An audit of the diagnostic accuracy of rotational thromboelastometry for the identification of hypofibrinogenaemia and thrombocytopenia during cardiopulmonary bypass

摘要

We audited the diagnostic accuracy of ROTEM (R) (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) mm, and 35 mm respectively. We also calculated the accuracy of smaller thresholds and earlier indices. We found that FIBTEM A10 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.