Thoracic Aorta Occlusion-Reperfusion Decreases Hemostasis as Assessed by Thromboelastography in Rabbits

Perioperative hemorrhage and thrombosis are serious complications associated with major vascular surgery. We hypothesized that thoracic aortic occlusion-reperfusion in rabbits would adversely affect hemostasis as assessed by thromboelastographic variables (reaction time, α angle and G [a measure of clot strength]). Isoflurane-anesthetized rabbits underwent either sham operation (n = 10) or 30 min of aortic occlusion followed by 90 min of reperfusion (n = 10). Blood samples (350 μL) were exposed to 10 μL of either 0.9% NaCl or cytochalasin D (a platelet inhibitor, 10 μM final concentration) and analyzed for 1 h by using thromboelastography after 30 min of postpreparation equilibration and at 30 and 90 min of reperfusion. Aortic occlusion-reperfusion resulted in a significant (P < 0.05) increase in reaction time, decrease in α angle, and decrease in G at 30 and 90 min of reperfusion compared with the sham-operated group. The decrease in hemostatic function after aortic occlusion-reperfusion was observed to the same degree in samples with or without platelet inhibition. There were no significant differences in platelet concentration between the sham-operated and aortic occlusion-reperfusion groups. Aortic occlusion-reperfusion decreased hemostatic function in rabbits primarily by decreasing the coagulation factor-dependent, platelet-independent contribution to clotting. Implications Thoracic aortic occlusion-reperfusion decreased hemostatic function in rabbits primarily by decreasing the coagulation factor-dependent, platelet-independent contribution to clotting. This decrease in hemostatic function may contribute to hemorrhagic complications associated with major vascular surgery.