Definition

Hypoxic ischemic encephalopathy (HIE) is injury to the brain because of a lack of oxygen. The injury can lead to a range of disabilities. A severe injury can lead to death.

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Causes

Brain cells can start to die after 4 minutes without oxygen. This may happen because of poor blood flow to the brain or low levels of oxygen in the blood. In a newborn, it is often caused by a problem at birth. Some HIE in newborns may be caused by a disease or illness.

Risk Factors

Factors before or during labor and delivery that increase the risk of HIE include:

• In the mother:
  • Ruptured uterus (womb)
  • Cardiovascular collapse with respiratory failure
  • Preeclampsia—dangerously high blood pressure
  • Seizures
  • Trauma
  • Carbon monoxide poisoning
• In the baby:
  • Separation of the placenta from the uterus
  • Cord prolapse—when the umbilical cord exits the uterus with or before the baby
  • Shoulder dystocia—when the baby’s shoulders get stuck in the mother’s body
  • Exposure to extreme heat

Symptoms

Symptoms can vary from mild to severe. They may include:

• Signs of brain injury, such as
  • Muscle tone that seems loose or floppy
  • Reduced alertness
  • Seizures
• Trouble breathing
• Blue colored skin or lips

Some symptoms such as learning or development delays may not appear until the child is older.

Diagnosis

Babies are observed after birth. An APGAR score will check signs of health. A baby with HIE will have lower APGAR scores. An MRI scan may be done. This will help to show or track damaged areas of the brain. The doctor will use these results as well as details about the birth to diagnose HIE.

Other tests may be needed if a cause is not clear. This may include blood tests.

Treatment

Immediate care will make sure the brain is getting enough oxygen. Support may include:

• Treatment to support the heart, control blood pressure, and improve blood flow
• Mechanical ventilation—if baby needs help breathing
• Seizure medicine—to control seizures
• Cooling beds or hats—lower body temperature may decrease damage

The long-term effects of HIE will depend on the area of the brain and amount of damage. Some may have severe disabilities. Others may be mild and not apparent until the baby is older. Early intervention is important. Supportive care will help to minimize the effect of the injury. Assistive devices, exercises, and learning aids may be needed.

Prevention

In most cases, HIE is sudden and cannot be prevented.