Differences in Respiratory Mechanics in Emphysema and Chronic Bronchitis Evaluated by Forced Oscillations

Chronic obstructive pulmonary disease (COPD) includes emphysema and chronic bronchitis. These different phenotypes may introduce different characteristics that need to be known to improve COPD treatment. Thus, the objective of this study is to identify through the forced oscillations technique (FOT) the differences in respiratory mechanics in these phenotypes before and after bronchodilator (BD) use. In this cross-sectional study, the results of a sample of 30 volunteers are presented, being divided into control group (CG = 10), emphysema (ENF = 10) and chronic bronchitis (CB = 10). Spirometric and plethysmographic exams were also performed. Before BD, resistances were higher in CB than in controls, a fact that did not occur in a similar comparison in patients with ENF. It were observed increased resistances and impedance modulus in CB in comparison with ENF after BD use, which may be explained by secretion mobilization due to maximum expiratory effort during spirometry. These results provide evidence that the presence of CB results in greater respiratory work than that resulting from the presence of ENF. This new information on COPD phenotypes can contribute to improving the therapeutic strategies used, and consequently, to the assistance offered to these patients. The presented results also provide evidence that FOT is a useful tool in evaluation of the COPD phenotypes, adequately describing the disease's physiology and clinical practice.