Comparison of the thrombogenicity of internationally available fibrin sealants in an established microsurgical model

Previous studies comparing the thrombotic complications of cryoprecipitated fibrin sealant containing bovine thrombin on microvascular venous anastomo ses in a rat epigastric free flap model revealed deleterious outcomes regar ding flap survival with higher concentrations of topical bovine thrombin. T his study was designed to compare three internationally available fibrin se alants, one experimental fibrin monomer sealant that does not require throm bin, and human thrombin alone as to their effects on the survival of an est ablished rat epigastric free flap model. Ninety Sprague-Dawley rats (400 to 600 g) were prepared for abdominal surgery, and an epigastric-based skin f lap was raised. The single vein draining the flap was clamped, divided, and reconnected using standard microvascular suturing techniques. Before relea se of the clamps, the chosen additive was applied precisely to the anastomo sis. Additional material was then added to the raw Surface of the flap. The animals were divided into seven treatment groups, each receiving 1 ml of c ommercial or investigational fibrin sealant or human thrombin alone: one co ntrol group receiving no additive treatment, four fibrin sealant groups rec eiving treatment with commercial or investigational fibrin sealant preparat ions, and two groups receiving different concentrations (500 IU/ml and 1000 IU/ml) of human thrombin applied to the anastomoses and the surrounding ti ssue. Fap survival was assessed at 7 days postoperative. ly. This study sup ports the contention that microvascular free flap survival based on microva scular venous anastomotic patency was adversely effected by high concentrat ions of thrombin. Lower concentrations (500 IU/ml and less) of thrombin did not seem to affect flap survival. One test product was composed of a fibri n monomer sealant, which obviates the need for the thrombin additive. This group's survival rate was not statistically different from that of the cont rol group. Thus, for microvascular anastomoses, lower concentrations of thr ombin or a sealant devoid of thrombin seem to be best for microvascular ana stomotic patency.