Lack of oxygen to the brain causes cerebral hypoxia. The National Institute of Neurological Disorders and Stroke, or NINDS, explains that in this condition there is decreased oxygen supply to the brain although the blood flow remains sufficient. Symptoms of mild cerebral hypoxia are memory loss, poor motor coordination, poor judgment and inattentiveness.
The NINDS further states that causes of cerebral hypoxia include choking, strangling, drowning, suffocation, head trauma, carbon monoxide poisoning, cardiac arrest and complications of general anesthesia. Because brain cells are very sensitive to oxygen deprivation, they start to die within five minutes after oxygen supply stops. Longer periods of hypoxia cause coma and seizures. Brain death also eventually occurs, which is a condition wherein the brain has no measurable activity even though cardiovascular function is preserved. At this point, life support is needed for breathing.
The Headway Brain Injury Association states that the body requires a constant oxygen supply to survive, and it uses 20 percent of the body’s oxygen intake. When the oxygen supply is cut off, the brain’s functioning is disturbed and irreversible damage occurs if it is not quickly restored. A person loses consciousness within 15 seconds, and brain damage begins after four minutes without oxygen supply.
Cerebral hypoxia requires emergency treatment and immediate oxygen supply to reduce the risk of severe brain damage or brain death, MedlinePlus states.