This international, multicentre prospective cohort study will assess whether perioperative duration and magnitude of mean arterial pressure (MAP) outside of an individual's cerebral autoregulation (CA) limits using near-infrared spectroscopy (NIRS) and transcranial Doppler (TCD) are associated with adverse neurological events. It is to investigate whether patients with a higher burden of cerebral haemodynamic insults have an increased incidence or poorer neurological outcomes. Associations between neurologic outcomes, neurobiomarkers and genetic tests will be explored.