INTRODUCTION
Bleeding, due to surgical or non-surgical causes, complicates 10% of(1-3) while up to 20-40% of elective procedures
require blood products (4,5). These percentages
increase during urgent/emergency surgery and more complex and
long-lasting procedures bypass (CPB)a technique used in several surgical
settings to obtain an adequate operating fieldrequires a profound
modification of patient’s normal coagulation pattern, eventually leading
to a multifactorial coagulopathy which is associated with an increased
risk of non-surgical bleeding, both in the period immediately following
weaning from CPB and in the first hours / days of hospitalization in the
Intensive Care Unit (ICU) and, consequently, a longer hospital stay and
a poorer long-term outcome. After the publication of the 2017 EACTS /
EACTA guidelines on blood management in adult patients undergoing
cardiac surgery procedures (6), several studies have
addressed the topic of the pathophysiology of CPB-related coagulopathy
and the management of blood products. Nevertheless, to date, there is no
agreement in the literature on the optimal management to be applied in
this specific context. Ternström and colleagues (7)described the coagulation factors activity following coronary artery
bypass surgery and observed an inverse correlation between fibrinogen
levels, platelets, FXIII and postoperative bleeding while no significant
association was observed for other coagulation factors. Both Chandler
and Ranucci (8,9) described the key role of
haemodilution in reducing platelets, fibrinogen, and coagulation
factors, but also in increasing blood products consumption in both
operating room and ICU. Finally, Gielen and colleagues(10) emphasized the importance of haemodilution and
hyperfibrinolysis in determining CPB coagulopathy. Nowadays, the
coagulation status of the cardiac surgical patient is monitored using
standard laboratory parameters, including prothrombin time (PT),
activated partial thromboplastin time (aPTT), international normalized
ratio (INR), activated clotted time (ACT), fibrinogen concentration, and
platelet count. Although these tests are widely and routinely used, they
involve long turnaround times, a critical limitation in settings where
the patient’s coagulation status can change very quickly. Furthermore,
PT and aPTT are generally described as useful to detect coagulation
deficiencies (11,12) but, although they are normally
used as guide for transfusion, they have been shown to be very poor
predictors of bleeding. Viscoelastic methods are increasingly used in
addition to standard laboratory tests. Conventional viscoelastic
parameters recorded with TEG (Haemoscope Inc, Niles, Illinois) or ROTEM
(Tem International GmbH, Munich, Germany) devices during CPB include
ROTEM clotting time (CT), ROTEM maximum clot firmness (MCF), TEG
reaction time (R), and TEG maximum amplitude (MA). Viscoelastic tests
can be easily run at the point of care, decreasing the time required to
obtain information about patients’ coagulation status. Sharma and
colleagues (13) compared TEG results and conventional
tests in predicting postoperative bleeding, stratifying patients into
two groups ”bleeders” and ”non-bleeders” and TEG parameters were the
only ones found to be able to effectively predictive postoperative
bleeding. Notwithstanding, haemostatic alteration of patients undergoing
cardiac surgery is still unclear and is therefore still subject of
debate. The aim of the present study is to describe, through serial
blood controls, traditional tests and Point Of Care (POC), the
coagulation status of patients undergoing CPB for cardiac surgery and to
identify specific coagulation ‘patterns’.