Viscoelastic Coagulation Monitoring Research Articles

Platelet transfusion prior to major surgery in a thrombocytopenic dog

AbstractFresh platelet concentrate (FPC) is described as the product of choice for the control of bleeding due to severe thrombocytopenia and has recently become commercially available in the UK. We report a successful, prophylactic FPC transfusion when given in combination with tranexamic acid prior to fracture repair in a 4‐year‐old Whippet. The patient presented with right radial and ulnar fractures and severe thrombocytopenia (platelet count 23 × 109/L). Viscoelastic coagulation monitoring (VCM) revealed coagulopathy, with prolonged clot formation times, but other coagulation parameters were within normal limits. One unit (65 mL) of FPC was given pre‐operatively. The dog underwent surgery without excessive bleeding and experienced no complications. Post‐transfusion VCM showed improved clot formation and clot strength. Transfusion of FPC in combination with tranexamic acid increased this dog's ability to clot, suggesting that it is an effective perioperative therapy for severely thrombocytopenic patients requiring urgent surgery.

Feline aortic thromboembolism with and without congestive heart failure did not exhibit hypercoagulability using a novel viscoelastic coagulation monitor.

To demonstrate hypercoagulability with a benchtop viscoelastic monitor in cats with congestive heart failure (CHF) and/or aortic thromboembolism (ATE) compared to controls. 97 cats were enrolled throughout this prospective observational cohort study from September 2022 through October 2023. Cats were grouped by diagnosis of CHF, ATE, ATE plus CHF, or controls. Enrollment required diagnosis of heart disease and no previous antithrombotic therapy. The results of viscoelastic testing with the benchtop viscoelastic coagulation monitor (VCM Vet [VCM]; Entegrion) were compared between groups using factorial analysis of variance. Cats with heart disease had significantly higher clot times when compared to controls (control: mean, 285.3 [SD, 172.6]; CHF: mean, 391.7 [SD, 106.8]; ATE: mean, 415.9 [SD, 109.2]; and ATE plus CHF: mean, 368.6 [SD, 232.6]). Heart disease cats were noted to have significantly lower 45-minute lysis index values (control: median, 100 [range, 93 to 100]; CHF: median, 99 [range, 89 to 100]; ATE: median, 98 [range, 88 to 100]; and ATE plus CHF: range, 98 [91 to 100]). Age was a covariate to this variable, and when applied to analysis, statistical significance was lost. No significant difference in any other variables were noted. The hypercoagulability of ATE and CHF cats was not detected by the VCM. Further research with other coagulation monitors is required in this population.

Evaluation of clopidogrel response in healthy cats using a novel viscoelastic test and thromboelastography.

Cats with cardiomyopathy face an increased risk of arterial thromboembolism (ATE). Although clopidogrel is frequently utilized to mitigate this risk, feline responses to this therapy exhibit variability. This study evaluated 2 viscoelastic devices, thromboelastography (TEG) and Viscoelastic Coagulation Monitor (VCM), for monitoring clopidogrel in cats in comparison to light transmission aggregometry (LTA). Twenty-eight healthy cats received clopidogrel for 7 days. Blood was collected at baseline and after treatment for analysis by TEG, VCM, and LTA. On LTA, maximum amplitude, slope, and area under the curve (AUC) significantly decreased after treatment (p < 0.0001). On VCM, maximum clot firmness (MCF) significantly increased after treatment (p = 0.002). On TEG, R-time significantly prolonged (p = 0.024), while K and alpha angle significantly changed (p = 0.0002 and p = 0.0014, respectively). There was a moderate negative correlation between TEG R-time and LTA AUC (r = -0.39, p = 0.042). Eight cats were identified as non-responders to clopidogrel. Of the 8 non-responders, 6 (75%) had shortened R time after treatment. VCM appeared to be less discriminatory in identifying non-responders. LTA remained the gold standard of monitoring clopidogrel treatment in cats. Unexpected changes on VCM and TEG were likely related to high interindividual and assay variability and increased sensitivity of feline platelets. R-time on TEG may have potential utility for point-of-care monitoring of clopidogrel response in cats.

Point-of-care viscoelastic coagulation monitor parameters in Amazon parrots (Amazona spp.).

To evaluate the feasibility of the point-of-care viscoelastic coagulation monitor (VCM) in Amazon parrots (Amazona spp.) and describe the parameters with fresh whole-blood samples in healthy Amazon parrots. A total of 18 Amazon parrots were enrolled. Physical examinations, a CBC, and a biochemistry profile, including bile acids, were performed on all parrots. VCM tracings were obtained at the time of venipuncture for baseline laboratory work. The median clot time was 2102seconds (range: 38.6-3599s), median clot formation time was 929seconds (range: 21.4-1711s), median alpha angle was 20 (range: 6-67), and the median maximum clot formation was 8.5 (range: 0-36). The median lysis index at 30minutes (LI30) was 100 (range: 98-100), and the median lysis index at 45minutes (LI45) was 100 (range: 90-100). Of 18 samples, alpha angles were not reported in 7 samples, LI30 was not reported in 10 samples, and LI45 was not reported in 12 samples. Of the qualitative curves, 6 reflected normal mammalian curves, and the remainder were consistent with a hypocoaguable state. The results were markedly variable, with the majority of VCM tracings being hypocoagulable in comparison with reference intervals established for dogs and cats. Using these protocols, the VCM is not reliable in Amazon parrots. Future areas of investigation include altering the temperature during sample analysis, the use of activators, or an exchange of clotting reagents for an extrinsic pathway activator, which may contribute to the success of this device in avian species.

Viscoelastic coagulation monitoring parameters in cats with acute arterial thromboembolism.

Hypercoagulability has been documented in cats with cardiac disease. However, hemostatic parameters, including viscoelastic coagulation monitoring (VCM) have not been reported in cats with arterial thromboembolism (ATE). Compare VCM parameters in cats with acute cardiogenic ATE and in control cats. Sixteen cats with ATE and 30 control cats. Multicenter university-based prospective study. Cardiogenic ATE was diagnosed based on physical examination and by ultrasonographically-diagnosed left atrial enlargement. Viscoelastic coagulation monitor analysis, CBC, serum biochemistry profile and coagulation profile were performed at admission in cats with ATE. Analysis from healthy control cats was performed using blood collected by direct venipuncture. Our objective was comparison of VCM parameters clot time (CT), clot formation time (CFT), alpha angle (Angle), maximum clot formation (MCF), amplitude at 10 and 20 minutes (A10 and A20, respectively) and clot lysis index at 30 and 45 minutes (LI30 and LI45, respectively) between ATE and control cats. Cats with ATE had a decreased angle compared to control cats, with a median (range) of 43° (30-48°) compared to 47° (14-59°; P = .01). The parameters A10, A20 and MCF were decreased in ATE cats compared to control cats with a median (range) of 19 units (8-32) compared to 22 units (6-38), 24.5 units (11-40) compared to 29 units (10-47) and 29.5 units (13-44) compared to 33.5 units (14-53), respectively (P = .01, .01 and .01, respectively). The parameters CT, CFT, LI30 and LI45 were similar between groups (P = .22, .09, .62 and .34, respectively). Cats with cardiogenic ATE cats have VCM parameters consistent with hypocoagulability compared with healthy cats.

Assessment of hemostasis in hyperthyroid and euthyroid cats using two viscoelastic assays and platelet aggregometry.

Hyperthyroidism in humans is associated with a hypercoagulable state and an increased risk of thromboembolism. To evaluate hemostatic variables in hyperthyroid and euthyroid cats with the hypothesis that hyperthyroid cats will have evidence of altered hemostasis consistent with a potential hypercoagulable state. Client-owned hyperthyroid (n = 16) and euthyroid (n = 15) cats over 8 years of age. Prospective observational study. Hyperthyroid and euthyroid cats were enrolled. Rotational thromboelastometry (ROTEM), whole-blood platelet impedance aggregometry (WBPIA) and a point-of-care viscoelastic coagulation monitor (VCM-Vet) were performed immediately after minimally traumatic venipuncture under sedation. Hyperthyroid cats had significantly higher values for variables as assessed by VCM-Vet: A10 (34 [17-47] vs 25 [17-38], P = .003); A20 (39.5 [23-55] vs 31 [21-45], P = .003); and MCF (41 [24-58] vs 35 [22-49], P = .03). Hyperthyroid cats had significantly different values versus the euthyroid cohort as assessed by different ROTEM channels: increased A10, INTEM (61.5 [39-75] vs 54 [23-66], P = .007) and FIBTEM (18 [10-35] vs 13 [2-27], P = .01); increased A20, INTEM (68 [45-78] vs 61 [30-70], P = .006) and FIBTEM (17 [10-34] vs 11 [2-25], P = .002); increased MCF, EXTEM (72 [65-81] vs 69 [34-78], P = .04), INTEM (70 [45-85] vs 62 [35-71], P = .01) and FIBTEM (18 [13-37] vs 14 [3-27], P = .02); increased alpha angle, EXTEM (80 [68-85] vs 76 [41-84], P = .01); shortened CT, EXTEM (52.5 [29-73] vs 60 [52-92], P = .003) and FIBTEM (52.5 [16-75] vs 65 [53-165], P = .001); and decreased ML, FIBTEM (20 [1-36] vs 33 [19-59], P <.001). No significant differences were found with WBPIA. The hyperthyroid cats in this study had evidence of altered hemostasis as assessed by 2 viscoelastic methodologies, and characterized by increased clot amplitude, firmness, and faster coagulation times vs euthyroid controls.

INVESTIGATION OF A POINT-OF-CARE VISCOELASTIC COAGULATION MONITOR AND ITS COMPARISON TO THROMBOELASTOGRAPHY IN CLINICALLY HEALTHY AFRICAN ELEPHANTS (LOXODONTA AFRICANA).

Elephant endotheliotropic herpesvirus (EEHV) can induce fatal hemorrhagic disease (HD) in African elephants (Loxodonta africana). Once clinical signs develop, progression is rapid, even with aggressive treatment. There is a critical need to develop point-of-care diagnostic tests to aid in identification of EEHV-HD prior to the onset of overt clinical signs. Study objectives were to investigate a novel, point-of-care viscoelastic coagulation monitor (VCM Vet), compare the results to thromboelastography (TEG), and report traditional hemostatic analytes in adult African elephants. Whole blood was collected from seven clinically healthy elephants (four females and three males, 18-47 yr) and analyzed in duplicate via VCM Vet and kaolin-activated TEG 1-3 and 30 min following collection, respectively. Separated plasma was frozen for ancillary coagulation testing. Both analyses generated quantifiable clotting reactions with variables (median [range]) describing clot formation rate (VCM Vet, clot time = 682 s [530-987 s], clot formation time = 244 s [186-744 s], Alpha = 40° [14-47°]; TEG, reaction time = 6.2 min [3.7-11.8 min], kinetic time = 1.3 min [0.9-2.6 min], Alpha = 70° [57-77°]), clot strength (VCM Vet, maximum clot formation = 34 units [20-45 units]; TEG, maximum amplitude = 75 mm [69-80 mm], shear elastic modulus strength = 14.7 Kdynes/s [11.3-19.5 Kdynes/s]), and clot lysis (VCM Vet, lysis index at 30 min = 100% [100-99%], lysis index at 45 min = 98% [95-100%]; TEG, lysis index at 30 min = 0% [0-0.4%], lysis index at 60 min = 1.4% [0-2.6%]) recorded. Additional testing (median [range]) included D-dimer concentration (33 ng/ml [28-94 ng/ml]), prothrombin time (12.4 s [12.2-13.2 s]), activated partial thromboplastin time (17.2 s [14.2-18.8 s]), and fibrinogen concentration (297 [282-383] mg/dL). Tracings generated by VCM Vet and TEG were clinically similar, and there was visual agreement and minimal difference between quantitative variables for duplicate tests. VCM Vet is a promising, user-friendly tool for use in identification and management of coagulopathies in African elephants.

Evaluation of viscoelastic coagulation monitoring parameters and fibrinogen concentrations in healthy dogs undergoing stifle arthroscopy and tibial plateau leveling osteotomy.

Evaluation of viscoelastic parameters along with Hct percentages, platelet numbers, and fibrinogen concentrations in healthy dogs undergoing elective stifle arthroscopy and tibial plateau leveling osteotomy (TPLO). These results determine if dogs are in a normal, hypocoagulable, or hypercoagulable state at 4 different time points. Prospective study of 37 client-owned dogs enrolled between February 2, 2022, and November 10, 2022. All dogs received a standardized anesthetic protocol. Patients enrolled in the study underwent stifle arthroscopy using a 3-portal technique with a TPLO performed by board-certified surgeons. Viscoelastic testing, Hct percentage, fibrinogen concentration, and platelet numbers were measured preoperatively, immediately postoperatively, 24 hours postoperatively, and 14 days postoperatively. Stifle arthroscopy and TPLO surgery was not associated with significant effects on viscoelastic coagulation monitoring and fibrinogen concentrations in healthy dogs when comparing the time points. Humans have a high risk of thrombotic events when undergoing elective orthopedic surgery and are often placed on prophylactic antithrombotic medication prior to surgery. Viscoelastic coagulation monitoring in dogs undergoing similar orthopedic procedures has been evaluated in veterinary medicine, but the effects on platelets and fibrinogen concentrations from similar orthopedic procedures and uniform anesthesia protocols have not been documented. Cranial cruciate ligament insufficiency is the most common orthopedic injury in dogs. Treatment requires elective surgical correction for the best results and improved long-term prognosis. The findings of this study suggest that similar preoperative prophylactic antithrombotic intervention is not needed for canine patients.

Comparison of coagulation and fibrinolysis in Irish Wolfhounds and age-matched control dogs using tissue plasminogen activator-augmented viscoelastic testing.

To determine if Irish Wolfhounds (IWs), like other sighthounds, are hyperfibrinolytic compared with nonsighthound dogs using 2 native and tissue plasminogen activator (tPA)-enhanced viscoelastic assays, one that is whole blood-based (viscoelastic coagulation monitor [VCM]) and the other that is plasma-based thromboelastography (TEG). Cohort study. University teaching hospital. A convenience sample of 27 IWs recruited from the Irish Wolfhound Association of New England Specialty and the local community, and 27 healthy, age-matched, large-breed control dogs. None. Blood samples including CBC, biochemistry, traditional coagulation, and viscoelastic testing were collected from IWs and control dogs. Twelve IWs had viscoelastic testing. IWs had lower fibrinogen concentrations (215.5±57.8vs 251.4±64.5mg/dL, P=0.034) and formed weaker clots on both whole-blood VCM and plasma TEG assays (maximum clot firmness [VCM-MCF]=39.4 [25.1-48.8] vs 48.5 [34.6-57.3], P=0.0042; maximum amplitude [TEG-MA]=22.7 [14.7-33.6] vs 32.2 [26.9-42.0], P<0.0001). IWs were hyperfibrinolytic compared with control dogs on VCM whole-blood assays, with 25U/mL tPA (lysis at 30min [VCM-LI30]=68.1 [0-100] vs\ 99.9 [63.3-100], P=0.0009; lysis at 45min [VCM-LI45]=31.0 [0-100] vs 98.1 [38.4-100], P=0.0002) but hypofibrinolytic compared with controls on TEG plasma assays with 50U/mL tPA (lysis at 30min [TEG-LY30]=45.7 [4.6-94.6] vs 93.7 [12.3-96.5], P=0.0004; lysis at 60min [TEG-LY60]=68.7 [29.7-96.8] vs 95.7 [34.4-97.6], P=0.0003). Minimal fibrinolysis was measured on whole-blood VCM or plasma TEG assays without the addition of tPA, and there were no differences between the 2 groups. Weaker clots were found in IWs than control dogs. With the addition of tPA, IWs had evidence of hyperfibrinolysis on whole-blood VCM assays and hypofibrinolysis on plasma TEG assays compared with control dogs. Without the addition of tPA, however, both groups of dogs showed minimal fibrinolysis on viscoelastic testing.

Paying attention to the value of thrombelastography and the impact of postreperfusion syndrome on outcomes of liver transplantation.

Only limited information is available about the connection between massive blood transfusion and postoperative survival rates in pediatric liver transplantation. The aim of Gordon's study was to examine the potential impact of perioperative transfusion on postoperative complications and death in young children receiving pediatric living-donor liver transplantation (PLDLT). The authors concluded that transfusion of a red blood cell volume higher than 27.5 mL/kg during the perioperative period is associated with a significant increase in short- and long-term postoperative morbidity and mortality after PLDLT. However, viscoelastic coagulation monitoring was not utilized in the study; instead, only conventional coagulation monitoring was conducted. Overall, the choice of blood coagulation monitoring method during blood transfusion can have a significant impact on patient prognosis. Several studies have shown that the viscoelastic coagulation testing such as thrombelastography (TEG) is highly sensitive and accurate for diagnosing coagulation dysfunction. Indeed, a TEG-guided blood transfusion strategy can improve prognosis. Moreover, postreperfusion syndrome is one of the most common complications of liver transplantation and an important factor affecting the prognosis of patients and should also be included in regression analysis.

Coagulation management during liver transplantation: monitoring and decision making for hemostatic interventions.

Rebalanced hemostasis describes the precarious balance of procoagulant and antithrombotic proteins in patients with severe liver failure. This review is aimed to discuss currently available coagulation monitoring tests and pertinent decision-making process for plasma coagulation factor replacements during liver transplantation (LT). Contemporary viscoelastic coagulation monitoring systems have demonstrated advantages over conventional coagulation tests in assessing the patient's coagulation status and tailoring hemostatic interventions. There is increasing interest in the use of prothrombin complex and fibrinogen concentrates, but it remains to be proven if purified factor concentrates are more efficacious and safer than allogeneic hemostatic components. Furthermore, the decision to use antifibrinolytic therapy necessitates careful considerations given the risks of venous thromboembolism in severe liver failure. Perioperative hemostatic management and thromboprophylaxis for LT patients is likely to be more precise and patient-specific through a better understanding and monitoring of rebalanced coagulation. Further research is needed to refine the application of these tools and develop more standardized protocols for coagulation management in LT.

147: The Viscoelastic Coagulation Monitor (VCM) as a novel means for coagulation monitoring and adjustment in ECMO patients receiving bivalrudin: Initial results compared to the TEG 5000.

147: The Viscoelastic Coagulation Monitor (VCM) as a novel means for coagulation monitoring and adjustment in ECMO patients receiving bivalrudin: Initial results compared to the TEG 5000.

Preliminary evaluation of reference intervals for a point-of-care viscoelastic coagulation monitor (VCM Vet) in healthy adult horses.

To evaluate a point-of-care viscoelastic coagulation monitor (VCM Vet) for use in horses by assessing variability between devices and establish reference intervals (RIs) for healthy adult horses. Prospective observational study. Two university teaching hospitals. Healthy adult horses (n=68). None. Blood collected by direct jugular venipuncture was applied directly from the syringe into 2 VCM Vet cassettes to establish coefficients of variation (CVs) and RIs for reported parameters of clotting time (CT), clot formation time (CFT), alpha angle, amplitude at 10 and 20minutes, maximum clot firmness, and lysis index at 30 and 45minutes. CVs for each parameter were within clinical tolerance. There was a significant difference in CT between institutions (P<0.001). Differences in CV were found between institutions for CT (P=0.003) and CFT (P=0.01). Healthy horse RIs were calculated for the overall data set and each individual institution. Calculated RIs were as follows: CT, 255.6-1233.9seconds; CFT, 89.4-581seconds; alpha angle, 11.4-53.6°; maximum clot firmness, 18-37.7; lysis index at 30minutes, 97.3%-102.1%; lysis index at 45minutes, 80.8%-103.3%; amplitude at 10minutes, 8.7-28.3; and amplitude at 20minutes, 17.4-35.7. VCM Vet is a repeatable and practical option for rapid point-of-care assessment of hemostasis in horses but has a wide RI and is susceptible to variability. Establishment of institution-specific RIs is recommended.

Demonstration of hyperfibrinolysis on the VCM Vet in a dog with Angiostrongylus vasorum

AbstractThis case report details the clinical investigation of an 11‐month‐old, entire, male Cockapoo, who presented with acute left forebrain signs associated with suspected intra‐cranial haemorrhage due to Angiostrongylus vasorum. Initial investigations failed to identify a coagulopathy using traditional coagulation testing. Subsequent viscoelastic testing using the Viscoelastic Coagulation Monitor (VCM Vet, Entegrion) identified a hypocoagulable, hyperfibrinolytic trace. Anti‐fibrinolytic treatment with tranexamic acid showed improvement of hypocoagulability and normalisation of hyperfibrinolysis. Subsequent canine fresh frozen plasma transfusion and treatment of the underlying A. vasorum led to resolution of the patient's coagulopathy. This case report demonstrates the ease of use and utility of viscoelastic monitoring in global assessment of coagulation, and is the first case to document hyperfibrinolysis using the VCM Vet in a patient with Angiostrongylus vasorum.

Comparison of a viscoelastic point-of-care coagulation monitor with thromboelastography in sick dogs with hemostatic abnormalities.

Viscoelastic coagulation monitor (VCM-Vet) is a point-of-care device that has been used to characterize hemostatic abnormalities in sick pets but has not been validated in veterinary patients. We aimed to compare VCM-Vet and thromboelastography (TEG) in sick dogs with suspected disorders of hemostasis. Duplicate VCM-Vet tests using untreated native blood performed concurrently on two VCM-Vet machines, and simultaneous TEG tests were performed (one citrated native (CN), and one activated with tissue factor (TF) at a 1:3600 dilution). Each VCM-Vet result was compared with both TF-activated and CN TEG. Fifty-three dogs were enrolled. Eleven cases displayed apparent hyperfibrinolysis. Spearman correlation coefficients for individual VCM-Vet devices and CN and TF TEG were obtained between R and CT values and ranged from 0.21 to 0.27, CFT and K (r= 0.60-0.67), angles (r= 0.51-0.62), and MCF and MA (r= 0.85-0.87). Comparison of the two VCM-Vet devices displayed positive correlations for all clot formation parameters with Lin's concordance correlation coefficients of 0.75-0.95. Variable lysis parameter agreement existed between the VCM-Vet devices and VCM-Vet and TEG. When samples were classified as hypercoagulable or coagulopathic, VCM-Vet had a low positive predictive value (17-33%) for the detection of hypercoagulable states and a moderate negative predictive value (64-74%) for the detection of coagulopathy as defined by TEG. VCM-Vet and TEG had variable correlations in clot formation values and a strong correlation for final clot strength. More information is needed to make conclusions about the lysis parameters. Artifact in the fibrinolysis portion of the test can confound the interpretation of VCM-Vet results.

Evaluation of a Viscoelastic Coagulation Monitoring System (VCM Vet®) and Its Correlation with Thromboelastometry (ROTEM®) in Diseased and Healthy Dogs.

Thromboelastometry provides a real-time assessment of global coagulation in whole blood. A novel bed-side viscoelastic coagulation monitor (VCM) has been developed for use in small animals. The aims of the study were to determine inter-device agreement of two VCM devices, to evaluate the correlation between VCM and rotational thromboelastometry as a reference method (ROTEM), and to determine the sensitivity and specificity of VCM to diagnose hypo-, normo-, and hypercoagulability. ROTEM (extrinsic and intrinsic activation) analysis was performed using citrated blood and VCM analysis using native blood. Twenty healthy and forty diseased dogs with and without coagulopathies were enrolled. The VCM inter-device agreement was moderate to strong for most of the parameters, depending on the grading scale. Correlation between VCM and ROTEM was moderate to strong for parameters of clotting time and clot strength. The VCM most likely detects true hypocoagulability and reliably rules out hypocoagulability. The VCM has a high sensitivity in diagnosing normocoagulability, but incorrectly classified dogs with abnormal coagulation as normocoagulable. The VCM was not able to detect hypercoagulability. ROTEM and VCM cannot be used interchangeably.

Viscoelastic coagulation testing in Neonatal Intensive Care Units: advantages and pitfalls in clinical practice.

The expression "developmental hemostasis" indicates the age-related physiological changes occurring during the maturational process of the hemostatic system. Despite the quantitative and qualitative alterations, the neonatal hemostatic system is competent and well-balanced. Conventional coagulation tests do not provide reliable information as they only explore the procoagulants during the neonatal period. In contrast, viscoelastic coagulation tests (VCTs), such as viscoelastic coagulation monitoring (VCM), thromboelastography (TEG or ClotPro), and rotational thromboelastometry (ROTEM), are point-of-care assays that provide a quick, dynamic and global view of the hemostatic process, allowing prompt and individualized therapeutic intervention when necessary. Their use in neonatal care is on the increase and they could help monitor patients at risk of hemostatic derangement. In addition, they are crucial for anticoagulation monitoring during extracorporeal membrane oxygenation. Moreover, implementing VCT-based monitoring could optimize blood product use.

Effects of a single subcutaneous dose of enoxaparin on veterinary viscoelastic coagulation monitor variables in healthy cats: Double blind, placebo controlled cross-over trial.

Cats placed on anticoagulant medication require frequent monitoring. The veterinary viscoelastic coagulation monitor (VCM-Vet) could provide a convenient and cost-effective monitoring, enabling therapeutic decision making. Enoxaparin will lead to changes in VCM-Vet variables and these will correlate with antiXa activity. Twenty-one healthy cats. Cats were randomized to receive either enoxaparin (1mg/kg) subcutaneously or 0.9% NaCl (equal volume) and crossed over with a 7-day washout period. The investigators were blinded to group allocation until data analysis. Jugular blood samples were drawn at time 0, and 2, 4, and 8hours after injection for VCM-Vet analysis within 2min of collection. Citrated plasma was frozen at -80°C for antiXa activity analysis. A Generalized Linear Model was completed to assess changes between baseline measurements and all time points. Significant differences between the enoxaparin-treated cats and controls at for T0h and T2h were found and presented as mean ± SD for clotting time (enoxaparin, 593.4 ± 78.0s; control, 448.5 ± 50.3s, P < .001), clot formation time (enoxaparin, 183.1 ± 41.7s; control, 155.4 ± 28.0s, P=.001), and alpha angle (enoxaparin, 52.4 ± 6.1°; control, 56.9 ± 3.7s, P=.003). AntiXa activity was significantly different between T0 and all other timepoints for the enoxaparin group (P < .001). There was no correlation between changes in clotting time and antiXa activity. The VCM-Vet detects a difference at 2hours after single-dose enoxaparin administration and it can be useful for anticoagulant therapy monitoring in cats.

Point-of-care global coagulation assay parameters in normal dogs and dogs with primary immune-mediated hemolytic anemia.

To compare viscoelastic parameters between healthy control dogs and dogs with primary immune-mediated hemolytic anemia (pIMHA) using a new, point-of-care viscoelastic coagulation monitor (VCM).a DESIGN: Retrospective study from 2017 to 2021. Three regional private referral centers. Eighteen client-owned dogs with pIMHA and 33 healthy control dogs. pIMHA dogs were defined based on established criteria. None. Medical records of dogs with pIMHA and VCM performed at diagnosis from 2017 to 2021 and apparently healthy control dogs voluntarily enrolled in the blood donor program from 2017 to 2018 were reviewed. For the healthy control dogs, consent was obtained to perform VCM in addition to traditional screening. Compared to healthy control dogs, dogs with pIMHA had mean VCM parameters consistent with hypercoagulability, demonstrated by lower mean (SD) clot formation time (108 s [30] vs 233 s [55]; P<0.0001), higher mean alpha angle (62 degrees [6] vs 52 degrees [6]; P<0.0001), higher mean maximum clot formation (49 VCM units [11] vs 32 VCM units [5]; P<0.0001), higher mean amplitude at 10minutes (40 VCM units [11] vs 19 VCM units [3]; P<0.0001), and higher mean amplitude at 20minutes (47 VCM units [11] vs 25 VCM units [4]; P<0.0001). pIMHA dogs also had significantly higher median (interquartile range) lysis index at 30minutes (100% [100-100] vs 98% [90-100]; P<0.0001). When compared to 3 established normal canine reference intervals, dogs with pIMHA had a significantly higher proportion of VCM variables (48%-57%) consistent with hypercoagulability, and a significant percentage of pIMHA dogs (78%-89%) had VCM tracings consistent with hypercoagulability overall, irrespective of the interval utilized for interpretation. This study demonstrates hypercoagulability in dogs with pIMHA when compared to healthy control dogs using VCM. Prospective evaluation is warranted to further characterize these findings as well as to evaluate their clinical impact.

Point-of-care viscoelastic coagulation assessment in healthy dogs during the perianesthetic period

BackgroundThe viscoelastic coagulation monitor (VCM Vet) is a novel, portable device that provides a global assessment of hemostasis. The study aims were to evaluate serial viscoelastic analysis during the perianesthetic period in healthy dogs and to compare the agreement between two VCM Vet devices. Twenty healthy dogs undergoing orthopedic surgery were enrolled. Whole blood samples were collected from an intravenous catheter at four time points: baseline, 15 min after premedication, 60 min after inhalant initiation, and 60 min after inhalant termination. Viscoelastic tests were performed in duplicate on different devices, providing: clot time (CT; seconds), clot formation time (CFT; seconds), alpha angle (α; degrees), amplitude (units) at 10 (A10) and 20 (A20) minutes post clot time, maximum clot firmness (MCF; units), and lysis index (%) at 30 (Li30) and 45 (Li45) minutes post maximum clot formation.ResultsOne hundred sixty samples were analyzed. The speed of CT and CFT significantly decreased an average of 25.5 s (95% confidence interval [CI]15.9–35.0) and 6.9 s (95% CI 3.1–10.7) per time point, respectively. There were no significant changes in clot strength or lysis variables. The Bland–Altman style plot shows an acceptable rate of agreement for all variables with intra-class correlation ranging from 0.64–0.94.ConclusionThe rate of clot formation (CT and CFT) decreased over the perianesthetic period in healthy dogs undergoing surgery. These changes were small and occurred without changes in clot strength or fibrinolysis rate, thus were not clinically relevant. There was clinically acceptable consistency between devices.