Antiplatelet and Anticoagulant Prophylaxis and Postoperative Blood Loss in Cardiac Surgery

Fibrinogen supplementation ex vivo increasesclot firmness comparable to platelet transfusion in thrombocytopenia

BACKGROUND

Fibrinogen concentrate can improve clot firmness and offers a better safety profile than platelet concentrates. Reduction or avoidance of blood transfusions represents a strategy to reduce associated risks. We investigated whether supplementation of fibrinogen concentrate ex vivo can compensate for clot strength as compared with platelet transfusion in vivo METHODS: One hundred patients in need of platelet transfusion (PT) were enrolled. Blood samples were collected immediately before PT and at 1 h and 24 h after PT. Fibrinogen concentrate was added to these citrated whole blood samples at concentrations of 50, 100, 200 and 400 mg kg^-1 and the maximum clot firmness (MCF) was analysed using ROTEM thromboelastometry.

RESULTS

Fibrinogen supplementation increased MCF significantly and dose-dependently before and after PT. The effect of fibrinogen concentrate (equivalent to doses of 100 and 200 mg kg^-1) ex vivo was comparable to that of PT in vivo, whereas 400 mg kg^-1 fibrinogen significantly improved MCF compared with PT (P < 0.001).

CONCLUSIONS

Fibrinogen concentrate can match the effect of PT on MCF in thrombocytopenia. This potential alternative haemostatic intervention should be evaluated in clinical trials.

The effect of fibrinogen concentrate on thrombocytopenia

OBJECTIVES

The hypothesis that the administration of fibrinogen concentrate enables restoration of impaired clot formation and increased bleeding in severe thrombocytopenia was tested.

METHODS

Thirty pigs were anesthetized, instrumented for blood sampling (routine coagulation tests, modified thrombelastography ROTEM, hemodynamic monitoring and platelet apheresis to a target below 30 x 10(9) L(-1) after splenectomy. Thereafter 10 each of the animals randomly received two apheresis platelet concentrates, 250 mg kg(-1) fibrinogen concentrate or normal saline solution. A standardized liver injury was subsequently inflicted to induce uncontrolled hemorrhage.

RESULTS

Median (Q1, Q3) clot firmness increased significantly more in thrombocytopenic pigs after fibrinogen administration (42 mm (41, 43) to 60 mm (57, 63)) than following platelet transfusion (40 mm (37, 45) to 52 mm (48, 55), P = 0.0004) or placebo (45 mm (41, 48) to 45 mm (43, 46), P = 0.0002). Median blood loss velocity after liver injury was significantly less with fibrinogen (33 mL min(-1), P = 0.005) than with platelets (62 mL min(-1), P = 0.037) or saline (84 mL min(-1), P = 0.005), and median survival time after liver injury was 55 min in the fibrinogen, 26 min in the platelet (P = 0.035) and 19 min in the saline group (P = < 0.0001).

CONCLUSIONS

These data show for the first time that impaired clot formation during thrombocytopenia improves with administration of fibrinogen concentrate, which results in a slowdown of blood loss and prolonged survival.