Hypoxic Ischemic Brain Injury

The brain needs an adequate supply of blood and oxygen to the brain. The circulatory system pumps a continuous flow of oxygenated blood throughout the body, including to the brain. When the blood supply or oxygen levels are decreased, it can have an immediate impact on brain function.

Hypoxia involves reduced blood oxygenation. Ischemia is diminished blood flow to the brain. Together, ischemia with hypoxia can cause brain damage. The more severe the ischemic injury and the longer the brain goes without oxygen, the more extensive the damage can be. The key to treatment and recovery from hypoxic ischemia is rapid identification and intervention. Immediate action can reduce the damage from ischemia.

Failure to properly monitor a patient at risk of hypoxic ischemia or failure to timely diagnose a brain injury can result in serious injury or death. Patients of negligent doctors who suffer an injury due to hypoxic ischemia may have a claim for medical malpractice. If a loved one passes away due to lack of oxygen to the brain, the family members may have a medical malpractice wrongful death claim.

Hypoxic Ischemia in the Brain

There are a number of causes of hypoxic ischemia but the underlying physiologic process involves a reduction of blood flow to the brain and reduced blood oxygenation. When blood does not have enough oxygen, cardiac hypoxia can occur, which can reduce the amount of blood output from the heart, resulting in a reduction of blood flow to the brain.

The cause of hypoxic ischemia may depend on the age of the person involved. Infancy and children are more likely to suffer suffocation or cut off oxygen supply, leading to hypoxemia and brain hypoxia. For adults, ischemia is more often caused by a heart attack, with secondary hypoxia following the ischemic event.

Upon the onset of ischemia to the brain, the injury to the brain tissue is not applied equally. There is a series of biochemical events activated in the brain known as the ischemic cascade. Generally linear, although not always, a series of chemical activations damage neurons, triggering events like cell damage and cell death, inflammatory response, cerebral edema, and eventually brain damage and death.

Anoxic Brain Injury

Anoxic brain injury and hypoxic brain injury are related but different. Anoxic brain injury is damage caused by a total lack of oxygen. Hypoxic brain injury is an injury caused by a partial lack of oxygen. Hypoxic ischemia is a partial lack of oxygen to the brain combined with a decrease in blood flow to the brain.

Anoxia is often involved in birth injuries, where the child has their oxygen supply cut off for a period of time. Lack of oxygen at birth can lead to developmental delays, brain damage, and death.

Causes of Hypoxic Brain Injuries

There may be a number of causes of hypoxic brain injury. In adults, the most common causes of hypoxic-ischemia include cardiac arrest, vascular catastrophe like an aortic aneurysm, carbon monoxide poisoning, drug overdose, or head trauma.

Hypoxic ischemic brain injury after cardiac arrest is one of the most common causes of mortality and disability in survivors. Following a heart attack, blood flow to the brain is impaired. Even after a cardiac arrest is treated and the patient survives, the patient may not survive for very long or will be left with permanent neurologic damage.

Treatment and management of hypoxic ischemic brain injury generally involves limiting secondary injury, slowing and reversing the cascade that leads to further injury and cell death.

Identifying Hypoxic Ischemia and Treatment

One of the ways that doctors can diagnose hypoxic ischemic injury is through imaging. There may be a number of imaging options and multiple images may be taken to evaluate the patient, including:

Magnetic resonance imaging (MRI
Ultrasonography (US)
Computed tomography (CT)

Imaging allows professionals to get a look at what is going on inside the skull and brain from the outside. There are a number of factors that can affect how hypoxic ischemia manifests, including:

Brain maturity,
Duration of the ischemic event
Severity of the ischemia
Type of imaging
Timing of the imaging

In adults and older children, hypoxic ischemia may affect the deep gray matter nuclei, cortices, hippocampi, and cerebellum.

Hypoxic Ischemia Birth Injuries

Hypoxia to the fetus or child during birth may have a number of causes, including:

Surgical error
Birth complication
Anesthesia complication
Failure to monitor the mother or baby

As with adults with hypoxic ischemia, when a newborn is deprived of an adequate supply of oxygen and blood, the circulatory system cannot fully function, decreasing blood flow and further oxygen supply to the brain. If the hypoxic ischemia goes on for too long, brain damage can be damaged leading to swelling in the skull, or encephalopathy.

Risk factors that could suggest watching out for signs of hypoxia or anoxia during pregnancy and labor may include:

Preeclampsia (high blood pressure)
Prolonged labor
A baby in breech position
Problems with the umbilical cord, including a wrapped umbilical cord, and pressure on the cord, and prolapsed cord
Fetal distress, or an unusually slow or fast heart rate of the baby
Shoulder dystocia
Low blood pressure
Infection
Heart disease in the mother or baby
Placental abruption
Certain medications

An infant who suffers hypoxic ischemic encephalopathy (HIE) can suffer serious impairments, including:

Epilepsy
Developmental delays
Cognitive impairment
Neurodevelopmental delay
Motor Function impairment

Some signs of injury may appear immediately after birth, including organ damage or dysfunction and seizures. However, for other developmental, motor, and cognitive delays, the extent of the impairment may not be known until a few years after the child is born.

Diagnosing hypoxic ischemic encephalopathy often involves imaging, including MRI, echocardiography, ultrasound, CT, and electroencephalography. Other lab tests can show abnormal blood tests which could indicate an ischemic event.