We audited the diagnostic accuracy of ROTEM® (TEM Innovations, GmbH, Munich, Germany) measurements of hypofibrinogenaemia (fibrinogen <1.5 g/l) and thrombocytopenia (platelet count <100 x 10 9 /l) in 200 adult non-transplant patients during cardiopulmonary bypass (CPB). Blood samples were obtained for FIBTEM (assay for the fibrin part of the clot), PLTEM (calculated platelet-specific component), and laboratory measurements simultaneously. Our thresholds for FIBTEM and PLTEM were A10 (clot firmness 10 minutes after clotting time) ≤8 mm, and <35 mm respectively. We also calculated the accuracy of smaller thresholds and earlier indices. We found that FIBTEM A10 ≤8 mm had low sensitivity (0.62) for hypofibrinogenaemia. With the 13% hypofibrinogenaemia prevalence in our sample, the positive predictive value (PPV) was 0.47. In contrast, FIBTEM A10 ≤8 mm had higher specificity (0.90) (negative predictive value [NPV] 0.94). Of the other FIBTEM values analysed, only A5 ≤6 mm had similar or superior accuracy. The PLTEM results were less encouraging (sensitivity 0.81, specificity 0.62). With our prevalence of thrombocytopenia (also 13%), the PPV was only 0.24. However, the NPV was high (0.96). Of the other PLTEM values analysed, only A5 <25 mm had similar or superior accuracy. These findings indicate that during CPB FIBTEM A10 ≤8 mm and PLTEM A10 <35 mm have greater accuracy in identifying the absence of hypofibrinogenaemia and thrombocytopenia respectively than their presence. On the basis of these results we would be reassured by FIBTEM A10 values >8 mm and PLTEM A10 values ≥35 mm, but would continue to use laboratory measurements for confirmation. We would not use FIBTEM A10 ≤8 mm or PLTEM A10 <35 mm values alone to guide replacement therapy unless clinical conditions warranted an immediate decision before laboratory measurements were available.

The ROTEM®delta (TEM Innovations GmbH, Munich, Germany) has been used extensively worldwide for the assessment of coagulation in cardiac surgical patients. Recently, a new cartridge-based ROTEM device (ROTEM®sigma, TEM Innovations GmbH, Munich, Germany) has become available. In this paper we report an audit of the diagnostic accuracy of the ROTEM sigma for the identification of hypofibrinogenaemia in cardiac surgical patients. We hypothesised that the diagnostic accuracy of the ROTEMsigma for the identification of hypofibrinogenaemia would be in a similar range to that previously reported for the ROTEMdelta. Simultaneous blood samples for Clauss laboratory fibrinogen and ROTEMsigma FIBTEM measurements were obtained immediately after heparin reversal post-cardiopulmonary bypass in 200 adult cardiac surgical patients. The sensitivity, specificity, and positive and negative predictive values for FIBTEM A5 and A10 for the identification of hypofibrinogenaemia (Clauss fibrinogen <1.5 g/l) were calculated. The prevalence of hypofibrinogenaemia across the 200 patients was 8%. The mean sensitivity and specificity of FIBTEM A10 ≤8 mm for the identification of hypofibrinogenaemia were 0.75 and 0.90 respectively, which are in a similar range to that reported in several previous studies using the ROTEMdelta. For FIBTEM A5 ≤6 mm the values were 0.63 and 0.98 respectively. The predictive values were also in a similar range to those previously reported for the ROTEMdelta, with low false negative rates (2% for A10 ≤8 mm; 3% for A5 ≤6 mm). These findings support the use of the ROTEMsigma as an alternative to the ROTEMdelta for the identification of hypofibrinogenaemia post-cardiopulmonary bypass in cardiac surgical patients. However, further studies are required in other settings.

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