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Time for a #factcheck on cerebral autoregulation.
1/10
"Cerebral autoregulation is the mechanism that keeps cerebral blood flow (CBF) stable across a wide range of perfusion pressure".
WRONG. But widespread... This is only true for very slow changes in blood pressure (BP).
1/10
"Cerebral autoregulation is the mechanism that keeps cerebral blood flow (CBF) stable across a wide range of perfusion pressure".
WRONG. But widespread... This is only true for very slow changes in blood pressure (BP).
2/10 For faster changes in BP, CBF changes almost as much as BP. E.g. the 10-20% drop in BP when we stand up leads to a 10-20% drop in CBF. Autoregulation can not prevent this drop, it only makes sure CBF recovers before BP does.
3/10 Slow BP changes: examples are treatment of hypertension, or gradual decline in BP during sepsis. Indeed, here CBF is maintained more or less stable. Fast changes: seconds to minutes: standing up, or an acute dose of nitroglycerine, or a Valsalva. CBF is NOT held stable here.
