Interoperator and intraoperator variability of whole blood coagulation assays: a comparison of thromboelastography and rotational thromboelastometry.

Objectives: Near-patient viscoelastic tests have proved useful in decreasing blood and blood product use in cardiac surgery. Two different analyzers are available, TEG and ROTEM. Many different individuals operate these devices, which raises concern that this factor may significantly affect results. The present study sought to objectively assess variability in results between operators.

Design: Prospective study.

Setting: Regional cardiac center.

Participants: Adult patients undergoing elective cardiac surgery.

Interventions: Thirty-six mL of blood were taken from each of 21 patients. TEG kaolin and functional fibrinogen (FF) analyses and the equivalent ROTEM INTEM S and FIBTEM S analyses were performed. Six operators performed one of each test per patient to assess interoperator variability. One further operator performed 6 of each test per patient to assess intraoperator variability.

Measurements And Main Results: All routine measurement parameters were noted and the coefficient of variation (CV) calculated, analyzing comparable parameters. All inter-operator CVs were significantly lower for ROTEM analyses compared with TEG. CV for INTEM S CT/ kaolin r time was 4.7 versus 16.3 and MCF/MA was 2.6 versus 4.3 (p < 0.01). Similarly, FIBTEM S MCF/ FF MA was 8.3 versus 12.2. All intraoperator CVs were significantly lower for ROTEM analyses compared with TEG (p<0.01). CV for INTEM S CT/kaolin r time was 3.1 versus 9.8 and MCF/ MA was 1.6 versus 4. Similarly, FIBTEM S MCF/ MA was 6.9 versus 12.1.

Conclusions: This series of results suggested ROTEM analyses are more reproducible than TEG and, consequently, that ROTEM may be better suited for use in a multiuser environment.