Succinate Activation of SUCNR1 Predisposes Severely Injured Patients to Neutrophil-mediated ARDS.

OBJECTIVES: Identify the metabolites that are increased in the plasma of severely injured patients that developed ARDS versus severely injured patients that did not, and assay if these increased metabolites prime pulmonary sequestration of neutrophils (PMNs) and induce pulmonary sequestration in an animal model of ARDS. We hypothesize that metabolic derangement due to advanced shock in critically injured patients leads to the PMNs, which serves as the first event in the ARDS. Summary of Background Data: Intracellular metabolites accumulate in the plasma of severely injured patients. METHODS: Untargeted metabolomics profiling of 67 critically injured patients was completed to establish a metabolic signature associated with ARDS development. Metabolites that significantly increased were assayed for PMN priming activity in vitro. The metabolites that primed PMNs were tested in a 2-event animal model of ARDS to identify a molecular link between circulating metabolites and clinical risk for ARDS. RESULTS: After controlling for confounders, 4 metabolites significantly increased: creatine, dehydroascorbate, fumarate, and succinate in trauma patients who developed ARDS ( P < 0.05). Succinate alone primed the PMN oxidase in vitro at physiologically relevant levels. Intravenous succinate-induced PMN sequestration in the lung, a first event, and followed by intravenous lipopolysaccharide, a second event, resulted in ARDS in vivo requiring PMNs. SUCNR1 inhibition abrogated PMN priming, PMN sequestration, and ARDS. Conclusion: Significant increases in plasma succinate post-injury may serve as the first event in ARDS. Targeted inhibition of the SUCNR1 may decrease ARDS development from other disease states to prevent ARDS globally.

28-day thawed plasma maintains α2 -antiplasmin levels and inhibits tPA-induced fibrinolysis.

INTRODUCTION: Evidence supports the use of plasma-first resuscitation in the treatment of trauma-induced coagulopathy (TIC). While thawed plasma (TP) has logistical benefits, the ability of plasma proteins to attenuate fibrinolysis and correct TIC remain unknown. We hypothesize that TP retains the ability to inhibit tissue plasminogen activator(tPA)-induced fibrinolysis at 28-day storage. METHODS: Healthy volunteers underwent blood draws followed by 50% dilution of whole blood (WB) with TP at 28-, 21-, 14-, 7-, 5-, and, 0-day storage, normal saline (NS), and WB control. Samples underwent citrated tPA-challenge (75 ng/ml) thromboelastography (TEG). Plasminogen activator inhibitor-1 (PAI-1) and α2 -antiplasmin (α2 -AP) concentrations in thawed or stored plasma were determined. RESULTS: In the presence of tPA, 28-day TP inhibited tPA-induced coagulopathy as effectively as WB. 28-day TP had a similar R-time, MA, and fibrinolysis (P > 0·05 for all) compared to WB, while angle was enhanced (P = 0·02) compared to WB. Significant correlations were present between storage time and clot strength (P = 0·04) and storage time and fibrinolysis (P = 0·0029). Active PAI-1 levels in thawed plasma were 1·10 ± 0·54 ng/mL while total PAI-1 levels were 4·79 ± 1·41 ng/mL. There was no difference of α2 -AP levels in FFP (40·45 ± 3·5 µg/mL) compared to plasma thawed for 14 (36·78 ± 5·39 µg/mL, P = 0·65) or 28 days (45·16 ± 5·61 µg/mL, P = 0·51). DISCUSSION: Thawed plasma retained the ability to inhibit tPA-induced fibrinolysis over 28-day storage at 1-4°C. α2 -AP levels were maintained in plasma thawed for 28 days and FFP. These in vitro results suggest consideration should be made to increasing the storage life of TP.

Effects of Blood Components and Whole Blood in a Model of Severe Trauma-Induced Coagulopathy.

BACKGROUND: Plasma resuscitation ameliorates hyperfibrinolysis (HF) and trauma-induced coagulopathy (TIC). However, the use of other blood components to reduce HF has not been evaluated. Therefore, our aim was to determine the effect of individual blood components and whole blood (WB) on an in vitro model of severe HF/TIC. METHODS: A "TIC" solution was made with 1:1 dilution of WB with saline and exacerbated with tissue plasminogen activator (tPA). Components were added in proportions equivalent to the thromboelastography (TEG) based goal-directed resuscitation used at our institution. Whole blood was added at proportions equal to what has been transfused in injured patients. Samples (n = 9) underwent citrated native and tPA-challenge (75 ng/mL) TEG with analysis of R-time, angle, MA, and LY30. Statistical analyses were completed employing the nonparametric Kruskal-Wallis and Dunn's multiple comparisons tests. RESULTS: TIC solution, when compared to control, had a decrease in clot strength (MA 41 mm versus 51.5 mm, P < 0.01). The addition of tPA resulted in a severe coagulopathy (MA 24.5 mm versus 41 mm and LY30 52.8% versus 2.4%, P < 0.03 for all). The addition of 4U of WB improved clot strength compared to TIC + tPA (P = 0.03). No individual blood component resulted in improved fibrinolysis (P > 0.7). Cryoprecipitate improved R-time (7.5 versus 11.9 min, P < 0.01), angle (56.8 versus 30.2°) and MA (49 mm versus 36.25 mm), while platelets improved MA (44 mm versus 36.25 mm) compared to TIC + tPA (P < 0.03 for all). CONCLUSIONS: No single blood component or volume of whole blood led to attenuation of tPA-mediated fibrinolysis in an in vitro model of TIC. Cryoprecipitate was the most effective at improving coagulation function.

Rotational thromboelastometry thresholds for patients at risk for massive transfusion.

BACKGROUND: Goal-directed hemostatic resuscitation based on thrombelastography has a survival benefit compared to conventional coagulation assays. While thrombelastography transfusion thresholds for patients at risk for massive transfusion (MT) have been defined, similar cutoffs do not exist for the other commonly used viscoelastic assay, rotational thromboelastometry (ROTEM). The purpose of this study was to develop ROTEM blood product thresholds in patients at risk for MT. METHODS: ROTEM was assessed in trauma activation patients admitted from 2010 to 2016 (n = 222). Receiver operating characteristic curve analyses were performed to test the predictive performance of ROTEM measurements in patients requiring MT. The Youden Index defined optimal thresholds for ROTEM-based resuscitation. RESULTS: Patients who required MT (n = 37, 17%) were more severely injured. EXTEM clotting time (CT) was longer in patients with MT compared to non-MT (87 versus 64 s, P < 0.0001). EXTEM angle was shallower in MT patients compared to non-MT (54° versus 69°, P < 0.0001). Clot amplitude after 10 min (CA10) was less in MT compared to non-MT patients (30.5 versus 50 mm, P < 0.0001). Clot lysis index 60 min (CLI60) was lower in patients who had MT than non-MT (47 versus 94%, P = 0.0006). EXTEM CT yielded an area under the receiver operating characteristic curve (AUROC) = 0.7116 and a cut point of >78.5 s. EXTEM angle had an AUROC = 0.865 and a cut point of <64.5°. EXTEM CA10 had an AUROC = 0.858, with a cut point of <40.5 mm. CLI60 had an AUROC = 0.6788 with a cut point at <74%. CONCLUSIONS: We have identified ROTEM thresholds for transfusion of blood components in severely injured patients requiring an MT. Based on our analysis, we propose plasma transfusion for EXTEM CT > 78.5 s, fibrinogen for angle <64.5°, platelet transfusion for CA10 < 40.5 mm, and antifibrinolytics for CLI60 < 74%.

Trauma and hemorrhagic shock activate molecular association of 5-lipoxygenase and 5-lipoxygenase-Activating protein in lung tissue.

BACKGROUND: Post-traumatic lung injury following trauma and hemorrhagic shock (T/HS) is associated with significant morbidity. Leukotriene-induced inflammation has been implicated in the development of post-traumatic lung injury through a mechanism that is only partially understood. Postshock mesenteric lymph returning to the systemic circulation is rich in arachidonic acid, the substrate of 5-lipoxygenase (ALOX5). ALOX5 is the rate-limiting enzyme in leukotriene synthesis and, following T/HS, contributes to the development of lung dysfunction. ALOX5 colocalizes with its cofactor, 5-lipoxygenase-activating protein (ALOX5AP), which is thought to potentiate ALOX5 synthetic activity. We hypothesized that T/HS results in the molecular association and nuclear colocalization of ALOX5 and ALOX5AP, which ultimately increases leukotriene production and potentiates lung injury. MATERIALS AND METHODS: To examine these molecular interactions, a rat T/HS model was used. Post-T/HS tissue was evaluated for lung injury through both histologic analysis of lung sections and biochemical analysis of bronchoalveolar lavage fluid. Lung tissue was immunostained for ALOX5 and ALOX5AP with association and colocalization evaluated by fluorescence resonance energy transfer. In addition, rats undergoing T/HS were treated with MK-886, a known ALOX5AP inhibitor. RESULTS: ALOX5 levels increase and ALOX5/ALOX5AP association occurred after T/HS, as evidenced by increases in total tissue fluorescence and fluorescence resonance energy transfer signal intensity, respectively. These findings coincided with increased leukotriene production and with the histological changes characteristic of lung injury. ALOX5/ALOX5AP complex formation, leukotriene production, and lung injury were decreased after inhibition of ALOX5AP with MK-886. CONCLUSIONS: These results suggest that the association of ALOX5/ALOX5AP contributes to leukotriene-induced inflammation and predisposes the T/HS animal to lung injury.

Tranexamic acid is associated with increased mortality in patients with physiological fibrinolysis.

BACKGROUND: Tranexamic acid (TXA) administration after trauma has not been proven to improve survival in the United States. Trauma patients were presented to the hospital with a spectrum of fibrinolytic activity, in which physiological levels of fibrinolysis are associated with the lowest mortality. We hypothesize that trauma patients who present to the hospital with physiological levels of fibrinolysis will have increased mortality if they receive TXA. MATERIALS AND METHODS: Severely injured trauma patients, followed prospectively from 2014 to 2016, were included in the analysis. The patient's first thrombelastography was used to stratify patients into fibrinolysis phenotypes which included fibrinolysis shutdown, physiological fibrinolysis, and systemic hyperfibrinolysis. The primary outcome was in-hospital mortality. RESULTS: A total of 232 patients were analyzed (11% received TXA) with an overall mortality rate of 20%. TXA administration was associated with a higher new injury severity score (49 versus 28; P = 0.001), massive transfusion rate (69% versus 12%; P < 0.001), and mortality (52% versus 17%; P < 0.001). Hyperfibrinolysis and shutdown had higher mortality rates than physiological group (24% versus 30% versus 14%; P = 0.050). The effect of TXA within phenotypes was not significant for shutdown (28% versus 38%; P = 0.604) but was significant in the physiological group (11% versus 63%; P < 0.001) and systemic hyperfibrinolysis (19% versus 55%; P = 0.023). After adjusting for new injury severity score, TXA remained a significant predictor of mortality for patients with physiological fibrinolysis (P = 0.018). CONCLUSIONS: There was no clear benefit of receiving TXA in this study, and patients who present to the hospital with physiologic levels of fibrinolysis, who received TXA, had the highest mortality. The role of TXA in mature trauma systems remains unclear, and emerging data supports it may have adverse effects.

14-Day thawed plasma retains clot enhancing properties and inhibits tPA-induced fibrinolysis.

BACKGROUND: Plasma-first resuscitation attenuates trauma-induced coagulopathy (TIC); however, the logistics of plasma-first resuscitation require thawed plasma (TP) be readily available due to the obligatory thawing time of fresh frozen plasma (FFP). The current standard is storage of TP for up to 5 days at 4°C, based on factor levels at outdate, for use in patients at risk for TIC, but there remains a 2.2% outdated wastage rate. However, the multitude of plasma proteins in attenuating TIC remains unknown. We hypothesize that TP retains the ability to enhance clotting and reduce tPA-induced fibrinolysis at 14-day storage. METHODS: FFP was thawed and stored at 4°C at the following intervals: 14, 10, 7, 5, 3, and 1-day prior to the experiment. Healthy volunteers underwent blood draws followed by 50% dilution with TP stored at previously mentioned intervals as well as FFP, normal saline (NS), albumin, and whole blood (WB) control. Samples underwent tPA-modified (75 ng/mL) thrombelastography (TEG) with analysis of R-time, angle, maximum amplitude (MA), and LY30. RESULTS: TEG properties did not change significantly over the thawed storage. 14-day TP retained the ability to inhibit tPA-induced hyperfibrinolysis (median LY30% 9.6%) similar to FFP (5.6%), WB (14.6%), and superior to albumin (59.3%) and NS (58.1%). 14-day TP also retained faster clot formation (median angle, 66.2°) and superior clot strength (MA, 61.5 mm) to albumin (34.8°, 21.6 mm) and NS (41.6°, 32.2 mm). CONCLUSIONS: TP plasma stored for 14 days retains clot-enhancing ability and resistance to clot degradation similar to FFP. A clinical trial is needed to validate these in vitro results.

Thrombelastography indicates limitations of animal models of trauma-induced coagulopathy.

BACKGROUND: Thrombelastography (TEG) has been used to characterize the coagulation changes associated with injury and shock. Animal models developed to investigate trauma-induced coagulopathy (TIC) have failed to produce excessive bleeding. We hypothesize that a native TEG will demonstrate marked differences in humans compared with these experimental models, which explains the difficulties in reproducing a clinically relevant coagulopathy in animal models. METHODS: Whole blood was collected from 138 healthy human volunteers, 25 swine and 66 Sprague-Dawley rats before experimentation. Citrated native TEGs were conducted on each whole blood sample within 2 h of collection. The clot initiation (R-time, minutes), angle (degrees), maximum amplitude (MA; millimeter), and lysis 30 min after MA (LY30; percentage) were analyzed and contrasted between species with data represented as the median and 25th to 75th quartile range. Difference between species was conducted with a Kruskal-Wallis test with alpha adjusted with a Bonferroni correction for multiple comparisons (alpha = 0.016). RESULTS: Median R-time (clot initiation) was 14.65 min (IQR: 13.2-16.3 min) for humans, 5.7 min (4.9-8.8) for pigs, and 5.2 min (4.4-6) for rodents. Humans had longer R-times than both pigs (P < 0.0001) and rats (P < 0.0001); pigs were not different from rats (P = 0.4439). Angle (fibrin cross-linking) was 42.3° (interquartile range [IQR]: 37.5-50.2) for humans, 71.7° (64.3-75.6) for pigs, and 61.8° (56.8-66.7) for rats. Humans had reduced angle compared with both pigs (P < 0.0001) and rats (P < 0.0001); pigs were not different from rats (P = 0.6052). MA (clot strength) was 55.5 mm (IQR: 52.0-59.5) for humans, 72.5 mm (70.4-75.5) for pigs, and 66.5 mm (56.5-68.6) for rats. Humans had reduced MA compared with both pigs (P < 0.0001) and rats (P < 0.0001); pigs were not different from rats (P = 0.0161). LY30 (fibrinolysis) was 1.5% (IQR: 0.975-2.5) for humans, 3.3% (1.9-4.3) for pigs, and 0.5% (0.1-1.2) for rats. Humans had a lesser LY30 than pigs (P = 0.0062) and a greater LY30 than rats (P < 0.0001), and pigs had a greater LY30 than rats (P < 0.0001). CONCLUSIONS: Humans, swine, and rodents have distinctly different coagulation systems, when evaluated by citrated native TEG. Animals are hypercoagulable with rapid clotting times and clots strengths nearly 50% stronger than humans. These coagulation differences indicate the limitations of previous models of trauma-induced coagulopathy in producing coagulation abnormalities associated with increased bleeding. The inherent hypercoagulable baseline tendencies of these animals may result in subclinical biochemical changes that are not detected by conventional TEG and should be taken into consideration when extrapolated to clinical medicine.

Do not drink and lyse: alcohol intoxication increases fibrinolysis shutdown in injured patients.

INTRODUCTION: High alcohol consumption has been associated with decreased fibrinolysis and enhanced thrombosis risk in cardiovascular disease. In trauma, alcohol has been associated with poor clot formation; however, its effect on fibrinolysis has not been fully investigated. We assessed the association of blood alcohol levels and fibrinolysis in trauma activation patients. METHODS: We queried our prospective registry of trauma activations from 2014 to 2016. Associations between viscoelastic measurements [rapid thrombelastography (rTEG)] and blood alcohol level (BAL) were determined and adjusted for confounders by a multinomial logistic regression. Lysis phenotypes were defined by the % lysis in 30 min (LY30) as follows: hyperfibrinolysis ≥ 3%, physiologic 0.9-2.9%, and fibrinolysis shutdown < 0.9%. RESULTS: Overall, 191 (43.8%) had BAL measured. There were 65 (34%) patients that had no detectable BAL, 32 (16.8%) had BAL of 10-150 mg/dL, and 94 (49.2%) patients had BAL > 150 mg/dL. BAL had a moderate, but significant inverse correlation with LY30 (Rho = - 0.315, p < 0.001), while there were no significant correlations between BAL and other TEG values. The distribution of fibrinolysis phenotypes varied significantly by BAL levels (p < 0.009, with high BAL having more shutdown and less hyperfibrinolysis than the other two BAL level groups. Multinomial logistic regression showed that after adjustment for confounders, BAL levels > 150 mg/dL were independently associated with a threefold increase in the odds of shutdown compared to undetectable BAL (OR 3.37, 95% CI 1.04-8.05, p = 0.006). High BAL was also significantly associated with higher odds of shutdown compared to low BAL (OR 2.63, 95% CI 1.15-6.06). Compared to physiologic fibrinolysis, fibrinolysis shutdown was associated with increased mortality (OR 2.87, 95% CI 1.41-5.83) and VFD < 28 (OR 2.54, 95% CI 1.47-4.39). CONCLUSION: In the injured patient, high blood alcohol levels are associated with increased incidence of fibrinolysis shutdown. This finding has implications for postinjury hemostatic resuscitation as these patients may be harmed by anti-fibrinolytics. Further research is needed to assess whether the association with fibrinolysis is modified by the chronicity and type of alcohol consumed and whether anti-fibrinolytic therapy in intoxicated patients produces adverse effects.

Examining the Effect of Hypertonic Saline Administered for Reduction of Intracranial Hypertension on Coagulation.

BACKGROUND: Hypertonic saline (23.4%, HTS) bolus administration is common practice for refractory intracranial hypertension, but its effects on coagulation are unknown. We hypothesize that 23.4% HTS in whole blood results in progressive impairment of coagulation in vitro and in vivo in a murine model of traumatic brain injury (TBI). STUDY DESIGN: For the in vitro study, whole blood was collected from 10 healthy volunteers, and citrated native thrombelastography was performed with normal saline (0.9%, NS) and 23.4% HTS in serial dilutions (2.5%, 5%, and 10%). For the in vivo experiment, we assessed the effects of 23.4% HTS bolus vs NS on serial thrombelastography and tail-bleeding times in a TBI murine model (n = 10 rats with TBI and 10 controls). RESULTS: For the in vitro work, clinically relevant concentrations of HTS (2.5% dilution) shortened time to clot formation and increased clot strength (maximum amplitude) compared with control and NS. With higher HTS dosing (5% and 10% blood dilution), there was progressive prolongation of time to clot formation, decreased angle, and decreased maximum amplitude. In the in vivo study, there was no significant difference in thrombelastography measurements or tail-bleeding times after bolus administration of 23.4% HTS compared with NS at 2.5% blood volume. CONCLUSIONS: At clinically relevant dilutions of HTS, there is a paradoxical shortening of time to clot formation and increase in clot strength in vitro and no significant effects in a murine TBI model. However, with excess dilution, caution should be exercised when using serial HTS boluses in TBI patients at risk for trauma-induced coagulopathy.

Redefining postinjury fibrinolysis phenotypes using two viscoelastic assays.

INTRODUCTION: Fibrinolysis was initially defined using rapid thrombelastography (rTEG). The cutoffs for the pathologic extremes of the fibrinolytic system, hyperfibrinolysis and shutdown, were both defined based on association with mortality. We propose to redefine these phenotypes for both TEG and for rotational thrombelastometry, the other commonly used viscoelastic assay. METHODS: Rotational thrombelastometry, rTEG, and clinical data were prospectively collected on trauma patients admitted to an urban Level I trauma center from 2010 to 2016. Hyperfibrinolysis was defined as the Youden index from EXTEM-clot lysis index 60 minutes after clotting time (CLI60) and rTEG-fibrinolysis 30 minutes after achieving MA (LY30) for predicting massive transfusion (>10 red blood cell units, or death per 6 hours after injury) as a surrogate for severe bleeding. Patients identified as having hyperfibrinolysis were then removed from the data set, and the cutoff for fibrinolysis shutdown was derived as the optimal cutoff for predicting mortality in the remaining patients. RESULTS: Overall, 216 patients (median age, 36 years (interquartile range, 27-49 years), 82% men, 58% blunt injury) were included. Of these, 16% required massive transfusion, and 12.5% died. Rapid thrombelastography phenotypes were redefined as hyperfibrinolysis: rTEG-LY30 greater than7.7%, physiologic rTEG-LY30 0.6% to7.6%, and shutdown rTEG-LY30 less than 0.6%. EXTEM-CLI60 fibrinolysis phenotypes were hyperfibrinolysis CLI60 less than 82%, physiologic (CLI60, 82-97.9%), and shutdown (CLI60 > 98%). Weighted kappa statistics revealed moderate agreement between rotational thrombelastometry- and rTEG-defined fibrinolysis (k = 0.51; 95% confidence interval, 0.39-0.63), with disagreement mostly in the shutdown and physiologic categories. CONCLUSION: We confirmed the U-shaped distribution of death related to fibrinolysis system abnormalities. Both rTEG LY30 and EXTEM CLI60 can identify the spectrum of fibrinolytic phenotypes, have moderate agreement, and can be used to guide hemostatic resuscitation. LEVEL OF EVIDENCE: Diagnostic study, level III.

Variability in international normalized ratio and activated partial thromboplastin time after injury are not explained by coagulation factor deficits.

BACKGROUND: Conventional coagulation assays (CCAs), prothrombin time (PT)/international normalized ratio (INR) and activated partial thromboplastin time (aPTT), detect clotting factor (CF) deficiencies in hematologic disorders. However, there is controversy about how these CCAs should be used to diagnose, treat, and monitor trauma-induced coagulopathy. Study objectives were to determine whether CCA abnormalities are reflective of deficiencies of coagulation factor activity in the setting of severe injury. METHODS: Patients without previous CF deficiency within a prospective database at an ACS-verified Level I trauma center had CF activity levels, PT/INR, aPTT, and fibrinogen levels measured upon emergency department arrival from 2014 to 2017. Linear regression assessed how CF activity explained the aPTT and PT/INR variation. Prolonged CCA values were set as INR greater than 1.3 and aPTT greater than 34 seconds. CF deficiency was defined as less than 30% activity, except for fibrinogen, defined as less than 150 mg/dL. RESULTS: Sixty patients with a mean age of 35.8 (SD, 13.6) years and median New Injury Severity Score of 32 (interquartile range, 12-43) were included; 53.3% sustained blunt injuries, 23.3% required massive transfusion, and mortality was 11.67%. Overall, 44.6% of the PT/INR variance and 49.5% of the aPTT variance remained unexplained by CF activity. Deficiencies of CFs were: common pathway, 25%; extrinsic pathway, 1.7%; and intrinsic pathway, 6.7%. The positive predictive value for CF deficiencies were: (1) PT/INR greater than 1.3:4.4% for extrinsic pathway, 56.5% for the common pathway; (2) aPTT greater than 34 seconds:16.7% for the intrinsic pathway, 73.7% for the common pathway. CONCLUSION: Almost half of the variances of PT/INR and aPTT were unexplained by CF activity. Prolonged PT/INR and aPTT were poor predictors of deficiencies in the intrinsic or extrinsic pathways; however, they were indicators of common pathway deficiencies. LEVEL OF EVIDENCE: Prognostic, level III.

Discrepancies between conventional and viscoelastic assays in identifying trauma-induced coagulopathy.

BACKGROUND: Trauma-induced coagulopathy can present as abnormalities in a conventional or viscoelastic coagulation assay or both. We hypothesized that patients with discordant coagulopathies reflect different clinical phenotypes. METHODS: Blood samples were collected prospectively from critically injured patients upon arrival at two urban Level I trauma centers. International normalized ratio (INR), partial thromboplastin time (PTT), thromboelastography (TEG), and coagulation factors were assayed. RESULTS: 278 patients (median ISS 17, mortality 26%) were coagulopathic: 20% with isolated abnormal INR and/or PTT (CONVENTIONAL), 49% with isolated abnormal TEG (VISCOELASTIC), and 31% with abnormal INR/PTT and TEG (BOTH). Compared with VISCOELASTIC, CONVENTIONAL and BOTH had higher ISS, lower GCS, larger base deficit, and decreased factor activities (all p < 0.017). They received more blood products and had more ICU/ventilation days (all p < 0.017). Mortality was higher in CONVENTIONAL (40%) and BOTH (49%) than VISCOELASTIC (6%, p < 0.017). CONCLUSIONS: Although TEG-guided resuscitation improves survival after injury, INR and PTT identify coagulopathic patients with highest mortality regardless of TEG and likely represent distinct mechanisms independent of biochemical clot strength.

Selective organ ischaemia/reperfusion identifies liver as the key driver of the post-injury plasma metabolome derangements.

BACKGROUND: Understanding the molecular mechanisms in perturbation of the metabolome following ischaemia and reperfusion is critical in developing novel therapeutic strategies to prevent the sequelae of post-injury shock. While the metabolic substrates fueling these alterations have been defined, the relative contribution of specific organs to the systemic metabolic reprogramming secondary to ischaemic or haemorrhagic hypoxia remains unclear. MATERIALS AND METHODS: A porcine model of selected organ ischaemia was employed to investigate the relative contribution of liver, kidney, spleen and small bowel ischaemia/reperfusion to the plasma metabolic phenotype, as gleaned through ultra-high performance liquid chromatography-mass spectrometry-based metabolomics. RESULTS: Liver ischaemia/reperfusion promotes glycaemia, with increases in circulating carboxylic acid anions and purine oxidation metabolites, suggesting that this organ is the dominant contributor to the accumulation of these metabolites in response to ischaemic hypoxia. Succinate, in particular, accumulates selectively in response to the hepatic ischemia, with levels 6.5 times spleen, 8.2 times small bowel, and 6 times renal levels. Similar trends, but lower fold-change increase in comparison to baseline values, were observed upon ischaemia/reperfusion of kidney, spleen and small bowel. DISCUSSION: These observations suggest that the liver may play a critical role in mediating the accumulation of the same metabolites in response to haemorrhagic hypoxia, especially with respect to succinate, a metabolite that has been increasingly implicated in the coagulopathy and pro-inflammatory sequelae of ischaemic and haemorrhagic shock.

Thrombin Provokes Degranulation of Platelet α-Granules Leading to the Release of Active Plasminogen Activator Inhibitor-1 (PAI-1).

BACKGROUND: The balance of fibrinolytic mediators is crucial to the survival of the critically ill patient, with tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) playing significant roles. While elevated levels of PAI-1 are associated with increased morbidity and mortality, the source of this PAI-1 remains elusive. Platelets contain 90% of circulating plasma PAI-1, however, their ability to release active PAI-1 is controversial. We hypothesize platelets contain active PAI-1 in α-granules capable of immediate degranulation when exposed to high concentrations of thrombin. METHODS: In vitro apheresis platelets were stimulated with thrombin (1 IU/mL, 5 IU/mL) followed by the collection of supernatant (5-120 min). Supernatant and lysate PAI-1 was measured by ELISA. The experiment was repeated in the presence of t-PA followed by measurement of t-PA:PAI-1 complex measurement by ELISA. Finally, healthy whole blood underwent dilution with control and thrombin-treated platelet lysate followed by thrombelastography (TEG) in a t-PA-stimulated TEG. RESULTS: Thrombin provoked immediate near-complete degranulation of PAI-1 from α-granules (median 5m 5 IU/mL thrombin 125.1 ng/mL, 1 IU/mL thrombin 114.9 ng/mL, control 9.9 ng/mL). The released PAI-1 rapidly complexed with t-PA, with a 4-fold increase in complex formation in the thrombin-treated supernatant. Conversely, PAI-1 in the control lysate demonstrated a 6-fold increase in complex formation compared with thrombin lysate. Last, control platelet lysate inhibited t-PA-induced fibrinolysis by TEG (median LY30 control 15m 7.9%), while thrombin-treated platelet lysates, after PAI-1 degranulation, were unable to affect the fibrinolysis profile (median LY30 5 IU/mL 28.5%, 1 IU/mL 12.4%). CONCLUSION: Thrombin provokes rapid α-degranulation of active PAI-1, capable of complexing with t-PA and neutralizing t-PA-induced fibrinolysis by TEG.

Empiric transfusion strategies during life-threatening hemorrhage.

BACKGROUND: Resuscitation guided by thrombelastography improves survival after injury. If bleeding is rapid, however, or if no thrombelastography data are available, the optimal strategy remains controversial. Our current practice gives fresh frozen plasma and red blood cells (1:2) empirically in patients with life-threatening hemorrhage, with subsequent administration based on rapid thrombelastography. We identified patients at risk of massive transfusion at 1 hour, examined their initial rapid thrombelastography, and used this value to provide empiric recommendations about transfusions. METHODS: Massive transfusion was defined as >4 units of red blood cells in the first hour. Patients managed by a trauma activation (2014-2017) had an admission rapid thrombelastography analyzed to determine what proportion met thresholds for administration of cryoprecipitate or platelets. RESULTS: Overall, 35 patients received >4 units of red blood cells in the first hour. Based on the admission rapid thrombelastography, 37% met criteria for both platelets and cryoprecipitate, 35% for either platelets or cryoprecipitate and 29% for neither. Kaplan-Meier analysis showed a significant delay in the administration of cryoprecipitate and platelets compared to fresh frozen plasma. CONCLUSION: Patients who require >4 units of red blood cells within the first hour should receive cryoprecipitate and platelets if thrombelastography results are not available. Point-of-care devices are needed for optimal care of trauma-induced-coagulopathy, but these data offer guidance in their absence.

Citrated kaolin thrombelastography (TEG) thresholds for goal-directed therapy in injured patients receiving massive transfusion.

INTRODUCTION: Goal-directed hemostatic resuscitation based on thrombelastography (TEG) has a survival benefit compared with conventional coagulation assays such as international normalized ratio, activated partial thromboplastin time, fibrinogen level, and platelet count. While TEG-based transfusion thresholds for patients at risk for massive transfusion (MT) have been defined using rapid TEG, cutoffs have not been defined for TEG using other activators such as kaolin. The purpose of this study was to develop thresholds for blood product transfusion using citrated kaolin TEG (CK-TEG) in patients at risk for MT. METHODS: CK-TEG was assessed in trauma activation patients at two Level 1 trauma centers admitted between 2010 and 2017. Receiver operating characteristic (ROC) curve analyses were performed to test the predictive performance of CK-TEG measurements in patients requiring MT, defined as >10 units of red blood cells or death within the first 6 hours. The Youden Index defined optimal thresholds for CK-TEG-based resuscitation. RESULTS: Of the 825 trauma activations, 671 (81.3%) were men, 419 (50.8%) suffered a blunt injury, and 62 (7.5%) received a MT. Patients who had a MT were more severely injured, had signs of more pronounced shock, and more abnormal coagulation assays. CK-TEG R-time was longer (4.9 vs. 4.4 min, p = 0.0084), angle was lower (66.2 vs. 70.3 degrees, p < 0.0001), maximum amplitude was lower in MT (57 vs. 65.5 mm, p < 0.0001), and LY30 was greater (1.8% vs. 1.2%, p = 0.0012) in patients with MT compared with non-MT. To predict MT, R-time yielded an area under the ROC curve (AUROC) = 0.6002 and a cut point of >4.45 min. Angle had an AUROC = 0.6931 and a cut point of <67 degrees. CMA had an AUROC = 0.7425, and a cut point of <60 mm. LY30 had an AUROC = 0.623 with a cut point of >4.55%. CONCLUSION: We have identified CK-TEG thresholds that can guide MT in trauma. We propose plasma transfusion for R-time >4.45 min, fibrinogen products for an angle <67 degrees, platelet transfusion for MA <60 mm, and antifibrinolytics for LY30 >4.55%. LEVEL OF EVIDENCE: Therapeutic study, level V.

The Metabolopathy of Tissue Injury, Hemorrhagic Shock, and Resuscitation in a Rat Model.

INTRODUCTION: The metabolic consequences of trauma induce significant clinical pathology. In this study, we evaluate the independent, metabolic contributions of tissue injury (TI) and combined tissue injury and hemorrhagic shock (TI/HS) using mass spectrometry (MS) metabolomics in a controlled animal model of critical injury. METHODS: Sprague-Dawley rats (n = 14) underwent TI alone or TI/HS, followed by resuscitation with normal saline and shed blood. Plasma was collected (baseline, post-laparotomy, post-HS, post-resuscitation) for ultra-high pressure liquid chromatography MS-metabolomics. Repeated-measures ANOVA with Tukey multiple column comparison test compared the fold change of metabolite concentration among the animal groups at corresponding time points. RESULTS: Four hundred forty metabolites were identified. TI alone did not change the metabolite levels versus baseline. TI/HS induced changes in metabolites from glycolysis, the tricarboxylic acid cycle, the pentose phosphate, fatty acid and glutathione homeostasis pathways, sulfur metabolism, and urea cycle versus TI alone. Following resuscitation many metabolites normalized to TI alone levels, including lactate, most tri-carboxylic acid metabolites, most urea cycle metabolites, glutathione disulfide, and some metabolites from both the pentose phosphate pathway and sulfur metabolism. CONCLUSIONS: Significant changes occur immediately following TI/HS versus TI alone. These metabolic changes are not explained by dilution as a number of metabolites remained unchanged or even increased following resuscitation. The differential metabolic changes resulting from TI alone and TI/HS provide foundation for future investigations severe injury in humans, where TI and HS are often concurrent. This investigation provides a foundation to evaluate metabolic-related outcomes and design-targeted resuscitation strategies.

Platelet adenosine diphosphate receptor inhibition provides no advantage in predicting need for platelet transfusion or massive transfusion.

BACKGROUND: Thrombelastography platelet mapping is a useful assay to assess antiplatelet therapy. Inhibited response to the adenosine diphosphate receptor on platelets occurs early after injury, but recent work suggests this alteration occurs even with minor trauma. However, the utility of thrombelastography platelet mapping, specifically the percent of adenosine diphosphate receptor inhibition, in predicting outcomes and guiding platelet transfusion in trauma-induced coagulopathy remains unknown We assessed the role of percent of adenosine diphosphate-inhibition in predicting survival, requirement for massive transfusion or platelet transfusion in patients at risk for trauma-induced coagulopathy. METHODS: Thrombelastography platelet mapping was assessed in 303 trauma activation patients from 2014-2016 and in 89 healthy volunteers. Percent of adenosine diphosphate-inhibition is presented as median and interquartile range. We compared the area under the receiver operating characteristic curve of percent of adenosine diphosphate-inhibition, platelet count, and rapid thrombelastography maximum amplitude for in-hospital mortality, massive transfusion (>10 red blood cells or death/6 hours), and platelet transfusion (>0 platelet units or death/6 hour). RESULTS: Overall, 35 (11.5%) patient died, 27 (8.9%) required massive transfusion and 46, platelet transfusions (15.2%). Median percent of adenosine diphosphate-inhibition was 42.5% (interquartile range: 22.4-69.1%), compared with 4.3 % (interquartile range: 0-13.5%) in healthy volunteers (P < .0001). Patients that died, had a massive transfusion, or platelet transfusion had higher percent of adenosine diphosphate-inhibition than those that did not (P < .05 for all). However, percent of adenosine diphosphate-inhibition did not add significantly to the predictive performance of maximum amplitude or platelet count for any of the 3 outcomes, after adjustment for confounders. Subgroup analyses by severe traumatic brain injury, severe injury and requirement of red blood cells showed similar results. CONCLUSION: Adenosine diphosphate receptor inhibition did not add predictive value to predicting mortality, massive transfusion, or platelet transfusion. Thus, the role of thrombelastography platelet mapping as a solitary tool to guide platelet transfusions in trauma requires continued refinement.

The hypercoagulability paradox of chronic kidney disease: The role of fibrinogen.

BACKGROUND: Chronic kidney disease (CKD) patients have increased rates of bleeding as well as thrombosis. Fibrinogen and platelets combine to generate a mature clot, but in CKD platelets are dysfunctional. Therefore, we hypothesize that CKD patients have increased clot strength due to elevated fibrinogen levels. METHODS: Retrospective review of CKD patients (n = 84) who had rTEG and fibrinogen levels measured. They were compared to healthy controls (n = 134). RESULTS: CKD patients had statistically significant increases in ACT, angle, MA and decreases in LY30 compared to controls. Fibrinogen levels were increased in CKD patients compared to reference range. Fibrinogen levels had a positive correlation with MA (rho = 0.709, p < 0.0001) in CKD patients. CONCLUSIONS: Patients with CKD manifest a coagulopathy consisting of delayed clot formation, but increased final clot strength and decreased clot breakdown. Furthermore, the elevated clot strength is mediated by increased fibrinogen levels in CKD patients.