Cerebral hypoxia is a major contributor to poor neurologic outcome in a variety of clinical cases but its detection remains problematic. Measurement of cerebral oxygenation is widely used to assess the balance between cerebral metabolic supply and demand although standard bedside methods of measuring cerebral oxygenation have significant limitations. Near-infrared spectroscopy (NIRS) is a noninvasive bedside technology that offers the potential for cerebral monitoring over multiple regions of interest. The technique of NIRS is based on the principle of light attenuation by the chromophores oxyhaemoglobin (HbO2), deoxyhaemoglobin (Hb) and cytochrome oxidase. Changes in the detected light levels can therefore represent changes in concentrations of these chromophores. The clinical availability of non-invasive NIRS-based cerebral oximetry devices represents a potentially important development for the detection of cerebral ischaemia. This review provides a synopsis of the mode of operation, current limitations and confounders, clinical applications, and potential future uses of such NIRS devices.
Keyword(s): brain, ischaemia, oximetry, oxygen, saturation.
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