Efficacy of Coagulofibrinolytic Markers for Postoperative Prediction of Venous Thromboembolism in Colorectal Surgery Patients: A Retrospective Observational Study

Objectives

A low rate of the incidence of venous thromboembolism (VTE) after surgeries that are preoperatively classified as having high risk of VTE has been reported in recent years. We seek to identify the optimal cases to receive perioperative pharmacologic thromboprophylaxis. In this study, we evaluated the incidence rate of VTE among patients undergoing colorectal surgery who did not receive perioperative pharmacologic thromboprophylaxis, and the ability of coagulofibrinolytic markers to predict the postoperative development of VTE.

Methods

We retrospectively analyzed the rate of postoperative development of VTE in 70 patients undergoing elective colorectal surgery without perioperative pharmacologic thromboprophylaxis and the ability of coagulofibrinolytic markers to predict the development of VTE.

Results

The incidence of VTE was observed in 11 patients (15.7%); all cases were asymptomatic and distal-type deep vein thrombosis (DVT). Comparisons of time course changes in perioperative coagulofibrinolytic markers between patients with and without DVT revealed significant differences in soluble fibrin (SF), thrombin-antithrombin complex (TAT), fibrin/fibrinogen degradation product (FDP) and D-dimer. Dynamic postoperative physiological coagulofibrinolytic responses were shown, but all four markers at each postoperative point demonstrated moderate accuracy (median area under the curve [AUC]: 0.788, median sensitivity: 0.865, median specificity: 0.644) for predicting the development of DVT.

Conclusions

The incidence of postoperative VTE was low in patients with colorectal surgery even in those who did not receive perioperative pharmacologic thromboprophylaxis. SF, TAT, FDP and D-dimer were useful for predicting the development of DVT when we set cut-off values taking the physiological perioperative coagulofibrinolytic responses into consideration.

Pathomechanisms Underlying Hypoxemia in Two COVID-19-Associated Acute Respiratory Distress Syndrome Phenotypes: Insights From Thrombosis and Hemostasis

BACKGROUND

The pathomechanisms of hypoxemia and treatment strategies for type H and type L acute respiratory distress syndrome (ARDS) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced coronavirus disease 2019 (COVID-19) have not been elucidated.

MAIN TEXT

SARS-CoV-2 mainly targets the lungs and blood, leading to ARDS, and systemic thrombosis or bleeding. Angiotensin II-induced coagulopathy, SARS-CoV-2-induced hyperfibrin(ogen)olysis, and pulmonary and/or disseminated intravascular coagulation due to immunothrombosis contribute to COVID-19-associated coagulopathy. Type H ARDS is associated with hypoxemia due to diffuse alveolar damage-induced high right-to-left shunts. Immunothrombosis occurs at the site of infection due to innate immune inflammatory and coagulofibrinolytic responses to SARS-CoV-2, resulting in microvascular occlusion with hypoperfusion of the lungs. Lung immunothrombosis in type L ARDS results from neutrophil extracellular traps containing platelets and fibrin in the lung microvasculature, leading to hypoxemia due to impaired blood flow and a high ventilation/perfusion (VA/Q) ratio. COVID-19-associated ARDS is more vascular centric than the other types of ARDS. D-dimer levels have been monitored for the progression of microvascular thrombosis in COVID-19 patients. Early anticoagulation therapy in critical patients with high D-dimer levels may improve prognosis, including the prevention and/or alleviation of ARDS.

CONCLUSIONS

Right-to-left shunts and high VA/Q ratios caused by lung microvascular thrombosis contribute to hypoxemia in type H and L ARDS, respectively. D-dimer monitoring-based anticoagulation therapy may prevent the progression to and/or worsening of ARDS in COVID-19 patients.

New method for determining fibrinogen and FDP threshold criteria by artificial intelligence in cases of massive hemorrhage during delivery

AIM

To investigate the feasibility of a novel method using artificial intelligence (AI), in which the fibrinogen criterion was determined by the quantitative relation between the distributions of fibrin/fibrinogen degradation products (FDPs) and fibrinogen.

METHODS

A dataset of 154 deliveries comprising more than 2000 g of blood lost due to hemorrhage, excluding disseminated intravascular coagulation (DIC), among patients from eight national perinatal centers in Japan from 2011 to 2015 were obtained. The fibrinogen threshold criterion was identified by using the function that best fit the distributions of FDP as determined by AI. FDP production was described by differential equations using a dataset containing fibrinogen levels less than the fibrinogen criterion and solved numerically.

RESULTS

A fibrinogen level of 237 mg/dL as the threshold criterion was obtained. The FDP threshold criteria were 2.0 and 8.5 mg/dL for no coagulopathy and a failed coagulation system, respectively.

CONCLUSION

The fibrinogen threshold criterion for patients with massive hemorrhage excluding DIC at delivery were obtained by selecting the functions that best fit the distributions of FDP data by using AI.

Functional characterization of a slow and tight-binding inhibitor of plasmin isolated from Russell's viper venom

BACKGROUND

Snake venoms are rich in Kunitz-type protease inhibitors that may have therapeutic applications. However, apart from trypsin or chymotrypsin inhibition, the functions of most of these inhibitors have not been elucidated. A detailed functional characterization of these inhibitors may lead to valuable drug candidates.

METHODS

A Kunitz-type protease inhibitor, named DrKIn-II, was tested for its ability to inhibit plasmin using various approaches such as far western blotting, kinetic analyses, fibrin plate assay and euglobulin clot lysis assay. In addition, the antifibrinolytic activity of DrKIn-II was demonstrated in vivo.

RESULTS

DrKIn-II potently decreased the amidolytic activity of plasmin in a dose-dependent manner, with a global inhibition constant of 0.2nM. Inhibition kinetics demonstrated that the initial binding of DrKIn-II causes the enzyme to isomerize, leading to the formation of a much tighter enzyme-inhibitor complex. DrKIn-II also demonstrated antifibrinolytic activity in fibrin plate assay and significantly prolonged the lysis of the euglobulin clot. Screening of DrKIn-II against a panel of serine proteases indicated that plasmin is the preferential target of DrKIn-II. Furthermore, DrKIn-II treatment prevented the increase of FDP in coagulation-stimulated mice and significantly reduced the bleeding time in a murine tail bleeding model.

CONCLUSION

DrKIn-II is a potent, slow and tight-binding plasmin inhibitor that demonstrates antifibrinolytic activity both in vitro and in vivo.

GENERAL SIGNIFICANCE

This is the first in-depth functional characterization of a plasmin inhibitor from a viperid snake. The potent antifibrinolytic activity of DrKIn-II makes it a potential candidate for the development of novel antifibrinolytic agents.

Coagulofibrinolytic changes in patients with disseminated intravascular coagulation associated with post-cardiac arrest syndrome--fibrinolytic shutdown and insufficient activation of fibrinolysis lead to organ dysfunction

INTRODUCTION

Post-cardiac arrest syndrome (PCAS) is often associated with disseminated intravascular coagulation (DIC), thus leading to the development of multiple organ dysfunction syndrome (MODS). The aim of this study was to examine the pathophysiological relationships between coagulation, fibrinolysis and fibrinolytic shutdown by evaluating the levels of coagulofibrinolytic markers, including soluble fibrin, thrombin-activatable fibrinolysis inhibitor (TAFI), tissue plasminogen activator-plasminogen activator inhibitor-1 complex (tPAIC), plasmin-alpha2 plasmin inhibitor complex (PPIC), neutrophil elastase and fibrin degradation product by neutrophil elastase (EXDP).

MATERIALS AND METHODS

Fifty-two resuscitated patients were divided into two groups: 22 DIC and 30 non-DIC patients.

RESULTS

The levels of soluble fibrin, PPIC, tPAIC, EXDP and neutrophil elastase in the DIC patients with PCAS were significantly higher than those observed in the non-DIC patients. The values of the tPAIC and JAAM DIC scores were found to be independent predictors of increased SOFA scores in the DIC patients. The MODS patients demonstrated significantly higher levels of soluble fibrin and tPAIC; however, the levels of TAFI and EXDP were identical between the patients with and without MODS. In addition, positive correlations were observed between the levels of tPAIC and EXDP in the patients with non-MODS; however, no correlations were observed between these markers in the MODS patients.

CONCLUSIONS

Thrombin activation and fibrinolytic shutdown play important roles in the development of organ dysfunction in PCAS patients. Neutrophil elastase-mediated fibrinolysis cannot overcome the fibrinolytic shutdown that occurs in DIC patients with PCAS, thus resulting in the development of MODS.