Cerebral Oximetry Monitoring in Cardiac Surgery: A Technology for Non-invasive Brain Monitoring

Brain injury is a common complication in cardiac surgery. Cerebral oximetry has been shown to reduce major organ dysfunction resulted by cardiac surgery. Monitoring of cerebral perfusion during cardiac surgery is needed to reduce neurological complications. The technology of near-infrared spectroscopy (NIRS) to assess cerebral oxygenation levels was introduced 40 years ago and have been used clinically for over 20 years. Non-invasive cerebral oximetry uses transcranial near-infrared spectroscopy to measure oxygen saturation within a small area of the cerebral cortical vasculature. Oximeters are instruments that use the absorption of light to measure the concentration of different types of hemoglobin. These devices are widely used in various units as a guide to therapeutic interventions to indicate the oxygenation status of patients. Cerebral oximetry is a non-invasive tool for continuous monitoring of cerebral perfusion. However, in different conditions, this technology may show the degree of oxygen saturation as false, high or low. Although pulse oximeters are useful tools for monitoring patient oxygenation, there have been few studies on the accuracy and precision of pulse oximeter in specific clinical conditions and in the intensive care unit. On the other hand, cerebral oxygenation monitoring using near infrared spectroscopy detects changes in oxygenation earlier than pulse oximetry. This review was performed to describe current information on cerebral oximetric monitoring in cardiac surgery and its effect on cardiovascular surgery outcome as well as the factors which have restricted its more widespread application. Because oxygen saturation monitoring by NIRS and using the brain as an index organ for perfusion in cardiac surgery has been associated with fewer incidences of major organ dysfunction and shorter duration in the intensive care unit.