For newborn infants starved of oxygen during birth there is now evidence that hypothermia therapy for neonatal encephalopathy applied within 6 hours of<unk>  effectively improves survival and neurological outcome. In adults, however, the evidence is less convincing and the first goal of treatment is to restore oxygen to the brain. The method of restoration depends on the cause of the hypoxia. For mild-to-moderate cases of hypoxia, removal of the cause of hypoxia may be sufficient. Inhaled oxygen may also be provided. In severe cases treatment may also involve life support and damage control measures. A deep coma will interfere with the body's breathing reflexes even after the initial cause of hypoxia has been dealt with; mechanical ventilation may be required. Additionally, severe<unk>  causes an elevated heart rate, and in extreme cases the heart may tire and stop pumping. CPR, defibrilation, epinephrine, and atropine may all be tried in an effort to get the heart to resume pumping. Severe<unk>  can also cause seizures, which put the patient at risk of self-injury, and various anti-convulsant drugs may need to be administered before treatment. There has long been a debate over whether newborn infants with<unk>  should be resuscitated with 100% oxygen or normal air. It has been demonstrated that high concentrations of oxygen lead to generation of oxygen free radicals, which have a role in reperfusion injury after asphyxia. Research by Ola Didrik Saugstad and others led to new international guidelines on newborn resuscitation in 2010, recommending the use of normal air instead of 100% oxygen. Brain damage can occur both during and after oxygen deprivation. During oxygen deprivation, cells die due to an increasing acidity in the brain tissue (acidosis). Additionally, during the period of oxygen deprivation, materials that can easily create free radicals build up. When oxygen enters the tissue these materials interact with oxygen to create high levels of oxidants. Oxidants interfere with the normal brain chemistry and cause further damage (this is known as "reperfusion injury"). Techniques for preventing damage to brain cells are an area of ongoing research. Hypothermia therapy for neonatal encephalopathy is the only evidence-supported therapy, but antioxidant drugs, control of blood glucose levels, and hemodilution (thinning of the blood) coupled with drug-induced hypertension are some treatment techniques currently under investigation. Hyperbaric oxygen therapy is being evaluated with the reduction in total and myocardial creatine phosphokinase levels showing a possible reduction in the overall systemic inflammatory process. In severe cases it is extremely important to act quickly. Brain cells are very sensitive to reduced oxygen levels. Once deprived of oxygen they will begin to die off within five minutes.
Cerebral hypoxia
Silent hypoxia
Histotoxic hypoxia
Pseudohypoxia
Hypoxia 
Anoxia
Oxygen toxicity
Nitrogen narcosis