Differential contributions of platelets and fibrinogen to early coagulopathy in a rat model of hemorrhagic shock

Immune dysfunction following severe trauma: A systems failure from the central nervous system to mitochondria

When a traumatic injury exceeds the body's internal tolerances, the innate immune and inflammatory systems are rapidly activated, and if not contained early, increase morbidity and mortality. Early deaths after hospital admission are mostly from central nervous system (CNS) trauma, hemorrhage and circulatory collapse (30%), and later deaths from hyperinflammation, immunosuppression, infection, sepsis, acute respiratory distress, and multiple organ failure (20%). The molecular drivers of secondary injury include damage associated molecular patterns (DAMPs), pathogen associated molecular patterns (PAMPs) and other immune-modifying agents that activate the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic stress response. Despite a number of drugs targeting specific anti-inflammatory and immune pathways showing promise in animal models, the majority have failed to translate. Reasons for failure include difficulty to replicate the heterogeneity of humans, poorly designed trials, inappropriate use of specific pathogen-free (SPF) animals, ignoring sex-specific differences, and the flawed practice of single-nodal targeting. Systems interconnectedness is a major overlooked factor. We argue that if the CNS is protected early after major trauma and control of cardiovascular function is maintained, the endothelial-glycocalyx will be protected, sufficient oxygen will be delivered, mitochondrial energetics will be maintained, inflammation will be resolved and immune dysfunction will be minimized. The current challenge is to develop new systems-based drugs that target the CNS coupling of whole-body function.

Treatment with ddAVP improves platelet-based coagulation in a rat model of traumatic hemorrhagic shock

Objectives

Trauma-induced hemorrhagic shock is characterized by increased endothelial permeability and coagulopathy. Vasopressin analog ddAVP (desmopressin) acts by reorganizing and redistributing adhesive and tight junction molecules, enhancing endothelial barrier function. Furthermore, ddAVP increases von Willebrand factor (vWF) plasma levels and thereby potentially enhances platelet-based coagulation. The objective of this study was to assess whether the use of ddAVP results in improvement of both endothelial barrier function and platelet-based coagulation, thereby improving shock reversal and reduce organ failure in a rat model of trauma and transfusion.

Methods

Blood products were prepared from syngeneic rat blood according to blood bank standards. Polytrauma was induced in Sprague Dawley rats by a fractured femur and crush injury to the intestines and liver. The rats were hemorrhaged until a mean arterial pressure of 40 mm Hg and transfused with RBCs, fresh frozen plasmas and platelets in a 1:1:1 ratio, and randomized to receive a single dose of ddAVP (n=7 per group). Blood samples were taken up to 6 hours after trauma to assess biochemistry, markers of endothelial injury and coagulation status by rotational thromboelastometry (ROTEM). Organ damage was assessed by histopathology.

Results

Rats receiving ddAVP showed significantly better shock reversal compared with controls. Also, coagulation parameters remained stable in the ddAVP treated group, whereas rats in the control group showed deterioration of coagulation parameters, including decreased clot strength and decreased platelet functioning (89% (IQR 82% to 92%) of baseline values). Platelet count and vWF antigen levels at exsanguination did not differ between groups. ddAVP did not reduce markers of endothelial dysfunction nor markers of organ injury.

Conclusions

The use of ddAVP in a rat trauma-transfusion model improved shock parameters and ROTEM parameters of clot formation. However, this did not abrogate the amount of organ failure.

Level of evidence

Level III.

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.

Arachidonic Acid-Dependent Pathway Inhibition in Platelets: its Role in Multiple Injury-Induced Coagulopathy and the Potential Mechanisms

BACKGROUND

Our previous study demonstrated the types of platelet dysfunction varied at early stage (∼3 h) in trauma-induced coagulopathy (TIC) caused by different types of injuries. And arachidonic acid (AA)-dependent pathway inhibition in platelet seemed to be specific for TIC caused by multiple injury (MI). The aim of this research was to further study AA-dependent pathway inhibition in platelets in a rat model of TIC caused by MI and to explore its potential mechanisms.

METHODS

Sprague-Dawley rat model of TIC caused by MI was established. We used thrombelastography with platelet mapping as a measure of platelet function to assess the inhibitory extent of AA-dependent activation pathway. Flow cytometry was used to determine the expression of activation-dependent granular protein P-selectin (CD62P). In addition, the plasma levels of 6-Keto-prostaglandin F1 alpha (6-Keto-PGF1α), Prostaglandin E2, and Thromboxane B2 were assessed by enzyme-linked immuno sorbent assay.

RESULTS

The inhibition rate of AA-dependent pathway after injury was significantly higher than that of control. The maximum amplitude decreased in the MI group, compared with that of control. The percentage of CD62P expression in the MI group was remarkably lower than that of control after AA treatment. The plasma concentrations of 6-Keto-PGF1α and PGE2 increased in the MI group.

CONCLUSION

Platelets inhibition was observed in TIC caused by MI at early stage after injury, which might be partially attributed to AA-dependent activation pathway dysfunction. The increase of plasma Prostacyclin and PGE2 levels may contribute to the inhibition process.

Efficacy of Different Fluid Resuscitation Methods on Coagulation Function of Rats with Traumatic Hemorrhagic Shock

BACKGROUND

Fluid resuscitation is widely used for treating traumatic hemorrhagic shock. We focused on the efficacies of different fluid resuscitation methods on improving coagulation function of traumatic hemorrhagic shock (THS) rats.

MATERIALS AND METHODS

Sprague-Dawley rats (n = 100) were randomly divided into 5 groups, namely, Sham group, THS group, acetic acid Ringer's fluid (AR) group, hydroxyethyl starch solution (HES) group, and AR + HES group. A THS rat model was established by left femoral bleeding. The effects of different fluid resuscitation methods on conventional coagulation function parameters, Rotational thromboelastometry parameters, platelet-derived microparticles and endothelial cell-derived microparticles content of the THS rats were detected by ACL TOP system, rotation thromboelastometry, and flow cytometry, respectively.

RESULTS

Using AR and HES alone had no significant effect on the coagulation function of THS rats, but the two in combination reduced the increases of thrombin time, prothrombin time, activated part thrombin time, international normalized ratio, fibrin degradation products, D-dimer and the decreases of platelet count and fibrinogen concentration induced by THS. The CT and CFT were significantly reduced, whereas α and MCF were increased in the THS rats in AR + HES group. The combination of AR and HES reversed the effect of THS on elevating platelet-derived microparticles and endothelial cell-derived microparticle levels. In addition, the coagulation was relatively the optimal in the AR, HES, and AR + HES groups when the mice were resuscitated to a mean arterial pressure of 60 mmHg.

CONCLUSIONS

AR combined with HES has a significant protective effect on coagulation function of THS rats when the mean arterial pressure reaches 60 mmHg.

Platelet consumption and hyperreactivity coexist in experimental traumatic hemorrhagic model

INTRODUCTION

Platelets are critical for hemostasis, and a low platelet count predicts mortality in trauma. The role of platelet dysfunction in severe traumatic hemorrhage and coagulopathy needs to be further defined. The aim of this study was to evaluate the platelet function in a new model of experimental traumatic hemorrhage.

MATERIAL AND METHODS

New Zealand white rabbits (n = 10) were subjected to tracheostomy and trauma laparotomy, and then bilateral femur fractures with 40% hemorrhage of their estimated blood volume. Arterial blood gases, standard coagulation tests, mean platelet volume, platelet aggregation using impedance aggregometry with agonist collagen, arachidonic acid (ASPI), and adenosine diphosphate (ADP), rotational thromboelastometry, and fibrinogen binding of platelets were analyzed using flow cytometry.

RESULTS

After traumatic hemorrhage, there was a significant physiological response with a rise in lactate (P < .001) and a decrease in base excess (P < .001) and temperature (P < .001). Platelet count decreased from a mean of 244x10⁹/L to 94 x10⁹/L (P = .004) and the mean platelet volume increased from 5.1fL to 6.1fL (P = .002). Impedance aggregometry with the agonist collagen, ASPI, and ADP was all significantly decreased after hemorrhage (P = .007). However, there was an increased fibrinogen binding of ADP-activated platelets after traumatic hemorrhage analyzed by flow cytometry (P < .05).

CONCLUSIONS

This traumatic hemorrhage model presents two parallel pathophysiological responses of platelets; platelet consumption as evidenced by a significant decrease in platelet count and aggregation, and platelet hyperreactivity as shown by a higher mean platelet volume and enhanced platelet fibrinogen binding. Further studies are needed to characterize these different aspects of platelet function in severe traumatic hemorrhage.

The use of cryopreserved platelets in a trauma-induced hemorrhage model

BACKGROUND

Cryopreserved platelet products can be stored for years and are mainly used in military settings. Following thawing, cryopreserved platelets are activated, resulting in faster clot formation but reduced aggregation in vitro, rendering their efficacy in bleeding unknown. Also, concerns remain on the safety of these products. The aim was to investigate the efficacy and safety of cryopreserved platelets in a rat model of traumatic hemorrhage.

STUDY DESIGN AND METHODS

After 1 hour of shock, rats (n = 13/group) were randomized to receive a balanced transfusion pack (1:1:1 red blood cell:plasma:platelet) made from syngeneic rat blood, containing either liquid stored platelets or cryopreserved platelets. Primary outcome was the transfusion volume required to obtain a mean arterial pressure (MAP) of 60 mmHg. Secondary outcomes were coagulation as assessed by thromboelastometry (ROTEM®) and organ failure as assessed by biochemistry and histopathology.

RESULTS

The transfusion volume to obtain a MAP of 60 mmHg was lower in animals receiving cryopreserved platelets (5.4 [4.1-7.1] mL/kg) compared to those receiving liquid stored platelets (7.5 [6.4-8.5] mL/kg, p < 0.05). ROTEM® clotting times were shorter (45 [41-48] vs. 49 [45-53]sec, p < 0.05), while maximum clot firmness was slightly lower (68 [67-68] vs. 69 [69-71]mm, p < 0.01). Organ failure was similar in both groups.

CONCLUSIONS

Use of cryopreserved platelets required less transfusion volume to reach a targeted MAP compared to liquid stored platelets, while organ injury was similar. These results provide a rationale for clinical trials with cryopreserved platelets in (traumatic) bleeding.

Study on coagulation profiles and platelet function in trauma-induced coagulopathy caused by three types of injury

BACKGROUND

Traumatic coagulopathy is a major public health issue globally with undefined mechanisms. We established rat models of hemorrhagic shock (HS), multiple injury (MI) and traumatic brain injury (TBI) to investigate the diversity of traumatic coagulopathy, especially platelet dysfunction.

METHODS

Seventy male SD rats were divided randomly into seven groups(n = 10): control, HS_30min, HS_3h, MI_30min, MI_3h, TBI_30min and TBI_3h. Plasma or whole blood was collected for conventional coagulation tests, thromboelastography and platelet mapping. X-ray, 7T magnetic resonance imaging and hematoxylin-eosin staining of injured tissues were conducted to confirm the injuries of rats model.

RESULTS

The activated partial thromboplastin time (aPTT) prolonged significantly in HS_30min and MI_3h groups, compared with those in control (P = 0.0403 and P = 0.0076, respectively). R values decreased in HS_30min and HS_3h groups, compared with those in control (P < 0.0001 and P < 0.0001, respectively). The maximum amplitude (MA) were 71.8 ± 0.6 mm, 71.9 ± 0.5 mm, 71.8 ± 0.7 mm, 70.0 ± 0.7 mm, 72.6 ± 0.9 mm, 70.4 ± 0.9 mm in HS_30min, HS_3h, MI_30min, MI_3h, TBI_30min and TBI_3h groups respectively, which were lower than those in control (P = 0.0304, P = 0.0205, P = 0.0431, P = 0.0007 and P = 0.0066, respectively). The platelet counts were 539±46 × 10⁹/L, 523±31 × 10⁹/L, 629 ± 18 × 10⁹/L and 636±20 × 10⁹/L in HS_30min, HS_3h, MI_3h and TBI_3h groups respectively, which were lower than those in control (P = 0.0040, P = 0.0001, P = 0.0127 and P = 0.0232, respectively). The adenosine diphosphate (ADP) inhibition rate decreased in HS_30min group, compared with that in control (P = 0.0355). While, ADP inhibition rate increased in HS_3h and TBI_3h groups (P = 0.0041 and P = 0.0433 vs. control, respectively). The arachidonic acid (AA) inhibition rate increased in MI_30min and MI_3h groups, compared with control (P = 0.0029 and P = 0.0185, respectively).

CONCLUSION

These results demonstrated that it might be the failure of forming a strong clot instead of the prolonged clot time, which contributed to traumatic coagulopathy. The platelet dysfunctions might contribute to trauma-induced coagulopathy in different ways. The loss of platelets might be the main reason for HS-induced coagulopathy. While, AA-dependent pathway inhibition might account for MI-induced coagulopathy. ADP-dependent pathway inhibition might be the major contributor for TBI-induced coagulopathy.

Thromboelastography Detects Possible Coagulation Disturbance in Pediatric Patients with Portal Cavernoma

Background

Thromboelastography (TEG) allows a dynamic assessment of clot formation and dissolution that might be useful for assessing the relative contribution of the coagulation components to overall clot formation and dissolution, but it has not been fully defined in patients with portal cavernoma (PC).

Methods

We retrospectively recruited consecutive patients with PC between July 2006 and June 2016 who had no abdominal malignancy or liver cirrhosis. Blood samples were drawn on admission and were subjected to coagulation parameter assessment, including conventional coagulation tests, measurement of the circulating levels of procoagulant and anticoagulant factors, and TEG assessment.

Results

Compared with controls, patients with PC showed significant reductions in the serum levels of procoagulant factors and anticoagulants factors, whereas factor VIII was slightly elevated. TEG showed clot formation (α-angle), and the maximal clot strength (MA) was higher in patients with PC than in controls, indicating a hypercoagulable state. Thrombocytopenia decreased both clot formation (α-angle) and the maximal clot strength (MA) but was still significantly higher than the control. Furthermore, patients with PC had a higher level of D-dimer and LY30 than did controls, indicating the in vivo activation of coagulation and fibrinolysis.

Conclusion

TEG analysis showed that patients with PC were in a hypercoagulable state that could be partially masked by thrombocytopenia secondary to splenomegaly and hypersplenism in these patients, which indicates that our current prophylaxis and therapy regimen could be improved.

Modeling trauma in rats: similarities to humans and potential pitfalls to consider

Trauma is the leading cause of mortality in humans below the age of 40. Patients injured by accidents frequently suffer severe multiple trauma, which is life-threatening and leads to death in many cases. In multiply injured patients, thoracic trauma constitutes the third most common cause of mortality after abdominal injury and head trauma. Furthermore, 40-50% of all trauma-related deaths within the first 48 h after hospital admission result from uncontrolled hemorrhage. Physical trauma and hemorrhage are frequently associated with complex pathophysiological and immunological responses. To develop a greater understanding of the mechanisms of single and/or multiple trauma, reliable and reproducible animal models, fulfilling the ethical 3 R's criteria (Replacement, Reduction and Refinement), established by Russell and Burch in 'The Principles of Human Experimental Technique' (published 1959), are required. These should reflect both the complex pathophysiological and the immunological alterations induced by trauma, with the objective to translate the findings to the human situation, providing new clinical treatment approaches for patients affected by severe trauma. Small animal models are the most frequently used in trauma research. Rattus norvegicus was the first mammalian species domesticated for scientific research, dating back to 1830. To date, there exist numerous well-established procedures to mimic different forms of injury patterns in rats, animals that are uncomplicated in handling and housing. Nevertheless, there are some physiological and genetic differences between humans and rats, which should be carefully considered when rats are chosen as a model organism. The aim of this review is to illustrate the advantages as well as the disadvantages of rat models, which should be considered in trauma research when selecting an appropriate in vivo model. Being the most common and important models in trauma research, this review focuses on hemorrhagic shock, blunt chest trauma, bone fracture, skin and soft-tissue trauma, burns, traumatic brain injury and polytrauma.

Use of a high platelet-to-RBC ratio of 2:1 is more effective in correcting trauma-induced coagulopathy than a ratio of 1:1 in a rat multiple trauma transfusion model

BACKGROUND

Platelet dysfunction importantly contributes to trauma-induced coagulopathy (TIC). Our aim was to examine the impact of transfusing platelets (PLTs) in a 2:1 PLT-to-red blood cell (RBC) ratio versus the standard 1:1 ratio on transfusion requirements, correction of TIC, and organ damage in a rat multiple trauma transfusion model.

METHODS

Mechanically ventilated male Sprague Dawley rats were traumatized by crush injury to the small intestine and liver and a fracture of the femur, followed by exsanguination until a mean arterial pressure (MAP) of 40 mmHg. Animals were randomly assigned to receive resuscitation in a high PLT dose (PLT to plasma to RBC in a ratio of 2:1:1) or a standard PLT dose (ratio of 1:1:1) until a MAP of 60 mmHg was reached (n = 8 per group). Blood samples were taken for biochemical and thromboelastometry (ROTEM) assessment. Organs were harvested for histopathology.Outcome measures were transfusion requirements needed to reach a pretargeted MAP, as well as ROTEM correction and organ failure.

RESULTS

Trauma resulted in coagulopathy as assessed by deranged ROTEM results. Mortality rate was 19%, with all deaths occurring in the standard dose group. The severity of hypovolemic shock as assessed by lactate and base excess was not different in both groups. The volume of transfusion needed to reach the MAP target was lower in the high PLT dose group compared to the standard dose, albeit not statistically significant (p = 0.054). Transfusion with a high PLT dose resulted in significant stronger clot firmness compared to the standard dose at all time points following trauma, while platelet counts were similar. Organ failure as assessed by biochemical analysis and histopathology was not different between groups, nor were there any thromboembolic events recorded.

CONCLUSIONS

Resuscitation with a high (2:1) PLT-to-RBC ratio was more effective compared to standard (1:1) PLT-to-RBC ratio in treating TIC, with a trend towards reduced transfusion volumes. Also, high PLT dose did not aggravate organ damage. Transfusion strategies using higher PLT dose regiments might be a feasible treatment option in hemorrhaging trauma patients for the correction of TIC.

Conventional and Specific-Pathogen Free Rats Respond Differently to Anesthesia and Surgical Trauma

Specific-pathogen free (SPF) animals were introduced in the 1960s to minimize disease and infection as variables in biomedical research. Our aim was to examine differences in physiological response in rat colonies bred and housed in a conventional versus SPF facility, and implications for research. Sprague-Dawley rats were anesthetized and catheterized for blood and pressure monitoring, and electrocardiogram (ECG) leads implanted. Hematology was assessed, and coagulation profile using rotational thromboelastometry. Health screening was outsourced to Cerberus Sciences. SPF rats had significantly lower pulse pressure (38% decrease), arrhythmias and prolonged QTc (27% increase) compared to conventional rats. No arrhythmias were found in conventional rats. SPF rats had significantly higher white cell, monocyte, neutrophil and lymphocyte counts, and were hyperfibrinolytic, indicated by EXTEM maximum lysis >15%. Independent assessment revealed similar pathogen exclusion between colonies, with the exception of Proteus in SPF animals. Returning to a conventional facility restored normal host physiology. We conclude that SPF animals displayed an abnormal hemodynamic, hematological and hemostatic phenotype in response to anesthesia and surgery, and provide a number of recommendations to help standardize research outcomes and translation.

High-dose Factor XIII administration induces effective hemostasis for trauma-associated coagulopathy (TAC) both in vitro and in rat hemorrhagic shock in vivo models

BACKGROUND

Trauma-associated coagulopathy (TAC) is an early and primary complication in severe trauma patients. Factor XIII (FXIII) is reported to stabilize a clot in the late phase of the coagulation cascade. The goal of this study was to investigate whether the administration of FXIII improves the condition of TAC both in vitro and in vivo.

METHODS

We evaluated the effects of different doses, including a very high dose of FXIII (3.6-32.4 IU/mL) on tissue-plasminogen activator-induced hyperfibrinolysis and the combined condition of dilutional coagulopathy and tissue-plasminogen activator-induced hyperfibrinolysis in vitro. The coagulation status was analyzed by rotational thromboelastometry (ROTEM) and Sonoclot. Then, we evaluated the effect of high-dose FXIII (300 IU/kg) for severe coagulopathy in vivo using a rat liver trauma model in which coagulopathy similar to TAC was observed. Survival time and the amount of intra-abdominal bleeding of rats were measured, and a coagulation test was also performed. Histologic evaluations of rats' lung and kidney after FXIII administration were completed.

RESULTS

High-dose FXIII significantly improved clot strength as well as increased resistance to hyperfibrinolysis in vitro which was confirmed by ROTEM. Platelet function on Sonoclot was significantly increased by FXIII in a dose-dependent manner. Factor XIII significantly decreased the total amount of bleeding and prolonged the survival time compared to control (control vs FXIII: 108.9 ± 11.4 vs 32.6 ± 5.5 mL/kg; p < 0.001; 26.0 ± 8.8 vs 120 minutes, p < 0.001) in a rat model. Rotational thromboelastometry parameters and platelet function on Sonoclot were significantly improved in the FXIII (+) group compared to control. No adverse effects of FXIII were detected histologically.

CONCLUSION

Factor XIII not only generated stable clot resistance to hyperfibrinolysis but also enhanced platelet function by facilitating clot retraction. High-dose FXIII administration therapy has significant clinical impact for severe trauma accompanied with TAC.

STUDY TYPE

Human in vitro and rat in vivo experimental study.

Buprenorphine Analgesia Leads to Coagulopathy and Increased Plasma Fibrinogen in Healthy Rats: Implications For Small Animal Research

INTRODUCTION

Buprenorphine is the recommended analgesic for post-surgical pain and associated stress in small animal research. Our aim was to examine the effect of isoflurane anesthesia and buprenorphine analgesia on blood coagulation in the rat using rotational thromboelastometry.

METHODS

Adult male Sprague Dawley rats were randomly assigned to one of four groups (n = 6): baseline (Thiobarb anesthesia), 5% isoflurane anesthesia, isoflurane-buprenorphine (0.05-mg/kg s.c.), and buprenorphine alone. After 1 h, animals were anesthetized and blood was sampled.

RESULTS

We report that isoflurane or buprenorphine had little or no effects on clotting times, clot formation, or clot lysis in EXTEM or INTEM. However, buprenorphine significantly increased FIBTEM alpha-angle, clot formation rates, and maximum clot formation velocities. Buprenorphine also increased EXTEM, FIBTEM, and INTEM A10 (clot strength), maximum clot firmness (clot quality), and maximum clot elasticity ( (clot elasticity). The combination of isoflurane and buprenorphine significantly increased clot amplitude but not to the same extent. The fibrinogen contribution to clot strength was 1.9-fold higher than baseline in the buprenorphine group, and 1.4-fold higher in the isoflurane-buprenorphine group. Plasma fibrinogen levels were 2.5-fold higher in both groups compared with the baseline value or isoflurane group (6.1 g/L vs. 2.4 g/L, P < 0.05).

CONCLUSIONS

We conclude buprenorphine analgesia significantly increased clot strength without affecting fibrinolysis, and increased plasma fibrinogen, implying that the drug increased liver fibrinogen synthesis and release. Possible implications for small animal research are discussed.

7.5% NaCl Resuscitation Leads to Abnormal Clot Fibrinolysis after Severe Hemorrhagic Shock and its Correction with 7.5% NaCl Adenosine, Lidocaine, and Mg2

Background

Hyperfibrinolysis is a common complication of hemorrhagic shock. Our aim was to examine the effect of small-volume 7.5% NaCl adenosine, lidocaine, and Mg²⁺ (ALM) on fibrinolysis in the rat model of hemorrhagic shock.

Methods

Rats were anesthetized and randomly assigned to one of four groups: (1) baseline, (2) shock, (3) 7.5% NaCl controls, and (4) 7.5% NaCl ALM. Animals were bled for 20 min (42% blood loss) and left in shock for 60 min before resuscitation with 0.3 ml intravenous bolus 7.5% NaCl ± ALM. Rats were sacrificed at 5, 10, 15, 30, and 60 min for rotation thromboelastometry and 15 and 60 min for ELISA analyses.

Results

After hemorrhagic shock, 7.5% NaCl failed to resuscitate and exacerbated coagulopathy and fibrinolysis. At 15 and 60 min, the activation as extrinsically-activated test using tissue factor (EXTEM) with aprotinin to inhibit fibrinolysis (APTEM) test showed little or no correction of fibrinolysis, indicating a plasmin-independent fibrinolysis. Clots also had ~ 60% lower fibrinogen (fibrin-based EXTEM activated test with platelet inhibitor cytochalasin D A10) and 36%-50% reduced fibrinogen-to-platelet ratio (11%-14% vs. 22% baseline). In contrast, 7.5% NaCl ALM resuscitated mean arterial pressure and attenuated hyperfibrinolysis and coagulopathy by 15 min. Correction was associated with lower plasma tissue factor, higher plasminogen activator inhibitor-1, and lower D-dimers (5% of controls at 60 min). Platelet selectin fell to undetectable levels in ALM animals, which may imply improved endothelial and platelet function during resuscitation.

Conclusions

Small-volume 7.5% NaCl resuscitation exacerbated coagulopathy and fibrinolysis that was not corrected by APTEM test. Fibrinolysis appears to be associated with altered fibrin structure during early clot formation and elongation. In contrast, 7.5% NaCl ALM rapidly corrected both coagulopathy and hyperfibrinolysis.

Adenosine, lidocaine and Mg2+ (ALM) fluid therapy attenuates systemic inflammation, platelet dysfunction and coagulopathy after non-compressible truncal hemorrhage

Background

Systemic inflammation and coagulopathy are major drivers of injury progression following hemorrhagic trauma. Our aim was to examine the effect of small-volume 3% NaCl adenosine, lidocaine and Mg²⁺ (ALM) bolus and 0.9% NaCl/ALM ‘drip’ on inflammation and coagulation in a rat model of hemorrhagic shock.

Methods

Sprague-Dawley rats (429±4 g) were randomly assigned to: 1) shams, 2) no-treatment, 3) saline-controls, 4) ALM-therapy, and 5) Hextend^®. Hemorrhage was induced in anesthetized-ventilated animals by liver resection (60% left lateral lobe and 50% medial lobe). After 15 min, a bolus of 3% NaCl ± ALM (0.7 ml/kg) was administered intravenously (Phase 1) followed 60 min later by 4 hour infusion of 0.9% NaCl ± ALM (0.5 ml/kg/hour) with 1-hour monitoring (Phase 2). Plasma cytokines were measured on Magpix^® and coagulation using Stago/Rotational Thromboelastometry.

Results

After Phase 1, saline-controls, no-treatment and Hextend^® groups showed significant falls in white and red cells, hemoglobin and hematocrit (up to 30%), whereas ALM animals had similar values to shams (9–15% losses). After Phase 2, these deficits in non-ALM groups were accompanied by profound systemic inflammation. In contrast, after Phase 1 ALM-treated animals had undetectable plasma levels of IL-1α and IL-1β, and IL-2, IL-6 and TNF-α were below baseline, and after Phase 2 they were less or similar to shams. Non-ALM groups (except shams) also lost their ability to aggregate platelets, had lower plasma fibrinogen levels, and were hypocoagulable. ALM-treated animals had 50-fold higher ADP-induced platelet aggregation, and 9.3-times higher collagen-induced aggregation compared to saline-controls, and had little or no coagulopathy with significantly higher fibrinogen shifting towards baseline. Hextend^® had poor outcomes.

Conclusions

Small-volume ALM bolus/drip mounted a frontline defense against non-compressible traumatic hemorrhage by defending immune cell numbers, suppressing systemic inflammation, improving platelet aggregation and correcting coagulopathy. Saline-controls were equivalent to no-treatment. Possible mechanisms of ALM's immune-bolstering effect are discussed.

Immune-inflammatory activation after a single laparotomy in a rat model: effect of adenosine, lidocaine and Mg2+ infusion to dampen the stress response

Our aim was to examine the effect of low-volume 0.9% NaCl adenosine, lidocaine and Mg2+ (ALM) ‘drip’ on early immune-inflammatory activation after a single laparotomy with no further manipulation. Male Sprague–Dawley rats were anesthetized and randomly assigned to one of the groups, baseline, 1 h infusion 0.9% NaCl ± ALM and metrics, 1 h infusion and 6-h metrics, and 6 h continuous infusion and metrics. Complete blood count, acid–base balance, systemic levels of IL-6 and IL-10, and coagulation status were measured. After 1 h, there was a disproportionate increase in circulating neutrophils between saline and ALM groups despite an identical 45% fall in lymphocytes. Disproportionate increases also occurred in platelet counts 1 h after surgery, and saline controls had increased respiratory alkalosis at 6 h with higher lactate. Systemic inflammation was also evident after 1 h in both groups (plasma IL-6 increase) and was amplified in saline-controls after 6 h. The ALM group increased anti-inflammatory cytokine IL-10. Surgery was not associated with acute coagulopathy; however, there were significant reductions in fibrinolysis. Following a single laparotomy, ALM infusion appeared to reduce stress-induced release of neutrophils and platelets into the circulation, and reduced acid–base disturbance. After 1 h, both groups had similar IL-6 levels, but ALM animals had increased IL-10, indicating improved inflammatory balance. The uncoupling of inflammation and coagulation activation but not fibrinolysis may offer a unique opportunity to investigate differential activation of innate immunity in response to sterile injury in this model.

Nonhuman primate model of polytraumatic hemorrhagic shock recapitulates early platelet dysfunction observed following severe injury in humans

BACKGROUND

Platelet dysfunction has been described as an early component of trauma-induced coagulopathy. The platelet component of trauma-induced coagulopathy remains to be fully elucidated and translatable animal models are required to facilitate mechanistic investigations. We sought to determine if the early platelet dysfunction described in trauma patients could be recapitulated in a nonhuman primate model of polytraumatic hemorrhagic shock.

METHODS

Twenty-four male rhesus macaques weighting 7 to 14 kg were subjected to 60 minutes (min) of severe pressure-targeted controlled hemorrhagic shock (HS) with and without other injuries. After 60 min, resuscitation with 0.9% NaCl and whole blood was initiated. Platelet counts and platelet aggregation assays were performed at baseline (BSLN), end of shock (EOS; T = 60 min), end of resuscitation (EOR; T = 180 min), and T = 360 min on overall cohort. Results are reported as mean ± standard deviation (SD) or median (interquartile range). Statistical analysis was conducted using Spearmen correlation, one-way analysis of variance, two-way repeated-measures analysis of variance, paired t-test or Wilcoxon nonparametric test, with p < 0.05 considered significant.

RESULTS

Platelet count in all injury cohorts decreased over time, but no animals developed thrombocytopenia. Correlations were observed between platelet aggregation and platelet count for all agonists: adenosine diphosphate, thrombin recognition-activating peptide-6, collagen, and arachidonic acid. Overall, compared to BSLN, platelet aggregation decreased for all agonist at EOS, EOR, and T = 360 min. When normalized to platelet count, platelet aggregation in response to agonist thrombin recognition-activating peptide-6 demonstrated no change from BSLN at subsequent time points. Aggregation to adenosine diphosphate was significantly less at EOR but not EOS or T = 360 min compared to BSLN. Platelet aggregation to collagen and arachidonic acid was not significantly different at EOS compared to BSLN but was significantly less at EOR and T = 360 min.

CONCLUSION

Nonhuman primates manifest early platelet dysfunction in response to polytraumatic hemorrhagic shock, consistent with that reported in severely injured human patients. Nonhuman primate models potentially are translationally valuable for understanding the mechanisms and pathophysiology of trauma-induced platelet dysfunction.