Fibrinolytic shutdown diagnosed with rotational thromboelastometry represents a moderate form of coagulopathy associated with transfusion requirement and mortality: A retrospective analysis

Dosing of tranexamic acid in trauma

PURPOSE OF REVIEW

Tranexamic acid is routinely used as part of the management of traumatic bleeding. The dose recommendation in trauma was extrapolated from other clinical settings and the results of pragmatic randomized trials rather than pharmaco-kinetic and -dynamic evaluations. The review addresses current evidence on dosing of tranexamic acid in traumatized patients with a focus on efficacy, safety and risk-benefit profile.

RECENT FINDINGS

A majority, but not all, of existing randomized clinical trials reports a reduction in mortality and/or blood loss with tranexamic acid administration. Increasing dose above the general recommendation (1 g bolus + 1 g infusion/8 h intravenously) has not been shown to further increase efficacy and could potentially increase side effects.

SUMMARY

The benefit of tranexamic acid as adjuvant therapy in the management of bleeding trauma patients on mortality and transfusion requirements is clear and well documented, being most effective if given early and to patients with clinical signs of hemorrhagic shock. Recent reports suggest that in some patients presenting with a shutdown of their fibrinolytic pathway the administration of tranexamic acid could be associated with an increased risk of thromboembolic events and poor outcomes. A more personalized approach based on bedside assessment of fibrinolytic activation and pharmacokinetic-based dose regimen should be developed moving forward.

A new global fibrinolysis capacity assay for the sensitive detection of hyperfibrinolysis and hypofibrinogenemia in trauma patients

BACKGROUND

Conventional clotting tests are not expeditious enough to allow timely targeted interventions in trauma, and current point-of-care analyzers, such as rotational thromboelastometry (ROTEM), have limited sensitivity for hyperfibrinolysis and hypofibrinogenemia.

OBJECTIVES

To evaluate the performance of a recently developed global fibrinolysis capacity (GFC) assay in identifying fibrinolysis and hypofibrinogenemia in trauma patients.

METHODS

Exploratory analysis of a prospective cohort of adult trauma patients admitted to a single UK major trauma center and of commercially available healthy donor samples was performed. Lysis time (LT) was measured in plasma according to the GFC manufacturer's protocol, and a novel fibrinogen-related parameter (percentage reduction in GFC optical density from baseline at 1 minute) was derived from the GFC curve. Hyperfibrinolysis was defined as a tissue factor-activated ROTEM maximum lysis of >15% or LT of ≤30 minutes.

RESULTS

Compared to healthy donors (n = 19), non-tranexamic acid-treated trauma patients (n = 82) showed shortened LT, indicative of hyperfibrinolysis (29 minutes [16-35] vs 43 minutes [40-47]; p < .001). Of the 63 patients without overt ROTEM-hyperfibrinolysis, 31 (49%) had LT of ≤30 minutes, with 26% (8 of 31) of them requiring major transfusions. LT showed increased accuracy compared to maximum lysis in predicting 28-day mortality (area under the receiver operating characteristic curve, 0.96 [0.92-1.00] vs 0.65 [0.49-0.81]; p = .001). Percentage reduction in GFC optical density from baseline at 1 minute showed comparable specificity (76% vs 79%) to ROTEM clot amplitude at 5 minutes from tissue factor-activated ROTEM with cytochalasin D in detecting hypofibrinogenemia but correctly reclassified >50% of the patients with false negative results, leading to higher sensitivity (90% vs 77%).

CONCLUSION

Severe trauma patients are characterized by a hyperfibrinolytic profile upon admission to the emergency department. The GFC assay is more sensitive than ROTEM in capturing hyperfibrinolysis and hypofibrinogenemia but requires further development and automation.

Die perioperative Gabe von Tranexamsäure

The application of tranexamic acid (TXA) during endoprosthetic surgical procedures has significantly increased in recent years. Due its ability to reduce perioperative blood loss and avert the need for blood transfusions as well as wound drainage, TXA is becoming part of a 'standard practice'. However, TXA is currently not approved for the application during endoprosthetic procedures and therefore, a benefit-risk analysis should always be conducted. Prophylactic administration of TXA without prior patient consent is only justified if fibrinolytic bleeding is expected and there are no contraindications or relevant risk factors for thromboembolic complications. Respectively, no patient consent is required when a therapeutic dose of TXA is administered in the context of fibrinolytic bleeding. The following guidelines provide updated recommendations based on the current state of knowledge on TXA optimal timing, routes of administration and dosing regimen.

State-by-state estimates of avoidable trauma mortality with early and liberal versus delayed or restricted administration of tranexamic acid

OBJECTIVE

Early administration of tranexamic acid (TXA) has been shown to save lives in trauma patients, and some U.S. emergency medical systems (EMS) have begun providing this therapy prehospital. Treatment protocols vary from state to state: Some offer TXA broadly to major trauma patients, others reserve it for patients meeting vital sign criteria, and still others defer TXA entirely pending a hospital evaluation. The purpose of this study is to compare the avoidable mortality achievable under each of these strategies, and to report on the various approaches used by EMS.

METHODS

We used the National Center for Health Statistics Underlying Cause of Death data to identify a TXA-naïve population of trauma patients who died from 2007 to 2012 due to hemorrhage. We estimated the proportion of deaths where the patient was hypotensive or tachycardic using the National Trauma Data Bank. We used avoidable mortality risk ratios from the landmark CRASH 2 study to calculate lives saved had TXA been given within one hour of injury based on a clinician's gestalt the patient was at risk for significant hemorrhage; had it been reserved only for hypotensive or tachycardic patients; or had it been given between hours one to three of injury, considered here as a surrogate for deferring the question to the receiving hospital.

RESULTS

Had TXA been given within 1 hour of injury, an average of 3409 deaths per year could have been averted nationally. Had TXA been given between one and three hours after injury, 2236 deaths per year could have been averted. Had TXA only been given to either tachycardic or hypotensive trauma patients, 1371 deaths per year could have been averted. Had TXA only been given to hypotensive trauma patients, 616 deaths per year could have been averted. Similar trends are seen at the individual state level. A review of EMS practices found 15 statewide protocols that allow EMS providers to administer TXA for trauma.

CONCLUSION

Providing early TXA to persons at risk of significant hemorrhage has the potential to prevent many deaths from trauma, yet most states do not offer it in statewide prehospital treatment protocols.

Temporal Transitions in Fibrinolysis after Trauma: Adverse Outcome Is Principally Related to Late Hypofibrinolysis

BACKGROUND

The relationship between late clinical outcomes after injury and early dynamic changes between fibrinolytic states is not fully understood. The authors hypothesized that temporal transitions in fibrinolysis states using rotational thromboelastometry (ROTEM) would aid stratification of adverse late clinical outcomes and improve understanding of how tranexamic acid modulates the fibrinolytic response and impacts mortality.

METHODS

The authors conducted a secondary analysis of previously collected data from trauma patients enrolled into an ongoing prospective cohort study (International Standard Randomised Controlled Trial Number [ISRCTN] 12962642) at a major trauma center in the United Kingdom. ROTEM was performed on admission and at 24 h with patients retrospectively grouped into three fibrinolysis categories: tissue factor-activated ROTEM maximum lysis of less than 5% (low); tissue factor-activated ROTEM maximum lysis of 5 to 15% (normal); or tissue factor-activated ROTEM maximum lysis of more than 15% (high). Primary outcomes were multiorgan dysfunction syndrome and 28-day mortality.

RESULTS

Seven-hundred thirty-one patients were included: 299 (41%) were treated with tranexamic acid and 432 (59%) were untreated. Two different cohorts with low-maximum lysis at 24 h were identified: (1) severe brain injury and (2) admission shock and hemorrhage. Multiple organ dysfunction syndrome was greatest in those with low-maximum lysis on admission and at 24 h, and late mortality was four times higher than in patients who remained normal during the first 24 h (7 of 42 [17%] vs. 9 of 223 [4%]; P = 0.029). Patients that transitioned to or remained in low-maximum lysis had increased odds of organ dysfunction (5.43 [95% CI, 1.43 to 20.61] and 4.85 [95% CI, 1.83 to 12.83], respectively). Tranexamic acid abolished ROTEM hyperfibrinolysis (high) on admission, increased the frequency of persistent low-maximum lysis (67 of 195 [34%]) vs. 8 of 79 [10%]; P = 0.002), and was associated with reduced early mortality (28 of 195 [14%] vs. 23 of 79 [29%]; P = 0.015). No increase in late deaths, regardless of fibrinolysis transition patterns, was observed.

CONCLUSIONS

Adverse late outcomes are more closely related to 24-h maximum lysis, irrespective of admission levels. Tranexamic acid alters early fibrinolysis transition patterns, but late mortality in patients with low-maximum lysis at 24 h is not increased.

EDITOR’S PERSPECTIVE

Pathophysiology of Trauma-Induced Coagulopathy

There is no standard definition for trauma-induced coagulopathy (TIC). However, it could be defined as an abnormal hemostatic response secondary to trauma. The terms "early TIC" and "late TIC" have been recently suggested. "Early TIC" would refer to the inability to achieve effective hemostasis exacerbating an uncontrolled bleeding in a shocked patient with ischemia-reperfusion damage (bleeding phenotype) and takes place usually early after injury, whereas "late TIC" would represent a hypercoagulable state after surviving a severe tissue injury, that would contribute to thromboembolic events and multiorgan failure (MOF), (thrombotic phenotype), occurring typically hours after the trauma insult though it could be delayed for days. In addition, severe tissue injury when there is no associated shock could be followed by an early hypercoagulable state, representing an evolutionary maladaptive response of a physiologic mechanism created to increase clot formation and prevent bleeding. Therefore, TIC is not a uniform phenotype, ranging from bleeding to pro-thrombotic profiles. This current concept of TIC is mainly based on the recognition of TIC as a unique clotting disorder following trauma in which alterations in the endothelial function, fibrinolysis regulation and platelet behavior after major trauma are the main cornerstones.

Effect of Prophylactic Embolization on Patients With Blunt Trauma at High Risk of Splenectomy: A Randomized Clinical Trial

Importance

Splenic arterial embolization (SAE) improves the rate of spleen rescue, yet the advantage of prophylactic SAE (pSAE) compared with surveillance and then embolization only if necessary (SURV) for patients at high risk of spleen rupture remains controversial.

Objective

To determine whether the 1-month spleen salvage rate is better after pSAE or SURV.

Design, Setting, and Participants

In this randomized clinical trial conducted between February 6, 2014, and September 1, 2017, at 16 institutions in France, 133 patients with splenic trauma at high risk of rupture were randomized to undergo pSAE or SURV. All analyses were performed on a per-protocol basis, as well as an intention-to-treat analysis for specific events.

Interventions

Prophylactic SAE, preferably using an arterial approach via the femoral artery, or SURV.

Main Outcomes and Measures

The primary end point was an intact spleen or a spleen with at least 50% vascularized parenchyma detected on an arterial computed tomography scan at 1 month after trauma, assessed by senior radiologists masked to the treatment group. Secondary end points included splenectomy and pseudoaneurysm, secondary SAE after inclusion, complications, length of hospital stay, quality-of-life score, and length of time off work or studies during the 6-month follow-up.

Results

A total of 140 patients were randomized, and 133 (105 men [78.9%]; median age, 30 years [interquartile range, 23-47 years]) were retained in the study. For the primary end point, data from 117 patients (57 who underwent pSAE and 60 who underwent SURV) could be analyzed. The number of patients with at least a 50% viable spleen detected on a computed tomography scan at month 1 was not significantly different between the pSAE and SURV groups (56 of 57 [98.2%] vs 56 of 60 [93.3%]; difference, 4.9%; 95% CI, -2.4% to 12.1%; P = .37). By the day 5 visit, there were significantly fewer splenic pseudoaneurysms among patients in the pSAE group than in the SURV group (1 of 65 [1.5%] vs 8 of 65 [12.3%]; difference, -10.8%; 95% CI, -19.3% to -2.1%; P = .03), significantly fewer secondary embolizations among patients in the pSAE group than in the SURV group (1 of 65 [1.5%] vs 19 of 65 [29.2%]; difference, -27.7%; 95% CI, -41.0% to -15.9%; P < .001), and no difference in the overall complication rate between the pSAE and SURV groups (19 of 65 [29.2%] vs 27 of 65 [41.5%]; difference, -12.3%; 95% CI, -28.3% to 4.4%; P = .14). Between the day 5 and month 1 visits, the overall complication rate was not significantly different between the pSAE and SURV groups (11 of 59 [18.6%] vs 12 of 63 [19.0%]; difference, -0.4%; 95% CI, -14.4% to 13.6%; P = .96). The median length of hospitalization was significantly shorter for patients in the pSAE group than for those in the SURV group (9 days [interquartile range, 6-14 days] vs 13 days [interquartile range, 9-17 days]; P = .002).

Conclusions and Relevance

Among patients with splenic trauma at high risk of rupture, the 1-month spleen salvage rate was not statistically different between patients undergoing pSAE compared with those receiving SURV. In view of the high proportion of patients in the SURV group needing SAE, both strategies appear defendable.

Trial Registration

ClinicalTrials.gov Identifier: NCT02021396.

Is Tranexamic Acid Associated With Mortality or Multiple Organ Failure Following Severe Injury?

BACKGROUND

Tranexamic acid (TXA) administration is recommended in severely injured trauma patients. We examined TXA administration, admission fibrinolysis phenotypes, and clinical outcomes following traumatic injury and hypothesized that TXA was associated with increased multiple organ failure (MOF).

METHODS

Two-year, single-center, retrospective investigation. Inclusion criteria were age ≥ 18 years, Injury Severity Score (ISS) >16, admitted from scene of injury, thromboelastography within 30 min of arrival. Fibrinolysis was evaluated by lysis at 30 min (LY30) and fibrinolysis phenotypes were defined as: Shutdown: LY30 ≤ 0.8%, Physiologic: LY30 0.81-2.9%, Hyperfibrinolysis: LY30 ≥ 3.0%. Primary outcomes were 28-day mortality and MOF. The association of TXA with mortality and MOF was assessed among the entire study population and in each of the fibrinolysis phenotypes.

RESULTS

Four hundred twenty patients: 144/420 Shutdown (34.2%), 96/420 Physiologic (22.9%), and 180/410 Hyperfibrinolysis (42.9%). There was no difference in 28-day mortality by TXA administration among the entire study population (P = 0.52). However, there was a significant increase in MOF in patients who received TXA (11/46, 23.9% vs 16/374, 4.3%; P < 0.001). TXA was associated MOF (OR: 3.2, 95% CI 1.2-8.9), after adjusting for confounding variables. There was no difference in MOF in patients who received TXA in the Physiologic (1/5, 20.0% vs 7/91, 7.7%; P = 0.33) group. There was a significant increase in MOF among patients who received TXA in the Shutdown (3/11, 27.3% vs 5/133, 3.8%; P = 0.001) and Hyperfibrinolysis (7/30, 23.3% vs 5/150, 3.3%; P = 0.001) groups.

CONCLUSIONS

Administration of TXA following traumatic injury was associated with MOF in the fibrinolysis shutdown and hyperfibrinolysis phenotypes and warrants continued evaluation.

"TEG talk": expanding clinical roles for thromboelastography and rotational thromboelastometry

Viscoelastic assays (VEAs) that include thromboelastography and rotational thromboelastometry add value to the investigation of coagulopathies and goal-directed management of bleeding by providing a complete picture of clot formation, strength, and lysis in whole blood that includes the contribution of platelets, fibrinogen, and coagulation factors. Conventional coagulation assays have several limitations, such as their lack of correlation with bleeding and hypercoagulability; their inability to reflect the contribution of platelets, factor XIII, and plasmin during clot formation and lysis; and their slow turnaround times. VEA-guided transfusion algorithms may reduce allogeneic blood exposure during and after cardiac surgery and in the emergency management of trauma-induced coagulopathy and hemorrhage. However, the popularity of VEAs for other indications is driven largely by extrapolation of evidence from cardiac surgery, by the drawbacks of conventional coagulation assays, and by institution-specific preferences. Robust diagnostic studies validating and standardizing diagnostic cutoffs for VEA parameters and randomized trials comparing VEA-guided algorithms with standard care on clinical outcomes are urgently needed. Lack of such studies represents the biggest barrier to defining the role and impact of VEA in clinical care.