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Conducting Respiratory Oscillometry in an Outpatient Setting
Published on: April 8, 2022
Relating small airways to asthma control by using impulse oscillometry in children
Yixin Shi1, Anna S Aledia, Ahramahzd V Tatavoosian
1Department of Biomedical Engineering, University of California, Irvine, CA 92697-2730, USA.
Insights
Impulse oscillometry (IOS) effectively identifies small-airway dysfunction in children with uncontrolled asthma, offering a reliable, noninvasive method for assessing asthma control. This objective lung function measurement shows significant differences compared to subjective patient history.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Asthma Research
Background:
- Peripheral airway involvement is linked to asthma control.
- Subjective patient history is often used for pediatric asthma assessment due to normal spirometry.
- Impulse oscillometry (IOS) offers objective, noninvasive lung function assessment for small and large airways.
Purpose of the Study:
- To evaluate the utility of impulse oscillometry (IOS) in assessing asthma control in pediatric patients.
- To determine if IOS can differentiate between controlled, uncontrolled, and healthy children.
Main Methods:
- Asthmatic and healthy children (6-17 years) underwent spirometry and IOS measurements (R5, R20, X5, Fres, AX) before and after bronchodilator administration.
- Physicians assessed asthma control using American Thoracic Society guidelines, blinded to IOS results.
- IOS parameters included resistance (R5, R20), reactance (X5), resonant frequency (Fres), and reactance area (AX).
Main Results:
- Small-airway IOS measures (R5-20, X5, Fres, AX) significantly differed in children with uncontrolled asthma versus controlled or healthy children, particularly pre-bronchodilator.
- No significant differences in large-airway IOS (R20) or between controlled asthma and healthy children were observed.
- Receiver operating characteristic analysis identified cut points for R5-20 and AX that accurately discriminated controlled from uncontrolled asthma with >80% classification accuracy.
Conclusions:
- Uncontrolled asthma is associated with small-airway dysfunction.
- IOS demonstrates potential as a reliable and noninvasive tool for assessing pediatric asthma control.
- Objective IOS measurements may supplement or replace subjective assessments in pediatric asthma management.
Background:
Previous reports suggest that the peripheral airways are associated with asthma control. Patient history, although subjective, is used largely to assess asthma control in children because spirometric results are many times normal values. Impulse oscillometry (IOS) is an objective and noninvasive measurement of lung function that has the potential to examine independently both small- and large-airway obstruction.
Objective:
We sought to determine the utility of IOS in assessing asthma control in children.
Methods:
Asthmatic and healthy children (6-17 years) were enrolled in the study. Spirometric and IOS (resistance of the respiratory system at 5 Hz [R5] and 20 Hz [R20], reactance of the respiratory system at 5 Hz [X5], resonant frequency of reactance [Fres], and area under the reactance curve between 5 Hz and Fres [reactance area {AX}]) values were collected in triplicate before and after a bronchodilator was administered. The physicians were blinded to the IOS measurements and assessed asthma control using American Thoracic Society guidelines.
Results:
Small-airway IOS measurements, including the difference of R5 and R20 [R5-20], X5, Fres, and AX, of children with uncontrolled asthma (n = 44) were significantly different from those of children with controlled asthma (n = 57) and healthy children (n = 14), especially before the administration of a bronchodilator. However, there was no difference in large-airway IOS values (R20). No differences were found between children with controlled asthma and healthy children in any of the end points. Receiver operating characteristic analysis showed cut points for baseline R5-20 (1.5 cm H(2)O · L(-1) · s) and AX (9.5 cm H(2)O · L(-1)) that effectively discriminated controlled versus uncontrolled asthma (area under the curve, 0.86 and 0.84) and correctly classified more than 80% of the population.
Conclusion:
Uncontrolled asthma is associated with small-airways dysfunction, and IOS might be a reliable and noninvasive method to assess asthma control in children.
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