Monitoring of antifibrinolytic treatment in subarachnoid hemorrhage.

21 patients (aged 28-81 years) with recent subarachnoid hemorrhage (10 saccular aneurysms, 3 arteriovenous angiomas, 8 normal angiograms) were continuously infused with tranexamic acid at a dosage of 5 g daily for up to 14 days. Therapy was surveyed by daily measurement of the available plasminogen activity (aPl) with the chromogenic substrate S-2251 and by a modified bioassay, whereby the concentration of tranexamic acid was determined thrombelastographically and expressed as antifibrinolytic equivalent. In addition, a battery of blood coagulation tests was performed daily. 5 patients died, 1 after postoperative stroke, 3 as a result of general complications during intensive care treatment, but only 1 due to rebleeding. 4 patients were successfully operated during the first week, 1 patient after 2 weeks. aPl fell from 99.2% (SEM 3.0%, n = 21) before treatment to 72.9% (SEM 3.5%, n = 21) after 24 h and to the therapeutic level between 50 and 60% from day 2 on. The mean steady state of the antifibrinolytic equivalent corresponded to about 150 micrograms/ml of tranexamic acid during infusion. Intra- and interindividual changes were relatively small for aPl, when compared with the antifibrinolytic equivalent measured by the bioassay. In 2 elderly patients tranexamic acid infusion had to be terminated because of clinical and laboratory signs of disseminated intravascular coagulation, whereby aPl fell below the therapeutic range, elucidating that this method is a sensitive indicator for a hypercoagulable state and useful for the surveillance of therapy with antifibrinoltic agents.