Brain Tissue Oxygenation

The brain represents 2% of body weight, but consumes 20% of the body’s oxygen supply as a result of its high metabolic demand. This chapter reviews the physiological determinants of cerebral oxygenation, and the role that ischaemia and hypoxia play in the two pathologies most commonly encountered in the neurocritical care unit - traumatic brain injury (TBI) and sub-arachnoid haemorrhage (SAH). It focuses primarily on the emerging technique of brain tissue oxygen monitoring (PbtO2) which is increasingly used to guide treatment in neurocritical care settings. Despite enormous potential, this method faces significant challenges associated with the complex interplay of systemic and local factors affecting cerebral perfusion and oxygenation. The chapter documents the evolution of PbtO2 monitoring and the evidence for its use. It illustrates how this technique has the potential to enhance clinical management strategies and significantly improve patient outcomes from acute brain injury.