Recent developments in neurocritical care monitoring are promising. New technology and application of state-of-the-art techniques promise to expand our understanding of the mechanisms of secondary injury and minimize the events that lead to poor outcome. The goal of neurocritical care is simple—to provide adequate nutrition and oxygen to injured brain tissue, and to prevent secondary insults to potentially viable brain. Cerebral blood flow is an indirect measurement of adequate tissue oxygenation and nutrition. Therfore a number of methods of assessing cerebral blood flow are available. These include transcranial Doppler ultrasonography, xenon CT, single-photon emission CT, and positron emission tomography. However, none of these techniques allows a reliable continuous bedside assessment of cerebral blood flow but provide snapshots of an immensely fluid process. Continuous bedside techniques include monitoring jugular venous oxygen saturation (SjvO2) and thermal diffusion local cerebral blood flow probes. Jugular venous oxygen monitoring provides an indirect measure of the balance between cerebral blood flow and metabolism and is sensitive at detecting episodes of global cerebral ischemia. Local cerebral blood flow probes based on thermal diffusion have been found to be quite sensitive in tracking cerebral blood flow, but are limited by artifacts and by the small region that they monitor. Near-infrared spectroscopy is a continuous bedside technique for monitoring changes in cerebral oxygenation. It is also sensitive in detecting extra-axial blood accumulation. Microdialysis can be performed in a continuous fashion at the bedside and may aid in guiding therapy in the future. Despite the promise of these new techniques, the cornerstone for assessment in neurocritical care units remains frequent neurological examination by the nursing and physician staff supplemented by ICP and periodic CT scan data.
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