Systemic effects of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is associated with important extrapulmonary, or systemic, effects. There is systemic as well as pulmonary inflammation in COPD and this, together with systemic oxidative stress, contributes to their development. Skeletal muscle dysfunction contributes to exercise limitation. There is a loss of muscle mass and a reduction in the proportion of type 1 fibers. Sedentarism, hypoxia, corticosteroid therapy, nutritional depletion and systemic inflammation may contribute to its development. Weight loss is another important effect. It is associated with a worse prognosis, which changes with therapy and may be due to reductions in calorie intake, changes in intermediate metabolism and effects of systemic inflammation. Cardiovascular disease is a frequent cause of death in COPD and coronary artery disease, left ventricular failure and arrhythmias are systemic effects of COPD, as well as comorbidities sharing a common etiology. Exacerbations of COPD may increase the risk of coronary events by increasing the level of systemic inflammation. Osteoporosis is more common in COPD (even after adjusting for corticosteroid usage) and may be due to a combination of inactivity and the effects of systemic inflammation. COPD is also associated with systemic endothelial dysfunction and CNS abnormalities (including depression), which may also be due to the effects of systemic inflammation. These systemic effects respond to COPD treatments, including pulmonary rehabilitation, nutritional supplementation and inhaled corticosteroids, as well as specific drugs, such as bisphosphonates or diuretics. There is growing evidence that novel approaches, such as the use of statins, may also be of value.