Measuring bronchodilation in COPD clinical trials

Abstract

AimsThe aim of this study was to compare the variability and sensitivity of impulse oscillometry (R5, X5 and RF), plethysmography (Raw and sGaw) and spirometry (FEV 1 , FVC and MMEF) in order to determine the most powerful technique for assessing bronchodilation in COPD clinical trials. MethodsTwenty-four patients with COPD had impulse oscillometry, plethysmography and spirometry measured twice 30 mins apart, to determine variability. Then ascending doses of salbutamol (20, 50, 100, 200, 400 and 800 m g) were given and the same measurements made after each dose. Significant changes greater than variability were determined for each performed measurement (expressed as mean percentage improvement with 95% CI). ResultsSignificant effects ( P < 0.05) were detected after 20 m g by X5 (18.5% CI 9.8-27.2) RF (11.1% CI 7.2-15.0) and sGaw (21.5% CI 10.1-32.9), and after 50 m g by R5 (16.7% CI 10.8-22.5) and . FEV 1 was less sensitive, detecting significant bronchodilation at 100 m g (10.2% CI 7.4-12.9). ConclusionsWe conclude that impulse oscillometry and plethysmography should be considered the preferred techniques for measuring bronchodilation in COPD clinical trials.

Superiority of "triple" therapy with salmeterol/fluticasone propionate and tiotropium bromide versus individual components in moderate to severe COPD

“…We used the sensitive pulmonary function measurement of specific airway conductance as the primary end point to compare the different treatment regimens. [18][19][20][21] Pulmonary function measurements of spirometry and lung volumes were also performed, and symptom scores were evaluated.…”

Bronchodilating effect of combined therapy with ipratropium bromide and ondansetron in patients with COPD

“…Unlike spirometry, these tests do not require effort dependent forced expiration. In patients with COPD experiencing bronchodilation induced by increasing doses of salbutamol, the shape of the dose-response curves was different for sGaw compared to other measurements; there was an initial sharp improvement in sGaw at low doses of salbutamol, after which the gradient of the curve was similar to other readings (34). This intial rapid improvement in airway conductance may explain the increased sensitivity of plethysmography compared with the other methods at low bronchodilator doses.…”

“…In a recent publication, spirometry, plethysmography and impulse oscillometry were compared in their ability to measure bronchodilation induced by inhalation of increasing doses of salbutamol in patients with COPD. For the lower doses of salbutamol, plethysmography (sGaw) and impulse oscillometry were more sensitive than FEV1 in detecting bronchodilation; on the other hand, sGaw was the most variable measurement, followed by oscillometry parameters, with spirometry (FEV1) being the least variable (34). Plethysmography measures airway resistance, conductance and lung volumes while impulse oscillometry measures airway resistance and lung reactance (35).…”

Update on the roles of distal airways in COPD

“…Finally, it was recently shown that ''distal'' oscillometry parameters (R5Hz-R20Hz and X5Hz), measured at baseline breathing and at an elevated respiratory rate (40 breaths?min -1 ), correlated perfectly with the fall of dynamic compliance at 60 breaths?min -1 , a reference invasive technique used to assess the distal airways [124]. Impulse oscillometry is also useful for evaluating responses to short-and long-acting bronchodilators and here it is suggested to be more sensitive than spirometry in comparing drugs [125,126]. The clinical relevance of oscillometry parameters in COPD was recently analysed by HARUNA et al [127].…”