The Misunderstood Coagulopathy of Liver Disease: A Review for the Acute Setting

Abstract

The international normalized ratio (INR) represents a clinical tool to assess the effectiveness of vitamin-K antagonist therapy. However, it is often used in the acute setting to assess the degree of coagulopathy in patients with hepatic cirrhosis or acute liver failure. This often influences therapeutic decisions about invasive procedures or the need for potentially harmful and unnecessary transfusions of blood product. This may not represent a best-practice or evidence-based approach to patient care. The author performed a review of the literature related to the utility of INR in cirrhotic patients using several scientific search engines. Despite the commonly accepted dogma that an elevated INR in a cirrhotic patient corresponds with an increased hemorrhagic risk during the performance of invasive procedures, the literature does not support this belief. Furthermore, the need for blood-product transfusion prior to an invasive intervention is not supported by the literature, as this practice increases the risk of complications associated with a patient's hospital course. Many publications ranging from case studies to meta-analyses refute this evidence and provide examples of thrombotic events despite elevated INR values. Alternative methods, such as thromboelastogram, represent alternate means of assessing in vivo risk of hemorrhage in patients with acute or chronic liver disease in real-time in the acute setting.

Figure 1

Example of thromboelastogram analysis curve (adapted from Stravitz et al, 201226). r – measured in minutes, the reaction time (r) represents the latency period between the initiation of the reaction and the initiation of fibrin formation, represented by k; k – measured in minutes, the kinetic time (k) represents the time required to reach a clot strength of 2mm; α-angle – measured in degrees, corresponds to kinetics of clot formation; a steeper angle corresponds to a more rapid rate of clot formation. Maximum amplitude – measured in mm, represents the maximum clot strength and is a function of both platelet count / function and fibrinogen concentration; Lys-30 – represents the rate of clot degradation in the 30-minute period following the achievement of maximum clot strength as represented by maximum amplitude.