Hemostatic changes after crystalloid or colloid fluid administration during major orthopedic surgery: the role of fibrinogen administration.

BACKGROUND: To explore whether disturbed fibrin polymerization is the main problem underlying dilutional coagulopathy and can be reversed by fibrinogen administration, we conducted a prospective study using modified thrombelastography (ROTEM).

METHODS: Sixty-six orthopedic patients randomly received modified gelatin solution, hydroxyethyl starch 130/0.4, or exclusively Ringer lactate solution. ROTEM analysis was performed, concentrations of coagulation factors and markers of thrombin generation were measured. Fibrinogen concentrate (Hemocomplettan) was administered (30 mg/kg) when thrombelastographically measured fibrinogen polymerization was critically decreased.

RESULTS: The alpha angle, clot firmness, and fibrinogen polymerization (median [min to max]) significantly decreased in the patients receiving hydroxyethyl starch (area under the curve minus baseline (-5 [-9 to -2]), followed by gelatin solution (-3 [-8 to 0]), with the least reductions seen for Ringer lactate solution (-2 [- 4 to 1]) (colloids versus Ringer lactate P < 0.0001). Thirteen patients in the colloid groups but none in the Ringer lactate group needed fibrinogen concentrate to maintain borderline clot firmness. Activity of FVII, FVIII, FIX, and von Willebrand ristocetin activity decreased significantly with colloids. Thrombelastographically measured coagulation time, molecular markers of thrombin generation, and activity of all other coagulation factors were comparable in all groups.

CONCLUSION: Disturbance of fibrinogen/fibrin polymerization is the primary problem triggering dilutional coagulopathy during major orthopedic surgery. The magnitude of clot firmness reduction is determined by the type of fluid used, with hydroxyethyl starch showing the most pronounced effects. These undesirable effects of intravascular volume therapy can be reversed by increasing fibrinogen concentration by administering fibrinogen concentrate, even during continuing blood loss and intravascular volume replacement.