Abstract
Autoregulation of cerebral blood flow is a vital function that guarantees that cerebral blood flow is being maintained over a wide range of blood pressure values. The matching between cerebral blood flow and the cerebral metabolic requirements involves vasodilation/constriction of the cerebral arterioles in response to decrease/increase of the cerebral perfusion pressure, respectively. The lower limit of cerebral autoregulation is defined as the mean arterial pressure below which cerebral blood flow becomes pressure passive. Keeping blood pressure within the cerebral autoregulatory range for patients undergoing cardiac surgery has been shown to improve postoperative outcomes. The objective of this article is to summarize the results of recent studies that may enable us to estimate the lower limit of cerebral autoregulation to reduce the risk of cerebral hypoperfusion.