Prolyl hydroxylase domain inhibitor is an effective pre-hospital pharmaceutical intervention for trauma and hemorrhagic shock.

Pre-hospital potentially preventable trauma related deaths are mainly due to hypoperfusion-induced tissue hypoxia leading to irreversible organ dysfunction at or near the point of injury or during transportation prior to receiving definitive therapy. The prolyl hydroxylase domain (PHD) is an oxygen sensor that regulates tissue adaptation to hypoxia by stabilizing hypoxia inducible factor (HIF). The benefit of PHD inhibitors (PHDi) in the treatment of anemia and lactatemia arises from HIF stabilization, which stimulates endogenous production of erythropoietin and activates lactate recycling through gluconeogenesis. The results of this study provide insight into the therapeutic roles of MK-8617, a pan-inhibitor of PHD-1, 2, and 3, in the mitigation of lactatemia in anesthetized rats with polytrauma and hemorrhagic shock. Additionally, in an anesthetized rat model of lethal decompensated hemorrhagic shock, acute administration of MK-8617 significantly improves one-hour survival and maintains survival at least until 4 h following limited resuscitation with whole blood (20% EBV) at one hour after hemorrhage. This study suggests that pharmaceutical interventions to inhibit prolyl hydroxylase activity can be used as a potential pre-hospital countermeasure for trauma and hemorrhage at or near the point of injury.

A novel, quantitative clot retraction assay to evaluate platelet function.

Blood platelets are crucial to prevent excessive bleeding following injury to blood vessels. Platelets are crucial for the formation of clots and for clot strength. Platelet activation involves aggregation, attachment to fibrin and clot retraction. Most assays that address platelet function measure platelet aggregation, not clot retraction. Here, we describe a 96-well-based clot retraction assay that requires a relatively short runtime and small sample volume. The assay involves continuous optical density monitoring of platelet-rich plasma that is activated with thrombin. The data can be analyzed using time-series analytical tools to generate quantitative information about different phases of clot formation and clot retraction. The assay demonstrated good repeatability and reproducibility and was robust to different calcium concentrations. Impairment of platelet bioenergetics, actin polymerization, fibrin interaction, and signaling significantly affected clot retraction and was detected and showed good agreement with light transmission aggregometry, suggesting that clot retraction is predictive of platelet function. Using this microplate clot retraction assay, we showed a significant difference in platelets stored in autologous plasma compared with platelet additive solution after 7 days of room temperature storage.

Platelets are cell fragments in the blood that are necessary for clot formation. They are crucial to preventing excessive bleeding following trauma. To form clots, platelets clump (aggregate) and attach to fibrin protein and cells inside the blood vessels to form strong web-like structures. Platelets also contract to pull the edges of the wound close. Most measurements of platelet function involve aggregation. This paper focuses on platelet contraction. Here, we describe a new assay to measure platelets contraction that is repeatable and reproducible. The assay uses standard and common laboratory equipment and can be performed by most laboratory personnel and has the potential to detect clinical pathologies of clot formation. The assay could be developed for bedside patient care where platelet function could be assessed rapidly and assist in the diagnosis of coagulation and platelet disorders.

Metabolic effects of radiation on red blood cells from cold stored whole blood.

BACKGROUND: The risk of military and civilian radiation exposure is increasing, and determining the effects of exposure is a high priority. Irradiation of the nearby blood supply after a nuclear event may impede mobilization of blood products for resuscitation at a time of great need. RBCs are administered to patients with trauma and hemorrhage to transport and deliver oxygen and avoid tissue hypoxia. Here we determine the effects of ionizing radiation on the energy metabolome of RBCs isolated from cold stored whole blood to determine if their stability is compromised by radiation exposure. STUDY DESIGN AND METHODS: Whole blood from healthy volunteers was subjected to 0, 25, or 75 Gy of X-irradiation, and stored at 4°C. RBCs were isolated from stored WB at 0, 1, 7, 14, and 21 days of storage. The levels of extracted Krebs cycle intermediates, nicotinamide adenine dinucleotides, and phosphorylated derivatives of adenosine and guanosine were determined by tandem mass spectroscopy. RESULTS: Irradiation at either 25Gy or 75Gy had no significant effect on any parameter measured compared to control (0Gy). However, there was a significant change over time in storage for ATP, GDP, and guanosine. DISCUSSION: Irradiation at doses up to 75Gy had no effect on the energy metabolome of RBCs prepared from blood stored at 4°C for up to 21 days, suggesting that the RBC energy metabolome is not affected by radiation exposure and the blood can still be used for resuscitation in trauma patients.

Effects of radiation exposure and storage on the energy metabolome of platelets in whole blood.

BACKGROUND: Exposure to radiation through battlefield use of nuclear weapons, terrorist attacks or accidents at nuclear power plants is a current concern for the military. Beyond the risk of exposure to personnel is the intentional or accidental irradiation of our blood banking supply system. It is unknown how large doses of ionizing radiation affect storage of blood and blood products, including platelets. The major function of platelets is clot formation which includes aggregation, shape change, vesicle release, and fibrinogen attachment; these tasks require a significant amount of energy. Here, we determine whether the ionizing radiation effects the energy metabolome of platelets in storage. STUDY DESIGN AND METHODS: Fresh whole blood from healthy volunteers was subjected to 0, 25, or 75Gy of X-irradiation, and stored at 4°C. Platelets were isolated from stored WB at 0, 1, 7, 14, and 21 days of storage. Krebs cycle intermediates, nicotinamide adenine dinucleotides, and the tri-, di, and mono- phosphorylated versions of adenosine and guanosine were extracted and measured by tandem mass spectroscopy. RESULTS: Irradiation at either 25Gy or 75Gy had no significant effect on the amount of any metabolite measured compared to control (0Gy). However, there was a significant fall over time in storage for most of the metabolites measured. DISCUSSION: These data show that irradiation at high doses has no effect on the concentration of the energy metabolome of platelets derived from whole blood stored in 4°C for up to 21 days and suggests that platelets can maintain their metabolome even after radiation exposure.

High-dose radiation exposure of cold-stored whole blood does not affect hemostatic function.

BACKGROUND: Whole blood (WB) transfusion is routinely used to resuscitate severely injured military trauma patients. Blood can be stored refrigerated while still maintaining reasonable function but is susceptible to environmental influences, including radiation exposure. Immune-compromised patients are transfused with irradiated blood to inactivate donor lymphocyte function (25 Gy per Association for the Advancement of Blood and Biotherapies [AARB] standard 5.7.3.2). However, there is limited information on function of WB exposed to high radiation doses. OBJECTIVE: This study aimed to determine if stored irradiated WB still retains function. This will be important if the stored blood supply is exposed to radiation in a combat situation or mass casualty incident when the need for blood will be high. METHODS: Whole blood collected from healthy donors was irradiated at 0, 25, or 75 Gy and stored at 4°C. Blood cell count, blood gas chemistry, thromboelastometry, platelet aggregation, and reactive oxygen species were measured before irradiation and at 1, 7, and 14 days of storage. Irradiated WB was compared with nonirradiated WB controls. RESULTS: Irradiated WB stored for up to 14 days was not significantly different than nonirradiated WB in most of the parameters measured. Stored blood showed expected changes associated with functional decline at longer storage times, but irradiation did not hasten the decline. There was a significant change in potassium and sodium ion concentrations after irradiation, but the functional relevance is not clear. CONCLUSION: High-dose irradiation had little effect on stored WB. Although there were changes in plasma sodium and potassium levels, there was little to no effect on hemostasis and blood cell viability. This suggests that stored blood subjected to a radiation event generating at least a dose of 75 Gy is still suitable for transfusion, which could be particularly important in the event of a mass casualty event where a large amount of blood is needed.

A natural history study of coagulopathy in a porcine 40% total body surface area burn model reveals the time-dependent significance of functional assays.

Various studies have reported discordant results on the magnitude and direction of burn-induced coagulopathy (BIC), which has recently been associated with multiple organ dysfunction syndrome (MODS) and death. The increased mechanistic understanding of BIC is due, in part, to novel assays that have expanded the armamentarium beyond traditional tests like PT and aPTT. Still, BIC is a dynamic process, and the progression is difficult to define in the thermally-injured. To this end, we aimed to enhance the understanding of burn-induced coagulation abnormalities by employing functional assessments of platelet aggregation, viscoelastic kinetics, and thrombin generation in an extensive burn model in swine. Anesthetized Yorkshire pigs sustained 40% total body surface area (TBSA) full-thickness contact burns and recovered in metabolic cages. Blood was collected at baseline (BL), as well as 6, 24, and 48 h after injury. A significant effect of burn (P < 0.0001) was seen on platelets, with mild thrombocytopenia apparent at 24 h. While slight decreases in aPTT were not significant, rotational thromboelastometry (ROTEM) analysis revealed hypercoagulation 6 and 24 h after burn by a decreased clotting time. Maximum clot firmness increased after burn, but was not statistically significant until 48 h. Hypercoagulation was not supported by platelet aggregation, as the response to ADP was greatly and persistently diminished, and the response to collagen was unchanged. Endogenous thrombin potential was significantly reduced at 6 and 24 h after burn (P < 0.0001), and also correlated with a number of ROTEM parameters and collagen-induced platelet aggregation. In contrast, PT was not correlated with other measured parameters. Taken together, novel coagulation parameters may be more sensitive than PT in characterizing coagulopathy in the setting of burns. The data presented herein makes initial strides to report the natural history of several of these variables over time in a large animal model of extensive burns, indicating early hypercoagulability followed by hypocoagulation. Future work will elucidate the effects of standard of care.

Intravenous administration of mesenchymal stromal cells leads to a dose-dependent coagulopathy and is unable to attenuate acute traumatic coagulopathy in rats.

BACKGROUND: Mesenchymal stromal cells (MSCs) express surface tissue factor (TF), which may affect hemostasis and detract from therapeutic outcomes of MSCs if administered intravenously. In this study, we determine a safe dose of MSCs for intravenous (IV) administration and further demonstrate the impact of IV-MSC on acute traumatic coagulopathy (ATC) in rats. METHODS: Tissue factor expression of rat bone marrow-derived mesenchymal stromal cell (BMSC) or adipose-derived mesenchymal stromal cell (AMSC) was detected by immunohistochemistry and enzyme-linked immunosorbent assay. The coagulation properties were measured in MSC-treated rat whole blood, and blood samples were collected from rats after IV administration of MSCs. Acute traumatic coagulopathy rats underwent polytrauma and 40% hemorrhage, followed by IV administration of 5 or 10 million/kg BMSCs (BMSC-5, BMSC-10), or vehicle at 1 hour after trauma. RESULTS: Rat MSCs expressed TF, and incubation of rat BMSCs or AMSCs with whole blood in vitro led to a significantly shortened clotting time. However, a dose-dependent prolongation of prothrombin time with reduction in platelet counts and fibrinogen was found in healthy rat treated with IV-MSCs. Bone marrow-derived mesenchymal stromal cells at 5 million/kg or less led to minimal effect on hemostasis. Mesenchymal stromal cells were not found in circulation but in the lungs after IV administration regardless of the dosage. Acute traumatic coagulopathy with prolonged prothrombin time was not significantly affected by 5 or 10 million/kg BMSCs. Intravenous administration of 10 million/kg BMSCs led to significantly lower fibrinogen and platelet counts, while significantly higher levels of lactate, wet/dry weight ratio, and leukocyte infiltration in the lung were present compared with BMSC-5 or vehicle. No differences were seen in immune or inflammatory profiles with BMSC treatment in ATC rats, at least in the acute timeframe. CONCLUSION: Intravenous administration of MSCs leads to a risk of coagulopathy associated with a dose-dependent reduction in platelet counts and fibrinogen and is incapable of restoring hemostasis of rats with ATC after polytrauma and hemorrhagic shock.

Hemostatic capacity of canine chilled whole blood over time.

OBJECTIVE: To determine the hemostatic potential of canine chilled whole blood maintained at clinically relevant storage conditions. DESIGN: In vitro experimental study. SETTING: Government blood and coagulation research laboratory and government referral veterinary hospital. ANIMALS: Ten healthy Department of Defense military working dogs. INTERVENTIONS: One unit of fresh whole blood was collected from each of 10 military working dogs using aseptic technique. Blood was maintained in a medical-grade refrigerator for 28 days at 4°C (39°F) and analyzed before refrigeration (day 0) and after (days 2, 4, 7, 9, 11, 14, 21, and 28). MEASUREMENTS AND MAIN RESULTS: Ten units of canine blood were analyzed with whole blood platelet aggregation, thromboelastography, CBC, biochemical analysis, blood gas, and prothrombin/activated partial thromboplastin/fibrinogen assay. Clotting strength of chilled blood was maintained up to 21 days despite significant decreases in platelet aggregation to ADP, collagen, or γ-thrombin, significant prolongation of prothrombin and activated partial thromboplastin times, and reduced speed of clot formation (K time, alpha angle). Fibrinogen concentration, WBC, RBC, and platelet counts did not change over time. CONCLUSIONS: Chilled canine whole blood loses a small percentage of clot strength through 21 days of refrigerated storage. Further research is needed to determine if this hemostatic potential is clinically relevant in hemorrhaging dogs who require surgical intervention or are exposed to traumatic events.

Use of Specialized Pro-Resolving Mediators to Alleviate Cold Platelet Storage Lesion.

BACKGROUND: Cold-stored platelets are an attractive option for treatment of actively bleeding patients due to a reduced risk of septic complications and preserved hemostatic function compared to conventional room temperature-stored platelets. However, refrigeration causes increased platelet activation and aggregate formation. Specialized pro-resolving mediators (SPMs), cell signaling mediators biosynthesized from essential fatty acids, have been shown to modulate platelet function and activation. In this study, we sought to determine if SPMs could be used to inhibit cold-stored platelet activation. METHODS: Platelets were collected from healthy donors (n = 4-7) and treated with SPMs (resolvin E1 [RvE1], maresin 1 [MaR1], and resolvin D2 [RvD2]) or vehicle (VEH; 0.1% EtOH). Platelets were stored without agitation in the cold and assayed on Days 0 and 7 of storage for platelet activation levels using flow cytometry, platelet count, aggregation response using impedance aggregometry, and nucleotide content using mass spectrometry. RESULTS: Compared to VEH, SPM treatment inhibited GPIb shedding (all compounds), significantly reduced both PS exposure and activation of GPIIb/IIIa receptor (RvD2, MaR1), and preserved aggregation response to TRAP (RvD2, MaR1) after 7 days of storage. Similar to untreated cold-stored platelets, SPM-treated samples did not preserve platelet counts or block the release of P-Selectin. Nucleotide content was unaffected by SPM treatment in cold-stored platelets. CONCLUSIONS: SPM treatment, particularly Mar1 and RvD2, led to reduced platelet activation and preserved platelet function after 7 days of storage in the cold. Future work is warranted to better elucidate the mechanism of action of SPMs on cold platelet function and activation.

Microvascular and Systemic Impact of Resuscitation with PEGylated Carboxyhemoglobin-Based Oxygen Carrier or Hetastarch in a Rat Model of Transient Hemorrhagic Shock.

BACKGROUND: Hemorrhage is the leading cause of preventable, traumatic death. Currently, prehospital resuscitation fluids provide preload but not oxygen-carrying capacity-a critical blood function that mitigates microvascular ischemia and tissue hypoxia during hemorrhagic shock. Solutions containing polymerized hemoglobin have been associated with vasoactive and hypertensive events. A novel hemoglobin-based oxygen carrier, modified with PEGylation and CO moieties (PEG-COHb), may overcome these limitations. OBJECTIVES: To evaluate the systemic and microcirculatory effects of PEG-COHb as compared with the 6% hetastarch in a rat model of hemorrhagic shock. METHODS: Male Sprague Dawley rats (N = 20) were subjected to severe, controlled, hemorrhagic shock. Animals were randomized to 20% estimated blood-volume resuscitation with either 6% hetastarch or PEG-COHb. Continuous, invasive, cardiovascular measurements, and arterial blood gases were measured. Microcirculatory measurements of interstitial oxygenation (PISFO2) and vasoactivity helped model oxygen delivery in the spinotrapezius muscle using intravital and phosphorescence quenching microscopy. RESULTS: Hemorrhage reduced mean arterial pressure (MAP), arteriolar diameter, and PISFO2, and increased lactate 10-fold in both groups. Resuscitation with both PEG-COHb and hetastarch improved cardiovascular parameters. However, PEG-COHb treatment resulted in higher MAP (P < 0.001), improved PISFO2 (14 [PEG-COHb] vs. 5 [hetastarch] mmHg; P < 0.0001), lower lactate post-resuscitation (P < 0.01), and extended survival from 90 to 142 min (P < 0.001) as compared with the hetastarch group. CONCLUSIONS: PEG-COHb improved MAP PISFO2, lactate, and survival time as compared with 6% hetastarch resuscitation. Importantly, hypertension and vasoactivity were not detected in response to PEG-COHb resuscitation supporting further investigation of this resuscitation strategy.

Severe Trauma and Hemorrhage Leads to Platelet Dysfunction and Changes in Cyclic Nucleotides in The Rat.

INTRODUCTION: Rats subjected to polytrauma and hemorrhage develop a coagulopathy that is similar to acute coagulopathy of trauma in humans, and is associated with a rise in prothrombin time and a fall in clot strength. Because platelet aggregation accounts for a major proportion of clot strength, we set out to characterize the effects of polytrauma on platelet function. METHODS: Sprague-Dawley rats were anesthetized with isoflurane. Polytrauma included laparotomy and damage to 10 cm of the small intestines, right and medial liver lobes, right leg skeletal muscle, femur fracture, and hemorrhage (40% of blood volume). No resuscitation was given. Blood samples were taken before and after trauma for the measurement of impedance electrode aggregometry, and intracellular levels of cyclic adenosine and guanosine monophosphate (cAMP, cGMP), inositol trisphosphate (IP3), and adenosine and guanosine triphosphates (ATP, GTP). RESULTS: Polytrauma significantly increased the response of collagen (24%) and thrombin (12%) to stimulate platelet aggregation. However, aggregation to adenosine diphosphate (ADP) or arachidonic acid (AA) was significantly decreased at 2 (52% and 46%, respectively) and 4 h (45% and 39%). Polytrauma and hemorrhage also led to a significant early rise in cAMP (101 ±â€Š11 to 202 ±â€Š29 pg/mL per 1,000 platelets), mirrored by a decrease in cGMP (7.8 ±â€Š0.9 to 0.6 ±â€Š0.5). In addition, there was a late fall in ATP (8.1 ±â€Š0.7 to 2.2 ±â€Š0.6 ng/mL per 1,000 platelets) and GTP (1.5 ±â€Š0.2 to 0.3 ±â€Š0.1). IP3 rose initially, and then fell back to baseline. CONCLUSIONS: Polytrauma and hemorrhage led to a deficit in the platelet aggregation response to ADP and AA after trauma, likely due to the early rise in cAMP, and a later fall in energy substrates, and may explain the decrease in clot strength and impaired hemostasis observed after severe trauma.

Effect of tranexamic acid administration on acute traumatic coagulopathy in rats with polytrauma and hemorrhage.

Trauma and hemorrhagic shock can lead to acute traumatic coagulopathy (ATC) that is not fully reversed by prehospital resuscitation as simulated with a limited volume of fresh whole blood (FWB) in a rat model. Tranexamic Acid (TXA) is used as an anti-fibrinolytic agent to reduce surgical bleeding if administered prior to or during surgery, and to improve survival in trauma if given early after trauma. It is not clear from the existing clinical literature whether TXA has the same mechanism of action in both settings. This study sought to explore the molecular mechanisms of TXA activity in trauma and determine whether administration of TXA as a supplement to FWB resuscitation could attenuate the established ATC in a rat model simulating prehospital resuscitation of polytrauma and hemorrhagic shock. In a parallel in-vitro study, the effects on clotting assays of adding plasmin at varying doses along with either simultaneous addition of TXA or pre-incubation with TXA were measured, and the results suggested that maximum anti-fibrinolytic effect of TXA on plasmin-induced fibrinolysis required pre-incubation of TXA and plasmin prior to clot initiation. In the rat model, ATC was induced by polytrauma followed by 40% hemorrhage. One hour after trauma, the rats were resuscitated with FWB collected from donor rats. Vehicle or TXA (10mg/kg) was given as bolus either before trauma (TXA-BT), or 45min after trauma prior to resuscitation (TXA-AT). The TXA-BT group was included to contrast the coagulation effects of TXA when used as it is in elective surgery vs. what is actually feasible in real trauma patients (TXA-AT group). A single dose of TXA prior to trauma significantly delayed the onset of ATC from 30min to 120min after trauma as measured by a rise in prothrombin time (PT). The plasma d-dimer as well as plasminogen/fibrinogen ratio in traumatized liver of TXA-BT were significantly lower as compared to vehicle and TXA-AT. Wet/dry weight ratio and leukocytes infiltration of lungs were significantly decreased only if TXA was administrated later, prior to resuscitation (TXA-AT). In conclusion: Limited prehospital trauma resuscitation that includes FWB and TXA may not correct established systemic ATC, but rather may improve overall outcomes of resuscitation by attenuation of acute lung injury. By contrast, TXA given prior to trauma reduced levels of fibrinolysis at the site of tissue injury and circulatory d-dimer, and delayed development of coagulopathy independent of reduction of fibrinogen levels following trauma. These findings highlight the importance of early administration of TXA in trauma, and suggest that further optimization of dosing protocols in trauma to exploit TXA's various sites and modes of action may further improve patient outcomes.

An in vitro pilot study of apheresis platelets collected on Trima Accel system and stored in T-PAS+ solution at refrigeration temperature (1-6°C).

BACKGROUND: Using platelet additive solution (PAS) to dilute fibrinogen during long-term cold storage of platelets (PLTs) decreases PLT activation and increases functional PLT shelf life. We performed a randomized, paired study to assess the in vitro quality of PLTs stored in the cold in T-PAS+ for up to 18 days evaluated against PLTs stored under currently allowable conditions (5-day room temperature-stored PLTs [RTP] and 3-day cold-stored PLTs [CSP]). STUDY DESIGN AND METHODS: PLTs were collected from healthy volunteers (n = 10) and diluted to 65% T-PAS+/35% plasma before cold storage. Double-dose apheresis PLTs (in 100% plasma) were collected from the same donors and split into two bags (one bag RTP, one bag CSP). All bags were sampled on the day of collection (Day 0). CSP and RTP bags were sampled on Days 3 and 5, respectively. T-PAS+ samples were assessed on Days 3, 5, 14, 16, and 18 of storage for metabolism, hemostatic function, and activation. RESULTS: After 18 days of storage in T-PAS+, pH was 6.71 ± 0.04, PLT count was comparable to Day 3 CSP, PLT function (aggregation and clot strength) was comparable to Day 5 RTP, and PLT activation was significantly increased. CONCLUSION: Refrigerated PLTs stored in T-PAS+ for 18 days met FDA pH standards. Functional metrics suggest activity of T-PAS+-stored PLTs and the potential to contribute to hemostasis throughout 18 days of storage. Extending the shelf life of PLTs would increase access to hemostatic resuscitation for bleeding patients in military and civilian settings.

Polytrauma independent of therapeutic intervention alters the gastrointestinal microbiome.

BACKGROUND: This study characterizes the gastrointestinal (GI) microbiome in a pre-clinical polytrauma hemorrhage model. METHODS: Rats (n = 6) were anesthetized, hemorrhaged 20% of their blood volume, and subjected to a femur fracture and crush injuries to the small intestine, liver, and limb skeletal muscle without resuscitation. Fecal samples were collected pre-injury and 2 h post-injury. Purified DNA from the samples underwent 16s rRNA sequencing for microbial quantification. Bacterial diversity analysis and taxonomic classification were performed. RESULTS: Following injury, the gut microbial composition was altered with a shift in beta diversity and significant differences in the relative abundance of taxa. The relative abundance of the families Lachnospiraceae and Mogibacteriaceae was increased at 2 h, while Barnesiellaceae and Bacteroidaceae were decreased. Alpha diversity was unchanged. CONCLUSIONS: The GI microbiome is altered in rats subjected to a polytrauma hemorrhage model at 2 h post-injury in the absence of antibiotics or therapeutic interventions.

Immunopathological response to severe injury: platelet activation and the Th-17 immune response.

: Alterations in coagulation, inflammation and immunity are associated with major injury. As platelets have both coagulation and immune functions, the aim of this study is to correlate platelet activation with the immunoinflammatory response in trauma and burn patients. Blood samples were drawn from trauma and burn patients and healthy volunteers. Platelet (sCD40L) and coagulation (D-dimers) activation, cytokines and inflammatory markers were assessed. sCD40L, D-dimers and cytokines were elevated in both injury groups. Overall, sCD40L levels correlated with interleukin (IL)-6 and tumour necrosis factor-alpha. Subanalysis revealed a correlation between sCD40L and IL-17a in the healthy volunteers and burn groups, but not the trauma group. A parallel activation of platelets and the inflammatory response occurs postinjury. However, in trauma patients, a potential critical interrelationship between platelet activation and the Th-17 response appears to be lacking, which may contribute to coagulopathic and immunoinflammatory complications and warrants further study.

Platelets derived from fresh and cold-stored whole blood participate in clot formation in rats with acute traumatic coagulopathy.

The in vitro haemostatic functions of fresh whole blood (FWB) are well preserved after cold storage. This study aimed to determine whether platelets derived from FWB and stored whole blood (SWB) contribute to clot formation in tissue injury after transfusion into coagulopathic rats with polytrauma/haemorrhage (T/H). The rats were resuscitated 1 h after trauma with FWB or SWB collected from green fluorescence protein (GFP) transgenic rats. After transfusion, a liver incision was made and the tissue was collected 10 min after injury to identify GFP+ platelets by immunohistochemistry. In comparison to FWB, platelet aggregation to adenosine diphosphate and protease-activated receptor-4 was reduced by 35% and 20%, and clotting time was shortened by 25% in SWB. After transfusion, SWB led to a significant increase in platelet activation as measured by an elevation of CD62P and phosphatidylserine expression. The platelets from SWB were in a higher activation state, and showed higher clearance rate and formation of platelet-leucocyte aggregates than those from FWB after transfusion. Platelets from both FWB and SWB were equivalently incorporated into the clot at the incisional site, as determined by co-localization of CD61 and GFP. This study suggests that SWB contributes to haemostatic function and is an effective alternative resource to treat trauma patients.

Prehospital Blood Transfusion During Aeromedical Evacuation of Trauma Patients in Israel: The IDF CSAR Experience.

BACKGROUND: Data regarding the effect of prehospital blood administration to trauma patients during short-to-moderate time evacuations is scarce. The Israel Air Force Airborne Combat Search and Rescue is the only organization that deals with aeromedical evacuation for both military and civilian casualties in Israel and the only one with the ability to give blood in the prehospital setting. METHODS: Data on packed red blood cells (PRBCs) administration in the evacuation missions from January 2003 to June 2010 were analyzed and actual transfusion practice was compared to clinical practice guidelines (CPGs). RESULTS: Over the studied 101 months, a total of 1,721 patients were evacuated by Combat Search and Rescue. Of these, 87 (5.1%) trauma patients were transfused with PRBC. Demographics included 83% male and 17% female with a median age of 23 years. Main mechanisms of injury included gunshot wounds (36%), motor vehicle accidents (28%), and blast injuries (24%) with an average of 2.6 injured regions per casualty. The most commonly injured body regions included lower extremities (52%), chest (45%), and abdomen (38%). Overall, 10 (11%) casualties died. Lifesaving intervention included tourniquets (27%), endotracheal intubation (24%), tube thoracostomy (24%), and needle thoracostomy (21%) times. For 98% of the patients, clinical judgment led to administration of red blood cells before indicated by the CPG. The heart rate tended to decrease during the evacuation, whereas there was no clear trend in systolic or diastolic blood pressure or shock index. CONCLUSIONS: In our aeromedical experience, transfusion of PRBCs for trauma patients was safe, feasible, and most likely beneficial. PRBCs were administered according to the flight surgeons' clinical judgment and not in complete adherence to CPGs in most cases. Data collected from this and similar studies worldwide have led to change in CPGs with the shift from hypertensive resuscitation to hypotensive-hemostatic Remote Damage Control Resuscitation.

Acute traumatic coagulopathy: The elephant in a room of blind scientists.

Acute traumatic coagulopathy (ATC) is the failure of coagulation homeostasis that can rapidly arise following traumatic injury, hemorrhage, and shock; it is associated with higher injury severity, coagulation abnormalities, and increased blood transfusions. Acute traumatic coagulopathy has historically been defined by a prolonged prothrombin time, although newer, more informative measurements of hemostatic function have been used to improve diagnosis and support clinical decision making. The underlying biochemical mechanisms of and best practice therapeutics for ATC remain under active investigation because of its significant correlation to poor outcomes. The wide range of hypothesized mechanisms for ATC results from the large number of symptoms, phenotypes, and altered states in these patients as observed by multiple research groups. Much like the ancient fable of blind men describing an elephant from their limited perspectives, the limited nature of clinical and laboratory tools used to diagnose coagulopathy or evaluate hemostatic function has made finding causation difficult. The prolonged prothrombin time, degree of fibrinolysis, depletion of coagulation factors and inhibitors, and general failure of the blood have all been identified as being primary indicators for ATC. Therapeutic interventions including recombinant coagulation factors, antifibrinolytics, and blood products have been used with varying degrees of success as they are used to address specific symptoms. To truly understand the causes of ATC, research efforts must recognize the complexity of the hemostatic system and get to the heart of the matter by answering the question: "Is ATC a pathological condition that develops from the observed deficiencies in coagulation, fibrinolysis, and autoregulation, or is ATC an adaptive response generated as the body attempts to restore perfusion and avoid massive organ failure?" Because patient management must proceed without definitive answers regarding the entire causative chain, the current therapeutic focus should be on using what knowledge has been gained to the patient's advantage: control hemorrhage, maintain appropriate homeostatic balances of coagulation proteins, and restore oxygen perfusion.