Pneumomediastinum Health Dictionary

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Pneumomediastinum: From 1 Different Sources

n. air in the mediastinum visible on chest X-ray. It can be a complication of surgical *emphysema due to pneumothorax, but the air can originate from the upper airways or the upper gastrointestinal tract. A rare cause is gas-forming organisms. See Hamman’s sign.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Emphysema

n. air in the tissues. In pulmonary emphysema the air sacs (*alveoli) of the lungs are enlarged and damaged, which reduces the surface area for the exchange of oxygen and carbon dioxide. Severe emphysema causes breathlessness, which is made worse by infections. There is no specific treatment, and the patient may become dependent on oxygen. The mechanism by which emphysema develops is not understood, although it is known to be particularly common in men in Britain and is associated with chronic bronchitis, smoking, and advancing age. See also chronic obstructive pulmonary disease.

In surgical emphysema air may escape into the tissues of the chest and neck from leaks in the lungs or oesophagus; occasionally air escapes into other tissues during surgery, and bacteria may form gas in soft tissues. The presence of gas or air gives the affected tissues a characteristic crackling feeling to the touch, and it may be visible on X-rays. When air moves to the mediastinum the condition is known as *pneumomediastinum. It is easily absorbed once the leak or production is stopped.... emphysema

Hamman’s Sign

a crunching sound synchronous with the heartbeat heard with a stethoscope in 45–50% of patients with *pneumomediastinum. [L. V. Hamman (1877–1946), US physician]... hamman’s sign

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