Cerebral Oximetry During Cardiac Surgery: The Association Between Cerebral Oxygen Saturation and Perioperative Patient Variables

ObjectiveThis “real-world” study was designed to assess the patterns of regional cerebral oxygen saturation (rSO2) change during adult cardiac surgery. A secondary objective was to determine any relation between perioperative rSO2 (baseline and during surgery) and patient characteristics or intraoperative variables.DesignProspective, observational, multicenter, nonrandomized clinical study.SettingCardiac operating rooms at 3 academic medical centers.ParticipantsNinety consecutive adult patients presenting for cardiac surgery with or without cardiopulmonary bypass.InterventionsPatients received standard care at each institution plus bilateral forehead recordings of cerebral oxygen saturation with the 7600 Regional Oximeter System (Nonin Medical, Plymouth, MN).Measurements and Main ResultsThe average baseline (before induction) rSO2 was 63.9 ± 8.8% (range 41%-95%); preoperative hematocrit correlated with baseline rSO2 (0.48% increase for each 1% increase in hematocrit, p = 0.008). The average nadir (lowest recorded rSO2 for any given patient) was 54.9 ± 6.6% and was correlated with on-pump surgery, baseline rSO2, and height. Baseline rSO2 was found to be an independent predictor of length of stay (hazard ratio 1.044, confidence interval 1.02-1.07, for each percentage of baseline rSO2).ConclusionsIn cardiac surgical patients, lower baseline rSO2 value, on-pump surgery, and height were significant predictors of nadir rSO2, whereas only baseline rSO2 was a predictor of postoperative length of stay. These findings support previous research on the predictive value of baseline rSO2 on length of stay and emphasize the need for further research regarding the clinical relevance of baseline rSO2 and intraoperative changes.