There was also a significant difference in mean volatile anesthetic administration ( minimum alveolar concentration ) : 0.98 vs 0.64 ( mean difference -0.35 [ CI95 , -0.44 to -0.26 ] , P < 0.001 ) and target propofol concentrations : 4.0 vs 3.1 g/mL ( mean difference -0.8 [ CI95 , -1.2 to -0.3 ] , P = 0.004 ) .