The prognostic role of PRx is confirmed but with a lower threshold of 0.05 for favorable outcome than for survival (0.25). Results for ICP are in line with current guidelines. However, the lower value in elderly and in females suggests increased vulnerability to intracranial hypertension in these groups.

Background and Purpose-Delayed cerebral ischemia (DCI) is a recognized contributor to unfavorable outcome after subarachnoid hemorrhage (SAH). Recent data challenge the concept of vasospasm as the sole cause of ischemia and suggest a multifactorial process with dysfunctional cerebral autoregulation as a component. We tested the hypothesis that early autoregulatory failure, detected using near-infrared spectroscopy-based index, TOxa and transcranial Dopplerbased index, Sxa, can predict DCI. Methods-In this prospective observational study we enrolled consecutive patients with aneurysmal SAH that occurred <5 days from admission.

TCD pulsatility index can be easily and quickly assessed but is usually misinterpreted as a descriptor of CVR. The mathematical model presents a complex relationship between PI and multiple haemodynamic variables.