A 55-year-old man is hospitalized with severe abdominal pain associated with nausea and vomiting. Laboratory studies show marked elevation of serum amylase and lipase. He has a history of heavy alcohol use. During hospitalization, his condition deteriorates and he develops severe respiratory distress. There are crackles bilaterally on physical examination and diffuse patchy infiltrates bilaterally on chest x-ray. The patient fails to improve with mechanical ventilation and 100% oxygen and dies 4 days later due to progressive respiratory failure. Which of the following autopsy findings is most likely in this patient?
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This patient with pancreatitis and subsequent respiratory failure likely has acute respiratory distress syndrome (ARDS). Pancreatitis is a major risk factor for ARDS as it results in the release of large amounts of inflammatory cytokines and pancreatic enzymes into the circulation, which leads to infiltration of neutrophils into the pulmonary interstitium and alveolar spaces. Diffuse injury to the alveolar epithelium and pulmonary microvascular endothelium results in a leaky alveolocapillary membrane and significant pulmonary edema.
ARDS is typically characterized by progressive hypoxemia refractory to oxygen therapy and diffuse interstitial edema in the absence of cardiogenic causes. During the first 1-6 days, interstitial and intraalveolar edema, inflammation, and fibrin deposition cause the alveoli to become lined with waxy hyaline membranes. These membranes consist of fibrin exudate and inspissated protein-rich edema fluid mixed with the remnants of necrotic epithelial cells.
(Choice B) If this patient's rapid-onset dyspnea were due to cardiogenic pulmonary edema, as can occur in decompensated heart failure, or if the patient had chronic heart failure due to alcohol use, chest x-ray would likely reveal cardiomegaly.
(Choice C) This patient is at risk of aspiration; however, aspiration pneumonia due to anaerobic bacteria commonly presents more indolently and is more likely to show an abscess or empyema than diffuse patchy opacities on chest x-ray.
(Choice D) Although disseminated intravascular coagulation and ARDS can result in alveolar hemorrhage, the absence of hemoptysis makes this choice less likely.
(Choice E) Lung hyperinflation may be seen in emphysema, which is a chronic, destructive enlargement of the air spaces distal to the terminal bronchiole.
Educational objective:
Pancreatitis is a major risk factor for acute respiratory distress syndrome as it results in the release of large amounts of inflammatory cytokines and pancreatic enzymes, which leads to activation of neutrophils in the alveolar tissues. During the initial phase, interstitial and intraalveolar edema, inflammation, and fibrin deposition cause the alveoli to become lined with waxy hyaline membranes.