Statistical Signal Properties of the Pressure-Reactivity Index (PRx)
- Resource Type
- Authors
- Ari Ercole; Steven M. Bishop; Sophie Kelly
- Source
- Acta Neurochirurgica Supplement ISBN: 9783319657974
- Subject
- medicine.medical_specialty
Mean arterial pressure
Correlation coefficient
business.industry
Traumatic brain injury
Fisher transformation
Statistical properties
PRx
medicine.disease
Signal
Cerebral autoregulation
03 medical and health sciences
0302 clinical medicine
Bias
Fisher transform
Internal medicine
Cardiology
Medicine
030212 general & internal medicine
Cerebral perfusion pressure
business
030217 neurology & neurosurgery
Intracranial pressure
- Language
Objectives: The pressure-reactivity index (PRx) is defined in terms of the moving correlation coefficient between intracranial pressure (ICP) and mean arterial pressure (MAP) and is a measure of cerebral autoregulation ability. Histograms of PRx against cerebral perfusion pressure (CPP) show U-shaped behaviour- the minimum reflecting optimal cerebral autoregulation (CPPopt). However U-shaped behavior may also occur by chance. To date there has been no evaluation of the statistical properties of these signals. Materials and Methods: We simulated PRx/CPP distributions using synthetic ICP and MAP signals from Gaussian noise with known cross-correlation. We calculated the statistical distribution of extrema in the PRx/CPP relationship. Results: The calculation of PRx on random data is statistically biased to show a U-shaped behavior when the signals are positively cross-correlated (equivalent to PRx>0). For PR