Fig. 5From: Coagulative safety of epidural catheters after major upper gastrointestinal surgery: advanced and routine coagulation analysis in 38 patients Boxplots show pre- to postoperative changes in coagulation factor activities. Factors II, VII, IX and X are vitamin K-dependent. Dashed lines indicate reference intervals, brackets indicate significant differences between pre- and postoperative results *P < 0.05; **P < 0.01Back to article page