Hemostatic Profile Research Articles

Cyanotic congenital heart disease (CCHD): focus on hypoxemia, secondary erythrocytosis, and coagulation alterations.

Children with cyanotic congenital heart disease (CCHD) have complex alterations in their whole blood composition and coagulation profile due to long-standing hypoxemia. Secondary erythrocytosis is an associated physiological response intended to increase circulating red blood cells and oxygen carrying capacity. However, this response is frequently offset by an increase in whole blood viscosity that paradoxically reduces blood flow and tissue perfusion. In addition, the accompanying reduction in plasma volume leads to significant deficiencies in multiple coagulation proteins including platelets, fibrinogen and other clotting factors. On the one hand, these patients may suffer from severe hyperviscosity and subclinical 'sludging' in the peripheral vasculature with an increased risk of thrombosis. On the other hand, they are at an increased risk for postoperative hemorrhage due to a complex derangement in their hemostatic profile. Anesthesiologists caring for children with CCHD and secondary erythrocytosis need to understand the pathophysiology of these alterations and be aware of available strategies that lessen the risk of bleeding and/or thrombosis. The aim of this review is to provide an updated analysis of the systemic effects of long-standing hypoxemia in children with primary congenital heart disease with a specific focus on secondary erythrocytosis and hemostasis.

Platelet hyperactivity and fibrin clot structure in transient ischemic attack individuals in the presence of metabolic syndrome: a microscopy and thromboelastography study.

BackgroundStrokes are commonly preceded by transient ischemic attacks (TIAs). TIA is often associated with metabolic syndrome (causing chronic inflammation), resulting in a proinflammatory- and procoagulant-environment. The aim of this study was to determine whether platelet- and fibrin network-morphology or coagulation profiles of individuals that suffered a TIA in the presence of metabolic syndrome was altered when compared to healthy individuals.Materials and methodsThe study consisted of 40 voluntary participants. Twenty individuals that suffered a TIA in the previous 48 h with at least two metabolic syndrome risk factors present and twenty healthy age-matched controls. Scanning electron- and atomic force microscopy was used to study platelet- and fibrin-morphology, atomic force microscopy was used to study platelet- and fibrin fiber-elasticity and thromboelastography® for the study of coagulation profiles. Statistical analysis was performed to compare the two groups. In all cases a p-value of less than 0.05 was considered statistically significant.ResultsPlatelets of the control group appeared spherical with few pseudopodia present while the platelets of the TIA individuals presented with numerous pseudopodia and spreading, indicating activation. Platelet aggregation was also present. The fibrin networks of the healthy individuals consist of thick and thin fibers that form an organized network of fibers. The fibrin networks of the TIA individuals appeared less organized with less taut fibers. Fibrin fiber thickness was found to be significantly increased in the TIA group (p-value <0.001) when compared to healthy controls. The thicker fibers formed irregular networks with thick masses of fibrin fibers. Platelet and fibrin fiber elasticity was found to be significantly lower in the experimental group (p-value 0.0042 and p-value 0.0007 respectively). The hemostatic profiles of the diseased individuals did not differ significantly (p-value > 0.05) from the healthy controls, indicating a normal functioning coagulation cascade.ConclusionThe findings indicate that pathological clot formation is not caused by alterations in the coagulation cascade but rather by the premature activation of platelets (as a result of chronic inflammation) that in turn causes altered fibrin formation.

Elevated thrombin activatable fibrinolysis inhibitor levels in women with polycystic ovary syndrome

Objective: The aim of the present study was to evaluate plasma concentrations of thrombin activatable fibrinolysis inhibitor (TAFI) in relation with hormonal, metabolic, and hemostatic profile in patients with and without polycystic ovary syndrome (PCOS).Study design: A total of 38 women with PCOS and 37 age and body mass index (BMI) matched controls were eligible for the study. Hirsutism scores, hormonal, metabolic, and hemostatic profile as well as TAFI levels were evaluated in each subject.Results: Women with PCOS exhibited higher plasma concentrations of TAFI levels than controls (107.42 ± 34.77% versus 91.86 ± 23.88%, p = 0.027). TAFI levels were significantly correlated positively with BMI, fasting insulin levels, modified Ferriman Gallwey scores and Homeostasis Model Assessment (HOMA) index, systolic blood pressure, and waist and hip circumferences, whereas negatively correlated with activated partial thromboplastin time (p < 0.05). However, after adjustment for all possible confounding factors, none of the parameters was significantly deterministic on TAFI levels.Conclusion: The data of the present study suggested that plasma TAFI levels were higher in women with PCOS as compared with healthy age and BMI-matched controls, indicating impaired fibrinolysis. This hypofibrinolytic state may be responsible for the increased cardiovascular disease risk in women with PCOS.

Rebalanced Hemostasis in Patients with Acute Liver Failure.

Patients with acute liver failure (ALF) have substantial alterations in their hemostatic system. Since an international normalized ratio of ≥ 1.5 is part of the definition of the syndrome, it has long been believed that patients with ALF had a hemostasis-related bleeding tendency. Recent data, however, show that spontaneous bleeding in ALF is rare. In addition, thrombotic complications may be more common than spontaneous bleeding complications. Laboratory studies have suggested that patients with ALF may be in hemostatic balance as a result of a commensurate decline in pro- and anti-hemostatic factors. The unstable nature of the hemostatic balance in ALF may explain the occurrence of both bleeding and thrombotic complications. The hemostatic profile of patients with ALF includes hypercoagulable features, including von Willebrand factor/a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 unbalance, elevated levels of highly procoagulant, platelet-derived microparticles, and a profound hypofibrinolytic status. These hypercoagulable features may contribute to systemic thrombotic complications, but may also drive intrahepatic clot formation. Studies in experimental animal models of ALF have demonstrated that intrahepatic clot formation contributes to disease progression. The clinical consequences of these new insights in the hemostatic system of patients with ALF will be discussed in this review.

Ethnic-specific relationships between haemostatic and oxidative stress markers in black and white South Africans: The SABPA study

Haemostatic- and oxidative stress markers are associated with increased cardiovascular risk. In the black population, evidence exists that both an imbalance in the haemostatic system and oxidative stress link with the development of hypertension. However, it is unclear whether these two risk components function independently or are related, specifically in the black population, who is known to have a high prevalence of stroke. We aimed to investigate associations between the haemostatic system and oxidative stress in black and white South Africans. We performed a cross-sectional study including 181 black (mean age, 44; 51.4% women) and 209 white (mean age, 45; 51.7% women) teachers. Several markers of the haemostatic- (von Willebrand factor, fibrinogen, plasminogen activator inhibitor-1, d-dimer and clot lysis time) and oxidant–antioxidant (serum peroxides, total glutathione, glutathione peroxidase- and glutathione reductase activities) systems were measured. Along with a worsened cardiovascular profile, the black group had higher haemostatic-, inflammation- and oxidative stress markers as well as decreased glutathione peroxidase activity. In multiple regression analyses, fibrinogen was positively associated with serum peroxides (p < 0.001) in both ethnic groups. In the black population, we found negative associations of von Willebrand factor and clot lysis time with glutathione peroxidase activity (p ≤ 0.008), while a positive association existed between clot lysis time and serum peroxides (p = 0.011) in the white population. We conclude that in the black population, decreased GPx activity accompanies an altered haemostatic profile, while in the white population associations may suggest that serum peroxides impair fibrin clot lysis.

Limitations of component therapy for massive haemorrhage: is whole blood the whole solution?

Limitations of component therapy for massive haemorrhage: is whole blood the whole solution?

Haemostatic profile of reconstituted blood in a proposed 1:1:1 ratio of packed red blood cells, platelet concentrate and four different plasma preparations.

The concept of haemostatic resuscitation implies early and high-volume plasma transfusion. We investigated the haemostatic profile of reconstituted whole blood prepared in a 1:1:1 ratio of blood, platelets and plasma. This consisted of packed red blood cells, platelet concentrate and four different plasma variants: fresh frozen; solvent-detergent; lyophilised quarantine; and lyophilised methylene blue-inactivated plasma. Haematocrit, platelet count, endogenous thrombin potential and coagulation factor activity were significantly lower in reconstituted blood compared with citrated whole blood (p < 0.01). Except for lyophilised methylene blue-inactivated plasma, no substantial differences between plasma variants in coagulation factor activity, endogenous thrombin potential and standard coagulation tests were observed. After reconstitution, haematocrit and platelet counts were slightly above recommended transfusion triggers, most thromboelastometry (ROTEM(®)) parameters were within the normal range and fibrinogen concentrations were between 1.57 g.l(-1) and 1.91 g.l(-1). Reconstitution of whole blood in a 1:1:1 ratio resulted in significant dilution of haematocrit and platelet count, but values remained above limits recommended by transfusion guidelines. Fibrinogen concentrations of reconstituted whole blood were also significantly reduced, and these were below the threshold value for supplementation recommended by recent guidelines.

Prospective observational study of hemostatic alterations during adult extracorporeal membrane oxygenation (ECMO) using point-of-care thromboelastometry and platelet aggregometry.

To characterize the longitudinal hemostatic profile during adult ECMO using point-of-care tests (POCT) for coagulation and to compare these parameters to standard laboratory tests. In addition, the clinicians' responses during bleeding episodes using available information were compared to a POCT-based response. Prospective observational cohort study. ECMO-referral center in a university teaching hospital. Ten critically ill adult ECMO patients. Daily laboratory coagulation profile, transfusion history and near-daily thromboelastometry (ROTEM®) and platelet aggregometry (Multiplate®). Six male and four female patients, seven with VA- and three with VV-ECMO were studied over 110 days. Seventy-five thromboelastometry (TEM) and 36 platelet aggregometry (MEA) results were analyzed. A majority of TEM values were within the normal range, except for FIBTEM (majority high), which remained consistent over long (>5 days) ECMO runs. In MEA there were low values, particularly in the adenosine diphosphate- and ristocetin-induced assay, implying possibly a vWF-factor or GpIb-receptor defect. There was correlation between laboratory and POCT as well as good correlation between the clot firmness after 10 minutes (A10) and the maximum clot firmness in ROTEM, suggesting that reliable information can be obtained within 15 minutes. Twenty-two bleeding episodes were observed in five patients. When comparing the clinicians' response to a transfusion algorithm based on POCT, there was a concordance in less than 20% of episodes. POCT for coagulation can provide specific, reliable, and timely information during bleeding episodes and the use of targeted therapy algorithms could improve outcomes and reduce costs.

Hemostatic Profile and Associated Factors of Hemostatic Abnormality in Human Immunodeficiency Virus Infected Adults Attending Jimma University Specialized Hospital, Southwest Ethiopia: A Case-Control Study

Background: Human immunodeficiency virus infection has been proposed to inflict an insult on hemostatic system which involves endothelium, platelet and coagulation proteins. Information regarding hemostatic profile in human immunodeficiency virus infected patients is limited and contradicting too. Method: A case control study was conducted from April to May 2014 in Jimma University specialized hospital, involving 96 HIV infected patients and 96 healthy controls that came consecutively to comprehensive chronic care center and voluntary counseling and testing (VCT) center respectively. Socio demographic and clinical data were obtained using structured questionnaire. For the purpose of hemostasis tests, 2.7ml of venous blood sample was collected in a 3ml citrated (3.2%) vacuum tube. Platelet count and CD4 count was determined from a 3ml EDTA sample. Mixing study was undertaken for prolonged coagulation tests. Data were analyzed using SPSS, version 20. Result: The mean value of prothrombin time (PT), international normalized ratio(INR), activated partial thromboplastin time(APTT) and fibrinogen level was significantly higher in case group than control (p< 0.001, 0.01, <0.001 and <0.001) while mean platelet count was significantly lower in case group (p<0.0001). Mixing study showed correction of 35(87.5%) of 40 prolonged PT both in immediate and delayed test while 58(95.1%) of 60 prolonged activated APTT fail to correct in both situations. A CD4 count of less than 200cells/mm 3(AOR=8.8, 95% CI (1.8-42.4)) and HAART (AOR=3.4, 95%CI (1.2-10.1)) use were significantly associated with prolonged PT while a CD4 count of less than 200cells/mm3 (AOR=11.55, 95% CI (1.25-106)) was significantly associated with prolonged APTT. Conclusion: There was a significant mean difference between case and control groups with respect to PT, APTT, platelet count and fibrinogen level. Direction of the finding points towards presence of inhibitors and factor deficiency which demands in depth investigation and corresponding intervention.

Changes in blood coagulation after colloid administration in patients undergoing total hip arthroplasty: comparison between pentastarch and tetrastarches, a randomized trial.

BackgroundHydroxyethyl starch (HES) solutions are used as plasma expanders for correcting hypovolemia, but can lead to impaired coagulation. We evaluated the changes in hematological and hemostatic profiles with three types of HES.MethodsPatients were randomized to receive volume replacement with 10% pentastarch 260/0.45 in 0.9% saline (Group-PEN, n = 25), 6% tetrastarch 130/0.4 in 0.9% saline (Group-TETS, n = 25), or 6% tetrastarch 130/0.4 in a balanced electrolyte solution (Group-TETB, n = 25). Coagulation was assessed using rotational thromboelastometry (ROTEM®) and other laboratory tests were performed, including measurements of hematological and hemostatic parameters and electrolytes.ResultsPost-operative ROTEM® parameters changed toward hypocoagulable states in all groups. The post-operative parameters of EXTEM and FIBTEM were more impaired in Group-PEN than in Group-TETB. The percentage change in INTEM clot formation time (P = 0.004) and α-angle (P = 0.003) were smaller in Group-TETS and Group-TETB than in Group-PEN. The percentage change in the FIBTEM maximum clot firmness was greatest in Group-PEN (P = 0.011). The international normalized ratio of prothrombin time (P < 0.001) and the activated partial thromboplastin time (P < 0.001) were significantly prolonged in Group-PEN compared to those of Group-TETB.ConclusionsThe 6% HES 130/0.4 in a balanced electrolyte solution seemed to have less of an impact on blood coagulation than the 10% HES 260/0.45. No differences in hemostatic profile were observed between the balanced electrolyte and saline-based 6% HES 130/0.4.

Assessment of thrombin generation using thromboelastometry in cirrhotic patients with hepatocellular carcinoma undergoing liver transplantation

Due to the mixed etiology of liver disease, cirrhotic patients with hepatocellular carcinoma may have either a pro-thrombotic or a bleeding tendency. Haemostatic assessment and blood management represent key issues during liver transplantation (LT) having a significant impact on survival and postoperative outcome. Our aim was to assess haemostatic profile in liver transplant recipients with hepatocellular carcinoma (HCC) and to evaluate its impact on perioperative anaesthetic management. We prospectively included 122 patients that underwent liver transplantation between January and December 2013. Exclusion criteria were incomplete data recall, preoperative anticoagulation treatment, acute liver failure and emergency re-transplantation. Coagulation was assessed using standard coagulation tests and rotational thromboelastometry (ROTEM®) assay performed preoperative and 15 minutes after reperfusion of the liver. We recorded introperative blood loss, transfusion requirements, Post Anaesthesia Care Unit length of stay and incidence of postoperative renal, pulmonary, thrombotic and hemorrhagic complications. After we applied the exclusion criteria, 80 patients were included in the final analysis: 24 patients in the HCC groupand 56 in the non-HCC group. Patients with HCC had increased preoperative thrombin generation demonstrated by a shorter clot formation time (142 vs. 381 sec, p= 0.01, 95% CI[41.9, 292.4] ) and a shorter time to maximum velocity of clot formation (153 vs. 209, p=0.027, 95% CI [6.59, 105.3] ). Intraoperative findings showed no differences in blood loss between the two groups, but lower fresh frozen plasma requirements (11.5 vs. 16.6 units, p =0.031) was observed in the HCC group. Intraoperative ROTEM® variables were similar in both groups measured after reperfusion of the graft. No statistically significant differences in postoperative outcome were observed between groups. In conclusion, patients in HCC group have increased preoperative thrombin generation as demonstrated by ROTEM derived parameters. During major abdominal surgery, like LT, and increased blood loss thrombin generation is similar in patients with and without HCC, demonstrating that haemostatic reserve is limited in HCC group.

Age-Related Developmental Clotting Profile and Platelet Aggregation in Foals Over the First Month of Life

This study aimed to evaluate how selected clotting parameters and platelets' responsiveness change in healthy full-term foals during the first 4 weeks after foaling. Blood samples were collected from each animal every 3 days from day 1 until day 30 after foaling and were tested for prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fb) concentration, platelet (Plt) count, percentage of aggregation and slope. One-way repeated measures analysis of variance, followed by Bonferroni post hoc comparison test, was applied to determine statistical effect of day of life on studied hemostatic parameters. Significant effect of time was found for PT (P < .0005), APTT (P < .0001), and Fb concentration (P < .05). No statistical significant effect of days of life was found for Plt (P = .19), whereas platelets aggregation changed (P < .0001) during the experimental period. The results obtained in the present study improves the knowledge about blood coagulation and platelet responsiveness in foals during the first month of life showing how hemostatic parameters change at this stage and provide specific information on routine coagulation tests that may support monitoring foal's hemostatic profile during neonatal period.

The whole is greater than the sum of its parts: hemostatic profiles of whole blood variants.

Mounting evidence highlighting the benefits of hemostatic resuscitation has led to a renewed interest in whole blood (WB) and reconstituted WB (RWB). However, few data exist to characterize the clotting profiles of these variants. This study characterizes banked WB variants and RWB in standard 1:1:1 and 2:1:1 transfusion ratios of packed red blood cells, fresh frozen plasma, and platelets (PLTs). We hypothesized that the global hemostatic profile of 1:1:1 RWB is superior to 2:1:1 RWB and that PLT-modified WB (MWB) is superior to 1:1:1 RWB. Twenty-three units of packed red blood cells, fresh frozen plasma, and PLTs were obtained from the regional blood collection center and mixed to create 23 1:1:1 and 23 2:1:1 RWB units. Freshly donated WB units were obtained and used to create 11 of each nonmodified WB (NMWB) (room temperature and cooled) and MWB (room temperature and cooled) variants. International normalized ratio (INR)/partial thromboplastin time (PTT), complete blood cell count, functional studies, and an extensive panel of procoagulant and anticoagulant factor assays were performed on all products. The 1:1:1 RWB had significantly lower INR and PTT (1.31 vs. 1.55, p = 0.0029; 42 seconds vs. 50 seconds, p = 0.0008) and higher activity of factors II, V, VII, VIII, IX, and X; antithrombin III, as well as protein C and higher fibrinogen levels than did 2:1:1 RWB (factor IX, 86% vs. 70%, p = 0.0313; fibrinogen, 242 mg/dL vs. 202 mg/dL, p = 0.0385). There were no differences in INR/PTT or factor activity between MWB and NMWB. However, MWB had greater maximum clot firmness (MCF) by rotational thromboelastometry tissue factor-activated extrinsic clotting cascade measures than did NMWB (MCF, 61 mm vs. 50 mm, p = 0.0031). MWB also had greater MCF by rotational thromboelastometry tissue factor-activated extrinsic clotting cascade measures than did 1:1:1 RWB (MCF, 61 mm vs. 45 mm, p = 0.0005). Although 1:1:1 RWB had a superior clotting profile relative to 2:1:1 RWB, MWB exhibited even better global hemostasis than did 1:1:1 RWB. Characterization of factor-level and functional clotting differences between WB variants is imperative for understanding the clinical benefits of hemostatic resuscitation.

Electrokinetic and hemostatic profiles of nonwoven cellulosic/synthetic fiber blends with unbleached cotton.

Greige cotton contains waxes and pectin on the outer surface of the fiber that are removed when bleached, but these components present potential wound dressing functionality. Cotton nonwovens blended with hydrophobic and hydrophilic fibers including viscose, polyester, and polypropylene were assessed for clotting activity with thromboelastography (TEG) and thrombin production. Clotting was evaluated based on TEG measurements: R (time to initiation of clot formation), K (time from end of R to a 20 mm clot), α (rate of clot formation according to the angle tangent to the curve as K is reached), and MA (clot strength). TEG values correlate to material surface polarity as measured with electrokinetic parameters (ζplateau, Δζ and swell ratio). The material surface polarity (ζplateau) varied from −22 to −61 mV. K values and thrombin concentrations were found to be inversely proportional to ζplateau with an increase in material hydrophobicity. An increase in the swell ratios of the materials correlated with decreased K values suggesting that clotting rates following fibrin formation increase with increasing material surface area due to swelling. Clot strength (MA) also increased with material hydrophobicity. Structure/function implications from the observed clotting physiology induced by the materials are discussed.

Plasmin-loaded echogenic liposomes for ultrasound-mediated thrombolysis.

Plasmin, a direct fibrinolytic, shows a significantly superior hemostatic safety profile compared to recombinant tissue plasminogen activator (rtPA), the only FDA-approved thrombolytic for the treatment of acute ischemic stroke. The improved safety of plasmin is attributed to the rapid inhibition of free plasmin by endogenous plasmin inhibitors present in very high concentrations (1μM). However, this rapid inhibition prevents the intravenous (IV) administration of plasmin. In emergency situations, catheter-based local administration is not practical. There is a need for an alternative technique for IV administration of plasmin. A possible solution is the encapsulation of plasmin in echogenic liposomes (ELIP) for protection from inhibitors until ultrasound (US)-triggered release at the clot site. ELIP are bilayer phospholipid vesicles with encapsulated gas microbubbles. US induces oscillation and collapse of the gas bubbles, which facilitates ELIP rupture and delivery of the encapsulated contents. Plasmin-loaded ELIP (PELIP) were manufactured and characterized for size, gas and drug encapsulations, and in vitro thrombolytic efficacy using a human whole blood clot model. Clots were exposed to PELIP with and without exposure to US (center frequency 120kHz, pulse repetition frequency 1667Hz, peak-to-peak pressure of 0.35MPa, 50% duty cycle). Thrombolytic efficacy was calculated by measuring the change in clot width over a 30-min treatment period using an edge detection MATLAB program. The mean clot lysis obtained with PELIP in the presence of US exposure was 31% higher than that obtained without US exposure and 15% higher than that obtained with rtPA treatment (p < 0.05).The enhanced clot lysis is attributed to the US-mediated release of plasmin from the liposomes.

Short- and Long-term exercise induced alterations in haemostasis: a review of the literature

Although regular exercise is beneficial for health, exercise-related thrombotic events, such as venous thromboembolism and myocardial infarctions, are occasionally observed. These events are characterized by a prothrombotic condition in which interactions between coagulation factors, the vessel wall and the fibrinolytic system play an important role. Apparently, various durations and intensities of exercise have different effects on haemostasis and especially high intensity exercise tends to increase the risk of thrombotic events. However, the mechanisms behind this have not been entirely established. In this review we provide an overview of the various effects of the different intensities and durations of exercise on haemostasis. Overall, the haemostatic profile is mainly affected by the intensity of exercise; and is more pronounced after high (>80%) compared to low intensity (<60%), as reflected by increased platelet and coagulant activity. These findings are in line with the increased risk of exercise-induced thrombotic events during high intensity exercise.

Relationship between ADAMTS13 activity, von Willebrand factor antigen levels and platelet function in the early and late phases after TIA or ischaemic stroke

BackgroundReduced ADAMTS13 activity is seen in thrombotic thrombocytopenic purpura (TTP), and may lead to accumulation of prothrombotic ultra-large von Willebrand factor (ULVWF) multimers in vivo. ADAMTS13 activity and its relationship with VWF antigen (VWF:Ag) levels and platelet function in ‘non-TTP related’ TIA or ischaemic stroke has not been comprehensively studied. MethodsIn this prospective pilot observational analytical case–control study, ADAMTS13 activity and VWF:Ag levels were quantified in platelet poor plasma in 53 patients in the early phase (≤4weeks) and 34 of these patients in the late phase (≥3months) after TIA or ischaemic stroke on aspirin. Data were compared with those from 22 controls not on aspirin. The impact of ADAMTS13 on platelet function in whole blood was quantified by measuring Collagen-ADP (C-ADP) and Collagen-Epinephrine closure times on a platelet function analyser (PFA-100®). ResultsMedian ADAMTS13 activity was significantly reduced in the early phase (71.96% vs. 95.5%, P <0.01) but not in the late phase after TIA or stroke compared with controls (86.3% vs. 95.5%, P=0.19). There was a significant inverse relationship between ADAMTS13 activity and VWF:Ag levels in the early phase (r=−0.31; P=0.024), but not in the late phase after TIA or stroke (P=0.74). There was a positive correlation between ADAMTS13 activity and C-ADP closure times in early phase patients only, likely mediated via VWF:Ag levels. DiscussionADAMTS13 activity is reduced and VWF:Ag expression is increased within 4weeks of TIA or ischaemic stroke onset, and can promote enhanced platelet adhesion and aggregation in response to stimulation with collagen and ADP via VWF-mediated pathways. These data improve our understanding of the dynamic haemostatic and thrombotic profiles of ischaemic cerebrovascular disease (CVD) patients, and are important in view of the potential future role that ADAMTS13 may have to play as an anti-thrombotic agent in CVD.

Progression of plasma D-dimer concentration and coagulopathies during hospitalization in horses with colic.

To assess the progression of plasma D-dimer concentrations and coagulation status in horses with different types of colic. Prospective clinical observational study performed between March 2004 and September 2008. Veterinary university teaching hospital. Horses admitted and treated for colic and hospitalized for >48 hours were considered. Animals were classified by diagnosis into medical obstructive conditions (MO), surgical obstructive conditions (SO), inflammatory conditions, and ischemic lesions (IS). Three blood samples were obtained from each horse (admission, at 24-48 h [or after surgery] and upon discharge). For each sample, plasma D-dimer concentration, prothrombin time, activated partial thromboplastin time, antithrombin activity, and the presence of subclinical disseminated intravascular coagulation were determined. When median plasma D-dimer concentration values at admission and after 24-48 hours were compared, they were different but stable in horses with MO (1.29-1.95 nmol/L) and inflammatory conditions (5.70-6.69 nmol/L). However, 10-fold and 5-fold increases were observed, respectively, in SO (2.08 to 16.38 nmol/L) and IS (3.08 to 15.91 nmol/L) in the postoperative period. By 24-48 hours, the percentage of horses with coagulopathy increased in most groups (MO, 43 to 58%; SO, 50 to 96%, IS, 53 to 90%). By the time of discharge, 87% of horses with SO problems and 89% of horses with IS still had some form of coagulopathy documented. Throughout hospitalization, horses with MO problems had less severe coagulopathy and lower plasmatic D-dimer concentrations compared to other groups of horses. On admission, most horses with inflammatory conditions presented with coagulopathy. At 24-48 hours of hospitalization and following surgery, the hemostatic profile can differ markedly when compared to admission values.

Never-frozen liquid plasma blocks endothelial permeability as effectively as thawed fresh frozen plasma.

Thawed fresh frozen plasma (TP) is a preferred plasma product for resuscitation but can only be used for up to 5 days after thawing. Never-frozen, liquid plasma (LQP) is approved for up to 26 days when stored at 1°C to 6°C. We have previously shown that TP repairs tumor necrosis factor α (TNF-α)-induced permeability in human endothelial cells (ECs). We hypothesized that stored LQP repairs permeability as effectively as TP. Three single-donor LQP units were pooled. Aliquots were frozen, and samples were thawed on Day 0 (TP0) then refrigerated for 5 days (TP5). The remaining LQP was kept refrigerated for 28 days, and aliquots were analyzed every 7 days. The EC monolayer was stimulated with TNF-α (10 ng/mL), inducing permeability, followed by a treatment with TP0, TP5, or LQP aged 0, 7, 14, 21, and 28 days. Permeability was measured by leakage of fluorescein isothiocyanate-dextran through the EC monolayer. Hemostatic profiles of samples were evaluated by thrombogram and thromboelastogram. Statistical analysis was performed using two-way analysis of variance, with p < 0.05 deemed significant. TNF-α increased permeability of the EC monolayer twofold compared with medium control. There was a significant decrease in permeability at 0, 7, 14, 21, and 28 days when LQP was used to treat TNF-α-induced EC monolayers (p < 0.001). LQP was as effective as TP0 and TP5 at reducing permeability. Stored LQP retained the capacity to generate thrombin and form a clot. LQP corrected TNF-α-induced EC permeability and preserved hemostatic potential after 28 days of storage, similar to TP stored for 5 days. The significant logistical benefit (fivefold) of prolonged LQP storage improves the immediate availability of plasma as a primary resuscitative fluid for bleeding patients.

Differential associations of oral estradiol and conjugated equine estrogen with hemostatic biomarkers

The risk of venous thrombosis (VT) associated with oral hormone therapy (HT) may differ by type of estrogen compound. To compare the thrombotic profile of women using oral conjugated equine estrogens (CEE) with that of women using oral estradiol (E2). In postmenopausal, female, health maintenance organization (HMO) members with no history of VT, we measured thrombin generation, levels of factor VII activity, antithrombin activity and total protein S antigen. Mean levels of hemostasis biomarkers were cross-sectionally compared by use and type of estrogen using multiple linear regressions. The type of estrogen used was determined primarily by the HMO formulary, which changed its preferred estrogen from CEE to E2 during the study period. The sample included 92 E2 users and 48 CEE users, with a mean age of 64.1 years and mean BMI of 29.1 kg m(-2) . Twenty-seven per cent of HT contained medroxyprogesterone acetate. Compared with E2 users, CEE users had greater thrombin generation peak values and endogenous thrombin potential, and lower total protein S (multivariate adjusted differences of 49.8 nm (95% CI, 21.0, 78.6), 175.0 nm × Min (95% CI, 54.4, 295.7) and -13.4% (95% CI, -19.8, -6.9), respectively). Factor VII and antithrombin levels were not different between E2 and CEE users. Results were similar in subgroups of users of unopposed HT, opposed HT, low-dose estrogen and standard dose estrogen. The hemostatic profile of women using CEE is more prothrombotic than that of women using E2. These findings provide further evidence for a different thrombotic risk for oral CEE and oral E2.