Oscilometria respiratória, modelamento e capacidade funcional em pacientes com doença pulmonar obstrutiva crônica

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by persistent progressive airflow limitation associated with an inflammatory response in the airways and lungs. Functional abnormalities associated with COPD cause dyspnea on exertion and reduced exercise capacity. The AVD–Glittre test is an effective, easy-to-apply, valid and reliable test to assess functional capacity in COPD. The loss of muscle strength is directly linked to physical performance, mobility and functionality in these patients. The handgrip test proved to be valid in the assessment of strength and is considered cheap and simple. Respiratory oscillometry evaluates the mechanical properties of the respiratory system, through impedance analysis, in a non-invasive way and requiring little cooperation. In this context, the present work was divided into two phases. The objectives of phase one were to analyze the potential of respiratory oscillometry combined with respiratory models in the different classifications of COPD and to determine the best parameters for the diagnosis of different stages of the disease. The objectives of phase two were to investigate the association between oscillometric parameters and changes in ADL–Glittre and the handgrip test and to assess the accuracy of oscillometric measurements as a predictor of abnormal functional capacity in COPD. Diagnostic accuracy analyzes provided evidence that hysteresivity allowed high accuracy identification in patients with mild alterations. Similar analyzes in moderate and severely ill patient groups showed that peripheral resistance provided the most accurate parameter (AUC=0.898 and 0.998, respectively), whereas in very severe patients, traditional and model-derived parameters were able to achieve high diagnostic accuracy ( area under the curve, AUC>0.9). The second phase of the study initially showed that individuals with abnormal functional capacity had higher values for resistance (p<0.05), reactance area (p<0.01), impedance modulus (Z4, p<0.05) and dynamic compliance (Cdyn, p<0.05) were reduced when compared to individuals with normal functional capacity. This resulted in significant and consistent correlations between the resistive oscillometric parameters (R=−0.43), Cdin (R=−0.40), Ax (R=0.42) and Z4 (R=0.41) with the exercise performance. Furthermore, the effects of exercise limitation on COPD were adequately predicted (AUC), with R4-R20 (AUC=0.779) and Ax (AUC=0.752) as the best parameters. It is concluded that in phase one, respiratory oscillometry combined with the models used presented adequate diagnostic accuracy in the different classifications of COPD. In phase two, the main conclusion was that oscillometric parameters are associated with abnormal exercise performance in COPD and may help to predict the decline in functional performance in these patients