Life-threatening check valve formation due to tracheobronchial aspergillosis.

A 12-year-old girl receiving chemotherapy for acute myeloid leukemia had a fever of unknown origin in spite of administration of micafungin. Her respiratory condition suddenly deteriorated. Her trachea was intubated, and positive pressure ventilation was initiated; however, her respiratory condition further deteriorated. Expiratory volume was considerably lower than inspiratory volume. Simultaneously, she developed severe hypotension and bradycardia, and tension pneumothorax was suspected. Emergent chest decompression was subsequently performed; however, her airway resistance was still high. Bronchoscopy was performed to remove a foreign body in the carina. Subsequently, her respiratory status improved. Histopathological examination revealed that the foreign body was a fibrinous blood clot mixed with fungal hyphae of Aspergillus niger . Life-threatening check valve formation due to tracheobronchial aspergillosis under positive-pressure ventilation may be rare; however, once it occurs, prompt establishment of an escape route for trapped air, such as thoracentesis, may be required.