Predictors of an Increased in Vitro Thrombotic and Bleeding Tendency in Critically Ill Trauma and Non-Trauma Patients

Abstract

Trauma patients are at a high risk of both bleeding and thromboembolism. This study assessed whether conventional coagulation blood tests were reliable predictors of an increased in vitro thrombotic and bleeding tendency of trauma and non-trauma patients. Conventional coagulation blood tests and thromboelastographs of 63 trauma and 63 randomly selected, critically ill non-trauma patients were compared. Increased in vitro thrombotic and bleeding tendencies were defined by a maximum amplitude >72 mm or an angle >74° on the thromboelastograph and a maximum amplitude < 54 mm or an angle <47°, respectively. In vitro thrombotic tendency was more common than bleeding tendency and this was not different between the critically ill trauma and non-trauma patients (59% versus 67% with thrombotic tendency, P=0.461; 11% versus 10% with bleeding tendency, respectively, P=0.999). Thrombocytopenia (<150 × 109 /l) and low fibrinogen concentrations (<2 g/l) were the only two factors associated with an increased in vitro bleeding tendency (both P=0.001) and thrombocytopenia was the only factor associated with a lower risk of in vitro thrombotic tendency (21% versus 75%, P=0.001). Platelet counts (Pearson's correlation coefficient [r]: 0.59, P=0.001) and fibrinogen concentrations (r 0.61, P=0.001) both had a relatively linear association with maximum amplitude of the thromboelastograph. Prolonged International Normalized Ratio (>1.5) and activated Partial Thromboplastin Time (>40 seconds) were, however, not significantly associated with an increased in vitro thrombotic or bleeding tendency. In conclusion, in vitro thrombotic tendency was more common than bleeding tendency in critically ill trauma and non-trauma patients. Platelet counts and fibrinogen concentrations were better predictors of increased in vitro thrombotic and bleeding risks than International Normalized Ratio or activated Partial Thromboplastin Time.

Use of viscoelastic tests to predict clinical thromboembolic events: A systematic review and meta‐analysis

“…Of the 4963 studies identified in the databases, 41 studies from 14 countries, including 10,818 patients in a variety of clinical settings, met the inclusion criteria and were subject to meta‐analysis (Figure ) . A list of the studies excluded and the reasons for their exclusion are summarized in Appendix .…”

Applying the Cell-Based Coagulation Model in the Management of Critical Bleeding

“…The plasma fibrinogen concentration is often the first coagulation factor to reduce to a pathological low level in critical bleeding 63 , and it is also a major determinant of the thickness of the viscoelastic test tracing (e.g. maximal amplitude) 4,8 . In this way, the thickness can be used to guide correction of fibrinogen levels with fibrinogen concentrate or cryoprecipitate if they are used to manage critical bleeding, although laboratory measurement of plasma fibrinogen concentration would be more accurate and specific as the thickness of viscoelastic tracing is also influenced by platelets.…”

Correspondence

“…This pathological feature suggests that patients with thrombotic microangiopathy are intrinsically prothrombotic. If this is the case, it may be possible to use viscoelastic point-of-care devices such as TEG® to confirm the associated hypercoagulability with a reduced r-time or increased maximum amplitude (MA), similar to patients with trauma, sepsis, or heparin-induced thrombocytopenia syndrome [2][3][4] .…”