Temporal changes in ROTEM®-measured coagulability of citrated blood samples from coagulopathic trauma patients

BackgroundRotational thromboelastometry (ROTEM®) relies on citrated blood samples, which are regarded as biologically stable for up to 4 h after venepuncture. However, this recommendation is based on data from normal volunteers. The aim of this study was to evaluate possible temporal changes in the coagulability of blood samples from coagulopathic trauma patients.Patients and methodsThis is a prospective series of 10 coagulopathic (maximum clot firmness, MCF < 40 mm) trauma patients. ROTEM® EXTEM (tissue factor activated) and FIBTEM (tissue factor activated, cytochalasin D inhibited) analyses were performed on samples obtained on admission, and after approximately 60 min of storage in an incubator, at 37 °C.ResultsThere were statistically significant differences between the median EXTEM MCF (22 mm vs 54 mm, p < 0.001) and α angle (30.5 vs 59.5°, p = 0.004) of the analyses performed immediately after sampling, and 51 min (median) subsequently, but not coagulation time (CT, p = 0.133), clot formation time (p = 0.0625) or maximum lysis (ML, p = 0.154). There were also no differences in median FIBTEM MCF (p = 1.00) or CT (p = 0.877) between the immediate and delayed analyses.ConclusionsRepeated ROTEM® EXTEM analysis of citrated samples from coagulopathic trauma patients shows a spontaneous improvement in coagulability with time. The absence of parallel changes on FIBTEM analysis suggests that this effect may be due to a change in platelet function.