Mortality Predicted by Preinduction Cerebral Oxygen Saturation After Cardiac Operation

BACKGROUND:

An intraoperative decline in regional cerebral oxygen saturation (rSO2) has been associated with postoperative injury to the central nervous system. Wide individual variation in steady-state cerebral oxygen saturation limits the clinical use of rSO2 to monitoring during anesthesia and surgical procedures. Recently, low preoperative rSO2 has been proposed as a predictor of adverse postoperative outcomes in cardiovascular operations. We compared the sensitivity and specificity of preinduction rSO2 as a predictor of adverse operative events and compared this to the widely accepted risk index developed by the Society for Thoracic Surgeons.

METHODS:

2,097 consecutive white patients who underwent cardiac operations from 2010 through 2012 were included. In 1,496 patients (group 1) the preinduction rSO2 was equal to or greater than 60%, whereas in the remaining 601 patients (group 2) it was below 60%. We compared the predictive accuracy of preinduction rSO2 with that of the STS mortality risk score by means of standard statistical techniques, including a receiver operating curve characteristic analysis.

RESULTS:

Patients with a preinduction rSO2 below 60% had significantly higher STS mortality risk scores than did patients with an rSO2 equal to or greater than 60% (2.0 vs 4.0, p < 0.001). Those with an rSO2 below 60% experienced higher operative mortality (p < 0.001) and after adjustment this determination emerged as an independent predictor of increased mortality (p < 0.001). Receiver operating characteristic curve analysis demonstrated that the rSO2 was slightly less accurate as a mortality predictor (area under the curve: 0.71 vs 0.85).

CONCLUSIONS:

Measurement of rSO2 is considerably less complex than calculation of the STS score and is only slightly less accurate as a predictor of operative mortality. It may be useful when the STS mortality risk score cannot be calculated.