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Patients having surgical procedures are at risk for anoxia that may cause cognitive impairment. Continuous monitoring of cerebral oxygenation and perfusion with an instrument such as a cerebral oximeter is desirable.The data it provides give insight into the cause of the cerebral insults along with the cerebral response to specific interventions, all of which could help prevent damage to the brain.This critical review of the literature on the efficacy, mechanics, and usefulness of the cerebral oximeter will be helpful to anesthesia providers in evaluating the controversy surrounding its use. A comprehensive understanding of the factors involved in cerebral perfusion and available equipment, such as the cerebral oximeter to monitor cerebral oxygenation, allows anesthetists to provide the best protection for the brain.
Keywords: Cerebral oximetry, cerebral perfusion, nearinfrared spectroscopy.
Objectives
At the completion of this course, the reader should be able to:
1. Summarize the physiology of cerebral oxygenation and perfusion.
2. Compare and contrast the methods currently used to monitor cerebral perfusion.
3. Describe how near-infrared spectroscopy monitors measure cerebral oxygen saturation.
4. Identify advantages and disadvantages of the cerebral oximeter.
5. Explain clinical evidence that supports the efficacy of the cerebral oximeter.
Introduction
Although advances in anesthesia have been achieved, one problem that remains a source of concern is cerebral injury. Intraoperative cerebral injury, including stroke and brain damage, represents the single largest percentage (17%) of malpractice claims.1 Refined diagnostic techniques have shown evidence of neurologic sequelae suggesting that damage might have occurred during or immediately after surgical procedures, which suggests that current methods of cerebral monitoring are inadequate. This concern has resulted in research directed toward development of monitoring techniques and new strategies for cerebral protection and for the early detection of cerebral dysfunction. Standard methods of monitoring do not provide a direct measure of oxygen levels in the brain. In 1996, Samra et al2 suggested that the near-infrared spectroscopy (NIRS) cerebral oximeter may be clinically useful during open-heart surgery, neurosurgical procedures, and management of patients with head injury. The cerebral oximeter is a near-infrared laser device that measures brain oxygen levels in a mixture of arteries, capillaries, and veins. It is noninvasive and offers real-time information for measuring cerebral oxygenation and, indirectly, cerebral perfusion. Taillefer and Denault3 concluded that this...