Cerebral hypoxia is a lack of oxygen in the brain. Some causes of this condition include cardiac arrest, choking, suffocation, near drowning, and brain injury. The reduction of oxygen supply to the brain is considered an emergency situation and requires immediate life support treatment to restore functionality and prevent irreversible brain damage and death.
Definition & Facts
Cerebral hypoxia occurs when the oxygen supply to the brain is reduced. This condition can occur as a result of suffocation, cardiac arrest, brain injury, and other events during which the flow of oxygen to the brain is disrupted.
Cerebral hypoxia is a serious condition which hinders the ability of brain cells to function as it reduces their supply of oxygen and nutrients. Loss of functionality begins immediately and brain cells can begin to die from oxygen and nutrient deprivation within five minutes, potentially leading to severe and irreversible brain damage and death if not treated quickly.
Cases range from mild to severe, depending on the length of time the brain was lacking in oxygen, the amount of damage which resulted, and the area of the brain affected. Individuals who experience mild cases have the best chance of a full recovery with little damage. However, more severe cases can cause devastating brain damage and lead to a persistent vegetative state, brain death, or death. Types of cerebral hypoxia include the following:
- Diffuse cerebral hypoxia results in mild to moderate brain function impairment due to low oxygen levels in the blood. This is most common in individuals who have held their breath for a long time or in instances of choking.
- Focal cerebral ischemia is due to a lack of oxygen in a specific area of the brain usually due to stroke or a blockage in a blood vessel.
- Global cerebral ischemia is when blood flow to the brain ceases. This is a form of cerebral anoxia that arises due to severe strokes, traumatic brain injuries, and suffocation.
- Cerebral infarction occurs when blood flow ceases to multiple areas of the brain, often due to a stroke, leading to extensive brain damage.
Symptoms & Complaints
Severe symptoms as a result of prolonged oxygen deprivation include loss of consciousness, coma, seizure, inability to breathe, increased heart rate (tachycardia), absence of a response in the pupils of the eye to light, and brain death.
Medical treatment should be sought immediately in response to these symptoms to prevent further brain damage or death.
There are numerous potential causes of cerebral hypoxia. These include stroke, cardiac arrest, irregular heartbeat (cardiac arrhythmia), complications from anesthesia during surgery, choking, carbon monoxide poisoning, drowning, asphyxiation, smoke inhalation, travel at high altitudes above 8,000 feet (2,438 meters), brain injury, strangulation, electric shock, and drug overdose. Some medical conditions can also lead to a reduction of oxygen in the brain, including low blood pressure (hypotension) and severe asthma attacks.
Diagnosis & Tests
Cerebral hypoxia is generally diagnosed based on a physical examination and the patient’s medical history. Tests can include blood tests to determine the amount of oxygen in the blood, brain angiogram, computed tomography (CT) scans to provide three-dimensional images of the brain, magnetic resonance imaging (MRI) scans for detailed images of the brain, echocardiogram to look at the heart, electrocardiogram (ECG) to measure the heart’s electrical activity, and electroencephalogram (EEG) to measure electrical activity in the brain and identify seizures. Brain death is diagnosed when all functions of the brain have been lost.
Treatment & Therapy
Cerebral hypoxia is an emergency condition which requires immediate treatment, the extent of which depends on the cause and severity of the case. The risk of detrimental brain damage and death can be reduced if oxygen supply is quickly restored. In cases such as choking, the removal of the source of the oxygen deprivation is of primary importance.
Treatment for severe cases of cerebral hypoxia consists of basic life support functions including oxygen and breathing assistance (mechanical ventilation) as well as the administration of intravenous fluids, blood, and medications to support blood pressure, heart rate, and to suppress seizures.
The effectiveness of treatment depends on the extent of the brain injury, including the length of time the brain lacked oxygen. Recovery is unpredictable and although there are some factors which can provide an initial prediction of the patient's recovery, unknown variables and conditions make it difficult to determine with certainty the extent to which recovery will occur. Results also differ between individual cases. Full recovery is most common among patients who were only briefly unconscious.
The recovery process can be challenging. It is important to begin rehabilitation early in order to return as much functionality as possible. Full rehabilitation could take months or years. The chances of recovery are reduced and the risk of brain death or death increases the longer the patient is unconscious. More severe cases may result in only partial recovery and patients may continue to experience seizures and abnormal movements such as twitching and jerking.
Prevention & Prophylaxis
Participating in sports and activities where traumatic head injuries are common such as football and boxing, swimming or diving during which the breath is held for long periods of time, and high-altitude mountain climbing all put one at a greater risk. Proper safety precautions should be adopted when partaking in these activities.
If an individual is deprived of oxygen unexpectedly, such as during a fire or as a result of a near drowning or suffocation, performing CPR (cardiopulmonary resuscitation) as soon as possible can keep the condition from worsening.