Renal oxygen saturation
REGRESSION
The root-mean-square error accuracy was 7.7% for flank oxygen saturation and renal reference. The mean bias was − 4.9 ± 5.2%, resulting in limits of agreement from − 15.0 to 5.2% (Fig. 
Bland-Altman plot for renal oxygen saturation. The solid horizontal lines represent the bias (mean) and limits of agreement (mean ± 1.96 SD) between flank oxygen saturation and renal reference oxygen saturation. The dashed lines represent the 95% CI of the bias and limits of agreement. The slope of the regression of differences on averages was significant (slope = -0.58, p < 0.0001)