Fibrin Network Formation and Lysis in Septic Shock Patients

Background: Septic shock patients are prone to altered fibrinolysis, which contributes to microthrombus formation, organ failure and mortality. However, characterisation of the individual patient’s fibrinolytic capacity remains a challenge due to a lack of global fibrinolysis biomarkers. We aimed to assess fibrinolysis in septic shock patients using a plasma-based fibrin clot formation and lysis (clot–lysis) assay and investigate the association between clot–lysis parameters and other haemostatic markers, organ dysfunction and mortality. Methods: This was a prospective cohort study including adult septic shock patients (n = 34). Clot–lysis was assessed using our plasma-based in-house assay. Platelet count, activated partial thromboplastin time (aPTT), international normalised ratio (INR), fibrinogen, fibrin D-dimer, antithrombin, thrombin generation, circulating fibrinolysis markers and organ dysfunction markers were analysed. Disseminated intravascular coagulation score, Sequential Organ Failure Assessment (SOFA) score and 30-day mortality were registered. Results: Three distinct clot–lysis profiles emerged in the patients: (1) severely decreased fibrin formation (flat clot–lysis curve), (2) normal fibrin formation and lysis and (3) pronounced lysis resistance. Patients with abnormal curves had lower platelet counts (p = 0.05), more prolonged aPTT (p = 0.04), higher lactate (p < 0.01) and a tendency towards higher SOFA scores (p = 0.09) than patients with normal clot–lysis curves. Fibrinogen and fibrin D-dimer were not associated with clot–lysis profile (p ≥ 0.37). Conclusion: Septic shock patients showed distinct and abnormal clot–lysis profiles that were associated with markers of coagulation and organ dysfunction. Our results provide important new insights into sepsis-related fibrinolysis disturbances and support the importance of assessing fibrinolytic capacity in septic shock.

Coagulation under Mild Hypothermia Assessed by Thromboelastometry

<b><i>Introduction:</i></b> While previous studies have shown a significant impact of extreme hypo- and hyperthermia on coagulation, effects of much more frequently occurring perioperative mild hypothermia are largely unknown. This study therefore aimed to analyze the effects of mild hypothermia using rotational thromboelastometry in vitro. <b><i>Materials and Methods:</i></b> Twelve healthy volunteers were included in this study. Standard thromboelastometric tests (EXTEM, INTEM, FIBTEM) were used to evaluate coagulation in vitro at 39, 37, 35.5, 35, and 33°C. Beyond standard thromboelastometric tests, we also evaluated the effects of mild hypothermia on the TPA-test (ClotPro, Enicor GmbH, Munich, Germany), a new test which aims to detect fibrinolytic capacity by adding tissue plasminogen activator to the sample. Data are presented as the median with 25/75th percentiles. <b><i>Results:</i></b> Extrinsically activated coagulation (measured by EXTEM) showed a significant increase in clot formation time (CFT; 37°C: 90 s [81/105] vs. 35°C: 109 s [99/126]; <i>p</i> = 0.0002), while maximum clot firmness (MCF) was not significantly reduced. Intrinsically activated coagulation (measured by INTEM) also showed a significant increase in CFT (37°C: 80 s [72/88] vs. 35°C: 94 s [86/109]; <i>p</i> = 0.0002) without significant effects on MCF. Mild hypothermia significantly increased both the lysis onset time (136 s [132/151; 37°C] vs. 162 s [141/228; 35°C], <i>p</i> = 0.0223) and lysis time (208 s [184/297; 37°C] vs. 249 s [215/358; 35°C]; <i>p</i> = 0.0259). <b><i>Conclusion:</i></b> This demonstrates that even under mild hypothermia coagulation is significantly altered in vitro. Perioperative temperature monitoring and management are greatly important and can help to prevent mild hypothermia and its adverse effects. Further investigation and in vivo testing of coagulation under mild hypothermia is needed.

Plasma fibrinolysis, inflammatory markers, and postthrombotic syndrome: preliminary findings from the Kids-DOTT Biobank

Plasma levels of markers of coagulation and inflammation have been identified as prognostic factors for adult postthrombotic syndrome (PTS). We aimed to determine whether plasma fibrinolytic capacity and cytokine levels during the first 3 months after provoked deep venous thrombosis (DVT) are associated with risk of PTS in young patients. We analyzed plasma biospecimens (6 weeks and 3 months after provoked DVT) and clinical data from a National Heart, Lung, and Blood Institute–sponsored multinational trial of anticoagulation for provoked venous thromboembolism in patients younger than age 21 years (Kids-DOTT). Patients with a provoked extremity DVT who had plasma samples available at both 6-week and 3-month post-DVT time points and PTS assessment at 1 year were included. We measured plasma fibrinolytic capacity using the Clot Formation and Lysis (CloFAL) assay and plasma cytokine levels by multiplex immunoassay. Logistic regression analyses evaluated prognostic associations with PTS. Seventy-nine patients were included (median age, 12.8 years; range, 0.04-20.8 years). PTS developed in 34%. Complete veno-occlusion at 6 weeks after diagnosis of DVT (odds ratio [OR], 3.12; 95% confidence interval [CI], 0.81-11.94; P = .097), low fibrinolytic capacity in plasma at 3 months post-DVT (OR, 2.71; 95% CI, 0.92-7.97; P = .07), and elevated serum amyloid A at 3 months post-DVT (OR, 2.85; 95% CI, 0.98-8.34; P = .055) were identified as putative prognostic factors for development of PTS. In multivariable logistic regression analysis, these factors did not retain a statistically significant independent association with PTS, but these preliminary results warrant further investigation in an independent data set to definitively evaluate these findings and identify additional potential prognostic factors for the development of PTS after a provoked DVT in young patients.

Circulating blood cells influence the fibrinolytic capacity of clots generated in the presence of detergent sclerosants

Objectives To investigate the effects of sodium tetradecyl sulphate and polidocanol on fibrinolytic potential of sclerosant-incubated clots. Methods Serial dilutions of sodium tetradecyl sulphate and polidocanol were incubated with platelet poor plasma and whole blood samples. Rotational thromboelastometry was used to determine the lysis of sclerosant-incubated clots in whole blood. Fibrin generation and fibrinolysis were quantified using an overall haemostatic potential assay on platelet poor plasma. Results Rotational thromboelastometry analysis of whole blood revealed increased maximum lysis in the presence of sodium tetradecyl sulphate but decreased maximum lysis at low concentrations of polidocanol. Clots generated using platelet poor plasma in the overall haemostatic potential assay demonstrated no significant change in fibrinolysis for both sclerosants at all concentrations measured. Discussion Sodium tetradecyl sulphate and polidocanol produce differing effects on the fibrinolytic potential depending on sample type and concentration. In whole blood, sodium tetradecyl sulphate produces clots more sensitive to lysis while polidocanol produced fibrinolytic-resistant clots.

Fibrinolysis during liver transplantation: analysis by the Thrombodynamics method

An issue in orthotopic liver transplantation (OLT) is the diagnosis of hyperfibrinolysis. The Thrombodynamics-4D assay (TD4D) is a videomicroscopy system allowing the dynamic analysis of fibrin clot. Fibrinolysis is highlighted by a change in clot intensity. The aim of this observational study was to evaluate the TD4D as a tool to diagnose fibrinolysis during OLT. Thirty consecutive patients were included. We studied a subset of 41 samples from 13 patients who demonstrated hyperfibrinolysis during OLT by global fibrinolytic capacity studied by the Lysis Timer (GFC/LT) and/or euglobulin clot lysis time (ECLT) and/or EXTEM maximum lysis (EXTEM ML) on ROTEM. Three samples exhibited fibrinolysis. They exhibited significantly shorter ECLT, higher lysis on EXTEM graphs, shorter GFC/LT clot lysis time and higher t-PA activity values. After adding urokinase, 13 samples exhibited fibrinolysis. In conclusion, TD4D allows the dynamic analysis of fibrin clot formation and lysis. It only recognises the most severe forms of hyperfibrinolysis during OLT.

Disturbed Laminar Blood Flow Causes Impaired Fibrinolysis and Endothelial Fibrin Deposition In Vivo

Endothelial expression of tissue-type plasminogen activator (t-PA) is crucial for maintaining an adequate endogenous fibrinolysis. It is unknown how endothelial t-PA expression and fibrinolysis are affected by blood flow in vivo. In this study, we investigated the impact of different blood flow profiles on endothelial t-PA expression and fibrinolysis in the arterial vasculature. Induction of disturbed laminar blood flow (D-flow) in the mouse carotid artery potently reduced endothelial t-PA messenger ribonucleic acid and protein expression, and caused fibrin deposition. En face immunohistochemistry demonstrated that arterial areas naturally exposed to D-flow had markedly lower endothelial t-PA levels than areas with sustained laminar blood flow (S-flow), and displayed pronounced fibrin deposition despite an intact endothelium. In t-PA and plasminogen-deficient mice, fibrin deposition did not extend into S-flow areas, indicating that areas of D-flow and S-flow differ, not only in fibrinolytic capacity, but also in coagulation. Furthermore, plasminogen accumulation was found at D-flow areas, and infusion of recombinant t-PA activated fibrinolysis and significantly reduced the fibrin deposits. In conclusion, D-flow potently impairs the fibrinolytic capacity and causes endothelial fibrin deposition in vivo. Our data also indicate that t-PA is the limiting factor for efficient fibrinolysis at the thrombosis-prone D-flow areas in the arterial vasculature.