Cerebral blood flow, or CBF, is the blood supply to the brain in a given time. In an adult, CBF is typically 750 milliliters per minute or 15% of the cardiac output. This equates to an average perfusion of 50 to 54 milliliters of blood per 100 grams of brain tissue per minute. CBF is tightly regulated to meet the brain’s metabolic demands. Too much blood (a condition known as hyperemia) can raise intracranial pressure (ICP), which can compress and damage delicate brain tissue. Too little blood flow (ischemia) results if blood flow to the brain is below 18 to 20 ml per 100 g per minute, and tissue death occurs if flow dips below 8 to 10 ml per 100 g per minute.