An alternative pathway for fibrinolysis is activated in patients who have undergone cardiopulmonary bypass surgery and major abdominal surgery

Portal vein thrombosis in cirrhosis is not associated with intestinal barrier disruption or increased platelet aggregability

OBJECTIVE

Portal vein thrombosis (PVT) is a common complication of cirrhosis, but its pathogenesis is unclear. We tested the hypotheses that PVT is the result of platelet hyperactivity or intestinal barrier disruption.

METHODS

This study included 49 patients with cirrhosis (15 females) of mixed etiology. Based on spiral computed-tomography, the patients were divided into two groups: with PVT (n=16) and without PVT (n=33). Serum biomarkers of intestinal barrier integrity were endotoxins and zonulin, and platelet activity was assessed with multiple electrode aggregometry.

RESULTS

The levels of endotoxin (43.5±18.3ng/ml vs. 36.9±7.5ng/ml; P=0.19) and zonulin (56.3±31.1ng/ml vs. 69.3±63.1ng/ml; P=0.69) were not different between the patients with and without PVT. Moreover, endotoxin and zonulin did not correlate with the coagulation and platelet parameters. The platelet aggregability measured with the TRAP and the ADP tests was decreased in PVT patients. In the logistic regression analysis the PVT incidence was related to the levels of D-dimer and bilirubin as well as the TRAP test results. Patients with PVT presented with significantly higher levels of D-dimer (4.45±2.59 vs. 3.03±2.97mg/l; P<0.05) and prothrombin levels (175±98.8μg/ml vs. 115±72.9μg/ml; P<0.05) than patients without thrombosis. PVT could be excluded with a 90% negative predictive value when the D-dimer level was below 1.82mg/l.

CONCLUSIONS

Endotoxemia and platelet activity are not determinants of PVT in patients with cirrhosis. The D-dimer measurement has diagnostic significance for PVT in patients with liver cirrhosis.

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

Background

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

Methods

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

Results

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

Conclusions

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

Predictive blood coagulation markers for early diagnosis of venous thromboembolism after total knee joint replacement

Pulmonary embolism development may be prevented if asymptomatic venous thromboembolism (VTE) can be predicted and treated preoperatively or soon after total knee arthroplasty (TKA). The purpose of this study was to evaluate whether asymptomatic VTE can be predicted by blood coagulation markers preoperatively or early after TKA. This prospective single-centre study enrolled 68 patients (6 men, 62 women; mean age: 71 years) who underwent TKA between September 2004 and August 2009. Sixteen-row multidetector computed tomography was performed 4 days before and after surgery for diagnosis of asymptomatic VTE. Blood samples were taken to measure the plasma levels of soluble fibrin monomer complex (SFMC), D-dimer and cross-linked fibrin degradation products by leukocyte elastase (e-XDP) at 4 days preoperatively, and at 1 hour, 1 day and 4 days postoperatively. The preoperative SFMC, D-dimer and e-XDP levels did not differ significantly between the thrombus (n=36) and no-thrombus (n=32) groups. D-dimer and e-XDP levels showed the most significant increases at days 4 and 1, respectively, after surgery in the thrombus group. With cut-off points of 7.5 μg/ml for D-dimer and 8.2 U/ml for e-XDP, the sensitivities were 75% and 75%, and the specificities were 63% and 59%, respectively. By multiple logistic regression analysis, D-dimer at day 4 and e-XDP at day 1 postoperatively were independent markers for early diagnosis of VTE (odds ratio=1.61 and 1.19, P=0.01 and 0.04, respectively). The postoperative occurrence of new asymptomatic VTE may be predicted by D-dimer at day 4 and e-XDP at day 1 after TKA.

Contribution of neutrophil elastase to the lysis of obliterative thrombi in the context of their platelet and fibrin content

Leukocytes invade newly formed thrombi through interactions with platelets and fibrin and later contribute to the removal of fibrin deposits mainly through the action of neutrophil elastase. The present study attempts to express in quantitative terms the impact of neutrophils on the lytic processes in obliterative thrombi based on the local presence of elastase-specific fibrin degradation products (NE-FDP) in relation to the leukocyte, platelet and fibrin content of thrombi. Immunofluorescent detection of fibrin, NE-FDP and platelet antigens was performed in sections of thrombi from 28 patients subjected to thrombectomy in combination with DNA-staining for identification of nucleated cells. The digitalized fluorescent microscopic images were decomposed according to the color channel of each thrombus constituent. The integrated intensity values for all thrombus constituents were statistically evaluated with correlation, hierarchical agglomerative clustering , Hotelling's T² and F-statistics. Association between NE-FDP and leukocyte content of thrombi is evidenced by a significant Pearson correlation coefficient of 0.71 (p = 0.00002). Cluster analysis reveals two classes of thrombi according to NE-FDP, leukocyte and platelet content and also two according to NE-FDP, leukocyte and fibrin content. When NE-FDP, fibrin and platelet content is normalized to the leukocyte count in the same thrombus, clusters with platelet-related thrombolytic resistance (inversely related NE-FDP and platelet content) and advanced cell-dependent thrombolysis (inversely related NE-FDP and fibrin content) are identified. These distinct patterns of thrombus constituents are snapshots of characteristic stages in the cell-dependent thrombolysis, which indicate a clot-stabilizing role for platelets in this process similar to their impact on the plasmin-dependent lysis.

The effect of hepatectomy on coagulation: an evaluation by thromboelastography

OBJECTIVES

Liver has a major role in coagulation. The hemostatic derangements measured by the mostly used coagulation parameters as prothrombin time, activated partial thromboplastin time, and thrombocyte count do not always correlate with the bleeding associated with liver diseases and these factors do not measure the thrombotic risks. So, thromboelastography is used in new clinical and laboratory research. The aim of this study is to study the effect of different levels of hepatectomy on coagulation.

METHODS

Laparatomy, 40% hepatectomy, and 70% hepatectomy was performed in three different groups of rats. Prothrombin time, international normalized ratio, activated partial thromboplastin time, thrombocyte count, fibrinogen levels, and thromboelastography parameters were obtained at the 0, 6, and 24th hour of the study.

RESULTS

Fibrinogen level at the 24th hour was greater than the early hours in both of the hepatectomy groups. Prothrombin time and international normalized ratio values were significantly higher in hepatectomy groups than in the sham group. There were no statistically significant difference in the clotting time, clot formation time, alpha-angle, and maximum clot firmness values in any of the thromboelastography channels, in any of the study times, in between the sham, 40% hepatectomy, and 70% hepatectomy groups.

CONCLUSION

There is no difference between 40 and 70% hepatectomy when the coagulopathy is evaluated. The coagulation derangements as reflected by the increase in fibrinogen and prolongation of prothrombin time and activated partial thromboplastin time after hepatectomy were not supported by thromboelastography parameters in this study.

Coagulation and fibrinolytic protein kinetics in cardiopulmonary bypass

The development of Cardiopulmonary Bypass (CPB) catopulted the field of cardiothoracic surgery into a new dimension--one that changed the lives of individuals with congenital and acquired heart disease worldwide. Despite its contributions, CPB has clear limitations and creates unique challenges for clinicians and patients alike, stemming from profound hemostatic pertubations and accompanying risk for bleeding and possibly thrombotic complications.