Cerebral Ischemia occur when cerebral blood flow is less than
the threshold of cerebral blood flow ( CBF) below which neuronal function is impaired and the tissue is at risk of infarction is around 22 ml/100 g/ min Hyperventilation causes decreased PaCO2 which subsequently leads to aerial vasoconstriction thus lowering cerebral blood flow (CBF), cerebral blood volume, and ICP. This effect is mediated my pH changes in the extracellular fluid which cause cerebral vasoconstriction or vasodilation depending on the pH. Ref Harrison20th edition pg 2567
10 ml/ 1OOg/minute
20 ml/ 1OOg/minute
40 ml/ 1OOg/minute
50 ml/1OOg/minute
C.N.S