Use of the Plasma Thrombin Time to Assess the Adequacy of in Vivo Neutralization of Heparin: Comparative Studies Following Operations Employing Extracorporeal Circulation

Abstract

1. The dosage of protamine necessary for the postoperative neutralization of heparin, used as anticoagulant during extracorporeal circulation, was studied in 25 patients by means of both the protamine titration test and the plasma thrombin time. 2. The plasma thrombin time was found to be far more sensitive in the detection of small quantities of residual heparin than was the protamine titration test, which failed to demonstrate significant quantities of circulating heparin. 3. Adequate neutralization of circulating heparin was achieved when an initial postoperative protamine dose of 1.5 times the calculated residual heparin was given and followed by additional protamine when indicated by the result of the plasma thrombin time. 4. No toxic effects of protamine were noted on such a dosage schedule.

Heparin–protamine balance after neonatal cardiopulmonary bypass surgery

“…The thrombin time, has a long history of diagnostic use in the clinical laboratory, and is particularly sensitive to heparin [30;31] and its reversal with protamine [30;32]. In the TFCK, addition of increasing amounts of heparin to adult plasma progressively decreased fibrin formation with complete inhibition at 0.01 U/mL and above (Fig.…”

“…The thrombin time assay has been used in clinical laboratories to reliably measure plasma heparin for decades [30]. The main difference between the TFCK and the thrombin time assay it that the former measures the kinetics of fibrin clot formation while the latter measures the time to fibrin clot formation.…”

Heparin‐like anticoagulant associated with systemic candidiasis

“…The most unusual component of this coagulopathy was the anticoagulant that arose in the midst of this very complicated clinical setting. The heparin-like nature of this substance was initially suggested by the prolongation of the thrombin clotting time, which normalized after the addition of toluidine blue (a cationic dye that binds to heparin) [19] but not by mixing with normal plasma (Table I). Paradoxically, however, both in vivo and in vitro the anticoagulant was remarkably insensitive to protamine sulfate, a potent heparin antagonist ( Fig.…”