Emphysema is a disease of the lung tissue caused by destruction of structures feeding the alveoli, in some cases owing to the action of alpha 1-antitrypsin deficiency. Smoking is one major cause of this destruction, which causes the small airways in the lungs to collapse during forced exhalation. As a result, airflow is impeded and air becomes trapped, just as in other obstructive lung diseases. Symptoms include shortness of breath on exertion, and an expanded chest.
People with this disease do not get enough oxygen and cannot remove carbon dioxide from their blood; they therefore exhibit dyspnea (shortness of breath). At first this occurs only during physical activity. Eventually it will occur after any physical exertion. Later the patient may be dyspneic all the time, even when relaxing. Because breathing is difficult, the patient must use accessory muscles to help them breathe; tachypnea (rapid breathing) may occur when they try to extend their exertion. They may have trouble coughing and lowered amounts of sputum. They may also lose weight.
The anteroposterior diameter of their chest may increase; this symptom is sometimes referred as "barrel chest." The patient may lean forward with arms extended or resting on something to help them breathe.
When lung auscultation and chest percussion is performed a hyperresonant sound is heard.
The patient may also exhibit symptoms of hypoxia-induced cyanosis, or the appearance of a blue to purplish discoloration of the skin, due to increased levels of deoxyhemoglobin in the blood.