What is the cause of neonatal hypoxic encephalopathy?

Neonatal hypoxic encephalopathy poses a threat to the growth and health of newborns. Common causes include maternal factors, such as pregnancy-induced hypertension syndrome, or heart and lung diseases, and severe anemia can all affect these problems.

1. Etiology and pathology

Perinatal asphyxia is the main cause of this disease. Anything that causes obstruction of blood circulation and gas exchange between the mother and fetus, resulting in a decrease in blood oxygen concentration, can cause suffocation. 50% are caused by intrauterine asphyxia; 40% are caused by asphyxia during delivery; and 10% are caused by congenital diseases.

(1) Maternal factors: pregnancy-induced hypertension, heavy bleeding, cardiopulmonary disease, severe anemia or shock, etc.

(2) Placental abnormalities: placental abruption, placenta previa, placental dysfunction or structural abnormalities, etc.

(3) Fetal factors: intrauterine growth retardation, premature birth, post-term birth, congenital malformations, etc.

(4) Umbilical cord blood blockage: such as umbilical cord prolapse, compression, knotting or winding around the neck.

(5) Factors during delivery: such as delayed labor, precipitous labor, abnormal fetal position, surgery or use of anesthetics, etc.

(6) Neonatal diseases: such as recurrent apnea, RDS, bradycardia, severe heart failure, shock and polycythemia.

2. Pathophysiological and Pathological Anatomical Changes

The brain's energy source is different from that of other organs, and almost all of it comes from the oxidation of glucose. The brain metabolism of newborns is the most active, and the brain's oxygen consumption is half of the body's oxygen consumption. There is very little glycogen in the brain, and glucose and oxygen are entirely supplied by the cerebral blood circulation. Hypoxia first affects the brain. The brain undergoes the following four changes when it is deprived of oxygen:

1. Energy metabolism disorder: When hypoxic, the fermentation of brain tissue increases 5-10 times, causing metabolic acidosis.

2. Ventilatory dysfunction: CO2 retention increases Paco2 and causes respiratory acidosis.

3. Due to anaerobic metabolism, the production of ATP in the brain is significantly reduced. On the one hand, the energy source is insufficient, the oxidative metabolism process in the brain is damaged, and a large number of neurons die. On the other hand, it causes sodium pump dysfunction, increases sodium chloride in brain cells, and causes intracellular edema.

4. Hypoxia and reduced blood flow in the cerebral microvessels cause cerebral ischemia, and increase in vascular permeability leads to vasogenic cerebral edema, which further causes cerebral ischemia and subsequent brain necrosis.