Cerebral Autoregulation Index
Also written as: ARI — Cerebral Autoregulation Index
A quantitative measure of the brain's ability to maintain constant cerebral blood flow despite changes in blood pressure.
Full Definition
The Cerebral Autoregulation Index (ARI) is a numerical value that quantifies the effectiveness of cerebral autoregulation, typically ranging from 0 (absent autoregulation) to 9 (perfect autoregulation). It is calculated using transcranial Doppler measurements during rapid changes in arterial blood pressure. Values below 4 indicate impaired autoregulation and are associated with poor outcomes in neurocritical care patients. This index helps clinicians optimize blood pressure management in patients with brain injury.
Usage
Usage note: Always capitalize when used as an acronym; use lowercase when spelled out except for proper nouns.
In Context
- "The patient's Cerebral Autoregulation Index of 2 indicated severely impaired autoregulation following the traumatic brain injury." — Clinical assessment report