Until recently, doctors believed pumping pure oxygen to stroke patient is the fastest and most effective way to deliver oxygen to needy lung or brain tissue. But a new study suggest that pumping pure during a medical emergency may worsen rather than reduce potential brain damage. Medical personnel routinely smack an oxygen mask on people struggling to breathe, as well as to stroke victims left oxygen-deficient in some parts of their brains. Pure oxygen causes rapid breathing that is when it is pumped in more carbon dioxide is exhaled from the lung, and that makes the blood vessels much smaller, shrunken vessels cannot deliver as much blood, or the oxygen that's in the blood, to the brain or anywhere else in the body. According to a study it was found that beside constricting blood flow, administering pure oxygen caused some areas of the subjects brains to go haywire.

Researchers discovered that the negative effects can be avoided if the oxygen is mixed with as little as 5 percent carbon dioxide before being administered. The combo neither triggered significant changes in any of the aforementioned brain regions nor disturbed the hypothalamus.
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