Polymyxin B hemoperfusion (PMX-HP) is mainly used to remove endotoxins in septic shock patients with intra-abdominal infections. Because of the concerns of postoperative bleeding, physicians may hesitate to use anticoagulation in patients with septic shock within a few hours after an abdominal operation. We developed a heparin dosing score protocol for heparin dosage adjustment. The purpose of the study is to examine the safety and efficacy of the heparin dosing score protocol.