OC 33.4 - Platelet contribution to clot strength in thromboelastometry in preterm septic neonates reflects better platlet count than platelet function.

Background: The difference in amplitude between the EXTEM and the FIBTEM thromboelastometry (ROTEM) assays is considered an index of platelet contribution to clot strength (MCFplatelet) guiding treatment in thrombocytopenic patients. However, recent literature challenges the validity of MCFplatelet suggesting that the difference in maximum clot elasticity (MCEplatelet) is highly accurate. The overall research lacks enough data to elucidate the implementation of such modalities in sick neonates.

Aims: Investigate MCFplatelet and MCEplatelet in reflecting platelet count and function by using ROTEM and platelet flow cytometry.

Methods: Twenty eight preterm septic neonates of 24 to 34 gestational weeks compared to 30 healthy counterparts. Coagulation was assessed by ROTEM and platelet function by flow cytometry. The study was conducted at 3-time points during sepsis and at 1-time point for controls.

Results: MCFplatelet and MCEplatelet were tested for association with platelet count and function in a total of 112 tests. MCFplatelet in patients showed a low (R2 =18.79%) association with platelet count and function (GPIb receptors, R2=11.44% and TRAPtest, R2=12.69%) and was negatively correlated with GPIb inactive and active receptors (r=-0.32,p=0.0035). MCFplatelet in controls was negatively correlated with P-selectin inactive receptors (r=- 0.5, p 0.004). MCEplatelet showed higher association (R2 =47.66%) with platelet count and had better discrimination capability (AUC 0.8164) than MCFplatelet (AUC 0.7889) in platelet count < 100 x 103/l. No association was found between MCEplatelet, GP receptors and TRAPtest.

Conclusion(s): MCEplatelet predicts better platelet count than MCFplatelet, however fails to precisely reflect platelet function. Platelet function is poorly related to MCFplatelet. In clinical practice, the difference in elasticity may replace the difference in amplitude for platelet count but further research and new diagnostic modalities should be performed to discriminate the contribution of platelet function to clot strength.