Objective
A recent prospective randomized clinical sepsis trial (Kybersept study) shows a reduction in 90-day mortality by antithrombin (ATIII) only in the prospectively defined subgroup of patients without simultaneous heparin treatment. To investigate whether this clinically observed heparin-ATIII antagonism is caused by a heparin-related reversal of ATIII effects on the microcirculation during endotoxemia, experimental ATIII administration was combined with administration of different heparins at a clinically relevant dose.