In intubated neonates, airway trauma from tube itself or from suction catheters is often source of bleeding. Usually this is mild and self limited, but cases of severe airway bleeding have been reported. In a series of 12 cases of fatal massive pulmonary hemorrhage in neonates left ventricular failure, secondary to congenital lesions, severe RDS, sepsis or other causes, was the precipitating factor.
Blood actually represents severe pulmonary edema with extravasation of red cells into airspaces.
If hematocrit and protein content of blood within airspaces is compared with that seen in peripheral blood, composition is different. Kernicteurs, severe intracranial hemorrhage and hypothermia have also been associated as leading to pulmonary hemorrhage. Mechanism is felt to be secondary to severe hypoxia and increased left ventricular end-diastolic pressure. Bacterial pneumonia and sepsis with DIC can also trigger massive pulmonary hemorrhage from direct tissue injury and leaking of blood into alveolar spaces. Hyperammonemia can induce intrapulmonary bleeding that is felt to be related to direct toxicity on the pulmonary vascular endothelium.