The relationship between the intracranial pressure-volume index and cerebral autoregulation.

Objective The pressure–volume index (PVI) can be used to assess the cerebrospinal fluid dynamics and intracranial elastance in critically ill brain injured patients. The dependency of PVI on the state of cerebral autoregulation within the physiologic range of cerebral perfusion pressure (CPP) can be described by mathematical models that account for changes in cerebral blood volume during PVI testing. This relationship has never been verified clinically using direct PVI measurement and independent cerebral autoregulation assessment.