Stability over time of immature platelet fraction and comparison between EDTA and citrated whole blood samples.

BACKGROUND: Immature platelets (IP) are the youngest circulating platelets, released from megakaryocytes, and demonstrating increased dimensions, significant RNA content, and enhanced activity. Immature platelet research focuses on a differential diagnostic help in patients with thrombocytopenia. The objectives of this study were to compare the variability of IP in citrate and EDTA samples, and to determine stability over time. METHODS: Fifty-six patients were included for comparison between EDTA and citrate whole blood sample collection. Among the patients, 28 had thrombocytopenia (platelet count < 150G/L). Platelet measurement impedancemetry and fluorimetry were performed with Sysmex XN-9000. The immature platelet fraction (IPF) and absolute immature platelet count (A-IPC) were determined with a fluorescent method. RESULTS: The mean value of platelet count with fluorescence was, in EDTA sample, 215 ± 171 and, in citrate sample, 153 ± 118 G/L. No significant difference was observed between IPF between EDTA and citrate (7.74 ± 6.68% vs. 8.45 ± 7.37%, p = 0.69), respectively. With the Bland-Altman analysis, the mean difference in the EDTA sample, between 1 and 24 h, was 8.06 ± 6.96% and 8.73 ± 7.12% for IPF, whereas in the citrate sample, between 1 and 6 h, it was 8.60 ± 7.29% and 7.54 ± 6.97%, for IPF. Comparing 1 h EDTA sample with 6 h citrate sample, the variance ratio was 0.974 (95% CI: 0.864-1.084) in IPF. CONCLUSIONS: We confirmed the potential to conduct IP measurements up to 24 h in the EDTA sample and IPF measurements in the citrate sample for up to 6 h. These results may be useful for the use of IPF, which is a promising parameter whose interest in clinical practice and standardization is not yet well defined.

Point-of-Care Viscoelastic Hemostatic Assays in Cardiac Surgery Patients: Comparison of Thromboelastography 6S, Thromboelastometry Sigma, and Quantra.

OBJECTIVES: Viscoelastic tests allow a reduction in blood product transfusion. Three modern devices are currently available (rotational thromboelastometry [ROTEM] sigma, thromboelastography [TEG] 6S, and Quantra). No study has compared the performances of these 3 devices simultaneously. DESIGN: An observational, nonrandomized cohort study. SETTING: A single-center of cardiac surgery in a university hospital. PARTICIPANTS: A total of 30 consecutive measurements from at least 10 adult patients presenting significant bleeding in the intensive care unit after cardiac surgery INTERVENTION: Viscoelastic tests using ROTEM sigma, TEG 6S, and Quantra were performed concomitantly with conventional coagulation measurements MEASUREMENTS AND MAIN RESULTS: The authors included 16 patients with 31 blood samples. After the exclusion of missing values, 27 samples were analyzed. Correlation with platelet count was as follows: ROTEM, r = 0.84 [0.66-0.93], p < 0.0001; Quantra, r = 0.83 [0.64-0.92], p < 0.0001; TEG 6S, r = 0.64 [0.29-0.83], p = 0.001. Correlation with fibrinogen (Clauss assay) was as follows: ROTEM, r = 0.85 [0.68-0.93], p < 0.0001; Quantra, r = 0.88 [0.74-0.95], p < 0.0001; TEG 6S, r = 0.79 [0.55-0.91], p < 0.0001. No difference was observed for the detection of residual circulating heparin (anti-Xa activity >0.1), with 87% of correct identification for Quantra and 80% for both ROTEM and TEG 6S (p = 0.3). Time to first results after the beginning of the test was shorter for Quantra than ROTEM and TEG 6S (136 [126-152] seconds v 205 [176-221] seconds, p = 0.003 and v 450 [372-516] seconds, p < 0.0001 respectively). CONCLUSION: ROTEM sigma, TEG 6S, and Quantra performed similarly for exploring platelet count or residual circulating heparin. Thromboelastography 6S presented a weaker correlation with fibrinogen Clauss.

First observation of inhibitor development against efmoroctocog alfa in France.

In patients with severe haemophilia receiving clotting factor concentrates, the risk of immunisation against their usual treatment is still patent and feared. New haemophilia drug treatments with an extended half-life have become available over the past few years. The risk of inhibitor development to these new treatments is unclear. We report the case of a 51-year-old man with severe haemophilia A, who was previously treated with no history of inhibitor development. Soon after a switch in his treatment to efmoroctocog alfa he developed an inhibitor against this recombinant Fc fusion extended half-life FVIII (rFc-FVIII) product. The patient was on an on-demand treatment regimen and was treated for mucosal bleeding. The inhibitor was characterised as type I, with classical epitope mapping. The spontaneous evolution of this inhibitor was favourable, but an anamnestic response led to a switch in his treatment to emicizumab.

Anti-Xa Oral Anticoagulant Plasma Concentration Assay in Real Life: Rivaroxaban and Apixaban Quantification in Emergency With LMWH Calibrator.

BACKGROUND: Oral anti-Xa inhibitors have demonstrated noninferiority to vitamin K antagonists (VKAs) for the prevention of stroke in patients with atrial fibrillation and recurrent venous thromboembolism. They are associated with a decrease in major bleeding. In contrast with VKA, no coagulation monitoring is required. However, in clinical practice, determination of drug concentration is sometimes necessary. OBJECTIVE: The objective of this study was to evaluate a low-molecular-weight heparin (LMWH) calibrated anti-Xa assay for the quantification of rivaroxaban and apixaban plasma concentration in emergency. METHODS: The anti-Xa plasma concentration of rivaroxaban and apixaban were measured in emergency in 210 patients using STA anti-Xa liquid assay. For each plasma concentration <150 ng/mL of rivaroxaban or apixaban, an anti-Xa assay calibrated with LMWH was performed. RESULTS: We demonstrated a significant correlation between LMWH anti-Xa activity and rivaroxaban ( R2 = 0.947) or apixaban ( R2 = 0.959) concentration and a significant correlation between rivaroxaban and apixaban plasma concentration ( R2 = 0.972). A LMWH anti-Xa activity <0.50 IU/mL could exclude a plasma concentration of rivaroxaban and apixaban >30 ng/mL and indicate the feasibility of invasive procedure. Conclusion and Relevance: In the absence of a specific test, LMWH-calibrated anti-Xa assay could be used to determine the presence and evaluate the plasma concentration of oral anti-Xa inhibitors. However, these initial findings require confirmation using other chromogenic calibrated oral anti-Xa assays.

Thrombin generation profile in non-thrombotic factor V Leiden carriers.

Factor V Leiden (FVL) mutation is the most common genetic risk factor for venous thromboembolism. In families with a history of thrombosis, FVL can be present in 18%. Thrombin generation test is commonly used as an evaluation tool of thrombotic risk. The objective of this study was to evaluate the thrombogenic potential of FVL in asymptomatic carriers and in patients with personal or familial history of thrombosis. This was a retrospective single center study including 160 patients. Among them, 43 had personal history of thrombosis and 117 had familial history of thrombosis. Thrombin generation (TG) was realized in frozen platelet poor plasma with 1 pM of tissue factor and 4 µM of phospholipid. FVL mutation was associated with a global increase of TG. No difference was observed between patients with provoked thrombosis and patients with first-degree familial history of thrombosis (endogenous thrombin potential (ETP): 1501.0 ± 316.4 nM min and thrombin peak: 253.4 ± 71.5 nM vs. 1520.4 ± 283.8 nM min and 268.6 ± 68.0 nM). An increase of TG was observed in patients with unprovoked thrombosis (n = 23) and in patients with provoked thrombosis (n = 20) (ETP: 1819.5 ± 319.8 nM min and peak: 332.3 ± 55.8 nM). In the unprovoked thrombosis group, patients with a pulmonary embolism had a higher ETP than patients with deep vein thrombosis (DVT) (2036 ± 343 nM min vs. 1707 ± 261 nM min). With a predictive score formula (s = 0.1315 × Age + 0.0105 × ETP) with a threshold of 22.1 as risk to develop an unprovoked thrombosis among patients with second-degree familial history. The results of our analysis suggest that measurement of thrombin generation in patients with FVL mutation may identify subjects with an increased risk of unprovoked thrombosis. Further studies are needed to examine the usefulness of predicting thrombotic presentation in asymptomatic carriers.

Is citrate theophylline adenosine dipyridamole (CTAD) better than citrate to survey unfractionated heparin treatment? Has delayed centrifugation a real impact on this survey?

Unfractionated heparin (UFH) is the main anticoagulant used in intensive care unit. The anticoagulant effect is monitored by activated partial thrombin time (aPTT) and anti-Xa activity (anti-Xa) measurement. However, delayed centrifugation induces platelet factor 4 (PF4) release and anti-Xa decrease. Several studies have concluded that aPTT and anti-Xa measurement should be performed within 2 h in citrated anticoagulant but may be delayed longer in Citrate Theophylline Adenosine and Dypiridamol (CTAD) anticoagulant. The objective of this study was to compare the stability of both aPTT and anti-Xa in citrate and CTAD samples, and to determine the effect of delayed centrifugation on both aPTT, anti-Xa results, and PF4 release in citrate samples only. aPTT and anti-Xa were measured in citrate and CTAD anticoagulant samples from 93 patients. Delayed centrifugation was performed in citrate samples from 31 additional patients, with hourly aPTT and anti-Xa measurement from 1 to 6 h. In 14 of these last patients, PF4 release was also evaluated with Human CXCL4/PF4 Quantikine ELISA Kit. We observed a significant correlation between citrate and CTAD anticoagulant for aPTT (r2 = 0.94) and anti-Xa (r2 = 0.95). With Bland-Altman correlation, a minor bias was observed for anti-Xa (- 0.025 ± 0.041). Delayed centrifugation in citrated anticoagulant showed an excellent concordance from 1 to 4 h for aPTT (- 4.0 ± 5.3 s) and anti-Xa (1.10-9 ± 0.058 UI/ml) measurements. Moreover, PF4 release was not different between 1 h (31.5 ± 14.7 ng/ml) and 4 h (33.8 ± 11.8 ng/ml). We have demonstrated that anti-Xa measurement for unfractionated heparin should be done 4 h in citrated plasma and that CTAD was not better than citrate. However, these initial findings require confirmation using other aPTT and calibrated anti-Xa assays.

Thrombin generation test as a marker for high risk venous thrombosis pregnancies.

Pregnancy is a well-established risk factor for venous thromboembolism and is associated with a state of hypercoagulability. The use of sensitive and specific biological markers to predict risk factors for thrombosis is essential during pregnancy. Our objective was to investigate the usefulness of thrombin generation test (TGT) as a marker to predict the risk of thrombosis in high risk venous thrombosis (HRVT) pregnancies compared to normal pregnancies. This retrospective study enrolled 134 women with HRVT pregnancies, 78 of whom had monozygotic, spontaneous and untreated pregnancies and formed the study group. The control group comprised 106 women with normal pregnancies. Routine assessment of coagulation activation markers: fibrinogen, D-dimer, prothrombin fragments 1 + 2 (F1 + 2), thrombin-antithrombin complexes (TAT) and fibrin monomer complexes (FMC) was performed every 5 weeks in the study group to detect a possible pathological state of hypercoagulability. TGT was performed using platelet-free plasma, 1 and 5 pM tissue factor (TF), supplemented by phospholipids (PL) ± thrombomodulin. Fibrinogen, D-dimer, F1 + 2, and TAT, but not FMC, increased significantly throughout pregnancy in both groups but no difference was shown between the groups. TGT showed an early increase in thrombin generation in both groups, which stabilized during the second month of pregnancy. No correlation was demonstrated between thrombin generation parameters and coagulation activation markers. Based on our results, TGT did not prove conclusive as a marker to predict the risk of thrombosis in HRVT pregnancies. Finding a sensitive and specific biological marker to predict thrombosis risk requires further investigation.

Thrombotic thrombocytopenic purpura misdiagnosed as autoimmune cytopenia: Causes of diagnostic errors and consequence on outcome. Experience of the French thrombotic microangiopathies reference centre.

Thrombotic thrombocytopenic purpura (TTP) has a devastating prognosis without adapted management. Sources of misdiagnosis need to be identified to avoid delayed treatment. We studied 84 patients with a final diagnosis of severe (<10%) acquired ADAMTS13 deficiency-associated TTP from our National database that included 423 patients, who had an initial misdiagnosis (20% of all TTP). Main diagnostic errors were attributed to autoimmune thrombocytopenia, associated (51%) or not (37%) with autoimmune hemolytic anemia. At admission, misdiagnosed patients were more frequently females (P = .034) with a history of autoimmune disorder (P = .017) and had organ involvement in 67% of cases; they had more frequently antinuclear antibodies (P = .035), a low/undetectable schistocyte count (P = .001), a less profound anemia (P = .008), and a positive direct antiglobulin test (DAT) (P = .008). In multivariate analysis, female gender (P = .022), hemoglobin level (P = .028), a positive DAT (P = .004), and a low schistocytes count on diagnosis (P < .001) were retained as risk factors of misdiagnosis. Platelet count recovery was significantly longer in the misdiagnosed group (P = .041) without consequence on mortality, exacerbation and relapse. However, patients in the misdiagnosed group had a less severe disease than those in the accurately diagnosed group, as evidenced by less organ involvement at TTP diagnosis (P = .006). TTP is frequently misdiagnosed with autoimmune cytopenias. A low schistocyte count and a positive DAT should not systematically rule out TTP, especially when associated with organ failure.

Role of M2-like macrophage recruitment during angiogenic growth factor therapy.

Therapeutic angiogenesis has yet to fulfill its promise for the clinical treatment of ischemic diseases. Given the impact of macrophages during pathophysiological angiogenesis, we asked whether macrophages may similarly modulate vascular responses to targeted angiogenic therapies. Mouse matrigel plug assay and rat myocardial infarction (MI) model were used to assess angiogenic therapy with either VEGF-A or FGF-2 with HGF (F+H) delivered locally via albumin-alginate microcapsules. The infiltration of classical M1-type and alternative M2-like macrophages was assessed. Clodronate was used to prevent macrophage recruitment, and the VEGFR2 blocking antibody, DC101, to prevent VEGF-A signaling. At 3 weeks after matrigel implantation, the combination therapy (F+H) led to increased total, and specifically M2-like, macrophage infiltration versus control and VEGF-A plugs, correlating with the angiogenic response. In contrast, VEGF-A preferential recruited M1-type macrophages. In agreement with a direct role of M2-like macrophages in F+H-induced vessel growth, clodronate radically decreased angiogenesis. Further, DC101 reduced F+H-induced angiogenesis, without altering macrophage infiltration, revealing macrophage-derived VEGF-A as a crucial determinant of tissue responsiveness. Similarly, increased cardiac M2-like macrophage infiltration was found following F+H therapy post-MI, with strong correlation between macrophage levels and angiogenic and arteriogenic responses. In conclusion, M2-like macrophages play a decisive role, linked to VEGF-A production, in regulation of tissue responsiveness to angiogenic therapies including the combination of F+H. Our data suggest that future attempts at therapeutic revascularization in ischemic patients might benefit from coupling targeted growth factor delivery with either direct or indirect approaches to recruit pro-angiogenic macrophages in order to maximize therapeutic angiogenic/arteriogenic responses.

[Evaluation of a diagnostic test for heparin-induced thrombocytopenia: validation of a delayed test time]. / Évaluation d'un test d'orientation diagnostique de thrombopénie induite à l'héparine : validation d'un délai différé de réalisation du test.

Heparin-induced thrombocytopenia (HIT) is a rare, iatrogenic condition, characterized by its potential severity and diagnostic difficulties. The diagnosis is based on a set of arguments allowing the calculation of a pre-test score pointing to HIT. There are rapid diagnostic tests for suspected HIT. Among these, the STic Expert® HIT has a good sensitivity to detect HIT. However, it must be performed within 2 hours after sampling. The aim of this study was to evaluate a delayed STic Expert® HIT test at 8 hours and in frozen plasma. Thirty-six patients were prospectively included for HIT testing between April 01, 2018, and July 1, 2022, at the University Rouen Hospital. For any request for HIT testing, an analysis by STic Expert® HIT was performed within 2 hours and 8 hours post-sampling. Any positive result was confirmed by a functional test, platelet aggregation with heparin, release of 14C-serotonin assay (SRA), and immunological assay by a research for anti-platelet factor 4 IgG antibodies. Twenty-three patients had a STic Expert® HIT. Sixteen presented platelet aggregations in the presence of heparin and had a positive anti-PF4 test, 17 had a positive SRA. Six patients had no HIT. For the test performed within 2 hours of collection, the Se = 100%, Sp = 68.42%, PPV = 73.91%, and NPV = 100%. The X2 = 18.21 with p < 0.001. For the test performed at 8 hours post sampling, the Se = 100%, Sp = 68.42%, PPV = 73.91% and NPV = 100%. The X2 = 18.21 with p < 0.001. In conclusion, we have demonstrated that the STic Expert® can be used to perform an HIT diagnostic test 8 hours after sampling and on thawed plasma. However, this study needs to be confirmed on a larger number of samples.

Obstetrical complications in hereditary fibrinogen disorders: the Fibrinogest study.

BACKGROUND: Women with hereditary fibrinogen disorders (HFDs) seem to be at an increased risk of adverse obstetrical outcomes, but epidemiologic data are limited. OBJECTIVES: We aimed to determine the prevalence of pregnancy complications; the modalities and management of delivery; and the postpartum events in women with hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia. METHODS: We conducted a retrospective and prospective multicentric international study. RESULTS: A total of 425 pregnancies were investigated from 159 women (49, 95, and 15 cases of hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia, respectively). Overall, only 55 (12.9%) pregnancies resulted in an early miscarriage, 3 (0.7%) resulted in a late miscarriage, and 4 (0.9%) resulted in an intrauterine fetal death. The prevalence of live birth was similar among the types of HFDs (P = .31). Obstetrical complications were observed in 54 (17.3%) live birth pregnancies, including vaginal bleeding (14, 4.4%), retroplacental hematoma (13, 4.1%), and thrombosis (4, 1.3%). Most deliveries were spontaneous (218, 74.1%) with a vaginal noninstrumental delivery (195, 63.3%). A neuraxial anesthesia was performed in 116 (40.4%) pregnancies, whereas general or no anesthesia was performed in 71 (16.6%) and 129 (44.9%) pregnancies, respectively. A fibrinogen infusion was administered in 28 (8.9%) deliveries. Postpartum hemorrhages were observed in 62 (19.9%) pregnancies. Postpartum venous thrombotic events occurred in 5 (1.6%) pregnancies. Women with hypofibrinogenemia were at an increased risk of bleeding during the pregnancy (P = .04). CONCLUSION: Compared with European epidemiologic data, we did not observe a greater frequency of miscarriage, while retroplacental hematoma, postpartum hemorrhage, and thrombosis were more frequent. Delivery was often performed without locoregional anesthesia. Our findings highlight the urgent need for guidance on the management of pregnancy in HFDs.

Management of patients with inherited bleeding disorders in oral surgery: A 13-year experience.

INTRODUCTION: The management of patients with inherited bleeding disorders in oral surgery requires the systematic evaluation of bleeding risk and the setting up of an adequate treatment protocol by the referring haematologist, defining a replacement therapy and a recommended length of hospital stay. The purpose of this study was to determine the bleeding risk associated with oral surgery for each type of inherited bleeding disorder and to evaluate the efficacy of the treatment protocols set up in our tertiary care center. MATERIALS AND METHODS: We included all patients with an inherited bleeding disorder, managed in our oral and maxillofacial surgery department with a treatment protocol set up by our local Haemophilia Treatment Centre for an oral surgical procedure. RESULTS: Between January 2006 and December 2018, 295 treatment protocols were set up for the management of patients with haemorrhagic risk in oral surgical procedures. Of these, 203 were scheduled to take place in our department. A total of 180 oral surgical procedures for 147 patients were included. The incidence of bleeding complications in our study was 4.44% (8 out of 180) with a significantly higher risk in patients with haemophilia, the mean time to onset of bleeding was 11 days. DISCUSSION: The use of a treatment protocol for the management of patients with inherited bleeding disorders in oral surgery seems effective. Our rate of bleeding complications was comparable to data in the literature, and often lower.

Factor XII deficiency evaluated by thrombin generation assay.

INTRODUCTION: Coagulation factor XII (FXII) plays a role in thrombin generation, fibrinolysis, inflammation, angiogenesis, chemotaxis and diapedesis. FXII deficiency is not associated with bleeding risk unlike other coagulation factors. MATERIALS/METHODS: We investigated thrombin generation assay (TGA) profile modification in FXII deficiency and the correlation with TGA and deficiency severity. TGA was performed in platelet poor plasma (PPP) with tissue factor (1 pmol/L) and phospholipid (4 µmol/L) standardized concentration. Thrombin generation profiles were compared in 54 patients with FXII deficiency, 25 healthy controls and 23 patients with hemophilia A (factor VIII (FVIII) deficiency. Patients with FXII deficiency were classified in three groups based on FXII activity (30-50%, 10-29%, <10%). FVIII deficiency was included as a bleeding control group. RESULTS: As expected, we found a correlation between FXII deficiency and activated partial thromboplastin time (aPTT). A decrease of thrombin generation was observed in healthy controls and all FXII deficiency groups. A decrease of endogenous thrombin potential (ETP), peak and velocity was observed in patients with FVIII deficiency compared to FXII deficiency. A decrease of thrombin generation was noted in patients with FXII deficiency and bleeding history compared to patients with FXII deficiency and thrombosis history. CONCLUSION: In this study, thrombin generation profiles were not sensitive to FXII deficiency. TGA could distinguish bleeding and thrombotic tendency in FXII deficiency. Our results should therefore be considered as exploratory and deserve confirmation.

Evaluation of thrombin generation assay in factor XI deficiency.

INTRODUCTION: Factor XI (FXI) deficiency is characterized by a lack of correlation between FXI plasma levels and the occurrence of hemorrhagic events. The main objective of our study was to determine whether thrombin generation assay (TGA) could be used to assess the hemorrhagic phenotype of patients with FXI deficiency. MATERIAL AND METHODS: All patients had confirmed laboratory measurement of FXI < 50% in two plasma samples. Relevant bleeding history was evaluated by a senior physician. TGA was performed with Calibrated Automated Thrombography, in platelet poor plasma, from patients and healthy controls. The assay was performed with PPP low reagent (1 pM of human tissue factor). RESULTS: Seventy-six patients with FXI deficiency were included between 2011 and 2020. Among them, eight patients had severe deficiency (FXI < 15%). Mean age was 34 years [range: 9-77]. Endogenous thrombin potential (ETP) was significantly lower in patients with FXI deficiency and bleeding (573 nM·min [225-1214]) or no bleeding (732 nM·min [222-1435]), compared to healthy controls (1184 nM·min [933-1518]). No difference was observed for ETP and peak between patients with FXI deficiency and bleeding and patients with FXI deficiency and no bleeding. No difference was observed for ETP (923 nM·min [377-1497] vs 1063 nM·min [252-2529]), peak (82 nM [28-154] vs 131 nM [20-330]) or velocity (13.7 nM/min [3.6-29.6] vs 26.5 nM/min [2.5-90]) in women with (n = 4) and without history (n = 17) of post-partum bleeding. No difference of thrombin generation was observed in pregnant women with FXI deficiency (ETP: 1395 nM·min [351-2529]; peak: 154 nM [26-330]; velocity: 29.6 nM/min [4.1-90.0]), compared to healthy controls and a control group of healthy pregnant women. CONCLUSION: In conclusion, under our experimental condition, a non-significant decrease of thrombin generation was observed in plasma samples of patients with FXI deficiency and bleeding. Our results suggest an increase of coagulation parameters during pregnancy in women with FXI deficiency. A larger sample size or other experimental conditions are required to evaluate the use of TGA in FXI deficiency.

[Theophylline adenosine dipyridamole (CTAD) and citrate evaluation to survey unfractionated heparin treatment: a delayed centrifugation validation for anti-Xa measurement?]. / Évaluation du citrate théophylline adénosine dipyridamole (CTAD) et du citrate comme anticoagulant dans la surveillance du traitement par héparine non fractionnée : validation d'une centrifugation différée pour le dosage de l'anti-Xa.

Unfractionated heparin (UFH) is the main anticoagulante used in intensive care unit. The anticoagulant effect is monitored by activated partial thrombin time (aPTT) and anti-Xa activity (anti-Xa) measurement. However, delayed centrifugation induces platelet factor 4 (PF4) release and anti-Xa decrease. Several studies have concluded that aPTT and anti-Xa measurement should be performed within 2 hours in citrated anticoagulant but may be delayed longer in citrate theophylline adenosine and dypiridamol (CTAD) anticoagulant. The objective of this study was to compare the stability of both aPTT and anti-Xa in citrate and CTAD samples, and to determine the effect of delayed centrifugation on both aPTT, anti-Xa results, and PF4 release in citrate samples only. METHODS: aPTT and anti-Xa were measured in citrate and CTAD anticoagulant samples from 93 patients. Delayed centrifugation was performed in citrate samples from 31 additional patients, with hourly aPTT and anti-Xa measurement from 1 to 6 hours. In 14 of these last patients, PF4 release was also evaluated with Human CXCL4/PF4 Quantikine ELISA Kit. RESULTS: We observed a significant correlation between citrate and CTAD anticoagulant for aPTT (r2=0.94) and anti-Xa (r2=0.95). With Bland-Altman correlation, a minor bias was observed for anti-Xa (-0.025±0.041). Delayed centrifugation in citrated anticoagulant showed an excellent concordance from 1 to 4 hours for aPTT (-4.0±5.3 s) and anti-Xa (1.10-9±0.058 UI/mL) measurements. Moreover, PF4 release was not different between 1 hour (31.5±14.7 ng/mL) and 4 hours (33.8±11.8 ng/mL). CONCLUSION: We have demonstrated that anti-Xa measurement for unfractionated heparin should be done 4 hours in citrated plasma and that CTAD was not better than citrate. However, these initial findings require confirmation using other aPTT and calibrated anti-Xa assays.

Management of dabigatran after overdosage: two case reports and suggestions for monitoring.

: Bleeding is the main complication of anticoagulant treatments as dabigatran etexilate. In patients with atrial fibrillation, dabigatran, at certain doses, has been associated with similar rates of stroke and embolism, and a lower rate of major hemorrhage compared to warfarin. Before the recent possibility of reversing the anticoagulant effect of dabigatran with idarucizumab, prothrombin complex concentrate (PCC) was the main available treatment in cases of severe bleeding or emergency surgery . We describe two different cases with very high overdosage in which PCC or idarucizumab was used to reverse the effect of dabigatran etexilate.

Adjusted value of thromboprophylaxis in hospitalized obese patients: A comparative study of two regimens of enoxaparin: The ITOHENOX study.

Thromboprophylaxis is a mainstay of hospital care in patients at high risk of thrombosis. Fixed doses of low-molecular-weight heparin (LMWH) are recommended for thromboprophylaxis in patients admitted to hospital for an acute medical condition. However, the distribution of LMWH is weight-based, and the efficacy of standard doses in obese patients may be decreased. Data for obese patients are mainly available in bariatric surgery with extremely obese patients who are at greater risk of venous thromboembolism than those hospitalized for a medical condition. We conducted a randomized control trial in medically obese inpatients (BMI≥30kg/m2) assessing two regimens of enoxaparin (40mg and 60mg SQ daily) in order to determine whether a stronger dosage would achieve higher anti-Xa level suitable for thromboprophylaxis. Between September 2013 and April 2015, 91 patients were included in the study (mean (±standard deviation) age was 70.4±10.7years, average BMI 37.8±6.4kg/m2). Main indications of thromboprophylaxis were mainly acute infection (50%), acute respiratory failure (10%), acute congestive heart failure (9%) and acute rheumatic disorders (18%). Average anti-Xa activity, measured 4h after the third administration of enoxaparin was 0.25±0.09IU/mL in group 1 (enoxaparin 40mg) and 0.35±0.13IU/mL in group 2 (enoxaparin 60mg) (P<10-3). The proportions of patients with normal anti-Xa activity (between 0.32 and 0.54IU/mL) were 31% (n=11) and 69% (n=24) in group 1 and 2 respectively (P=0.007). The proportions of anti-Xa activity measurement below the normal range were 64% and 36% in group 1 and 2 (P<10-3) respectively. Subgroup analysis focusing on high weight patients (above 100kg, n=45) showed a marked difference in the proportion of patients with normal anti-Xa activity between group 1 (9%) and 2 (44%) (P=0.009). No venous thromboembolism occurred during the study and one patient in group 1 died because of hemorrhagic shock due to a gastric ulcer. Incidence of adverse events was not different between the two groups (P=0.52). In conclusion, the ITOHENOX study shows in medically obese inpatients that thromboprophylaxis with enoxaparin 60mg provides higher control of anti-Xa activity, without more bleeding complications than the standard enoxaparin regimen. This trial is registered with ClinicalTrials.gov, number NCT01707732.