Coagulopathy and Platelet Disorders in Critically Ill Patients

Abstract

Coagulation abnormalities occur frequently in critically ill patients and may have a major impact on clinical outcome. An adequate explanation of physiology of coagulation system is important to maintain the integrity of a closed, high-pressure circulatory system when vascular damage occurs; it is a critical event in the arterial diseases associated with cerebrovascular stroke, and venous thromboembolic disorders. Normally, only at the site of an injury will the fluidity of the blood be altered and a blood clot formed by a complex interaction of many elements (the endothelium, the platelets, and coagulation factors). With vasospasm, activation of platelets at the site of vascular injury to form a platelet plug constitutes the primary response to hemostasis. The coagulation cascade, is a series of enzymatic reactions involving the sequential activation of a number of circulating plasma proteins called the coagulation factors which involved in the extrinsic pathway and the intrinsic pathway constitutes the secondary hemostasis with the ultimate goals of stemming the loss of blood at the site of an injury and laying the groundwork for injury repair and healing. Coagulation disorders are common among critical care patients and may range from isolated thrombocytopenia or prolonged global clotting tests to complex defects, such as disseminated intravascular coagulation. Platelet disorders lead to defects in primary hemostasis via prolonged bleeding time, and characterized by petechiae and purpura. In comparison, coagulation factors deficiencies lead to defects in secondary hemostasis result in delayed deep bleeding and characterized by hemarthrosis. Older patients are often nutritionally or immunologically impaired, making them an easy target for infection and coagulation disorders. Other risk factors for coagulopathy are D.M, malignancy, surgical / invasive procedures, use of cytotoxic and immunosuppressant agents. A medical history taking, drug history, physical examination and laboratory investigations as CBC with full coagulation profile such as; bleeding time, clotting time, P.T, a.P.T.T and FDPs are important for any patient with thrombocytopenia or coagulation disorders in ICU. An adequate explanation for the cause of the coagulation abnormality is important because many underlying disorders may require specific treatment. Causes of thrombocytopenia related to increased destruction include immune thrombocytopenia (eg, autoimmune, alloimmune, drug-induced, HIT) and increased consumption (eg, sepsis, DIC, TTP). Causes of thrombocytopenia related to decreased production include bone marrow depression. Treatment of coagulation abnormalities should be directed at the underlying condition, but supportive therapy may be required. Deficiencies in platelets and coagulation factors in bleeding patients or patients at risk for bleeding can be achieved by transfusion of platelet concentrate or plasma products, respectively. In addition, prohemostatic treatment may be beneficial in case of severe bleeding as prothrombin complex concentrate, factor XIII, and fibrinogen whereas restoring physiological anticoagulant pathways may be helpful in patients with sepsis and DIC. Supportive treatment of the coagulopathy associated