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Based on the increasing knowledge of defects in haemostasis in patients with sepsis as well as on the non-conclusive results of studies which tried to increase the prognosis by modulating cytokine response of the patients, in the last years the impact of therapeutic modulation of coagulation in sepsis has been investigated. In contrast to the results of phase III studies with the coagulation inhibitors antithrombin and tissue factor pathway inhibitor recombinant human activated protein C (rhAPC) resulted in a significant reduction in mortality for the whole study population. Data analyses showed, that treatment with rhAPC was clinically beneficial especially in patient groups who showed a high mortality in the placebo arm. Inhibition of thrombus formation due to the therapy with natural coagulation inhibitors resulted in an increase of sepsis-imminent haemorrhage, which became significant in some studies. Treatment with antithrombin and heparin resulted in a considerable increase in bleeding complications and on the other hand, may have antagonized the expected effect of antithrombin on the patient's prognosis. Some results suggesting beneficial effects of heparin on patient prognosis in the placebo arms and on the other hand negative effects of heparin in the verum arms -- especially with antithrombin or tissue factor pathway inhibitor -- let to a controversial discussion of the risk/benefit relation of heparin, given in prophylactic doses to patients with severe sepsis. Whereas the impact and optimal application of heparin to patients with severe sepsis needs to be clarified study results with rhAPC resulted in the approval of this therapy and the implementation in the guidelines of the treatment of patients with severe sepsis.

A 38-year-old patient with cerebral P. falciparum malaria was admitted 12 days after a short trip to Kenya. The serum level of tumor necrosis factor (TNF-alpha) was elevated (251 pg/ml). In contrast, Protein C (plasma activity 36.1%; antigen concentration 31.7%) and protein C inhibitor 1 (activity 0.55 U/ml) levels were decreased. This suggested a state of functional activation of the clotting system which was confirmed by elevated levels (4.8 ng/ml) of circulating thrombin-antithrombin-III-complexes (TAT). Protein S (total and free) and coagulation factor IX levels were within normal range. Under successful antiparasitic therapy, TNF-alpha as well as protein C and protein C inhibitor 1 levels returned to baseline within one week. In the context of other studies that demonstrate procoagulant effects of TNF-alpha, it is remarkable that in the case of complicated P. falciparum malaria, an elevated concentration of TNF-alpha can be paralleled by a decreased plasma level of protein C and an increase in TAT suggesting a procoagulant state.

The chemical and physical characteristics of the individual components of the protein-C inhibiting system, protein C, thrombomodulin, protein S and the inhibitor of the activated protein C are summarized in a survey, with their mutual relations and their physiological impact on the course of the coagulating and fibrinolytic systems being represented. Finally, the clinical implications of a hereditary and acquired protein C deficiency, of a diminished protein S level and a lowered inhibitor of the activated protein C are discussed. The complications caused by a rapid decline of protein C values after administration of coumarin derivates are referred too.