Erratic control of breathing during exercise in patients with systemic lupus erythematosus: a pilot-study

PURPOSE: The aim of this study was to provide a comprehensive evaluation of the pattern and timing of breathing during incremental exercise in a sample of women living with systemic lupus erythematosus (SLE). METHODS: In this cross-sectional study, 20 women with SLE without pulmonary involvement were compared with 20 gender-, body mass index- (BMI), and age-matched healthy individuals. By using a cardiopulmonary incremental exercise test, the following parameters were assessed: tidal volume (VT); breathing frequency (BF); total respiratory time (TOT); inspiratory time (TI); expiratory time (TE); inspiratory time to total time (TI/TOT); mean inspiratory flow (VT/TI); ventilatory equivalent for carbon dioxide (VE/VCO2) and end-tidal carbon dioxide pressure (PETCO2). RESULTS: BF and BF/VT were significantly higher in patients with SLE versus controls, whereas VT, TE, TI and TOT were significantly lower in the former group ( p<0.05). Additionally, patients with SLE presented higher VE/VCO2 and lower PETCO2 than controls ( p<0.05), suggesting a ventilatory inefficiency. CONCLUSION: We reported compelling evidence of abnormal pattern and timing of breathing during incremental exercise in SLE. Considering that an erratic control of breathing may play an important role in exercise intolerance and fatigue, respiratory exercises emerge as a potential treatment for these symptoms in patients with SLE.