Bloody Bronchial Cast Formation Due to Alveolar Hemorrhage Associated with H1N1 Influenza Infection

A previously healthy 55-year-old man with H1N1 influenza A presented with severe respiratory failure and cardiac arrest. Following the return of spontaneous circulation, venovenous extracorporeal membrane oxygenation was required to maintain oxygenation. On day 2, bronchoscopy revealed a bloody bronchial cast obstructing the right main bronchus. A pathological examination revealed that it was composed of intrabronchial and intra-alveolar hemorrhagic tissue. Unfortunately, the patient died due to severe brain ischemia; a subsequent autopsy revealed marked alveolar hemorrhage. It is possible that anticoagulant therapy, alveolar collapse, and neuromuscular blocking agents provoked cast development in this case.