Why and how to assess cerebral autoregulation?

Around the turn of the century, a better understanding of the complex physiology of cerebral blood flow (CBF) regulation has emerged. It is now acknowledged that cerebral autoregulation is much more complicated than we previously thought it was, with the shape of the autoregulation curve and limits of autoregulation that may vary enormously and unpredictably, both within and between patients. The consequence is that to safeguard the cerebral circulation, the dogma that an empirically chosen blood pressure guarantees adequate CBF in any individual patient has to be abandoned. Integration of cerebral autoregulation monitoring in daily perioperative patient care offers the opportunity to guide blood pressure management to the individual patient's need. The most common approach tests the effect of changes in blood pressure on an estimate of CBF. However, a "gold standard" to assess cerebral autoregulation is not yet available, and the literature shows considerable disparity of methods and criteria.