Effects of nitrous oxide on the human body
The painkilling and numbing qualities of nitrous oxide that is inhaled begin to take effect when the gas is at concentrations of 10 percent. At higher concentrations, approaching 100 percent, a sense of well-being, or "high," is experienced. A person experiencing a nitrous oxide high may:
Have slurred speech
Have difficulty in maintaining his or her balance or walking
Be slow to respond to questions
Be immune to any stimulus such as pain, loud noises, and speech
Lapse into unconsciousness
A person who is rendered unconscious by nitrous oxide is likely to stop breathing within a few seconds as a result of a depressed central nervous system--brain, brain stem, and spinal cord. Depression is caused by a combination of the effects of nitrous oxide and the lowered oxygen content that occurs as pure N2O displaces oxygen from the lungs with each succeeding inhalation of the gas; i.e., the person is asphyxiated.
If a person remains conscious and stops breathing the nitrous oxide, recovery (full consciousness and alertness) can occur within minutes. A person who loses consciousness, however, and continues to inhale a pure gas (providing a supply is still available) is most likely to die.
Death usually occurs when abusers, in their attempt to achieve a higher state of euphoria, breathe pure N2O in a confined space -- in a small room, inside an automobile or other vehicle cab, or by placing their head inside a plastic bag.
Tragedy can occur very quickly. Long-term exposure (several minutes) is not necessary before death occurs. Sudden, prolonged exposure to high levels of N2O, or a series of inhalations (without breathing clean air between inhalations) can result in death. The length of this action can be measured in seconds. Since the narcotic effect of nitrous oxide is very brief (several seconds) abusers tend to follow this repetitive action pattern.
Source:
http://www.cganet.com/N2O/factsht.asp
So if you want to play Russian Roullete go right ahead and do this. For anyone else who isn't suicidal I recommend meditation to reach the Astral.
To the poster: Stop immidiatly! Secondly tips like these are pretty stupid to give. Its like telling people to go climb an electric poles. Common man use your brain before posting stuff and before doing things to yourself.