<p>Correlation between impulse oscillometry parameters and asthma control in an adult population</p>

Abstract

Purpose: Impulse oscillometry (IOS) has been proposed as an alternative test to evaluate the obstruction of small airways and to detect changes in airways earlier than spirometry. In this study, we sought to determine the utility and association of IOS parameters with spirometry and asthma control in an adult population. Patients and methods: Adults 14–82 years of age with asthma were classified into uncontrolled asthma (n=48), partially controlled asthma (n=45), and controlled asthma (n=49) groups, and characterized with fractional exhaled nitric oxide (FE NO ), IOS, and spirometry in a transversal analysis planned as a one-visit study. The basic parameters evaluated in IOS are resistance at 5 Hz (R 5 ), an index affected by the large and small airway; resistance at 20 Hz (R 20 ), an index of the resistance of large airways; difference between R 5 and R 20 (R 5 –R 20 ), indicative of the function of the small peripheral airways; reactance at 5 Hz (X 5 ), indicative of the capacitive reactance in the small peripheral airways; resonance frequency (Fres), the intermediate frequency at which the reactance is null, and reactance area (XA), which represents the total reactance (area under the curve) at all frequencies between 5 Hz to Fres. Results: There were statistical differences between groups in standard spirometry and IOS parameters reflecting small peripheral airways (R 5 , R 10 , R 5 –R 20 , Fres, XA and X 5 ) ( P <0.001). Accuracy of IOS and/or spirometry to discriminate between controlled asthma vs partially controlled asthma and uncontrolled asthma was low (AUC=0.61). Using linear regression models, we found a good association between spirometry and IOS. In order to evaluate IOS as an alternative or supplementary method for spirometry, we designed a predictive model for spirometry from IOS applying a penalized regression model (Lasso). Then, we compared the original spirometry values with the values obtained from the predictive model using Bland–Altman plots, and the models showed an acceptable bias in the case of FEV 1 /FVC, FEV 1 %, and FVC%. Conclusion: IOS did not show a discriminative capacity to correctly classify patients according to the degree of asthma control. However, values of IOS showed good association with values of spirometry. IOS could be considered as an alternative and accurate complement to spirometry in adults. In a predictive model, spirometry values estimated from IOS tended to overestimate in low values of “real” spirometry and underestimate in high values.

<p>Lung Function Assessment by Impulse Oscillometry in Adults</p>

“…They found associations between oscillometric values and spirometry. 27 Similar data was published by Galat et al 44 in a review article on asthma control. Carr et al 45 reviewed literature on the correlation between small airways disease and asthma control, concluding that diagnose of SAD (small airway disease) can occur with various non-invasive tests, including oscillometry, and may improve treatment response.…”

“…Studies showed that FOT has more sensitivity than spirometry in the case of children as a predictor of asthma and response to treatment. 16 , 27 When evaluating BD response, King et al 8 recommend the definition of a positive response as a decrease in Rrs5 with −40%, an increase in Xrs5 with +50% and decrease in AX with −80%. da Costa et al 28 studied the impedance changes after administration of salbutamol in the case of healthy and COPD patients, showing that oscillometric parameters are highly sensitive to broncho-dilatation, especially in early stages of COPD.…”

Impulse Oscillometric Evaluation of Airway Resistance in Overweight and Obese Children With Asthma

“…We found that the differences shown by spirometry in older age groups were not present in resistance and reactance values measured by IOS. IOS measures airway impedance, which is a function of resistance and reactance, thus predicts about the peripheral airway obstruction and detects inspiratory and expiratory changes in airway resistance in asthmatic children 7,18,19 .…”

“…Airway resistance at different sound frequencies measure different parts of the airway. Measurements at low frequencies reflects both the central and peripheral airways while measurement at higher frequencies reflect the larger airways thus allowing prediction of the resistance and reactance of the small airways which are known to be primary area of involvement in asthma 6,7 .…”

Airwave oscillometry and patient-reported outcomes in persistent asthma

“…However, another study concluded that IOS has no discriminative capacity to classify patients according to the degree of asthma control. 9 In the present study, we used a lower cut off for AX of 1.0 kPa/L using AOS as compared to 1.5 kPa/L using IOS in a previous study. 5 The reason for this is that AOS is more sensitive than IOS in detecting altered lung compliance.…”