Airwaves Oscillometry & Asthma

 Reviews & Editorial- 2021

Technical standards for respiratory oscillometry and bronchodilator response cut-offs. Letter to Editor. Thamrin  C, Robinson PD, Farah CS, King GG. Eur Respir J. 2022 Jan 20; 2102663. Online ahead of print.

 

Bronchodilator response in FOT parameters in middle-aged adults from SCAPIS: normal values and relationship to asthma and wheezing. Letter to Editor. Johansson H, et al. Eur Respir J. 2021 Sep 9; 58(3):2100229.

 

Repeatability of impulse oscillometry in patients with severe asthma. Letter to Editor. Chan R, Misirovs R, Lipworth B. Eur Respir J  2021 Dec 31; 59(1):2101679.

Report on medium term repeatability for IOS and spirometry and propose values for within-subject coefficient of variation (CV) & Biological variability (BV) in patients with poorly controlled severe asthma (42 patients; 27 females & 15 males; age 53 years). The mean±SD time in measurements between T1 and T2 measurements was 321±208 days (range 63–1085 days).

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The predictive value of impulse oscillometry for asthma exacerbations in childhood: A systematic review and meta-analyses. Yaoyao Ling, etal. Pediatr Pulmonol. 2021 Jul; 56(7):1850-1856.

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 {children; age of 3.6–11.2 yrs} 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.

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Small airway dysfunction and poor asthma control: a dangerous liaison. Review. Cottini M, etal. Clin Mol Allergy. 2021 May 29;19(1):7.

main goal of the current asthma treatment guidelines is to achieve clinical control, encompassing both the patient symptoms and limitations and the future risk of adverse asthma outcomes. Despite randomized controlled trials showing that asthma control is an achievable target, a substantial proportion of asthmatics remain poorly controlled in real life. The involvement of peripheral small airways has recently gained greater recognition in asthma, and many studies suggest that the persistent inflammation at these sites leads to small airway dysfunction (SAD), strongly contributing to a worse asthma control. Overall, the impulse oscillometry (IOS), introduced in the recent years, seems to be able to sensitively assess small airways, while conventional spirometry does not. Therefore, IOS may be of great help in characterizing SAD and guiding therapy choice. The aim of this article is to review the literature on SAD and its influence on asthma control, emphasizing the most recent evidence.

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Longitudinal monitoring of asthma in the clinic using respiratory oscillometry. Cottee AM, et al. Respirology. 2021;26:566-73. 

Background and objective:  Asthma guidelines emphasize the importance of assessing lung function and symptoms. The forced oscillation technique (FOT) and its longitudinal relationship with spirometry and symptoms are unresolved. We examined concordance between longitudinal spirometry, FOT and symptom control, and determined FOT limits of agreement in stable asthma.

Methods:  Over a 3-year period, adults with asthma attending a tertiary clinic completed the asthma control test (ACT), fraction of exhaled nitric oxide (FeNO), FOT and spirometry. Analysis included between-visit concordance for significant change using Cohen's kappa (κ) and stable asthma FOT limits of agreement.

Results:  Data (n = 186) from 855 visits (mean ± SD 4.6 ± 3.0 visits), 114 ± 95 days apart, were analysed. Between-visit concordance was moderate between reactance at 5 Hz (X5) and forced expiratory volume in 1 s (FEV1 ) (κ = 0.34, p = 0.001), and weak between ACT and FEV1 (κ = 0.18, p = 0.001). Change in FeNO did not correlate with lung function or ACT (κ < 0.05, p > 0.1). Stable asthma between visits (n = 75; 132 visits) had reduced lung function variability, but comparable concordance to the entire cohort. Limits of agreement for FEV1 (0.42 L), resistance at 5 Hz (2.06 cm H2 O s L-1 ) and X5 (2.75 cm H2 O s L-1 ) in stable asthma were at least twofold greater than published values in health.

Conclusion:  In adults with asthma, there is moderate concordance between longitudinal change in FOT and spirometry. Both tests relate poorly to changes in asthma control, highlighting the need for multi-modal assessment in asthma rather than symptoms alone. The derivation of longitudinal FOT limits of agreement will assist in its clinical interpretation.

Moving closer to clinical application of the forced oscillation technique in asthma monitoring?

     Editorial. Siddiqui S. Respirology. 2021 Jun;26(6):522-23.

 

Lung function testing and inflammation markers for wheezing preschool children: A systematic review for the EAACI Clinical Practice Recommendations on Diagnostics of Preschool Wheeze. Review. Elenius V, etal; EAACI Preschool Wheeze Task Force for Diagnostics of Preschool Wheeze. Pediatr Allergy Immunol. 2021 Apr;32(3):501-513.

Background:  Preschool wheeze is highly prevalent; 30%-50% of children have wheezed at least once before age six. Wheezing is not a disorder; it is a symptom of obstruction in the airways, and it is essential to identify the correct diagnosis behind this symptom. An increasing number of studies provide evidence for novel diagnostic tools for monitoring and predicting asthma in the pediatric population. Several techniques are available to measure airway obstruction and airway inflammation, including spirometry, impulse oscillometry, whole-body plethysmography, bronchial hyperresponsiveness test, multiple breath washout test, measurements of exhaled NO, and analyses of various other biomarkers.

Methods:  We systematically reviewed all the existing techniques available for measuring lung function and airway inflammation in preschool children to assess their potential and clinical value in the routine diagnostics and monitoring of airway obstruction.

Results:  If applicable, measuring FEV1 using spirometry is considered useful. For those unable to perform spirometry, whole-body plethysmography and IOS may be useful. Bronchial reversibility to beta2-agonist and hyperresponsiveness test with running exercise challenge may improve the sensitivity of these tests.

Conclusions:  The difficulty of measuring lung function and the lack of large randomized controlled trials makes it difficult to establish guidelines for monitoring asthma in preschool children.

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