Thromboelastogram as a screening tool for hypercoagulabilityin traumatic brain injury

Background

The term hypercoagulability has been randomly used to describe the increased risk of pathologic thrombus formation. Traumatic brain injury (TBI) is often complicated by life-threatening thromboembolic events [1]. In the trauma patient the incidence of deep venous thrombosis (DVT) is estimated to be from 20% to 90% and to be 4–22% for pulmonary embolism (PE) [2]. The use of the thrombelastograph (TEG) has proven useful in determining an adult patient's coagulation status by measuring the enzymatic/protein elements of coagulation, platelet function, and fibrinolysis from a whole blood sample [3]. The purpose of this study is to compare the TEG as a screening tool for hypercoagulability against other known parameters.

Materials and methods

A prospective study was conducted at University of Mississippi Medical Center, Jackson, MS, using 30 TBI patients, 22 male and eight female, ranging in age from 18 to 79 years. TEG panels were drawn using either venous or arterial blood at 24 and 96 hours post TBI admission. Thirty replicated measurements were made with a two-channel TEG machine. A total of 13 subjects were considered to be hypercoagulable, eight were emerging hypercoagulable and nine were normal. The fibrinogen level as well as the factor 8 level were measured at the same time.

Results

Intrasample variation as to expected fibrinogen results were estimated by the coefficient of variation for each subject. A random effect analysis of variation (ANOVA) was performed and the coefficient of variation (r) was estimated by measuring the ratio of hypercoagulate to fibrinogen and factor 8. A level of confidence > 0.05 was considered statistically significant. Coefficient of variation was 0.96 for the fibrinogen level and 0.62 for factor 8.

Conclusion

Although the sample size is small, we suggest that the TEG is a useful screening tool for hybercoagulability in TBI and hence careful monitoring for DVT and PE.