K. P. Budohoski , C. Zweifel , M. Kasprowicz , E. Sorrentino, J. Diedler , K. M. Brady , P. Smielewski ,D. K. Menon, J. D. Pickard, P. J. Kirkpatrick  and M. Czosnyka

 Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Addenbrooke’s Hospital, Hills Road,Cambridge CB2 0QQ, UK
 Department of Neurosurgery, University Hospital Basel, Basel, Switzerland
 Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, Wroclaw, Poland
 Department of Neurology, University of Heidelberg, Heidelberg, Germany
 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
 Division of Anaesthesia, University of Cambridge, Addenbrooke’s Hospital, Cambridge, UK
 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK

Editor’s key points
1\Brain tissue oxygenation (Pbto2) and near-infrared spectroscopy (NIRS) parameters respond to changes in arterial pressure (AP) and intracranial pressure (ICP).
2\NIRS and transcranial Doppler (TCD) signals react first to AP and ICP changes. The reaction of PbtO2 is delayed, revealing that the analysed modalities monitor different stages of cerebral oxygenation.
3\In 77% of events tissue oxygenation index (TOI) and PbtO2 reacted in the same direction.