Hypoxic ischemic encephalopathy (HIE) is a condition in which the entire brain does not receive enough oxygen, but isn’t completely deprived. This particular condition refers to an oxygen deficiency to the brain as a whole, rather than a part of the brain. Although the term most often refers to injury sustained by new born infants, HIE can be used to described any injury from low oxygen.

HIE can be fatal. Within as little as five minutes of oxygen deprivation, brain cells can begin dying. The disease can also cause long-term damage, including mental retardation , delayed development, seizures , and cerebral palsy .

Blood Supply to the Brain  

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There are a variety of causes of HIE. Any injury and many health conditions can potentially cause oxygen deprivation to the brain. Some common causes are:

• Injury or complication during birth
• Respiratory failure
• Blocked or ruptured blood vessel
• Carbon monoxide or cyanide poisoning
• Drug overdose
• Drowning
• Lack of oxygen due to smoke inhalation
• Extremely low blood pressure
• Strangulation
• Cardiac arrest
• Carbon monoxide poisoning
• High altitudes
• Choking
• Compression or injury to the trachea that reduces or stops breathing
• Complications from general anesthesia
• Diseases that cause paralysis of the respiratory organs or muscles (eg, myasthenia gravis , Guillain-Barre syndrome )

Any injury, complication, or health condition that causes the brain to have a reduction in blood flow and oxygen deprivation is a risk factor for HIE.

Symptoms include:

• Mild case:
• Difficulty concentrating or paying attention
• Poor judgment
• Poor coordination
• Euphoria
• Extreme lethargy
• Severe oxygen deprivation:
• Seizures
• Coma
• No brain stem reflexes (eg, breathing, responding to light)
• Only blood pressure and heart function reflexes are functioning

The doctor must work quickly to perform a physical exam. Typically, the history is the most important factor in making the diagnosis.

Tests may include the following:

• CT scan —a scan that uses x-rays and computer software to make pictures of your brain
• MRI scan —a test that uses magnetic waves to make pictures of structures inside the brain
• Electrocardiogram (EKG, ECG) —a test that records the heart’s activity by measuring electrical currents through the heart muscle
• Echocardiogram —a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart
• Blood tests, including arterial blood gases and blood glucose levels
• Electroencephalogram (EEG) —a test that records the brain’s activity by measuring electrical currents through the brain
• Evoked potentials—a test that shows whether or not the brain has an electrical response to sensations like sight and touch

Treatment depends on the underlying cause of the condition, as well as the severity of the damage to the brain. Treatment options include:

• Life-sustaining treatment—If brain function has stopped but damage is not yet extensive, life-sustaining treatment is administered.
• Mechanical ventilation —Mechanical ventilation may be needed to sustain breathing.
• Treatments for the circulatory system—Treatments are administered to maintain heart function and control blood pressure.
• Seizure control— Medications and general anesthesia may be administered to control seizures.
• Cooling blankets—Hypoxic brain damage is often caused by heat, so cooling blankets or other means of cooling may be applied to reduce the body's temperature.
• Hyperbaric oxygen treatment —This treatment is especially used in cases of carbon monoxide poisoning.

In most cases, HIE is unexpected and cannot be prevented. To prevent significant or long-term brain damage once the oxygen supply has been reduced, CPR may be administered.