Pressure Reactivity Index
Also written as: PRx — Pressure Reactivity Index
Correlation coefficient between intracranial pressure and mean arterial pressure used to assess cerebrovascular reactivity.
Full Definition
The Pressure Reactivity Index (PRx) is calculated as a moving correlation coefficient between slow changes in intracranial pressure and mean arterial pressure over 5-minute periods. Values near zero indicate intact cerebrovascular reactivity, while positive values suggest impaired autoregulation and passive pressure transmission. PRx values above +0.25 are associated with poor outcomes in traumatic brain injury patients. This index helps determine optimal cerebral perfusion pressure targets and guides blood pressure management in neurocritical care patients with impaired autoregulation.
Usage
Usage note: Always include the sign (+ or -) when reporting PRx values.
In Context
- "The pressure reactivity index remained elevated at +0.4, indicating severely impaired cerebrovascular autoregulation." — Neurocritical care consultation