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

Hemostatic Status of Neonates with Perinatal Hypoxia, Studied via NATEM in Cord Blood Samples

BACKGROUND

Perinatal hypoxia may result in coagulation dysfunction. Diminished blood flow or oxygen to the fetus/neonate during the perinatal period can cause bone marrow and liver function impairment, leading to thrombocytopenia, impaired synthesis of clotting and fibrinolytic factors, and increased destruction of platelets in the small blood vessels. The goal of the present study was to evaluate the hemostatic status of newborns with perinatal hypoxia via the non-activated thromboelastometry (NATEM) assay in cord blood samples.

METHODS

134 hypoxic neonates born in our maternity unit over a 1.5-year period were enrolled in this observational cohort study, and 189 healthy neonates served as the control group. Participation in the study was voluntary and parents signed informed consent prior to recruitment. Demographic and clinical data were recorded on admission, and the NATEM method was performed on cord blood samples. The following NATEM values were evaluated: clotting time (CT), alpha angle (α-angle), clot formation time (CFT), clot amplitude at 5 and 10 min. (A5, A10), maximum clot firmness (MCF), clot lysis index at 60 min. after CT (LI60), and maximum clot elasticity (MCE). Statistical analysis was conducted utilizing the SAS for Windows 9.4 software platform.

RESULTS

Neonates with perinatal hypoxia exhibited decreased fibrinolytic potential in comparison to healthy neonates, as indicated by increased LI60, and this difference was statistically significant (LΙ60: 94 (92-96) Vs 93 (91-95), p value = 0.0001). There were no statistically significant differences noted among the remaining NATEM variables.

CONCLUSION

Our findings indicate decreased fibrinolytic potential in hypoxic neonates in comparison to healthy neonates, suggesting that NATEM could serve as an effective tool for promptly identifying hemostasis dysfunction in this group of neonates.

Assessment of Hemostatic Profile in Neonates with Intrauterine Growth Restriction: A Systematic Review of Literature

Intrauterine growth restriction (IUGR) affects nearly 10 to 15% of pregnancies and is responsible for many short- and long-term adverse consequences, including hemostatic derangement. Both thrombotic and hemorrhagic events are described in the perinatal period in these neonates. The aim of this study was to systematically review the literature on the laboratory studies used to evaluate the hemostatic system of the IUGR small for gestational age neonate. We reviewed the current literature via PubMed and Scopus until September 2022. Following our inclusion/exclusion criteria, we finally included 60 studies in our review. Thrombocytopenia, characterized as hyporegenerative and a kinetic upshot of reduced platelet production due to in utero chronic hypoxia, was the main finding of most studies focusing on growth-restricted neonates, in most cases is mild and usually resolves spontaneously with the first 2 weeks of life. In regard to coagulation, growth-restricted newborns present with prolonged standard coagulation tests. Data regarding coagulation factors, fibrinolytic system, and anticoagulant proteins are scarce and conflicting, mainly due to confounding factors. As thromboelastography/rotational thromboelastometry (TEG/ROTEM) provides a more precise evaluation of the in vivo coagulation process compared with standard coagulation tests, its use in transfusion guidance is fundamental. Only one study regarding TEG/ROTEM was retrieved from this population, where no difference in ROTEM parameters compared with appropriate for gestational age neonates was found. Despite the laboratory aberrations, no correlation could be achieved with clinical manifestations of bleeding or thrombosis in the studies included. More studies are needed to assess hemostasis in IUGR neonates and guide targeted therapeutic interventions.

The Proteome of Extracellular Vesicles Released from Pulmonary Microvascular Endothelium Reveals Impact of Oxygen Conditions on Biotrauma

The lung can experience different oxygen concentrations, low as in hypoxia, high as under supplemental oxygen therapy, or oscillating during intermittent hypoxia as in obstructive sleep apnea or intermittent hypoxia/hyperoxia due to cyclic atelectasis in the ventilated patient. This study aimed to characterize the oxygen-condition-specific protein composition of extracellular vesicles (EVs) released from human pulmonary microvascular endothelial cells in vitro to decipher their potential role in biotrauma using quantitative proteomics with bioinformatic evaluation, transmission electron microscopy, flow cytometry, and non-activated thromboelastometry (NATEM). The release of vesicles enriched in markers CD9/CD63/CD81 was enhanced under intermittent hypoxia, strong hyperoxia and intermittent hypoxia/hyperoxia. Particles with exposed phosphatidylserine were increased under intermittent hypoxia. A small portion of vesicles were tissue factor-positive, which was enhanced under intermittent hypoxia and intermittent hypoxia/hyperoxia. EVs from treatment with intermittent hypoxia induced a significant reduction of Clotting Time in NATEM analysis compared to EVs isolated after normoxic exposure, while after intermittent hypoxia/hyperoxia, tissue factor in EVs seems to be inactive. Gene set enrichment analysis of differentially expressed genes revealed that EVs from individual oxygen conditions potentially induce different biological processes such as an inflammatory response under strong hyperoxia and intermittent hypoxia/hyperoxia and enhancement of tumor invasiveness under intermittent hypoxia.

Hemostatic Profile of Intrauterine Growth-Restricted Neonates: Assessment with the Use of NATEM Assay in Cord Blood Samples

BACKGROUND

Intrauterine growth restriction (IUGR) is associated with hemorrhagic and thrombotic complications during the perinatal period. Thrombocytopenia, platelet dysfunction, and prolonged standard coagulation tests are observed in this population. The aim of this study is to examine the hemostatic profile of IUGR neonates with the use of a non-activated assay (NATEM) in cord blood samples.

METHODS

During an 18 month period, a NATEM ROTEM assay was performed on cord blood samples of 101 IUGR neonates. A total of 189 appropriate for gestational age (AGA) neonates were used as a control group. The NATEM variables recorded include the following: clotting time (CT); clot formation time (CFT); clot amplitude at 5, 10, and 20 min (A5, A10, A20); α-angle (a°); maximum clot firmness (MCF); lysis index at 30 and 60 min (LI30, LI60); and maximum clot elasticity (MCE).

RESULTS

IUGR neonates demonstrate a hypocoagulable state, with lower A5, A10, A2, MCF, and MCE values when compared to AGA. Using multiple linear regression, we determined IUGR as an independent factor influencing all NATEM parameters (except CT and LI30) exhibiting a hypocoagulable and hypofibrinolytic profile. Platelet count was positively correlated with A5, A10, A20, MCF, alpha angle, and MCE, and negatively correlated with CFT.

CONCLUSION

IUGR neonates appear with lower clot strength and elasticity and prolonged clot kinetics, as illustrated by ROTEM variables.

Hemostatic capability of ultrafiltrated fresh frozen plasma compared to cryoprecipitate

This in vitro study evaluated the potential hemostatic effect of fresh frozen plasma (FFP) ultrafiltration on clotting factors, coagulation parameters, and plasma properties. ABO-specific units of FFP (n = 40) were prepared for the concentrated FFP and cryoprecipitate. Plasma water was removed from FFP by ultrafiltration using a dialyzer with a pump running at a 300 mL/min. The aliquot of each concentrated FFP after 50, 100, 200, and 250 mL of fluid removal were measured the standard coagulation assay, clotting activity, and plasma properties to compare those parameters of cryoprecipitate. Concentrated FFP contained 36.5% of fibrinogen in FFP with a mean concentration of 7.2 g/L, lower than the cryoprecipitate level. The levels of factor VIII (FVIII), von Willebrand factor (VWF):antigen (Ag), and VWF:ristocetin cofactor (RCo) were also lower in concentrated FFP, whereas the levels of factor V, factor IX, factor XIII, antithrombin and albumin was higher in concentrated FFP. Maximum clot firmness (MCF) in thromboelastometry was approximately one-half of that in cryoprecipitate. Although the levels of VWF:Ag, VWF:RCo, and FVIII differed depending on the ABO blood types, fibrinogen levels, and MCF were not significantly different among the ABO blood groups in FFP and concentrated FFP.

Sepsis Induced Coagulopathy: Bringing Science to the Bedside

How to cite this article: Samavedam S, Sepsis Induced Coagulopathy: Bringing Science to the Bedside. Indian J Crit Care Med 2023;27(9): 611-612.

Rotational Thromboelastometry (ROTEM®) in Relation to Inflammatory Biomarkers and Clinical Outcome in COVID-19 Patients

Background: The pathogenesis of hypercoagulability in COVID-19 patients is complex and not fully understood. Rotational thromboelastometry (ROTEM^®) is a viscoelastic method that allows the definition of a patient's hemostatic profile. This study aimed to assess the relationship between ROTEM^® parameters, the profile of inflammatory cytokines, and clinical outcomes in COVID-19 patients. Methods: A total of 63 participants (n = 29 symptomatic non-ICU COVID-19 patients, and n = 34 healthy controls) were prospectively included in the study. We assessed the relationship between the parameters of three ROTEM^® tests (NATEM^®, EXTEM^®, and FIBTEM^®) and levels of CRP, interleukin-8, interleukin-1β, interleukin-6, interleukin-10, tumor necrosis factor, interleukin 12p70, and clinical outcomes. Results: ROTEM^® indicated hypercoagulability in COVID-19 patients in all the tests performed. The levels of all inflammatory cytokines were significantly higher in COVID-19 patients. NATEM more frequently detected hypercoagulability in COVID-19 patients compared to EXTEM. The strongest correlations with inflammatory biomarkers and CT severity score were with FIBTEM parameters. The elevated maximum clot elasticity (MCE) in FIBTEM was the strongest predictor of poor outcomes. Conclusions: Increased FIBTEM MCE may be associated with greater severity of COVID-19. Non-activated ROTEM (NATEM test) seems to be more valuable for detecting hypercoagulability in COVID-19 patients compared to the tissue factor activated test (EXTEM).

The Utility of NATEM Assay in Predicting Bleeding Risk in Critically Ill Neonates

We aimed to investigate the hemostatic status of diseased neonates using nonactivated rotational thromboelastometry (ROTEM) assay (NATEM) assay and, in addition, to evaluate the discriminative power of NATEM parameters in predicting the risk of bleeding in critically ill neonates and compare it to that of EXTEM (extrinsically activated ROTEM) parameters. This cohort study included 158 consecutive, critically ill neonates with presumed sepsis, perinatal hypoxia, or respiratory distress syndrome. The EXTEM and NATEM assays were performed on the first day of disease onset. The neonatal bleeding assessment tool was used to record and assess clinical bleeding events on the day of ROTEM analysis. Several EXTEM and NATEM ROTEM parameters differed between neonates with and without clinical bleeding events, indicating a hypo-coagulable state in neonates with clinical bleeding. NATEM parameters had comparable predictive performance for clinical bleeding events with EXTEM parameters for clotting time, clot formation time (CFT), A10 (clot amplitude at 10minutes), maximum clot firmness, lysis index at 60minutes, and maximum clot elasticity (p>0.05). However, NATEM A20, A30, and α angle demonstrated better predictive ability than EXTEM A20, A30, and α angle, respectively (p<0.05). A NATEM CFT value ≥147seconds presented 95.2% sensitivity (95% confidence interval [CI]: 76.1-99.8%) and 65.6% specificity (95% CI: 57.1-73.5%) to detect neonates with clinical bleeding, while a NATEM A10 value ≤42mm had 80.8% sensitivity (95% CI: 71.8-85.9%) and 76.0% specificity (95% CI: 52.8-91.7%) to detect neonates with clinical bleeding events. The NATEM assay has shown remarkable sensitivity in predicting bleeding in critically ill neonates, exceeding EXTEM performance in some selected parameters. The incorporation of NATEM test parameters in predictive models for neonatal hemorrhage seems promising.

Sepsis-Induced Coagulopathy: An Update on Pathophysiology, Biomarkers, and Current Guidelines

Significant cross talk occurs between inflammation and coagulation. Thus, coagulopathy is common in sepsis, potentially aggravating the prognosis. Initially, septic patients tend to exhibit a prothrombotic state through extrinsic pathway activation, cytokine-induced coagulation amplification, anticoagulant pathways suppression, and fibrinolysis impairment. In late sepsis stages, with the establishment of disseminated intravascular coagulation (DIC), hypocoagulability ensues. Traditional laboratory findings of sepsis, including thrombocytopenia, increased prothrombin time (PT) and fibrin degradation products (FDPs), and decreased fibrinogen, only present late in the course of sepsis. A recently introduced definition of sepsis-induced coagulopathy (SIC) aims to identify patients at an earlier stage when changes to coagulation status are still reversible. Nonconventional assays, such as the measurement of anticoagulant proteins and nuclear material levels, and viscoelastic studies, have shown promising sensitivity and specificity in detecting patients at risk for DIC, allowing for timely therapeutic interventions. This review outlines current insights into the pathophysiological mechanisms and diagnostic options of SIC.

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.