Table 1.

Factors Influencing Measurement of Activated Clotting Time

Patient

1. Preoperative medications •Vitamin K epoxide reductase inhibitors (eg, warfarin) •Platelet inhibitors (eg, cyclooxygenase inhibitors, P2Y12 receptor inhibitors) •Oral direct thrombin inhibitors (eg, dabigatran) •Factor Xa inhibitors (eg, apixaban, rivaroxaban) •Glycoprotein IIb/IIIa inhibitors (eg, abciximab, eptifibatide, tirofiban) 2. Platelet count and function 3. Factor deficiencies •Intrinsic pathway (eg, factors XII, XI, VII, VIII and kallikrein) •Common pathway (eg, factors V, II) •Antithrombin •Fibrinogen 4. Proinflammatory states (eg, antiphospholipid syndrome, vasculitis, DVT, DIVC)

Cardiopulmonary bypass

1. Hypothermia 2. Hemodilution

Method of evaluating ACT

1.Type of activator (eg, diatomaceous earth, kaolin, silica, glass) 2. Technical method for ACT measurement (eg, mechanical optical, photo-optical, amperometric, photomechanical) 3. Derived or real time ACT

Intraoperative anticoagulant

1. Source of heparin (eg, bovine, porcine) 2. Parenteral direct thrombin inhibitors (eg, bivalirudin, argatroban)

Abbreviations: ACT, activated clotting time; DIVC, disseminated; DVT, deep vein thrombosis; intravascular coagulopathy.