Monitoring of the central nervous system

Clinical studies have identified a close relationship between variables such as hypoxia, increased intracranial pressure, arterial hypotension, seizures, and neurologic outcome. This indicates the need for techniques to monitor the central nervous system, including the measurement of cerebral blood flow (CBF), cerebral oxygenation, and neuronal function. Changes in CBF induced by anesthetics or narcotics, or during dynamic CBF autoregulation can be measured continuously using transcranial Doppler sonography, laser Doppler flowmetry, and thermal measurement systems. Near-infrared spectroscopy appoars to have the potential for noninvasive measurements of cerebral oxygen saturation and mitochondrial oxygen availability. Brain electrical monitoring techniques such as electroencephalography and evoked potentials are sensitive and specific enough to detect changes in neuronal function as a result of cerebral ischemia. Electroencephalographic and evoked potential measurements of the depth of anesthesia and specific electroencephalogram patterns for pharmacodynamic quantification of drug effects may enable the drug dosage to be based on its anesthetic effect.