diagnosis of Small Airway Dysfunction

Background and objective: Spirometry is commonly used to assess small airway dysfunction (SAD). Impulse oscillometry (IOS) can complement spirometry. However, discordant spirometry and IOS in the diagnosis of SAD were not uncommon. We examined the association between spirometry and IOS within a large cohort of subjects to identify variables that may explain discordant spirometry and IOS findings. Methods: 1,836 subjects from the ECOPD cohort underwent questionnaires, symptom scores, spirometry, and IOS, and 1,318 subjects were examined by CT. We assessed SAD with R₅-R₂₀ > the upper limit of normal (ULN) by IOS and two of the three spirometry indexes (maximal mid-expiratory flow (MMEF), forced expiratory flow (FEF)_50%, and FEF_75%) < 65% predicted. Multivariate regression analysis was used to analyze factors associated with SAD diagnosed by only spirometry but not IOS (spirometry-only SAD) and only IOS but not spirometry (IOS-only SAD), and line regression was used to assess CT imaging differences. Results: There was a slight agreement between spirometry and IOS in the diagnosis of SAD (kappa 0.322, p < 0.001). Smoking status, phlegm, drug treatment, and family history of respiratory disease were factors leading to spirometry-only SAD. Spirometry-only SAD had more severe emphysema and gas-trapping than IOS-only SAD in abnormal lung function. However, in normal lung function subjects, there was no statistical difference in emphysema and gas-trapping between discordant groups. The number of IOS-only SAD was nearly twice than that of spirometry. Conclusion: IOS may be more sensitive than spirometry in the diagnosis of SAD in normal lung function subjects. But in patients with abnormal lung function, spirometry may be more sensitive than IOS to detect SAD patients with clinical symptoms and CT lesions.

Predictive value of impulse oscillometry and multiple breath washout parameters in pediatric patients with cystic fibrosis pulmonary exacerbation

BACKGROUND

Pulmonary exacerbations (PE) tend to complicate the course of cystic fibrosis (CF) and worsen the disease prognosis. One of the diagnostic criteria for an exacerbation is the forced expiratory volume in the first second (FEV₁ ) decline. Not all children, however, are able to perform spirometry. Therefore, the aim of this study was to evaluate alternative lung function tests in the diagnosis of PE.

METHODS

We assessed retrospectively the results of impulse oscillometry (IOS) and lung clearance index in multiple breath washout (MBW) during 259 visits in 47 CF paediatric patients. The differences in the results were compared between patients diagnosed with PE (ΔPE) and those in stable condition (ΔS).

RESULTS

Among the whole group of patients, we found significant differences between the changes during exacerbation (ΔPEs) and stable condition (ΔSs) values for lung clearance index (LCI), S_acin , R5Hz, R5-20Hz, X10Hz, AX, and Fres. The predictive values of Fres and X10Hz in IOS (AUC^ROC 0.71 both parameters) were higher than those of LCI (AUC^ROC 0.67). There was no difference in the predictive values (AUC^ROC ) of Δ LCI and IOS parameters in the subgroups of patients stratified based on FEV₁ z-score cut-off value of -1.64. In both groups of patients, predictive values of LCI were slightly lower than of IOS parameters (AUC 0.66 for LCI vs. 0.69 for both ΔX10Hz z-score and Δ Fres z-score in patients with FEV₁ z-score ≥-1.64 and AUC 0.67 for LCI vs 0.69 for both ΔX10Hz zscore and Δ Fres zscore in patients with FEV₁ <1.64.

CONCLUSIONS

Both IOS and MBW measurements are useful in the assessment of pediatric CF patients with PE. LCI has a similar predictive value to IOS in children with CF independently of their FEV₁ value.

The Role of Impulse Oscillometry in Evaluating Disease Severity and Predicting the Airway Reversibility in Patients With Bronchiectasis

Background

Impulse oscillometry (IOS) can be used to evaluate airway impedance in patients with obstructive airway diseases. Previous studies have demonstrated that IOS parameters differ between patients with bronchiectasis and healthy controls. This study aims to explore the usefulness of IOS in assessing disease severity and airway reversibility in patients with bronchiectasis.

Method

Seventy-four patients with non-cystic fibrosis bronchiectasis who visited our Respiratory Medicine outpatient clinic were consecutively recruited. Spirometry, plethysmography and IOS tests were performed. Patients were stratified into mild, moderate and severe disease according to Reiff, Bhalla, BSI, FACED, and BRICS scores. Airway reversibility was measured by bronchodilation test (BDT) and the result was classified as positive or negative. ROC curves of IOS parameters were used to assess the usefulness of IOS parameters in predicting airway reversibility. Correlations between the IOS, spirometric lung function and bronchiectasis severity parameters were analyzed.

Results

Many IOS parameters, such as airway resistance at 5 Hz (R5), small airways resistance (R5-R20), total airway reactance (X5), resonance frequency (Fres), total airway impedance at 5 Hz (Z5), and peripheral resistance (Rp) increased in patients with bronchiectasis who presented a moderate to severe severity as categorized by the FACED, BSI and Reiff scores. Large airway resistance (R20) and central resistance (Rc) were not significantly different among groups with different bronchiectasis severity. The difference between R5 and R20 (R5-R20) showed 81.0% sensitivity, and 69.8%specificity in predicting the airway reversibility in bronchiectasis with AUC of 0.794 (95%CI, 0.672-0.915).

Conclusion

IOS measurements are useful indicators of bronchiectasis severity and may be useful for predicting the airway reversibility.

Small Airway Dysfunction Measured by Impulse Oscillometry and Fractional Exhaled Nitric Oxide Is Associated With Asthma Control in Children

BACKGROUND

Impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) are sensitive and non-invasive methods to measure airway resistance and inflammation, although there are limited population-based studies using IOS and FeNO to predict asthma control.

OBJECTIVE

This study aimed to investigate the utility of IOS and FeNO for assessing childhood asthma control in terms of small airway dysfunction and airway inflammation.

METHODS

This prospective observational cohort study enrolled 5,018 school children (aged 6-12 years), including 560 asthmatic children and 140 normal participants. FeNO, spirometry, IOS, bronchial dilation test, total IgE, and childhood asthma control test (C-ACT) were measured. FeNO, IOS, spirometry, and C-ACT results were correlated with childhood asthma with and without control.

RESULTS

Uncontrolled asthmatic children had abnormal FeNO, IOS, and spirometric values compared with control subjects (P < 0.05). IOS parameters with R5, R5-R20, X5, Ax, △R5, and FeNO can predict lower C-ACT scales by the areas under receiver operating characteristic curves (AUCs) (0.616, 0.625, 0.609, 0.622, 0.625, and 0.714). A combination of FeNO (>20 ppb) with IOS measure significantly increased the specificity for predicting uncontrolled asthma patients compared with FeNO alone (P < 0.01). A multiple regression model showed that small airway parameter (R5-R20) was the strongest risk factor [OR (95% CI): 87.26 (7.67-993.31)] for uncontrolled asthma patients. Poor control with lower C-ACT scales correlated with high FeNO (r = -0.394), R5 (r = -0.106), and R5-R20 (r = -0.129) in asthmatic children (P < 0.05).

CONCLUSION

A combined use of FeNO and IOS measurements strongly predicts childhood asthma with or without control.

Small airway dysfunction is an independent dimension of wheezing disease in preschool children

BACKGROUND

Whether small airway dysfunction (SAD), which is prevalent in asthma, helps to characterize wheezing phenotypes is undetermined. The objective was to assess whether SAD parameters obtained from impedance measurement and asthma probability are linked.

METHODS

One hundred and thirty-nine preschool children (mean age 4.7 years, 68% boys) suffering from recurrent wheezing underwent impulse oscillometry that allowed calculating peripheral resistance and compliance of the respiratory system (markers of SAD) using the extended RIC model (central and peripheral resistance, inertance, and peripheral compliance). Children were classified using the probability-based approach of GINA guidelines (few, some, and most having asthma). A principal component analysis (PCA) that determined the dimensions of wheezing disease evaluated the links between SAD and asthma probability.

RESULTS

Forty-seven children belonged to the few, 28 to the some, and 64 to the most having asthma groups. Whereas their anthropometrics and measured parameters were similar, the most having asthma group exhibited the lowest mean value of airway inertance after bronchodilator probably due to airway inhomogeneities. PCA characterized four independent dimensions including a peripheral resistance (constituted by baseline peripheral compliance, Frs, R5Hz, R5-20Hz, X5Hz, and AX), a central resistance (baseline central resistance, R20Hz), anthropometrics (age and height), and asthma probability (wheezing patterns and therapeutic steps). Thus, PCA showed that the SAD markers were independent from clinical dimensions and were unable to differentiate wheezing phenotypes.

CONCLUSIONS

Lung function parameters obtained from impulse oscillometry and asthma probability were belonging to independent dimensions of the wheezing disease.

Within-Breath Oscillatory Mechanics in Horses Affected by Severe Equine Asthma in Exacerbation and in Remission of the Disease

Oscillometry is a technique that measures the resistance (R) and the reactance (X) of the respiratory system. In humans, analysis of inspiratory and expiratory R and X allows to identify the presence of tidal expiratory flow limitation (EFLt). The aim of this study was to describe inspiratory and expiratory R and X measured by impulse oscillometry system (IOS) in horses with severe asthma (SEA) when in clinical remission (n = 7) or in exacerbation (n = 7) of the condition. Seven healthy, age-matched control horses were also studied. Data at 3, 5, and 7 Hz with coherence > 0.85 at 3 Hz and >0.9 at 5 and 7 Hz were considered. The mean, inspiratory and expiratory R and X and the difference between inspiratory and expiratory X (ΔX) were calculated at each frequency. The data from the three groups were statistically compared. Results indicated that in horses during exacerbation of severe asthma, X during expiratory phase is more negative than during inspiration, such as in humans in presence of EFLt. The evaluation of X during inspiration is promising in discriminating between horses with SEA in remission and control horses.

Impulse Oscillometry Findings and Their Associations With Lung Ultrasound Signs in COVID-19 Survivors

BACKGROUND

Because impulse oscillometry (IOS) can detect changes in the small airways and is safer to perform during the COVID-19 pandemic than other pulmonary function tests, it may have value in investigating pulmonary sequelae in COVID-19 survivors. This study evaluated the performance of IOS in detecting lung abnormalities in COVID-19 survivors and investigated the associations of the findings with those of lung ultrasound (LUS) and spirometry.

METHODS

In this cross-sectional study, 117 subjects underwent IOS at a frequency range of 4-20 Hz 2 months after COVID-19 diagnosis. They also underwent spirometry and LUS, and their aeration scores were calculated.

RESULTS

On IOS, the resonance frequency was > 12 Hz, and the area under the reactance curve was > 3.60 cm H₂O/L/s in 70 (59.8%) and 55 (47.0%) subjects, respectively. A heterogeneity of resistance between R4 and R20 (R4-R20) > 20% was observed in 60 (51.3%) participants. Based on their abnormalities in resistive and reactive parameters, 76 (65.0%) participants had abnormal IOS. Spirometry abnormalities were detected in 40 (34.2%) cases. LUS was abnormal in 51 (43.6%) participants, and the median aeration score was 0 (0-8) points. Abnormal IOS was associated with abnormal LUS (P < .001) and abnormal spirometry (P = .002). Abnormal spirometry had a significant but weaker association with abnormal LUS (P = .031). In participants who reported hospitalization, abnormal IOS was associated with both abnormal LUS (P = .001) and abnormal spirometry (P = .006). In participants who did not report hospitalization, abnormal IOS was associated with abnormal LUS (P < .001) but not abnormal spirometry (P = .063).

CONCLUSIONS

In COVID-19 survivors, IOS detected changes even when spirometry was normal. In these individuals, IOS parameters were more strongly associated with abnormalities on LUS than with abnormalities on spirometry.

Peripheral airways involvement in children with asthma exacerbation

Objective

The literature provides some evidence of peripheral airways key role in the pathogenesis of asthma. However, the extent to which lung periphery including acinar zone contribute to asthma activity and control in pediatric population is unclear. Therefore, the aim of the study was to estimate peripheral airways involvement in children with asthma exacerbation and stable asthma simultaneously via different pulmonary function tests.

Methods

Children with asthma exacerbation (n = 20) and stable asthma (n = 22) performed spirometry, body plethysmography, exhaled nitric oxide, impulse oscillometry (IOS), and multiple‐breath washout (MBW).

Results

Peripheral airway's function indexes were increased in children with asthma, particularly in group with asthma exacerbation when compared with stable asthma group. The prevalence of abnormal results was significantly higher in asthma exacerbation. All children with asthma exacerbation had conductive ventilation inhomogeneity; 76% had acinar ventilation inhomogeneity. According to IOS measurements, resistance and reactance were within normal range, but other IOS parameters were significantly higher in children with asthma exacerbation compared with stable asthma group. The 36% of children with acute asthma had air trapping.

Conclusion

Significant involvement of peripheral airways was observed in children with asthma, particularly in asthma exacerbation, which determine lung periphery as important additional target for therapy and provide new insights into pathophysiological process of pediatric asthma.

Respiratory function in children with nephrotic syndrome: Comparative evaluation of impulse oscillometry and spirometry

AIM

To evaluate the respiratory functions of children with nephrotic syndrome (NS) by impulse oscillometry (IOS) and its correlation with spirometry.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

School-Age Obese Asthmatic Children have Distinct Lung Function Measures From Lean Asthmatics and Obese Children

Background: The lung functions of children with obese asthma seem to be distinct from those of obese children or lean asthmatics.Aim: To measure baseline lung function, exercise-induced bronchoconstriction (EIB), and bronchial hyperreactivity (BHR) in school-age obese asthmatics (OA group) and to compare the data with obese children (O group), lean asthmatics (A group), and healthy controls (H group).Methods: One hundred seventy school-age children were enrolled in this prospective cross-sectional study. Baseline fractionated exhaled nitric oxide (FeNO), and baseline, post-exercise (post-E), and post-bronchodilation (post-BD) impulse oscillometry (IOS) and spirometry tests were performed. EIB and BHR were evaluated based on the difference (Δ) in post-E - baseline, and post-BD - baseline values.Results: The mean FeNO level was higher in the OA group than in the other groups (p = 0.002). Baseline zR5 and R5-20 were higher (p = 0.013 and p = 0.044), but zFEF25-75 was lower (p < 0.01), in the OA group. ΔPost-E - baseline zFEV1 was lower in the A group (p = 0.003) but was higher in the OA group (p = 0.014) than the other groups. ΔPost-BD - baseline zFEV1 was lower in the H group compared to the other three groups (p = 0.004), but no significant difference was observed among the O, A, and OA groups (p > 0.05).Conclusion: A higher airway inflammation (high FeNO), peripheral airway resistance (high zR5 and zR5-20) and a lower peripheral airway flow (low FEF25-75) were observed at baseline measurement in school-age obese asthmatics compared to lean asthmatics and obese children. Obese asthmatics had no EIB but exhibited a similar BHR to that of asthmatics.

Infant Nasopharyngeal Microbiota Subphenotypes and Early Childhood Lung Function: Evidence from a Rural Ghanaian Pregnancy Cohort

Early life respiratory microbiota may increase risk for future pulmonary disease. Associations between respiratory microbiota and lung health in children from low- and middle-income countries are not well-described. Leveraging the Ghana Randomized Air Pollution and Health Study (GRAPHS) prospective pregnancy cohort in Kintampo, Ghana, we collected nasopharyngeal swabs in 112 asymptomatic children aged median 4.3 months (interquartile range (IQR) 2.9, 7.1) and analyzed 22 common bacterial and viral pathogens with MassTag polymerase chain reaction (PCR). We prospectively followed the cohort and measured lung function at age four years by impulse oscillometry. First, we employed latent class analysis (LCA) to identify nasopharyngeal microbiota (NPM) subphenotypes. Then, we used linear regression to analyze associations between subphenotype assignment and lung function. LCA suggest that a two-class model best described the infant NPM. We identified a higher diversity subphenotype (N = 38, 34%) with more pathogens (median 4; IQR 3.25, 4.75) and a lower diversity subphenotype (N = 74, 66%) with fewer pathogens (median 1; IQR 1, 2). In multivariable linear regression models, the less diverse NPM subphenotype had higher small airway resistance (R5-R20 β = 17.9%, 95% CI 35.6, 0.23; p = 0.047) compared with the more diverse subphenotype. Further studies are required to understand the role of the microbiota in future lung health.

The predictive value of impulse oscillometry for asthma exacerbations in childhood: A systematic review and meta-analyses

OBJECTIVE

Several studies have explored the predictive value of impulse oscillometry (IOS) for asthma exacerbations in childhood, but its specific parameters are still unclear. Therefore, we designed this meta-analysis to determine the related indicators of acute asthma attacks.

METHODS

A comprehensive literature search was performed on July 9, 2020 based on PubMed, Embase, and Web of Science database. Weighted mean differences (WMDs) were calculated using fixed- or random-effects models.

RESULTS

A total of 615 patients from six trials were included in this analysis. IOS may be a useful tool to predict asthma exacerbations. And the results showed that R5 (WMD = -1.21, 95% CI: -1.55 to -0.87, p < .001), Fres (WMD = -1.34, 95% CI: -2.03 to -0.65, p = .018), and AX (WMD = -7.35, 95% CI: -9.94 to -4.76, p < .001) had significant correlation with asthma exacerbations. In addition, X5 may also predict the acute attack of asthma (WMD = 0.81, 95% CI: 0.56 to 1.01, p < .001).

CONCLUSIONS

R5, AX, Fres, and X5 may be able to identify the risk of an acute attack of asthma. Besides, our research further demonstrated that peripheral airway injury may play an important role in the acute attack of asthma.

Small-Airway Function Variables in Spirometry, Fractional Exhaled Nitric Oxide, and Circulating Eosinophils Predicted Airway Hyperresponsiveness in Patients with Mild Asthma

Purpose

Patients with variable symptoms suggestive of asthma but with normal forced expiratory volume in 1 second (FEV₁) often fail to be diagnosed without a bronchial provocation test, but the test is expensive, time-consuming, risky, and not readily available in all clinical settings.

Patients and Methods

A cross-sectional study was performed in 692 patients with FEV₁≥80% predicted; normal neutrophils and chest high-resolution computed tomography; and recurrent dyspnea, cough, wheeze, and chest tightness.

Results

Compared with subjects negative for AHR (n=522), subjects positive for AHR (n=170) showed increased FENO values, peripheral eosinophils (EOS), and R5-R20; decreased FEV₁, FEV₁/Forced vital capacity (FVC), and forced expiratory flow (FEFs) (P≤.001 for all). Small-airway dysfunction was identified in 104 AHR⁺ patients (61.17%), and 132 AHR⁻ patients (25.29%) (P<0.001). The areas under the curve (AUCs) of variables used singly for an AHR diagnosis were lower than 0.77. Using joint models of FEF_50%, FEF_75%, or FEF_25%-75% with FENO increased the AUCs to 0.845, 0.824, and 0.844, respectively, significantly higher than univariate AUCs (P <0.001 for all). Patients who reported chest tightness (n=75) had lower FEFs than patients who did not (P<0.001 for all). In subjects with chest tightness, the combination of FEF_50% or FEF_25%-75% with EOS also increased the AUCs substantially, to 0.815 and 0.816, respectively (P <0.001 for all versus the univariate AUCs).

Conclusion

FENO combined with FEF_50% and FEF_25%-75% predict AHR in patients with normal FEV₁. FEF_25%-75%, FEF_50%, or FEF_25%-75% together with EOS also can potentially suggest asthma in patients with chest tightness.

Abnormal iron status is independently associated with reduced oscillometric lung function in schoolchildren

BACKGROUND

Associations between anemia and allergic diseases have been reported, but the relationship of iron deficiency with airway dysfunction in children remains unclear. We aimed to investigate the relationship between abnormal iron parameters and lung function in schoolchildren.

METHODS

Four hundred and forty-five children (10-12 years-old) from 11 elementary schools in were enrolled. The relationships of different iron parameters (hemoglobin, serum iron, transferrin saturation, and serum ferritin) with lung function evaluated by impulse oscillometry (airways resistance at 5 Hz [Rrs5], 10 Hz [Rrs10], and the difference of Rrs5 and Rrs20 Hz [Rrs5-20]), and with exhaled nitric oxide (FeNO) were evaluated after adjustment for confounders including height, sex, and body mass index z-score, and for additional covariates that could affect airway function.

RESULTS

Total airway dysfunction represented by Rrs5 was reduced in participants with low serum iron level (aβ: -0.13, 95% CI: -0.23 to -0.03, p = 0.040) after adjustment for key confounders, but did not correlate with other iron profiles. Reduced oscillometric lung function recorded as Rrs5-20 was related with low serum iron and high serum ferritin, but the results were inconsistent after multiple comparisons. Associations were not observed with serum hemoglobin.

CONCLUSIONS

Decreased serum iron level was related with airway dysfunction represented as oscillomteric Rrs5. Our results suggest a relationship of reduced lung function with abnormal iron status in children.

Evaluation of Respiratory Resistance as a Predictor for Oral Appliance Treatment Response in Obstructive Sleep Apnea: A Pilot Study

The aim of this study was to determine the utility of respiratory resistance as a predictor of oral appliance (OA) response in obstructive sleep apnea (OSA). Twenty-seven patients with OSA (mean respiratory event index (REI): 17.5 ± 6.5 events/h) were recruited. At baseline, the respiratory resistance (R20) was measured by impulse oscillometry (IOS) with a fitted nasal mask in the supine position, and cephalometric radiographs were obtained to analyze the pharyngeal airway space (SPAS: superior posterior airway space, MAS: middle airway space, IAS: inferior airway space). The R20 and radiographs after the OA treatment were evaluated, and the changes from the baseline were analyzed. A sleep test with OA was carried out using a portable device. The subjects were divided into Responders and Non-responders based on an REI improvement ≥ 50% from the baseline, or REI < 5 after treatment, and the R20 reduction rate between the two groups were compared. The subjects comprised 20 responders and 7 non-responders. The R20 reduction rate with OA in responders was significantly greater than it was in non-responders (14.4 ± 7.9 % versus 2.4 ± 9.8 %, p < 0.05). In responders, SPAS, MAS, and IAS were significantly widened and R20 was significantly decreased with OA (p < 0.05). There was no significant difference in non-responders (p > 0.05). A logistic multiple regression analysis showed that the R20 reduction rate was predictive for OA treatment responses (2% incremental odds ratio (OR), 24.5; 95% CI, 21.5–28.0; p = 0.018). This pilot study confirmed that respiratory resistance may have significant clinical utility in predicting OA treatment responses.

Low gestational vitamin D level and childhood asthma are related to impaired lung function in high-risk children

BACKGROUND

Lung function impairment in early life often persists into adulthood. Therefore, identifying risk factors for low childhood lung function is crucial.

OBJECTIVE

We examined the effect of 25-hydroxyvitamin D (25[OH]D) level and childhood asthma phenotype on childhood lung function in the Vitamin D Antenatal Asthma Reduction Trial (VDAART).

METHODS

The 25(OH)D level was measured at set time points in mothers during pregnancy and in children during early life. On the basis of parental reports, children were categorized into 3 clinical phenotypes: asymptomatic/infrequent wheeze, early transient wheeze, and asthma at age 6 years. Lung function was assessed with impulse oscillometry at ages 4, 5, and 6 years and with spirometry at ages 5 and 6 years.

RESULTS

A total of 570 mother-child pairs were included in this post hoc analysis. Mean gestational 25(OH)D-level quartiles were negatively associated with child respiratory resistance at 5 Hz (R5) from age 4 to 6 years (β, -0.021 kPa/L/s; 95% CI, -0.035 to -0.007; P = .003) and positively associated with FEV₁ (β, 0.018 L; 95% CI, 0.005-0.031; P = .008) and forced vital capacity (β, 0.022 L; 95% CI, 0.009-0.036; P = .002) from age 5 to 6 years. Children with asthma at age 6 years had lower lung function from age 4 to 6 years than the asymptomatic/infrequent wheeze group (β, 0.065 kPa/L/s; 95% CI, 0.028 to 0.102; P < .001 for R5 and β, -0.063 L; 95% CI, -0.099 to -0.028; P < .001 for FEV₁).

CONCLUSIONS

Low gestational 25(OH)D level and childhood asthma are important risk factors for decreased lung function in early childhood.

The roles of impulse oscillometry in detection of poorly controlled asthma in adults with normal spirometry

BACKGROUND

Impulse oscillometry (IOS) has been introduced as a method of assessing asthma control. However, the cutoff IOS values for the detection of asthma control in adults are still unclear.

OBJECTIVE

To assess the diagnostic ability of IOS for distinguishing between poorly controlled and well controlled adult asthmatic subjects with normal spirometry.

METHODS

This cross-sectional study was conducted at the Lung Health Center, Chiang Mai, Thailand, between July 2019 and June 2020. IOS and spirometry were performed in all adult asthmatic subjects but only subjects with normal spirometry were enrolled. Poorly controlled asthma was defined in accordance with the Global Initiative for Asthma (GINA) plus an asthma control test (ACT) score ≤19. A Receiver Operating Characteristic (ROC) curve was plotted to detect poorly controlled asthma using the area under the ROC (AuROC) and 95%CI.

RESULTS

One hundred and forty-two adult asthmatic subjects registering normal spirometry with a mean age of 53.4 ± 15.8 years were enrolled. Eighty-nine (62.7%) subjects were female. IOS parameters including heterogeneity of resistance at 5 Hz and resistance at 20 Hz (R5-R20) and area under reactance (AX) demonstrated excellent detection of poorly controlled asthma with an AuROC of 0.911 and 0.904, respectively. The z-score or absolute value of R5-R20 ≥ 0 and 1 cmH₂O/L/s, respectively, represented the highest AuROC of 0.86, with a sensitivity and a specificity of ≥80.0% for the detection of poorly controlled asthma.

CONCLUSION

IOS is a valuable tool for the detection of poorly controlled asthma in adults with normal spirometry.

What Is Most Suitable for Children With Cystic Fibrosis-The Relationship Between Spirometry, Oscillometry, and Multiple Breath Nitrogen Washout

INTRODUCTION

In cystic fibrosis (CF), pathological lung changes begin early in life. The technological progress currently gives many diagnostic possibilities. However, pulmonary function testing in children remains problematic.

OBJECTIVES

Our study aimed to correlate the results of impulse oscillometry (IOS) with those of multiple breath nitrogen washout (MBNW) in our pediatric CF population. We also compared those parameters between the groups with and without spirometric features of obturation.

METHODS

We collected 150 pulmonary function test sets, including spirometry, IOS, and MBNW in patients with CF aged 12.08 ± 3.85 years [6-18]. The study group was divided into two subgroups: IA (without obturation) and IB (with obturation). We also compared Sacin, Scond, and oscillometry parameters of 20 patients aged 14-18 years who reached the appropriate tidal volume (VT) during MBNW.

RESULTS

Statistical analysis showed a negative correlation between lung clearance index (LCI) and spimoetric parameters. Comparison of subgroups IA (n = 102) and IB (n = 48) indicated a statistically significant difference in LCI (p < 0.001) and FEV1z-score (p < 0.001), FEV1% pred (p < 0.001), MEF25z-score (p < 0.001), MEF50 z-score (p < 0.001), MEF75 z-score (p < 0.001), R5% pred (p < 0.05), and R20% pred (p < 0.01). LCI higher than 7.91 was found in 75.33% of the study group, in subgroup IB-91.67%, and IA-67.6%.

CONCLUSIONS

LCI derived from MBNW may be a better tool than IOS for assessing pulmonary function in patients with CF, particularly those who cannot perform spirometry.

Assessment of airway reversibility in asthmatic children using forced oscillation technique - A single-center experience from North India

Background:

Lung function testing is recommended for the management of asthma. Due to certain limitations of conventional spirometry in vulnerable patients, forced oscillation technique (FOT) has been studied with promising results. As there is a paucity of data from developing world, we planned to conduct this study in children using FOT. To assess airway reversibility after inhaled salbutamol in asymptomatic children with suspected asthma.

Settings:

This study was conducted at pediatric asthma clinic of a tertiary care referral hospital in North India.

Design:

This was a prospective interventional study over 1-year period.

Subjects and Methods:

Asymptomatic children between 2 and 18 years of age, with history suggestive of asthma, were eligible for participation. Baseline and postbronchodilator pulmonary functions were assessed using FOT. Airway resistance and reactance were monitored at various frequencies. SPSS version 17 was used for statistical analysis.

Results:

Among the 345 enrolled children, baseline mean ± standard deviation total airway resistance (R₅), central airway resistance (R₁₉), peripheral airway resistance (R₅–R₁₉), reactance (X₅), and resonant frequency (Fres) were 6.85 ± 2.60, 5.23 ± 1.93, 1.6 ± 1.16, and − 2.54 ± 1.36 cmH₂O/L/s and 17.28 ± 3.06 Hz. The median (interquartile range) percentage change after inhaled salbutamol was 19.9 (11.40, 29.12), 22.86 (6.88, 38.76), 14.08 (3.40, 22.62), 39.20 (8.20, 62.39), and 15.79 (8.33, 27.27) in respective parameters. All changes were statistically significant. The studied respiratory variables were in maximum negative correlation with height, followed by body mass index.

Conclusions:

FOT is a simple technique for monitoring lung functions in children during asthma management.

Comparison of 12-Week Additional Effect Features of Formoterol Co-Inhalation and Tulobuterol Patch on Budesonide Inhalation in Elderly Patients With Asthma

Background

For asthma strategy, to avoid the aggravation of bronchial inflammation and contraction, the long acting beta agonist (LABA) addition on inhaled corticosteroids (ICS) has been recommended.

Objectives

To know whether there is any clinical difference between the additional efficacies of Formoterol (FOR) and Tulobuterol (TUL) onto Budesonide (BUD) may be useful for the elderly patients' asthma treatment strategy.

Methods

Eighteen outpatients with mild to moderate bronchial asthma with FEV1.0% < 80% treated by intermediate ICS dosages visited Respiratory Division of Nagasaki University Hospital or Isahaya General Hospital, Japan Community Health care Organization were subjected, and were randomly assigned (9 cases per group) to either the FBC group (BUD/FOR 160/4.5 µg, 2 inhalations twice daily) or BUD + TUL group (BUD 200 mcg: 2 inhalations twice daily + TUL 2 mg daily) and were compared in parallel with 2 arms for 12 weeks prospectively. Peak expiratory flow, forced expiratory volume in 1 second, impulse oscillometry (IOS), fractional exhaled nitric oxide (FeNO), Asthma Control Questionnaire, mini-Asthma Quality of Life Questionnaire (mini-AQLQ), and occurrence of adverse reactions were compared.

Results

The "Fres" of IOS was improved in FBC group (p = 0.03). The "emotion" domain of mini-AQLQ was improved in BUD + TUL group (p = 0.03).

Conclusion

By changing the drug formulation, the patch was superior in terms of satisfaction, but it was thought that the inhaled combination was superior in improving the respiratory function itself. It is necessary to pay attention to the characteristics of the patient when selecting treatment.

Assessment of pulmonary function by impulse oscillometry and spirometry in children with type 1 diabetes mellitus

AIM

To assess the lung functions with impulse oscillometry (IOS) and spirometry in children with type 1 diabetes mellitus (T1DM).

METHODS

Fifty-one children with T1DM, and sex- and age-matched 53 healthy control (HC) subjects were included in this study. Demographic, clinical, and laboratory characteristics of the subjects were recorded and their pulmonary functions were analyzed by IOS and spirometry.

RESULTS

In IOS, zR5, zR10, and zR20 levels were higher in children with T1DM compared with HCs (P = .019, P = .017, and P = .002, respectively). In spirometry, zFEF75 and zFEF25-75 were lower in children with T1DM compared with HCs (P = .025, P = .001, respectively). In IOS, zR5-20 (P = .008, P = .005, respectively) and zAX (P = .013, P = .009, respectively) were significantly lower in good-controlled group compared with moderate- and poor-controlled group. In spirometry, zFEF25-75 was significantly higher in good-controlled group compared with moderate- and poor-controlled group (P = .005, P = .009, respectively). HbA1c was positively correlated with zR5-20 value (r = .339; P = .017) in male children with T1DM. The duration of the disease was positively correlated with zR5-20 (r = .290; P = .043) and zFres (r = .358; P = .010). According to the receiver operating characteristic curve analysis to estimate optimal cut-offs to discriminate good control level of T1DM (HbA1c < 7%), a zR5-20 ≤ 2.28 demonstrated a 75.0% sensitivity and 82.9% specificity, with an area under the curve of 0.805 ([confidence interval, 0.615-0.995]; P = .007).

CONCLUSIONS

This study showed subclinical impairment of lung functions which is associated with disease duration and the degree of metabolic control in children with T1DM.

Diagnostic Ability of Impulse Oscillometry in Diagnosis of Chronic Obstructive Pulmonary Disease

The diagnosis of chronic obstructive pulmonary disease (COPD) mainly relies on spirometry. Due to the complexity of spirometry, easier-to-do impulse oscillometry (IOS) has been introduced as a complementary approach to conventional pulmonary function testing. Therefore, this study aimed to assess the efficacy of the diagnostic ability of IOS for diagnosing chronic obstructive pulmonary disease (COPD). This cross-sectional study was conducted at the Lung Health Center, Chiang Mai University, Thailand, between June 2019 and January 2020. IOS and spirometry were performed with all subjects suspected of having COPD. A Receiver Operating Characteristic (ROC) curve was plotted, the area under the ROC (AuROC) and 95%CI were compared among COPD and chronic smokers. One hundred and seventeen subjects suspected of having COPD with a mean age of 68.6 ± 8.6 years old were enrolled. Of these 103 (88.0%) were male. Thirty healthy subjects were also enrolled. IOS parameters including resistance at 5 Hz (R5), resonant frequency (Fres), area under reactance (AX), heterogeneity of resistance (R5-R20), and reactance at 5 Hz (X5) demonstrated excellent overall accuracy relative to the diagnosis of COPD with an AuROC ranging from 0.80 - 0.84. The AX ≥ 8.66 cmH₂O/L represented an AuROC = 0.79, with a sensitivity of 79.1% and a specificity of 78.0% for the diagnosis of COPD. IOS is a valuable tool for use in the diagnosis of COPD. It may be used in subjects who cannot carry out the spirometric procedure.

Methacholine-Induced Cough in the Absence of Asthma: Insights From Impulse Oscillometry

Introduction

The pathophysiologic differences between methacholine-induced cough but normal airway sensitivity (COUGH) and healthy individuals (CONTROL) are incompletely understood and may be due to differences in the bronchodilating effect of deep inspirations (DIs). The purpose of this study is to compare the bronchodilating effect of DIs in individuals with classic asthma (CA), cough variant asthma (CVA), and COUGH with CONTROL and to assess impulse oscillometry (IOS) measures as predictors of the bronchodilating effect of DIs.

Methods

A total of 43 adults [18 female; 44.8 ± 12.3 years (mean ± SD); n = 11 CA, n = 10 CVA, n = 7 COUGH, n = 15 CONTROL] underwent modified high-dose methacholine challenge, with IOS and partial/maximal expiratory flow volume (PEFV/MEFV) maneuvers (used to calculate DI Index) to a maximum change (Δ) in FEV₁ of 50% from baseline (MAX). Cough count and dyspnea were measured at each dose. The relation between IOS parameters and DI Index was assessed at baseline and MAX using multivariable linear regression analysis.

Results

Cough frequency, dyspnea intensity, and baseline peripheral resistance (R5-R20) were significantly greater in COUGH compared with CONTROL (p = 0.006, p = 0.029, and p = 0.035, respectively). At MAX, the DI Index was significantly lower in COUGH (0.01 ± 0.36) compared with CA (0.67 ± 0.97, p = 0.008), CVA (0.51 ± 0.73, p = 0.012), and CONTROL (0.68 ± 0.45, p = 0.005). Fres and R5-R20 were independent IOS predictors of the DI Index.

Conclusion

The bronchodilating effect is impaired in COUGH and preserved in mild CA, CVA, and CONTROL. Increased peripheral airway resistance and decreased resonant frequency are associated with a decreased DI Index. COUGH is a clinical phenotype distinct from healthy normals and asthma.

Agreement between spirometry and impulse oscillometry for lung function assessment in 6-year-old children born extremely preterm and at term

BACKGROUND

Extremely preterm birth is a risk factor for reduced lung function later in life, and clinical follow-up from early childhood is recommended. Dynamic spirometry is the most widely used method to assess airway obstruction, but impulse oscillometry (IOS) may be an alternative method that is easier to perform in young children. The feasibility and agreement between spirometry and IOS outcome variables has not been investigated in children born extremely preterm.

AIM

To determine the feasibility of and correlation between spirometry and IOS in pre-school children born extremely preterm.

METHODS

Spirometry and IOS were performed in 6-year-old children born extremely preterm (n = 88) and age-matched term controls (n = 84) in Stockholm, Sweden. Correlations between spirometry and IOS outcome variables were analyzed using Pearson's partial correlation, adjusting for height.

RESULTS

Success rate for spirometry (60%) was lower than for IOS (93%) but did not differ significantly between the preterm and term groups (56% and 64% for spirometry, P = .25; and 92% and 94% for IOS, P = .61). Correlations between spirometry and IOS outcomes were at best moderate (Spearman's r = -0.31 to -0.56). Normal IOS identified 69% to 90% of those with normal spirometry. A negative predictive value of 90% was found for R5-R20 versus FEV_0.75 /FVC, suggesting that IOS may be used to exclude obstructive airway disease as measured by spirometry.

CONCLUSION

IOS is a more feasible method than spirometry to assess lung function in young children irrespective of gestational age at birth and could be considered an alternative in children who cannot perform spirometry.

Correlations of forced oscillometric bronchodilator response with airway inflammation and disease duration in asthma

INTRODUCTION

Airway resistance and reactance, measured by forced oscillometry, are used to measure the airway obstruction in patients with asthma.

OBJECTIVES

This study aimed to investigate the oscillometric bronchodilator responses in treated and untreated asthma and evaluate its association with airway inflammation and disease duration.

MATERIALS AND METHODS

This study included 30 nonsmoking patients with mild to moderate treated asthma, 25 patients with newly diagnosed untreated asthma and 29 control subjects. Spirometric and oscillometric measurements were performed before and after inhalation of 400 µg salbutamol. Disease duration was defined as the number of years since asthma diagnosis.

RESULTS

At airway resistance of 5 Hz (R5) and 20 Hz (R20), bronchodilator responses in patients with untreated and treated asthma were greater than those in control subjects. In patients with untreated asthma, higher fractional exhaled nitric oxide concentration (FeNO) levels were strongly correlated with greater reversibility of R20 (r_s  = -0.621, P < 0.001). In patients with treated asthma, there was no significant association between FeNO and oscillometric reversibility, whereas longer disease duration was significantly associated with lesser bronchodilator response at R20 (r_s  = 0.441, P < 0.05). Treated asthma patients with longer disease duration (≥10 years) showed significantly higher post-bronchodilator R5 and R20 than the treated asthma patients with shorter disease duration (<10 years).

CONCLUSION

The present study provides further evidence of an association between airway inflammation and variable airway obstruction in asthma patients and indicates that long-term disease duration could be related to poorly reversible airway resistance in patients with mild to moderate asthma.