Insights into the association between coagulopathy and inflammation: abnormal clot mechanics are a warning of immunologic dysregulation following major injury

The role of inflammation and antithrombin supplementation on thromboelastographic parameters during veno-venous ECMO for respiratory failure

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO) may act as a driver or propagator of systemic inflammation. In turn, cytokine release can modify thromboelastographic (TEG) tests which are commonly used for anticoagulation monitoring. In this context, antithrombin (AT) supplementation might further modify TEG.

METHODS

This is a pre-specified sub-study of the "Randomized Controlled Trial of Antithrombin Supplementation During Extracorporeal Membrane Oxygenation" study (investigator-initiated, randomized, single-blind, two-arm trial) conducted in two Italian ECMO referral ICUs. Adult patients requiring vv-ECMO for respiratory failure and undergoing unfractioned heparin (UFH) administration were enrolled and randomized whether to receive AT supplementation. Plasma samples for cytokine assay (IL-8, IL-10, IL-6, IL-1β, TNF-α and Pro-ADM) and heparinase TEG were collected from every patient before ECMO start, 24 h and 72 h after ECMO start, before ECMO removal, and 7 days after ECMO removal or upon ICU discharge whichever happened first. AT concentration, coagulation and clinical data were collected before ECMO start and at pre-fixed time points.

RESULTS

Thirty-nine patients were enrolled (21 treatments, 18 controls). TEG-R had a weak-to-moderate positive correlation with IL-8, IL-6, IL-10 and TNF-α and a moderate positive correlation with Pro-ADM. TEG-ANG showed a weak negative correlation with IL-8, IL-6 and TNF-α, while TEG-MA negatively correlated with IL-8, TNF-α and Pro-ADM. AT supplementation seemed to modify the association between TEG-MA and IL-8, IL-10 and Pro-ADM; conversely, AT did not affect the relationship among TEG-R or TEG-ANG and the studied cytokines.

CONCLUSIONS

High concentrations of systemic cytokines correlated with longer reaction times and decreased angle and amplitude at TEG, suggesting that an increase in inflammation is related with hypocoagulability as revealed by thromboelastography.

A novel melanocortin fusion protein inhibits fibrinogen oxidation and degradation during trauma-induced coagulopathy

Immune cell inflammation is implicated in the pathophysiology of acute trauma-induced coagulopathy (TIC). We hypothesized that leukocyte inflammation contributes to TIC through the oxidation and proteolysis of fibrinogen. To test this hypothesis, antioxidants and a novel anti-inflammatory melanocortin fusion protein (AQB-565) were used to study the effects of interleukin-6 (IL-6)-stimulated human leukocytes on fibrinogen using single-cell imaging flow cytometry and multiplex fluorescent western blotting. We also studied the effects of AQB-565 on fibrinogen using an in vivo rat trauma model of native TIC. IL-6 induced cellular inflammation and mitochondrial superoxide production in human monocytes, causing fibrinogen oxidation and degradation in vitro. Antioxidants suppressing mitochondrial superoxide reduced oxidative stress and inflammation and protected fibrinogen. AQB-565 decreased inflammation, inhibited mitochondrial superoxide, and protected fibrinogen in vitro. Trauma with hemorrhagic shock increased IL-6 and other proinflammatory cytokines and chemokines, selectively oxidized and degraded fibrinogen, and induced TIC in rats in vivo. AQB-565, given at the onset of hemorrhage, blocked inflammation, protected fibrinogen from oxidation and degradation, and prevented TIC. Leukocyte activation contributes to TIC through the oxidation and degradation of fibrinogen, which involves mitochondrial superoxide and cellular inflammation. Suppression of inflammation by activation of melanocortin pathways may be a novel approach for the prevention and treatment of TIC.

Admission maximum amplitude-reaction time ratio: Association between thromboelastography values predicts poor outcome in injured children

INTRODUCTION

Thromboelastography (TEG)-derived maximum amplitude-reaction time (MA-R) ratio that accounts for both hypocoagulable and hypercoagulable changes in coagulation is associated with poor outcomes in adults. The relationship between these TEG values and outcomes has not been studied in children.

METHODS

In a retrospective cohort study, a level I pediatric trauma center database was queried for children younger than 18 years who had a TEG assay on admission between 2016 and 2020. Demographics, injury characteristics, and admission TEG values were recorded. The MA-R ratio was calculated and divided into quartiles. Main outcomes included mortality, transfusion within 24 hours of admission, and thromboembolism. A logistic regression model was generated adjusting for age, Injury Severity Score, injury mechanism, admission shock, and Glasgow Coma Scale.

RESULTS

In total, 657 children were included, of which 70% were male and 75% had blunt mechanism injury. The median (interquartile range) age was 11 (4-14) years, the median (interquartile range) Injury Severity Score was10 (5-22), and in-hospital mortality was 7% (n = 45). Of these patients, 17% (n = 112) required transfusion. Most R and MA values were within normal limits. On unadjusted analysis, the lowest MA-R ratio quartile was associated with increased mortality (15% vs. 4%, 5%, and 4%, respectively; p < 0.001) and increased transfusion need (26% vs. 12%, 16%, and 13%, respectively; p = 0.002) compared with higher quartiles. In the logistic regression models, a low MA-R ratio was independently associated with increased in-hospital mortality (odds ratio [95% confidence interval], 4.4 [1.9-10.2]) and increased need for transfusion within 24 hours of admission (odds ratio [95% confidence interval], 2.0 [1.2-3.4]) compared with higher MA-R ratio. There was no association between MA-R ratio and venous thromboembolic events (venous thromboembolic event rate by quartile: 4%, 2%, 1%, and 3%).

CONCLUSION

Although individual admission TEG values are not commonly substantially deranged in injured children, the MA-R ratio is an independent predictor of poor outcome. Maximum amplitude-reaction time ratio may be a useful prognostic tool in pediatric trauma; validation is necessary.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

Variations in clot phenotype following injury: The MA-R ratio and fragile clots

INTRODUCTION

Trauma-induced coagulopathy is a continuum ranging from hypercoagulable to hypercoagulable phenotypes. In single-center studies, the maximum amplitude (MA) to r-time (R) (MA-R) ratio has identified a phenotype of injured patients with high mortality risk. The purpose of this study was to determine the relationship between MA-R and mortality using multicenter data and to investigate fibrinogen consumption in the development of this specific coagulopathy phenotype.

METHODS

Using the Pragmatic Randomized Optimal Platelet and Plasma Ratios data set, patients were divided into blunt and penetrating injury cohorts. MA was divided by R time from admission thromboelastogram to calculate MA-R. MA-R was used to assess odds of early and late mortality using multivariable models. Multivariable models were used to assess thrombogram values in both cohorts. Refinement of the MA-R cut point was performed with Youden index. Repeat multivariable analysis was performed with a binary CRITICAL and NORMAL MA-R.

RESULTS

In initial analysis, MA-R quartiles were not associated with mortality in the penetrating cohort. In the blunt cohort, there was an association between low MA-R and early and late mortality. A refined cut point of 11 was identified (CRITICAL: MA-R, ≤11; NORMAL: MA-R, >11). CRITICAL MA-R was associated with mortality in both penetrating and blunt subgroups. In further injury subgroup analysis, CRITICAL patients had significantly decreased fibrinogen levels in the blunt subgroup only. In both blunt and penetrating injury, there was no difference in time to initiation of thrombin burst (lagtime). However, both endogenous thrombin potential and peak thrombin levels were significantly lower in CRITICAL patients.

CONCLUSIONS

MA-R identifies a trauma-induced coagulopathy phenotype characterized in blunt injury by impaired thrombin generation that is associated with early and late mortality. The endotheliopathy and tissue factor release likely plays a role in the cascade of impaired thrombin burst, possible early fibrinogen consumption and the weaker clot identified by MA-R.

LEVEL OF EVIDENCE

Therapeutic/care management, level II.