Prothrombin complex concentrate reduces blood loss and enhances thrombin generation in a pig model with blunt liver injury under severe hypothermia

Blast polytrauma with hemodynamic shock, hypothermia, hypoventilation and systemic inflammatory response: description of a new porcine model

PURPOSE

In the past decade blast injuries have become more prevalent. Blast trauma may cause extensive injuries requiring improved early resuscitation and prevention of haemorrhage. Randomized prospective trials are logistically and ethically challenging, and large animal models are important for further research efforts. Few severe blast trauma models have been described, which is why we aimed to establish a comprehensive polytrauma model in accordance with the criteria of the Berlin definition of polytrauma and with a survival time of > 2 h. Multiple blast injuries to the groin and abdomen were combined with hypoperfusion, respiratory and metabolic acidosis, hypoventilation, hypothermia and inflammatory response. The model was compared to lung contusion and haemorrhage.

METHODS

16 landrace swine (mean weight 60.5 kg) were randomized to "control" (n = 5), "chest trauma/hem" by lung contusion and class II haemorrhage (n = 5), and "blast polytrauma" caused by multiple blast injuries to the groin and abdomen, class II haemorrhage, lipopolysaccharide (LPS) infusion and hypothermia 32 °C (n = 6).

RESULTS

The blast polytrauma group had an Injury Severity Score of 57 which resulted in haemodynamic shock, hypothermia, respiratory and metabolic acidosis and inflammatory response. The chest trauma/hem group had an Injury Severity Score of 9 and less profound physiologic effects. Physiologic parameters presented a dose-response relationship corresponding to the trauma levels.

CONCLUSION

A comprehensive blast polytrauma model fulfilling the Berlin polytrauma criteria, with a high trauma load and a survival time of > 2 h was established. A severe, but consistent, injury profile was accomplished enabling the addition of experimental interventions in future studies, particularly of immediate resuscitation efforts including whole blood administration, trauma packing and haemostasis.

Evaluation of the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) in animal models

OBJECTIVES

Acquired coagulopathy may be associated with bleeding risk. Approaches to restore haemostasis include administration of coagulation factor concentrates, but there are concerns regarding potential prothrombotic risk. The present study assessed the prothrombotic potential of four-factor prothrombin complex concentrate (4F-PCC) versus activated PCC (aPCC) and recombinant factor VIIa (rFVIIa), using three preclinical animal models.

METHODS

The first model was a modified Wessler model of venous stasis-induced thrombosis in rabbit, focusing on dilutional coagulopathy; the second model employed the same system but focused on direct oral anticoagulant reversal (i.e. edoxaban). The third model assessed the prothrombotic impact of 4F-PCC, aPCC and rFVIIa in a rat model of ferric chloride-induced arterial thrombosis.

RESULTS

In the first model, thrombi were observed at aPCC doses ≥10 IU/kg (therapeutic dose 100 IU/kg) and rFVIIa doses ≥50 μg/kg (therapeutic dose 90 μg/kg), but not 4F-PCC 50 IU/kg (therapeutic dose 50 IU/kg). The impact of 4F-PCC (up to 300 IU/kg) on thrombus formation was evident from 10 minutes post-administration, but not at 24 hours post-administration; this did not change with addition of tranexamic acid and/or fibrinogen concentrate. 4F-PCC-induced thrombus formation was lower after haemodilution versus non-haemodilution. In the second model, no prothrombotic effect was confirmed at 4F-PCC 50 IU/kg. The third model showed lower incidence of thrombus formation for 4F-PCC 50 IU/kg versus aPCC (50 U/kg) and rFVIIa (90 μg/kg).

CONCLUSIONS

These results suggest that 4F-PCC has a low thrombotic potential versus aPCC or rFVIIa, supporting the clinical use of 4F-PCC for the treatment of coagulopathy-mediated bleeding.

Prothrombin Complex Concentrate-induced Disseminated Intravascular Coagulation Can Be Prevented by Coadministering Antithrombin in a Porcine Trauma Model

BACKGROUND

The risk of thromboembolic complications with prothrombin complex concentrates (PCCs) appears low when used for reversal of vitamin K antagonists but might be different in other indications (e.g., trauma). A difference in risk could arise from the plasma ratio of pro- versus anticoagulant proteins. This study used a porcine trauma model to investigate combined treatment with PCC and antithrombin. The hypothesis was that antithrombin can modulate prothrombotic effects and prevent adverse events of PCC.

METHODS

Nine treatment groups (n = 7 per group) were included: control (placebo), PCC (50 IU/kg), PCC plus antithrombin (three groups, with antithrombin doses of 12.5, 25, or 50 IU/kg), fibrinogen concentrate (100 mg/kg) plus PCC, fibrinogen concentrate plus PCC plus antithrombin dose of 50 IU/kg, tranexamic acid (15 mg/kg) plus fibrinogen concentrate plus PCC, and tranexamic acid plus fibrinogen concentrate plus PCC plus antithrombin dose of 50 IU/kg. In each group, bilateral femur fractures and thorax contusion were followed 60 min later by blunt liver injury. Study treatment was then administered, and animals were subsequently observed for 210 min.

RESULTS

Total blood loss (mean ± SD) was statistically significantly lower in all three PCC plus antithrombin groups (PCC plus antithrombin dose of 50 IU/kg, 672 ± 63 ml; PCC plus antithrombin dose of 25 IU/kg, 535 ± 72 ml; and PCC plus antithrombin dose of 12.5 IU/kg, 538 ± 50 ml) than in the PCC group (907 ± 132 ml), which in turn had statistically significantly reduced bleeding versus the control group (1,671 ± 409 ml). Signs of disseminated intravascular coagulation were apparent with PCC monotherapy, and early deaths occurred with fibrinogen concentrate plus PCC, attributable to pulmonary emboli. Antithrombin was protective against both of these effects: signs of disseminated intravascular coagulation were absent from the PCC plus antithrombin groups, and there were no early deaths in the group with fibrinogen concentrate plus PCC plus antithrombin dose of 50 IU/kg.

CONCLUSIONS

According to this trauma model, 50 IU/kg PCC increases the risk of disseminated intravascular coagulation and other thromboembolic complications, most notably when coadministered with fibrinogen concentrate. The addition of antithrombin appears to reduce this risk.

Prothrombin, alone or in complex concentrates or plasma, reduces bleeding in a mouse model of blood exchange-induced coagulopathy

Prothrombin complex concentrates (PCC) are fractionated plasma protein drugs that reverse warfarin anticoagulation. PCC may control more general bleeding. We sought to identify the dominant procoagulant factor in PCC in vivo. We tested PCC or coagulation factor (F) treatment in CD1 mice made coagulopathic by exchange of whole blood for washed red cells. Anesthetized mice were transfused with murine fresh-frozen plasma (mFFP), PCC, mixtures of human vitamin K-dependent proteins (VKDP) (prothrombin, FVII, FIX, or FX), or purified single human VKDP, immediately prior to tail transection (TT), liver laceration (LL), or intravascular laser injury (ILI). Plasma donor mice were treated with vehicle or control antisense oligonucleotide (ASO-CON) or ASO specific for prothrombin (FII) (ASO-FII) to yield mFFP or ASO-CON mFFP or ASO-FII mFFP. Blood losses were determined spectrophotometrically (TT) or gravimetrically (LL). Thrombus formation was quantified by intravital microscopy of laser-injured arterioles. PCC or four factor- (4F-) VKDP or prothrombin significantly reduced bleeding from TT or LL. Omission of prothrombin from 4F-VKDP significantly reduced its ability to limit bleeding. Mice transfused with ASO-FII mFFP demonstrated inferior haemostasis versus those transfused with ASO-FII following TT, LL, or ILI. Prothrombin is the dominant procoagulant component of PCC and could limit bleeding in trauma.

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.

Recombinant human prothrombin (MEDI8111) combined with fibrinogen dose-dependently improved survival time and reduced blood loss in a porcine model of dilutional coagulopathy with uncontrolled bleeding

: Uncontrolled bleeding due to trauma and coagulopathy is an area with high unmet medical need and high mortality rate. Treatment recommendations focus on transfusion of blood components while optimal therapy to improve coagulation remains to be established. The haemostatic effect of 2, 4 and 8 mg/kg recombinant prothrombin (MEDI8111) co-administered with 100 mg/kg fibrinogen (n = 7-8) was investigated in a porcine model of dilutional coagulopathy with uncontrolled bleeding. Vehicle (n = 11), fibrinogen alone (100  mg/kg , n = 15) were included as controls. Dilutional coagulopathy was induced by replacing ∼75% of the blood volume with hydroxyethyl starch and a standardized liver incision was made followed by intravenous administration of study compounds. Survival time and blood loss were determined up to 120 min after liver incision. Rotational thromboelastometry (ROTEM EXTEM), prothrombin time (PT), thrombin--antithrombin complex and thrombin generation were measured at baseline, after dilution and 10, 40, 80 and 120 min after compound administration. Administration of MEDI8111+fibrinogen improved haemostasis, decreased blood loss and dose-dependently improved survival time compared to fibrinogen. All pigs receiving a dose of 8 mg/kg MEDI8111+fibrinogen, which restored normal prothrombin concentration, survived to the end of the experiment with close to normal haemostasis as measured by PT and ROTEM EXTEM CT. Administration of fibrinogen and MEDI8111 was sufficient to improve survival time and haemostasis in severely coagulopathic pigs. The dose-dependent haemostatic improvement observed with MEDI8111 administration suggests that prothrombin concentration was rate limiting for coagulation.

Reversal of dabigatran anticoagulation ex vivo: Porcine study comparing prothrombin complex concentrates and idarucizumab

Urgent surgery or life-threatening bleeding requires prompt reversal of the anticoagulant effects of dabigatran. This study assessed the ability of three- and four-factor prothrombin complex concentrate (PCC) and idarucizumab (specific antidote for dabigatran) to reverse the anticoagulant effects of dabigatran in a porcine model of trauma. Twelve animals were given dabigatran etexilate (DE) orally and dabigatran intravenously, before infliction of trauma. Six animals received tranexamic acid plus fibrinogen concentrate 12 minutes post-injury. Six PCCs (each 30 and 60 U/kg) and idarucizumab (30 and 60 mg/kg) were added to blood samples ex vivo. Coagulation was assessed by several coagulation assays. All coagulation parameters were altered after dabigatran infusion (plasma level: 442 ± 138 ng/ml). Both threeand four-factor PCCs mostly or completely reversed the effects of dabigatran on thromboelastometry variables and PT but not on aPTT. Idarucizumab neutralised plasma concentrations of dabigatran, and reversed the effects of the drug on coagulation variables. Thrombin generation showed dose-dependent over-correction following the addition of PCC, implying that elevated levels of thrombin are required to overcome dabigatran-induced coagulopathy. In contrast, treatment with idarucizumab returned thrombin generation to baseline levels. Following trauma, therapy with tranexamic acid plus fibrinogen improved correction of coagulation parameters by PCC, and thromboelastometry parameters by idarucizumab. All investigated PCCs improved dabigatran- and trauma-induced coagulopathy to a similar degree. In conclusion, this study shows that three- and four-factor PCCs are similarly effective for dabigatran reversal. Idarucizumab also reversed the effects of dabigatran and, unlike PCCs, was not associated with over-correction of thrombin generation.

Note: This study was performed at the RWTH Aachen University Hospital, Pauwelsstrasse 30, D-52074 Aachen, Germany.

Hemostatic Therapy Using Tranexamic Acid and Coagulation Factor Concentrates in a Model of Traumatic Liver Injury

BACKGROUND

The potential clinical benefits of targeted therapy with coagulation factor concentrates (e.g., fibrinogen) and antifibrinolytic agents (e.g., tranexamic acid [TXA]) for the treatment of trauma-induced coagulopathy are increasingly recognized. We hypothesized that human fibrinogen concentrate (FC) and prothrombin complex concentrate (PCC), administered as combined therapy with TXA, would provide additive effects for reducing blood loss in an animal trauma model.

METHODS

Thirty-six pigs were subjected to 2 consecutive blunt liver injuries, resulting in severe hemorrhagic shock and coagulopathy. Intervention comprised saline (control group); TXA (15 mg kg, TXA group); TXA and FC (90 mg kg, TXA-FC); or TXA, FC, and PCC (20 U kg, TXA-FC-PCC). Blood loss, thromboelastometry (ROTEM), measures of thrombin generation, platelet activation, and global coagulation variables were monitored for 4 hours. Tissue sections were examined to determine the occurrence of thromboembolic events.

RESULTS

Total blood loss was similar in the TXA-FC and TXA-FC-PCC groups (mean ± SD: 1012 ± 86 mL and 1037 ± 118 mL, respectively; P = 1.000). These values were both lower (P < 0.001) than the TXA group (1579 ± 306 mL). Blood loss in all 3 intervention groups was lower (P < 0.001) than in the control group (2376 ± 478 mL). After trauma and resuscitation, but before study intervention, plasma fibrinogen levels were severely depleted (median for the whole study population: 66 mg dL; interquartile range: 51-108 mg dL) and clot strength was decreased (EXTEM whole-blood maximum clot firmness [MCF]: 53 ± 5 mm). Compared with controls, TXA inhibited fibrinolysis and stabilized MCF and clotting time. The addition of FC restored and stabilized hemostasis to a greater extent than TXA alone; the addition of PCC had no statistically significant impact on blood loss, clot strength (MCF), or clotting time, but it increased thrombin generation. There were no significant differences among the study groups regarding platelet activation. No thrombi or microthrombi were observed in any group at necropsy.

CONCLUSIONS

The early use of TXA and FC reduced blood loss and improved coagulation measurements in a porcine model of blunt liver injury and hemorrhagic shock. FC, administered in addition to TXA, was highly effective in reducing blood loss. The lack of statistically significant reduction in blood loss when PCC was added to TXA and FC may be attributable to the absence of thrombin generation impairment in this model.

Coagulation Management in Jersey Calves: An ex vivo Study

OBJECTIVE

Jersey calves are frequently used as an experimental animal model for in vivo testing of cardiac assist devices or orthopedic implants. In this ex vivo study, we analyzed the coagulation system of the Jersey calves and the potential of human-based coagulation management to circumvent perioperative bleeding complications during surgery. Experimental Procedure: Blood from 7 Jersey calves was subjected to standard laboratory tests and thromboelastometry analysis. An ex vivo model of dilutional coagulopathy was used to study the effects of fibrinogen or prothrombin complex concentrate supplementation. Fibrinolysis was induced with tissue plasminogen activator to identify potential therapeutic strategies involving tranexamic acid or aprotinin. Furthermore, anticoagulation strategies were evaluated by incubating the blood samples with dabigatran or rivaroxaban.

RESULTS

Baseline values for thromboelastometry and standard laboratory parameters, including prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin III, and D-dimers, were established. Fifty percent diluted blood showed a statistically significant impairment of hemostasis. The parameters significantly improved after the administration of fibrinogen or prothrombin complex concentrate. Tranexamic acid and aprotinin ameliorated tissue plasminogen activator-induced fibrinolysis. Both dabigatran and rivaroxaban significantly prolonged the coagulation parameters.

CONCLUSIONS

In this ex vivo study, coagulation factors, factor concentrate, antifibrinolytic reagents, and anticoagulants regularly used in the clinic positively impacted coagulation parameters in Jersey calf blood.

Fibrinogen concentrate improves survival during limited resuscitation of uncontrolled hemorrhagic shock in a Swine model

The purpose of this study was to evaluate the effect of fibrinogen concentrate, as a hemostatic agent, on limited resuscitation of uncontrolled hemorrhagic shock. We use a swine model of hemorrhagic shock with free bleeding from a 4-mm aortic tear to test the effect of adding a one-time dose of fibrinogen concentrate given at the onset of limited fluid resuscitation. Immature female swine were anesthetized and subjected to catheter hemorrhage and aortic tear to induce uniform hemorrhagic shock. Animals (n = 7 per group) were then randomized to receive (i) no fluid resuscitation (neg control) or (ii) limited resuscitation in the form of two boluses of 10 mL/kg of 6% hydroxyethyl starch solution given 30 min apart (HEX group), or (iii) the same fluid regimen with one dose of 120-mg/kg fibrinogen concentrate given with the first hydroxyethyl starch bolus (FBG). Animals were then observed for a total of 6 h with aortic repair and aggressive resuscitation with shed blood taking place at 3 h. Survival to 6 h was significantly increased with FBG (7/8, 86%) versus HEX (2/7, 29%) and neg control (0/7, 0%) (FBG vs. HEX, Kaplan-Meier log-rank P = 0.035). Intraperitoneal blood loss adjusted for survival time was increased in HEX (0.4 mL/kg per minute) when compared with FBG (0.1 mg/kg per minute, P = 0.047) and neg control (0.1 mL/kg per minute, P = 0.041). Systemic and cerebral hemodynamics also showed improvement with FBG versus HEX. Fibrinogen concentrate may be a useful adjunct to decrease blood loss, improve hemodynamics, and prolong survival during limited resuscitation of uncontrolled hemorrhagic shock.

Evaluation of fibrinogen concentrates and prothrombin complex concentrates on coagulation changes in a hypothermic in vitro model using thromboelastometry and thromboelastography

BACKGROUND

Hypothermic coagulopathy is very challenging in bleeding trauma patients. Therefore, we decided to evaluate the efficacy of fibrinogen and prothrombin complex in 30°C hypothermia in vitro to investigate if higher levels of fibrinogen and prothrombin complex concentrate can compensate for the hypothermic effect on coagulation as measured by thromboelastometry/thromboelastography.

METHODS

Blood samples were obtained from 12 healthy volunteers (six men and six women) in our study. Measurements were performed at 37°C and 30°C simultaneously, then at 30°C with adding fibrinogen and prothrombin complex and in the last step samples with added coagulation factors were warmed back to 37°C.

RESULTS

We found that 30°C hypothermic coagulopathy can be detected both by thromboelastometry and thromboelastography. Hypothermic coagulopathy can be restored by fibrinogen to the point where the results do not significantly differ from 37°C values (p > 0.05). After warming the sample with fibrinogen to 37°C, the thrombodynamic potential index was not significantly different from baseline (p > 0.05), although there was a trend to prothrombotic status. The addition of prothrombin complex concentrate to 30°C hypothermic sample was not able to correct hypothermic coagulopathy in vitro.

CONCLUSIONS

Coagulopathy caused by the 30°C hypothermia in vitro model can be corrected by fibrinogen concentrate compared to prothrombin complex concentrate. In spite of a tendency to prothrombotic status, this was not significant with the use of the recommended dose of fibrinogen even after warming the blood to 37°C. However, measurement performed at 37°C seems to be safer than at 30°C.

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.

Measurement of dabigatran in standardly used clinical assays, whole blood viscoelastic coagulation, and thrombin generation assays

Dabigatran, a direct thrombin inhibitor, is increasingly used clinically as one of the new oral anticoagulants. This review summarizes the assays available to measure its activity and includes the relative sensitivity of the different assays for this agent. In addition to plasma-based clotting tests, assays commonly used in surgical/emergency settings, such as activated clotting time and thromboelastometry/thromboelastography, are reviewed. In addition, the thrombin generation assay is discussed as an important method to determine the potential risk of thrombosis or bleeding and its relevance to the measurement of direct thrombin inhibitors.

Endogenous thrombin potential following hemostatic therapy with 4-factor prothrombin complex concentrate: a 7-day observational study of trauma patients

Introduction

Purified prothrombin complex concentrate (PCC) is increasingly used as hemostatic therapy for trauma-induced coagulopathy (TIC). However, the impact of PCC administration on coagulation status among patients with TIC has not been adequately investigated.

Methods

In this observational, descriptive study, data relating to thrombin generation were obtained from plasma samples gathered prospectively from trauma patients upon emergency room (ER) admission and over the following 7 days. Standard coagulation tests, including measurement of antithrombin (AT) and fibrinogen, were performed. Three groups were investigated: patients receiving no coagulation therapy (NCT group), patients receiving fibrinogen concentrate only (FC group), and patients treated with PCC and fibrinogen concentrate (FC-PCC group).

Results

The study population (77 patients) was predominantly male (84.4%); mean age was 40 ± 15 years and mean injury severity score was 25.6 ± 12.7. There were no significant differences between the three study groups in thrombin-related parameters upon ER admission. Endogenous thrombin potential (ETP) was significantly higher in the FC-PCC group compared with the NCT group on days 1 to 4 and the FC group on days 1 to 3. AT levels were significantly lower in the FC-PCC group from admission until day 3 (versus FC group) or day 4 (versus NCT group). Fibrinogen increased over time, with no significant between-group differences after ER admission. Despite ETP being higher, prothrombin time and activated partial thromboplastin time were significantly prolonged in the FC-PCC group from admission until day 3 to 4.

Conclusions

Treatment with PCC increased ETP for several days, and patients receiving PCC therapy had low AT concentrations. These findings imply a potential pro-thrombotic state not reflected by standard coagulation tests. This is probably important given the postoperative acute phase increase in fibrinogen levels, although studies with clinical endpoints are needed to ascertain the implications for patient outcomes. We recommend careful use of PCC among trauma patients, with monitoring and potentially supplementation of AT.

Relevance of induced and accidental hypothermia after trauma-haemorrhage-what do we know from experimental models in pigs?

Recent experimental research has either focused on the role of accidental hypothermia as part of the lethal triad after trauma or tried to elucidate the effects of therapeutically induced hypothermia on the posttraumatic course. Induced hypothermia seems to reduce the mortality in experimental models of trauma-haemorrhage. As potential mechanisms, a decrease of cellular metabolism, beneficial effects on haemodynamic function and an attenuation of the inflammatory response have been described. However, negative side effects of hypothermia have to be considered, such as impairment of the coagulatory function and immunosuppressive effects. Furthermore, the optimal strategy for the induction of hypothermia (magnitude, duration, timing, cooling rate, etc.) and subsequent rewarming remains unclear. Nevertheless, this piece of information is essential before considering hypothermia as a treatment strategy for severely injured patients. This review aims to elaborate the differences between accidental and induced hypothermia and to summarize the current knowledge of the potential therapeutic use of induced hypothermia suggested in porcine models of trauma-haemorrhage.

Trauma hemostasis and oxygenation research position paper on remote damage control resuscitation: definitions, current practice, and knowledge gaps

The Trauma Hemostasis and Oxygenation Research Network held its third annual Remote Damage Control Resuscitation Symposium in June 2013 in Bergen, Norway. The Trauma Hemostasis and Oxygenation Research Network is a multidisciplinary group of investigators with a common interest in improving outcomes and safety in patients with severe traumatic injury. The network's mission is to reduce the risk of morbidity and mortality from traumatic hemorrhagic shock, in the prehospital phase of resuscitation through research, education, and training. The concept of remote damage control resuscitation is in its infancy, and there is a significant amount of work that needs to be done to improve outcomes for patients with life-threatening bleeding secondary to injury. The prehospital phase of resuscitation is critical in these patients. If shock and coagulopathy can be rapidly identified and minimized before hospital admission, this will very likely reduce morbidity and mortality. This position statement begins to standardize the terms used, provides an acceptable range of therapeutic options, and identifies the major knowledge gaps in the field.

Prothrombin complex concentrates and a specific antidote to dabigatran are effective ex-vivo in reversing the effects of dabigatran in an anticoagulation/liver trauma experimental model

Introduction

New oral anticoagulants are effective alternatives to warfarin. However, no specific reversal agents are available for life-threatening bleeding or emergency surgery. Using a porcine model of trauma, this study assessed the ability of prothrombin complex concentrate (PCC), activated PCC (aPCC), recombinant FVIIa (rFVIIa) and a specific antidote to dabigatran (aDabi-Fab) to reverse the anticoagulant effects of dabigatran.

Methods

Dabigatran etexilate (DE) was given orally for 3 days (30 mg/kg bid) and intravenously on day 4 to achieve consistent, supratherapeutic concentrations of dabigatran. Blood samples were collected at baseline, after oral DE, after intravenous dabigatran, and 60 minutes post-injury. PCC (30 and 60 U/kg), aPCC (30 and 60 U/kg), rFVIIa (90 and 180 μg/kg) and antidote (60 and 120 mg/kg) were added to blood samples ex-vivo. Coagulation was assessed by thromboelastometry, global coagulation assays and diluted thrombin time.

Results

Plasma concentrations of dabigatran were 380 ± 106 ng/ml and 1423 ± 432 ng/ml after oral and intravenous administration, respectively, and all coagulation parameters were affected by dabigatran. Both PCCs and aDabi-Fab, but not rFVIIa, reversed the effects of dabigatran on thromboelastometry parameters and prothrombin time. In contrast, aPTT was only normalised by aDabi-Fab. Plasma concentration (activity) of dabigatran remained elevated after PCC and rFVIIa therapy, but was not measureable after aDabi-Fab.

Conclusion

In conclusion, PCC and aPCC were effective in reducing the anticoagulant effects of dabigatran under different conditions, while aDabi-Fab fully corrected all coagulation measures and decreased the plasma concentration of dabigatran below the limit of detection. No significant effects were observed with rFVIIa.

Fibrin patch in a pig model with blunt liver injury under severe hypothermia

BACKGROUND

Rapid control of hemorrhage is one of the key aspects in trauma handling. To cope with bleeding, local hemostatic approaches are useful, along with surgical and systemic homostatic therapy. In this experimental study, we investigated the efficacy of a fibrinogen/thrombin containing collagen patch (TachoSil) in a coagulopathic pig model with blunt liver trauma under severe hypothermia.

METHODS

Eighteen anesthetized pigs underwent hemodilution by exchanging 70% of the blood volume with Ringer Lactate solution and hydroxyethyl starch 130/0.4 (1:1). Ten minutes after induction of a grade III blunt liver trauma, the animals randomly received treatment with TachoSil (FT-patch, n = 9) or a collagen patch (Tachotop, control group, n = 9). Blood loss, hemodynamics, and coagulation parameters were observed for 2 h. To confirm the consistency of liver trauma, pathologic examination of the liver tissue was performed.

RESULTS

Hypothermia (33.5°C ± 0.5°C) and hemodilution led to severe coagulopathy as measured by thromboelastometry and coagulation parameters. After trauma and patch application, thromboelastometry and coagulation parameters in the control group showed further deterioration compared with the stable parameters in the FT-patch group. The total blood loss was significantly reduced in the FT-patch group (FT-patch: 1195 mL; control group: 2495 mL; P < 0.001). Concordantly, the control animals were hemodynamically jeopardized to a higher degree. Microscopy confirmed a similar degree of liver injury.

CONCLUSIONS

Despite severe hypothermia and coagulopathy, TachoSil provided effective hemorrhage control in pigs with blunt liver injury. Therefore, TachoSil demonstrated usefulness as an additional early therapy in cases of uncontrolled bleeding following severe trauma.

Thrombin generation capacity of prothrombin complex concentrate in an in vitro dilutional model

Background

The use of PCC for the treatment of trauma-induced coagulopathy potentially increase the risk of thromboembolism and disseminated intravascular coagulation, which is addressed to an imbalance of both pro- and anticoagulants. As PCCs differ in composition, we used an in vitro dilutional approach to assess the overall thrombin generation of five different PCCs through various laboratory assays.

Methods

The vitamin K-dependent coagulation factors, heparin, and antithrombin were assessed in five commercially available PCCs. The procoagulant potential of the PCCs was assessed in plasma and whole blood from 4 healthy donors by means of classical coagulation assays, thrombin generation assay and thromboelastometry. In order to reflect coagulopathy, whole blood was diluted to 80, 60, 40, and 20% with Ringer’s lactate solution.

Results

The five different PCCs were characterised by comparable levels of factors II, VII, IX and X (all around 20–30 IU/mL), whereas the heparin (0 to 17.6 IU/mL) and antithrombin (0.06 to 1.29 IU/mL) levels were remarkably different between manufactures. In vitro dilution of blood induced a prolongation of the PT and aPTT, and attenuation of thrombin generation and ExTem induced thromboelastometry. Overall, non- or low-heparin containing PCCs restored the in vitro dilutional coagulopathy, whereas PCCs containing heparin have an anticoagulant effect. The thrombin generation assay showed to be the most sensitive method for assessment of PCC effects.

Conclusions

This study shows that most available PCCs are not balanced regarding their pro- and anticoagulants. The effect of measured differences in thrombin generation among different PCCs requires further investigations to elaborate the clinical meaning of this finding in the treatment of trauma induced coagulopathy.

Resuscitation and transfusion management in trauma patients: emerging concepts

PURPOSE OF REVIEW

Severe trauma is associated with hemorrhage, coagulopathy and transfusion of blood and blood products, all associated with considerable mortality and morbidity. The aim of this review is to focus on resuscitation, transfusion strategies and the management of bleeding in trauma as well as to emphasize on why coagulation has to be monitored closely and to discuss the rationale of modern and future transfusion strategies.

RECENT FINDINGS

Coagulopathy and uncontrolled bleeding remain leading causes of death in trauma, lead to blood transfusions and increased mortality as it has been recently shown that blood transfusion per se results in an adverse outcome. In the last years, damage control resuscitation, a combination of permissive hypotension, hemostatic resuscitation and damage control surgery, has been introduced to treat severely traumatized patients in hemorrhagic shock. Goals of treatment in trauma patients remain avoiding metabolic acidosis, hypothermia, treating coagulopathy and stabilizing the patient as soon as possible. The place of colloids and crystalloids in trauma resuscitation as well as the role of massive transfusion protocols with a certain FFP : RBC ratio and even platelets have to be reevaluated.

SUMMARY

Close monitoring of bleeding and coagulation in trauma patients allows goal-directed transfusions and thereby optimizes the patient's coagulation, reduces the exposure to blood products, reduces costs and may improve clinical outcome.

Coagulation management

PURPOSE OF REVIEW

Trauma-induced coagulopathy is a frequent complication in severely injured patients. To correct coagulopathy and restore haemostasis, these patients have traditionally been treated with fresh frozen plasma, but in the last decade, there has been a shift from empirical therapy to targeted therapy with coagulation factor concentrates and other haemostatic agents. This review highlights emerging therapeutic options and controversial topics.

RECENT FINDINGS

Early administration of the antifibrinolytic medication tranexamic acid was shown in the multicentre CRASH-2 trial to be an effective and inexpensive means of decreasing blood loss. Numerous retrospective and experimental studies have shown that the use of coagulation factor concentrates decreases blood loss and may be useful in reducing the need for transfusion of allogeneic blood products. In particular, early use of fibrinogen concentrate and thrombin generators has a positive impact on haemostasis. However, the use of prothrombin complex concentrate to correct trauma-induced coagulopathy has also been associated with a potential risk of serious adverse events.

SUMMARY

Current evidence in trauma resuscitation indicates a potential role for coagulation factor concentrates and other haemostatic agents in correcting trauma-induced coagulopathy. Despite a shift towards such transfusion strategy, there remains a shortage of data to support this approach.

[Dealing with massive bleeding and associated perioperative coagulopathy: recommendations for action of the German Society of Anaesthesiology and Intensive Care Medicine]

Massive bleeding with coagulopathy and hemorrhagic shock poses a potential threat to life in numerous clinical settings. Optimal treatment including the prevention of exsanguination necessitates a standardized and interdisciplinary approach. Several studies have shown the importance of massive transfusion protocols and standardized coagulation algorithms to improve survival of severely bleeding patients and to avoid secondary complications. Thus, the Helsinki declaration for patient safety in anesthesiology demands the implementation of clinical practice guidelines for the treatment of patients requiring massive transfusion. This paper introduces a standardized algorithm for the treatment of patients with massive bleeding which was developed in consensus with the German Society of Anaesthesiology and Intensive Care Medicine (DGAI).

Point of care devices for assessing bleeding and coagulation in the trauma patient

Severe trauma is associated with bleeding, coagulopathy, and transfusion of blood and blood products, all contributing to higher rates of morbidity and mortality. The aim of this review is to focus on point-of-care devices to monitor coagulation in trauma. Close monitoring of bleeding and coagulation as well as platelet function in trauma patients allows goal-directed transfusion and an optimization of the patient's coagulation, reduces the exposure to blood products, reduces costs, and probably improves clinical outcome. Noninvasive hemoglobin measurements are not to be used in trauma patients due to a lack in specificity and sensitivity.