Small airway dysfunction (SAD) is a clinically important problem in asthmatics. Impedance (Z) measurement by oscillometry is considered a reliable, easy to perform and quick technique to determine SAD. Limited data are available about the presence of SAD in subjects with past history of asthma/asthmatic bronchitis. The aim of the current study is to assess SAD with Z in past (PA) and current asthmatics (CA).
Methods
We included 7219 subjects aged 18-82 years from the Austrian LEAD study, a longitidinal population-based cohort study. Based on questionnaire data, we identified:(1) healthy participants without respiratory pathologies and symptoms (N=6559), (2) subjects reporting past diagnosis of asthma (N=315) and (3) subjects with current asthma (N=345). Resistance (R5) and Reactance (X5) at 5 Hz, the area under X (AX), and the frequency dependence of R (R5-R19) were analyzed.
Results
|
Parameter |
Healthy (N:6559) |
Past Asthma ( N: 315) |
Current asthma (N: 345) |
| dX5 | -0.14 ( -0.33; 0.10) | -0.10 (-0.31; 0.18) | -0.05 ( -0.28; 0.24)* |
| R5 %pred | 83 (69;101) | 88 (75;108)* | 93 (79; 113)* |
| X5 %pred | 82 (60;109) | 82(63;115) | 94 (68;132 )*° |
| AX %pred | 134 (79; 227) | 134(81;239) | 190(97;367)*° |
| R5-R19 %pred | 69 (-79;223) | 64 (-54; 222) | 104 (-70;346)* |
* p<0.05 with healthy. ° p<0.05 with Past asthma. % predicted according to Berger et al. (2021). Data are presented as median (IQR).
Subjects with current asthma when compared to healthy subjects presented oscillometry parameters compatible with SAD. Subjects with past asthma presented with higher R5.
Conclusion
Our population-based data confirm the presence of Z changes, indicative of SAD in current asthmatics. Oscillometry may identify SAD in asthmatics and sharpen therapy management.