Table 2. The six rSO2 variables analyzed for each patient.

rSO₂ - Regional cerebral oximetry, AUC - Area under the curve

1.	Preoperative (baseline) rSO2	For each patient awake breathing air
2.	Mean intraoperative rSO2	Mean rSO2 throughout the surgery
3.	Time below preoperative rSO2	AUC for any fall below baseline
4.	Threshold rSO2 minus 10%	AUC for any fall more than 10% below baseline
5.	Threshold rSO2 minus 20%	AUC for any fall more than 20% below baseline
6.	Threshold rSO2 minus 50%	AUC for any fall more than 50% below baseline