Brain Oxygenation Monitoring in Patients Undergoing Coronary Artery Bypass Surgery

• Cognitive function measured by neurocognitive tests administered in the preoperative, immediate postoperative, and three months postoperative periods
  

• Relationship of intraoperative risk data to postoperative cognitive function
  

This study represents a prospective, randomized assessment of the potential clinical and economic benefit to be derived from the continuous non-invasive monitoring of regional cerebral oxygen saturation (rSO2) during cardiac surgery employing cardiopulmonary bypass (CPB). Previous studies have shown that low rSO2 values obtained during surgery are highly associated with postoperative frontal lobe dysfunction, cognitive declines, disorientation, and other clinical indices of prolonged recovery. Low rSO2 values are thought to reflect the development of tissue hypoxia within susceptible regions of the cerebral cortex during the non-pulsatile perfusion of CPB. Rapid detection and correction of such episodes should help avoid regional hypoxia and its attendant postoperative sequelae. This study will assess neurologic, psychometric, and quality of life markers of brain dysfunction which could result from CPB. Each study patient will be assessed both pre- and postoperatively (pre-hospital discharge and at three months) for neurologic and neurocognitive dysfunction.

Comparison(s): Intervention versus control group. Patients assigned to the intervention rSO2-monitored group will be managed with conservative measures designed to maintain the rSO2 value at, or above, its preoperative value. Such measures include increases in pump flow, blood pressure, anesthetic dose, arterial oxygen tension, carbon dioxide tension, and hematocrit. Those patients in the control group will be managed according to current established practice. Although rSO2 is also recorded in this group, the monitor's readings are blinded.