The National Center for Biotechnology Information defines anoxic encephalopathy, or hypoxic-ischemic brain injury, as a "process that begins with the cessation of cerebral blood flow to brain tissue, which most commonly results from poisoning (for example carbon monoxide or drug overdose), vascular injury or insult, or cardiac arrest."
The "anoxic" description indicates that Rain's brain did not get any oxygen for a period of time. The less lethal hypoxic brain injury occurs when the brain gets some oxygen but not enough. The extent of brain damage for both hypoxic and anoxic brain injuries depends on the amount of time, even minutes or seconds, that the brain lacks necessary oxygen levels.
Anoxic encephalopathy, or hypoxic-ischemic brain injury, is a result of decreased oxygen delivery to the brain. It commonly results from poisoning (including drug overdose). Many patients who suffer anoxic brain injury expire without regaining full consciousness. 041b061a72