Application of Impulse Oscillometry in Adult Asthmatic Patients With Preserved Lung Function

Abstract

Purpose It is difficult to assess airway obstruction using spirometry in adult asthmatic patients with preserved lung function. Impulse oscillometry (IOS) can detect not only airway resistance but also reactance. Therefore, IOS may be useful in assessing pulmonary function in such patients. We investigated the applicability of IOS for asthma patients with preserved lung function. Methods Between 2015 and 2018, 1,248 adult asthmatic patients suspected of having asthma who visited the Allergy and Asthma Center of Severance Hospital underwent both spirometry and IOS. Consequently, 784 patients had asthma, 111 had chronic obstructive lung disease (COPD) or asthma-COPD overlap, and 7 had parenchymal lung disease. The remaining 346 patients had chronic cough without underlying lung or airway disease. Among the 784 asthmatic patients, 191 with decreased lung function (predicted forced expiratory volume in 1 second [FEV1] < 80%) were excluded. Propensity score matching was performed to adjust baseline characteristics between 346 non-asthmatic and 593 asthmatic patients with preserved lung function. Subsequently, we compared the spirometry and IOS parameters between the 329 asthmatic and 329 non-asthmatic patients. Results Multiple logistic regression analysis showed that the area of reactance (AX) was associated with asthma with preserved lung function. In receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) of AX (AUC = 0.6823) for asthma was not significantly different from that of FEV1 (AUC = 0.6758). However, the AUC of a combination of AX and FEV1 (AUC = 0.7437) for asthma was significantly higher than that of FEV1 alone. The cutoff value of AX was 0.51 kPa/L in univariate ROC analysis. Conclusions AX is associated with adult asthma with preserved lung function. Performing spirometry together with IOS is more beneficial than performing spirometry alone for diagnosing asthma in adult patients with preserved lung function.

Reference values of impulse oscillometry (IOS) for healthy Chinese children aged 4–17 years

“…First, similar to other IOS reference studies, this cross-sectional study had limited interpretation of longitudinal changes in lung function. In addition, IOS measurements did not include the area of reactance (AX), which is considered a useful parameter in the evaluation of children with asthma [ 34 , 35 ]. Finally, the healthy children in this study were defined through the questionnaire survey and did not undergo blood IgE screening and chest X-ray, which could not completely exclude children with allergic diseases and lung disease.…”

Clinical significance and applications of oscillometry

“…Oscillometric measurements can distinguish adult asthmatics from healthy controls [14][15][16], asthmatics with different degrees of airway obstruction [17], and between groups of adults with asthma compared to COPD [15,[18][19][20][21]. Oscillometry may be especially helpful in diagnosing asthma in patients with preserved spirometry as a more sensitive indicator of abnormal airway physiology [22]. However, while…”

Reference values of impulse oscillometry (IOS) for healthy Chinese children aged 4-17 years

“…First, like other PFT references study, this cross-sectional study had limited interpretation of longitudinal changes in lung function. In addition, IOS measurements did not include area of reactance (AX), which is considered as a useful parameter in the evaluation of children with asthma [27,28] . Finally, the healthy children in this study only passed the questionnaire survey and did not carry out blood IgE screening and chest X-ray, which could not completely exclude the children with allergic diseases and lung disease.…”