Comparison of thromboelastography versus conventional coagulation tests in simulated Crotalus atrox envenomation using human blood

In vitro evaluation of canine whole blood with the addition of Crotalus atrox (Western Diamondback Rattlesnake) venom and antivenom using thromboelastography

OBJECTIVES

To compare the efficacy of 2 equine-origin antivenom products on correction of coagulation abnormalities noted on thromboelastography (TEG) caused by Crotalus atrox venom in vitro.

DESIGN

Prospective in vitro controlled study.

SETTING

Veterinary teaching hospital.

ANIMALS

Six healthy dogs.

INTERVENTIONS

Blood from each dog was used for 4 separate kaolin-activated TEG analyses: A negative control (blood-saline) and positive control (blood-Crotalus atrox venom) were used to assess the dog's normal coagulation and the effect of venom on TEG parameters. Thromboelastographic analyses were then run with blood, venom, and either Argentinian or North American antivenom. All TEG analyses from each dog were compared for efficacy.

MEASUREMENTS AND MAIN RESULTS

The mean R values between the North American antivenom and negative controls were not significantly different (P = 0.681), but were significantly different (P = 0.024) between the Argentinian antivenom and negative controls. The mean fibrinolysis values measured 30 minutes after maximum amplitude achieved between the North American antivenom and negative controls were not significantly different (P = 0.198), but were significantly different (P < 0.001) between the Argentinian antivenom and negative controls. The mean K values between the Argentinian antivenom and negative controls were not significantly different (P = 0.274), but were significantly different (P = 0.043) between the North American antivenom and negative controls.

CONCLUSIONS

The North American antivenom normalized time to clot formation and fibrinolysis, while the Argentinian antivenom normalized rate of clot formation. Further studies in naturally envenomated patients are necessary to determine if these in vitro results would translate into different clinical outcomes.

Hemostatic Analysis of Simulated Gloydius ussuriensis Envenomation Using Canine Blood: A Comparison of Thromboelastography and Classical Coagulation Tests

Snake envenomation may lead to venom-induced consumptive coagulopathy (VICC), usually diagnosed by classical coagulation tests (CCTs), such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). However, the results of CCTs are frequently normal in the initial stages, which may delay anti-venom treatments. Thromboelastography (TEG) is a point-of-care and real-time diagnostic tool that enables a comprehensive assessment of the coagulation process. This in vitro study aimed to determine concentration-dependent changes in canine blood caused by Gloydius ussuriensis (G. ussuriensis) envenomation using TEG and CCTs. Lyophilized G. ussuriensis venom was reconstructed using mouse intravenous lethal dose 50 (LD50iv) and serially diluted to 25% LD50iv, 50% LD50iv, and 75% LD50iv to reproduce VICC at different concentrations. Normal saline was used for the control. We compared TEG values of the reaction time (R), kinetic time (K), rate of clot formation (α-angle), maximum amplitude (MA), fibrinolysis at 30 min (LY30), and global strength of the clot (G) with those of PT, aPTT, fibrinogen, and platelet counts (PLTs). Most TEG parameters, except R and LY30, demonstrated statistically significant changes compared with the control at all concentrations. CCTs, except PLTs, revealed significant changes at ≥50% LD50iv. Thus, TEG could be a useful diagnostic strategy for early VICC and preventing treatment delay.

Gender Differences do not Influence the Blood Coagulopathy in Patients Undergoing Total Knee Arthroplasty: A Retrospective Thromboelastography Analysis

Objective

Deep vein thrombosis (DVT) is one of the severe complications after total knee arthroplasty (TKA). Gender has been considered to influence the incidence of the thrombosis formation in TKA patients. However, it remains controversial which gender would be more prone to form thrombosis. The aim of this study was to assess the effects of gender differences on coagulation status after TKA via the thromboelastography (TEG).

Methods

A total of 57 male patients who underwent primary TKA from September 2015 to January 2021 were included in this study. According to the matching principle of age, body mass index (BMI), and anticoagulation treatment, 60 female patients were selected. The conventional coagulation tests, routine blood tests, and thromboelastography were conducted before the operation, 1 day and 7 days after the operation. In addition, Doppler ultrasound was also performed 1 day before the operation and at the 7 days after the operation. The parameters of conventional coagulation tests, routine blood tests, and thromboelastography were compared between the two groups.

Results

There were no significant differences in the blood transfusion rate, the incidence of DVT during the perioperative period, D-dimer (D-D), fibrin degradation products (FDP), hemoglobin (HB), hematocrit (HCT), prothrombin time (PT), activated partial thromboplastin time (APTT), and C-reactive protein (CRP) at any corresponding time point between the male group and the female group (P > .05). There were no significant differences in neutrophil-to-lymphocyte ratio (NLR) preoperatively; however, there were significant differences in NLR 1 day after the surgery and 7 days after the surgery between the two groups (P < .05). There were significant differences in reaction time (R) and α angle 1 day after the surgery between the two groups (P < .05), but there were no significant differences in other TEG indexes at any corresponding time point between the two groups (P > .05). Binary logistic regression analysis demonstrated that gender, age, BMI, tourniquet application time were not independent predictors (P > .05).

Conclusion

Gender differences have no significant influence in TKA patients with regard to conventional coagulation tests and thromboelastography.

Novel Treatment Strategy for Patients with Venom-Induced Consumptive Coagulopathy from a Pit Viper Bite

Pit viper venom commonly causes venom-induced consumptive coagulopathy (VICC), which can be complicated by life-threatening hemorrhage. VICC has a complex pathophysiology affecting multiple steps of the coagulation pathway. Early detection of VICC is challenging because conventional blood tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT) are unreliable for early-stage monitoring of VICC progress. As the effects on the coagulation cascade may differ, even in the same species, the traditional coagulation pathways cannot fully explain the mechanisms involved in VICC or may be too slow to have any clinical utility. Antivenom should be promptly administered to neutralize the lethal toxins, although its efficacy remains controversial. Transfusion, including fresh frozen plasma, cryoprecipitate, and specific clotting factors, has also been performed in patients with bleeding. The effectiveness of viscoelastic monitoring in the treatment of VICC remains poorly understood. The development of VICC can be clarified using thromboelastography (TEG), which shows the procoagulant and anticoagulant effects of snake venom. Therefore, we believe that TEG may be able to be used to guide hemostatic resuscitation in victims of VICC. Here, we aim to discuss the advantages of TEG by comparing it with traditional coagulation tests and propose potential treatment options for VICC.