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.