Abstract
Objective: To evaluate the possible effects of antithrombin III (AT III) concentrate therapy on components of the plasma protease systems in surgical intensive care patients. Design: Open randomised, prospective study. Setting: General intensive care units in secondary and tertiary care hospitals. Subjects: Eighty-three surgical patients with functional plasma activity of AT III below 80% of normal plasma pool value the day after multiple trauma or major abdominal surgery. Interventions: Intravenous infusion of AT III concentrate. Endpoints: To maintain plasma AT III activity above 90% of normal plasma pool value in the therapy group. Measurements and main results: AT III, prothrombin, prekallikrein, kallikrein inhibition, kallikrein-like activity, plasminogen, antiplasmin activity and plasmin-like activity were measured with chromogenic peptide substrate assays. AT III, prothrombin, prekallikrein and plasminogen were reduced on the inclusion day in all patients. The other variables were in the normal range. AT III was in the normal range from day two in the therapy group. Prothrombin, prekallikrein, plasminogen and AT III in the control group revealed a slowly increasing pattern. No significant differences were encountered between the two groups in any of the measured variables except for AT III and prothrombin. Conclusions: In this study both major surgery and trauma induced changes in components of the plasma protease systems. Substitution therapy with AT III concentrate to normalise plasma levels of this antiprotease did not modify these changes.