What Is Perinatal HIE?
Perinatal hypoxic-ischemic encephalopathy (HIE) is a serious and life-threatening infant brain damage that can occur during childbirth. Hypoxia means any interruption of oxygen circulation; ischemia means blood flow restriction. Perinatal HIE happens when blood supply and oxygen to a baby's brain are blocked or interrupted during childbirth, leading to brain cell death. The oxygen and blood supply to the brain can be interrupted before or during birth or even shortly after birth. Perinatal HIE is also called perinatal asphyxia, asphyxia, or birth asphyxia.
Perinatal HIE not only affects the brain, but the effects of low blood flow or oxygen can also cause problems in the liver, heart, lungs, bowel, and kidneys. The symptoms of HIE are graded as mild, moderate, or severe. When HIE is graded from moderate or severe, it can lead to long-term disability and sadly result in death. However, perinatal HIE is a rare condition that occurs in about three out of every 1000 births.
The extent of damage from HIE cannot be calculated immediately after birth because brain damage occurring due to HIE is an evolving process. The interruption in blood flow to the brain causes brain cell death and releases toxic substances to other cells, leading to the death of those cells, and the chain reaction continues. So, the brain injury may take hours or days to spread. Therapeutic hypothermia (treatment used for people with cardiac arrest) can help disrupt this chain reaction. HIE damage may not be apparent in some cases until the child presents with developmental delays like difficulty meeting milestones such as walking or crawling.
What Are the Causes of Perinatal HIE?
The exact cause of HIE cannot be identified all the time. Health problems, complications around the time of birth, or negligent actions such as the following can cause it:
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Mismanagement or Negligence in High-Risk Pregnancy - High-risk pregnancy cases like preeclampsia and gestational diabetes require more careful monitoring and treatment.
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Umbilical Cord Complications - The umbilical cord supplies oxygen and nutrients to the fetus and removes fetal waste. Any compression, obstruction, or functional deformities can increase the risk of perinatal HIE.
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Placental or Uterine Complications - As the umbilical cord, the placenta, and the uterus play a vital role in providing oxygenated blood to the fetus. Placental and uterine abnormalities like placental abruption (separation of the placenta from the uterus before the birth), placenta previa (attachment of placenta too close to the cervix can cause oxygen deprivation and severe bleeding during delivery), placental insufficiency (inefficiency of the placenta to deliver required blood to the fetus), and uterine rupture (partial or complete rupture of the uterus tears).
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Infections - Infections can easily spread from the mother to the baby during delivery. Especially if the medical team does not take adequate precautions to check or treat an infection.
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Improper Monitoring of Fetal Heartbeat - If there are signs of fetal distress during delivery, vitals should be motioned, and their oxygen supply should be restored. If necessary, an emergency C-section should be conducted. If fetal heart rate monitoring does not occur or is irregular, the signs of danger may be missed, leading to serious complications.
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Premature Birth - Premature babies are at increased risk for prenatal HIE because their lungs are underdeveloped.
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Prolonged Labor - Prolonged labor can deprive the fetus of oxygen supply as uterine contractions compress the placenta and umbilical cord, their source of oxygen, leading to severe complications.
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Medication Problems - Medications such as Pitocin and Cytotec, prescribed to induce or enhance labor, can sometimes cause strong and frequent uterine contractions, cutting off the oxygen supply to the baby.
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Neonatal Condition - Complications during the neonatal period, especially during the baby's first month of life, can cause problems such as jaundice, neonatal hypoglycemia, and respiratory distress, contributing to an HIE diagnosis.
What Are the Signs and Symptoms of Perinatal HIE?
Based on the severity of perinatal HIE, the symptoms are classified as the following:
In Mild Perinatal HIE:
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Deep tendon reflexes are abnormal and brisk. The muscle tone is stiff during the first few days.
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Temporary behavioral abnormalities include extreme irritability, feeding difficulties, and excessive crying or sleeping.
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The symptoms often resolve in 24 hours.
In Moderate Perinatal HIE:
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Infants are lethargic, with decreased muscle tone and an absence of reflexes.
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Grasping, sucking, and Moro reflexes may be poor or absent.
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Occasional periods of apnea (serious sleep disorder causing repeated stops and starts of breathing).
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Seizures within the first 24 hours after birth.
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Recovery within 1 to 2 weeks.
In Severe Perinatal HIE:
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Extremely generalized seizures increase in frequency 24 to 48 hours after onset.
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As the injury progresses, seizures will reduce, and the EEG (electroencephalogram) will become unresponsive to an external stimulus or show a suppression pattern.
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Irregular breathing.
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Extreme hypotonia.
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Infants may not respond to any physical stimulus (coma).
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Irregular breathing pattern requiring ventilatory support.
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Abnormal eye control.
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Abnormal blood pressure and heart rate.
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Cardiorespiratory failure.
How Is Perinatal HIE Diagnosed?
Perinatal HIE can be diagnosed by signs like neonatal neurologic sequelae (hypotonia, seizures, coma). Additional tests done for diagnosis are:
Imaging Studies:
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Magnetic resonance imaging (MRI) of the brain.
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Echocardiography (echo).
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Cranial ultrasonography.
Laboratory Studies:
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Serum electrolyte levels.
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Renal function studies.
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Cardiac and liver enzymes.
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Coagulation tests like fibrinogen levels, prothrombin time, and partial thromboplastin time.
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Arterial blood gas - (used to assess the acid-base status and to avoid hyperoxia, hypoxia, hypercapnia, and hypocapnia.
Additional Studies:
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Electroencephalography (EEG).
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A hearing test (increased incidence of deafness is noted in infants with hypoxic-ischemic encephalopathy).
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Ophthalmic examination.
What Is the Treatment for Perinatal HIE?
The treatment for perinatal HIE is called therapeutic hypothermia. In this technique, the infant's brain or body is cooled below normal temperatures to slow the cellular damage occurring within the brain. This allows the infant's brain to recover and minimize the long-term impact of HIE. The treatment must be provided within six hours of birth. However, some studies suggest that it may be beneficial for 24 hours.
Along with therapeutic hypothermia, healthcare professionals should provide supportive care, such as stabilizing breathing, controlling and preventing seizures, minimizing brain swelling, etc. Unfortunately, brain damage from hypoxia is permanent and cannot be fixed with medications or surgery. So for long-term benefits, babies require various life-long treatments and therapies to minimize symptoms and maximize function.
Conclusion
Perinatal HIE is a serious condition affecting newborns due to interruption or restriction of blood and oxygen supply to the brain leading to brain cell damage. Based on the extent of brain damage, the severity of the symptoms varies. Immediate treatment is required to nullify the cascade of brain cell damage. Because the damage is permanent, the baby will have to face lifetime abnormalities, and the treatment should also be continued for the long term.
