Diagnostic Accuracy Study of a Point-of-Care Test for Coagulation Function: CoaguChek System Versus Standard Laboratory Tests in Cardiac Surgery Requiring Cardiopulmonary Bypass

Laboratory evaluation of blood clotting is widely used in perioperative medicine, either by conventional technique (prothrombin time - PT/INR, Activated Partial Thromboplastin Time - aPTT, fibrinogen dosage and platelet count) or by the Point of Care method (Thromboelastogram ) - notably in surgical procedures with the possibility of severe volume loss (cardiovascular, oncological, trauma, etc.).

The prothrombin time (PT) is a general assessment of the integrity of the extrinsic and common pathway of coagulation. It determines the time of formation of the fibrin clot. The INR/RNI (International Normalized Ratio) is calculated from the PT and is intended to establish valid comparisons regardless of the type of PT reagent (known as thromboplastin) used by different clinical laboratories. The INR is indicated for evaluating the integrity of the extrinsic (factor VII*) and common pathway (fibrinogen and factors II*, V and X*), and for monitoring the anticoagulant effect of an anti-vitamin K agent (warfarin), capable of inhibiting the synthesis of vitamin K dependent factors (II, VII, IX, X, proteins C and S).

Today, due to its safety, sensitivity and speed, the thromboelastogram is recommended as the method of choice for assessing hemostasis in a surgical setting. However, because it is still not widespread in many centers, mainly due to its high cost, many hospitals are limited to the use of traditional laboratory methods which, despite their undeniable reliability, require more time for their execution and release of results.

In cardiac surgery with cardiopulmonary bypass (CPB), the use of prime solution to fill the CPB circuit results in hemodilution of coagulation factors, with factor I (fibrinogen) being one of the most affected, but not the only one. Each abnormality detected requires a specific action. Thus, the activated clotting time (ACT) is normalized with the administration of protamine. Thrombocytopenia and/or platelet dysfunction, with platelet concentrate infusion. Abnormalities in clotting factors, with administration of the specific factor, eg fibrinogen, either by factor concentrate, cryoprecipitate or plasma. It is at this moment that a quick assessment of hemostasis, in a global and individualized way at the same time, is necessary.

More than a decade ago, devices appeared on the market designed to help patients using warfarin to maintain their anticoagulation within parameters established for each case, providing safety, speed and comfort. Using a reagent strip and a drop of blood, evaluating the INR has become as simple as evaluating capillary blood glucose for diabetic patients. In just a few seconds, INR assessment can show significant changes in the extrinsic coagulation pathway, an important step to help with rapid decision-making in surgical environments. The Coaguchek Device, validated and used for outpatient management of patients using Warfarin, presents valuable characteristics for this purpose (simplicity, speed, safety), also important in the context of intraoperative decision-making. There are few reports in the literature on the use of the Coaguchek device in surgery and on the reliability of the data obtained through its use.