Background: COPD is a common chronic respiratory disease induced by smoking or exposition to noxious gases. The most disabling symptom is dyspnea and the first-line treatment to improve symptoms are bronchodilators. Usually, bronchodilator response is determined by the improvement of forced expiratory volume in one second (FEV₁) which is not well correlated to dyspnea. As the forced oscillation technique (FOT) allow to measure parameters related to lung hyperinflation, hallmark of severe COPD, which are better correlated with dyspnea, we reasoned that FOT might be an interesting tool to assess the bronchodilator response in COPD.
- assess bronchodilator response both with conventional respiratory function tests and FOT, with a particular interest for reactance parameters which have been linked to lung hyperinflation. - assess the correlation between respiratory parameters and intensity of dyspnea - determine if changes in reactance parameters after bronchodilator administration are more closely related to those of IC than those of FEV₁. - determine which changes in respiratory function parameters could predict a clinically significant improvement in IC.
Methods: 26 COPD patients were recruited. They were tested for conventional tests as well as with FOT both before and after bronchodilator administration (80 µg of ipratropium bromide and 200 µg of fenoterol hydrobromide).
Analysis: A majority of the parameters responded significantly after bronchodilator administration. A reactance parameter came out to be very interesting; the area above the reactance-frequency curve at 5Hz (AX5) which improved highly significantly after bronchodilator administration (p-value<0,001). More importantly, AX5 was correlated with dyspnea (r = 0,41, p-value<0,05) and the changes in AX5 were better correlated with the changes in IC (r = -0,58, p-value<0,01) than the changes in FEV₁ (r = 0,47, p-value<0,05). Finally, AX5 was shown to be a good predictor for a clinical and significant change in IC, as determined by ROC analysis (AUC=0,80, p-value<0,01).
Conclusion: AX5 parameter appears to be an interesting index for the assessment of the bronchodilator response. FOT also gives additional information to that of conventional respiratory function tests. Accordingly, and because of its ease of use, FOT appears to be an interesting method to assess bronchodilator response.
|la date de réponse||23 janv. 2020|
|Superviseur||ERIC MARCHAND (Promoteur)|