Incidence and mechanisms of cerebral ischemia in early clinical head injury.

Antemortem demonstration of ischemia has proved elusive in head injury because regional CBF reductions may represent hypoperfusion appropriately coupled to hypometabolism. Fifteen patients underwent positron emission tomography within 24 hours of head injury to map cerebral blood flow (CBF), cerebral oxygen metabolism (CMRO2), and oxygen extraction fraction (OEF). We estimated the volume of ischemic brain (IBV) and used the standard deviation of the OEF distribution to estimate the efficiency of coupling between CBF and CMRO2.

Effect of hyperventilation on cerebral blood flow in traumatic head injury: clinical relevance and monitoring correlates.

Objective: To investigate the effect of hyperventilation on cerebral blood flow in traumatic brain injury.

Design: A prospective interventional study.

Setting: A specialist neurocritical care unit.