Both postoperative delirium (PD) and postoperative cognitive dysfunction (POCD) are well known complications seen in elderly patients after cardiac surgery. The etiologies of PD and POCD are unknown, but cerebral ischemia remains a prime candidate. Attempts to correlate reduced levels of systemic oxygenation (i.e. SpO2) with the development of PD/POCD have been to date disappointing.
We believe that cerebral oximetry, a noninvasive technology that continuously monitors cerebral tissue oxygen saturation (SctO2), will enable us to answer the question of whether or not a correlation exists.
The availability of an absolute cerebral oximeter (FORE-SIGHT), with its ability to establish and manipulate threshold values for SctO2, provides us the opportunity to assess the relationship between cerebral oxygenation and the development of neurocognitive complications.
We propose a randomized, masked trial of 120 patients, adequately powered to assess the following:
- Is there an association between deficits in cerebral oxygenation and the occurrence of PD at some time in the 1st 5 days after the operation?
- Is there an association between deficits in cerebral oxygenation and changes in POCD scores shortly (5 days) after the operation and/or 4-6 weeks later? We hypothesize that individually tailored patient management guided with intraoperative and postoperative absolute cerebral oximetry monitoring using a tailored protocol designed to maintain SctO2 values above a specific threshold will result in improved neurocognitive outcomes in geriatric patients undergoing cardiac surgery.