Platelets in Critical Illness

Abstract

In patients with critical illness, thrombocytopenia is a frequent laboratory abnormality. However frequent this may occur, a low platelet count is not an epiphenomenon, but a marker with further significance. It is always important to assess the proper cause for thrombocytopenia in critically ill patients because different underlying disorders may precipitate different diagnostic and therapeutic management strategies. Platelets are part of the first-line defense of the body against bleeding; hence, thrombocytopenia may increase the risk of hemorrhage. In case of systemic inflammatory syndromes, such as the response to sepsis, disseminated intravascular platelet activation may occur. This will contribute to microvascular failure and thereby play a role in the development of organ dysfunction. Platelets are circulating blood cells that will normally not interact with the intact vessel wall but that may swiftly respond to endothelial disruption (which is often part of the pathogenesis of critical illness) by adhering to subendothelial structures, followed by interaction with each other, thereby forming a platelet aggregate. The activated platelet (phospholipid) membrane may form a suitable surface on which further coagulation activation may occur. A low platelet count is a strong and independent predictor of an adverse outcome in critically ill patients, thereby facilitating a simple and practically risk assessment in these patients and potentially guiding the use of complex or expensive treatment strategies.

SOFA coagulation score and changes in platelet counts in severe acute kidney injury: Analysis from the randomized evaluation of normal versus augmented level (RENAL) study

“…In addition, our results also highlighted that only significant reductions in platelet counts (>50% reduction) were associated with increased mortality. Finally, although sepsis is a known risk factor for thrombocytopaenia in critically ill patients, our study did not show a significant association between thrombocytopaenia and mortality in septic patients in the ICU setting, which is consistent with current literature …”

“…Thrombocytopaenia is a common complication in patients with AKI, in particular in those requiring RRT, with its incidence ranging from 50 to 65% . Low platelet counts are associated with an increased risk of bleeding, which further contributes to microvascular failure, multiple organ dysfunction as well as high mortality . The Sequential Organ Failure Assessment (SOFA) score was introduced by Vincent et al .…”

Viral hemorrhagic fevers due to endotheliopathy-associated disseminated intravascular microthrombosis and hepatic coagulopathy: pathogenesis based on “two activation theory of the endothelium”

“…An interesting finding is TCIP not only occurs in sepsis/septic shock, but also occurs in other critical illnesses (e.g., severe trauma, complications of surgery, pregnancy and transplant, and immunologic and collagen vascular diseases) [10][11][12][13]. Recently, significant correlation was noted between the degree of thrombocytopenia and severity of the disease, and TCIP influenced the prognosis and likelihood of recovery [14,15]. Severer thrombocytopenia has been associated with systemic inflammatory response syndrome (SIRS) and multi-organ dysfunction syndrome (MODS) [16,17].…”

Pathogenesis of Ebola Viral Haemorrhagic Fever: TTP-like Syndrome Associated with Hepatic Coagulopathy based on "Two Activation Theory of the Endothelium"

“…Recently, significant correlation was noted between the degree of thrombocytopenia and severity of the critical illness as well as prognosis and the likelihood of recovery [10,11]. Severer thrombocytopenia has been associated with systemic inflammatory response syndrome (SIRS) and multi-organ dysfunction syndrome (MODS) [12,13].…”