Cerebral oximetry during cardiac surgery: the association between cerebral oxygen saturation and perioperative patient variables.

OBJECTIVE

This "real-world" study was designed to assess the patterns of regional cerebral oxygen saturation (rSO(2)) change during adult cardiac surgery. A secondary objective was to determine any relation between perioperative rSO(2) (baseline and during surgery) and patient characteristics or intraoperative variables.

DESIGN

Prospective, observational, multicenter, nonrandomized clinical study.

SETTING

Cardiac operating rooms at 3 academic medical centers.

PARTICIPANTS

Ninety consecutive adult patients presenting for cardiac surgery with or without cardiopulmonary bypass.

INTERVENTIONS

Patients 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 RESULTS

The average baseline (before induction) rSO(2) was 63.9 ± 8.8% (range 41%-95%); preoperative hematocrit correlated with baseline rSO(2) (0.48% increase for each 1% increase in hematocrit, p = 0.008). The average nadir (lowest recorded rSO(2) for any given patient) was 54.9 ± 6.6% and was correlated with on-pump surgery, baseline rSO(2), and height. Baseline rSO(2) 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 rSO(2)).

CONCLUSIONS

In cardiac surgical patients, lower baseline rSO(2) value, on-pump surgery, and height were significant predictors of nadir rSO(2), whereas only baseline rSO(2) was a predictor of postoperative length of stay. These findings support previous research on the predictive value of baseline rSO(2) on length of stay and emphasize the need for further research regarding the clinical relevance of baseline rSO(2) and intraoperative changes.