Table 3 Indices of static and dynamic CA used in the literature
Index | Definition | Static/dynamic | Impaired CA | BU |
|---|---|---|---|---|
THRT [55] | Changes in cerebral blood flow velocity after a brief compression of the ipsilateral common carotid artery. THRT = FVsystolic (hyperemia)/FVsystolic (baseline) | Static | ≤ 1.1 | Yes |
ARI [54] | Autoregulation index derived from cerebral blood flow velocity and transfer function analysis | Dynamic | ≤ 4 | Yes |
PRx [56] | Moving Pearson’s correlation coefficient between intracranial pressure and blood pressure. | Quasi- Static | ≥ 0.3 | No |
Mx/Mxa [57] | Moving Pearson’s correlation coefficient between cerebral blood flow velocity and blood pressure | Quasi- Static | ≥0.3 | Yes |
COx [58] | Correlation coefficient between MAP and rScO2 | Static | +1 | No |
RoR [59] | Ratio of slope of cerebral blood flow velocity recovery normalized by blood pressure after thigh cuff release | Dynamic | - | Yes |