Bleeding risk assessment in elective cardiac surgery

Petricevic et al. compared platelet function during elective cardiac surgery using ROTEM platelet and Multiplate impedance aggregometry 1. The authors measured platelet function at three time points; before induction of anaesthesia; after removal of the aortic clamp; and 5–10 min after protamine sulphate administration, which allowed measurement of platelet haemostatic function in case of bleeding and precise timing and dosing of antiplatelet therapy. Could I invite the authors to publish details of the whole blood counts, particularly haemoglobin concentration and platelet count at each time point, as interpreting the results of impedance aggregrometry depends greatly on these variables 2-4? Can the authors also confirm that the recommended resting time of 30 min was observed between blood drawing and processing? Could the authors provide details of the type and volume of fluid administered perio-peratively, and the dose of heparin and protamine sulphate administered, as these can also affect platelet function tests 5, 6? Also, was a power analysis performed? Finally, I disagree with the authors that this study confirms the superiority of platelet function analysis over a meticulous drug history. The authors presented data on the use of single and double platelet inhibitors, but not on specific drug and bleeding history, and did not undertake any statistical analysis correlating test results and drug history. Instead, patients were clustered according to their drug use and blood products received (according to their Fig. 3). Could I invite the authors to comment on this point?