Hirudin versus citrate as an anticoagulant for ROTEM platelet whole blood impedance aggregometry in thrombocytopenic patients.

Citrate is widely used as an anticoagulant for platelet function tests (PFTs). Due to an intrinsic inhibitory effect of citrate on platelet function, hirudin is used as an alternative. However, studies comparing the effect of these anticoagulants on rotational thromboelastometry (ROTEM) platelet whole blood impedance aggregometry in thrombocytopenic patients are scant. Cross-sectional study was done in 105 patients who entered the critical phase of Dengue hemorrhagic fever with plasma leakage and severe thrombocytopenia (<100 × 109/L). Samples were collected on two consecutive days and considered as a combined data set for analysis, out of which 200 have been included in the data analysis. Platelet count was used from routine full blood count. ROTEM platelet used TRAPTEM assay, which was performed with 3.2% sodium citrate and 525 ATU/ml hirudin anticoagulated blood. Means of all the TRAPTEM parameters were significantly higher in hirudin, compared to citrate samples (p < .05). Significantly higher overall platelet aggregation was observed in hirudinized samples with a significant mean difference (p < .05) compared to citrate in each quartile of platelet count. Higher platelet aggregation was observed with hirudin compared to citrate in ROTEM platelet whole blood impedance aggregometry in thrombocytopenic patients elaborating the importance of using hirudin anticoagulation in PFTs, particularly in patients with severe thrombocytopenia.

Citrate is the most commonly used anticoagulant for coagulation studies including rotational thromboelastometry (ROTEM).Hirudin is an alternative option to be used as an anticoagulant for PFTs because of the inhibitory effect of citrate on platelet function.One study (Nissen et al. (2020)) reported higher precision and platelet aggregation with hirudinized blood of healthy individuals, over citrate using ROTEM platelet.However, none of the studies were performed in patients in actual clinical context.We evaluated the potential benefit of using hirudin anticoagulated blood over citrate in thrombocytopenic patients due to Dengue hemorrhagic fever using ROTEM platelet.We observed higher platelet aggregation with hirudin compared to citrate suggesting the importance of using hirudin anticoagulation in PFTs, particularly in patients with severe thrombocytopenia.

The use of rotational thromboelastometry parameters in understanding the coagulopathy following hump-nosed viper (Hypnale spp) bites: a preliminary study.

BACKGROUND: Hump-nosed vipers (HNV; Hypnale spp) are one of the medically important venomous snakes in Sri Lanka and South-Western regions of India. The haemostatic dysfunction due to HNV bites is poorly characterized by standard diagnostic tests performed to identify coagulopathy. We aimed to determine the usefulness of rotational thromboelastometry (ROTEM) parameters compared to 20-minute whole blood clotting test (WBCT20) and prothrombin time (PT) in understanding the coagulopathy of HNV bites. METHODS: Twenty-three HNV snakebite patients in a prospective study of 127 consecutive snakebites were recruited. After recording details of the clinical presentation, PT/international normalized ratio (INR), WBCT20 and ROTEM delta were performed at presentation. RESULTS: In this preliminary study, none of the patients had clinically apparent bleeding. Coagulopathy was detected by either WBCT20, INR or ROTEM in 13 HNV patients. Eleven had a coagulopathy detectable by ROTEM (either abnormal EXTEM-CT, INTEM-CT or FIBTEM-MCF) but with negative WBCT20. Of them, only two had prolonged INR values. Two patients had positive WBCT20 but with normal ROTEM and INR values. The remaining 10 patients did not show any coagulopathy either by INR, ROTEM or WBCT20. CONCLUSION: In this preliminary study with small number of sample size, ROTEM parameters appeared to be more sensitive to subtle changes in coagulation compared to WBCT20. The clinical utility of detecting these changes and their usefulness in managing snakebite should be explored further in a larger study.

Rotational thromboelastometry in critical phase of dengue infection: Association with bleeding.

Background: The critical phase of dengue carries a high risk of bleeding. Associations of coagulation test parameters and the risk of bleeding in the critical phase is unclear. This study examines the association of rotational thromboelastometry (ROTEM delta and ROTEM platelet) with bleeding risk of patients with dengue in the critical phase. Methods: A total of 105 patients with confirmed dengue in the critical phase were recruited, with two subsequent prospective time point analyses of ROTEM parameters and platelet count within 24 and 48 hours from the onset of the critical phase. Conventional coagulation tests were performed only at the initial time point. Results: Twenty of 105 patients developed bleeding after onset of the critical phase. Within the first 24 hours of critical-phase onset, platelet count, coagulation tests, and ROTEM delta were unable to differentiate patients with bleeding manifestations from those without (P < .05). Area under the curve of thrombin receptor activating peptide-6 assay of ROTEM platelet (TRAPTEM) discriminated patients with bleeding manifestations from those without, at a cutoff value of <12.5 Ω*min at a sensitivity and specificity of 73.7%, and 60.2%. In patients who developed bleeding, the maximum lysis of extrinsic pathway of ROTEM was significantly lower in patients with severe bleeding compared to those with mild to moderate bleeding. (4.3 ± 3.4% vs 9.4 ± 7.5%; P = .01). Conclusion: An association with bleeding manifestations and TRAPTEM suggest a potential role for defective platelet aggregation in the pathogenesis of bleeding in the critical phase of dengue.

Pharmacokinetic, pharmacodynamic, and pharmacogenetic assays to monitor clopidogrel therapy.

Clopidogrel is the most common and widely used antiplatelet agent for patients with coronary artery disease following confirmation by electrocardiographic studies. The nonresponsiveness of patients to clopidogrel and the possibility of testing for clopidogrel resistance by platelet function assays (PFA) are contentious issues. Light transmission aggregometry (LTA) is considered as the gold standard test among all PFA. In this review, the most commonly used PFA used for monitoring the effect of clopidogrel, LTA, vasodilator-stimulated phosphoprotein assay phosphorylation, rotational thromboelastometry (ROTEM) delta and ROTEM platelet, thromboelastography, PFA-100, VerifyNow P2Y12 assay, Multiplate analyzer, Plateletworks assay and pharmacogenetic studies, are comparatively discussed including their principles of action, advantages, and disadvantages. VerifyNow P2Y12 assay can be accepted as the ideal point of care test out of the discussed assays. However, modified assays are required which could overcome the limitations associated with currently available assays.

A study of association between platelet volume indices and ST elevation myocardial infarction.

INTRODUCTION AND OBJECTIVE: ST elevation myocardial infarction (STEMI) is caused by formation of a thrombus at a ruptured atheromatous plaque. Larger platelets are enzymatically and metabolically more active and play a crucial role in thrombus formation. Our objective was to study the association between platelet volume indices (mean platelet volume (MPV) and platelet distribution width (PDW)) and STEMI. METHODS: A hospital-based case control study to compare the platelet indices of 52 STEMI patients before commencing antiplatelet therapy and age and gender matched 52 controls who had no history of ischemic heart disease or antiplatelet therapy. Blood samples were collected to EDTA bottles and analyzed using Mindray BC 6800 automated analyzer. RESULTS: STEMI patients had significantly increased mean MPV and PDW compared to the control group ((8.22 ±â€¯0.99 fL vs 7.74 ±â€¯0.69 fL, p = 0.005) and (15.81 ±â€¯0.41 fL vs 15.62 ±â€¯0.33 fL, p = 0.007) respectively). Significant positive correlation existed between MPV and PDW (R = 0.556, p = 0.000) and weak negative correlation in platelet count with MPV (R = -0.323, p = 0.019) and PDW (R = -0.309, p = 0.026) of STEMI patients. Receiver Operating Characteristic (ROC) curves showed that MPV and PDW with cutoff values of 7.55 fL, 15.55 fL and with Area under the curve (AUC) of 0.640, 0.620 respectively. The sensitivities and specificities were found to be 73.1%, 69.2% and 61.5%, 55.8% for MPV and PDW respectively. CONCLUSION: Increased MPV and PDW were found to have a significant association with STEMI and this test has the potential to be used as a preliminary test to identify high-risk patient for myocardial infarction.