Correction of hypothermic and dilutional coagulopathy with concentrates of fibrinogen and factor XIII: an in vitro study with ROTEM

Cryoprecipitate transfusion in trauma patients attenuates hyperfibrinolysis and restores normal clot structure and stability: Results from a laboratory sub-study of the FEISTY trial

BACKGROUND

Fibrinogen is the first coagulation protein to reach critical levels during traumatic haemorrhage. This laboratory study compares paired plasma samples pre- and post-fibrinogen replacement from the Fibrinogen Early In Severe Trauma studY (FEISTY; NCT02745041). FEISTY is the first randomised controlled trial to compare the time to administration of cryoprecipitate (cryo) and fibrinogen concentrate (Fg-C; Riastap) in trauma patients. This study will determine differences in clot strength and fibrinolytic stability within individuals and between treatment arms.

METHODS

Clot lysis, plasmin generation, atomic force microscopy and confocal microscopy were utilised to investigate clot strength and structure in FEISTY patient plasma.

RESULTS

Fibrinogen concentration was significantly increased post-transfusion in both groups. The rate of plasmin generation was reduced 1.5-fold post-transfusion of cryo but remained unchanged with Fg-C transfusion. Plasminogen activator inhibitor 1 activity and antigen levels and Factor XIII antigen were increased post-treatment with cryo, but not Fg-C. Confocal microscopy analysis of fibrin clots revealed that cryo transfusion restored fibrin structure similar to those observed in control clots. In contrast, clots remained porous with stunted fibres after infusion with Fg-C. Cryo but not Fg-C treatment increased individual fibre toughness and stiffness.

CONCLUSIONS

In summary, our data indicate that cryo transfusion restores key fibrinolytic regulators and limits plasmin generation to form stronger clots in an ex vivo laboratory study. This is the first study to investigate differences in clot stability and structure between cryo and Fg-C and demonstrates that the additional factors in cryo allow formation of a stronger and more stable clot.

In Vivo Effects of Balanced Crystalloid or Gelatine Infusions on Functional Parameters of Coagulation and Fibrinolysis: A Prospective Randomized Crossover Study

Prudent administration of fluids helps restore or maintain hemodynamic stability in the setting of perioperative blood loss. However, fluids may arguably exacerbate the existing coagulopathy. We sought to investigate the influence of balanced crystalloid and synthetic gelatine infusions on coagulation and fibrinolysis in healthy volunteers. This prospective randomized crossover study included 25 males aged 18–30 years. Infusions performed included 20 mL/kg of a balanced crystalloid solution (Optilyte^®) or 20 mL/kg of gelatine 26.500 Da (Geloplasma^®) in a random order over a period of 2 weeks. Laboratory analysis included conventional coagulation parameters and rotational thromboelastometry (ROTEM) assays. We confirmed a decrease in fibrinogen concentration and the number of platelets, and prolongation of PT after infusions. Compared to baseline values, differences in the ROTEM assays’ results after infusions signified the decrease in coagulation factors and fibrinogen concentration, causing impaired fibrin polymerization and clot structure. The ROTEM indicator of clot lysis remained unaffected. In the case of both Optilyte^® and Geloplasma^®, the results suggested relevant dilution. Gelatine disrupted the process of clot formation more than balanced crystalloid. Infusions of both crystalloid and saline-free colloid solutions causing up to 30% blood dilution cause significant dilution of the coagulation factors, platelets, and fibrinogen. However, balanced crystalloid infusion provides less infusion-induced coagulopathy compared to gelatine.

The impact of crystalloid versus colloid on coagulation as measured by thromboelastometry in term parturients: an in vitro study

OBJECTIVE

A pilot study to examine the impact of crystalloid versus albumin hemodilution in vitro on coagulation using thromboelastometry in pregnant patients.

METHODS

This prospective, observational pilot study included seventy-six pregnant patients at term (≥37 weeks) without history of bleeding or clotting disorder or on anticoagulation. Blood was collected and diluted with either Plasma-Lyte or albumin at the following levels: 0%, 20%, 25%, 30%, 35%, 40%, 45%, 55%, 60%, 65%, 70%, 75%, 80%. Thromboelastometry was performed to assess for coagulation changes.

RESULTS

There was a small, statistically significant difference in the FIBTEM A5 between the Plasma-Lyte and albumin samples. However, the predicted probability of coagulopathy, using FIBTEM A5 less than 12 mm, was not different between the groups at any dilution. There was no difference in EXTEM clotting time at low-moderate levels of hemodilution. At dilutions above 40%, the albumin group had a significantly greater prolongation in clotting time compared to the Plasma-Lyte group.

CONCLUSION

When albumin is used at low-moderate levels of hemodilution in vitro in parturients there is no additional risk of coagulopathy compared to hemodilution with crystalloid. Given that colloids are frequently used to restore intravascular volume during massive hemorrhage, these results support that during early stages of hemorrhage, albumin may not contribute to additional coagulopathy beyond that of hemodilution, although further in vivo studies are needed.

Combined Administration of Fibrinogen and Factor XIII Concentrate Does Not Improve Dilutional Coagulopathy Superiorly Than Sole Fibrinogen Therapy: Results of an In-Vitro Thrombelastographic Study

The early administration of fibrinogen has gained wide acceptance for the treatment of major hemorrhage, whereas the substitution of coagulation factor XIII (FXIII) is only supported by a low level of evidence. This study aimed to answer the question of whether a combined therapy of fibrinogen/FXIII substitution performs superiorly to sole fibrinogen administration in the treatment of dilutional coagulopathy. An in-vitro model of massive transfusion was used to compare the effect of combined fibrinogen/FXIII administration to that of sole fibrinogen therapy for the treatment of dilutional coagulopathy. For this purpose, the blood of red blood cell concentrates, fresh frozen plasma, and platelet concentrates were reconstituted in a ratio of 4:4:1, and then diluted with gelatin by 20% and 40%, respectively. Clot formation and stability were analyzed by thrombelastography. Both sole fibrinogen therapy (equivalent to 50 mg/kg) and the combined administration of fibrinogen (equivalent to 50 mg/kg) and FXIII (equivalent to 75 International Units (IU)/kg) increased fibrinogen-dependent mean clot firmness independently of the degree of dilution (20% dilution: 7 (6.3–7.8) mm; 20% dilution fibrinogen: 13.5 (13–17.3) mm; 20% dilution fibrinogen/FXIII: 16.5 (15.3–18.8) mm; 40% dilution: 3 (2–3.8) mm; 40% dilution fibrinogen: 8 (7–11.3) mm; 40% dilution fibrinogen/FXIII: 10 (8.3–11.8) mm; all p < 0.01). However, no differences were identified between the two treatment arms. Compared to fibrinogen therapy, no beneficial effect of the combined administration of fibrinogen and FXIII for the treatment of dilutional coagulopathy was detected in this in-vitro massive transfusion model. The result was independent of the degree of dilution.

In-vitro assessment of the effects of fibrinogen, recombinant factor VIIa and factor XIII on trauma-induced coagulopathy

: Trauma-induced coagulopathy (TIC) occurs commonly as a second event following severe injury. We evaluated the effects of fibrinogen, recombinant factor VIIa and factor XIII on blood clotting and fibrinolysis in an in-vitro TIC model. The TIC model included hemodilution, hyperfibrinolysis, acidosis and hypothermia. The extent of clot formation and fibrinolysis was evaluated using rotational thromboelastometry. Clot strength was increased following spiking the TIC blood with either 1.0 mg/ml fibrinogen, 3.0 μg/ml recombinant factor VIIa or 2.0 IU/ml factor XIII. Maximal effect was achieved by all agents in combination approximating the extent of clot formation to those in normal blood. Fibrinolysis was inhibited by factor XIII, while the reduction was stronger using all agents together. When each of the agents used in two times lower concentrations, clot strength was near to threshold. Fibrinogen and factor XIII but not factor VIIa exerted stimulation of clot strength, whereas synergistic effect of fibrinogen and factor XIII was observed. Maximal effect was achieved combining all agents. The antifibrinolytic effect was observed only by co-administration of fibrinogen, factor XIII and factor VIIa. On the basis of our study, we suggest that stimulation of clot formation and inhibition of fibrinolysis may be achieved by combination of FG, rFVIIa an FXIII using each of them at minimal effective concentration. Taken into consideration, multifactorial TIC pathogenesis, this approach may be preferable for improving coagulopathy than separate blood spiking with the essayed factors at high concentrations.

Biomimetic Strategies To Treat Traumatic Brain Injury by Leveraging Fibrinogen

There were over 27 million new cases of traumatic brain injuries (TBIs) in 2016 across the globe. TBIs are often part of complicated trauma scenarios and may not be diagnosed initially because the primary clinical focus is on stabilizing the patient. Interventions used to stabilize trauma patients may inadvertently impact the outcomes of TBIs. Recently, there has been a strong interest in the trauma community toward administrating fibrinogen-containing solutions intravenously to help stabilize trauma patients. While this interventional shift may benefit general trauma scenarios, fibrinogen is associated with potentially deleterious effects for TBIs. Here, we deconstruct what components of fibrinogen may be beneficial as well as potentially harmful following TBI and extrapolate this to biomimetic approaches to treat bleeding and trauma that may also lead to better outcomes following TBI.

How do external factors contribute to the hypocoagulative state in trauma-induced coagulopathy? - In vitro analysis of the lethal triad in trauma

Background

External factors following trauma and iatrogenic intervention influence blood coagulation and particularly clot formation. In particular, three external factors (in detail dilution via uncritical volume replacement, acidosis and hypothermia), in combination, referred to as the “lethal triad”, substantially aggravate the hypocoagulative state after trauma. Contribution of these external factors to the resulting hypocoagulative state in trauma and especially their influence on primary haemostasis has still not been investigated systematically.

This study aims to assess this contribution to the aggravating hypocoagulative state in trauma-induced coagulopathy (TIC) using an in vitro simulation assay. Emphasis is given to platelet contribution to clot formation and to the investigation of how platelet activation alters under the respective conditions.

Methods

To simulate the conditions of lethal triad in vitro, whole blood samples taken from five healthy volunteers were introduced to the respective conditions. Besides standard coagulation testing, thrombelastometric analysis and differentiated platelet mapping were performed.

Results

All three simulated conditions induced significant impairments of clot formation (clot formation time, CFT; α -angle) and propagation (maximum clot firmness, MCF; Diameter A5-A25), with the highest impact under hypothermia and dilution. Consistently, lethal triad resulted in an additive effect of all conditions. None of the simulated conditions induced a statistically relevant change in coagulation initiation assessed by EXTEM and FIBTEM thrombelastometry.

Platelet contribution to clot formation decreased gradually under the respective conditions, reaching statistical significance for simulated dilution, and attaining its greatest extent under the conditions of lethal triad (Δtrias/baseline 0.59; p = 0.01). Consistent, reduced CD62 expression levels were observed under experimental acidosis (Δacidosis/baseline 0.32; p = 0.006), dilution (Δdilution/baseline 0.34; p = 0.01) and lethal triad (Δlethal triad/baseline 0.24; p = 0.01).

Conclusion

The respective external factors of lethal triad play a pivotal role in the development of coagulopathy, essentially influencing the kinetics of clot formation, and to a varying extent clot diameter, as measured by thrombelastometry. Moreover, impairment of platelet function under the conditions of lethal triad plays a key role in the pathophysiology of TIC, resulting in reduced responsiveness to stimulation with ADP that might also be present after trauma. Our data indicate that impairment of primary haemostasis contribute to the hypocoagulative state in TIC after trauma aggravated by external factors of lethal triad.

Fibrinogen supplementation ex vivo increasesclot firmness comparable to platelet transfusion in thrombocytopenia

BACKGROUND

Fibrinogen concentrate can improve clot firmness and offers a better safety profile than platelet concentrates. Reduction or avoidance of blood transfusions represents a strategy to reduce associated risks. We investigated whether supplementation of fibrinogen concentrate ex vivo can compensate for clot strength as compared with platelet transfusion in vivo METHODS: One hundred patients in need of platelet transfusion (PT) were enrolled. Blood samples were collected immediately before PT and at 1 h and 24 h after PT. Fibrinogen concentrate was added to these citrated whole blood samples at concentrations of 50, 100, 200 and 400 mg kg^-1 and the maximum clot firmness (MCF) was analysed using ROTEM thromboelastometry.

RESULTS

Fibrinogen supplementation increased MCF significantly and dose-dependently before and after PT. The effect of fibrinogen concentrate (equivalent to doses of 100 and 200 mg kg^-1) ex vivo was comparable to that of PT in vivo, whereas 400 mg kg^-1 fibrinogen significantly improved MCF compared with PT (P < 0.001).

CONCLUSIONS

Fibrinogen concentrate can match the effect of PT on MCF in thrombocytopenia. This potential alternative haemostatic intervention should be evaluated in clinical trials.

Short-term recovery pattern of plasma fibrinogen after cardiac surgery: A prospective observational study

Low plasma fibrinogen level is common after cardiopulmonary bypass (CPB). Current substitution practice with fibrinogen concentrate generally follows a single measurement and cut-off values from the literature, whereas early postoperative endogenous fibrinogen kinetics is incompletely described and widely disregarded. The aim of this study was to determine the short-term recovery pattern of plasma fibrinogen after CPB weaning. Our hypothesis was that in the absence of surgical bleeding, CPB-induced hypofibrinogenemia would resolve spontaneously and predictably within a few hours. In a prospective, observational study of 26 patients undergoing conventional CPB (cCPB) or minimally invasive extracorporeal circulation (MiECC), Clauss fibrinogen level (C-FIB) was determined at 10 closely spaced time points after protamine administration. Primary endpoint was the time to recovery of post-CPB fibrinogen levels to ≥1.5 g/L. C-FIB reached its nadir after protamine administration corresponding to 62 ± 5% (mean ± SD) of the baseline level after cCPB and 68 ± 7% after MiECC (p = 0.027 vs. cCPB). C-FIB recovered spontaneously at a nearly constant rate of approximately 0.08 g/L per hour. In all patients, C-FIB was ≥1.5 g/L at 4 hours and ≥2.0 g/L at 13 hours after CPB weaning. Following cardiac surgery with CPB and in the absence of surgical bleeding, spontaneous recovery of normal endogenous fibrinogen levels can be expected at a rate of 0.08 g/L per hour. Administration of fibrinogen concentrate triggered solely by a single-point measurement of low plasma fibrinogen some time after CPB is not justified.

Relative effects of plasma, fibrinogen concentrate, and factor XIII on ROTEM coagulation profiles in an in vitro model of massive transfusion in trauma

Massive traumatic haemorrhage is aggravated through the development of trauma-induced coagulopathy, which is managed by plasma transfusion and/or fibrinogen concentrate administration. It is yet unclear whether these treatments are equally potent in ensuring adequate haemostasis, and whether additional factor XIII (FXIII) administration provides further benefits. In this study, we compared ROTEM whole blood coagulation profiles after experimental massive transfusion with different transfusion regimens in an in vitro model of dilution- and transfusion-related coagulopathy. Healthy donor blood was mixed 1 + 1 with six different transfusion regimens. Each regimen contained RBC, platelet concentrate, and either fresh frozen plasma (FFP) or Ringer's acetate (RA). The regimens were further augmented through addition of a low- or medium-dose fibrinogen concentrate and FXIII. Transfusion with FFP alone was insufficient to maintain tissue-factor activated clot strength, coincidental with a deficiency in fibrin-based clot strength. Fibrinogen concentrate conserved, but did not improve coagulation kinetics and overall clot strength. Only combination therapy with FFP and low-dose fibrinogen concentrate improved both coagulation kinetics and fibrin-based clot strength. Administration of FXIII did not result in an improvement of clot strength. In conclusion, combination therapy with both FFP and low-dose fibrinogen concentrate improved clotting time and produced firm clots, representing a possible preferred first-line regimen to manage trauma-induced coagulopathy when RBC and platelets are also transfused. Further research is required to identify optimal first-line transfusion fluids for massive traumatic haemorrhage.

Monitoring the coagulation status of trauma patients with viscoelastic devices

Coagulopathy is a physiological response to massive bleeding that frequently occurs after severe trauma and is an independent predictive factor for mortality. Therefore, it is very important to grasp the coagulation status of patients with severe trauma quickly and accurately in order to establish the therapeutic strategy. Judging from the description in the European guidelines, the importance of viscoelastic devices in understanding the disease condition of patients with traumatic coagulopathy has been widely recognized in Europe. In the USA, the ACS TQIP Massive Transfusion in Trauma Guidelines proposed by the American College of Surgeons in 2013 presented the test results obtained by the viscoelastic devices, TEG® 5000 and ROTEM®, as the standard for transfusion or injection of blood plasma, cryoprecipitate, platelet concentrate, or anti-fibrinolytic agents in the treatment strategy for traumatic coagulopathy and hemorrhagic shock. However, some studies have reported limitations of these viscoelastic devices. A review in the Cochrane Library published in 2015 pointed out the presence of biases in the abovementioned reports in trauma patients and the absence of a quality study in this field thus far. A quality study on the relationship between traumatic coagulopathy and viscoelastic devices is needed.

In vitro effects of different sources of fibrinogen supplementation on clot initiation and stability in a model of dilutional coagulopathy

OBJECTIVES

To analyse which fibrinogen source may improve coagulation using an in vitro 33% dilutional coagulopathy model.

BACKGROUND

Uncritical volume resuscitation in the context of trauma haemorrhage contributes to the iatrogenic arm of the acute trauma-induced coagulopathy through dilution and depletion of coagulation factors, with fibrinogen reaching critical levels first.

MATERIALS AND METHODS

By using an experimental model of 33% dilutional coagulopathy, we have analysed which fibrinogen source may exert superior effects on improving haemocoagulative capacities and correcting depleted fibrinogen levels. As fibrinogen sources, we supplemented (i) fresh frozen plasma (FFP), (ii) fibrinogen concentrate low-dose (Fib_low ) and (iii) fibrinogen concentrate high-dose (Fib_high ), the latter both in the presence and absence of additional FXIII.

RESULTS

The dilution was associated with decreased haemoglobin and haematocrit levels. Fibrinogen supplementation with fibrinogen-containing formulations led to increased fibrinogen levels (FFP: 172·2 ± 17·4 mg dL^-1 ; Fib_low : 211·5 ± 20·61 mg dL^-1 ; Fib_high : 255·8 ± 21·4 mg dL^-1 ) than in a diluted-only sample (155·5 ± 19·7 mg dL^-1 ). Extrinsically activated assay with tissue factor (EXTEM) clot formation times, α-angles and maximum clot firmness significantly improved in the groups of Fib_low + FXIII (79 ± 12·2 s; 74·3 ± 2·4°; 62 ± 2·3 mm), Fib_high (70·8 ± 10·6 s; 76·2 ± 2·7°; 64·3 ± 2·3 mm) and Fib_high + FXIII (69·8 ± 11·5 s; 77·5 ± 2·7°; 64·33 ± 2·5 mm) compared with the dilution groups (104·2 ± 19 s; 69·7 ± 2·9°; 56·5 ± 3·1 mm). In contrast, rotational thromboelastometric trace (ROTEM) measures of samples supplemented with FFP largely remained unchanged.

CONCLUSION

Fibrinogen concentrates corrected and improved haemodilution-induced changes in blood clotting in vitro. High-dose fibrinogen supplementation was associated with correction and improvement in clot dynamics and stability.

The Effects of Temperature on Clot Microstructure and Strength in Healthy Volunteers

BACKGROUND

Anesthesia, critical illness, and trauma are known to alter thermoregulation, which can potentially affect coagulation and clinical outcome. This in vitro preclinical study explores the relationship between temperature change and hemostasis using a recently validated viscoelastic technique. We hypothesize that temperature change will cause significant alterations in the microstructural properties of clot.

METHODS

We used a novel viscoelastic technique to identify the gel point of the blood. The gel point identifies the transition of the blood from a viscoelastic liquid to a viscoelastic solid state. Furthermore, identification of the gel point provides 3 related biomarkers: the elastic modulus at the gel point, which is a measure of clot elasticity; the time to the gel point (TGP), which is a measure of the time required to form the clot; and the fractal dimension of the clot at the gel point, df, which quantifies the microstructure of the clot. The gel point measurements were performed in vitro on whole blood samples from 136 healthy volunteers over a temperature range of 27°C to 43°C.

RESULTS

There was a significant negative correlation between increases in temperature, from 27°C to 43°C, and TGP (r = -0.641, P < 0.0005). Conversely, significant positive correlations were observed for both the elastic modulus at the gel point (r = 0.513, P = 0.0008) and df (r = 0.777, P < 0.0005) across the range of 27°C to 43°C. When temperature was reduced below 37°C, significant reductions in df and TGP occurred at ≤32°C (Bonferroni-corrected P = 0.0093) and ≤29°C (Bonferroni-corrected P = 0.0317), respectively. No significant changes were observed when temperature was increased to >37°C.

CONCLUSIONS

This study demonstrates that the gel point technique can identify alterations in clot microstructure because of changes in temperature. This was demonstrated in slower-forming clots with less structural complexity as temperature is decreased. We also found that significant changes in clot microstructure occurred when the temperature was ≤32°C.

Fluids and coagulation

PURPOSE OF REVIEW

Infusion therapy is essential in intravascular hypovolaemia and extravascular fluid deficits. Crystalloidal fluids and colloidal volume replacement affect blood coagulation when infused intravenously. The question remains if this side-effect of infusion therapy is clinically relevant in patients with and without bleeding manifestations, and if fluid-induced coagulopathy is a risk factor for anaemia, blood transfusion, and mortality, and a driver for resource use and costs.

RECENT FINDINGS

Pathomechanisms of dilutional coagulopathy and evidence for its clinical relevance in perioperative and critically ill patients are reviewed. Furthermore, the article discusses medicolegal aspects.

SUMMARY

The dose-dependent risk of dilutional coagulopathy differs between colloids (dextran > hetastarch > pentastarch > tetrastarch, gelatins > albumin). Risk awareness includes monitoring for early signs of side-effects. With rotational thromboelastometry/thrombelastography, the deterioration not only in clot strength but also in clot formation and in platelet interaction can be assessed. Fibrinogen concentrate administration may be considered in severe bleeding as well as relevant dilutional coagulopathy. Targeted doses of gelatins and tetrastarches seem to have no proven adverse effect on anaemia and allogeneic blood transfusions. Further studies are needed.

Trauma-induced coagulopathy: impact of the early coagulation support protocol on blood product consumption, mortality and costs

INTRODUCTION

Hemorrhage is the principal cause of death in the first few hours following severe injury. Coagulopathy is a frequent complication of critical bleeding. A network of Italian trauma centers recently developed a protocol to prevent and treat trauma-induced coagulopathy. A pre-post cohort multicenter study was conducted to assess the impact of the early coagulation support (ECS) protocol on blood products consumption, mortality and treatment costs.

METHODS

We prospectively collected data from all severely injured patients (Injury Severity Score (ISS) >15) admitted to two trauma centers in 2013 and compared these findings with the data for 2011. Patients transfused with at least 3 units of packed red blood cells (PRBCs) within 24 hours of an accident were included in the study. In 2011, patients with significant hemorrhaging were treated with early administration of plasma with the aim of achieving a high (≥1:2) plasma-to-PRBC ratio. In 2013, the ECS protocol was the treatment strategy. Outcome data, blood product consumption and treatment costs were compared between the two periods.

RESULTS

The two groups were well matched for demographics, injury severity (ISS: 32.9 in 2011 versus 33.6 in 2013) and clinical and laboratory data on admission. In 2013, a 40% overall reduction in PRBCs was observed, together with a 65% reduction in plasma and a 52% reduction in platelets. Patients in the ECS group received fewer blood products: 6.51 units of PRBCs versus 8.14 units. Plasma transfusions decreased from 8.98 units to 4.21 units (P <0.05), and platelets fell from 4.14 units to 2.53 units (P <0.05). Mortality in 2013 was 13.5% versus 20% in 2011 (13 versus 26 hospital deaths, respectively) (nonsignificant). When costs for blood components, factors and point-of-care tests were compared, a €76,340 saving in 2013 versus 2011 (23%) was recorded.

CONCLUSIONS

The introduction of the ECS protocol in two Italian trauma centers was associated with a marked reduction in blood product consumption, reaching statistical significance for plasma and platelets, and with a non-significant trend toward a reduction in early and 28-day mortality. The overall costs for transfusion and coagulation support (including point-of-care tests) decreased by 23% between 2011 and 2013.