Skeletal muscle dysfunction and changes in body composition are important extra-pulmonary manifestations of chronic obstructive pulmonary disease (COPD) that occur in all stages of disease and are associated with poor outcome. In patients with COPD, bioelectrical impedance analysis (BIA) has usually been used to estimate fat-free mass (FFM) and body composition through predictive equations. Very few studies had focused on raw BIA data. The aim of this study is first describe the measurement of phase angle in patients with with acute exacerbation and second to determine the validity of phase angle in this group by assessing its relationship with established markers of function, disease severity and prognosis.
