Objective: To evaluate the influence of chronic heart failure (CHF) on resting lung volumes in patients with COPD, i.e., inspiratory fraction—inspiratory capacity (IC)/TLC— and relative inspiratory reserve—[1 − (end-inspiratory lung volume/TLC)]. Methods: This was a prospective study involving 56 patients with COPD—24 (23 males/1 female) with COPD+CHF and 32 (28 males/4 females) with COPD only—who, after careful clinical stabilization, underwent spirometry (with forced and slow maneuvers) and whole-body plethysmography. Results: Although FEV1, as well as the FEV1/FVC and FEV1/slow vital capacity ratios, were higher in the COPD+CHF group than in the COPD group, all major “static” volumes—RV, functional residual capacity (FRC), and TLC—were lower in the former group (p < 0.05). T here was a greater reduction in FRC than in RV, resulting in the expiratory reserve volume being lower in the COPD+CHF group than in the COPD group. There were relatively proportional reductions in FRC and TLC in the two groups; therefore, IC was also comparable. Consequently, the inspiratory fraction was higher in the COPD+CHF group than in the COPD group (0.42 ± 0.10 vs. 0.36 ± 0.10; p < 0.05). Although the tidal volume/IC ratio was higher in the COPD+CHF group, the relative inspiratory reserve was remarkably similar between the two groups (0.35 ± 0.09 vs. 0.44 ± 0.14; p < 0.05). Conclusions: Despite the restrictive effects of CHF, patients with COPD+CHF have relatively higher inspiratory limits (a greater inspiratory fraction). However, those patients use only a part of those limits, probably in order to avoid critical reductions in inspiratory reserve and increases in elastic recoil.
CITATION STYLE
de Souza, A. S., Sperandio, P. A., Mazzuco, A., Alencar, M. C., Arbex, F. F., de Oliveira, M. F., … Neder, J. A. (2016). Influence of heart failure on resting lung volumes in patients with COPD. Jornal Brasileiro de Pneumologia, 42(4), 273–278. https://doi.org/10.1590/S1806-37562015000000290
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