Utilização da capacidade de exercício como preditor de morbidade em pacientes com fibrose cística

Abstract

Introduction: Cystic fibrosis (CF) is a disease that affects multiple organs and systems and generates the accumulation of secretions in the airways, causing chronic respiratory infections. This fact contributes to the increase in pulmonary exacerbations and days of hospitalization. Treatment includes several therapies and exercise is part of the clinical recommendations for better prognosis evolution. Objective: (i) to evaluate, through a systematic review, whether field tests have good associations with maximum oxygen consumption (VO2peak) in individuals with CF, (ii) to evaluate the association of aerobic fitness, evaluated by variables of the ventilatory threshold from cardiopulmonary exercise testing (CPET), with the risk of exacerbation in individuals with CF. Methods: This thesis was divided into 2 studies. In study 1, a systematic review was carried out in which a search was performed in the PubMed, Embase, LILACS, SciELO and PEDro databases. Studies that presented associations between field tests and VO2peak, and also those that presented predictive equations of VO2peak through field tests were included. Study 2 consisted of a retrospective cohort, in which patients aged over six years were included. CPET and spirometry data were collected. In addition, a 4-year follow-up was evaluated and morbidity data recorded. Results: Study 1 showed that the equations derived from the shuttle test (ST) showed strong correlations with VO2peak (r=0.79 to 0.95). The six-minute walking test showed moderate associations with VO2peak in participants with moderate disease severity (r=0.53 to 0.65). Furthermore, patients with lower maximal heart rate in the threeminute step test tended to have a higher percentage of predicted VO2peak (r=-0.40), and the one-minute sit-to-stand test showed moderate correlations between VO2peak and the number of repetitions (r=0.52 to 0.66). In article 2, 20 patients were included (mean age 16±5.4 years). Univariate regression showed that lung function (forced expiratory volume in one second, FEV1: Cox HR 0.97; p=0.028 and forced expiratory flow between 25% and 75% of vital capacity, FEF25-75: Cox HR 0.98; p=0.036) and aerobic fitness (oxygen consumption - VO2 at the ventilatory threshold: Cox HR 0.94; p=0.01 and ventilatory equivalent for carbon dioxide - VE/VCO2 at the ventilatory threshold: Cox HR 1.13; p=0.049) were associated with risk of exacerbation. In the multivariate model, the only significant variable was VO2 at the ventilatory threshold (%max) (Cox HR 0.92; p=0.01). Individuals who exacerbated had significantly lower VO2 values (%max) at the ventilatory threshold (p=0.050), as well as a higher ventilatory equivalent for oxygen consumption - VE/VO2 (p=0.040) and VE/VCO2 (p=0.037) at the ventilatory threshold. Time to first exacerbation was significantly correlated with VO2 at the ventilatory threshold (r=0.50; p=0.02), VE/VO2 (r=-0.48; p=0.02) and VE/VCO2 (r=-0.50; p=0.02). Conclusion: The results of the systematic review suggest that field tests are correlated with oxygen consumption assessed by CPET, although only the ST seems to be valid as a predictor of VO2peak in patients with CF. In addition, the cohort study showed that CPET variables at the ventilatory threshold are associated with the occurrence of exacerbations and that VO2 (%max) at the ventilatory threshold can be a predictor of exacerbation in patients with CF.