The Effect of Excess Protamine on Thrombelastography in Vitro

Abstract

The aim of the current study was to assess the direct effect of protamine on conventional thrombelastography in vitro. Protamine was added to blood samples collected from 25 adult cardiac surgical patients prior to the induction of anaesthesia and after separation from cardiopulmonary bypass. The final protamine concentrations were 0 (control), 0.05 mg/ml, 0.1 mg/ml and 0.2 mg/ml (i.e. sufficient to reverse heparin 0, 5, 10 and 20 IU/ml respectively, assuming a 1:1 reversal ratio). In the pre-induction samples, protamine was associated with increases in r time and reductions in maximum amplitude (P<0.01). After bypass, the control samples demonstrated a heparin effect as expected, which was corrected by the addition of protamine 0.05 mg/ml. However, the higher concentrations of protamine were again associated with increases in r time and reductions in maximum amplitude (P<0.01). The results indicate that protamine has a direct anticoagulant effect on conventional thrombelastography in vitro. This effect occurs whether protamine is present alone, or whether protamine is present in excess after neutralization of heparin. Unless this effect is taken into account, excess protamine may confound the interpretation of conventional thrombelastography in cardiac surgical patients.

Impact of protamine dose on activated clotting time and thromboelastography in infants and small children undergoing cardiopulmonary bypass

“…Comparing between and within groups, our findings are consistent with protamine excess induced prolongation of TEG's clot initiation time ( R ) as demonstrated by previous studies . When compared between the groups, with exception of ∆ R (∆ R = R pp − R b), other TEG changes (∆α, ∆ K , and ∆MA) did not reach statistical significance, differing from these previous studies .…”

“… studied effects of a modified heparin‐dosing protocol and proposed protamine neutralization by a factor of 1.5 times the protamine dose for Combined‐EBVs. Previous studies have analyzed the effects of varying amounts of protamine added to blood samples to study its impact on activated clotting time (ACT) or thromboelastography (TEG) . The objectives of this study were to retrospectively examine the impacts of two protamine dosage strategies for infants and children on efficacy of heparin neutralization based on ACT and changes in TEG variables.…”

Thromboelastography: a comparison of polybrene and heparinase for the inactivation of heparin

“…Настоящая работа -это не первая попытка, ставящая целью заменить в методе ТЭГ гепариназу другим реактивом, нейтрализующим гепарин [11,12]. Одним из факторов, ограничивающих широкое применение гепариназы, является ее стоимость.…”

“…Одним из факторов, ограничивающих широкое применение гепариназы, является ее стоимость. В частности, реактив для ТЭГ, созданный на основе протамина, оказался в 100 раз дешевле гепариназы [12].…”