Hypoxic Ischemic Encephalopathy (HIE) is a type of brain damage that occurs when an infant’s brain doesn’t receive enough oxygen and blood. It is a dangerous condition that requires immediate medical intervention. Per the Florida Neonatal Neurologic Network, HIE affects 20 out of every 1000 full term births; the incidence rate in premature babies is 60% of all live births.
What is HIE?
HIE is a brain dysfunction caused by a reduction in the supply of oxygen to the brain and other organs (hypoxia), compounded by low blood flow to vital organs (ischemia). Encephalopathy refers to any condition that results from reduced blood and oxygen supply to the brain.
Since this is considered a brain injury, the time of the oxygen deprivation generally relates to the perinatal period, just before and just after delivery.
HIE caused by asphyxia is the leading cause of infant fatalities in the United States, as well as the primary source of severe impairments.
What Are the Symptoms of HIE?
There are a number of symptoms associated with HIE, including:
- Meconium-stained amniotic fluid
- Low heart rate
- Poor muscle tone
- Weak breathing or no breathing at all
- Bluish or pale skin color
- Excessive acid in the blood
Tests to confirm HIE after symptoms have been assessed include: CT scan, MRI scan, echocardiography, and ultrasound. Optional tests may include electrocardiogram (EKG), electroencephalogram (EEG), and evoked potential tests. Generally, patients are evaluated on whether they have mild, moderate, or severe symptoms of HIE and the condition is controlled from there.
What Are the Effects of HIE?
The conditions of HIE vary, depending on whether the infant has mild, moderate, or severe symptoms. There are several different kinds of treatment, some that merely address emergency symptoms and keep your child alive, but there are others that try to reverse or diminish the brain damage.
Most of the time, babies with mild symptoms can have a life uninhibited by HIE, whereas babies with severe symptoms may have a shortened lifespan with a number of painful problems.
Effects of HIE may include developmental delays, epilepsy, cognitive issues, motor skill development delays, and neurodevelopment delays. The true severity of HIE generally cannot be determined until the baby reaches three to four years of age.
What Causes HIE?
There are a number of different causes of HIE, any of which can occur before, during, or after the baby is born.
Various problems or medical complications may cause HIE during pregnancy in the antepartum period. These include:
- Maternal diabetes with vascular disease
- Problems with blood circulation to the placenta
- Cardiac disease
- Congenital infections of the fetus
- Drug and alcohol abuse
- Severe fetal anemia
- Lung malformations
HIE can also affect infants during labor and delivery, or what is called the intrapartum period. Common intrapartum complications may include:
- Excessive bleeding from the placenta
- Very low maternal blood pressure
- Umbilical cord accidents
- Prolonged late stages of labor
- Abnormal fetal position
- Rupture of the placenta or the uterus
In addition, Infants can suffer from the effects of HIE in the postpartum period. Premature babies are particularly at risk of suffering brain injury or even death if HIE occurs after delivery. The most common causes of postpartum HIE include:
- Severe cardiac or pulmonary disease
- Infections, including sepsis and meningitis
- Severe prematurity
- Low neonatal blood pressure
- Brain or skull trauma
- Congenital brain malformations
In some cases, there are no identifiable causes for infant HIE.
How is HIE Treated?
Doctors have various options to treat HIE, all of which are determined by the causes of the condition and the amount of damage to the baby’s brain. This makes it impossible for physicians to develop a definitive treatment for neonatal cases of HIE. The basic goal of HIE treatment is to support the baby’s affected organs. Treatment options include:
- Mechanical ventilation to help a baby who can’t breathe without assistance
- Cooling the baby’s brain or body to reverse brain hypoxia caused by high temperatures
- Hyperbaric oxygen treatment in cases where HIE is caused by carbon monoxide intoxication
- General anesthesia and medications to control seizures
- Treatments to assist the baby’s heart function and control blood pressure