Anoxic Hypoxia
Anoxic refers to a total lack of oxygen; hypoxic means a partial lack of oxygen. Overall, the more complete the lack of oxygen, the more severe the harm to the brain and the greater the consequences.
The brain cannot survive more than 2 minutes without oxygen. These types of injury to the brain usually occur after a near drowning, suffocation, smoke inhalation or a crush injury to the chest. In older individuals, hypoxia or anoxia occurs with a stroke, a heart attack or a pulmonary arrest. Hypoxic or anoxic brain injuries frequently have an initial incident of widespread brain swelling (edema). The length and the extent of oxygen deprivation determines the subsequent extent of injury to the brain, but the exact duration and extent are often unknown so the degree of injury may not be recognized until days, weeks or months following the event.