Prognostic values of the factor Xa-activated clotting time and endogenous thrombin potential in patients suspected of having disseminated intravascular coagulation

Enantiomeric separation of thiourea derivatives of naringenin on amylose and cellulose polymeric chromatographic chiral columns

Due to a great demand for amylose and cellulose polymeric chromatographic chiral columns, the enantiomeric separation of thiourea derivatives of naringenin was achieved on the different amylose (Chiralpak-IB) and cellulose chiral (Chiralcel-OJ and Chiralcel-OD-3R) columns with varied chromatographic conditions. The isocratic mobile phases used were ethanol and methanol, where ethanol/hexane and methanol/hexane were used as gradient mode and were prepared in volume/volume relation. The separation and resolution factors for all the enantiomers were in the range of 1.25 to 3.47 and 0.48 to 1.75, respectively. The enantiomeric resolution was obtained within 12 min making fast separation. The docking studies confirmed the chiral recognition mechanisms with binding affinities in the range of -4.7 to -5.7 kcal/mol. The reported compounds have good anticoagulant activities and may be used as anticoagulants in the future. Besides, chiral separation is fast and is useful for enantiomeric separation in any laboratory in the world.

Interaction between thrombin potential and age on early clinical outcome in patients hospitalized for COVID-19

Patients with Coronavirus Disease-2019 (COVID-19) have haemostatic dysfunction and are at higher risk of thrombotic complications. Although age is a major risk factor for outcome impairment in COVID-19, its impact on coagulative patterns here is still unclear. We investigated the association of Endogenous Thrombin Potential (ETP) with thrombotic and haemorrhagic events according to different ages in patients admitted for COVID-19. A total of 27 patients with COVID-19-related pneumonia, without need for intensive care unit admission or mechanical ventilation at hospital presentation, and 24 controls with non-COVID-19 pneumonia were prospectively included. ETP levels were measured on admission. Patients were evaluated for major adverse cardiovascular events (MACE: cardiovascular death, myocardial infarction, stroke, transient ischemic attack, venous thromboembolism) and bleeding complications [according to Bleeding Academic Research Consortium (BARC) definition] during in-hospital stay. COVID-19 patients had similar ETP levels compared to controls (AUC 93 ± 24% vs 99 ± 21%, p = 0.339). In the COVID-19 cohort, patients with in-hospital MACE showed lower ETP levels on admission vs those without (AUC 86 ± 14% vs 95 ± 27%, p = 0.041), whereas ETP values were comparable in patients with or without bleeding (AUC 82 ± 16% vs 95 ± 26%, p = 0.337). An interaction between age and ETP levels for both MACE and bleeding complications was observed, where a younger age was associated with an inverse relationship between ETP values and adverse event risk (p_int 0.018 for MACE and 0.050 for bleeding). Patients with COVID-19 have similar thrombin potential on admission compared to those with non-COVID-19 pneumonia. In younger COVID-19 patients, lower ETP levels were associated with a higher risk of both MACE and bleeding.

Role of a thrombin generation assay in the prediction of infection severity

Thrombin plays a central role in sepsis pathophysiology. The correlation of thrombin generation (TG) assays with infection severity and prognosis, and whether it can be used as a clinical tool, have been poorly explored and are the subjects of our research. We recruited 130 patients with systemic infection between 2016 and 2019. Patients were divided according to infection severity by using the sequential organ failure assessment (SOFA) and quickSOFA (qSOFA) scores. The hemostatic state was analyzed by Calibrated Automated Thrombogram. The primary end points were TG values and the secondary end point was in-hospital mortality. Patients with qSOFA ≥ 2 had a longer lag time (5.6 vs. 4.6 min) and time to peak (8 vs. 6.9 min) than those with lower scores (p = 0.014 and 0.01, respectively). SOFA ≥ 2 had a longer lag time (5.2 vs. 4.3 min), time to peak (7.5 vs. 6.7 min) and lower endogenous thrombin potential (ETP) (1834 vs. 2015 nM*min), p = 0.008, 0.019, and 0.048, respectively. Patients who died (11) had lower ETP (1648 vs. 1928 nM*min) and peak height (284 vs. 345 nM), p = 0.034 and 0.012, respectively. In conclusion TG assays may be a valuable tool in predicting infection severity and prognosis.

Disseminated intravascular coagulation: epidemiology, biomarkers, and management

Disseminated intravascular coagulation (DIC) is a systemic activation of the coagulation system, which results in microvascular thrombosis and, simultaneously, potentially life-threatening haemorrhage attributed to consumption of platelets and coagulation factors. Underlying conditions, e.g. infection, cancer, or obstetrical complications are responsible for the initiation and propagation of the DIC process. This review provides insights into the epidemiology of DIC and the current understanding of its pathophysiology. It details the use of diagnostic biomarkers, current diagnostic recommendations from international medical societies, and it provides an overview of emerging diagnostic and prognostic biomarkers. Last, it provides guidance on management. It is concluded that timely and accurate diagnosis of DIC and its underlying condition is essential for the prognosis. Treatment should primarily focus on the underlying cause of DIC and supportive treatment should be individualised according to the underlying aetiology, patient's symptoms and laboratory records.

Diminished coagulation capacity assessed by calibrated automated thrombography during acute Puumala hantavirus infection

: Coagulation abnormalities are associated with Puumala-virus-induced hemorrhagic fever with renal syndrome (PUUV-HFRS). We evaluated the coagulation capacity of plasma during acute PUUV-HFRS by measuring thrombin generation using calibrated automated thrombography (CAT). The study cohort comprised 27 prospectively collected, consecutive, hospital-treated patients with acute PUUV infection. Blood samples were drawn in the acute phase and at the control visit approximately 5 weeks later. To evaluate thrombin generation, the lag time of initiation, endogenous thrombin potential (ETP), and peak and time to peak thrombin concentration were assessed by CAT in platelet poor plasma without corn trypsin inhibitor. Plasma levels of D-dimer, fibrinogen and prothrombin fragments (F1 + 2) were also evaluated. When the acute phase was compared with the control phase, ETP was decreased (median 1154 nmol/l/min, range 67-1785 vs. median 1385 nmol/l/min, range 670-1970; P < 0.001), while the lag time was prolonged (median 3.8 min, range 2.1-7.7 vs. median 2.9 min, range 2.0-4.1; P < 0.001). Low ETP correlated with low peak thrombin concentration (r = 0.833, P < 0.001). Prolonged time to peak associated with the lag time (r = 0.78, P < 0.001). ETP was associated with thrombocytopenia (r = 0.472, P = 0.015) and weakly with fibrinogen level (r = 0.386, P = 0.047). The measured CAT parameters did not associate with D-dimer and F1 + 2 levels. Decreased ETP together with low peak and prolonged lag time indicate decreased plasma potential for thrombin generation in vitro. Together with low platelet count and enhanced fibrinolysis, this further refers to altered blood coagulation and increased propensity toward bleeding in acute PUUV-HFRS.

Role of plasma high mobility group box-1 in disseminated intravascular coagulation with leukemia

INTRODUCTION

High mobility group box 1(HMGB1) is a DNA-binding protein which can act as a proinflammatory cytokine when released by necrotic cells, monocytes or macrophages. It also plays a role in the coagulation activation and several tumors including leukemia. The objective of this study was to investigate the role of HMGB1 in the diagnosis of DIC with leukemia.

METHODS

89 subjects with leukemia in Wuhan Union Hospital were prospectively recruited. Among them, 83 cases were suspected of DIC, while the other 6 were the negative controls. Their clinical data, laboratory tests and plasma samples were collected or measured respectively. Accordingly, we made scores for these subjects by the Japanese Ministry of Health and Welfare (JMHW) criteria.

RESULTS

This study demonstrated that the plasma levels of HMGB1 were higher in the DIC group than non-DIC (115.16 ng/ml vs. 63.94 ng/ml, p=0.003). The similar results were achieved in infected or non-infected groups. And along with the increase of DIC scores, the levels of HMGB1 increased gradually (p=0.006). In addition, HMGB1 was an independent factor in the diagnosis of DIC with leukemia(p<0.05). The diagnostic sensitivity of HMGB1 was high (Se=90.32%), and there was a tendency of increased HMGB1 levels in the pre-DIC patients. Three of these six pre-DIC patients were diagnosed as DIC by the new revised scoring system which contained HMGB1. Finally, the HMGB1 levels were significantly higher in patients with organ failures (SOFA≥2) than those without (118.76 vs. 72.75, p=0.032).

CONCLUSION

The increased plasma levels of HMGB1 were related tightly to the diagnosis and severity of DIC in leukemia patients. Furthermore, the diagnostic sensitivity of HMGB1 was high. So HMGB1 in plasma is a helpful molecular marker, and can be added in the scoring system for the early diagnosis of DIC with leukemia.

Activation of the Intrinsic Coagulation Pathway in Patients With Chronic Urticaria

Purpose

Although coagulation activation has been reported in chronic urticaria, data pertaining to detailed changes in coagulation factors and global coagulation status are lacking. The current study evaluated global coagulation status in patients with chronic urticaria using thrombin generation assay (TGA) and the levels of individual coagulation factors.

Methods

Patients with chronic urticaria (n=57) and 20 healthy controls were enrolled. TGA was performed under stimulation with 2 concentrations of tissue factor (TF). Coagulation factors and conventional coagulation assays were also analyzed.

Results

Although patients with chronic urticaria showed prolonged activated partial thromboplastin time, prothrombin time did not differ significantly between patients and controls. In both 1 pM and 5 pM TF-stimulated TGA, peak thrombin and endogenous thrombin potential (ETP) levels were markedly decreased in patients with chronic urticaria. As expected, intrinsic coagulation factors (VIII, IX, and XII), as well as coagulation factors of the common pathway (II, V, and X), were consistently decreased. Additionally, D-dimer was significantly increased in patients as compared to controls. In multivariate regression analysis, the presence of chronic urticaria was the only significant independent contributor to the low ETP value.

Conclusions

Chronic urticaria is characterized by in vivo coagulation activation through the intrinsic coagulation pathway, which can be measured with sensitivity using TGA.

Association of the Plasma Platelet-Derived Microparticles to Platelet Count Ratio with Hospital Mortality and Disseminated Intravascular Coagulopathy in Critically Ill Patients

AIM

The role of platelet-derived microparticles (PDMPs) in the crosstalk between coagulopathy and inflammation in critically ill patients remains unclear. The aim of this cohort observational study was to investigate the associations between the PDMP levels and hospital mortality or disseminated intravascular coagulopathy (DIC).

METHODS

This study included 119 patients who were admitted to the ICU. The PDMP levels were measured using an enzyme-linked immunosorbent assay three times a week, for a total of 372 samples. We calculated the maximum (max) PDMP value, max PDMP/platelet (PDMP/Plts) ratio (converted to the PDMP levels per 10(4) platelets) and nadir platelet count during the ICU stay. Baseline patient data and scores, including the Japanese Association for Acute Medicine (JAAM) DIC score, were collected, and potential predictors were analyzed for possible associations with hospital mortality.

RESULTS

The max PDMP/Plts ratio was significantly different comparing the survivors (n=98: median, 2.54) and non-survivors (n=21: median 17.59; p＜0.001). There was a weak but statistically significant negative correlation between the max PDMP level and nadir platelet count (r=-0.332, p＜0.001). The max PDMP level and max PDMP/Plts ratio were higher in the DIC group (81.48 and 9.27, respectively) than in the non-DIC group (34.88 and 2.35, p=0.001 and p＜0.001, respectively). The max PDMP/Plts ratio was the only variable found to be independently associated with hospital mortality according to a multivariate logistic regression analysis.

CONCLUSIONS

PDMPs are involved in the development of DIC but are not related to hospital mortality. There is a good association between the PDMP/Plts ratio and hospital mortality and/or DIC in critically ill patients.

Ex vivo thrombin generation patterns in septic patients with and without disseminated intravascular coagulation

INTRODUCTION

The thrombin generation test (TGT) describes the ability of the plasma to generate thrombin. Its usefulness in septic patients has yet to be assessed.

METHODS

Patients admitted for severe sepsis in a medical intensive care unit were sampled for TGT on day 0, 3, 6, and 10. TGT data were compared to "classical" hemostastic tests and to outcome parameters, notably disseminated intravascular coagulation (DIC) according to International Society for Thrombosis and Hemostasis criteria as well as survival.

RESULTS

A total of 102 patients were recruited of whom 11 received therapeutic anticoagulation and showed profoundly-altered TGT parameters. In comparison to healthy subjects, the 67 septic patients without DIC exhibited longer Lag times, higher Rate Indices, no change in peak or amount of thrombin generated, although the return to baseline was prolonged. In the 24 DIC patients, Lag time and Rate Index did not differ from healthy subjects (Rate Index being significantly lower than in Sepsis patients). The decreases in peak and amount of thrombin generated were not significant. Return to baseline was prolonged comparatively to Sepsis patients. Due to a large overlap of TGT values between groups, the ability of TGT parameters to diagnose DIC or predict survival was respectively poor or absent.

CONCLUSION

The thrombin Generation Test displayed particular patterns in septic patients and in septic DIC patients. The wide overlap between patients in TGT values prevents the usefulness of this test in clinical practice.

Neutrophil Extracellular Traps Promote Thrombin Generation Through Platelet-Dependent and Platelet-Independent Mechanisms

Objective—

Activation of neutrophils by microbial or inflammatory stimuli results in the release of neutrophil extracellular traps (NETs) that are composed of DNA, histones, and antimicrobial proteins. In purified systems, cell-free DNA (CFDNA) activates the intrinsic pathway of coagulation, whereas histones promote thrombin generation through platelet-dependent mechanisms. However, the overall procoagulant effects of CFDNA/histone complexes as part of intact NETs are unknown. In this study, we examined the procoagulant potential of intact NETs released from activated neutrophils. We also determined the relative contribution of CFDNA and histones to thrombin generation in plasmas from patients with sepsis.

Approach and Results—

NETs released from phorbyl myristate–activated neutrophils enhance thrombin generation in platelet-poor plasma. This effect was DNA dependent (confirmed by DNase treatment) and occurred via the intrinsic pathway of coagulation (confirmed with coagulation factor XII– and coagulation factor XI–depleted plasma). In platelet-rich plasma treated with corn trypsin inhibitor, addition of phorbyl myristate–activated neutrophils increased thrombin generation and shortened the lag time in a toll-like receptor-2– and toll-like receptor-4–dependent mechanism. Addition of DNase further augmented thrombin generation, suggesting that dismantling of the NET scaffold increases histone-mediated, platelet-dependent thrombin generation. In platelet-poor plasma samples from patients with sepsis, we found a positive correlation between endogenous CFDNA and thrombin generation, and addition of DNase attenuated thrombin generation.

Conclusions—

These studies examine the procoagulant activities of CFDNA and histones in the context of NETs. Our studies also implicate a role for the intrinsic pathway of coagulation in sepsis pathogenesis.

High coagulation factor levels and low protein C levels contribute to enhanced thrombin generation in patients with diabetes who do not have macrovascular complications

AIMS

A prothrombotic state characterized by activation of the coagulation system has been implicated in the pathogenesis of vascular complications in diabetes mellitus. Recently, a thrombin generation assay was introduced as a laboratory assessment of global hemostatic potential. We used this thrombin generation assay to investigate global hemostatic potential in patients with diabetes who did not have macrovascular complications.

METHODS

This study was a prospective case-control study comparing 89 patients with diabetes with 49 healthy controls. The thrombin generation assay was conducted with the calibrated automated thrombogram using tissue factor with or without the addition of thrombomodulin, giving values for lag time, endogenous thrombin potential, and peak thrombin.

RESULTS

Patients with diabetes showed hypercoagulability, as detected by the thrombin generation assay, compared with healthy controls. Correspondingly, high levels of coagulation factors (II, V, VII, VIII, and X) and low levels of anticoagulant (protein C) were major contributing factors in this hypercoagulability. Interestingly, a high blood glucose level was correlated with shortened clotting time, reflecting the association between hyperglycemia and hypercoagulability. Patients who were taking statins or angiotensin receptor blockers showed decreased endogenous thrombin potential ratio and increased protein C levels, suggesting relative hypocoagulability.

CONCLUSIONS

Patients with diabetes showed hypercoagulability, high levels of coagulation factors, and low levels of protein C. Further study is required to investigate how this hemostatic potential may be used to guide physicians toward more effective management of hemostatic complications.

Contribution of procoagulant phospholipids, thrombomodulin activity and thrombin generation assays as prognostic factors in intensive care patients with septic and non-septic organ failure

BACKGROUND

Multiple organ dysfunction syndrome (MODS) observed in patients with sepsis and in nonseptic patients organ failure (OF) is associated with a high mortality rate. We investigated whether new coagulation assays [quantification of procoagulant phospholipids (PPL) activity, functional assays measuring the activity of thrombomodulin (TMa) or tissue factor (TFa) and thrombin generation using calibrated automated thrombography (CAT)] could constitute new tools to better understand the physiopathology of MODS and have any prognostic value.

METHODS

We measured TMa, TFa, PPL and CAT in 32 healthy controls, 24 patients with sepsis and 26 patients with non-septic OF. We compared these parameters with usual coagulation assays [prothrombin time, activated partial thromboplastin time, protein C (PC), protein S, D-Dimers (D-Di), soluble thrombomodulin (sTM)] and markers of inflammation (IL-6, CRP). Samples were collected within 24 h of the diagnosis.

RESULTS

TMa, TFa, PPL, the lag time and time to thrombin peak levels were increased in both groups of patients. For both groups D-Di, IL-6, CRP and endogenous thrombin potential (ETP) were higher in non-survivors than in survivors, while PC and PPL were lower in non-survivors than in survivors. TMa increase was more marked in non-survivors patients with OF, while the ratio TMa/sTM was low in non-survivors with sepsis. Received operating characteristic (ROC) curve analysis indicated that thrombin peak and ETP were the more powerful discriminating factors in patients with sepsis or non-septic OF, respectively.

CONCLUSIONS

PPL, TMa and CAT assays could represent promising tools to identify patients with increased risk of mortality in MODS and could procure insights into pathogenesis of MODS.

Plasma haemostatic potential of haemodialysis patients assessed by thrombin generation assay: hypercoagulability in patients with vascular access thrombosis

INTRODUCTION

Patients with end-stage renal disease (ESRD) on maintenance haemodialysis are predisposed to bleeding and thrombotic events. Recently thrombin generation assay (TGA) has been introduced as a laboratory assessment of global haemostatic potential. We investigated the global haemostatic potential assessed by TGA in ESRD patients on haemodialysis and patients who developed vascular access thrombosis.

MATERIALS AND METHODS

A total of 69 ESRD patients who underwent haemodialysis (58 stable patients and 11 vascular access thrombosis patients) were included and 33 healthy controls were included. TGA was performed on the calibrated automated thrombogram using tissue factor with/without addition of thrombomodulin or activated protein C, producing three parameters including lag time, endogenous thrombin potential (ETP) and peak thrombin.

RESULTS

Haemodialysis patients showed low ETP values measured by thrombin generation assay compared with the healthy controls. Interestingly, patients with vascular access thrombosis exhibited short PT and aPTT and increased resistance of coagulation inhibition to APC anticoagulant protein, reflecting hyper-coagulability. Haemodialysis patients who are taking anti-platelet agents showed decreased thrombin inhibition rate, representing antithrombotic effect of anti-platelet agents.

CONCLUSION

Whereas the haemodialysis patients showed hypo-coagulability, the patients with vascular access thrombosis exhibited hyper-coagulability. Further study is required to investigate how this haemostatic potential may be utilized to guide the physician to more effective management of haemostatic complication.

A comparative study on anticoagulant activities of three Chinese herbal medicines from the genus Panax and anticoagulant activities of ginsenosides Rg1 and Rg2

CONTEXT

Chemical compositions of three herbal plants from the family Araliaceae genus Panax [Panax ginseng C. A. Mey, P. quinquefolius L. and P. notoginseng (Burk.) F. H. Chen] are quite similar; however, their medicinal natures vary greatly. The reason for differences has been explained in traditional Chinese medicine theory and partially verified by modern pharmacological investigations, such as antiplatelet aggregation. Aside from platelet aggregation, a variety of plasma coagulation factors are also involved in blood coagulation. The anticoagulation profiles of three herbs have not been investigated.

OBJECTIVE

The current research compared the inhibitory effects of three herbal extracts from Panax spp. and the purified ginsenosides from P. ginseng on blood coagulation.

MATERIALS AND METHODS

Human plasma was mixed with the water extracts (0.05 and 0.1 mg/mL) from roots of P. ginseng, P. quinquefolius and P. notoginseng and ginsenosides Rg1 and Rg2 (0.05 and 0.1 mg/mL), the blood clotting time of activated partial thromboplastin, prothrombin and thrombin were measured by a biochemical analyzer.

RESULTS

The water extracts (0.05 mg/mL) of P. ginseng, P. quinquefolius and P. notoginseng could significantly extend blood clotting time as compared to the control group. Among three herbal medicines, 0.05 mg/mL of water extract from P. ginseng exhibited the strongest anticoagulation effects, followed by P. notoginseng, while P. quinquefolius presented the weakest effects. Both ginsenosides Rg1 and Rg2 could significantly extend blood clotting time in all three tests; ginsenoside Rg2 exhibited relative stronger anticoagulation effects as compared to ginsenoside Rg1.

DISCUSSION AND CONCLUSION

Among three herbs tested, P. ginseng as well as its active component ginsenoside Rg2 shows the strongest anticoagulation activity; current results indicate that P. ginseng and ginsenoside Rg2 have great potential to be an anticoagulation drug.

Influence of coagulation and anticoagulant factors on global coagulation assays in healthy adults

It remains unclear how coagulation and anticoagulant factors influence global coagulation assays such as prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin generation assay (TGA). We measured PT, aPTT, coagulation factor and protein levels, and TGA parameters (lag time, endogenous thrombin potential [ETP], and peak thrombin) in 252 apparently healthy adults. Vitamin K-dependent coagulation and anticoagulant factors were significantly correlated with blood lipids. PT was determined by factor (F) V and FVII; aPTT was dependent on antithrombin, protein C, FVIII, and FXII. Lag time was mainly determined by FVII, FXII, and protein S and peak thrombin by FVIII and FIX. Antithrombin (for ETP and lag time) and protein S (for lag time) contributed significantly to TGA inhibition. This knowledge about determinants of global coagulation assays may help interpret the results of coagulation assays and contribute to the future development of diagnostic tools. The synchronized plasma levels of vitamin K-dependent proteins with opposite functionalities may compensate a propensity to hyper- or hypocoagulability in a normal population.

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.

A laboratory evaluation into the short activated partial thromboplastin time

Although short activated partial thromboplastin times (APTTs) are generally considered to be laboratory artefacts of problematic blood collections, there is mounting evidence that in some cases a short APTT may reflect a hypercoagulable state, potentially associated with increased thrombotic risk and adverse cardiovascular events. We prospectively evaluated the phenomenon of short APTTs in 113 consecutive samples compared with an equal number of age and sex-matched normal APTT samples. We found a significant difference in various test parameters including prothrombin time (PT), Factor (F) V, FVIII, FXI, FXII, von Willebrand factor (VWF) antigen and collagen-binding activity, and in the level of procoagulant phospholipids, as assessed using a novel assay procedure (XACT). Interestingly, there was a significant negative association for fibrinogen, and although elevated, there was no significant association for FIX. On the basis of identified consecutive samples having multiple low APTTs on several sequential days, a proportion of laboratory-defined short APTTs appear to represent in-vivo hypercoagulability. In conclusion, plasma from patients presenting with short APTTs is reflective of a complex hypercoagulant milieu that could feasibly contribute to thrombotic risk, and 20% or more of laboratory definable short APTTs appear to reflect in-vivo phenomenon.

Hemostasis during low molecular weight heparin anticoagulation for continuous venovenous hemofiltration: a randomized cross-over trial comparing two hemofiltration rates

Introduction

Renal insufficiency increases the half-life of low molecular weight heparins (LMWHs). Whether continuous venovenous hemofiltration (CVVH) removes LMWHs is unsettled. We studied hemostasis during nadroparin anticoagulation for CVVH, and explored the implication of the endogenous thrombin potential (ETP).

Methods

This cross-over study, performed in a 20-bed teaching hospital ICU, randomized non-surgical patients with acute kidney injury requiring nadroparin for CVVH to compare hemostasis between two doses of CVVH: filtrate flow was initiated at 4 L/h and converted to 2 L/h after 60 min in group 1, and vice versa in group 2. Patients received nadroparin 2850 IU i.v., followed by 380 IU/h continuously in the extracorporeal circuit. After baseline sampling, ultrafiltrate, arterial (art) and postfilter (PF) blood was taken for hemostatic markers after 1 h, and 15 min, 6 h, 12 h and 24 h after converting filtrate flow. We compared randomized groups, and 'early circuit clotting' to 'normal circuit life' groups.

Results

Fourteen patients were randomized, seven to each group. Despite randomization, group 1 had higher SOFA scores (median 14 (IQR 11-15) versus 9 (IQR 5-9), p = 0.004). Anti-Xa _art activity peaked upon nadroparin bolus and declined thereafter (p = 0.05). Anti-Xa _PF did not change in time. Anti-Xa activity was not detected in ultrafiltrate. Medians of all anti-Xa samples were lower in group 1 (anti-Xa _art 0.19 (0.12-0.37) vs. 0.31 (0.23-0.52), p = 0.02; anti-Xa _PF 0.34 (0.25-0.44) vs. 0.51 (0.41-0.76), p = 0.005). After a steep decline, arterial ETP_AUC tended to increase (p = 0.06), opposite to anti-Xa, while postfilter ETP_AUC increased (p = 0.001). Median circuit life was 24.5 h (IQR 12-37 h). Patients with 'short circuit life' had longer baseline prothrombin time (PTT), activated thromboplastin time (aPTT), lower ETP, higher thrombin-antithrombin complexes (TAT) and higher SOFA scores; during CVVH, anti-Xa, and platelets were lower; PTT, aPTT, TAT and D-dimers were longer/higher and ETP was slower and depressed.

Conclusions

We found no accumulation and no removal of LMWH activity during CVVH. However, we found that early circuit clotting was associated with more severe organ failure, prior systemic thrombin generation with consumptive coagulopathy, heparin resistance and elevated extracorporeal thrombin generation. ETP integrates these complex effects on the capacity to form thrombin.

Trial registration

Clinicaltrials.gov ID NCT00965328