HEPARIN FREQUENTLY IS ADMINISTERED to provide anticoagulation for prevention of thrombosis and ischemia during vascular surgery. Heparinization during major vascular procedures in which an arterial clamp is applied is universal; however, monitoring the anticoagulant effect of heparin is not routine at all medical centers. Heparin effect may be monitored in a number of ways. Initial clotting time measurements are accomplished by placing whole blood in a glass tube and tilting the tube until blood fluidity is lost. The Lee-White whole blood clotting time relies upon the glass tube to “activate” the clotting cascade and catalyze clot formation. 1 Kaplan J.A. Reich D. Savino J. Cardiac Anesthesia.6th ed. Elsevier, St. Louis, MO2011: 496-516 Google Scholar With increasing amounts of heparin, however, this test is time consuming and labor intensive.