Stability of Non-Activated Rotational Thromboelastometry Assay in Time of Citrated Blood (Appropriate Time Interval for Analysis).

BACKGROUND: Activated methods of thromboelastometry such as EXTEM and INTEM are routinely used in management of severe bleeding. However, sometimes the patient is bleeding despite the normal values of EXTEM/ INTEM. Non-activated thromboelastometry (NATEM) is the most sensitive to coagulopathy and shows pathologic results in such cases. However, it is necessary to find an appropriate time interval between blood sampling and NATEM analysis as the results are strongly influenced by time.

METHODS: In 18 healthy volunteers we performed NATEM analyses of citrated blood samples at 0, 5, 10, 15, 20, 30, and 60 minutes after sampling.

RESULTS: All NATEM parameters showed a procoagulation trend with the time elapsing from blood sample collection with coagulation time (CT) being the most sensitive parameter. After 20 minutes this parameter became relatively stable as the difference among CT at 20th, 30th, and 60th minute was not statistically significant (p > 0.05). The least differences of CT values with maximum time window were found between 30 and 60 minutes.

CONCLUSIONS: Citrated blood sample becomes stable after 20 minutes of storage but the time window between 30 and 60 minutes seems to be more suitable for NATEM analysis in clinical practice.