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Disseminated Intravascular Coagulation Hematologist’s Perspective

Dr. Naghmi Asif and Prof. Khalid Hassan

MCH Centre, Pakistan Institute of Medical Sciences, Islamabad

Introduction

Disseminated intravascular coagulation (also called consumption coagulopathy and defibrination syndrome) is an acquired condition characterized largely by uncontrolled activation of the coagulation system, excess thrombin generation, which results in the intravascular formation of fibrin and ultimately thrombotic occlusion of small and midsize vessels. 1, 2 There is also activation of the fibrinolytic system, and this along with consumption of coagulation factors and platelets results in bleeding, particularly when the patient’s blood vessels have been damaged by vascular punctures, trauma, or surgery. There is thus evidence of both thrombin and plasmin activation. Intravascular coagulation can also compromise the blood supply to organs leading to hemodynamic and metabolic derangements and multiple organs failure resulting in increased mortality and morbidity.3 Sometimes thrombosis and hemorrhage may occur almost at the same time and clinical features are characterized by the variable presence of both intravascular coagulation and hemorrhage. Etiological factors (Table 1)

DIC begins with appearance of procoagulant activity in dynamic or active circulation. It is however not a primary disease but reflects a complication of one of several possible underlying illnesses or conditions4 and sometimes the features of primary disease are overtaken by sudden onset of life threatening hemorrhage or hypoperfusion of vital organs due to microcirculatory obstruction.5 It has been proved in various studies that most prevalent etiological factors include infections, obstetric complications and malignancies.6 Pathophysiology

The diagnosis of disseminated intravascular coagulation is made by laboratory testing. In order to understand the use of screening and specific tests for this entity, a brief review of these laboratory tests is needed. Disseminated intravascular coagulation is mainly due to the presence of thrombin in the systemic circulation. Thrombin is generated from prothrombin by activation of either the intrinsic and/or extrinsic coagulation systems. Effects of Thrombin Thrombin plays a key role in coagulation system. Increased thrombin generation is predominantly mediated by tissue factor, which enters the circulation as a result of tissue damage or enhanced expression of tissue factor on cells in response to endotoxins or cytokines.7,8 Thrombin itself is

very short lived and difficult to measure. Thus, the effects of thrombin on the circulating blood are usually used to

Table 1: Etiological Factors associated with DIC

Infections (Herpes, Rubella, Smallpox, Acute hepatitis, Viral

hemorrhagic fever) (Septicemia particularly due to gram negative organisms,

Meningococcemia etc) Rickettsial (Rocky mountain spotted fever, others) Mycotic (Aspergillosis, Histoplasmosis) Protozoal (Malaria, Kala-azar, Typanosomiasis) Obstetrical Complications Abruptio placenta Septic abortion Amniotic fluid embolism Intrauterine fetal death Abortions Degenerating hydatidiform mole Abdominal pregnancy Neoplasms Carcinomas (Prostate, Pancreas, Ovary, Breast, lung, etc) Miscellaneous (metastatic carcinoid, Rhabdomyosarcoma, Neuroblastoma, others) Disorders of Hemopoietic System Acute Leukemias (Promyelocytic, other types)

Intravascular hemolysis (transfusion reaction, PNH, drug induced, Sickle cell disease) Histiocytic Medullary Reticulosis Vascular Disorders Malformations (Giant hemangiomas, aneurysms, others) Collagen vascular disorders Hypoxia and hypoperfusion Congestive failure with pulmonary emboli, Myocardial infarction, shock, hypothermia Massive tissue injury Large traumatic injuries and burns, extensive surgical intervention, fat embolism Miscellaneous Snake bite, anaphylaxis, heat stroke, diabetic acidosis, acute pancreatitis, graft versus host disease. detect its presence. Thrombin is a known activator of the fibrinolytic system. Thrombin also acts on fibrinogen in a very specific way to release two peptides (fibrino-peptides

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A and B) producing a fibrinogen molecule that is still soluble in plasma called soluble fibrin monomer (sFM). Fibrin monomer then polymerizes and is converted to the insoluble fibrin form by the action of activated factor XIII. Factor XIII is similarly activated by thrombin. Thrombin also acts on platelets to induce aggregation and subsequent thrombocytopenia occurs. Thrombin in small amounts acts on both the intrinsic and extrinsic coagulation systems by facilitating increased production of factor V and VIII. Fibrinolysis

Fibrinolysis is a process in which plasmin, an active form of plasminogen, cleaves fibrin and fibrinogen to restore vessel patency following hemostasis. The formation of plasmin (fibrinolysin) is a very necessary part of the normal physiologic response to thrombin generation. Activity of plasmin is regulated by vascular endothelial cells that secrete both serine protease plasminogen activators and plasminogen activator inhibitors (PAI-1 and PAI-2). It is suppressed at the time of maximal activation of coagulation due to a sustained rise in plasminogen activator inhibitor-1. Plasmin may degrade fibrin polymer, fibrin monomer, and fibrinogen. All four of these reactions result in the formation of what are called fibrinolytic split or degradation products (FSP, FDP). Inhibitors of coagulation

Despite potent stimulation of the coagulation pathway, it cannot be propagated unless there is a problem with the natural anticoagulation pathways.9 These pathways include antithrombin III, protein C, protein S and tissue factor pathway inhibitor (TFPI). These inhibitors of coagulation are also very important for development of DIC particularly in sepsis which leads to suppression of this system. Activation protein C is induced by a complex formed thrombin and endothelial cell protein called Thrombomodulin. Activated protein C causes inhibition of factor V and factor VIII. Activity of this factor is also greatly enhanced by Protein S (free protein S)10 Tumor necrosis factor (TNF) downregulates thrombomoduhn expression on endothelial cells, resulting in a decreased protein C activity, thus further contributing to a procoagulant state.11,12

Antithrombin III is a circulating plasma protease inhibitor that neutralizes mainly thrombin and factor Xa. Plasma levels of antithrombin III, the most important inhibitor of thrombin, are markedly reduced during DIC due to a combination of consumption, degradation by elastase from activated neutrophils, and impaired synthesis.13 Tissue factor pathway inhibitor directly inhibits factor Xa, and it complexes with factor Xa to inhibit tissue factor. Its increase in DIC is insufficient in relation to the increase in tissue factor–dependent activation of coagulation.

Thus Pathophysiology of DIC is complex. The mechanisms that activate or trigger DIC act on processes that are involved in normal Hemostasis. These mechanisms have in common the capacity in terms of either the

magnitude or the duration of activating stimulus, to exceed normal compensatory processes. Thrombin is persistently generated and fibrin is formed in the circulating blood. Fibrinogen, various coagulation factors and platelets are consumed. The fibrinolytic mechanism is activated and large amounts of FDPs are produced, which further impair the haemostatic function. Normal compensatory processes become impaired creating a self- perpetuating “viscous cycle”. The 3 major mechanisms underlying DIC are:

1. Excessive generation and circulation of thrombin, 2. Impairment of the natural anticoagulant pathway, and 3. Suppression of fibrinolysis.

Bleeding, shock and vascular occlusion commonly supervene and produce profound alteration in the function of various organ systems. The ultimate outcome depends upon equilibrium between the various pathologic processes and compensatory mechanisms. Hence coagulopathy may be compensated or decompensated depending upon the degree of consumption of the various procoagulants and platelets. If the consumption of these procoagulants exceeds production, then the resultant levels may be reduced and many cases may be reduced below normal hemostatic levels. In such cases, one would see a decompensated form of DIC which, by and large, is the predominant variety.14

Conditions that may be complicated by disseminated intravascular coagulation (DIC) include: Infectious Disease

In septic patients, DIC occurs frequently, may complicate the already complex clinical situation and contribute to the high mortality. Recent clinical trials for severe sepsis showed that the mortality in severe sepsis was about 35–45%15,16 and it was higher in those that experience DIC than in those without.17 Although virtually all microorganisms can cause disseminated intravascular coagulation including viruses and parasites, bacterial infection is most frequently related to the development of this syndrome. Among these bacterial infections gram-negative bacterial sepsis is the most notable infectious cause, but DIC may occur with any cause of sepsis. Clinically overt disseminated intravascular coagulation may occur in 30-50% of patients with gram-negative sepsis18

The mechanisms involved in the onset of DIC associated with sepsis are different from that associated with leukemias/solid cancers. Triggers of the activation of diffuse coagulation in patients with infections include cell-specific membrane components of the microorganism, such as lipopolysaccharide or endotoxin, or bacterial exotoxins leading to activation of the cytokine network and increased plasma levels of elastase, and C reactive protein (CRP). Other mechanisms include the release of fat and phospholipids from tissue into the circulation, hemolysis, and endothelial damage, all promoting the systemic activation of coagulation. Tissue factor activity in peripheral blood is markedly elevated upon tissue injury

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and activation of monocytes and is the main factor responsible for coagulopathy in patients with polytrauma and patients with sepsis. Other factors responsible for the development of DIC in septicaemia are: suppression of protein C-protein S system and an increase in fibrinolytic activity. TNF- is supposed to be a mediator of this effect. Coagulopathy is present in 25% of trauma patients and is associated with a five-fold increase in mortality.7 Its presence may be confused with coagulopathy secondary to massive blood transfusion. DIC is a rare complication following severe burn trauma. It complicates the course of the critically ill burn patient, although appropriate therapy prevents its fulminant course.19 Cancer

Both solid tumors and hematologic cancers may be complicated by disseminated intravascular coagulation. 10- 15 % of patients with metastasized tumors have evidence of disseminated intravascular coagulation, and the condition is present in approximately 15 percent of patients with acute leukemia.20,21 The mechanism of the derangement of the coagulation system in patients with cancer is not clear. Expression of tissue factor by cancer cells (which in conjunction with factors VII–IX, can activate the intrinsic pathway)22 is thought to play an important role in the pathogenesis of DIC in patients with malignancy.23,24 Other factors include release thromboplastin and other attractant factors from the tumor tissue, with subsequent clot formation. In one of the studies done by Malik Zeb et al at D.I. Khan on patients of breast carcinoma found that levels of fibrinogen degradation products (FDPs) and D-Dimers were quite high in breast carcinoma, especially in those with distant metastasis.25

A distinct form of disseminated intravascular coagulation is frequently encountered in patients with acute promyelocytic leukemia, which is characterized by a severe hyperfibrinolytic state in addition to an activated coagulation system (by increased expression of tissue factor). This hyperfibrinolysis is due to increased expression of Annexin II expression by blast cells which act as co receptor for plasminogen activator and plasminogen. In one of the studies done by Hideki Uchiumi it was found that Leukocyte counts, C-reactive protein, and lactate dehydrogenase were significantly higher in patients of APL with DIC.26 Though DIC is most frequently associated with AML-M3 it can also be seen in other hematological malignancies as well. In a study done by Rizwan Qazi et al on patients of AML they found that DIC was the most frequent in AML M3 (69 %) followed by in M5 (40 %), M2 (23.1 %), M4 (18.2 %) and M1 (16.6 %), respectively. Another study was done in Japan to look for prevalence and clinical characteristics on de novo non–APL AML, they observed that DIC was diagnosed in 32% of their patients and its incidence was the highest in M5 (60%) and lowest in M6 (0%). They also mentioned that DIC also has association with high leukocyte count and raised CRP levels

(observed both in infections and malignancies).27 Similarly Anwar M et al observed deranged

coagulation profile with raised FDPs in 15% their ALL patients.37 DIC is thus still a devastating complication of acute leukemias and early therapeutic intervention for DIC is warranted. Therefore, efforts to identify the clinical parameters associated with DIC are important.28 In a study done by Kohji Okamoto et al on Frequency and hemostatic abnormalities in pre-DIC patients, it was found that the highest absolute number of DIC cases was observed in patients with infectious disease, solid cancer and hematopoietic disorders.29 Obstetrical Disorders

DIC is a classic complication of obstetrical conditions which include obstetric accidents as amniotic fluid embolism, placental abruptio, placenta previa, pre-eclampsia, eclampsia, HELLP) syndrome (Hemolysis, elevated liver enzymes, and low platelet count), retained fetus syndrome, retained products of conception and abortion occurring in more than 50 % of patients with these conditions.30 It can also be associated with gynecologic malignancies e.g. ovarian cancer, uterine cancer, breast cancer and paraneoplastic syndromes.

Amniotic fluid embolism (AFE) is a rare catastrophic complication of pregnancy; the estimated incidence is 1 in 8000 to 1 in 80 000 pregnancies.31 AFE is associated with a mortality rate of 60% to 86 %.32,33 DIC is one of the common potential complications of this condition, probably because of the presence of direct factor X–activating factor and thromboplastin like material (or tissue factor), which is a potent activator of coagulation in vitro. AFE remains one of the most devastating complications of pregnancy. The diagnosis is difficult to make because it is mostly a diagnosis of exclusion.

Similarly abruptio placentae is another condition which may end up in DIC and the degree of placental separation correlates with the extent of disseminated intravascular coagulation.34 Although these obstetrical conditions may cause fulminant disseminated intravascular coagulation sometimes they are short-lived and self-limiting. Management is essentially supportive. The administration of heparin is generally limited to patients with chronic compensated DIC who have predominantly thrombotic manifestations

Preeclampsia can also be complicated by disseminated intravascular coagulation, which occurred in 7 % of consecutive patients with severe preeclampsia in one study.35 Similarly another study was done by Tayyab M. et al in PGMI Lahore on patients of pre-eclampsia. They found that although various baseline tests like PT, APTT were normal in these patients FDPs and D-Dimers were raised in majority of patients with pre-eclamsia, especially those with severe pre-eclampsia. They also mentioned that D-Dimers were more sensitive as compared to FDPs for evaluation of these patients.36 In another study done by

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Asifa Ghazi et al in Civil Hospital Karachi the frequency of deranged coagulation profile among obstetric patients was 4.3%, and among them 84% had raised FDPs. However they did not mentioned frequency of DIC their patients.37

Likewise HELLP syndrome is an atypical form of severe preeclampsia, and if not treated is potentially fatal for both mother and fetus. Mostly presentation of HELLP syndrome is after 34 weeks of gestation but presentation may be between 20 weeks of gestation to few days after delivery. It is estimated that up to 10% of pregnancies are affected by HELLP syndrome.38 HELLP Syndrome is also associated with quite a number of cases of disseminated intravascular coagulation. In one of the prospective studies done by BM Sibai, on 442 pregnancies with HELLP syndrome DIC was observed in 21% patients.39 Giant Hemangiomas

Giant hemangiomas (the Kasabach–Merritt syndrome) and even large aortic aneurysms may result in local activation of coagulation.40,41 In patients with these conditions there is local activation of coagulation factors can reach the systemic circulation and cause disseminated intravascular coagulation resulting in the systemic depletion of locally consumed coagulation factors and platelets. Clinical features

DIC also called consumption coagulopathy and defibrination syndrome is a complication of underlying illness occurring in approximately 1% of hospital admissions.42 Factors which influence the clinical course of DIC include potency of the procoagulant agent and its dose, the speed with which this enters the body, presence of coexisting endothelial damage, vasomotor changes (e.g. DIC due to endotoxin shock) and efficiency of compensatory mechanisms. There are 2 clinical forms of DIC: 1.Acute DIC

Acute DIC occurs when a large amount of procoagulant enters the circulation over a brief period of time, overwhelming the body’s ability to replenish coagulation factors and predisposing patients to bleeding. This presents with life-threatening bleeding from various sites, often in a patient who is already seriously ill. Shock and multiple organ failure frequently coexist, making therapeutic decisions difficult. It can exist in the compensated and uncompensated forms: Compensated DIC

When the stimulus for coagulation is mild, the liver can increase production of clotting factors to up to 5 times the normal rate, 'in an effort to maintain plasma levels.43 Similarly, platelet production too can increase up to 10 times. Thus, although coagulation and fibrinolysis are in progress, platelet counts and fibrinogen levels may be normal or only marginally reduced although levels of FDPs are elevated.44,45 These patients rarely bleed spontaneously or from minor trauma, but have severe hemorrhage if subjected to surgery.

Decompensated DIC Hemorrhage from multiple sites is the dominant

manifestation of DIC. It commonly starts as bleeding from puncture sites after intravenous or intramuscular injections, and from the postpartum uterus or surgical wounds. Bleeding from mucosal sites follows particularly in obstetric patients. In severe cases, DIC is invariably accompanied by shock, either due to the underlying disorder or due to massive blood loss. Hypotension if prolonged can result in organ ischemia and dysfunction and acute tubular necrosis. The thrombotic manifestations of DIC may worsen organ hypoperfusion and severe renal insufficiency with acute cortical necrosis may result 2.Chronic DIC

In chronic DIC, smaller amounts of tissue factor are involved, resulting in much less intense stimulation of the coagulation system and allowing the body to compensate for the consumption of coagulation proteins and platelets.46 This refers to the conditions where mild bleeding and abnormal coagulation tests suggestive of low grade DIC persist for many weeks. Though the pathophysiology is identical to acute DIC, clinical picture and laboratory findings in chronic DIC may be wavering. Here, nearly all of the baseline tests like platelet count, fibrinogen, PT and APTT may be normal. FDP, fibrinopeptide A and D dimer however are usually raised and diagnostic. Malignancy is the major cause of this syndrome. Other causes include retained dead fetus, liver disease, aneurysm or hemangiomas. Sepsis usually causes acute DIC but nonovert chronic DIC may also be observed. Prognosis

The prognosis of DIC depends mainly on the underlying condition. Nevertheless, very low fibrinogen levels, post-operative DIC, coexisting hypotension, multiple organ failure, and systemic sepsis carry a poor prognosis. The overall mortality varies from 50 to 80 %.47,48

It is even more in obstetric cases than in non-obstetric cases. Diagnosis

The diagnosis of disseminated intravascular coagulation relies on clinical signs and symptoms, identification of the underlying disease, the results of laboratory testing, and differentiation from other pathologies. In general, the pathogenesis of DIC is characterized by simultaneous and ongoing activation of both hemostasis and fibrinolysis, resulting in extensive and persistent generation of thrombin and plasmin,49 as well as progressive consumption of coagulation factors and platelets, production of fibrin, and consequent fibrin(ogen) degradation products (FDPs). Levels of plasminogen activator inhibitor type 1 may also be elevated, suggesting some imbalance between the procoagulant and fibrinolytic process.50 A reduction in antithrombin levels, a depression of the protein C pathway, and inhibition of the tissue factor pathway inhibitor may also occur and aggravate the clinical

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course.51 The laboratory diagnosis of DIC thus uses a combination of these tests because no single test result alone can firmly establish or rule out the diagnosis.

The tests commonly used for assessment of DIC are platelet count, prothrombin time (PT), activated partial thromboplastin time, fibrinogen level, fibrin degradation product (FDP) assay and D-dimer assay, Because DIC is a dynamic process, repeat measurement is necessary. Baseline tests of hemostasis may initially provide evidence of coagulation activation and later in the process provide evidence of consumption of coagulation factors, but their individual diagnostic efficiency is limited.

Both PT and APTT are simple, rapid and inexpensive tests that are used for initial screening and assessment of coagulation pathway. Both these tests can be prolonged in patients being evaluated for reasons other than DIC. For example, trauma or other hemorrhage can lead to loss of blood and plasma components, so that prolonged coagulation tests may simply reflect this phenomenon rather than a pathological DIC process.52 Prolonged coagulation tests can also occur with hematologic malignancies unrelated to DIC. Because significant prolongations often occur at a late stage in DIC, this also compromises the overall efficiency of this test for an early diagnosis. Moreover, abnormal values may reflect pathology other than DIC,53 and normal values cannot be used to rule out the diagnosis.54

Thrombocytopenia is the hallmark of DIC, and its presence should prompt consideration of DIC. A low platelet count on initial testing and, in particular, a progressive drop in the platelet count are sensitive signs of DIC and may indicate ongoing thrombin-induced activation and use of platelets. The platelet count is considered a useful test in the diagnosis of DIC because it strongly correlates with markers of thrombin generation and because thrombin induced platelet aggregation advances platelet consumption. Moreover, the platelet count is not influenced by the acute-phase response. A single estimation of platelet count however might not reliably identify DIC, and serial estimations will provide more value in DIC diagnostics. One should also keep the possibility of many other underlying conditions associated with DIC (e.g., infections, malignancy, or anticancer therapy) as well as other life threatening pathologies (e.g., heparin-induced thrombocytopenia) can cause a low platelet count in the absence of DIC. Conversely, a stable platelet count suggests that intravascular platelet aggregation (and thrombin formation) is not occurring or has ceased

Fibrinogen levels often decline in patients with DIC, due to ongoing consumption. However, the overall sensitivity of plasma fibrinogen levels for the diagnosis of DIC is also low because this protein is a well-recognized acute-phase reactant, and levels may therefore be normal (particularly in the early developing phase of DIC and in patients with sepsis). Thus hypofibrinogenemia is usually

detected only in very severe cases of DIC or in the advanced stages of the disease. Similarly, like routine coagulation test times, depending on the clinical context, low fibrinogen levels can also reflect inherited or acquired pathologies other than DIC (e.g., afibrinogenemia, liver failure). However sudden or dramatic drop in fibrinogen level which may reflect massive consumption classically is characteristic of DIC. Markers of Fibrin Production and Breakdown

Elevated fibrin or FDPs (including D-dimer) and elevated soluble fibrin monomers are known to be highly sensitive for the diagnosis of DIC, and elevations of their values often precede overt DIC by several days.55,56 FDP consists of both fibrin and fibrinogen degradation products. Elevated levels of FDP reflect accelerated fibrinolysis due to plasmin and are found in 85% to 100% of patients with DIC. However, FDP is also elevated in various other conditions, including use of oral contraceptives, pulmonary emboli, myocardial infarction, renal disease, and arterial or venous thrombotic or thromboembolic events. Moreover, it may also be negative when measured using the latex agglutination assay when there is only a minimal consumptive process.

D-dimer is formed during fibrinolysis as a result of degradation of cross-linked fibrin by plasmin. D-dimer levels are elevated in almost all cases of DIC. In fact D-dimer testing has largely replaced most other markers of fibrinolysis in general clinical and laboratory practice, for both DIC and the diagnosis of other thrombotic disorders.

The natural anticoagulants, especially antithrombin and protein C, are frequently reduced in patients with DIC, and these reductions may also have prognostic significance. 66, 67 For example, a decrease in plasma antithrombin levels <50% of normal is strongly associated with increased mortality in patients with DIC due to sepsis,57 and in surgical patients with sepsis antithrombin levels <70% and 65%, are associated with a 90% and 100% mortality, respectively.58 Moreover, lower initial antithrombin levels in neonatal sepsis are associated with a severe disease and increased mortality. Antithrombin levels are found to provide the best prognostic value for prediction of subsequent death in patients affected by septic shock. Similarly low levels of activated protein C concentrations in neutropenic patients affected by septic shock has also been reported to provide a significant prognostic value.59

Although a significant decrease in the level of these natural inhibitors may provide valuable information for establishing a diagnosis of DIC and monitoring the clinical course of the disease, these tests are not commonly available in all laboratories, nor are they always available as an urgent test procedure. Moreover, the ISTH SSC on DIC recently concluded there is no added value in including their tests within the conventional scoring system.60 Nevertheless, their measurement might be helpful in selected situations, in assessing for non-overt DIC or the severity of DIC, in

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monitoring of therapy, and in an assessment of the prognosis.61

Serial coagulation tests are usually more helpful than single laboratory results in establishing the diagnosis of DIC (Table 2 and 3). Following are the tests that can help in diagnosis of DIC and assessing its clinical course. Among these the most widely used are complete blood picture and peripheral blood smear, PT, APTT, fibrinogen levels, FDPs and D-Dimers. Baseline laboratory tests/Screening Tests

Prothrombin time activated partial thromboplastin time, (which are dependent on the conversion of fibrinogen to fibrin polymer), are prolonged. Schistocytes may be seen in 50% of patients with fulminant DIC as a result of passage of red cells through fibrin strands. Likewise thrombocytopenia may be an initial finding in many of the patients.62

The derangements observed in above laboratory tests in DIC are as follows Specific Tests

Fibrin(ogen) degradation products (FDPs) are determined using latex agglutination test and thrombin clot tubes are used to remove any fibrinogen so that these latex particles do not falsely measure the fibrinogen as FDPs. However, the thrombin clot tubes remove not only fibrinogen, but also the early fragments X and Y, and so if fibrinolysis is in the early phase of activation wherein the lysis has not progressed beyond this stage, the FDPs would be falsely negative.

Table 2: Diagnostic Tests for DIC Screening Tests

Peripheral smear – Schistocytes Thrombocytopenia with large platelets Prolongation of PT, aPTT, TT

Specific Tests Elevated D-dimer & soluble fibrin monomer (sFM) Elevated fibrinogen degradation products (FDPs) Elevated fibrinopeptide A & fibrinopeptide B Decreased protein C and S Decreased antithrombin Elevated plasmin Decreased antiplasmin Elevated PAP complex Elevated TAT complex

Tests for end organ damage Elevated LDH Elevated creatinine

Moreover the available test method detects the D and E fragments only and so if the plasmin digestion has gone beyond this stage, then again the FDPs may not be detected inspite of profound fibrinolytic activity. Hence, a negative test for FDPs does not rule out DIC The measurement of D-dimer is the most sensitive and cost effective test and could

possibly replace the need to measure FDPs particularly in chronic DIC, most of the baseline laboratory tests such as PT, PTT, fibrinogen and platelets may be normal but D-dimer are always abnormal. D-Dimer is the only test that directly addresses both thrombin and plasmin generation. This is estimated most reliably by latex agglutination test using the monoclonal antibody against the D-dimer neo-antigen, that are specific for the cross-linked fibrin derivatives containing the D-dimer configuration. Tests for fibrin-degradation products or D-dimers are also helpful to differentiate disseminated intravascular coagulation from other conditions that are associated with a low platelet count or prolonged clotting times.

More specialized laboratory tests that are useful in the diagnosis of DIC include the measurement of soluble fibrin and sensitive assays that can measure the generation of thrombin, such as assays for the detection of prothrombin activation fragment F1+2 or thrombin–antithrombin complexes (TAT). Prothrombin fragments 1+2, fibrino-peptide A and thrombin-antithrombin (TAT) complex can all be reliably measured by enzyme linked immunosorbent assay (ELISA). The decrease in antithrombin is related to outcome, and plasma levels are significantly lower in non-survivors than in survivors. The soluble fibrin monomer (sFM), like the D-dimer, serves as a marker for both procoagulant and plasmin activation, and is measured by ELISA It is difficult to measure plasmin level in plasma since it is rapidly inactivated by anti plasmin and slowly by alpha-2-macroglobulin. PAP serves as a marker of fibrinolytic activation as well as inhibitor consumption. Plasmin-antiplasmin (PAP) complex can be measured by crossed immunoelectro-phoresis, ELISA and radioimmuno-assays. PAP is elevated early in DIC and changes in parallel with the course of DIC, with levels decreasing in clinical remission. A lower ratio of PAP/TAT points towards a poor prognosis and is associated with organ failure. Both TAT and PAP are more useful for diagnosing pre-DIC. Recently, tests have been developed to measure tissue plasminogen activator and tissue plasminogen activator inhibitor (PAI).62. Although they may be helpful in complicated clinical situations, they are usually not essential in general clinical practice

Table 3:Laboratory Features of Chronic DIC

Platelet count: usually normal or borderline Fibrinogen: normal/increased PT: normal/prolonged PTT: normal/prolonged Schistocytes: 90% patients FDP: usually increased Fibrinopeptide A: usually increased D dimer: usually increased

Antithrombin III measurement is of paramount importance not only for diagnosis but also for prognosis and therapy. It has been proved that no single test can make or

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refute the diagnosis of DIC. We have to look for multiple parameters carefully; particularly cases of chronic DIC have to be dealt with very cautiously before ruling out DIC. A scoring systems have been developed by the subcommittee on DIC of the International Society of Thrombosis and Hemostasis (ISTH) and by the Japanese Association for Acute Medicine (JAAM).

Both systems have been prospectively validated and have a high diagnostic rate; however, the JAAM criteria appear to have an advantage for diagnosing the patient with early DIC.63 Risk assessment Does the patient have an underlying disorder known to be associated with overt DIC? NO YES Do not use this algorithm Order baseline coagulation tests (platelet count, prothrombin time, fibrinogen), soluble fibrin monomers, or fibrin degradation products) Score global coagulation test results Test Score Platelet count (cells/mL) 100,000 = 0 < 100,000 = 1 < 50,000 = 2 Elevated fibrin related marker No increase = 0Moderate increase = 2 Strong increase = 3 Prolonged Prothrombin time < 3 sec = 0 > 3 but < 6 sec = 1 > 6 sec = 2 Fibrinogen level (g/L) 1 = 0 < 1 = 1 Calculate score ≥ 5 is compatible with overt DIC; repeat scoring daily < 5 is suggestive (not affirmative) of non overt DIC; repeat scoring next 1 to 2 days Overt DIC refers to a decompensated hemostatic system, Non overt DIC refers to a stressed but compensated hemostatic system. Japanese Association for Acute Medicine Scoring System for DIC Criteria Score Systemic inflammatory response syndrome criteria ≥ 3 1 0–2 0 Platelet count (cells/μl) < 80,000 or > 50% decrease within 24 hr 3 ≥ 80,000 and < 120,000 or > 30% decrease within 24 hr 1 ≥ 120,000 0 Prothrombin time (patient’s value/normal value) ≥ 1.2 1 < 1.2 0 Fibrin/fibrinogen degradation products (mg/L) ≥ 25 3

≥ 10 and < 25 1 < 10 0 A score of ≥ 4 indicates a diagnosis of disseminated intravascular coagulation. Management of DIC The heterogeneity of DIC has made it difficult to diagnose and treat these patients. The wide range of manifestations ranging from thrombosis to hemorrhage, difficulty in quantifying response to therapy, presence of coexisting multiple organ failure and varying prognosis of the underlying disease have made evaluation and treatment of these patients difficult. As there is always a triggering disease in the background of DIC and the outcome of DIC depends mainly on the triggering disease, the first and foremost step is to deal the triggering factor. The next logical step is the use of anticoagulants so as to hold the process of thrombosis. However controversy exists here as the use of anticoagulant in the phase of hemorrhage might aggravate bleeding. In general when bleeding is prominent due to consumption of factors, one would be inclined to use replacement therapy to control bleeding should be considered. Various therapeutic options which should be taken into consideration in managing the patients of DIC include: General measures Treatment of the triggering disease: The most important guiding principle for therapy of DIC is to identify the triggering disease and manage it aggressively. In addition, it is equally important to provide supportive care for optimizing hemodynamic stability, maintaining adequate oxygenation and acid base balance. A derangement of any of these would by themselves serve to trigger and aggravate DIC. Blood component therapy: Decision regarding component therapy is based on whether the patient is bleeding and if an invasive procedure is planned. Replacement of depleted blood components helps to control blood loss and this may be maximally evident only after the consumptive process has been interrupted. However, some think that component therapy in patients with continuing consumption may 'add fuel to the fire' by increasing microcirculation thrombosis, worsening of the coagulopathy. They do not agree with the use of the component therapy unless the antithrombin level is normalized. Fresh frozen plasma and cryoprecipitate are the preferred blood components.64 Fresh plasma provides all clotting factors and antithrombotic proteins. However, fibrinogen may not increase with replacement of plasma alone and cryoprecipitate provides greater quantities of fibrinogen and is often required when serum fibrinogen level is very low to start with. A general recommendation is to start with 4 to 6 units of fresh frozen plasma and 2 to 3 units of cryoprecipitate and reassess the clotting profile. A platelet count less than 50,000 per/µl or persistent bleeding.

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Coagulation system Inhibitors of coagulation

Intrinsic system Extrinsic system Thrombin + Thrombomodulin

Protein C Protein S

X Xa fV & FVIII activation

PF (1+2) APC + fPS bound PS

Prothrombin Thrombin Antithrombin (PS+C4b)

Inhibition of f V + f VIII

fpA+ fpB TAT complex

Fibrinogen Fibrin monomer Fibrin polymer D dimers

a FXIII

X and Y D and E sFM

fragments fragments

Antiplasmin

Plasmin PAP complex

Platelet aggregation

Plasminogen

Fibrinolytic system

Abbreviations

PF=Prothrombin fragment APC= Activated protein S f PS= Free protein S

b PS= Bound Protein S s FM= Soluble fibrin monomers PAP=Plasmin antiplasmin complex

Heparin therapy: Heparin is an effective anticoagulant and its anticoagulant effect is produced by inhibiting thrombin

Pathogenesis of DIC

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formation and function. Although consumption of coagulation factors may be interrupted with heparin therapy, the bleeding complications may increase. Anticoagulant response with heparin alone may not be effective due to low levels of antithrombin in DIC. Thus, the role of heparin in DIC has always been controversial it should thus be very cautiously used and carefully monitored. Low molecular weight heparin appears to offer the benefit of decreased bleeding complications compared to unfractionated heparin in the treatment of DIC. When heparin is used, it is administered at a dose of 15 U/kg/hr as a continuous infusion. Some prefer subcutaneous administration of Heparin at a dose of 80-100 U/kg every 4-6.66 In general heparin should be used in DIC when it shows the features of thrombotic manifestations such as end organ failures. Heparin should not be used in DIC with head trauma, massive liver failure and obstetrical accidents. There are no adequate studies of heparin use in DIC with sepsis. Inhibitor therapy: Various inhibitors of coagulation such as antithrombin, protein C and tissue factor pathway inhibitor (TFPI) also play very important role in managing these patients Antithrombin III: Of these inhibitors, the role of antithrombin seems most promising. About 90% of patients with DIC have very low serum antithrombin III levels. This may be an important factor, which sustains the coagulopathy. Many studies in obstetric and non-obstetric DIC have shown that simultaneous infusion of antithrombin III and heparin produce clinical improvement and correction of coagulation defects within 2 hours.67 The initial dose of 2500 units of antithrombin III (40 mg/kg) is followed by a continuous infusion of 50 units/ hour. Clinical studies have shown a trend towards improved survival of DIC with sepsis when antithrombin was administered alone or with heparin. 79 Antithrombin is effective in inhibiting thrombin generation and does not have the risk of inducing bleeding, and so seems to be a better alternative than heparin in halting the unwanted clotting process particularly in sepsis. One study regarding use of antithrombin III in patients with DIC, was conducted in Japan and published in October 2009 and suggested that a significant reduction in the DIC score and an improvement in the prothrombin time ratio was observed with small dose of antithrombin III in sepsis-associated DIC.68 Activated Protein C (APC): Inactivates fVa and f VIIIa, thus decreasing thrombin formation and promotes fibrinolysis by complex formation with PAI. APC has been used particularly in meningococcemia and recent trials have suggested that in a relatively small dosage APC can improve DIC more efficiently than can heparin, without increasing bleeding.69 TFPI is also a specific inhibitor of the tissue factor-VIIIa complex, thereby inhibiting intravascular coagulation and its use has improved the outcome in these patients particularly when underlying cause is sepsis.70

Antifibrinolytic agents: Antifibrinolytic agents such as epsilon-aminocaproic acid and tranexamic acid are rarely needed in DIC; one exception to this is acute promyelocytic leukemia patients in whom there may be primary activation of the fibrinolytic system 83. However the use of these agents can potentially aggravate intravascular thrombosis. Thus, antithrombolytic drugs are contraindicated in DIC, although they remain drugs of choice in primary fibrinolysis where fibrinogen is lysed in the absence of thrombosis. They are indicated in DIC only when bleeding continues inspite of using the other treatment modalities. Therapy of chronic DIC: Therapy of underlying disease is most important part of management for both acute and chronic DIC. Patients with chronic DIC are initially treated with anti-coagulant doses of heparin to maintain a PTT 1.5-2 times normal. In other cases of chronic DIC, low dose (5-10U/kg/hour) of heparin may be sufficient to reverse the coagulopathy.71 Heparin therapy is contra-indicated in patients with intracranial meta-static disease and chronic DIC. Differential Diagnosis Microangiopathic Hemolytic Anemia (MAHA) MAHA comprise thrombocytopenic thrombotic purpura, the hemolytic– uremic syndrome, chemotherapy-induced. Although some characteristics of MAHA and the resulting thrombotic occlusion of small and midsize vessels may mimic the clinical picture of DIC, these disorders are a distinct group of diseases. The common feature of MAHA appears to be endothelial damage, which causes the adhesion and aggregation of platelets, the formation of thrombin, and the impairment of fibrinolysis. Mucosal bleeding along with renal and cerebral dysfunction, presence of thrombocytopenia and schistocytes in peripheral blood and normal coagulation profile are the indicators of MAHA. Although hemolytic anemia and schistocytes are also sometimes present in patients with severe DIC(because of the presence of intravascular fibrin), these are invariable findings in patients with MAHA. Liver Disease: Coagulopathy in liver disease is usually due to inadequate hepatic synthesis of clotting factors. Thrombocytopenia and FDP levels may help in differentiating between these conditions but splenic sequestration of platelets may make this distinction blurred. Estimation of factor VIII levels is useful - it is low in DIC but normal in liver disease due to its synthesis at non- hepatic sites. Primary Fibrinolysis: Primary fibrinogenolysis may occur in many conditions which also cause DIC like snake bite, prostatic carcinoma or prostatic surgery, mucinous adenocarcinomas and large hemangiomas. Fibrinogen is lysed without accompanying microcirculatory thrombosis. The diagnosis of Primary Fibrinolytic Syndrome has to be kept in mind upon any further difficulty in establishing the differential diagnosis for DIC.72 Antifibrinolytic agents

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which are contraindicated in DIC are extremely useful in this condition

References 1. Marder VJ, Feinstein DI, Francis CW and Colman RW et al.

Consumptive Thrombohemorrhagic disorders.. Hemostasis and thrombosis: basic principles and clinical practice. 3rd ed. Philadelphia: J.B. Lippincott, 1994:1023-63.

2. Müller-Berghaus G, ten Cate H, Levi MM. Disseminated intravascular coagulation. In: Verstraete M, Fuster V, Topol EJ, eds. Cardiovascular thrombosis: thrombocardiology and thromboneurology. 2nd ed. Philadelphia: Lippincott-Raven, 1998:781-801

3. Levi M and Cate H.et al Disseminated Intravascular Coagulation. The New England Journal of Medicine 1999; 341(8):587-592

4. Taylor Jr FB, Toh CH, Hoots WK, Wada H and Levi M.et al. clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation—on behalf of the Scientific Subcommittee on disseminated intravascular coagulation (DIC) of the International Society on Thrombosis and Hemostasis (ISTH). Thromb Haemost 2001; 86: 1327– 30.

5. Favaloro EJ. et al. Laboratory Testing in Disseminated Intravascular Coagulation. Seminars in Thrombosis and Hemostasis 2010; 36 (4): 458-467.

6. Hamilton PJ. Stalker AL and Douglous AS et al. Disseminated intravascular coagulation; a review. Journal of Clinical Pathology 1978; 31:609-619

7. Saba HI, Morelli GA. The pathogenesis and management of disseminated intravascular coagulation. Clin Adv Hematol Oncol 2006; 4: 919–26.

8. Levi M, van der Poll T and ten Cate H.et al Tissue factor in infection and severe inflammation. Semin Thromb Hemost 2006; 32:33–9.

9. Levi M, de Jonge E, van der Poll T. Rationale for restoration of physiological anticoagulant pathways in patients with sepsis and disseminated intravascular coagulation. Crit Care Med 2001; 29(7): 90–4.

10. Esmon CT.et al. Role of coagulation inhibitors in inflammation. Thromb Haemost 2001; 86:51–6.

11. Nawroth PP and Stern DM.et al. Modulation of endothelial cell hemostatic properties by tumor necrosis factor. J Exp Med. 1986; 163:740-745.

12. Conway EM and Rosenberg RD.et al. Tumor necrosis factor suppresses transcription of the thrombomodulin gene in endothelial cells. Mol Cell Biol. 1988; 8: 5588-5592.

13. Kienast J, Juers M, Wiedermann CJ, et al. Treatment effects of high-dose antithrombin without concomitant heparin in patients with severe sepsis with or without disseminated intravascular coagulation. J Thromb Hemost 2006; 4:90–7.

14. James J and Corrigan Jr.et al. Disseminated Intravascular Coagulopathy Pediatr. Rev. 1979; 1; 37-45.

15. Warren BL, Eid A, Singer P, Pillay SS, Carl P and Novak I, et al. High-dose antithrombin in severe sepsis. A randomized controlled trial. JAMA 2001; 286: 1869–78.

16. Abraham E, Reinhart K, Opal S, Demeyer I, Doig C, Rodriguez AL, et al. Efficacy and safety of tifacogin (recombinant tissue factor pathway inhibitor) in severe sepsis: a randomized controlled trial. JAMA 2003;290: 238–47

17. Okamoto K, Wada H, Hatada T, Uchiyama T and Kawasugi K et al. Frequency and hemostatic abnormalities in pre-DIC patients. Thrombosis Research 126 (2010) 74–78.

18. Thijs LG, de Boer JP, de Groot MCM,and Hack CE et al. Coagulation disordersin septic shock. Intensive Care Med 1993; 19(1): 8-15.

19. Gando S, Kameue T, Nanzaki S and Nakanishi Y et al. Disseminated intravascular coagulation is a frequent complication of systemic inflammatory response syndrome. Thromb Haemost 1996; 75: 224-8.

20. Barretab JP and Gomezb PA. et al. Disseminated intravascular coagulation: a rare entity in burn injury 2005;31(3): 354-357

21. Colman RW and Rubin RN.et al. Disseminated intravascular coagulation due to malignancy. Semin Oncol 1990;17: 172-86.

22. Sarris AH, Kempin S, Berman E, et al. High incidence of disseminated intravascular coagulation during remission induction of adult patients with acute lymphoblastic leukemia. Blood 1992; 79:1305-10.

23. Tao Jin, Hai-Yong Wang and Yi-Ming Ni Disseminated Intravascular Coagulopathy Caused by Intra-cardiac Mesothelioma Asian Cardiovasc Thorac Ann 2006;14:517-519

24. Levi M and Ten Cate H. et al. Disseminated intravascular coagulation. N Engl J Med 1999; 34: 586–92.

25. Saba HI and Morelli GA et al. The pathogenesis and management of disseminated intravascular coagulation. Clin Adv Hematol Oncol 2006; 4: 919–26.

26. Malik Zeb Khan1, Muhammad Shoaib Khan1, Fazle Raziq1, Aziz Marjan Khattak2 fibrinogen degradation products and D-dimers in patients with breast carcinoma Gomal Journal of Medical Sciences Jan–June, 2007, Vol. 5, No. 1

27. Hideki Uchiumi, Takafumi Matsushima, Arito Yamane, Noriko Doki and Hiroyuki Irisawa et al. Prevalence and Clinical Characteristics of Acute Myeloid Leukemia Associated with Disseminated Intravascular Coagulation International Journal of Hematology 2007; 86 137-142.

28. Qazi RA and Hameed B et al Bleeding diathesis in acute Myeloid Leukemia: Thrombocytopenia alone or in Disseminated Intravascular Coagulopathy J Pak Inst Med Sci Dec 2002;13 (2):682-5.

29. Anwar M, Anwar MJ, Ayub M, Zafar T and Saleem M.et al. Disseminated intravascular coagulation in acute lymphoblastic leukaemia Pak J Pathol.1997;8(4):4-7

30. Higuchi T, Toyama D, Hirota Y, et al. Disseminated intravascular coagulation complicating acute lymphoblastic leukemia: a study of childhood and adult cases. Leuk Lymphoma. 2005; 46: 1169- 1176.

31. Okamoto K, Wada H, Hatada T and Uchiyama T et al. Frequency and hemostatic abnormalities in pre-DIC patients. Thrombosis Research 2010; 126: 74–78

32. Rodger L. Bick et al. Syndromes of DIC in obstetrics, pregnancy, and gynecology: Objective Criteria for Diagnosis and management. Hematology/Oncology 2000; 14 (5) : 999-1044

33. Morgan M. Amniotic fluid embolism. Anaesthesia. 1979; 34 (1):20-32. cited by Sumeet Kumar S, Wong G, Maysky M and Mark Shulman M. et al, Amniotic fluid embolism complicated by paradoxical embolism and disseminated intravascular coagulation American Association of Critical-Care Nurses 2009

34. Clark SL, Hankins GD, Dudley DA, Dildy GA and Porter TF et al. Amniotic fluid embolism: analysis of a national registry. Am J Obstet Gynecol. 1995;172 (4 ):1158-1169.

35. Gilbert WM and Danielsen B et al. Amniotic fluid embolism: decreased mortality in a population-based

Haematology Updates 2010

137

study. Obstet Gynecol. 1999; 93(6):973-997, Cited by Kumar S, Wong G, MD, Maysky M et al. Amniotic fluid embolism complicated by paradoxical embolism and disseminated intravascular coagulation American Association of Critical-Care Nurses 2009

36. Courtney LD, and Allington M.et al. Effect of amniotic fluid on blood coagulation. Br J Haematol. 1972; 22 (3):353-355.

37. Sibai BM, Spinnato JA, Watson DL, Hill GA, Anderson GD. Pregnancy outcome in 303 cases with severe preeclampsia. Obstet Gynecol 1984; 64: 319-25.

38. Tayyib M, Mengal M, Tasneem T, Ditta A and Farooq M et al. Fibrinogen degradation products and D-Dimer study in patients with Pre-Eclampsia Pak Postgrad Med J Mar 2003; 14 (1):10-3.

39. Ghazi A, Siddiq NM, Ali T, Jabbar S and Muhammad WZ et al. Deranged coagulation profile among obstetric patients Pak J Surg Apr - Jun 2008;24 (2):135-7

40. Amer Mushtaq M et al Disseminated Intravascular Coagulation in a patient with HELLP syndrome Pak J Med Sci Jan - Mar 2005;21(1):90-4.

41. Sibia BM, Ramdan MK, IUsta M and Mercer BM et al. Maternal Morbidity and 442 pregnancies with HELLP Syndrome. JAMA 1993 270 (8) 975- 9.

42. Szlachetka DM.et al. Kasabach-Merritt syndrome: a case review. Neonatal Netw 1998; 17(3): 21.

43. Aboulafia DM and Aboulafia ED.et al Aortic aneurysm-induced disseminated intravascular coagulation. Ann Vasc Surg 1996; 10:396-405.

44. Matsuda T.et al Clinical aspects of Disseminated intravascular coagulation. Pol J Pharmacol 1996; 48 : 73

45. Bang NU. Diagnosis and management of thrombosis. In: Shoemaker WC, Ayers S, Grenvik A, Holbrook PR, Thompson WI, editors. Textbook of Critical Care, 2nd ed. Philadelphia: WB Saunders; 1989, pp 886-895

46. Sharp AA.et al Diagnosis and management of disseminated intravascular coagulation. Br Med Bull 1977; 33:265-272.

47. Marder VJ. Consumptive thrombohemorrhagic disorders. In: Williams WJ, Beutier E, Ersler AJ, Lichtman MA, editors. Hematology, 4th ed. Philadelphia: JB Lippincott; 1989, p 1522-1543.

48. Benny Kusuma, MD Thomas K. Schulz, MD. Acute Disseminated Intravascular Coagulation Hospital Physician 2009; 35-40

49. Ulrich A. Antithrombin and related inhibitors of coagulation. In: Poller L, editor. Recent advances in Blood Coagulation. 2, Edinburgh: Churchill Livingstone; 1981; 151-173.

50. Feinstein DI. et al Diagnosis and management of disseminated intravascular coagulation: role of heparin therapy. Blood 1982; 60:284-287

51. Horan JT, Francis CWet al. Fibrin degradation products, fibrin monomer and soluble fibrin in disseminated intravascular coagulation. Semin Thromb Hemost 2001;27(6):657–666

52. Hack CE.et al. Fibrinolysis in disseminated intravascular coagulation. Semin Thromb Hemost 2001;27(6):633–638

53. Levi M, van der Poll T.et al The role of natural anticoagulants in the pathogenesis and management of systemic activation of coagulation and inflammation in critically ill patients. Semin Thromb Hemost 2008;34(5):459–468

54. Favaloro EJ et al. Laboratory Testing in Disseminated Intravascular Coagulation Semin Thromb Hemost 2010;36:458–468

55. Lippi G, Favaloro EJ et al. Activated partial thromboplastin time: new tricks for an old dogma. Semin Thromb Hemost 2008; 34(7):604–611

56. Bick RL. et al. Disseminated intravascular coagulation: pathophysiological mechanisms and manifestations. Semin Thromb Hemost 1998;24(1):3–18

57. Wada H, Sakuragawa N, Mori Y, et al. Hemostatic molecular markers before the onset of disseminated intravascular coagulation. Am J Hematol 1999;60(4):273–278

58. Wada H, Sakuragawa N.et al. Are fibrin-related markers useful for the diagnosis of thrombosis? Semin Thromb Hemost 2008;34(1):33–38

59. De Jonge E, van der Poll T, Kesecioglu J and Levi M. et al Anticoagulant factor concentrates in disseminated intravascular coagulation: rationale for use and clinical experience. Semin Thromb Hemost 2001; 27(6):667–674

60. Levi M, Toh CH, Thachil J and Watson HG et al; British Committee for Standards in Haematology. Guidelines for the diagnosis and management of disseminated intravascular coagulation. Br J Haematol 2009;145(1):24–33

61. Wiedermann CJ et al. Clinical review: molecular mechanisms underlying the role of antithrombin in sepsis. Crit Care 2006; 10(1):209

62. Wilson RF, Mammen EF, Robson MC, Heggers JP, Soullier G and DePoli PA et al. Antithrombin, prekallikrein, and Fibronectin levels in surgical patients. Arch Surg 1986;121(6):635–640

63. Mesters RM, Helterbrand J, Utterback BG, et al. Prognostic value of protein C concentrations in neutropenic patients at high risk of severe septic complications. Crit Care Med 2000;28(7):2209–2216

64. Toh CH, Hoots WK; SSC on Disseminated Intravascular Coagulation of the ISTH. The scoring system of the Scientific and Standardisation Committee on Disseminated Intravascular Coagulation of the International Society on Thrombosis and Haemostasis: a 5-year overview. J Thromb Haemost 2007;5(3):604–606

65. Cauchie P, Cauchie Ch, Boudjeltia KZ, et al. Diagnosis and prognosis of overt disseminated intravascular coagulation in a general hospital—meaning of the ISTH score system, fibrin monomers, and lipoprotein-C-reactive protein complex formation. Am J Hematol 2006;81(6):414–419

66. Marcel M, Alvin L, Schmaier H and Robert W et al

Disseminated Intravascular Coagulation: Differential Diagnoses & Workup Indian pediatric journal 2003; 40;721-730

67. Wada H, Wakita Y, Nakase T, Shimura M and Hiyoyama K et al. Diagnosis of pre-disseminated intravascular coagulation stage with hemostatic molecular markers. The Mie Study Group. Polish J Pharm 1996; 48: 225-228.

68. Greengard JS, Griffin H. Protein C pathways. In: Hoffibrand AV, editor. Recent Advances in Haematology, 5, Edinburgh: Churchill Livingstone; 1988, pp 275-289.

69. Vasani.J.K. et al. Disseminated intravascular coagulation: a review with experience from an intensive care unit in India. Journal of postgraduate medicine, 1992;38(4): 186-93

70. Benny Kusuma and Thomas K et al. Acute Disseminated Intravascular Coagulation Hospital Physician; 2009: 35-40

71. Haak HL, Stolk JC, Gratama JW, van Hulsteyn H and Briet E et al.Use of antithrombin III concentrates in stable diffuse intravascular coagulation. Acta Haematol 1982; 68:28-33.

Haematology Updates 2010

138

72. Fourrier F, Chopin C, Huart JJ, Runge I, Caron C and Goudemand J et al. Double-blind, placebo-controlled trial of antithrombin III concen-trates in septic shock with

disseminated intravascular coagulation. Chest 1993; 04: 82-888