Anticoagulation Monitoring during Cardiac Surgery 

Abstract

The literature does not consistently support the importance of anticoagulation monitoring techniques during CPB. This is best reflected by studies that have evaluated the impact of the ACT method on blood loss and transfusion outcomes. Inconsistent findings from studies that evaluated the impact of ACT monitoring may be related to either suboptimal study design (i.e., retrospective, unblinded, nonrandomized) or possibly the diagnostic inprecision of the ACT method used in these studies. There are a small number of well-controlled studies, some of which suggest that bleeding and transfusion outcomes can be improved by refining heparin monitoring techniques, either by sustaining better anticoagulation during CPB or by optimizing protamine doses (i.e., when empiric protocols result in excessive protamine doses). More well-controlled studies are needed to better define the importance of anticoagulation management during CPB.

Monitoring of heparin and its low-molecular-weight analogs by silicon field effect

“…The data were successfully fitted to a Langmuir isotherm with K d ϭ 44 nM (0.12 units͞ml), with the sensitive region ranging over two orders of magnitude, from Ϸ0.01 to 1 units͞ml. Heparin doses given to patients typically range from 2 to 8 units͞ml during bypass surgery and an order of magnitude lower for postsurgical therapy (1). The protamine sensor is therefore capable of detecting heparin at and below clinically relevant concentrations.…”

“…T he complications associated with regulating blood coagulation present major health concerns that can be managed by careful administration and monitoring of anticoagulant drugs (1,2). In a clinical setting, it is critical to maintain anticoagulant levels that are sufficient to prevent thrombosis yet low enough to avoid bleeding risks.…”

“…Standard clinical procedures for monitoring anticoagulant activity of heparin are based on measuring the activated clotting time or activated partial thromboplastin time (1,19). Although widely used, these tests often fail to provide the actual heparin level because the clotting time can be affected by additional factors commonly encountered during surgery, such as hypothermia or hemodilution, and abnormal levels of clotting factors (1,20,21).…”

“…Although widely used, these tests often fail to provide the actual heparin level because the clotting time can be affected by additional factors commonly encountered during surgery, such as hypothermia or hemodilution, and abnormal levels of clotting factors (1,20,21). It has been demonstrated that careful patient-specific assessment of heparin levels would reduce the occurrence of anticoagulation complications (20,22).…”

“…There have been extensive efforts to develop new devices suitable for routine measurement of heparin levels in clinical settings (1,23). Various approaches such as quartz crystal microbalance, surface plasmon resonance, ion-sensitive fieldeffect transistor, and membrane-based ion-selective electrode involve either protamine or synthetic cationic polymers as heparin probes, and they are based on either surface affinity capture or an automated heparin titration (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34).…”