A 66 yo M w/ history of prior duodenal perforation s/p numerous graham patch repairs and prior endovascular aortic repair presents to the ED w/ altered mental status and hypotension w/ a SBP in 60s. He is emergently intubated. RUSH exam is done and free fluid is noted in the abdomen. His post-intubation CXR is shown below. What's the diagnosis? (scroll down for answer)

Answer: Pneumoperitoneum

• Etiology
• Trauma: local via iatrogenic (cautery, instrumentation), blunt, penetrating
• Bowel obstruction: occurs proximal to obstruction due to increase in pressure on bowel wall (leads to ischemic necrosis, wall breakdown)
• Spontaneous: medication related, connective tissue disorders, inflammation
• Free air in peritoneum --> leads to decreased diaphragmatic excursion --> respiratory distress
• Watch for abdominal compartment syndrome as well as mediastinal air/crepitus
• Additional imaging:  CT can identify location of perforation 
• Initial ED management: IVF, broad spectrum antibiotics, NPO, immediate surgical consult
• surgery may decide directly to OR for exploration/drainage vs CT imaging
• Dispo: ICU

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