Conventional coagulation assays and rotational thromboelastometry
Traditional coagulation analysis (haemogram, prothrombin time, prothrombin activity, cephalin time, cephalin time ratio, INR and D-dimer and fibrinogen values) as well as SDC-1 levels were performed in whole blood or plasma, as appropriate.
Thromboelastometry, a global coagulation assay describing the dynamics of clot formation and lysis, was performed using ROTEM® sigma with 500 µL of extralesional and intralesional citrated venous blood in accordance with the manufacturer’s protocol. The samples were analysed using cartridges containing the EXTEM/INTEM/FIBTEM/HEPTEM reagents. The minimum test duration was 20 minutes, and the following parameters were recorded: clotting time (CT), the time from test start until a clot firmness amplitude of 2 millimetres is reached; clot formation time (CFT), the time between 2 and 20 millimetres clot firmness amplitude is achieved; clot amplitude at 5 and 10 minutes after CT (A5 and A10) and maximum clot firmness (MCF).
A subsequent study was conducted on 9 paediatric patients and 11 healthy controls with demographic and clinical characteristics similar to those of the initial cohort. The aim of this study was to investigate fibrinolytic clot properties. A modified EXTEM analysis was performed with 360 µL of extralesional citrated venous blood and 125 ng/mL rtPA to accelerate the fibrinolysis process ex vivo, according to the technique described by Kuiper et al. . Values for lysis initiation time (LOT, the time period from clotting time until 15 % of clot lysis is achieved) and lysis time (LT, time from CT until the clot firmness decreases to 10% compared with MCF) parameters were recorded.