Cerebral Oximetry and Neurocognitive Functions in Cardiosurgical Patients

Neurologic complications are major cause of morbidity following coronary artery bypass graft surgery. The neurologic injuries range in severity from subclinical cognitive changes to fatal brain injury and death. These complications represent a big impact on overall morbidity, and mortality in association with increased costs and length of hospital stay. The social impact is also very important with consequences on patients' quality of life. Several studies reported the incidence of cognitive decline after cardiac surgery that ranges from 30 to 80%. The most common etiologies are embolization and hypoperfusion of the brain. The In Vivo Optical Spectroscopy (INVOS) system uses near-infrared spectroscopy (NIRS) and provides noninvasive and continuous information on changes in regional oxygen saturation of blood in the brain (rSO2). When rSO2 decline occurs it can be responded with simple interventions to prevent a brain injury. These interventions include: repositioning of the head or perfusion cannulae, increasing arterial carbon dioxide tension, increasing oxygen inspiration concentration, increasing arterial blood pressure, adjusting pump flow rate, temperature decreasing, increasing of anesthetic depth and blood transfusion. Recent studies reported that intraoperative cerebral oxygen desaturation is associated with early postoperative neuropsychological dysfunction in patients undergoing cardiac surgery. Neurocognitive function can be assessed with battery of standardized neurocognitive tests. Mini Mental State Examination, Color Trail Test, Grooved Pegboard Test are easy to perform bedside tests that test orientation, registration, attention, calculation, recall, language and complex visual-motor coordination.