Background and objective: The purpose of this study was to evaluate on a prospective fashion the effects of clinical relapses of chronic obstructive pulmonary disease (COPD) on both peripheral and respiratory skeletal muscle functions.
Patients and method: We included 49 patients (males, 63  years) who were assigned to three cohorts: a) COPD patients who were hospitalized in a conventional ward because of a relapse of their disease; b) patients hospitalized in conventional wards because of another lung disease or a pulmonary nodule; and c) COPD patients whose disease was stabilized (outpatients). Sequential measurements were made by means of anthropometry, serum biochemistry and body bioimpedance (BIA). In COPD patients with a disease relapse, we assessed changes in the function of peripheral muscles [force (Fhand) and resistance (Tlimhand) of hands], inspiratory muscles (PImax) and respiratory muscles (PEmax).
Results: Patients were evaluated during a 6  days period. Patients with a COPD relapse displayed a global and progressive functional muscle impairment, which was expressed as a decrease of PEmax (17 %), F hand-D (6 %), F hand-ND (7 %), Tlim hand-D (28 %) and Tlim hand-ND (23 %). These changes showed a linear trend. BIA exhibited a loss of lean mass (7 %, p < 0.05) which would have been unnoticeable if only the body weight was quantified. Pneumonia cases showed similar changes in BIA. On the other hand, the cohort of patients with stable COPD did not have changes in both muscle function and BIA.
Conclusions: COPD exacerbation is associated with an acute and global impairment of the function of respiratory and peripheral skeletal muscles. It is possible that these changes are related to an acute loss of muscular mass (proteolysis). This muscle dysfunction is not detected if only the inspiratory muscular function is evaluated--possibly because of the coexistence of transitory mechanic factors.