LearningRadiology - Pneumomediastinum

Pneumomediastinum

(Mediastinal Emphysema)

Rare in adults (except in ICU patients) and most common in newborns

ETIOLOGIES

Spontaneous – most common mechanism in kids and adults

Pathophysiology involves increased intralveolar pressure such as from cough or vomiting which ruptures alveolus, air tracks back along blood vessels to mediastinum

Accompanying pneumothorax common in neonates

When air builds up in mediastinum and can’t pass into the neck (especially in kids) this produces mediastinal air block which can reduce flow of blood in great vessels

In adults, the air in mediastinum usually progresses into the neck and the subcutaneous tissue

· Traumatic – 2° closed chest trauma

o Same mechanism as spontaneous

· Rupture of the esophagus – Boerhavve's Syndrome

o May occur with vomiting, labor, severe asthmatic attacks and strenuous exercise (each of these can produce pneumomediastinum without rupturing the esophagus)

o LEFT, POSTEROLATERAL WALL, DISTAL 8 CM

X-ray – combination of pneumomediastinum and left pleural effusion is very suggestive; continuous diaphragm sign

Symptoms – infants – none.
Adults – chest pain (retrosternal) radiating down both arms aggravated by respiration and swallowing; Hamman’s sign – crunching sound heard over the apex of the heart with cardiac cycle

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