Extravascular fibrinogen degradation in experimental burn wounds: a source of fibrin split products

Utilizing a 40 percent flame-burned canine model, serial aliquots of burn-wound edema and simultaneous plasma samples were collected for 26 hours after burn, following the injection of 100 muc of 125I-tagged fibrinogen. Both edema fluid and plasma samples were analyzed for radioactivity. In addition, radioactivity in the supernatant was reassayed after sequential in vitro addition of thrombin, protamine sulfate (PS), and trichloroacetic acid (TCA) to each sample. Plasma and edema fibrinogen and fibrin split product concentrations were measured directly. PS and TCA precipitable protein concentrations were calculated. Early post-burn edema radioactivity appeared primarily in the fibrinogen fractions where edema fibrinogen concentration was measured at almost 30 percent of the simultaneous plasma concentration. Late post-burn edema radioactivity (24 to 27 hours) was associated with the PS precipitable protein fraction (soluble fibrin monomer). Fibrin split product concentration increased in both plasma and edema during the study period. These observations allowed construction of a hypothesis to explain the post-burn elevation in plasma fibrin split product concentration noted in burned patients and strongly suggested that the abnormally elevated plasma fibrin split concentrations resulted from extravascular plasmin digestion of fibrinogen.