Thrombocytopenia in the Intensive Care Unit—Diagnostic Approach and Management
Section snippets
Definition of Thrombocytopenia
Thrombocytopenia is commonly defined as a platelet count <150 × 109/L.1 Some authors apply a cut off of 100 × 109/L for ICU patients7 and others further specify platelet counts <50 × 109/L as severe thrombocytopenia.8 Absolute platelet counts alone are not sufficient to characterize thrombocytopenia in critically ill patients; also, the time course of platelet counts provides important information. For example, a platelet count decline of >50% compared to the baseline value can be normal after
Etiology of Thrombocytopenia
Five major mechanisms can result in thrombocytopenia (Table 1). ICU patients commonly develop thrombocytopenia as a result of (1) hemodilution and/or (2) increased platelet consumption due to massive tissue trauma, bleeding, sepsis, or disseminated intravascular coagulation (DIC), and extracorporeal circuits. Less common are (3) decreased platelet production, (4) increased platelet sequestration, and (5) platelet destruction by immune mechanisms.
Importantly, the in vitro artifact of
Platelet Count Course in Different ICU Patient Populations
The dynamics of the platelet count decrease varies between different patient populations. Therefore, the evaluation of a normal, rather “physiologic” platelet count course needs to be specified in the setting of major surgery, trauma, in patients undergoing minor surgery or medical patients. Typical platelet count courses in patients with different underlying morbidities measured at our institution within prospective studies are displayed in Figure 1.
Pathologic Platelet Count Course and Prognosis in ICU Patients
Several clinical studies demonstrated higher morbidity and mortality if the platelet count recovery is delayed beyond day 4.15, 16, 24, 25, 26 For example, the mortality rate in ICU patients with persistent thrombocytopenia at day 14 was 66%24 compared to 16% in patients with normal or increased platelet counts at this stage. Furthermore, 30-day mortality of post-cardiac surgery patients was 1.3% in those with a recovery of platelet counts >100 × 109/L after day 4 and 12% in patients with
Diagnostic Approach of Thrombocytopenia in Critically Ill Patients
Deviations from the “physiologic” platelet course in severely ill patients, as described above, can be used for diagnostic purposes. Based on the patient population and the onset of thrombocytopenia, specific causes of thrombocytopenia become likely (Table 1).
At ICU admission, postsurgical and trauma patients presenting with thrombocytopenia often have a coagulopathy caused by major blood loss, hemodilution, and/or massive tissue trauma. The severity of thrombocytopenia after surgery or trauma
Therapeutic Platelet Transfusion in the Bleeding Patient
Thrombocytopenia is a risk factor for bleeding, and bleeding symptoms in thrombocytopenic patients are an established trigger for therapeutic platelet transfusions.27 There is no fixed platelet count threshold defined in ICU patients to which the platelet count should rise after transfusion. Based on expert opinion, several guidelines recommend to maintain platelet counts >100 × 109/L in massive bleeding27, 28 or if bleeding occurs at dangerous sites, eg, intracranial hemorrhage.
The bleeding
Trauma
Trauma coagulopathy consists of hemodilution, acidosis, hypothermia, loss and consumption of clotting factors and platelets, and hyperfibrinolysis, which all need concomitant therapy. In massively transfused patients, red blood cell concentrates and plasma alone are not able to restore coagulation. While the optimal ratio between red blood cell concentrates, platelet concentrates, and fresh frozen plasma is highly controversial, a recent study controlling for survival bias suggests a survival
Conclusion
Thrombocytopenia is common in ICU patients during the first 4 days and is correlated with the severity of the underlying illness or tissue damage. A poor prognosis is indicated by platelet counts that do not recover or show a progressive decrease 5 days after admission. The most common causes for a low platelet count in ICU patients are sepsis, massive tissue trauma, and DIC. Treatment should target the underlying disease. In most circumstances, the risk of bleeding associated with
References (80)
- et al.
The frequency and clinical significance of thrombocytopenia complicating critical illness: a systematic review
Chest
(2011) - et al.
Thrombocytopenia in medical-surgical critically ill patients: prevalence, incidence, and risk factors
J Crit Care
(2005) Critical issues in hematology: anemia, thrombocytopenia, coagulopathy, and blood product transfusions in critically ill patients
Clin Chest Med
(2003)- et al.
Coagulopathy in critically ill patients: part 1: platelet disorders
Chest
(2009) - et al.
The 4Ts scoring system for heparin-induced thrombocytopenia in medical-surgical intensive care unit patients
J Crit Care
(2010) - et al.
Occurrence and clinical significance of pseudothrombocytopenia during abciximab therapy
J Am Coll Cardiol
(2000) - et al.
Early-onset and persisting thrombocytopenia in post-cardiac surgery patients is rarely due to heparin-induced thrombocytopenia, even when antibody tests are positive
J Thromb Haemost
(2010) - et al.
The severity of trauma determines the immune response to PF4/heparin and the frequency of heparin-induced thrombocytopenia
Blood
(2010) - et al.
Early coagulopathy in trauma patients: an on-scene and hospital admission study
Injury
(2012) - et al.
Thrombocytopenia and outcome in critically ill patients with bloodstream infection
Heart Lung
(2010)
Platelet count decline: an early prognostic marker in critically ill patients with prolonged ICU stays
Chest
Management of massive blood loss: a template guideline
Br J Anaesth
Transfusion-related mortality: the ongoing risks of allogeneic blood transfusion and the available strategies for their prevention
Blood
Prevalence, incidence, and risk factors for venous thromboembolism in medical-surgical intensive care unit patients
J Crit Care
Therapeutic platelet transfusion versus routine prophylactic transfusion in patients with haematological malignancies: an open-label, multicentre, randomised study
Lancet
Reversal of the anti-platelet effects of aspirin and clopidogrel
J Thromb Haemost
Platelet transfusion for reversal of dual antiplatelet therapy in patients requiring urgent surgery: a pilot study
J Thromb Haemost
Thrombocytopenia associated with chronic liver disease
J Hepatol
Von Willebrand factor, ADAMTS13, and thrombotic thrombocytopenic purpura
Blood
Treatment of severe neurological deficits with IgG depletion through immunoadsorption in patients with Escherichia coli O104:H4-associated haemolytic uraemic syndrome: a prospective trial
Lancet
Management of refractory cases of catastrophic antiphospholipid syndrome
Autoimmun Rev
A systematic evaluation of laboratory testing for drug-induced immune thrombocytopenia
J Thromb Haemost
Clinical and biological features of patients suspected or confirmed to have heparin-induced thrombocytopenia in a cardiothoracic surgical ICU
Chest
Evaluation of pretest clinical score (4 T's) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings
J Thromb Haemost
Predictive value of the 4Ts scoring system for heparin-induced thrombocytopenia: a systematic review and meta-analysis
Blood
The HIT Expert Probability (HEP) score: a novel pre-test probability model for heparin-induced thrombocytopenia based on broad expert opinion
J Thromb Haemost
Prospective evaluation of PF4/heparin immunoassays for the diagnosis of heparin-induced thrombocytopenia
J Thromb Haemost
Heparin-induced thrombocytopenia in patients requiring prolonged intensive care unit treatment after cardiopulmonary bypass
J Thromb Haemost
Thrombocytopenia and prognosis in intensive care
Crit Care Med
Thrombocytopenia in patients in the medical intensive care unit: bleeding prevalence, transfusion requirements, and outcome
Crit Care Med
Intensive Care Study of Coagulopathy Investigators. Thrombocytopenia and platelet transfusion in UK critical care: a multicenter observational study
Transfusion
Diagnosis from the blood smear
N Engl J Med
EDTA-dependent pseudothrombocytopenia: further insights and recommendations for prevention of a clinically threatening artifact
Clin Chem Lab Med
Heparin-induced thrombocytopenia in patients treated with low-molecular-weight heparin or unfractionated heparin
N Engl J Med
Antibodies to platelet factor 4-heparin after cardiopulmonary bypass in patients anticoagulated with unfractionated heparin or a low-molecular-weight heparin: clinical implications for heparin-induced thrombocytopenia
Circulation
Blunted rise in platelet count in critically ill patients is associated with worse outcome
Crit Care Med
Determinants of platelet number and regulation of thrombopoiesis
Hematology Am Soc Hematol Educ Program
Pharmacodynamics and pharmacokinetics of AMG 531, a novel thrombopoietin receptor ligand
Clin Pharmacol Ther
The clinical significance of platelet counts in the first 24 hours after severe injury
Transfusion
Cited by (42)
Xanthotoxin, a novel inducer of platelet formation, promotes thrombocytopoiesis via IL-1R1 and MEK/ERK signaling
2023, Biomedicine and PharmacotherapyDiagnostic predictors in thrombocytopenia in Intensive Care. A systematic review of the literature
2022, Acta Colombiana de Cuidado IntensivoEpidemiology of disseminated intravascular coagulation in sepsis and validation of scoring systems
2019, Journal of Critical CareCitation Excerpt :The reason why our findings are in contradiction with other previous studies might be that most of the previous studies did not include general severity scores in their multivariable analysis, except one small retrospective study [21]. Thrombocytopenia in patients with severe sepsis are not only caused by DIC but also by various conditions [22]. Many patients with severe thrombocytopenia and sepsis do not fulfill the criteria for overt DIC [23].
Heparin-Induced Thrombocytopenia in the Critically Ill Patient
2018, ChestCitation Excerpt :However, thrombocytopenia alone does not differentiate HIT from other, possibly equally concerning, causes of thrombocytopenia in patients in the ICU. Twenty percent to 25% of medical patients who are critically ill and 35% to 41% of patients who have undergone surgery or trauma will have thrombocytopenia (platelet counts < 100 × 109/L).38-40 In PROTECT, the incidences of mild (100 × 109/L to 149 × 109/L), moderate (50 × 109/L to 99 × 109/L), and severe (< 50 × 109/L) thrombocytopenia were 15.3%, 5.1%, and 1.6%, respectively.41
Conflict of Interest: The authors have no conflict of interest to declare.