Análise das alterações da mecânica respiratória nos diferentes fenótipos na Doença Pulmonar Obstrutiva Crônica e sua relação com desempenho funcional

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by progressive and poorly reversible airflow obstruction, associated with a constant inflammatory process in the airways and lungs, the main cause of which is cigarette use. It is defined as chronic bronchitis (BC) and emphysema (ENF), and recently some patients with common features are defined as COPD phenotypes. BC is defined by the presence of cough with sputum for more than three months in two consecutive years. The ENF presents hyperinflation on chest X-ray, dry cough and dyspnea on slight exertion. Another group of patients with COPD have presented a positive test due to the use of bronchodilators (BD), asthma before the age of forty and a history of smoking, characterized as the ACOS phenotype. The spirometry test can identify COPD, however, the test requires effort and understanding from the individual. The Forced Oscillation Technique (FOT) assesses lung function non-invasively through spontaneous breathing, allowing a more detailed assessment of the respiratory system. This research aimed to evaluate, through FOT, changes in the respiratory mechanics of patients with COPD and their phenotypes, associating these changes with functional capacity. 83 volunteers were distributed into the following groups: 20 in the control group (CG), 23 in ENF, 20 in BC and 20 in ACOS. The patients underwent spirometry, FOT, manovacuometry, handgrip test and AVD-Glittre test. In spirometry, all phenotypes showed reduced FEV1/FVC values compared to the CG. ACOS showed a greater response to BD, confirming the asthma-COPD overlap. In the resistive parameters of the FOT, R4, R12, R4-R20 and R0 presented significant values when compared to the GC, in addition to the S parameter, which was more negative in this group. In the pre-BD comparison between ENF and ACOS in R4, R4-R20, R0 and S were also significant, as well as BC and ACOS in R4-R20, R0 and S. In the pre- and post-BD comparison, ENF and ACOS showed a significant decrease in R4, R12 and R0, while in R4-R20 and S, only ACOS showed a reduction. In FOT reactive parameters, more negative results of Xm were seen in the phenotypes, as well as lower Cdin values and higher fr, AXi and Z4 values compared to GC pre and post BD. The fr showed a reduction only in ACOS. No significant differences were seen after the use of BD in the BC group in any of the FOT resistive and reactive parameters. All phenotypes showed significant changes when compared with the predicted value in the handgrip and vacuum gauge tests. In the functional capacity test, there was a significant increase in the time taken by the phenotypes, when compared to the predicted values. Through these results, it was possible to observe that FOT can contribute to the identification of pathophysiological changes in the respiratory system of these patients. The functional capacity test demonstrated that the disease can impact quality of life, reducing ventilatory capacity. Furthermore, it was seen that the action of BD acts differently on each COPD phenotype, proving a greater need to improve the identification of these phenotypes in clinical practice.