What is it?
Chronic obstructive pulmonary disease (COPD) is a chronic and slowly progressive disorder characterized by an airway obstruction. 
COPD leads to chronic airflow obstruction, which is defined as a persistent decrease in the rate of airflow from the lungs when the person breathes out. This airflow obstruction is partially reversible with treatment. COPD includes a cough that produces sputum repeatedly during two successive years that involves airflow obstruction (chronic obstructive bronchitis). In COPD, there is a widespread and irreversible destruction of the alveolar walls, and enlargement of the alveoli. The bronchioles, the small airways, are normally held open because of their attachment to the alveolar walls. If the alveolar walls are destructed, the bronchioles collapse, causing permanent airflow. On the other hand, the enlargement of the alveoli, the larger airways, increase their secretion of mucus, causing inflammation and, therefore, further obstructing the airflow. The airflow obstruction of COPD causes air to become trapped in the lungs after a full exhalation, increasing the effort required to breathe. Also, the number of capillaries decrease, decreasing the exchange of the oxygen and carbon-dioxide between the alveoli and the blood, which can cause Pulmonary Hipertension. 
Various factors are associated with the onset of the disease, including cigarette smoking or working in an environment with poor air quality, polluted by chemical fumes or dust. Exposure to air pollution and to smoke from nearby smokers (passive smoke exposure). 
People with the condition often have symptoms of cough, overproduction of sputum and dyspnea (shortness of breath) with increasing frequency of cute episodes such as respiratory infection. Due to the chronic and progressive nature of the disease, most of the lung function impairments are permanent, although some might be reversible. 
Patients with mild COPD may have minimal symptoms, such as occasional morning cough, recurrent respiratory infection, or shortness of breath after a vigorous effort. As the disease progresses, coughing and sputum production may increase, leading to shortness of breath on moderate physical tasks. At the last stage, patients often experience frequent acute episodes with progressive chronic breathlessness or respiratory complications. 
As a result of the symptoms mentioned above, persons with COPD, who are often elderly, face increasingly severe respiratory symptoms across time. These symptoms increasingly limit people’s participation in various activities of daily living (ADL) .
At the early stage of the disease, people might have difficulties in stair climbing and doing outdoor activities. As the disease progresses people may have problems doing activities requiring minimal physical tasks, such as dressing, feeding and grooming. They might experience significant breathlessness even at rest. As a result, over time, people with the disease experience a decline in their physical ability and may feel they have less and less personal control over activities that once seemed basic and easy .
In addition to dyspnea, coughing, wheezing, sputum production, recurrent respiratory infection, deconditioning, muscle weakness, weight loss and malnutrition. Emotional problems such as depression, anxiety and social isolation can also be observed. 
 Chan, S. C. C. (2004). Chronic obstructive pulmonary disease and engagement in occupation. American Journal of Occupational Therapy, 58, 408–415
 Gosselink, R. et al. (2008). Clinical Practice Guideline for Physical Therapy in patients with COPD – Practice Guideline. KNGF Clinical Practice Guideline, 118 (4)
 Wise, R.A. (2007). Chronic Obstructive Pulmonary Disease. http://www.merckmanuals.com/home/sec04/ch045/ch045a.html