Instability of the non-activated rotational thromboelastometry assay (NATEM) in citrate stored blood

Persistent hypofibrinolysis in severe COVID-19 associated with elevated fibrinolysis inhibitors activity

Hypercoagulability and reduced fibrinolysis are well-established complications associated with COVID-19. However, the timelines for the onset and resolution of these complications remain unclear. The aim of this study was to evaluate, in a cohort of COVID-19 patients, changes in coagulation and fibrinolytic activity through ROTEM assay at different time points during the initial 30 days following the onset of symptoms in both mild and severe cases. Blood samples were collected at five intervals after symptoms onset: 6-10 days, 11-15 days, 16-20 days, 21-25 days, and 26-30 days. In addition, fibrinogen, plasminogen, PAI-1, and alpha 2-antiplasmin activities were determined. Out of 85 participants, 71% had mild COVID-19. Twenty uninfected individuals were evaluated as controls. ROTEM parameters showed a hypercoagulable state among mild COVID-19 patients beginning in the second week of symptoms onset, with a trend towards reversal after the third week of symptoms. In severe COVID-19 cases, hypercoagulability was observed since the first few days of symptoms, with a tendency towards reversal after the fourth week of symptoms onset. A hypofibrinolytic state was identified in severe COVID-19 patients from early stages and persisted even after 30 days of symptoms. Elevated activity of PAI-1 and alpha 2-antiplasmin was also detected in severe COVID-19 patients. In conclusion, both mild and severe cases of COVID-19 exhibited transient hypercoagulability, reverted by the end of the first month. However, severe COVID-19 cases sustain hypofibrinolysis throughout the course of the disease, which is associated with elevated activity of fibrinolysis inhibitors. Persistent hypofibrinolysis could contribute to long COVID-19 manifestations.

Comprehensive comparison of global coagulation assays to differentiate lupus anticoagulant from acquired hemophilia A in patients with prolonged APTT

There is no established method for differentiating acquired hemophilia A (AHA) from lupus anticoagulant (LA) positivity because both present with prolonged activated partial thromboplastin time. We compared various parameters of rotational thromboelastometry (ROTEM), thrombin generation assay (TGA), and clot waveform analysis (CWA) in patients with AHA (n = 10) and LA (n = 44). Compared with AHA, possible (n = 12) and definite (n = 32) LA showed significantly shorter clotting time (CT) in NATEM mode of ROTEM (> 3600 vs. 501/533). In TGA, peak height was significantly lower in AHA (16 vs. 242/174 nM). In CWA, CT was significantly longer (81 vs. 36/41 s) and Ad|min1| was lower (2.1 vs. 8.7/6.7) in AHA. Notably, CT by NATEM and peak height in TGA completely discriminated between AHA and LA, whereas Ad|min1| did not discriminate between them in 4 cases of AHA and 1 of LA. Comparison of 3 patients with both AHA and LA against a patient with only LA and markedly low FVIII activity (3.5%) showed that both CT by NATEM and peak height of TGA precisely classified the former 3 cases as AHA and the latter 1 case as LA, whereas Ad|min1| classified all 4 cases as AHA. ROTEM and TGA can comparably distinguish between AHA and LA.

Assessment of agreement between EXTEM and NATEM thromboelastometry measurement assays in critically ill neonates

OBJECTIVES

To investigate the agreement between the EXTEM and NATEM measurements.

METHODS

In this retrospective observational study, EXTEM and NATEM analyses were performed on blood samples from 162 ill neonates, providing 324 paired measurements. The agreement between EXTEM and NATEM measurements was evaluated by the nonparametric spearman's rank correlation to assess the correlation between the paired measurements, by the Bland-Altman analysis for the graphical presentation of the agreement, and by the Deming regression model to assess the significance of the agreement. The agreement between the two methods for the detection of bleeding events was determined by kappa statistic.

RESULTS

Strong correlations were found between EXTEM and NATEM measurements for A10, MCF. The Bland-Altman plots showed good agreement for A10, MCF, LI60, and alpha angle parameters, while CT showed a nearly linear slope indicating that bias increased with the mean. The highest agreement for bleeding events was found for the A10 parameter (κ = 0.70, p < .001), while the lowest for the CT parameter (κ = 0.36, p = .94).

CONCLUSIONS

NATEM parameters that reflect clot firmness and fibrinolytic activity are strongly correlated with the corresponding EXTEM measurements with a good agreement between them, indicating that these two methods could be used interchangeably.

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.

The Non-Activated Thromboelastometry (NATEM) Assay's Application among Adults and Neonatal/Pediatric Population: A Systematic Review

The non-activated thromboelastometry (NATEM) assay is a point-of-care assay that can provide a comprehensive insight into the actual hemostatic mechanism. However, there are very limited data about its use in clinical practice. The aim of this study was to systematically review the literature for any data regarding the use of NATEM in several clinical settings. A systematic review of PubMed and Scopus databases was conducted through 20 January 2022 for studies evaluating the use of the NATEM assay in different clinical settings. The literature search yielded a total of 47 publications, 30 of which met the eligibility criteria for this review. Evaluation of NATEM’s detecting ability for hemostasis disorders is limited in the literature. The results of the included studies indicate that NATEM seems to be a sensitive method for the detection of hyperfibrinolysis and may have an advantage in the diagnosis of hemostatic disorders. It could be more informative than the other ROTEM assays for detecting changes in coagulation parameters in patients who receive anticoagulants. However, the reported outcomes are highly varying among the included studies. NATEM has a high sensitivity to detect hypo- or hypercoagulability and provides a detailed insight into the whole hemostatic process from clot formation to clot breakdown. It could be a useful technique in variable fields of medicine, not only in adults, but also in pediatric and neonatal populations, to guide different hemostatic treatments and predict coagulation disorders or mortality/morbidity; this issue remains to be further investigated.

"In Less than No Time": Feasibility of Rotational Thromboelastometry to Detect Anticoagulant Drugs Activity and to Guide Reversal Therapy

Anticoagulant drugs (i.e., unfractionated heparin, low-molecular-weight heparins, vitamin K antagonists, and direct oral anticoagulants) are widely employed in preventing and treating venous thromboembolism (VTE), in preventing arterial thromboembolism in nonvalvular atrial fibrillation (NVAF), and in treating acute coronary diseases early. In certain situations, such as bleeding, urgent invasive procedures, and surgical settings, the evaluation of anticoagulant levels and the monitoring of reversal therapy appear essential. Standard coagulation tests (i.e., activated partial thromboplastin time (aPTT) and prothrombin time (PT)) can be normal, and the turnaround time can be long. While the role of viscoelastic hemostatic assays (VHAs), such as rotational thromboelastometry (ROTEM), has successfully increased over the years in the management of bleeding and thrombotic complications, its usefulness in detecting anticoagulants and their reversal still appears unclear.

Baseline parameters for non-activated rotational thromboelastometry tests with and without heparinase in healthy pregnant women at term gestation

OBJECTIVE

To determine the normal values for non-activated thromboelastometry parameters among pregnant women.

DESIGN

Prospective, observational study.

SETTING

Tertiary care hospital.

PATIENTS

Non-laboring women at term gestation without history of bleeding or clotting disorder or anticoagulation use.

INTERVENTIONS

Venous blood samples were collected and ROTEM® was performed using NATEM and NaHEPTEM assays.

MEASUREMENTS

Reference ranges were derived by calculating 2.5 and 97.5 percentiles for the following parameters: clotting time (CT), clot formation time (CFT), amplitude at 10 (A10) and 20 min (A20), alpha angle, maximum clot firmness (MCF), and lysis index at 30 (LI30) and 60 min (LI60). The NATEM/NaHEPTEM CT ratio was calculated to determine the baseline ratio in term pregnant women.

MAIN RESULTS

146 women were screened and 120 were enrolled. The median age was 34 years [31-36], median gestational age was 39.1 weeks [38.3-39.3], and median parity was 1 [0-2]. Median pre-delivery platelet and hematocrit levels were within the normal ranges. The reference ranges for NATEM parameters were: CT (232-759 (s)), CFT (69-243 (s)), alpha angle (50-77 (°)), A10 (44-69 (mm)), A20 (54-75 (mm)), MCF (57-77 (mm)), LI30 (100-100 (%)), LI60 (90-100 (%)). The reference ranges for NaHEPTEM parameters were: CT (224-717 (s)), CFT (66-210 (s)), alpha angle (53-77 (°)), A10 (44-67 (mm)), A20 (55-73 (mm)), MCF (58-74 (mm)), LI30 (99-100 (%)), LI60 (90-100 (%)). The NATEM to NaHEPTEM CT ratio reference range was 0.73-1.3.

CONCLUSIONS

This study is the first to our knowledge to report reference ranges for non-activated ROTEM® tests with and without heparinase in non-laboring term pregnant women. These reference ranges may serve as a baseline comparison and may be useful for future research on anticoagulation management in pregnancy.