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- Koopman, M., et al.
(author)
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Differential Outcomes Following 4 Weeks of Aclidinium/Formoterol in Patients with COPD: A Reanalysis of the ACTIVATE Study
- 2022
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In: International Journal of Chronic Obstructive Pulmonary Disease. - 1178-2005. ; 17, s. 517-533
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Journal article (peer-reviewed)abstract
- Rationale: It is difficult to predict the effects of long-acting bronchodilators (LABD) on lung function, exercise capacity and physical activity in patients with chronic obstructive pulmonary disease (COPD). Therefore, the multidimensional response to LABD was profiled in COPD patients participating in the ACTIVATE study and randomized to LABD. Methods: In the ACTIVATE study, patients were randomized to aclidinium bromide/formoterol fumarate ( AB/FF) or placebo for four weeks. The primary outcomes included (1) lung function as measured by functional residual capacity (FRC), residual volume (RV), and spirometric outcomes; (2) exercise performance as measured by a constant work rate cycle ergometry test (CWRT); and (3) physical activity (PA) using an activity monitor. Self-organizing maps (SOMs) were used to create an ordered representation of the patients who were randomly assigned to four weeks of AB/FF and cluster them into different outcome groups. Results: A total of 250 patients were randomized to AB/FF (n = 126) or placebo (n = 124). Patients in the AB/FF group (39.6% women) had moderate-to-severe COPD, static hyperinflation (FRC: 151.4 (27.7)% predicted) and preserved exercise capacity. Six clusters with differential outcomes were identified. Patients in clusters 1 and 2 had significant improvements in lung function compared to the remaining AB/FF-treated patients. Patients in clusters 1 and 3 had significant improvements in CWRT time, and patients in clusters 2, 3 and 6 had significant improvements in PA compared to the remaining AB/FF-treated patients. Conclusion: Individual responses to 4 weeks of AB/FF-treatment in COPD are differential and the degree of change differs across domains of lung function, exercise capacity and PA. These results indicate that clinical response to LABD therapy is difficult to predict and is non-linear, and show doctors that it is important to look at multiple outcomes simultaneously when evaluating the clinical response to LABD therapy.
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| 2. |
- Aulitto, A., et al.
(author)
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Noise control in HVAC systems with ultra-thin low-frequency (UTLF) absorbers
- 2022
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In: Proceedings of ISMA 2022 - International Conference on Noise and Vibration Engineering and USD 2022 - International Conference on Uncertainty in Structural Dynamics. - : KU Leuven, Departement Werktuigkunde. ; , s. 365-374
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Conference paper (peer-reviewed)abstract
- In this work, the application of ultra-thin low frequency (UTLF) resonators to reduce low-frequency tonal noise components in HVAC systems is presented. A single UTLF absorber consists of a mass, a flexible membrane, a cavity, and a resistive layer. The resonator produces a near-perfect absorption in a narrow region around its resonance frequency. The proposed treatment consists of the addition, on one side of the HVAC duct, of an array of two kinds of UTLF resonators, tuned to two target frequencies. The acoustic performances of the system are mimicked in a three-dimensional numerical model, starting from a single resonator. The resonator impedance is tuned to the Cremer impedance of the duct by varying the design parameters to obtain optimal damping of the plane wave mode. The resonance frequency of the system is adjusted changing the mass and the depth of the cavity. Combining many resonators along the duct, one may achieve a high sound transmission loss in the target frequency due to the locally reactive behavior.
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