While , 6 % HES 130/0 .4 ( free flex 6 % HES 130/0 .4 , Fresenius Kabi ) infusion was different between the 2 groups , when the patients of group S 's central venous blood oxygen saturation < 75 % or venous-arterial PCO2 in the patients of P group 6 mm Hg , then infused 6 % HES 130/0 .4 .