Relating small airways to asthma control by using impulse oscillometry in children

Abstract

Background Previous reports suggest that peripheral airways are associated with asthma control. Patient history, although subjective is used largely to assess asthma control in children because spirometry is many times normal. Impulse oscillometry (IOS) is an objective non-invasive measurement of lung function, which has the potential to examine independently both small and large airway obstruction. Objective To determine the utility of IOS in assessing asthma control in children. Methods Asthmatic and healthy children (6–17 yrs) were enrolled in the study. Spirometry and IOS (resistance at 5 and 20 Hz, R5 and R20, respectively, reactance at 5 Hz, X5, resonant frequency, Fres, and area under the reactance curve between 5 Hz and Fres, AX) were collected in triplicate before and after a bronchodilator was administered. The physicians were blinded to the IOS measurements and assessed asthma control using ATS guidelines. Results Small airway IOS measurements, including R5-20, X5, Fres and AX, of children with uncontrolled asthma (n=44) were significantly different from those of controlled asthmatic (n=57) and healthy (n=14) children, especially prior to the administration of a bronchodilator. However, there was no difference in large airway IOS (R20). No differences were found between controlled asthmatic and healthy children in any of the endpoints. ROC analysis showed cut-points for baseline R5-20 (1.5 cmH2O·L−1·s) and AX (9.5 cmH2O·L−1) that effectively discriminated controlled versus uncontrolled asthma (AUC=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 may be a reliable non-invasive method to assess asthma control in children.

Lung Function at 8 and 16 Years After Moderate-to-Late Preterm Birth: A Prospective Cohort Study

“…The IOS results at age 16 years revealed significantly higher estimated medians for R 5 , R [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] , and AX 0.5 in moderate to late preterm male subjects compared with term male subjects ( Table 2). Although a similar trend was seen for female subjects, a significant difference was recorded only for R 5 .…”

“…Quality control was performed at the time of examination by visual inspection of the waveforms. Given that coherence, which is a measure of testing reliability, was >0.80 at 10 Hz, the mean value of resistance at 5 Hz (R 5 ), resistance at 20 Hz (R 20 ), frequency dependence of resistance (ie, R [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], and reactance area (AX) were used for analysis. AX may boost the assessed response inappropriately compared with the R 5-20 response because it multiplies 2 partly independent reactions of the airways.…”

“…12,13 Furthermore, although spirometry is a well-established method to assess lung function by measuring expiratory flow rates and volumes, other lung function techniques aiming to assess peripheral airway function and mechanics, such as forced oscillation, have been shown to be more sensitive than spirometry for detection of airway obstruction in children with lung disease, including follow-up studies of children born very preterm. [14][15][16][17][18] We hypothesized that being born moderate to late preterm would have a negative effect on lung function through childhood and adolescence. Therefore, the aim of the present study was to determine associations between moderate to late preterm birth and various aspects of later lung function (measured by using spirometry at ages 8 and 16 years, and by using impulse oscillometry [IOS] at 16 years) with data from a large, prospective birth cohort.…”

The Biomarker Salivary SP-D May Indicate Small Airway Inflammation and Asthma Exacerbation

“…Shi et al [25] demonstrated that increased peripheral airway indexes of FOT, including R5-R20 and ALX, predict asthma exacerbation. We thus asked whether salivary SP-D levels were associated with the severity of an acute asthma attack, as assessed by AAIRS [22].…”

Application of impulse oscillometry and bronchial dilation test for analysis in patients with asthma and chronic obstructive pulmonary disease

“…It measures both small and large airways resistance and resonance capacitance of the lung [11]. Due to detecting large and small airways diseases separately, IOS has been applied in asthma diagnosis and management [12][13][14].…”