PHYSICAL WEAKNESS AS COPD PHENOTYPE

Chronic obstructive pulmonary disease (COPD) is an important cause of disability and premature death. The Global Strategy for the Diagnosis, Management and Prevention of COPD (GOLD) gives much attention to pulmonary rehabilitation programs including training of the muscles of the upper extremities and of respiratory muscles, which, in turn, permits to reliably reduce severity of clinical manifestations, to improve the quality of life, reduce the need for specialized medical care including outpatient visits to a doctor and the rate of exacerbations and hospitalizations for the given disease. One of the main problems of patients with this pathology is the syndrome of physical weakness. In these patients, disorders occur both in respiratory muscles and in muscles of the extremities, which reduces tolerance to physical exercise with the result of a considerable impairment of the quality of life. Muscles of the lower extremities suffer to a higher extent than respiratory muscles and muscles of the upper extremities. According to foreign data, the cause of physical weakness is skeletal muscle dysfunction which leads not only to exercise intolerance, but is also a predictor of increased mortality in COPD. Factors that contribute to muscle dysfunction are similar to those observed in a stable course of COPD: a significant role of nutritive support, hypercapnia, hypoxemia, electrolyte disorders, systemic inflammation. These factors may play a role of a triggering mechanism for a cascade of local inflammatory reactions and metabolic disorders that may induce different clinical effects including development of muscle dysfunction. At the moment, the problem of physical weakness as a consequence of muscle dysfunction in COPD deserves special study in order to effectively manage patients with this pathology in real clinical practice. Given the importance of the problem, a number of researchers have identified a separate phenotype of physical weakness in COPD. Identification of molecular mechanisms participating in muscle dysfunction, in loss of muscle mass and in disorders in anabolism will permit to elaborate new therapeutic goals in future.