Impact of metabolic and ventilatory demand during activities of daily living on oxygen saturation and dyspnea

Background: COPD patients have poor quality of life and may have limitation in their activities of daily living (ADL). ADL limitations could be manifested as oxygen desaturation and progressive dyspnea, furthermore activities involving unsupported upper limbs movements leads to increase minute ventilation and to drop metabolic and ventilatory reserves. Aim: Verify metabolic and ventilatory demand and identify if these demands could explain an oxygen saturation and dyspnea in three different ADL. Methods: A cross-sectional study was conducted. Twenty-eight patients with COPD (FEV1=50,6±15,3, 69,3±7,2yrs) performed a symptom-limited cardiopulmonary test and simulated three ADL: showering (ADL1); lifting containers above scapular girdle (ADL2) and lowering pots below pelvic girdle (ADL3) in appropriate laboratory associated with ventilation and gas exchange analysis. Results: Ventilatory demand was higher in ADL3 (50,54±27,90) compared to ADL1 (46,24±24,9). Patients achieved values above 80% (ADL1: 87,4±48,8; ADL2:90,2±34,2; ADL3: 85,2±36,9) of their metabolic demand with no significant differences between activities. There was moderate correlation between SpO2 and ADL1 (r=-0,44), ADL2 (r=-041) and ADL3 (r=-0,46), and an oxygen desaturation in ADL3 can be explain in 21% an increase in metabolic demand. Conclusion: Activities associated to upper limbs movements with flexion and trunk rotation lead to greater ventilation and ventilatory demand. In all ADL assessed patients achieve higher values of their metabolic demand and desaturation is a factor that may reflect in metabolic demand variation during ADL simulation.