Thromboelastometry for the assessment of coagulation abnormalities in early and established adult sepsis: a prospective cohort study

Rotation thromboelastometry and the hypercoagulable state in Cushing's syndrome

INTRODUCTION

Rotation thromboelastometry (ROTEM®) can be used for hypercoagulability evaluation. Cushing's syndrome (CS) is associated with hypercoagulability; however, ROTEM® has never been evaluated in this setting.

OBJECTIVE

To evaluate hypercoagulability in CS using ROTEM® and to correlate these parameters with coagulation markers and with the presence of deep vein thrombosis.

DESIGN AND METHODS

Thirty patients with active CS (26 women) and 30 controls matched for age, sex, body mass index, diabetes mellitus, arterial hypertension, ABO blood group and smoking were included. We measured levels of activated partial thromboplastin time (aPTT), platelets, fibrinogen, D-dimer, factor VIII (FVIII), von Willebrand factor (vWF) and C-reactive protein. ROTEM® was used to evaluate the intrinsic (INTEM), extrinsic (EXTEM) and fibrinogen (FIBTEM) pathways. Doppler ultrasonography was performed to search for lower limbs deep vein thrombosis.

RESULTS

INTEM clotting time using ROTEM® was shorter in patients than in controls (P = 0·04). Other ROTEM® parameters were not different. Mean aPTT was shorter in patients than in controls (P = 0·001). The FVIII, vWF and D-dimer levels were higher in patients than in controls (P = 0·001, 0·001 and 0·02, respectively). Obese CS patients presented higher levels of platelets and alterations in maximum clot formation (MCF), alpha angle and maximum speed of clot formation of INTEM (P = 0·03, 0·02 and 0·02, respectively) and an increase in the MCF of FIBTEM (P = 0·02). No deep vein thrombosis was found.

CONCLUSIONS

Although FVIII and vWF were abnormal in CS patients, only the initiation clot formation was different in the ROTEM® methodology and no deep vein thrombosis was found.

Histone deacetylase inhibitor treatment attenuates coagulation imbalance in a lethal murine model of sepsis

BACKGROUND

Sepsis has a profound impact on the inflammatory and hemostatic systems. In addition to systemic inflammation, it can produce disseminated intravascular coagulation, microvascular thrombosis, consumptive coagulopathy, and multiple organ failure. We have shown that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDACI), improves survival in a lethal model of cecal ligation and puncture (CLP) in mice, but its effect on coagulation remains unknown. The goal of this study was to quantify the impact of SAHA treatment on coagulopathy in sepsis.

METHODS

C57BL/6J mice were subjected to CLP, and 1 hour later given intraperitoneally either SAHA dissolved in dimethyl sulfoxide (DMSO) or DMSO only. Sham-operated animals were handled in similar manner without CLP. Blood samples were collected by cardiac puncture and evaluated using the TEG 5000 Thrombelastograph Hemostasis Analyzer System.

RESULTS

Compared with the sham group, all animals in DMSO vehicle group died within 72 hours, and developed coagulopathy that manifested as prolonged initial fibrin formation and fibrin cross-linkage time, and decreased clot formation speed, platelet function, and clot rigidity. SAHA treatment significantly improved survival and was associated with improvement in fibrin cross-linkage and clot formation, as well as platelet function and clot rigidity, without a significant impact on the clot initiation parameters.

CONCLUSION

SAHA treatment enhances survival and attenuates sepsis-associated coagulopathy by improving fibrin cross-linkage, rate of clot formation, platelet function, and clot strength. HDACI may represent a novel therapeutic strategy for correcting sepsis-associated coagulopathy.

Diagnosis of overt disseminated intravascular coagulation in critically Ill adults by Sonoclot coagulation analysis

Disseminated intravascular coagulation (DIC) diagnosis is hampered by the limited availability of reliable clinical or laboratory tests. Currently available tests are time consuming and expensive. We investigated whether coagulation and platelet function analyses using the Sonoclot system were suitable for overt DIC diagnosis in critically ill adults. This was an observational diagnostic study performed in 498 patients presenting with an underlying disorder associated with DIC. Overt DIC patients were identified according to an International Society on Thrombosis and Hemostasis (ISTH) score of >5. Coagulation and platelet parameters were analyzed using the Sonoclot system, and compared with ISTH as the gold standard. Receiver operating characteristic curves and area under the curves were used to evaluate the value of the Sonoclot parameters. There were no differences for age or gender between the groups. Significant correlations were observed between activated clotting time (ACT) and ISTH score (r = 0.7; P < 0.001), clot rate (CR) and ISTH score (r = 0.5; P < 0.001), platelet function (PF) and ISTH score (r = -0.6; P < 0.001), and PF and platelet count (r = 0.5; P < 0.001). An ACT cut-off value of 213.5 s alone or combined with CR presented good sensitivity (76.7 and 86.8 %, respectively) and specificity (96.2 and 93.3 %, respectively). Sonoclot analysis can be performed using a point-of-care device that effectively discriminates low and high ISTH scores, and that effectively predicts coagulation dysfunction in patients with overt DIC.

Thromboelastometry as a supplementary tool for evaluation of hemostasis in severe sepsis and septic shock

BACKGROUND

Sepsis leads to disruption of hemostasis, making early evaluation of coagulation essential. The aim of this study was to provide a detailed investigation of coagulation and the use of blood products in patients with severe sepsis or septic shock, admitted to a multidisciplinary intensive care unit.

METHODS

Thirty-six patients with severe sepsis or septic shock were included in this prospective observational study. Blood samples and information on transfusion of blood products were obtained for up to 3 consecutive days, and day 7 if the patient was still in the intensive care unit. Thromboelastometry (ROTEM(®)), analyses of thrombin generation, and conventional coagulation tests were performed.

RESULTS

ROTEM(®) revealed an overall normo-coagulable state among patients with severe sepsis or septic shock. Conventional coagulation analyses showed divergent results with hypercoagulable trends in terms of reduced antithrombin and acute phase response with increased fibrinogen and fibrin d-dimer, and on the other hand, coagulation disturbances with a decreased prothrombin time and prolonged activated partial thromboplastin time. This hypocoagulabe state was supported by a delayed and reduced thrombin generation. Twelve patients experienced 21 independent transfusion episodes with fresh frozen plasma. Of these, only five (22%) transfusions were performed because of active bleeding.

CONCLUSION

ROTEM(®) demonstrated an overall normo-coagulation, whereas the conventional coagulation tests and thrombin generation analyses mainly reflected hypocoagulation. Given the dynamic and global features of ROTEM(®), this analysis may be a relevant supplementary tool for the assessment of hemostasis in patients with severe sepsis or septic shock.

Utility of thromboelastography and/or thromboelastometry in adults with sepsis: a systematic review

Introduction

Coagulation abnormalities are frequent in sepsis. Conventional coagulation assays, however, have several limitations. A surge of interest exists in the use of point-of-care tests to diagnose hypo- and hypercoagulability in sepsis.

We performed a systematic review of available literature to establish the value of rotational thromboelastography (TEG) and thromboelastometry (ROTEM) compared with standard coagulation tests to detect hyper- or hypocoagulability in sepsis patients. Furthermore, we assessed the value of TEG/ROTEM to identify sepsis patients likely to benefit from therapies that interfere with the coagulation system.

Methods

MEDLINE, EMBASE, and the Cochrane Library were searched from 1 January 1980 to 31 December 2012. The search was limited to adults, and language was limited to English. Reference lists of retrieved articles were hand-searched for additional studies. Ongoing trials were searched on http://www.controlled-trials.com and http://www.clinicaltrials.gov. Studies addressing TEG/ROTEM measurements in adult patients with sepsis admitted to the ICU were considered eligible.

Results

Of 680 screened articles, 18 studies were included, of which two were randomized controlled trials, and 16 were observational cohort studies. In patients with sepsis, results show both hyper- and hypocoagulability, as well as TEG/ROTEM values that fell within reference values. Both hyper- and hypocoagulability were to some extent associated with diffuse intravascular coagulation. Compared with conventional coagulation tests, TEG/ROTEM can detect impaired fibrinolysis, which can possibly help to discriminate between sepsis and systemic inflammatory response syndrome (SIRS). A hypocoagulable profile is associated with increased mortality. The value of TEG/ROTEM to identify patients with sepsis who could possibly benefit from therapies interfering with the coagulation system could not be assessed, because studies addressing this topic were limited.

Conclusion

TEG/ROTEM could be a promising tool in diagnosing alterations in coagulation in sepsis. Further research on the value of TEG/ROTEM in these patients is warranted. Given that coagulopathy is a dynamic process, sequential measurements are needed to understand the coagulation patterns in sepsis, as can be detected by TEG/ROTEM.

Thromboelastographic Study of Psychophysiological Stress: A Review

Thromboelastography (TEG) is drawing more attention for clinical and laboratory studies of hemostasis. It has been applied to evaluate the effects of both psychological and physiological stress on whole blood coagulation from the onset of the coagulation cascade through clot formation, to the end with fibrinolysis. We conducted a comprehensive review on the applications of TEG for assessment of different stressors, ranging from physical exercise to emotional situations. The methodology is unique in terms of instrumentation, the methods to activate blood coagulation, the type of blood (citrated vs fresh blood), and study settings (in vitro vs in vivo vs clinical trials). Thromboelastography has most often been used to study the effects of physiological stress. The author's own work and future directions are discussed as well. The review would facilitate future development of TEG for evaluating hemostasis and potential pathological pathways in response to various forms of stress.

Systemic endotoxin activity correlates with clot formation: an observational study in patients with early systemic inflammation and sepsis

Introduction

Inflammation and coagulation are closely linked, and both can be triggered by endotoxin. Thrombelastometry and impedance aggregometry are of diagnostic and predictive value in critically ill patients. In this observational study we investigated the correlation of endotoxin activity with thrombelasometric and aggregometric variables in patients with systemic inflammation.

Methods

Based on a daily screening on a tertiary academic surgical ICU, patients, as soon as they fulfilled two or more criteria for systemic inflammatory response syndrome (SIRS), were included. In whole blood we performed endotoxin activity (EA) assay, thrombelastometry (ROTEM^®) and impendance aggregometry (Multiplate^®).

Results

In total, 49 patients were included with a broad spread of EA levels of (median (minimum to maximum)) 0.27 (0.01 to 0.72), allowing expedient correlative analysis. Clot formation time (CFT) (263 s (60 to 1,438 s)) and clotting time (CT) (1,008 s (53 to 1,481 s)) showed a significant negative correlation with EA level (r = -0.38 (P < 0.005) and r = -0.29 (P < 0.05)). Positive correlations were found for alpha-angle (50° (17 to 78°), r = 0.40 (P < 0.005)) and maximum clot firmness (MCF) (55 mm (5/76), r = 0.27 (P < 0.05)). No significant correlations were found between Lysis Index at 60 minutes (LI60) and EA levels. There was no correlation between EA level and aggregometric values, or classical coagulation parameters.

Conclusions

In patients with systemic inflammation, increasing endotoxin concentrations correlate with increased clot formation.

Discrepant fibrinolytic response in plasma and whole blood during experimental endotoxemia in healthy volunteers

Background

Sepsis induces early activation of coagulation and fibrinolysis followed by late fibrinolytic shutdown and progressive endothelial damage. The aim of the present study was to investigate and compare the functional hemostatic response in whole blood and plasma during experimental human endotoxemia by the platelet function analyzer, Multiplate and by standard and modified thrombelastography (TEG).

Methods

Prospective physiologic study of nine healthy male volunteers undergoing endotoxemia by means of a 4-hour infusion of E. coli lipopolysaccharide (LPS, 0.5 ng/kg/hour), with blood sampled at baseline and at 4 h and 6 h. Physiological and standard biochemical data and coagulation tests, TEG (whole blood: TEG, heparinase-TEG, Functional Fibrinogen; plasma: TEG±tissue-type plasminogen activator (tPA)) and Multiplate (TRAPtest, ADPtest, ASPItest, COLtest) were recorded. Mixed models with Tukey post hoc tests and correlations were applied.

Results

Endotoxemia induced acute SIRS with increased HR, temperature, WBC, CRP and procalcitonin and decreased blood pressure. It also induced a hemostatic response with platelet consumption and reduced APTT while INR increased (all p<0.05). Platelet aggregation decreased (all tests, p<0.05), whereas TEG whole blood clot firmness increased (G, p = 0.05). Furthermore, during endotoxemia (4 h), whole blood fibrinolysis increased (clot lysis time (CLT), p<0.001) and Functional Fibrinogen clot strength decreased (p = 0.049). After endotoxemia (6 h), whole blood fibrinolysis was reduced (CLT, p<0.05). In contrast to findings in whole blood, the plasma fibrin clot became progressively more resistant towards tPA-induced fibrinolysis at both 4 h and 6 h (p<0.001).

Conclusions

Endotoxemia induced a hemostatic response with reduced primary but enhanced secondary hemostasis, enhanced early fibrinolysis and fibrinogen consumption followed by downregulation of fibrinolysis, with a discrepant fibrinolytic response in plasma and whole blood. The finding that blood cells are critically involved in the vasculo-fibrinolytic response to acute inflammation is important given that disturbances in the vascular system contribute significantly to morbidity and mortality in critically ill patients.

Predicting prothrombotic tendencies in sepsis using spatial clot growth dynamics

Inflammation in sepsis is associated with hypercoagulation that may lead to thrombosis and disseminated intravascular coagulation. Conventional diagnostic assays are poorly sensitive to procoagulant changes in sepsis. Objectives of the article is to study changes in hemostatic state of septic patients using spatial clot growth assay (currently being developed under the trademark of thrombodynamics) and to compare the sensitivity of this method with the sensitivity of conventional methods. Sixteen patients with hematological malignancies and sepsis were enrolled in the study. All patients had been surveyed for a month following the infection onset. Spatial clot growth assay monitors fibrin clot development in a nonstirred thin layer of platelet-free plasma activated by immobilized tissue factor. Clotting time tests, thromboelastography, D-dimer assays were also performed. Spatial clot growth revealed hypercoagulation in six patients. D-dimer levels increase (with vein thrombosis in one case) was subsequently observed in five of them. D-dimer levels did not increase when spatial clot growth was normal. At the next time point, after spatial clot growth assay showed hypercoagulation, the mean D-dimer concentration was significantly higher than after a normal analysis (457 versus 234 μg/l; P < 0.05); there was no such correlation for other assays. The remaining 10 patients had elevated D-dimer levels on the first day; this either decreased gradually or remained elevated. Spatial clot growth showed normalization in survivors and growing hypocoagulation in nonsurvivors. Measuring spatial clot growth dynamics has potential diagnostic utility for the evaluation of thrombotic risk.

Consecutive thrombelastography clot strength profiles in patients with severe sepsis and their association with 28-day mortality: a prospective study

PURPOSE

The aim of this study was to assess associations between consecutive thrombelastography (TEG) profiles and standard coagulation tests and disease severity and mortality in patients with severe sepsis.

MATERIALS AND METHODS

This was a prospective observational study of adults with severe sepsis admitted to the intensive care unit (ICU). Clinical scores/variables, infection, TEG, biochemistry, therapy, and overall mortality were recorded.

RESULTS

Fifty patients (60% men, median age 62 years, 28-day mortality 24%) were included. At admission, 22%, 48%, and 30% had a hypocoagulable, normocoagulable, and hypercoagulable TEG clot strength (maximum amplitude [MA]), respectively. Hypocoagulable patients had higher Sequential Organ Failure Assessment and disseminated intravascular coagulation scores compared with hypercoagulable patients and higher 28-day mortality compared with normocoagulable patients (all P < .05). Most patients (73%-91%) displayed a TEG MA comparable with the admission profile during the initial 4 ICU days or until death/discharge. Patients progressing to hypocoagulable MA had a high early mortality (80%) and hypocoagulable MA independently predicted 28-day mortality (adjusted odds ratio, 4.29 [95% confidence interval, 1.35-13.65], P = .014). In hypocoagulable and hypercoagulable patients, only fibrinogen (P = .041 and P < .001, respectively) contributed independently to clot strength, whereas both platelets (P < .001) and fibrinogen (P < .001) contributed independently to clot strength in normocoagulable patients.

CONCLUSIONS

The ICU admission TEG MA remained constant for several days in patients with severe sepsis and hypocoagulable MA independently predicted 28-day mortality.

Viscoelastic and aggregometric point-of-care testing in patients with septic shock - cross-links between inflammation and haemostasis

BACKGROUND

In the pathogenesis of sepsis, inflammation-induced changes in coagulation play a pivotal role.

METHODS

In total, 90 patients (30 patients with septic shock, 30 surgical patients following major abdominal surgery and 30 healthy volunteers) were enrolled. Blood samples from patients with septic shock were collected at the time of sepsis diagnosis as well as 24 h, 4 days, 7 days, 14 days and 28 days later. Samples from surgical patients with a post-surgical inflammatory response were collected three times (before surgery, immediately after surgery and 24 h after surgery) and once from healthy volunteers. Thromboelastometry (ROTEM (®) ), as well as whole blood impedance aggregometry (Multiplate(®) ) were performed. Additionally, plasma concentrations of interleukin-6 and tumour necrosis factor-alpha were measured using enzyme-linked immunosorbent assay kits.

RESULTS

Thromboelastometry lysis index was shown to be a reliable biomarker for septic shock. Furthermore, in septic patients with overt disseminated intravascular coagulation, thromboelastometry revealed signs indicating a hypocoagulable status, whereas patients without overt disseminated intravascular coagulation were found to be hypercoagulable. Platelet aggregation capability, as assessed by whole blood impedance aggregometry, was significantly reduced in septic patients with overt disseminated intravascular coagulation, whereas it was comparable with healthy volunteers and in septic patients without overt disseminated intravascular coagulation.

CONCLUSION

Viscoelastic and aggregometric point-of-care testing was shown to be potentially useful for bedside diagnosis of sepsis. Moreover, viscoelastic and aggregometric point-of-care testing was able to determine the phase of septic coagulopathy (hypercoagulability vs. hypocoagulability) and therefore identified patients at high risk for overt disseminated intravascular coagulation.

Early diagnostic markers of sepsis after oesophagectomy (including thromboelastography)

Background

Early diagnosis of sepsis and its differentiation from the noninfective SIRS is very important in order that treatment can be initiated in a timely and appropriate way. In this study we investigated standard haematological and biochemical parameters and thromboelastography (TEG) in patients who had undergone surgical resection of the oesophagus to find out if changes in any of these parameters could help in early differentiation between SIRS and sepsis development.

Methods

We enrolled 43 patients (aged 41–74 years) of whom 38 were evaluable. Blood samples were obtained on the morning of surgery and then at 24-hour intervals for the next 6 days. Samples were analysed for procalcitonin (PCT), C-reactive protein (CRP), interleukin-6 (IL- 6), aspartate transaminase (AST), alanine transaminase (ALT) , lactate, white blood count (WBC), D-dimers, antithrombin (AT), international normalised ratio (INR), activated partial thromboplastin time (APTT) and parameters of TEG.

Results

Significant differences between patients who developed sepsis during this period (9 patients) and SIRS were found in ALT on Day 1, in AST on Days 1–4, in PCT on Days 2–6; in CRP on Days 3–6; in IL-6 on Days 2–5; in leucocytes on Days 2, 3 and 6; and in D-dimers on Days 2 and 4. Significance values ranged from p < 0.0001 to p < 0.05.

Conclusions

Sequential measurements of ALT, AST, PCT and IL-6 during the early postoperative period can be used for early differentiation of sepsis and postoperative SIRS after oesophagectomy. Among the coagulation parameters measured, only D-dimer concentrations appeared to be helpful in this process. TEG does not seem to be a useful early predictor of sepsis development; however it can be used to differentiate sepsis and SIRS from Day 5 after surgery.

Persistent hypocoagulability in patients with septic shock predicts greater hospital mortality: impact of impaired thrombin generation

PURPOSE

Sepsis induces hypercoagulability, hypofibrinolysis, microthrombosis, and endothelial dysfunction leading to multiple organ failure. However, not all studies reported benefit from anticoagulation for patients with severe sepsis, and time courses of coagulation abnormalities in septic shock are poorly documented. Therefore, the aim of this prospective observational cohort study was to describe the coagulation profile of patients with septic shock and to determine whether alterations of the profile are associated with hospital mortality.

METHODS

Thirty-nine patients with septic shock on ICU admission were prospectively included in the study. From admission to day 7, analytical coagulation tests, thrombin generation (TG) assays, and thromboelastometric analyses were performed and tested for association with survival.

RESULTS

Patients with septic shock presented on admission prolongation of prothrombin time, activated partial thromboplastin time (aPTT), increased consumption of most procoagulant factors as well as both delay and deficit in TG, all compatible with a hypocoagulable state compared with reference values (P < 0.001). Time courses revealed a persistent hypocoagulability profile in non-survivors as compared with survivors. From multiple logistic regression, prolonged aPTT (P = 0.007) and persistence of TG deficit (P = 0.024) on day 3 were strong predictors of mortality, independently from disease severity scores, disseminated intravascular coagulation score, and standard coagulation tests on admission.

CONCLUSIONS

Patients with septic shock present with hypocoagulability at the time of ICU admission. Persistence of hypocoagulability assessed by prolonged aPTT and unresolving deficit in TG on day 3 after onset of septic shock is associated with greater hospital mortality.

A standardized technique for performing thromboelastography in rodents

Thromboelastography (TEG), used in liver transplant and cardiac surgery for nearly 50 years, has recently been applied to the trauma setting. Rodents are used widely for shock research, but are known to have differences in their coagulation system compared with humans. Consequently, the appropriate technique for performing TEG requires modification of the standard clinical protocol. Thromboelastography was performed with blood collected from the femoral artery of rodents, and technical modifications were tested to optimize results. Analysis of citrated whole blood using TEG revealed a more rapid onset of coagulation in rats compared with humans. The reference ranges of TEG parameters for Sprague-Dawley rats are detailed. Citrated native whole blood is the optimal TEG method in the assessment of coagulation in rodents. Investigators using TEG for research purposes should establish their own reference ranges to determine normal values for their target population.

Minimal effects of acute liver injury/acute liver failure on hemostasis as assessed by thromboelastography

BACKGROUND & AIMS

Patients with acute liver injury/failure (ALI/ALF) are assumed to have a bleeding diathesis on the basis of elevated INR; however, clinically significant bleeding is rare. We hypothesized that patients with ALI/ALF have normal hemostasis despite elevated INR.

METHODS

Fifty-one patients with ALI/ALF were studied prospectively using thromboelastography (TEG), which measures the dynamics and physical properties of clot formation in whole blood. ALI was defined as an INR ≥1.5 in a patient with no previous liver disease, and ALF as ALI with hepatic encephalopathy.

RESULTS

Thirty-seven of 51 patients (73%) had ALF and 22 patients (43%) underwent liver transplantation or died. Despite a mean INR of 3.4±1.7 (range 1.5-9.6), mean TEG parameters were normal, and 5 individual TEG parameters were normal in 32 (63%). Low maximum amplitude, the measure of ultimate clot strength, was confined to patients with platelet counts <126×10(9)/L. Maximum amplitude was higher in patients with ALF than ALI and correlated directly with venous ammonia concentrations and with increasing severity of liver injury assessed by elements of the systemic inflammatory response syndrome. All patients had markedly decreased procoagulant factor V and VII levels, which were proportional to decreases in anticoagulant proteins and inversely proportional to elevated factor VIII levels.

CONCLUSIONS

Despite elevated INR, most patients with ALI/ALF maintain normal hemostasis by TEG, the mechanisms of which include an increase in clot strength with increasing severity of liver injury, increased factor VIII levels, and a commensurate decline in pro- and anticoagulant proteins.

Characteristics of clinical sepsis reflected in a reliable and reproducible rodent sepsis model

BACKGROUND

Sepsis models are frequently based on induction of peritonitis, with cecal ligation and puncture reflecting the prototypical model. However, there is an ongoing discussion about the limitations of these models due to their variability in progression and outcome. Since standardization is a cornerstone of experimental models, we aimed to develop a reliable and reproducible procedure for induction of peritonitis.

MATERIALS AND METHODS

A human stool batch was processed for -80° storage. For induction of peritonitis in fluid-resuscitated rats, a defined volume of stool suspension from this batch was injected intraperitoneally. For characterization of the model, physiologic and inflammatory changes were evaluated after sepsis induction. Survival analyses with the same batch were repeated in four independent experiments over a time period of 16 mo.

RESULTS

The polymicrobial infection resulted in severe peritoneal inflammation with a systemic increase in cytokines. The mortality rate at 15 h was 29% and this was reproducible over a 16 mo time period. If antibiotic treatment was applied, a 50% survival was achieved. Laboratory markers indicated a progressive multi-organ dysfunction, while blood gas analysis showed respiratory compensation of a metabolic acidosis, and maintenance of PaO(2). Intravital microscopy of the liver revealed an impaired microcirculation. A decreased hemostatic potential was demonstrated by rotational thromboelastometry. Despite clinical recovery within 3 d, surviving animals showed laboratory and histologic signs of persisting inflammation even after 2 wk.

CONCLUSIONS

This model reflects many features of human sepsis. Application of an infectious focus that is both quantitatively and qualitatively defined assures high reproducibility. Moreover, the procedure is simple and can be easily standardized.

Minimal effects of acute liver injury/acute liver failure on hemostasis as assessed by thromboelastography

BACKGROUND & AIMS

Patients with acute liver injury/failure (ALI/ALF) are assumed to have a bleeding diathesis on the basis of elevated INR; however, clinically significant bleeding is rare. We hypothesized that patients with ALI/ALF have normal hemostasis despite elevated INR.

METHODS

Fifty-one patients with ALI/ALF were studied prospectively using thromboelastography (TEG), which measures the dynamics and physical properties of clot formation in whole blood. ALI was defined as an INR ≥1.5 in a patient with no previous liver disease, and ALF as ALI with hepatic encephalopathy.

RESULTS

Thirty-seven of 51 patients (73%) had ALF and 22 patients (43%) underwent liver transplantation or died. Despite a mean INR of 3.4±1.7 (range 1.5-9.6), mean TEG parameters were normal, and 5 individual TEG parameters were normal in 32 (63%). Low maximum amplitude, the measure of ultimate clot strength, was confined to patients with platelet counts <126×10(9)/L. Maximum amplitude was higher in patients with ALF than ALI and correlated directly with venous ammonia concentrations and with increasing severity of liver injury assessed by elements of the systemic inflammatory response syndrome. All patients had markedly decreased procoagulant factor V and VII levels, which were proportional to decreases in anticoagulant proteins and inversely proportional to elevated factor VIII levels.

CONCLUSIONS

Despite elevated INR, most patients with ALI/ALF maintain normal hemostasis by TEG, the mechanisms of which include an increase in clot strength with increasing severity of liver injury, increased factor VIII levels, and a commensurate decline in pro- and anticoagulant proteins.

Effects of nucleotides and nucleosides on coagulation

Nucleotides, including ADP, ATP and uridine triphosphate (UTP), are discharged profusely in the circulation during many pathological conditions including sepsis. Sepsis can cause hypotension and systemic activation of the coagulation and fibrinolytic systems in humans, which may cause disseminated intravascular coagulation. We investigated whether nucleotide-induced cardiovascular collapse as provoked by systemic infusion of adenosine, ADP, ATP, UTP and nitric oxide affected the haemostatic system as assessed by whole blood thromboelastography (TEG) analysis. Ten pigs received a randomized infusion of adenosine, ADP, ATP, UTP or nitric oxide until mean arterial pressure was reduced to approximately 40% of baseline simulating sepsis-induced hypotension. The effect of the infusions on the haemostatic system was evaluated by TEG, and endothelial release of tissue plasminogen activator and plasminogen activator inhibitor-1 was measured. In contrast to the other infused substrates, ADP caused a reduction in maximum amplitude (71.4 to 64.2; P < 0.05), and reduced the angle, representing the thrombus formation (75.6 to 66.4; P < 0.05), indicating hypocoagulation. Despite increases in t-PA release (2.1 to 2.7 ng/ml; P < 0.05) and reductions in plasminogen activator inhibitor (33.9 +/- 10.9-17.8 +/- 4.4 ng/ml; P < 0.05) no increased fibrinolysis was found when whole blood was evaluated by TEG. Circulating ADP induces hypocoagulation without signs of increased fibrinolysis as evaluated by TEG. The potential clinical significance of these findings should be investigated further because ADP discharged systemically may possibly contribute to the coagulopathy observed in severe sepsis.

Thromboelastometry (TEM) findings in disseminated intravascular coagulation in a pig model of endotoxinemia

Standard coagulation tests have a low specificity and sensitivity for diagnosing disseminated intravascular coagulation. The aim of this study was to determine whether whole blood thromboelastometry (TEM) detects lipopolysaccharide (LPS)-induced changes in coagulation. Blood samples from 10 pigs were drawn at baseline, before and at the end of LPS infusion and 2, 3, 4 and 5 h after the start of endotoxinemia. Simultaneous to TEM, standard coagulation tests and extended coagulation analysis including tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) were performed. Endotoxinemia resulted in a significant acceleration of the nonactivated TEM (NATEM) clotting time 2 h after the end of LPS infusion; in contrast, the changes in international normalized ratio and activated partial thromboplastin time suggested delayed initiation of coagulation. NATEM maximum clot firmness (MCF) and fibrin-based thromboelastometry test (FIBTEM)-MCF decreased significantly from baseline until the last time point (from 64.6 ± 7.8 and 35.1 ± 12.8 mm to 52.8 ± 4.6 and 21.4 ± 11.8 mm, respectively; P = 0.01 for both parameters). A sharp, transient increase of t-PA had no effect on maximum lysis in the NATEM test. PAI-1 increased significantly 3 h after the start of LPS infusion, paralleled by a decrease in maximum lysis. In conclusion, TEM was superior to standard coagulation tests in reflecting initial activation of coagulation during endotoxinemia. TEM further suggested consumption of coagulation substrate; at the same time, inhibition of plasminogen activation was accompanied by improved clot stability. Further investigations are necessary to establish the clinical relevance of these findings.

Comparison of thromboelastometry with procalcitonin, interleukin 6, and C-reactive protein as diagnostic tests for severe sepsis in critically ill adults

Introduction

Established biomarkers for the diagnosis of sepsis are procalcitonin, interleukin 6, and C-reactive protein. Although sepsis evokes changes of coagulation and fibrinolysis, it is unknown whether thromboelastometry can detect these alterations. We investigated whether thromboelastometry variables are suitable as biomarkers for severe sepsis in critically ill adults.

Methods

In the observational cohort study, blood samples were obtained from patients on the day of diagnosis of severe sepsis (n = 56) and from postoperative patients (n = 52), and clotting time, clot formation time, maximum clot firmness, alpha angle, and lysis index were measured with thromboelastometry. In addition, procalcitonin, interleukin 6, and C-reactive protein levels were determined. For comparison of biomarkers, receiver operating characteristic (ROC) curves were used, and the optimal cut-offs and odds ratios were calculated.

Results

In comparison with postoperative controls, patients with sepsis showed an increase in lysis index (97% ± 0.3 versus 92 ± 0.5; P < 0.001; mean and SEM) and procalcitonin (2.5 ng/ml ± 0.5 versus 30.6 ± 8.7; P < 0.001). Clot-formation time, alpha angle, maximum clot firmness, as well as interleukin 6 and C-reactive protein concentrations were not different between groups; clotting time was slightly prolonged. ROC analysis demonstrated an area under the curve (AUC) of 0.901 (CI 0.838 - 0.964) for the lysis index, and 0.756 (CI 0.666 - 0.846) for procalcitonin. The calculated cut-off for the lysis index was > 96.5%, resulting in a sensitivity of 84.2%, and a specificity of 94.2%, with an odds ratio of 85.3 (CI 21.7 - 334.5).

Conclusions

The thromboelastometry lysis index proved to be a more reliable biomarker of severe sepsis in critically ill adults than were procalcitonin, interleukin 6, and C-reactive protein. The results also demonstrate that early involvement of the hemostatic system is a common event in severe sepsis.

Coagulation status in coronary artery disease patients with type II diabetes mellitus compared with non-diabetic coronary artery disease patients using the PFA-100® and ROTEM®

Previous investigations in patients with coronary artery disease (CAD) revealed differences in thromboelastographic parameters indicating different states of coagulability. The aim of the present study was to investigate the coagulation status of patients with documented CAD and type II diabetes mellitus (DM) and non-diabetic patients with coronary artery disease with the PFA-100® and the ROTEM®. No differences were found in platelet function as measured with collagen/epinephrine (263.6 ± 70.6 s vs. 254.6 ± 65.3 s) and collagen/ADP cartridges (105.3 ± 63.2 s vs. 90.6 ± 47.3 s) in CAD patients with DM and CAD patients without DM. Measured with the EXTEM reagent of the ROTEM®, mean maximum clot elasticity (MCE) in patients with CAD and DM (233.6 ± 86.9) was significantly longer than in CAD patients without DM (186.7 ± 54.5), (p = 0.03). A similar result was seen using the INTEM reagent; patients with CAD and DM (234.4 ± 83.9) showed a higher value for MCE than CAD patients without DM (190.8 ± 57.8) which was of borderline significance (p = 0.053). Moreover, a weak trend for higher maximum clot firmness (MCF) was seen in CAD patients with DM compared with CAD patients without DM with the EXTEM reagent (68.1 ± 7.5 vs. 63.6 ± 8.6, p = 0.08) and the INTEM reagent (68.4 ± 7.2 vs. 64.1 ± 8.2, p = 0.09). The ROTEM® analysis indicates increased coagulability in patients with coronary artery disease and diabetes mellitus compared to non-diabetic CAD patients. Moreover, the ROTEM® device seems to be an appropriate and easy-to-use tool to describe the coagulation status in these patients groups.

Impaired microvascular perfusion in sepsis requires activated coagulation and P-selectin-mediated platelet adhesion in capillaries

PURPOSE

Impaired microvascular perfusion in sepsis is not treated effectively because its mechanism is unknown. Since inflammatory and coagulation pathways cross-activate, we tested if stoppage of blood flow in septic capillaries is due to oxidant-dependent adhesion of platelets in these microvessels.

METHODS

Sepsis was induced in wild type, eNOS(-/-), iNOS(-/-), and gp91phox(-/-) mice (n = 14-199) by injection of feces into the peritoneum. Platelet adhesion, fibrin deposition, and blood flow stoppage in capillaries of hindlimb skeletal muscle were assessed by intravital microscopy. Prophylactic treatments at the onset of sepsis were intravenous injection of platelet-depleting antibody, P-selectin blocking antibody, ascorbate, or antithrombin. Therapeutic treatments (delayed until 6 h) were injection of ascorbate or the glycoprotein IIb/IIIa inhibitor eptifibatide, or local superfusion of the muscle with NOS cofactor tetrahydrobiopterin or NO donor S-nitroso-N-acetylpenicillamine (SNAP).

RESULTS

Sepsis at 6-7 h markedly increased the number of stopped-flow capillaries and the occurrence of platelet adhesion and fibrin deposition in these capillaries. Platelet depletion, iNOS and gp91phox deficiencies, P-selectin blockade, antithrombin, or prophylactic ascorbate prevented, whereas delayed ascorbate, eptifibatide, tetrahydrobiopterin, or SNAP reversed, septic platelet adhesion and/or flow stoppage. The reversals by ascorbate and tetrahydrobiopterin were absent in eNOS(-/-) mice. Platelet adhesion predicted 90% of capillary flow stoppage.

CONCLUSION

Impaired perfusion and/or platelet adhesion in septic capillaries requires NADPH oxidase, iNOS, P-selectin, and activated coagulation, and is inhibited by intravenous administration of ascorbate and by local superfusion of tetrahydrobiopterin and NO. Reversal of flow stoppage by ascorbate and tetrahydrobiopterin may depend on local eNOS-derived NO which dislodges platelets from the capillary wall.

A novel thromboelastographic score to identify overt disseminated intravascular coagulation resulting in a hypocoagulable state

Thromboelastography (TEM) yields a multitude of data that are complicated to analyze. We evaluated its value in identification of global coagulopathy in overt disseminated intravascular coagulation (DIC). We studied 21 patients, each with International Society for Haemostasis and Thrombosis scores of 5 or more (compatible with overt DIC) and less than 5 (suggestive of nonovert DIC), who underwent whole blood nonadditive TEM. A TEM score based on the reaction and kappa times, alpha angle, and maximum amplitude was defined as the total number of TEM parameters deranged in the direction of hypocoagulability. The TEM score at a cutoff of 2 or more achieved sensitivity of 95.2%, specificity of 81.0%, and the highest receiver operating characteristic area under the curve of all parameters of 0.957 for identifying overt DIC. Individual TEM parameters correlated variably with conventional tests. Their combination into a cohesive TEM score possibly better captured the multiple hemostatic derangements occurring in DIC. The TEM score may bring objectivity to the analysis of TEM data.

Hypocoagulability, as evaluated by thrombelastography, at admission to the ICU is associated with increased 30-day mortality

Thrombelastography (TEG), a cell-based whole blood assay, may better reflect haemostatic competence than conventional coagulation assays and this was therefore evaluated including the clot forming parameters: R, angle and maximal amplitude in patients at ICU admission. This was a prospective, observational study of patients admitted to a general ICU at a tertiary care university hospital with an expected stay of more than 24 h. Blood samples for TEG and standard coagulation analysis were obtained at admission. The APACHE II and sequential organ failure assessment (SOFA) scores and 30-day mortality were recorded. At ICU admission, 106 patients (42%) showed hypocoagulability as evaluated by TEG and these patients had higher first day SOFA score (P < 0.0001) and higher 30-days (42 vs. 13%, P < 0.0001) mortality than patients presenting with a normal TEG. In 30-day survivors, admission platelet count (P = 0.05), angle (P < 0.001) and maximal amplitude (P = 0.001) were higher and R decreased (P = 0.0013) compared with nonsurvivors. Hypocoagulability at admission as evaluated by TEG was an independent risk factor for 30-day mortality [adjusted odds ratio (OR) 3.5; 95% confidence interval (CI) 1.7-7.1]. Hypocoagulability as evaluated by TEG was frequent at admission in general ICU patients and associated with a higher rate of ventilator treatment, higher rate of renal replacement therapy and a higher use of blood products. Hypocoagulability is an independent risk factor for 30-day mortality.