What is the cause of neonatal pulmonary hemorrhage?

The impact of neonatal pulmonary hemorrhage is definitely quite large, so we should pay attention to understand the cause, especially premature babies or newborns with low birth weight, who are prone to symptoms of pulmonary hemorrhage, or may be manifestations of lung disease.

1. Causes and pathogenesis of neonatal pulmonary hemorrhage :

The cause of neonatal pulmonary hemorrhage has not yet been fully elucidated, and it is more common in premature and low-birth-weight infants. There are more males than females, about 1.

5～3.6:1. Pulmonary hemorrhage manifests as extreme pulmonary edema. Some data show that neonatal pulmonary hemorrhage is related to the following factors: asphyxia and hypoxia, infection, sepsis, hypothermia, congestive heart failure, neonatal hyperviscosity syndrome, Rh hemolysis, traumatic tracheal and bronchial erosion, and some iatrogenic factors such as the use of alkaline drugs during resuscitation, oxygen poisoning, excessive peak pressure of mechanical ventilation, and the use of surfactants to treat lung diseases. Among them, asphyxia/hypoxia is the most common cause of neonatal pulmonary hemorrhage on the first day after birth, while infection is an important cause of pulmonary hemorrhage 3 to 4 days after birth. Pulmonary hemorrhage caused by the use of pulmonary surfactant is also a cause worthy of attention.

2. Neonatal pulmonary edema is commonly caused by increased pulmonary capillary pressure, which causes an increase in interstitial fluid and finally enters the alveoli through the endothelial pores. Initially, only albumin molecules leak out. When the endothelial pores enlarge, IgG, IgM, fibrinogen, and red blood cells also leak out. However, the amount of bleeding is generally less, and the hematocrit decreases by less than 10%.

3 Pathology of neonatal pulmonary hemorrhage:

The main lesions are in the lungs, and may also be combined with bleeding in other organs, with intracranial hemorrhage being the most common. The lungs can be seen to increase in size with large red hemorrhage areas. It is common for more than two lobes of the lung to be affected. In severe cases, the entire lung is filled with blood and has a firm texture. A large amount of blood will flow out when the dark red hemorrhage area is cut open. Under the microscope, there are a large number of blood components in the alveoli in the hemorrhage area, some of which are degenerated red blood cells with unclear appearance. There is often blood cell infiltration in the interstitium. In severe cases, the original lung structure cannot be seen, and there is usually no inflammatory cell infiltration. Immunofluorescence examination showed IgG and C3 deposition in lung tissue. Electron microscopy revealed dense masses in the capillary basement membrane, which seemed to be antigen-antibody complexes.

4. In most cases of pulmonary hemorrhage, the hematocrit of bloody secretions flowing out of the airways is significantly lower than that of venous blood, and pathologically, vascular changes are mainly in the capillaries. Therefore, it is believed that neonatal pulmonary hemorrhage is secondary to pulmonary edema, caused by a sharp increase in pulmonary capillary pressure. In some cases, the hematocrit of bloody secretions flowing out of the airways is similar to that of red blood cells in venous blood. Pathologically, inflammation can directly damage blood vessels, indicating that pulmonary hemorrhage in some patients is caused by direct damage to blood vessels.