Fresh frozen plasma resuscitation attenuates platelet dysfunction compared with normal saline in a large animal model of multisystem trauma

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.

Volume Resuscitation in the Acutely Hemorrhaging Patient: Historic Use to Current Applications

Acute hemorrhage in small animals results from traumatic and non-traumatic causes. This review seeks to describe current understanding of the resuscitation of the acutely hemorrhaging small animal (dog and cat) veterinary patient through evaluation of pre-clinical canine models of hemorrhage and resuscitation, clinical research in dogs and cats, and selected extrapolation from human medicine. The physiologic dose and response to whole blood loss in the canine patient is repeatable both in anesthetized and awake animals and is primarily characterized clinically by increased heart rate, decreased systolic blood pressure, and increased shock index and biochemically by increased lactate and lower base excess. Previously, initial resuscitation in these patients included immediate volume support with crystalloid and/or colloid, regardless of total volume, with a target to replace lost vascular volume and bring blood pressure back to normal. Newer research now supports prioritizing hemorrhage control in conjunction with judicious crystalloid administration followed by early consideration for administration of platelets, plasma and red blood during the resuscitation phase. This approach minimizes blood loss, ameliorates coagulopathy, restores oxygen delivery and correct changes in the glycocalyx. There are many hurdles in the application of this approach in clinical veterinary medicine including the speed with which the bleeding source is controlled and the rapid availability of blood component therapy. Recommendations regarding the clinical approach to volume resuscitation in the acutely hemorrhaging veterinary patient are made based on the canine pre-clinical, veterinary clinical and human literature reviewed.

Clinical predictors of prognosis in patients with traumatic brain injury combined with extracranial trauma

Objective: The purpose of this study was to investigate whether routine blood tests on admission and clinical characteristics can predict prognosis in patients with traumatic brain injury (TBI) combined with extracranial trauma. Methods: Clinical data of 182 patients with TBI combined with extracranial trauma from April 2018 to December 2019 were retrospectively collected and analyzed. Based on GOSE score one month after discharge, the patients were divided into a favorable group (GOSE 1-4) and unfavorable group (GOSE 5-8). Routine blood tests on admission and clinical characteristics were recorded. Results: Overall, there were 48 (26.4%) patients with unfavorable outcome and 134 (73.6%) patients with favorable outcome. Based on multivariate analysis, independent risk factors associated with unfavorable outcome were age (odds ratio [OR], 1.070; 95% confidence interval [CI], 1.018-1.124; p<0.01), admission Glasgow Coma Scale (GCS) score (OR, 0.807; 95% CI, 0.675-0.965; p<0.05), heart rate (OR, 1.035; 95% CI, 1.004-1.067; p<0.05), platelets count (OR, 0.982; 95% CI, 0.967-0.997; p<0.05), and tracheotomy (OR, 15.201; 95% CI, 4.121-56.078; p<0.001). Areas under the curve (AUC) of age, admission GCS, heart rate, tracheotomy, and platelets count were 0.678 (95% CI, 0.584-0.771), 0.799 (95% CI, 0.723-0.875), 0.652 (95% CI, 0.553-0.751), 0.776 (95% CI, 0.692-0.859), and 0.688 (95% CI, 0.606-0.770), respectively. Conclusions: Age, admission GCS score, heart rate, tracheotomy, and platelets count can be recognized as independent predictors of clinical prognosis in patients with severe TBI combined with extracranial trauma.

Effects of Blood Components and Whole Blood in a Model of Severe Trauma-Induced Coagulopathy

BACKGROUND

Plasma resuscitation ameliorates hyperfibrinolysis (HF) and trauma-induced coagulopathy (TIC). However, the use of other blood components to reduce HF has not been evaluated. Therefore, our aim was to determine the effect of individual blood components and whole blood (WB) on an in vitro model of severe HF/TIC.

METHODS

A "TIC" solution was made with 1:1 dilution of WB with saline and exacerbated with tissue plasminogen activator (tPA). Components were added in proportions equivalent to the thromboelastography (TEG) based goal-directed resuscitation used at our institution. Whole blood was added at proportions equal to what has been transfused in injured patients. Samples (n = 9) underwent citrated native and tPA-challenge (75 ng/mL) TEG with analysis of R-time, angle, MA, and LY30. Statistical analyses were completed employing the nonparametric Kruskal-Wallis and Dunn's multiple comparisons tests.

RESULTS

TIC solution, when compared to control, had a decrease in clot strength (MA 41 mm versus 51.5 mm, P < 0.01). The addition of tPA resulted in a severe coagulopathy (MA 24.5 mm versus 41 mm and LY30 52.8% versus 2.4%, P < 0.03 for all). The addition of 4U of WB improved clot strength compared to TIC + tPA (P = 0.03). No individual blood component resulted in improved fibrinolysis (P > 0.7). Cryoprecipitate improved R-time (7.5 versus 11.9 min, P < 0.01), angle (56.8 versus 30.2°) and MA (49 mm versus 36.25 mm), while platelets improved MA (44 mm versus 36.25 mm) compared to TIC + tPA (P < 0.03 for all).

CONCLUSIONS

No single blood component or volume of whole blood led to attenuation of tPA-mediated fibrinolysis in an in vitro model of TIC. Cryoprecipitate was the most effective at improving coagulation function.

The dose-dependent relationship between blood transfusions and infections after trauma: A population-based study

OBJECTIVE

The relationship between total transfusion volume and infection in the trauma patient remains unclear, especially at lower volumes of transfusion. We sought to quantify the cumulative, independent impact of transfusion within 24 hours of admission on the risk of infection in trauma patients.

METHODS

Using the Trauma Quality Improvement Program 2013 to 2016 database, we included all patients who received blood transfusions in the first 4 hours. Patients who were transferred or had incomplete/wrongly coded information on transfusion volume were excluded. Patients were divided into 20 cohorts based on the total blood product volume transfused in the first 24 hours. A composite infection variable (INF) was created, including surgical site infection, ventilator-associated pneumonia, urinary tract infection, central line associated blood stream infection, and sepsis. Univariate and stepwise multivariable logistic regression analyses were performed to study the relationship between blood transfusion and INF, controlling for demographics (e.g., age, sex), comorbidities (e.g., cirrhosis, diabetes, steroid use), severity of injury (e.g., vital signs on arrival, mechanism, Injury Severity Score), and operative and angiographic interventions.

RESULTS

Of 1,002,595 patients, 37,568 were included. The mean age was 42 ± 18.6 years, 74.6% were males, 68% had blunt trauma, and median Injury Severity Score was 25 [17-34]. Adjusting for all available confounders, odds of INF increased incrementally from 1.00 (reference, 0-2 units) to 1.23 (95% confidence interval, 1.11-1.37) for 4 units transfused to 4.89 (95% confidence interval, 2.72-8.80) for 40 units transfused. Each additional unit increased the odds of INF by 7.6%.

CONCLUSION

Transfusion of the bleeding trauma patient was associated with a dose-dependent increased risk of infectious complications. Trauma surgeons and anesthesiologists should resuscitate the trauma patient until prompt hemorrhage control while avoiding overtransfusion.

LEVEL OF EVIDENCE

Retrospective cohort study, Therapeutic IV.

Differential modulation of endothelial cell function by fresh frozen plasma

AIMS

In vivo studies suggest a positive influence of fresh frozen plasma (FFP) on endothelial properties and vascular barrier function, leading to improved outcomes in animal sepsis models as well as in major abdominal surgery. However, those effects are incompletely described. It was our aim to evaluate in vitro effects of FFP on endothelial key functions and to identify underlying mechanisms.

MATERIALS AND METHODS

Human pulmonary microvascular endothelial cells (HPMECs) were prestimulated with LPS, followed by incubation with FFP. Permeability for FITC-dextran was assessed, and intercellular gap formation was visualized. NF-κB nuclear translocation and expression of pro-inflammatory, pro-adhesion, and leakage-related genes were evaluated, and monocyte adhesion to ECs was assessed. Intracellular cAMP levels as well as phosphorylation of functional proteins were analyzed. In patients undergoing major abdominal surgery, Syndecan-1 serum levels were assessed prior to and following FFP transfusion.

KEY FINDINGS

Post-incubation of HPMVECs with FFP increased intracellular cAMP levels that had been decreased by preceding LPS stimulation. On one hand, this reduced endotoxin-mediated upregulation of IL-8, ICAM-1, VCAM-1, VEGF, and ANG-2. Impaired phosphorylation of functional proteins was restored, and intercellular cohesion and barrier function were rescued. On the other hand, NF-κB nuclear translocation as well as monocyte adhesion was markedly increased by the combination of LPS and FFP. Syndecan-1 serum levels were lower in surgery patients that were transfused with FFP compared to those that were not.

SIGNIFICANCE

Our data provide evidence for a differential modulation of crucial endothelial properties by FFP, potentially mediated by elevation of intracellular cAMP levels.

Dysregulation of the actin scavenging system and inhibition of DNase activity following severe thermal injury

Background

Circulating cell‐free DNA (cfDNA) is not found in healthy subjects, but is readily detected after thermal injury and may contribute to the risk of multiple organ failure. The hypothesis was that a postburn reduction in DNase protein/enzyme activity could contribute to the increase in cfDNA following thermal injury.

Methods

Patients with severe burns covering at least 15 per cent of total body surface area were recruited to a prospective cohort study within 24 h of injury. Blood samples were collected from the day of injury for 12 months.

Results

Analysis of blood samples from 64 patients revealed a significant reduction in DNase activity on days 1–28 after injury, compared with healthy controls. DNase protein levels were not affected, suggesting the presence of an enzyme inhibitor. Further analysis revealed that actin (an inhibitor of DNase) was present in serum samples from patients but not those from controls, and concentrations of the actin scavenging proteins gelsolin and vitamin D‐binding protein were significantly reduced after burn injury. In a pilot study of ten military patients with polytrauma, administration of blood products resulted in an increase in DNase activity and gelsolin levels.

Conclusion

The results of this study suggest a novel biological mechanism for the accumulation of cfDNA following thermal injury by which high levels of actin released by damaged tissue cause a reduction in DNase activity. Restoration of the actin scavenging system could therefore restore DNase activity, and reduce the risk of cfDNA‐induced host tissue damage and thrombosis.

A systematic review of large animal models of combined traumatic brain injury and hemorrhagic shock

Traumatic brain injury (TBI) and severe blood loss (SBL) frequently co-occur in human trauma, resulting in high levels of mortality and morbidity. Importantly, each of the individual post-injury cascades is characterized by complex and potentially opposing pathophysiological responses, complicating optimal resuscitation and therapeutic approaches. Large animal models of poly-neurotrauma closely mimic human physiology, but a systematic literature review of published models has been lacking. The current review suggests a relative paucity of large animal poly-neurotrauma studies (N = 52), with meta-statistics revealing trends for animal species (exclusively swine), characteristics (use of single biological sex, use of juveniles) and TBI models. Although most studies have targeted blood loss volumes of 35-45%, the associated mortality rates are much lower relative to Class III/IV human trauma. This discrepancy may result from potentially mitigating experimental factors (e.g., mechanical ventilation prior to or during injury, pausing/resuming blood loss based on physiological parameters, administration of small volume fluid resuscitation) that are rarely associated with human trauma, highlighting the need for additional work in this area.

Experimental Models of Endotheliopathy: Impact of Shock Severity

BACKGROUND

Hemorrhagic shock (HS) followed by resuscitation is often associated with sympathoadrenal activation (SAA) and endothelial damage (ED).

OBJECTIVE

We aimed to evaluate the impact of HS alone on the magnitude of SAA and consecutive ED, and to characterize potential targets for a standardized and reproducible model of HS-induced endotheliopathy in rats.

METHODS

Rats were subjected either to a volume-controlled HS (40% of total blood volume: v-HS group) or to a laboratory-guided HS (l-HS) targeting base deficit (BD) more than 5.5 mmol/L and/or lactate more than 2.2 mmol/L using a pressure-controlled volume loss.

RESULTS

At the end of shock, mean arterial pressure was significantly higher in the v-HS than the l-HS group (36 ± 5.6 vs. 30 ± 3.0 mmHg; P < 0.01). Base deficit and lactate were higher in l-HS than the v-HS group (BD: 9.5 ± 2.5 vs. 3.0 ± 1.0 mmol/L; P < 0.001; lactate: 4.1 ± 1.3 vs. 1.6 ± 0.6 mmol/L; P < 0.001). sVEGFR-1 and syndecan-1 were approximately 50% higher in the l-HS than the v-HS group (% changes vs. baseline: 160 ± 10 vs. 116 ± 36; P < 0.01; 170 ± 37 vs. 113 ± 27; P < 0.001). Adrenaline was 2-fold higher in l-HS than the v-HS group (1964 ± 961% vs. 855 ± 451%; P < 0.02, respectively). Moreover, linear regression analysis revealed an independent association of shock severity BD with syndecan-1 (rho = 0.55, P = 0.0005), sVEGFR1 (rho = 0.25, P < 0.05), and adrenaline (rho = 0.31, P = 0.021).

CONCLUSIONS

Our findings indicate that ED has already occurred during HS without reperfusion; intensity is strongly related to the severity of HS and consecutive SAA; and severity may appropriately be targeted and standardized in a HS model controlled by biological endpoints such as BD and/or lactate.

Fluid administration rate for uncontrolled intraabdominal hemorrhage in swine

Background

We hypothesized that slow crystalloid resuscitation would result in less blood loss and a smaller hemoglobin decrease compared to a rapid resuscitation during uncontrolled hemorrhage.

Methods

Anesthetized, splenectomized domestic swine underwent hepatic lobar hemitransection. Lactated Ringers was given at 150 or 20 mL/min IV (rapid vs. slow, respectively, N = 12 per group; limit of 100 mL/kg). Primary endpoints were blood loss and serum hemoglobin; secondary endpoints included survival, vital signs, coagulation parameters, and blood gases.

Results

The slow group had a less blood loss (1.6 vs. 2.7 L, respectively) and a higher final hemoglobin concentration (6.0 vs. 3.4 g/dL).

Conclusions

Using a fixed volume of crystalloid resuscitation in this porcine model of uncontrolled intraabdominal hemorrhage, a slow IV infusion rate produced less blood loss and a smaller hemoglobin decrease compared to rapid infusion.

Different resuscitation strategies and novel pharmacologic treatment with valproic acid in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death in young adults, and effective treatment strategies have the potential to save many lives. TBI results in coagulopathy, endothelial dysfunction, inflammation, cell death, and impaired epigenetic homeostasis, ultimately leading to morbidity and/or mortality. Commonly used resuscitation fluids such as crystalloids or colloids have several disadvantages and might even be harmful when administered in large quantities. There is a need for next-generation treatment strategies (especially in the prehospital setting) that minimize cellular damage, improve survival, and enhance neurological recovery. Pharmacologic treatment with histone deacetylase inhibitors, such as valproic acid, has shown promising results in animal studies of TBI and may therefore be an excellent example of next-generation therapy. This review briefly describes traditional resuscitation strategies for TBI combined with hemorrhagic shock and describes preclinical studies on valproic acid as a new pharmacologic agent in the treatment of TBI. It finally discusses limitations and future directions on the use of histone deacetylase inhibitors for the treatment of TBI.

Plasma First Resuscitation Reduces Lactate Acidosis, Enhances Redox Homeostasis, Amino Acid and Purine Catabolism in a Rat Model of Profound Hemorrhagic Shock

The use of aggressive crystalloid resuscitation to treat hypoxemia, hypovolemia, and nutrient deprivation promoted by massive blood loss may lead to the development of the blood vicious cycle of acidosis, hypothermia, and coagulopathy and, utterly, death. Metabolic acidosis is one of the many metabolic derangements triggered by severe trauma/hemorrhagic shock, also including enhanced proteolysis, lipid mobilization, as well as traumatic diabetes. Appreciation of the metabolic benefit of plasma first resuscitation is an important concept. Plasma resuscitation has been shown to correct hyperfibrinolysis secondary to severe hemorrhage better than normal saline. Here, we hypothesize that plasma first resuscitation corrects metabolic derangements promoted by severe hemorrhage better than resuscitation with normal saline. Ultra-high-performance liquid chromatography-mass spectrometry-based metabolomics analyses were performed to screen plasma metabolic profiles upon shock and resuscitation with either platelet-free plasma or normal saline in a rat model of severe hemorrhage. Of the 251 metabolites that were monitored, 101 were significantly different in plasma versus normal saline resuscitated rats. Plasma resuscitation corrected lactate acidosis by promoting glutamine/amino acid catabolism and purine salvage reactions. Plasma first resuscitation may benefit critically injured trauma patients by relieving the lactate burden and promoting other non-clinically measured metabolic changes. In the light of our results, we propose that plasma resuscitation may promote fueling of mitochondrial metabolism, through the enhancement of glutaminolysis/amino acid catabolism and purine salvage reactions. The treatment of trauma patients in hemorrhagic shock with plasma first resuscitation is likely not only to improve coagulation, but also to promote substrate-specific metabolic corrections.

Hemorrhagic Shock and the Microvasculature

The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.

The effect of resuscitation strategy on the longitudinal immuno-inflammatory response to blunt trauma

INTRODUCTION

Resuscitation strategies following blunt trauma have been linked to immuno-inflammatory complications leading to systemic inflammatory syndrome (SIRS), sepsis and multiple organ failure (MOF). The effect of resuscitation strategy on longitudinal inflammation marker trajectories is, however, unknown. We hypothesized that the effect of resuscitation strategy extends beyond the trauma-related coagulopathy, perhaps affecting the longitudinal immuno-inflammatory response to injury.

METHODS

We analyzed data prospectively collected for the Inflammation and Host Response to Injury (Glue Grant) study. Blood sampling for inflammation marker analyses from blunt trauma patients was done on admission days 0, 1, 4, 7, 14, 21 and 28 where applicable. Total volume transfused of packed red blood cells (PRBC), fresh frozen plasma (FFP), platelets (PLT), and crystalloids during the initial 48h was extracted, along with an analysis for an array of cytokines by Enzyme Linked Immunosorbent Assay (ELISA) technique. A within patient concentration change (WPCC) was calculated to quantify longitudinal alterations in cytokine levels, while controlling for potential confounders. To account for the multiple comparisons performed, p-values obtained from the multivariate regression model were post-hoc corrected by the false detection rate (FDR) q-value.

RESULTS

No longitudinal trajectories of inflammatory markers were found to be associated with PRBC- or PLT transfusion. Three proinflammatory cytokines (Il-1β, MIP-1β, and TNFR2) were negatively associated with volume of FFP transfused (q=0.02, q<0.001 and q=0.007 respectively), and one proinflammatory cytokine (MIP-1β) was positively associated with crystalloid infusion (q=0.005).

CONCLUSIONS

Resuscitation strategy employed following blunt trauma has limited association to longitudinal inflammation marker trajectories, with a potential association between the strategy employed and IL-1β, TNFR2, and MIP-1β trajectories, respectively.

Resuscitation for Hypovolemic Shock

Hemorrhage is the leading cause of preventable deaths in trauma patients. After presenting a brief history of hemorrhagic shock resuscitation, this article discusses damage control resuscitation and its adjuncts. Massively bleeding patients in hypovolemic shock should be treated with damage control resuscitation principles including limited crystalloid, whole blood or balance blood component transfusion to permissive hypotension, preventing hypothermia, and stopping bleeding as quickly as possible.

Optimal Fluid Therapy for Traumatic Hemorrhagic Shock

The resuscitation of traumatic hemorrhagic shock has undergone a paradigm shift in the last 20 years with the advent of damage control resuscitation (DCR). Major principles of DCR include minimization of crystalloid, permissive hypotension, transfusion of a balanced ratio of blood products, and goal-directed correction of coagulopathy. In particular, plasma has replaced crystalloid as the primary means for volume expansion for traumatic hemorrhagic shock. Predicting which patient will require DCR by prompt and accurate activation of a massive transfusion protocol, however, remains a challenge.

Fresh Frozen Plasma Modulates Brain Gene Expression in a Swine Model of Traumatic Brain Injury and Shock: A Network Analysis

BACKGROUND

Resuscitation with fresh frozen plasma (FFP) decreases brain lesion size and swelling in a swine model of traumatic brain injury and hemorrhagic shock. We hypothesized that brain gene expression profiles after traumatic brain injury and hemorrhagic shock would be modulated by FFP resuscitation.

STUDY DESIGN

Fifteen swine underwent a protocol of traumatic brain injury and hemorrhagic shock and 2 hours of shock followed by resuscitation with FFP, normal saline, or hetastarch (5/group). After 6 hours, brain RNA was isolated and hybridized onto a porcine gene ST 1.1 microarray. Weighted gene correlation network analysis was used to identify clusters of highly coexpressed genes. Principal component analysis identified cluster eigenvectors, indicating overall direction and magnitude of cluster gene expression. Using linear regression, cluster eigenvectors were associated with treatment as well as brain lesion size and swelling. Results were post-hoc corrected using false discovery rate. Relevant gene clusters were subjected to pathway analysis using the Reactome tool.

RESULTS

Network analysis identified 322 gene expression clusters (total of 12,462 coexpressed genes). Fresh frozen plasma resuscitation (but not normal saline or hetastarch) was positively associated with 2 distinct gene clusters (termed A and B) comprising 493 genes. Gene expression in both clusters was negatively associated with brain swelling, and cluster B was also negatively associated with lesion size. Pathway analysis revealed an upregulation of genes involved in metabolic and platelet signaling, as well as collagen formation and downregulation of inflammation.

CONCLUSIONS

Fresh frozen plasma resuscitation in this model was associated with downregulation of inflammatory pathway genes and expression of gene clusters mapping to increased metabolic and platelet signaling, which, in turn, was reversely associated with brain swelling.

Shock-induced systemic hyperfibrinolysis is attenuated by plasma-first resuscitation

BACKGROUND

We developed a hemorrhagic shock animal model to replicate an urban prehospital setting where resuscitation fluids are limited to assess the effect of saline versus plasma in coagulopathic patients. An in vitro model of whole blood dilution with saline exacerbated tissue plasminogen activator (tPA)-mediated fibrinolysis, while plasma dilution did not change fibrinolysis. We hypothesize that shock-induced hyperfibrinolysis can be attenuated by resuscitation with plasma while exacerbated by saline.

METHODS

Sprague-Dawley rats were hemorrhaged to a mean arterial pressure of 25 mm Hg and maintained in shock for 30 minutes. Animals were resuscitated with either normal saline (NS) or platelet-free plasma (PFP) with a 10% total blood volume bolus, followed by an additional 5 minutes of resuscitation with NS to increase blood pressure to a mean arterial pressure of 30 mm Hg. Animals were observed for 15 minutes for the assessment of hemodynamic response and survival. Blood samples were analyzed with thrombelastography paired with protein analysis.

RESULTS

The median percentage of total blood volume shed per group were similar (NS, 52.5% vs. PFP, 55.7; p = 0.065). Survival was 50% in NS compared with 100% in PFP. The change in LY30 and tPA levels from baseline to shock was similar between groups (LY30 PFP, 10; interquartile range [IQR], 4.3-11.2; NS, 4.5; IQR, 4.1-14.2; p = 1.00; tPA PFP, 16.6 ng/mL; IQR, 13.7-27.8; NS, 22.4; IQR, 20.1-25.5; p = 0.240). After resuscitation, the median change in LY30 was greater in the NS group (13.5; IQR, 3.5-19.9) compared with PFP (-4.9%; IQR, -9.22 to 0.25 p = 0.004), but tPA levels did not significantly change (NS, 1.4; IQR, -6.2 to 7.1 vs. PFP, 1.7; IQR, -5.2 to 6.8; p = 0.699).

CONCLUSION

Systemic hyperfibrinolysis is driven by hypoperfusion and associated with increased levels of tPA. Plasma is a superior resuscitation fluid to NS in a prehospital model of severe hemorrhagic shock as it attenuates hyperfibrinolysis and improves systemic perfusion.

Current Concepts in Orthopedic Management of Multiple Trauma

Multiple trauma patients frequently present challenging clinical scenarios with musculoskeletal injuries being the most common indications for surgical procedures in these patients. Despite our substantial knowledge, a universally approved objective definition for “multiple trauma” is yet to be delineated. Several controversial aspects of economics, pathophysiology, animal models, diagnosis, management and outcome of patients with multiple trauma have recently been explored and although some progress has been made, it seems that the available evidence is still inconclusive in some occasions. This manuscript revisits several current concepts of multiple trauma that have been the focus of recent investigation. We aim to provide the reader with an updated perspective based on the most recently published literature in the field of multiple trauma.

Optimal fluid resuscitation in trauma: type, timing, and total

PURPOSE OF REVIEW

This review article explores the recent literature regarding the optimal type and amount of intravenous fluids for the trauma patient from the time of injury through their ICU stay. It discusses damage control principles as well as targeted resuscitation utilizing new technology.

RECENT FINDINGS

In the prehospital arena, intravenous fluids have been associated with worse patient outcomes due to increased coagulopathy and time to definitive care. Once in the trauma bay, damage control resuscitation principles apply to the severely injured patient. Large volume crystalloid infusion increases mortality. The best patient outcomes have been found with transfusion of blood products in a ratio that closely mimics whole blood. Thrombelastography is a useful adjunct in resuscitation and can help guide the judicious use of blood products. New technology can help providers ascertain when a patient is appropriately resuscitated by determining adequate global and regional perfusion.

SUMMARY

During the resuscitation of the acutely injured patient, crystalloids should be limited in favor of blood components. Damage control principles apply until definitive hemostasis is obtained, at which point the focus should change to targeted resuscitation using traditional global endpoints of resuscitation in conjunction with determinants of regional perfusion.

Mechanisms of trauma-induced coagulopathy

PURPOSE OF REVIEW

Hemorrhage is the leading cause of potentially preventable death following injury. Excessive and uncontrolled bleeding, commonly referred to as trauma-induced coagulopathy (TIC), affects a quarter of all trauma patients and is associated with substantial injuries, increased transfusion requirements, and poor outcomes. Recent data have contributed to our current understanding of the molecular mechanisms driving TIC.

RECENT FINDINGS

The current literature offers evidence supporting proposed mechanisms that induce TIC, such as platelet dysfunction, endogenous anticoagulation, endothelial activation, fibrinogen modifications, and hyperfibrinolysis. However, the majority of these data are mere associations; causative data are slowly unfolding through the utilization of animal models of hemorrhagic shock coupled with prospective observational clinical studies.

SUMMARY

As both clinical and basic science research expands our understanding of TIC, trauma patient care is improving substantially. Future studies should focus on the interplay between the coagulation pathways whose simultaneous or codependent dysregulation could offer the most advantageous points for intervention.

Hypothermia and valproic acid activate prosurvival pathways after hemorrhage

BACKGROUND

Therapeutic hypothermia (hypo) and valproic acid (VPA, a histone deacetylase inhibitor) have independently been shown to be protective in models of trauma and hemorrhagic shock but require logistically challenging doses to be effective. Theoretically, combined treatment may further enhance effectiveness, allowing us to use lower doses of each modality. The aim of this study was to determine whether a combination of mild hypo and VPA treatments would offer better cytoprotection compared with that of individual treatments in a hemorrhage model.

MATERIALS AND METHODS

Male Sprague-Dawley rats were subjected to 40% volume-controlled hemorrhage, kept in shock for 30 min, and assigned to one of the following treatment groups: normothermia (36°C-37°C), hypo (30 ± 2°C), normothermia + VPA (300 mg/kg), and hypo + VPA (n = 5 per group). After 3 h of observation, the animals were sacrificed, liver tissue was harvested and subjected to whole cell lysis, and levels of key proteins in the prosurvival Akt pathway were measured using Western blot.

RESULTS

Activation of the proapoptotic protein cleaved caspase-3 was significantly lower in the combined treatment group relative to normothermia (P < 0.05). Levels of the prosurvival Bcl-2 was significantly higher in the combined treatment group relative to sham, normothermia, and normothermia + VPA groups (P < 0.005). The downstream prosurvival protein phospho-GSK-3β was significantly higher in the sham, hypo, and combined treatment groups compared with that in normothermia groups with or without VPA (P < 0.05). Levels of the prosurvival β-catenin were significantly higher in the combined treatment group relative to normothermia (P < 0.01).

CONCLUSIONS

This is the first in vivo study to demonstrate that combined treatment with VPA and hypo offers better cytoprotection than these treatments given independently.

Early resuscitation with fresh frozen plasma for traumatic brain injury combined with hemorrhagic shock improves neurologic recovery

BACKGROUND

We have shown that early administration of fresh frozen plasma (FFP) reduces the size of brain lesions 6 hours after injury in a large animal model of traumatic brain injury (TBI) and hemorrhagic shock (HS). To examine long-term outcomes, we hypothesized that early treatment with FFP would result in faster neurologic recovery and better long-term outcomes in a combined TBI and HS model.

STUDY DESIGN

Anesthetized Yorkshire swine underwent combined TBI and volume-controlled hemorrhage (40% blood volume). After 2 hours of shock, animals were randomized (n = 5/group) to normal saline (3× shed blood) or FFP (1× shed blood) treatment. A neurologic severity score was assessed for 30 days. Magnetic resonance imaging of the brain was performed at days 3, 10, and 24. Cognitive function was tested by training animals to retrieve food from color-coded boxes.

RESULTS

Neurologic impairment was lower and speed of recovery was considerably faster in the FFP-treated animals. There was a trend toward a smaller lesion size in FFP-treated animal at days 3 and 10, but this did not reach statistical significance. Both groups reached baseline performance on the cognitive testing; however, FFP-treated animals were able to participate, on average, 8 days earlier due to quicker recovery.

CONCLUSIONS

This is the first study to demonstrate the beneficial effects of FFP treatment in a long-term survival model of combined TBI and HS. Our data show that early treatment with FFP substantially attenuates the degree of neurologic impairment, improves the rate of recovery, and preserves the cognitive functions.

Treatment with a histone deacetylase inhibitor, valproic acid, is associated with increased platelet activation in a large animal model of traumatic brain injury and hemorrhagic shock

BACKGROUND

We have previously shown that resuscitation with fresh frozen plasma (FFP) in a large animal model of traumatic brain injury (TBI) and hemorrhagic shock (HS) decreases the size of the brain lesion, and that addition of a histone deacetylase inhibitor, valproic acid (VPA), provides synergistic benefits. In this study, we hypothesized that VPA administration would be associated with a conservation of platelet function as measured by increased platelet activation after resuscitation.

MATERIALS AND METHODS

Ten swine (42-50 kg) were subjected to TBI and HS (40% blood loss). Animals were left in shock for 2 h before resuscitation with either FFP or FFP+VPA (300 mg/kg). Serum levels of platelet activation markers transforming growth factor beta, CD40 L, P-selectin, and platelet endothelial cell adhesion molecule (PECAM) 1 were measured at baseline, postresuscitation, and after a 6-h observation period. Platelet activation markers were also measured in the brain whole cell lysates and immunohistochemistry.

RESULTS

Circulating P-selectin levels were significantly higher in the FFP+VPA group compared with the FFP alone group (70.85±4.70 versus 48.44±7.28 ng/mL; P<0.01). Likewise, immunohistochemistry data showed elevated P-selectin in the VPA treatment group (22.30±10.39% versus 8.125±3.94%, P<0.01). Serum sCD40L levels were also higher in the FFP+VPA group (3.21±0.124 versus 2.38±0.124 ng/mL; P<0.01), as was brain sCD40L levels (1.41±0.15 versus 1.22±0.12 ng/mL; P=0.05). Circulating transforming growth factor beta levels were elevated in the FFP+VPA group, but this did not reach statistical significance (11.20±1.46 versus 8.09±1.41 ng/mL; P=0.17). Brain platelet endothelial cell adhesion molecule 1 levels were significantly lower in the FFP+VPA group compared with the FFP group (5.22±2.00 pg/mL versus 7.99±1.13 pg/mL; P=0.03).

CONCLUSIONS

In this clinically relevant large animal model of combined TBI+HS, the addition of VPA to FFP resuscitation results in an early upregulation of platelet activation in the circulation and the brain. The previously observed neuroprotective effects of VPA may be due to a conservation of platelet function as measured by a higher platelet activation response after resuscitation.