The dynamics of respiratory muscle changes during the progression of chronic obstructive pulmonary disease.

BACKGROUND Pathological changes of the respiratory muscles (RM) during the development of chronic obstructive pulmonary disease (COPD) have not yet been studied in detail. OBJECTIVES The aim of the research was to assess RM status in COPD and the relationship between echodensitometric and morphological changes in the RM. MATERIAL AND METHODS The participants 152 male COPD patients were divided into three groups according to the severity of the disease: COPD₁ (mild), COPD₂ (moderate) and COPD₃ (severe). The status of the accessory RM in these groups was investigated using echodensitometry indices (echogenicity: IE; homogeneity: IH; and structural density: ISD) and the morphological material of the abdominal internal oblique muscle in 25 patients with COPD₁ and COPD₂. RESULTS Considerable differences among the COPD groups were revealed. In mild COPD a tendency toward increased homogeneity was detected (due to RM hypertrophy), while echogenicity results varied. IH and ISD decreased in moderate COPD, while IE was increased due to RM fatty infiltration and sclerosis (according to the morphological data). In severe COPD, IH and ISD rose again against a background of IE decrease. The presence of myolysis, sclerotic changes and contractures of myofibrils in the RM was significantly more frequently observed in COPD₁ and COPD₂ compared with the controls (where these features were rare). The sensitivity and specificity of the morphological and ultrasonic methods were similar in assessing atrophic and sclerotic RM changes, while their accuracy was lower in analyzing other morphological signs. CONCLUSIONS The echodensitometric parameters investigated reflect, in a complex way, different dynamics of degenerative RM processes during the progression of COPD.