Hypoxic-ischemic encephalopathy (HIE), sometimes called asphyxia, refers to a lack of oxygen or blood flow to a baby during pregnancy, labor and delivery. This lack of oxygen is responsible for a number of birth injuries, including cerebral palsy and other types of brain damage. It is also responsible for damage to other vital organs such as the heart, lungs and liver. The injuries caused by HIE are usually permanent.
Consequences of HIE
In addition to cerebral palsy, conditions caused by HIE include:
- Brain injury
- Seizure disorder
- Developmental delays, including delays in developing motor skills
- Cognitive deficits
HIE can also result in damage to other organs, such as the heart, lung and liver. Between 25 and 50 percent of infants with severe HIE die. Among those that survive, 80 percent will experience complications, including those listed above.
Causes of HIE
Although the causes of some HIE cases are unknown, the condition can result from mistakes during pregnancy, labor and delivery. All of the situations listed here can result in lack of oxygen to the brain:
- Excessive placental bleeding
- Very low maternal blood pressure
- Umbilical cord accidents
- Prolonged labor
- Abnormal position in utero
- Rupture of the placenta or the uterus
Prevention of HIE
Although nothing is ever certain, parents and medical staff can take steps to reduce the risk of birth injuries that cause HIE. Here are some tips:
- Be aware of the possibility of HIE and the risk
- Make sure your care provider knows what to do in the event of fetal distress
- Understand electronic fetal monitoring
- Ensure that your birth attendants, whether doctors, nurse-practitioners or midwives, are qualified to monitor your labor and delivery
- Make sure that an obstetrician and anaesthesiologist are available or on-call in the hospital
- Understand your legal rights, including the right to a second opinion
Treatment of HIE
There are steps health care providers can take when a baby is born with HIE. However, they must act fast to prevent further damage. Even after oxygen is restored to the baby, brain damage may continue. The goals of treatment when HIE is suspected in a newborn infant are to:
- Maintain blood glucose at normal levels
- Maintain blood pressure at normal levels
- Prevent or control seizures
- Prevent or minimize cerebral edema, or swelling
Babies with severe HIE usually need a ventilator to maintain blood gases at proper levels. One method of treating HIE in newborns is to keep the baby’s temperature very low. Known as cooling therapy, the baby’s temperature is carefully lowered for 72 hours after birth. This slows down the child’s metabolism and may interrupt or slow the damaging effects of HIE. However, it is important that cooling therapy be started right after birth to achieve maximum effect.
Although not all babies respond to cooling therapy, studies have shown that babies born at 36 weeks or later have an improved chance of survival than babies who did not receive this type of therapy. Also, babies examined at two years of age who received cooling therapy have less brain damage and disability.
While HIE may not be preventable in all cases, a care team’s response to HIE can make a big difference. Expectant parents may want to ask their doctors how they would respond to HIE if their babies are in distress because of oxygen deprivation.