A lowered body temperature reduces the body’s need to perform many of the functions that utilize energy. The body can thus concentrate on the damaged cells that require repair.

Two Phases of Damage

There are two phases during which the brain suffers damage due to lack of oxygen. When the brain is deprived of oxygen it begins to suffer the consequences immediately. During this immediate phase brain cells that are starved of oxygen begin to create a substance that can cause further damage. The longer the brain cells are without oxygen the more extensive the damage will likely be. Once oxygen is restored to the brain it begins to function again. However, the concern is not yet over.

Delayed apoptotic cell death occurs as part of the secondary phase which may be between 6 to 72 hours after the original injury. The enzymes that were released during the period of oxygen deprivation, called caspases, will cause damage to brain cells. It is during this time that the onset of seizures is most likely to begin, although they can start at any time. Anti-seizure medications may be provided along with cooling therapy. The application of cooling therapy may diminish seizures or reduce their severity. Cooling could also reduce further brain cell damage.

How Neonatal Cooling Works

Through observation over time physicians noticed that injured people who were colder seemed to have more positive outcomes than those who were at normal temperatures. Therapeutic hypothermia began to be used on patients who were at high risk of brain damage because of heart attacks, strokes, or spinal cord injuries. Lowering the body’s core temperature slows down the body’s biological processes and might lengthen the window of time during which treatments may be most effective. It is not known exactly how the mechanics of lowered body temperature works, however, it is found to be effective in some cases.

Prognosis for Infants with HIE

The prognosis for infants with HIE varies from child to child. Doctors will perform tests to help determine the severity of a brain injury. Those with mild injuries may recover fully with few if any neurological problems or could have some developmental delays. Others may have moderate damage and could suffer from physical or developmental disabilities or cerebral palsy. Still, others could have severe damage and are at high risk for cerebral palsy. It is estimated that as many as 85% of infants diagnosed with severe HIE may die. Those who receive cooling treatment may suffer less serious brain damage than they would have without treatment. They may have higher function which will become more evident when they begin walking and talking. Ongoing care and treatment will be done to continue to measure a child’s brain activity and neurological abilities.