In 11 men undergoing infrainguinal bypass surgery, simultaneous blood samples were analyzed by use of sensitive markers of thrombin activity (fibrinopeptide A,FPA) and platelet behavior (β-thromboglobulin, β-TG), as well as conventional clotting times. FPA levels were consistently higher in the venous outflow from the ischemic limb compared with the arterial inflow (p < .01), while no venoarterial difference was noted for β-TG. This suggests that there is increased thrombin generation, but not platelet activation localized to the ischemic limb. After a mean dose of 6800 units of heparin given during surgery, FPA levels fell significantly (p < .03), and the activated clotting time (ACT) was prolonged to 230 to 260 sec, but β-TG levels did not change. Anticoagulation during lower extremity vascular surgery may be usefully monitored by the activated clotting time because an ACT longer than 250 sec is correlated with lower FPA levels (less than 10 ng/ml), reflecting significant inhibition of coagulation.
Sobel, M., Gervin, C. A., Qureshi, D. G., & Greenfield, L. J. (1987). Coagulation responses to heparin in the ischemic limb: Assessment of thrombin and platelet activation during vascular surgery. Circulation, 76(3 II SUPPl.), 8–13. https://doi.org/10.1016/0741-5214(88)90423-5