What is cerebral autoregulation?
Cerebrovascular resistance (CVR), which is determined by the diameter of small arteries and arterioles, modulates CBF.[CBF=CPP/CVR][CBF=CPP/CVR]
A constant CBF over a wide range of systemic blood pressures, MAP 60 mm Hg–160 mm Hg, maintains CPP due to CVR. Outside this range of autoregulation, CBF varies directly with CPP.
Below the lower limit of CPP, CBF decreases as vasodilation becomes insufficient to promote CBF, resulting in ischemia.
Above the upper limit of CPP, increased intraluminal pressure results in a forceful dilation of arterioles (“luxury” perfusion), leading to disruption of the blood–brain barrier and brain edema.
The upper and lower limits of cerebrovascular autoregulation vary from one person to another, so the targeted CPP must be individualized.
