The effects of tranexamic acid and prothrombin complex concentrate on the coagulopathy of trauma: an in vitro analysis of the impact of severe acidosis

Intramuscular administration of tranexamic acid in a large swine model of hemorrhage with hyperfibrinolysis

BACKGROUND

Traumatic injury with subsequent hemorrhage is one of the leading causes of mortality among military personnel and civilians alike. Posttraumatic hemorrhage accounts for 40% to 50% of deaths in severe trauma patients occurring secondary to direct vessel injury or the development of trauma-induced coagulopathy (TIC). Hyperfibrinolysis plays a major role in TIC and its presence increases a patient's risk of mortality. Early therapeutic intervention with intravenous (IV) tranexamic acid (TXA) prevents development of hyperfibrinolysis and subsequent TIC leading to decreased mortality. However, obtaining IV access in an austere environment can be challenging. In this study, we evaluated the efficacy of intramuscular (IM) versus IV TXA at preventing hyperfibrinolysis in a hemorrhaged swine.

METHODS

Yorkshire cross swine were randomized on the day of study to receive IM or IV TXA or no treatment. Swine were sedated, intubated, and determined to be hemodynamically stable before experimentation. Controlled hemorrhaged was induced by the removal of 30% total blood volume. After hemorrhage, swine were treated with 1,000 mg of IM or IV TXA. Control animals received no treatment. Thirty minutes post-TXA treatment, fibrinolysis was induced with a 50-mg bolus of tissue plasminogen activator. Blood samples were collected to evaluate blood TXA concentrations, blood gases, blood chemistry, and fibrinolysis.

RESULTS

Blood TXA concentrations were significantly different between administration routes at the early time points but were equivalent by 20 minutes after injection, remaining consistently elevated for up to 3 hours postadministration. Induction of fibrinolysis resulted in 87.18 ± 4.63% lysis in control animals, compared with swine treated with IM TXA, 1.96 ± 2.66% and 1.5 ± 0.42% lysis in the IV TXA group.

CONCLUSION

In the large swine model of hemorrhage with hyperfibrinolysis, IM TXA is bioequivalent and equally efficacious in preventing hyperfibrinolysis as IV TXA administration.

Thromboelastometry assessment of the effects of fibrinogen, activated prothrombin complex concentrate, and tranexamic acid on clot formation and fibrinolysis in a model of trauma-induced coagulopathy

PURPOSE

Coagulation abnormalities are common following major trauma. The aim of this study was to assess the improvement of trauma-induced coagulopathy (TIC) in an in vitro model.

METHODS

TIC was created on blood taken from healthy individuals by inducing hemodilution, acidosis, hypothermia and fibrinolysis. Next, blood samples were subjected to rotational thromboelastometry to assess the effect of hemostasis modulators on blood coagulation and fibrinolysis.

RESULTS

Introducing to blood fibrinogen at 0.75 mg/mL, prothrombin complex concentrate at 0.66 IU/mL or tranexamic acid at 95 µg/mL increased clot strength. Higher effect was observed by combination of fibrinogen with tranexamic acid and prothrombin complex with tranexamic acid, whereas the maximal effect was achieved using all agents together. Fibrinolysis was inhibited by tranexamic acid and stronger by triple combination of the agents. Selective treating the TIC blood with fibrinogen, prothrombin complex or tranexamic acid at two time lower concentrations did not affect clot strength. Combining fibrinogen with prothrombin complex or with tranexamic acid stimulated clot strength but at lower extent compared to higher concentrations. Lysis onset time was prolonged by tranexamic acid. Maximal effect on both clot formation and fibrinolysis was achieved using all three agents together.

CONCLUSIONS

Blood clotting stimulation and fibrinolysis inhibition in the TIC model was enough combining subthreshold concentrations of fibrinogen, prothrombin complex and tranexamic acid. Further experiments are warranted in both in vitro and in vivo conditions with minimally effective concentrations of both pro-coagulant and anti-fibrinolytic drugs assuming that this combinatorial approach may not only improve coagulopathy but also minimize the risk of thrombotic complications.

The use of new procoagulants in blunt and penetrating trauma

PURPOSE OF REVIEW

Uncontrolled bleeding in trauma secondary to a combination of surgical bleeding and trauma-induced complex coagulopathy is a leading cause of death. Prothrombin complex concentrates (PCCs), recombinant activated factor seven (rFVIIa) and recombinant human prothrombin act as procoagulants by increasing thrombin generation and fibrinogen concentrate aids stable clot formation. This review summarizes the current evidence for procoagulant use in the management of bleeding in trauma, and data and evidence gaps for routine clinical use.

RECENT FINDINGS

Retrospective and prospective studies of PCCs (±fibrinogen concentrate) have demonstrated a decreased time to correction of trauma coagulopathy and decreased red cell transfusion with no obvious effect on mortality or thromboembolic outcomes. PCCs in a porcine model of dilutional coagulopathy demonstrated a sustained increase in thrombin generation, unlike recombinant human prothrombin which showed a transient increase and has been studied only in animals. In other retrospective studies, there is a suggestion that lower doses of PCCs may be effective in the setting of acquired coagulopathy.

SUMMARY

There is increasing evidence that early correction of coagulopathy has survival benefits, and the use of procoagulants as first-line therapy has the potential benefit of rapid access and timely treatment. This requires confirmation in prospective studies.

No intravenous access, no problem: Intraosseous administration of tranexamic acid is as effective as intravenous in a porcine hemorrhage model

BACKGROUND

The acute coagulopathy of trauma is often accompanied by hyperfibrinolysis. Tranexamic acid (TXA) can reverse this phenomenon, and, when given early, decreases mortality from bleeding. Establishing intravenous (IV) access can be difficult in trauma and intraosseous (IO) access is often preferred for drug administration. Currently, there are no data on the efficacy of IO administered TXA. Our objectives were to compare serum concentrations of TXA when given IV and IO and to compare the efficacy of IO administered TXA to IV at reversing hyperfibrinolysis.

METHODS

Using a porcine hemorrhage and ischemia-reperfusion model, 18 swine underwent hemorrhagic shock followed by a tissue plasminogen activator infusion to induce hyperfibrinolysis. Animals then received an IV or tibial IO infusion of TXA over 10 minutes. Blood was then analyzed using rotational thromboelastometry to monitor reversal of hyperfibrinolysis. Serum was analyzed for drug concentrations.

RESULTS

After hemorrhage and ischemia-reperfusion, there were no significant differences in mean arterial pressure (48 vs. 49.5), lactate (11.1 vs. 10.8), and pH (7.20 vs. 7.22) between groups. Intraosseous TXA corrected the lysis index at 30 minutes in EX-TEM and IN-TEM, like IV infusion. Peak serum levels of TXA after IV and IO administration show concentrations of 160.9 μg/mL and 132.57 μg/mL respectively (p = 0.053). Peak levels occurred at the completion of infusion. Drug levels were tracked for four hours. At the end of monitoring, plasma concentrations of TXA were equivalent.

CONCLUSION

Intraosseous administration of TXA is as effective as IV in reversing hyperfibrinolysis in a porcine model of hemorrhagic shock. Intraosseous administration was associated with a similar peak levels, pharmacokinetics, and clearance. Intraosseous administration of TXA can be considered in hemorrhagic shock when IV access cannot be established.

Postpartum hemorrhage: Blood product management and massive transfusion

Blood product transfusion capabilities are crucial for appropriate response to postpartum hemorrhage. Novel treatments are continually being sought to improve maternal morbidity and mortality associated with massive hemorrhage.

Plasma coadministration improves resuscitation with tranexamic acid or prothrombin complex in a porcine hemorrhagic shock model

BACKGROUND

Traumatic coagulopathy has now been well characterized and carries high rates of mortality owing to bleeding. A 'factor-based' resuscitation strategy using procoagulant drugs and factor concentrates in lieu of plasma is being used by some, but with little evidentiary support. We sought to evaluate and compare resuscitation strategies using combinations of tranexamic acid (TXA), prothrombin complex concentrate (PCC), and fresh frozen plasma (FFP).

METHODS

Sixty adult swine underwent 35% blood volume hemorrhage combined with a truncal ischemia-reperfusion injury to produce uniform shock and coagulopathy. Animals were randomized to control (n = 12), a single-agent group (TXA, n = 10; PCC, n = 8; or FFP, n = 6) or combination groups (TXA-FFP, n = 10; PCC-FFP, n = 8; TXA-PCC, n = 6). Resuscitation was continued to 6 hours. Key outcomes included hemodynamics, laboratory values, and rotational thromboelastometry. Results were compared between all groups, with additional comparisons between FFP and non-FFP groups.

RESULTS

All 60 animals survived to 6 hours. Shock was seen in all animals, with hypotension (mean arterial pressure, 44 mm Hg), tachycardia (heart rate, 145), acidosis (pH 7.18; lactate, 11), anemia (hematocrit, 17), and coagulopathy (fibrinogen, 107). There were clear differences between groups for mean pH (p = 0.02), international normalized ratio (p < 0.01), clotting time (CT; p < 0.01), lactate (p = 0.01), creatinine (p < 0.01), and fibrinogen (p = 0.02). Fresh frozen plasma groups had significantly improved resuscitation and clotting parameters (Figures), with lower lactate at 6.5 versus 8.4 (p = 0.04), and increased fibrinogen at 126 versus 95 (p < 0.01). Rotational thromboelastometry also demonstrated shortened CT at 60 seconds in the FFP group vs 65 seconds in the non-FFP group (p = 0.04).

CONCLUSION

When used to correct traumatic coagulopathy, combinations of FFP with TXA or PCC were superior in improving acidosis, coagulopathy, and CT than when these agents are given alone or in combination without plasma. Further validation of pure factor-based strategies is needed.

Three- versus four-factor prothrombin complex concentrates for "factor-based" resuscitation in a porcine hemorrhagic shock model

BACKGROUND

Bleeding is a leading cause of preventable death after severe injury. Prothrombin complex concentrates (PCC) treat inborn coagulation disorders and reverse oral anticoagulants, but are proposed for use in "factor-based" resuscitation strategies. Few studies exist for this indication in acidosis, or that compare 3-factor PCC (3PCC) versus 4-factor PCC (4PCC) products. We aimed to assess and compare their safety and efficacy in a porcine model of severe hemorrhagic shock and coagulopathy.

METHODS

Twenty-five adult Yorkshire swine underwent 35% volume hemorrhage, ischemia-reperfusion injury, and protocolized crystalloid resuscitation. Seventeen animals were randomized at 4 hours after model creation to receive a 45-IU/kg dose of either 3PCC or 4PCC. An additional eight animals received autologous plasma transfusion before 4PCC to better characterize response to PCC. Individual factor levels were drawn at 4 hours and 6 hours.

RESULTS

The model created significant acidosis with mean pH of 7.21 and lactate of 9.6 mmol/L. After PCC, 66.7% of 3PCC animals and 25% of 4PCC animals (regardless of plasma administration) developed consumptive coagulopathy. The animals that developed consumptive coagulopathy had manifested the "lethal triad" with lower temperatures (36.3°C vs. 37.8°C), increased acidosis (pH, 7.14 vs. 7.27; base excess, -12.1 vs. -6.5 mEq/L), and worse coagulopathy (prothrombin time, 17.1 vs. 14.6 seconds; fibrinogen, 87.9 vs. 124.1 mg/dL) (all p < 0.05). In the absence of a consumptive coagulopathy, 3PCC and 4PCC improved individual clotting factors with transient improvement of prothrombin time, but there was significant depletion of fibrinogen and platelets with no lasting improvement of coagulopathy.

CONCLUSION

PCC failed to correct coagulopathy and was associated with fibrinogen and platelet depletion. Of greater concern, PCC administration resulted in consumptive coagulopathy in the more severely ill animals. The incidence of consumptive coagulopathy was markedly increased with 3PCC versus 4PCC, and these products should be used with caution in this setting.

Coagulation Management During Liver Transplantation: Use of Fibrinogen Concentrate, Recombinant Activated Factor VII, Prothrombin Complex Concentrate, and Antifibrinolytics

Coagulation management, and transfusion practice in liver transplantation (LT) have been evolving in the recent years due to better understanding of coagulation abnormalities in end-stage liver disease, and clinical management of LT patients. Avoidance of allogeneic blood components is feasible in some patients, but multi-modal coagulation therapies may be necessary in others who develop complex coagulopathy due to hemorrhage, hemodilution, hypothermia, and acid-base disturbances. Transfusions of plasma and cryoprecipitate remain to be the mainstay therapy for procoagulant factor replacement during LT. Clinical efficacy and safety of these products are limited by logistic issues (eg, thawing), and mostly noninfectious complications. Considering potential alternatives to conventional transfusion is thus important to improve hemostatic resuscitation in complex LT cases. The present review is mainly focused on procoagulant properties of plasma and platelet transfusion, and currently available plasma-derived and recombinant factor concentrates, and antifibrinolytic agents in LT patients. The role of viscoelastic coagulation tests to guide specific component therapies will be also discussed.

Experimental Evaluation of Tranexamic Acid-Loaded Porous Starch as a Hemostatic Powder

We evaluated the effectiveness of a novel hemostatic powder called Tranexamic Acid-loaded Porous Starch (TAPS) developed recently on blood clotting activity and hemostasis. The effectiveness of TAPS was evaluated by comparing hemostatic properties with those of Quick-acting Styptic Powder (QSP) and Compound Microporous Polysaccharide Haemostatic powder (CMPHP). The blood clotting activities of human blood were analyzed by thromboela-stogram (TEG) assays in vitro. The hemostatic effectiveness in vivo was evaluated using a rat model with hepatic traumatic hemorrhage. The blood loss and standardized bleeding score, which reflects the degree of bleeding after treatment with styptic powder, were used to evaluate hemostatic efficacy. In vitro, the values of TEG parameters in TAPS group were significantly different, compared with untreated controls or CMPHP group (p < 0.05). In vivo, the application of QSP, CMPHP and TAPS led to significantly decreased post-treatment blood loss than in the control group (p < 0.01). The scores of the groups treated with QSP, CMPHP and TAPS (0, 0.2±0.422, 0.3±0.483, respectively) were significant lower than with gauze control (1.6±0.516) which success hemostatic was achieved at 5 minutes (p < 0.01). Hemostasis was achieved successfully within approximately 4 minutes after the application of TAPS. TAPS could help blood to form an artificial scab on a wound and to seal injuries for hemostasis to reduce blood loss in rats with hepatic trauma and hemorrhage. It was safe to use with no impact on blood clotting function or other apparent side effects.

Combined effect of therapeutic strategies for bleeding injury on early survival, transfusion needs and correction of coagulopathy

BACKGROUND

The combined effects of balanced transfusion ratios and use of procoagulant and antifibrinolytic therapies on trauma-induced exsanguination are not known. The aim of this study was to investigate the combined effect of transfusion ratios, tranexamic acid and products containing fibrinogen on the outcome of injured patients with bleeding.

METHODS

A prospective multicentre observational study was performed in six level 1 trauma centres. Injured patients who received at least 4 units of red blood cells (RBCs) were analysed and divided into groups receiving a low (less than 1 : 1) or high (1 or more : 1) ratio of plasma or platelets to RBCs, and in receipt or not of tranexamic acid or fibrinogen products (fibrinogen concentrates or cryoprecipitate). Logistic regression models were used to assess the effect of transfusion strategies on the outcomes 'alive and free from massive transfusion' (at least 10 units of RBCs in 24 h) and early 'normalization of coagulopathy' (defined as an international normalized ratio of 1·2 or less).

RESULTS

A total of 385 injured patients with ongoing bleeding were included in the study. Strategies that were independently associated with an increased number of patients alive and without massive transfusion were a high platelet to RBC ratio (odds ratio (OR) 2·67, 95 per cent c.i. 1·24 to 5·77; P = 0·012), a high plasma to RBC ratio (OR 2·07, 1·03 to 4·13; P = 0·040) and treatment with tranexamic acid (OR 2·71, 1·29 to 5·71; P = 0·009). No strategies were associated with correction of coagulopathy.

CONCLUSION

A high platelet or plasma to RBC ratio, and use of tranexamic acid were associated with a decreased need for massive transfusion and increased survival in injured patients with bleeding. Early normalization of coagulopathy was not seen for any transfusion ratio, or for use of tranexamic acid or fibrinogen products.

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting

Prothrombin complex concentrates (PCCs) contain vitamin K-dependent clotting factors (II, VII, IX, and X) and are marketed as 3 or 4 factor-PCC formulations depending on the concentrations of factor VII. PCCs rapidly restore deficient coagulation factor concentrations to achieve hemostasis, but like with all procoagulants, the effect is balanced against thromboembolic risk. The latter is dependent on both the dose of PCCs and the individual patient prothrombotic predisposition. PCCs are approved by the US Food and Drug Administration for the reversal of vitamin K antagonists in the setting of coagulopathy or bleeding and, therefore, can be administered when urgent surgery is required in patients taking warfarin. However, there is growing experience with the off-label use of PCCs to treat patients with surgical coagulopathic bleeding. Despite their increasing use, there are limited prospective data related to the safety, efficacy, and dosing of PCCs for this indication. PCC administration in the perioperative setting may be tailored to the individual patient based on the laboratory and clinical variables, including point-of-care coagulation testing, to balance hemostatic benefits while minimizing the prothrombotic risk. Importantly, in patients with perioperative bleeding, other considerations should include treating additional sources of coagulopathy such as hypofibrinogenemia, thrombocytopenia, and platelet disorders or surgical sources of bleeding. Thromboembolic risk from excessive PCC dosing may be present well into the postoperative period after hemostasis is achieved owing to the relatively long half-life of prothrombin (factor II, 60-72 hours). The integration of PCCs into comprehensive perioperative coagulation treatment algorithms for refractory bleeding is increasingly reported, but further studies are needed to better evaluate the safe and effective administration of these factor concentrates.

Tactical damage control resuscitation in austere military environments

BACKGROUND

Despite the early uses of tourniquets and haemostatic dressings, blood loss still accounts for the vast majority of preventable deaths on the battlefield. Over the last few years, progress has been made in the management of such injuries, especially with the use of damage control resuscitation concepts. The early application of these procedures, on the field, may constitute the best opportunity to improve survival from combat injury during remote operations.

DATA SOURCES

Currently available literature relating to trauma-induced coagulopathy treatment and far-forward transfusion was identified by searches of electronic databases. The level of evidence and methodology of the research were reviewed for each article. The appropriateness for field utilisation of each medication was then discussed to take into account the characteristics of remote military operations.

CONCLUSIONS

In tactical situations, in association with haemostatic procedures (tourniquet, suture, etc), tranexamic acid should be the first medication used according to the current guidelines. The use of fibrinogen concentrate should also be considered for patients in haemorrhagic shock, especially if point-of-care (POC) testing of haemostasis or shock severity is available. If POC evaluation is not available, it seems reasonable to still administer this treatment after clinical assessment, particularly if the evacuation is delayed. In this situation, lyophilised plasma may also be given as a resuscitation fluid while respecting permissive hypotension. Whole blood transfusion in the field deserves special attention. In addition to the aforementioned treatments, if the field care is prolonged, whole blood transfusion must be considered if it does not delay the evacuation.

Tranexamic Acid Use in United States Trauma Centers: A National Survey

Tranexamic acid (TXA) is an antifibrinolytic agent that is listed as an essential medication by the World Health Organization for traumatic hemorrhage. We determined United States–based surgeons’ familiarity with TXA and their use of TXA. An online survey was sent to the 1291 attending surgeon members of a national trauma organization. The survey was organized into three general parts: respondent demographics, perceptions of TXA, and experience with TXA. The survey was completed by 35 per cent of members. TXA was available at 89.1 per cent of centers. Experience with TXA was variable: 38.0 per cent use regularly, 24.9 per cent use it 1 to 2 times per year, 12.3 per cent use it rarely, and 24.7 per cent had never used it. Among surgeons who had used TXA, 77.1 per cent noted that TXA had reduced bleeding, but 22.9 per cent indicated that it had not. Reasons for not routinely using TXA included uncertain clinical benefit (47.7%) and unfamiliarity (31.5%). Finally, 90.5 per cent of respondents indicated that are looking toward national organizations to develop practice guidelines. TXA is widely available in civilian United States trauma centers. Although a majority of surveyed surgeons had used TXA, only 38 per cent use TXA regularly for significant traumatic hemorrhage; principal reasons for this are uncertainty regarding clinical benefit and unfamiliarity with the drug. National guidelines are sought.

Factor concentrates in trauma

PURPOSE OF REVIEW

Recent advances in the understanding of transfusion practices during hemorrhagic shock in trauma have led to early administration of thawed plasma in increased ratios to packed red blood cells and have improved survival in the most severely injured patients. As an appreciation for the sequelae of massive transfusion continues to mature, it is becoming apparent that a more targeted approach to coagulation deficiencies may offer an advantage.

RECENT FINDINGS

Factor concentrate therapy offers the advantage of smaller volumes of resuscitative fluids directed at specific phases of coagulation identified by alternative laboratory assays (e.g., viscoelastic testing). Case reports, animal studies, and retrospective reviews offer encouraging data on the ability of factor concentrates to reverse coagulopathy and reduce blood product usage.

SUMMARY

The use of factor concentrates to target specific phases of coagulation may offer benefit over blood product ratio-driven transfusion. The outcome benefit of factor concentrates, however, has not yet been demonstrated in well powered prospective trials.

Prothrombin Complex Concentrates in Trauma and Perioperative Bleeding

There is increasing interest in prothrombin complex concentrates as therapy for perioperative and trauma-related bleeding. A suitable point-of-care test is needed to guide such therapy, and randomized controlled trials are needed for robust, evidence-based recommendations.

Clotting factor XIII and desmopressin improve hemostasis in uncontrolled bleeding

PURPOSE

To investigate hemostatic effects of supplementary factor XIII and desmopressin (DDAVP) in resuscitation of uncontrolled bleeding.

METHODS

Fifty-four rabbits were randomized in nine groups: G1: Sham; G2: FXIII and normotensive resuscitation (NBP); G3: FXIII and permissive hypotension (PH) (MAP 60% baseline); G4: FXIII/DDAVP/NBP; G5: FXIII/DDAVP/PH; G6: NBP only; G7: FXIII no hemorrhage; G8: FXIII/DDAVP no hemorrhage; G9: PH only. Thromboelastometry and intra-abdominal blood loss were assessed. Scanning electron microscopy (EM) of the clots was performed.

RESULTS

Compared to Sham, only G8 (FXIII/DDAVP w/o hemorrhage) showed clotting time (CT) significantly lower (p<0.05). NBP alone (G6) resulted in significantly prolonged CT compared to G2, G3 and G5 (p<0.05). Similarly, median alpha angle was significantly larger in G3,4,5, and 9 compared to G6 (p<0.05). Area under the curve was significantly greater in G5 than G2. Intra-abdominal blood loss was lower in G5 and G9 compared to G2 and G6. FXIII/DDAVP and PH resulted in more robust fibrin mesh by EM.

CONCLUSIONS

Normotensive resuscitation provokes more bleeding and worsens coagulation compared to pH, that is partially reversed by factor XIII and desmopressin. FXIII and DDAVP can synergistically improve coagulation. Permissive hypotension reduces bleeding regardless of those agents.