HPE CSL Managing Perioperative Bleeding handbook | Page 12

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Considering the potentially devastating outcomes of perioperative bleeding , the European Task Force for Advanced Bleeding Care in Trauma and the European Society of Anaesthesiology recommend immediate intervention for patients presenting haemorrhagic shock , and continual evaluation of the coagulation status before , during , and after surgery . 2 , 4 Conventional tests measuring coagulation parameters such as the international normalised ratio ( INR ), activated partial thromboplastin time ( aPTT ) and platelet counts are of very limited value for detecting and predicting the risk of bleeding before surgery or other invasive procedure . Oftentimes , the results are not specific ( for example , INR and aPTT assess the initiation phase of coagulation , making it possible to have a false normal result , whereas platelet counts can only detect platelet dysfunction that is not induced by drugs and not acquired ) or detailed enough , and they can come too late to initiate effective haemostatic control in a timely manner . 7
The implementation of point-of-care ( POC ) devices for coagulation analyses may help identify the often multifactorial causes of bleeding at all phases of perioperative care with only a small volume of whole blood , allowing for the screening of coagulopathies onsite , in the operating room or the intensive care unit . Two types of POC devices are currently available : viscoelastic , for the diagnosis of plasmatic disturbances of haemostasis and fibrinolysis as well as low platelet counts ; and aggregometric , for the identification of platelet dysfunction , either caused by COX-1 inhibitors ( for example , aspirin ) or adenosine diphosphate receptor antagonists , or acquired platelet dysfunctions . Their main disadvantage is the impossibility of identifying coagulopathy caused by hypothermia / hyperthermia or anomalies in pH , calcium ion concentration or haematocrit that affect haemostasis . 7
Viscoelastic methods are based on thromboelastography and measure the time until the start of clotting , the dynamics of clotting , and the stability of blood clots over time . These techniques offer advantages relative to standard laboratory coagulation tests , namely rapid detection of coagulation anomalies resulting from the use of antithrombin agents and prediction of a need for massive blood transfusion , occurrence of thromboembolic events , and mortality in
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