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The primary function of recombinant activated factor VII (rFVIIa) is to increase thrombin formation which leads to increased fibrin and less “bleeding.” As a result, most of literature utilizes “bleeding” as the outcome measure with respect to rFVIIa. However, we report the actual effect of rFVIIa on changes in hemostatic markers such as prothrombin activation peptide F1.2, thrombin antithrombin complex (TAT), D-dimer, tissue plasminogen activator (tPA), and plasminogen activator inhibitor (PAI) in a neonate after cardiopulmonary bypass. A single dose of rFVIIa caused a 5.5-fold increase in F1.2, 3.5-fold increase in TAT, and a small increase in d-dimer compared to only a 1.5-fold increase, no increase, and a decrease, respectively, in two neonates undergoing the same procedure having not received rFVIIa. The patterns of change for tPA and PAI were similar.

Elevated levels of circulating procoagulants like tissue factor may increase the risk of systemic coagulation activation, thrombin generation, and consumptive coagulopathy. I measured procoagulant activity in plasma by using a clot-based assay that incorporated normal plasma to replace missing factors, corn trypsin inhibitor to block contact activation, factor VIIa to improve sensitivity to tissue factor activity, and anti–tissue factor antibodies to measure tissue factor–specific activity. Procoagulant activity was evaluated in 58 trauma patients. Trauma patients without coagulopathy (n = 50) showed 5-fold higher procoagulant activity than did control subjects (P < .001), whereas trauma patients with coagulopathy (n = 8) showed 10-fold higher activity than control subjects (P < .001) and 2-fold higher activity than trauma patients without coagulopathy (P = .03). In control subjects, tissue factor activity was below the detection limit of the assay. Tissue factor activity was 3- to 4-fold higher in trauma patients with coagulopathy vs patients without coagulopathy (P = .002). Trauma patients with coagulopathy have increased circulating tissue factor activity. [ABSTRACT FROM AUTHOR]

We optimized fluorogenic thrombin-generation assays with regard to sample volume, calibration, analytic corrections, and activation reagents. Lower sample volumes (40 vs 80 microL) were associated with better recovery of thrombin activity, lower interference due to absorbance of light, and higher total thrombin generation (area under the curve), even using internal standards to calibrate plasma samples. With lower sample volumes, there was no advantage to internal calibration of samples without obvious interference (hemolysis). Previously developed corrections for measured vs expected fluorescence units, residual thrombin-alpha(2)-macroglobulin activity, and hemolysis improved the analytic accuracy of the assay. An optimized assay with a 40-microL sample volume, analytic corrections, and a corn trypsin inhibitor to block contact activation showed that 0.6 pmol/L tissue factor activator was better than 5 pmol/L at differentiating healthy subjects from patients with sepsis while demonstrating good reproducibility (area under the curve, 4% within-run and 7% between-run coefficient of variation). [ABSTRACT FROM AUTHOR]