Many of the signs of COPD are caused by the body's attempt to compensate for a damaged respiratory system. That is, they are consequences of the anatomical changes caused by the disease: barrel chest, pursed-lip breathing, productive cough, and cyanosis.
One telling sign of COPD is the change in the shape of the chest, known as barrel chest. When the lungs become enlarged, the diaphragm is displaced downward and is unable to contract efficiently. Furthermore, the chest wall is enlarged, making accessory breathing muscles (muscles in the neck, upper chest, and between the ribs) less efficient as well. These changes contribute to shortness of breath. This becomes apparent when a person with COPD tries do something with the arms raised above the head, such as changing a light bulb in a ceiling fixture, and becomes short of breath.
To compensate, a person with COPD often sits leaning forward with their arms supported on a surface in front of them or on their knees. This stabilizes the upper chest and shoulders and allows them to use accessory respiratory muscles more efficiently.
Because airflow out of the lungs becomes limited, exhalation takes longer. Because the alveoli lose their elasticity, one tries to shorten the time needed for exhalation by forcefully exhaling. Unfortunately, forced exhalation increases pressure on the lungs and causes structurally weakened airways to collapse. To prevent airways from closing during forced exhalation, pursed-lip breathing is used: The lips are narrowed together, which slows exhalation at the mouth. This keeps positive pressure in the airways, thus preventing their collapse and allowing some forced exhalation.
A productive cough is caused by inflammation and excessive amounts of mucus in the airways. Coughing becomes less effective because of obstructed airflow.
People who have a poor supply of oxygen usually have a bluish tinge to their skin, lips, and nailbeds, called cyanosis.