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

Comparison of two viscoelastic testing devices in a porcine model of surgery, hemorrhage and resuscitation

Introduction

Viscoelastic hemostatic assays (VHA) are integral in contemporary hemostatic resuscitation, offering insights into clot formation, firmness, and lysis for rapid diagnosis and targeted therapy. Large animal models, particularly swine, provide anatomical and physiological analogies for coagulation research. Despite the growing use of VHAs, the ClotPro® device's applicability in porcine models remains unexplored. This study investigates ClotPro® in a porcine model of abdominal surgery, severe hemorrhage, and resuscitation, comparing it with the established ROTEM® delta system.

Methods

Twenty-seven healthy pigs underwent abdominal surgery, hemorrhage and resuscitation. ClotPro® and ROTEM® were used to assess viscoelastic hemostatic properties at baseline, after surgery, 60 min after shock induction, 60 and 120 min after resuscitation.

Results

Clotting times in extrinsically and intrinsically stimulated assays exhibited fair to moderate correlation. Clot firmness in extrinsically stimulated tests could be used interchangeably while fibrin polymerization assays revealed significant differences between the devices. Fibrin polymerization assays in ClotPro® consistently yielded higher values than ROTEM®. Furthermore, the study evaluated the ClotPro® TPA-test's applicability in porcine blood, revealing failure of lysis induction in porcine blood samples.

Conclusion

This research contributes valuable insights into the use of ClotPro® in porcine models of hemorrhage and coagulopathy, highlighting both its applicability and limitations in comparison to ROTEM® delta. The observed differences, especially in fibrin polymerization assays, emphasize the importance of understanding device-specific characteristics when interpreting results. Due to its inapplicability, TPA-test should not be used in porcine blood to evaluate fibrinolytic potential. The study provides a foundation for future investigations into the use of different viscoelastic hemostatic assays in porcine animal models.

Empirical and modified hemostatic resuscitation for liver blast injury combined with seawater immersion: A preliminary study

PURPOSE

To compare the effects of empirical and modified hemostatic resuscitation for liver blast injury combined with seawater immersion.

METHODS

Thirty rabbits were subjected to liver blast injury combined with seawater immersion, and were then divided into 3 groups randomly (n = 10 each): group A (no treatment after immersion), group B (empirical resuscitation with 20 mL hydroxyethyl starch, 50 mg tranexamic acid, 25 IU prothrombin complex concentrate and 50 mg/kg body weight fibrinogen concentrate), and group C (modified resuscitation with additional 10 IU prothrombin complex concentrate and 20 mg/kg body weight fibrinogen concentrate based on group B). Blood samples were gathered at specified moments for assessment of thromboelastography, routine coagulation test, and biochemistry. Mean arterial pressure, heart rate, and survival rate were also documented at each time point. The Kolmogorov-Smirnov test was used to examine the normality of data distribution. Multigroup comparisons were conducted with one-way ANOVA.

RESULTS

Liver blast injury combined with seawater immersion resulted in severe coagulo-fibrinolytic derangement as indicated by prolonged prothrombin time (s) (11.53 ± 0.98 vs. 7.61 ± 0.28, p＜0.001), activated partial thromboplastin time (APTT) (s) (33.48 ± 6.66 vs. 18.23 ± 0.89, p＜0.001), reaction time (R) (min) (5.85 ± 0.96 vs. 2.47 ± 0.53, p＜0.001), decreased maximum amplitude (MA) (mm) (53.20 ± 5.99 vs. 74.92 ± 5.76, p＜0.001) and fibrinogen concentration (g/L) (1.188 ± 0.29 vs. 1.890 ± 0.32, p = 0.003), and increased D-dimer concentration (mg/L) (0.379 ± 0.32 vs. 0.051 ± 0.03, p = 0.005). Both empirical and modified hemostatic resuscitation could improve the coagulo-fibrinolytic states and organ function, as indicated by shortened APTT and R values, decreased D-dimer concentration, increased fibrinogen concentration and MA values, lower concentration of blood urea nitrogen and creatine kinase-MB in group B and group C rabbits in comparison to that observed in group A. Further analysis found that the R values (min) (4.67 ± 0.84 vs. 3.66 ± 0.98, p = 0.038), APTT (s) (23.16 ± 2.75 vs. 18.94 ± 1.05, p = 0.001), MA (mm) (60.10 ± 4.74 vs. 70.21 ± 3.01, p < 0.001), and fibrinogen concentration (g/L) (1.675 ± 0.21 vs. 1.937 ± 0.16, p = 0.013) were remarkably improved in group C than in group B at 2 h and 4 h after injury. In addition, the concentration of blood urea nitrogen (mmol/L) (24.11 ± 1.96 vs. 21.00 ± 3.78, p = 0.047) and creatine kinase-MB (U/L) (85.50 ± 13.60 vs. 69.74 ± 8.56, p = 0.013) were lower in group C than in group B at 6 h after injury. The survival rates in group B and group C were significantly higher than those in group A at 4 h and 6 h after injury (p < 0.001), however, there were no statistical differences in survival rates between group B and group C at each time point.

CONCLUSIONS

Modified hemostatic resuscitation could improve the coagulation parameters and organ function better than empirical hemostatic resuscitation.

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

Correlation between Coagulation Fibrinolysis Function and Outcomes during Hospitalization in Patients with Severe Traumatic Hemorrhagic Shock

Objective

To analyze the correlation between coagulation fibrinolysis function and outcomes during hospitalization in patients with severe traumatic hemorrhagic shock.

Methods

A retrospective collection was performed on the clinical data of 106 patients with severe traumatic shock admitted to the hospital between January 2020 and January 2022. According to the injury severity score (ISS), they were divided into the S1 group (ISS <25 points, n = 70) and the S2 group (ISS ≥25 points, n = 36). The prothrombin time (PT), fibrinogen (Fib), thrombin time (TT), and activated partial thromboplastin time (APTT) were detected by the coagulation assay. The aD-dimer (D-D) was detected by an enzyme-linked immunosorbent assay. Antithrombin activity (AT : A) and plasminogen activity (PLG : A) were detected by the chromogenic substrate method. The relationship between coagulation fibrinolysis indexes and injury severity was analyzed by Spearman's correlation analysis. The predictive value of coagulation fibrinolysis indexes for outcomes of patients with severe traumatic hemorrhagic shock was evaluated by receiver operating characteristic (ROC) curves.

Results

The levels of PT, APTT, D-D, TT, AT : A and PLG : A in the S2 group were higher than those in S1 group, while the Fib level was lower than that in the S1 group (P < 0.05). A Spearman's analysis showed that PT, APTT, TT, D-D, AT : A, and PLG : A were positively correlated with injury severity (P < 0.05), while Fib was negatively correlated with it (P < 0.05). Among the 106 patients, there were 89 survived cases and 17 died cases. The levels of PT, APTT, D-D, AT : A and PLG : A in the death group were lower than those in the survival group, while the Fib level was higher than that in the survival group. The results of ROC curve analysis showed that serum PT, APTT, Fib, TT and D-D were of predictive value for outcomes (AUC = 0.713, AUC = 0.683, AUC = 0.712, AUC = 0.761, AUC = 0.730, AUC = 0.765, AUC = 0.673, P < 0.05), and cutoff values were 20.29 s, 34.79 s, 3.54 g/L, 20.97 s, 1.42 μg/L, 73.53% and 63.97%, respectively.

Conclusion

There is coagulation and fibrinolysis dysfunction in patients with severe traumatic hemorrhagic shock, which is related to injury severity. The coagulation fibrinolysis indexes have a certain predictive value for outcomes of patients.

Effectiveness of Tranexamic Acid in Reducing Hemorrhage in Isolated Blunt Solid Organ Injury

Introduction: There is considerable interest in the use of tranexamic acid (TXA) for the control of hemorrhages in trauma patients. Multiple recent studies found that TXA used in the setting of a suspected significant hemorrhage in trauma patients significantly reduced mortality. To date, there are no cited studies that specifically address hemorrhage due to solid organ injury (i.e., kidneys, liver, and spleen) and TXA use in humans. Our current research addresses whether TXA is effective in reducing complications and mortality from traumatic hemorrhage in the setting of a specific solid organ injury.

Methods: We conducted a retrospective observational cohort study utilizing propensity score matching at Arrowhead Regional Medical Center (ARMC) from February 1, 2009 to February 1, 2019. This study period marks five years prior to and five years after February 1, 2004, which is the date when TXA first started to be used at ARMC in the management of traumatic hemorrhage. We compared for statistical difference between corresponding injury types in the TXA and non-TXA groups.

Results: Before the propensity matching, there were 123 patients who received TXA and 118 patients who did not. After propensity match for age and injury severity score (ISS), 35 patients were included in each group. We found no statistically significant difference between TXA and non-TXA treatment groups in terms of mortality at 24 hours (p-value=0.4945), mortality at 48 hours (p-value=0.4945), and mortality at 28 days (p-value=0.7426). We found no statistically significant difference between the need for interventional radiology intervention at 72 hours (p-value=0.3932), surgical intervention at 72 hours (p-value=0.2123) and possible TXA related complications (p-value=1).

Conclusion: Although prior studies showed that TXA use in the setting of trauma may be beneficial, the specific candidate-selection criteria remain unclear. The results of our study suggest that the benefit from TXA in the setting of the isolated splenic, liver, and or renal injury may be negligible. We believe that this first-of-its-kind study adds to the growing body of knowledge about the utility of TXA and helps guide patient-selection criteria.

Getting to the Core of It All: Nanocapsules to Mitigate Infusion Reactions Can Promote Hemostasis and Be a Platform for Intravenous Therapies

One of the significant challenges to translation of intravenously administered nanomaterials has been complement-mediated infusion reactions which can be lethal. Slow infusions can reduce infusion reactions, but slow infusions are not always possible in applications like controlling bleeding following trauma. Thus, avoiding complement activation and infusion responses is essential to manage bleeding. We identified nanocapsules based on polyurethane as candidates that did not activate C5a and explored their PEGylation and functionalization with the GRGDS peptide to create a new class of hemostatic nanomaterials. Using the clinically relevant rotational thromboelastography (ROTEM), we determined that nanocapsules promote faster clotting than controls and maintain the maximum clot firmness, which is critical for reducing bleeding. Excitingly, these polyurethane-based nanocapsules did not activate complement or the major pro-inflammatory cytokines. This work provides critical evidence for the role of modulating the core material in developing safer nanomedicines for intravenous applications.

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.

Nanostructured fibrin agarose hydrogel as a novel haemostatic agent

Blood loss remains a major concern during surgery and can increase the morbidity of the intervention. The use of topical haemostatic agents to overcome this issue therefore becomes necessary. Fibrin sealants are promising haemostatic agents due to their capacity to promote coagulation, but their effectiveness and applicability need to be improved. We have compared the haemostatic efficacy of a novel nanostructured fibrin‐agarose hydrogel patch, with (c‐NFAH) or without cells (a‐NFAH), against two commercially available haemostatic agents in a rat model of hepatic resection. Hepatic resections were performed by making short or long incisions (mild or severe model, respectively), and haemostatic agents were applied to evaluate time to haemostasis, presence of haematoma, post‐operative adhesions to adjacent tissues, and inflammation factors. We found a significantly higher haemostatic success rate (time to haemostasis) with a‐NFAH than with other commercial haemostatic agents. Furthermore, other relevant outcomes investigated were also improved in the a‐NFAH group, including no presence of haematoma, lower adhesions, and lower grades of haemorrhage, inflammation, and necrosis in histological analysis. Overall, these findings identify a‐NFAH as a promising haemostatic agent in liver resection and likely in a range of surgical procedures.

Tranexamic acid-loaded starch hemostatic microspheres

Efficacious hemostatics have significant potential for use in rapid exsanguinating hemorrhage control by emergency medical technicians or military medics nowadays. Current hemostatics focus primarily on speeding up the formation of blood clots, but inhibiting fibrinolysis is also critical for promoting coagulation and improving survival rates. Here we report a drug-loaded cross-linked microporous starch (TACMS) fabricated by loading tranexamic acid (TA) with antifibrinolytic properties into cross-linked microporous starch (CMS). The results showed that the cross-linking modification improved the mechanical properties and the particle density. The introduction of TA had no influence on water absorption of CMS. TACMS retained good physical hemostatic capacity and excellent biocompatibility. The prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) of TACMS with 20 mg g⁻¹ of TA were shortened greatly, indicating the chemical hemostasis of TACMS. TACMS demonstrated a 70% reduction in clotting time in vitro compared to CMS, which effectively inhibited the dissolution of fibrin and increased the strength of blood clots. Importantly, TACMS presented excellent hemostatic performance in rabbit ear artery injury and rabbit liver injury and even better hemostatic ability than Arista®. In conclusion, cross-linking, enzyme hydrolysis and modification of starch greatly improved absorption speed, blood uptake capacity and mechanical strength, and the introduction of TA simultaneously amplified the physical hemostasis and inhibited the dissolution of fibrin. The potent hemostatic ability of TACMS resulted from the synergistic role of physical hemostasis and drug hemostasis. The results of the present study put forward TACMS as a safe and effective hemostatic system and present a platform for further optimization studies of materials with enhanced hemostatic capabilities for specific injury types.

Efficacious hemostatics have significant potential for use in rapid exsanguinating hemorrhage control by emergency medical technicians or military medics nowadays.

Segmental innervation of the Göttingen minipig hind body. An electrophysiological study

The Göttingen minipig is being used increasingly in biomedical research. The anatomical structure of the porcine peripheral nervous system has been extensively characterized, but no equivalent to the dermatome map, which is so valuable in human neurophysiological research, has been created. We characterized the medullar segmental skin and muscle innervations of the minipig hind body, using neurophysiological methodology. Six adult minipigs underwent unilateral laminectomy from L2 to S3, exposing the nerve roots. The skin of the hind part of the body was divided into 36 predefined fields, based on anatomical landmarks for consistent reproducibility. We recorded the evoked potential in each exposed nerve root L2-S3 for cutaneous stimulation of each skin field, mapping the sensory innervation of the entire hind body. We subsequently recorded the motor response in seven predefined muscles during sequential stimulation of the L2-S3 nerve roots. We obtained a clear sensory evoked potential in the nerve roots during stimulation of the skin fields, allowing us to map the sensory innervation of the minipig hind body. Neurophysiological data from skin stimulation and muscle recordings enabled us to map the sensory innervation of the Göttingen minipig hind body and provide information about muscular innervation. The skin fields were sensory innervated by more than one root. The muscles each had one dominant root with minor contribution from neighboring roots. This is consistent with experimental data from human studies.