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The use of carefully controlled but exaggerated ventilation to lower carbon dioxide (CO2) levels in the blood and reduce cerebral blood flow. It is used to treat cerebral edema (e.g., after head injury), but its use remains controversial despite decades of research. Typically, the partial pressure of CO2 is lowered to about 28 to 32 mm Hg. Lower levels of CO2 produce reductions in cerebral blood flow that may damage the brain.
CAUTION!Having the patient breathe in and out of a paper bag is to be discouraged because it leads to hypoxia.
See also: hyperventilation