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.

Acute intensive care unit resuscitation of severely injured trauma patients: Do we need a new strategy?

BACKGROUND: Unlike recent advances in blood product resuscitation, intravenous crystalloid (IVF) use after intensive care unit (ICU) admission in hemorrhagic shock has received less attention and current recommendations are based on limited evidence. To address this knowledge gap, we aimed to determine associations between IVF administration during acute ICU resuscitation and outcomes. We hypothesized that larger IVF volumes are associated with worse outcomes. METHODS: We linked our trauma registry with electronic health record data (2012-2015) to identify adults with an initial lactate level of ≥4 mmol/L and documented lactate normalization (≤2 mmol/L), excluding those with isolated head Abbreviated Injury Scale score ≥3. We focused on the period from ICU admission to lactate normalization, analyzing duration, volume of IVF, and proportion of volume as 1-L boluses. We used linear regression to determine associations with ICU length of stay and duration of mechanical ventilation in survivors, and logistic regression to identify associations with acute kidney injury and home discharge while adjusting for important covariates. RESULTS: We included 337 subjects. Median time to lactate normalization was 15 hours (interquartile range, 7-25 hours), and median IVF volume was 3.7 L (interquartile range, 1.5-6.4 L). The fourfold difference between the upper and lower quartiles of both duration and volume remained after stratifying by injury severity. Hourly volumes tapered over time but persistently aggregated at 0.5 and 1 L, with 167 subjects receiving at least one 0.5-L bolus for 6 hours after ICU admission. Administration of larger volumes was associated with longer ICU length of stay and duration of mechanical ventilation, as well as acute kidney injury. CONCLUSION: There is substantial variation in volume administered during acute ICU resuscitation, both absolutely and temporally, despite accounting for injury severity. Administration of larger volumes during acute ICU resuscitation is associated with worse outcomes. There is an opportunity to improve outcomes by further investigating and standardizing this important phase of care. LEVEL OF EVIDENCE: Therapeutic/care management, level IV.

Critical traumatic brain injury is associated with worse coagulopathy.

OBJECTIVES: As thromboelastography (TEG) becomes the standard of care in patients with hemorrhagic shock (HS), an association between concomitant traumatic brain injury (TBI) and coagulopathy by TEG parameters is not well understood and is thus investigated. METHODS: Retrospective analysis of trauma registry data at a single level 1 trauma center of 772 patients admitted with head Abbreviated Injury Scale (AIS) score of 3 and TEG studies between 2014 and 2017. Patients were stratified to moderate-severe TBI by head AIS scores of 3 and 4 (435 patients) and critical TBI by head AIS score of 5 (328 patients). Hemorrhagic shock was defined by base deficit of 4 or shock index of 0.9. Statistical analysis with unpaired t tests compared patients with critical TBI with patients with moderate-severe TBI, and patients were grouped by presence or absence of HS. A comparison of TBI data with conventional coagulation studies was also evaluated. RESULTS: In the setting of HS, critical TBI versus moderate-severe TBI was associated with longer R time (p = 0.004), longer K time (p < 0.05), less acute angle (p = 0.001), and lower clot strength and stability (maximum amplitude [MA]) (p = 0.01). Worse TBI did not correlate with increased fibrinolysis by clot lysis measured by the percentage decrease in amplitude at 30 minutes after MA (p = 0.3). Prothrombin time and international normalized ratio failed to demonstrate more severe coagulopathy, while partial thromboplastin time was found to correlate with severity of TBI (p = 0.01). In patients with critical TBI, the presence of HS correlated with a statistically significant worsening of all parameters (p < 0.05) except for clot lysis measured by the percentage decrease in amplitude at 30 minutes after MA (LY-30). CONCLUSION: Thromboelastography demonstrates that, with and without hemorrhagic shock, critical TBI correlates with a significant worsening of traumatic coagulopathy in comparison with moderate/severe TBI. In HS, critical TBI correlates with impaired clot initiation, impaired clot kinetics, and impaired platelet-associated clot strength and stability versus parameters found in moderate-severe TBI. Hemorrhagic shock correlates with worse traumatic coagulopathy in all evaluated patient groups with TBI. Conventional coagulation studies underestimate TBI-associated coagulopathy. Traumatic brain injury-associated coagulopathy is not associated with fibrinolysis. LEVEL OF EVIDENCE: Prognostic/epidemiological, level IV; prognostic/epidemiological, level III.

Identification of unique microRNA expression patterns in bone marrow hematopoietic stem and progenitor cells after hemorrhagic shock and multiple injuries in young and old adult mice.

BACKGROUND: After severe trauma, the older host experiences more dysfunctional hematopoiesis of bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs), and dysfunctional differentiation of circulating myeloid cells into effective innate immune cells. Our main objective was to compare BM HSPC microRNA (miR) responses of old and young mice in a clinically relevant model of severe trauma and shock. METHODS: C57BL/6 adult male mice aged 8 to 12 weeks (young) and 18 to 24 months (old) underwent multiple injuries and hemorrhagic shock (polytrauma [PT]) that engenders the equivalent of major trauma (Injury Severity Score, >15). Pseudomonas pneumonia (PNA) was induced in some young and old adult mice 24 hours after PT. MicroRNA expression patterns were determined from lineage-negative enriched BM HSPCs isolated from PT and PT-PNA mice at 24 and 48 hours postinjury, respectively. Genome-wide expression and pathway analyses were also performed on bronchoalveolar lavage (BAL) leukocytes from both mouse cohorts. RESULTS: MicroRNA expression significantly differed among all experimental conditions (p < 0.05), except for old-naive versus old-injured (PT or PT-PNA) mice, suggesting an inability of old mice to mount a robust early miR response to severe shock and injury. In addition, young adult mice had significantly more leukocytes obtained from their BAL, and there were greater numbers of polymorphonuclear cells compared with old mice (59.8% vs. 2.2%, p = 0.0069). Despite increased gene expression changes, BAL leukocytes from old mice demonstrated a more dysfunctional transcriptomic response to PT-PNA than young adult murine BAL leukocytes, as reflected in predicted upstream functional pathway analysis. CONCLUSION: The miR expression pattern in BM HSPCs after PT (+/-PNA) is dissimilar in old versus young adult mice. In the acute postinjury phase, old adult mice are unable to mount a robust miR HSPC response. Hematopoietic stem and progenitor cell miR expression in old PT mice reflects a diminished functional status and a blunted capacity for terminal differentiation of myeloid cells.

Compensatory reserve detects subclinical shock with more expeditious prediction for need of life-saving interventions compared to systolic blood pressure and blood lactate.

INTRODUCTION: We conducted a prospective observational study on 205 trauma patients at a level I trauma facility to test the hypothesis that a compensatory reserve measurement (CRM) would identify higher risk for progression to shock and/or need a life-saving interventions (LSIs) earlier than systolic blood pressure (SBP) and blood lactate (LAC). METHODS: A composite outcome metric included blood transfusion, procedural LSI, and mortality. Discrete measures assessed as abnormal (ab) were SBP <90 mmHg, CRM <60%, and LAC >2.0. A graded categorization of shock was defined as: no shock (normal [n] SBP [n-SBP], n-CRM, n-LAC); sub-clinical shock (ab-CRM, n-SBP, n-LAC); occult shock (n-SBP, ab-CRM, ab-LAC); or overt shock (ab-SBP, ab-CRM, ab-LAC). RESULTS: Three patients displayed overt shock, 53 displayed sub-clinical shock, and 149 displayed no shock. After incorporating lactate into the analysis, 86 patients demonstrated no shock, 25 were classified as sub-clinical shock, 91 were classified as occult shock, and 3 were characterized as overt shock. Each shock subcategory revealed a graded increase requiring LSI and transfusion. Initial CRM was associated with progression to shock (odds ratio = 0.97; p < .001) at an earlier time than SBP or LAC. CONCLUSIONS: Initial CRM uncovers a clinically relevant subset of patients who are not detected by SBP and LAC. Our results suggest CRM could be used to more expeditiously identify injured patients likely to deteriorate to shock, with requirements for blood transfusion or procedural LSI.

Hemorrhagic shock and hemostatic resuscitation in canine trauma.

Hemorrhage is a significant cause of death among military working dogs and in civilian canine trauma. While research specifically aimed at canine trauma is limited, many principles from human trauma resuscitation apply. Trauma with significant hemorrhage results in shock and inadequate oxygen delivery to tissues. This leads to aberrations in cellular metabolism, including anaerobic metabolism, decreased energy production, acidosis, cell swelling, and eventual cell death. Considering blood and endothelium as a single organ system, blood failure is a syndrome of endotheliopathy, coagulopathy, and platelet dysfunction. In severe cases following injury, blood failure develops and is induced by inadequate oxygen delivery in the presence of hemorrhage, tissue injury, and acute stress from trauma. Severe hemorrhagic shock is best treated with hemostatic resuscitation, wherein blood products are used to restore effective circulating volume and increase oxygen delivery to tissues without exacerbating blood failure. The principles of hemostatic resuscitation have been demonstrated in severely injured people and the authors propose an algorithm for applying this to canine patients. The use of plasma and whole blood to resuscitate severely injured canines while minimizing the use of crystalloids and colloids could prove instrumental in improving both mortality and morbidity. More work is needed to understand the canine patient that would benefit from hemostatic resuscitation, as well as to determine the optimal resuscitation strategy for these patients.

Prehospital whole blood reduces early mortality in patients with hemorrhagic shock.

BACKGROUND: Low titer O+ whole blood (LTOWB) is being increasingly used for resuscitation of hemorrhagic shock in military and civilian settings. The objective of this study was to identify the impact of prehospital LTOWB on survival for patients in shock receiving prehospital LTOWB transfusion. STUDY DESIGN AND METHODS: A single institutional trauma registry was queried for patients undergoing prehospital transfusion between 2015 and 2019. Patients were stratified based on prehospital LTOWB transfusion (PHT) or no prehospital transfusion (NT). Outcomes measured included emergency department (ED), 6-h and hospital mortality, change in shock index (SI), and incidence of massive transfusion. Statistical analyses were performed. RESULTS: A total of 538 patients met inclusion criteria. Patients undergoing PHT had worse shock physiology (median SI 1.25 vs. 0.95, p < .001) with greater reversal of shock upon arrival (-0.28 vs. -0.002, p < .001). In a propensity-matched group of 214 patients with prehospital shock, 58 patients underwent PHT and 156 did not. Demographics were similar between the groups. Mean improvement in SI between scene and ED was greatest for patients in the PHT group with a lower trauma bay mortality (0% vs. 7%, p = .04). No survival benefit for patients in prehospital cardiac arrest receiving LTOWB was found (p > .05). DISCUSSION: This study demonstrated that trauma patients who received prehospital LTOWB transfusion had a greater improvement in SI and a reduction in early mortality. Patient with prehospital cardiac arrest did not have an improvement in survival. These findings support LTOWB use in the prehospital setting. Further multi-institutional prospective studies are needed.

Successful mild brain hypothermia therapy followed by targeted temperature management for pediatric hemorrhagic shock and encephalopathy syndrome.

OBJECTIVE: Hemorrhagic shock and encephalopathy syndrome (HSES) is the most severe form of acute encephalopathy that progresses rapidly, often resulting in death or severe neurological sequelae. We report the case of a 4-year-old girl with HSES with shock and impaired consciousness. PATIENT AND METHODS: Blood test results showed hypercytokinemia, and the 4-year-old patient was immediately admitted to the intensive care unit. Within 4 h of symptom onset, she received mild brain hypothermia therapy with a target body temperature of 35°C. Methylprednisolone pulse, high dose immunoglobulin, and large doses of circulatory drugs were administered. RESULTS: After 72 h of brain hypothermia therapy, targeted temperature management with a target body temperature between 36°C and 37°C was continued for 96 h. The patient was diagnosed with HSES based on acute encephalopathy with shock, hypercytokinemia, low platelet count, coagulation disorder, renal damage, and intestinal bleeding. Magnetic resonance imaging results revealed no signs of any specific acute encephalopathy. She was discharged without neurological sequelae 28 days after symptom onset. CONCLUSIONS: Mild brain hypothermia therapy initiated in the early stages followed by targeted temperature management may be an effective way to improve neurological outcomes in children suffering from HSES.

Lactate as a mediator of prehospital plasma mortality reduction in hemorrhagic shock.

BACKGROUND: Prehospital plasma transfusion in trauma reduces mortality. However, the underlying mechanism remains unclear. Reduction in shock severity may play a role. Lactate correlates with physiologic shock severity and mortality after injury. Our objective was to determine if prehospital plasma reduces lactate and if this contributes to the mortality benefit of plasma. METHODS: Patients in the Prehospital Air Medical Plasma trial in the upper quartile of injury severity (Injury Severity Score, >30) were included to capture severe shock. Trial patients were randomized to prehospital plasma or standard care resuscitation (crystalloid ± packed red blood cells). Regression determined the associations between admission lactate, 30-day mortality, and plasma while adjusting for demographics, prehospital crystalloid, time, mechanism, and injury characteristics. Causal mediation analysis determined what proportion of the effect of plasma on mortality is mediated by lactate reduction. RESULTS: A total of 125 patients were included. The plasma group had a lower adjusted admission lactate than standard of care group (coefficient, -1.64; 95% confidence interval [CI], -2.96 to -0.31; p = 0.02). Plasma was associated with lower odds of 30-day mortality (odds ratio [OR], 0.27; 95% CI, 0.08-0.90; p = 0.03). When adding lactate to this model, the effect of plasma on 30-day mortality was no longer significant (OR, 0.36; 95% CI, 0.07-1.88; p = 0.23), while lactate was associated with mortality (OR, 1.74 per 1 mmol/L increase; 95% CI, 1.10-2.73; p = 0.01). Causal mediation demonstrated 35.1% of the total effect of plasma on 30-day mortality was mediated by the reduction in lactate among plasma patients. CONCLUSION: Prehospital plasma is associated with reduced 30-day mortality and lactate in severely injured patients. More than one third of the effect of plasma on mortality is mediated by a reduction in lactate. Thus, reducing the severity of hemorrhagic shock appears to be one mechanism of prehospital plasma benefit. Further study should elucidate other mechanisms and if a dose response exists. LEVEL OF EVIDENCE: Therapeutic, level II.

Idarucizumab (PRAXBIND®) as a sole reversal agent in an unstable hemorrhagic shock patient on an unknown anticoagulant with elevated protime/international normalized ratio (PT/INR).

Dabigatran is a direct oral anticoagulant thrombin inhibitor approved for stroke prophylaxis in patients with non-valvular atrial fibrillation and prophylaxis or treatment of venous thromboembolism. Since approval, there has been increasing concern regarding bleeding risk, predominantly in the elderly population and those with renal disease. We present a case of an 85-year-old female with an unknown medication history, shortness of breath and severe anemia due to an upper gastrointestinal bleed. Laboratory abnormalities were significant for INR 6.43 and serum creatinine 2.21 mg/dL. While in the emergency department the patient decompensated requiring intubation, aggressive crystalloid resuscitation, blood products and initiation of vasopressors. The inability to distinguish between warfarin- and dabigatran-induced coagulopathies paired with the lack of medical information complicated selection of the appropriate anticoagulation reversal agent. In an attempt to prevent a prothrombotic state, prothrombin complex concentrates (PCC) were held and reversal was accomplished with idarucizumab alone, although warfarin-induced coagulopathy remained a possibility. 30 min after administration, repeat PT/INR was 16.1 s and 1.55, respectively. It was later confirmed that the patient was on sole dabigatran therapy. This case highlights the potential for dabigatran to cause extreme elevation in PT/INR in patients with acute renal failure, which may mimic warfarin-induced coagulopathy. Further, it demonstrates significant, rapid correction of abnormal coagulation assays following administration of idarucizumab in a patient with severe INR elevation and suspected dabigatran use.

Resolvin D1 Attenuates the Organ Injury Associated With Experimental Hemorrhagic Shock.

OBJECTIVE: To evaluate the potential changes in the plasma levels of resolvin D1 (RvD1) in patients with trauma and hemorrhage. Having found that trauma results in a profound reduction in plasma RvD1 in patients, we have then investigated the effects of RvD1 on the organ injury and dysfunction associated with hemorrhagic shock (HS) in the rat. BACKGROUND: HS is a common cause of death in trauma due to excessive systemic inflammation and multiple organ failure. RvD1 is a member of the resolvin family of pro-resolution mediators. METHODS: Blood samples were drawn from critically injured patients (n = 27, ACITII-prospective observational cohort study) within 2 hours of injury for targeted liquid chromatography tandem mass spectrometry. HS rats (removal of blood to reduce arterial pressure to 30 ±â€Š2 mm Hg, 90 minutes, followed by resuscitation) were treated with RvD1 (0.3 or 1 µg/kg intravenous (i.v.)) or vehicle (n = 7). Parameters of organ injury and dysfunction were determined. RESULTS: Plasma levels of RvD1 (mg/dL) were reduced in patients with trauma+HS (0.17 ±â€Š0.08) when compared with healthy volunteers (0.76 ±â€Š0.25) and trauma patients (0.62 ±â€Š0.20). In rats with HS, RvD1 attenuated the kidney dysfunction, liver injury, and tissue ischemia. RvD1 also reduced activation of the nuclear factor (NF)-κB pathway and reduced the expression of pro-inflammatory proteins such as inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1ß, and interleukin-6. CONCLUSION: Plasma RvD1 is reduced in patients with trauma-HS. In rats with HS, administration of synthetic RvD1 on resuscitation attenuated the multiple organ failure associated with HS by a mechanism that involves inhibition of the activation of NF-κB.

Thrombin Generation Kinetics are Predictive of Rapid Transfusion in Trauma Patients Meeting Critical Administration Threshold.

INTRODUCTION: We hypothesize that a patient (pt) with accelerated thrombin generation, time to peak height (ttPeak), will have a greater odds of meeting critical administration threshold (CAT) criteria (> 3 packed red blood cell [pRBC] transfusions [Tx] per 60 min interval), within the first 24 h after injury, independent of international normalized ratio (INR). METHODS: In a prospective cohort study, trauma patients were enrolled over a 4.5-year period and serial blood samples collected at various time points. We retrospectively stratified pts into three categories: CAT+, CAT- but receiving some pRBC Tx, receiving no Tx within the first 24 h. Blood collected prior to Tx was analyzed for thrombin generation parameters and prothrombin time (PT)/INR. RESULTS: A total of 484 trauma pts were analyzed: injury severity score = 13 [7,22], age = 48 [28, 64] years, and 73% male. Fifty pts met criteria for CAT+, 64 pts CAT-, and 370 received no Tx. Risk factors for meeting CAT+: decreased arrival systolic blood pressure (OR 2.82 [2.17, 3.67]), increased INR (OR 2.09, [1.66, 2.62]) and decreased time to peak OR 2.27 [1.74, 2.95]). These variables remained independently associated with increased risk of requiring Tx in a multivariable logistic model, after adjusting for sex and trauma type. CONCLUSIONS: Pts in hemorrhagic shock, who meet CAT+ criteria, are characterized by accelerated thrombin generation. In our multivariable analysis, both ttPeak and PT/INR have a complementary role in predicting those injured patients who will require a high rate of Tx.

Admission Lactate and Base Deficit in Predicting Outcomes of Pediatric Trauma.

BACKGROUND: To compare admission lactate and base deficit (BD), which physiologically reflect early hemorrhagic shock, as outcome predictors of pediatric trauma. METHODS: We reviewed the data of children with trauma who visited a Korean academic hospital from 2010 through 2018. Admission lactate and BD were compared between children with and without primary outcomes. The outcomes included in-hospital mortality, early (≤24 h) transfusion, and early surgical interventions for the torso or major vessels. Subsequently, performances of lactate and BD in predicting the outcomes were compared using receiver operating characteristic curves. Logistic regressions were conducted to identify the independent associations of the two markers with each outcome. RESULTS: Of the 545 enrolled children, the mortality, transfusion, and surgical interventions occurred in 7.0%, 43.5%, and 14.9%, respectively. Cutoffs of lactate and BD for each outcome were as follows: mortality, 5.1 and 6.7 mmol/L; transfusion, 3.2 and 4.9 mmol/L; and surgical interventions, 2.9 and 5.2 mmol/L, respectively. No significant differences were found in the areas under the curve for each outcome. Of the two markers, a lactate of >5.1 mmol/L was associated with mortality (adjusted odds ratio, 6.43; 95% confidence interval, 2.61-15.84). A lactate of >3.2 mmol/L (2.82; 1.65-4.83) and a BD of >4.9 mmol/L (2.32; 1.32-4.10) were associated with transfusion, while only a BD of >5.2 mmol/L (2.17; 1.26-3.75) was done with surgical interventions. CONCLUSIONS: In pediatric trauma, lactate is more strongly associated with mortality. In contrast, BD may have a marginally stronger association with the need for hemorrhage-related procedures.

Involvement of TRPV1-containing peripheral sensory efferents in hemodynamic responses in a rat hemorrhagic shock model.

BACKGROUND: Mechanisms underlying hemodynamic disturbance in hemorrhagic shock are not completely understood. Transient receptor potential vanilloid 1-expressing afferents are involved in hemorrhagic shock pathology, and transient receptor potential vanilloid 1 antagonist, capsazepine, acts on the central nervous system to improve mortality in a rat hemorrhagic shock model. In contrast, transient receptor potential vanilloid 1-positive efferents promote vasoactive reactions through the release of neuropeptides, including calcitonin gene-related peptides. This study aimed to investigate whether transient receptor potential vanilloid 1-positive peripheral sensory efferents are involved in hemodynamic responses after hemorrhagic shock. METHODS: Male rats underwent hemorrhagic shock (mean arterial pressure 30 mm Hg for 90 min, followed by resuscitation for 30 min) and received capsazepine (5 µM/kg) 30 min after shock induction. A separate cohort of rats subjected to hemorrhagic shock received hCGRP8-37 (300 µg/kg), a calcitonin gene-related peptide receptor antagonist, at 30, 60, or 90 minutes after shock induction. The 24-hour survival rate, mean arterial pressure, heart rate, arterial blood gas, and plasma calcitonin gene-related peptide levels were measured. Tissue blood flow and oxygenation both in the mesentery and skeletal muscle were also assessed. RESULTS: Capsazepine treatment prevented the hemorrhagic shock-induced increase in plasma calcitonin gene-related peptide levels, and hCGRP8-37 treatment improved the 24-h survival rates after hemorrhagic shock at a time-dependent manner. The hCGRP8-37- or capsazepine-treated rats exhibited tissue oxygenation and metabolic conditions comparable to those in control rats at the end of the experiment. CONCLUSION: Transient receptor potential vanilloid 1 plays a crucial role in hemodynamic responses to hemorrhagic shock, partly via calcitonin gene-related peptide release, involved in its peripheral sensory-efferent functions. The hCGRP8-37 appears to improve peripheral circulatory failure, which may be useful as adjunct treatment after hemorrhagic shock.

Elevated cytokine, chemokine, and growth and differentiation factor-15 levels in hemorrhagic shock and encephalopathy syndrome: A retrospective observational study.

Patients with hemorrhagic shock and encephalopathy syndrome (HSES) have a high early mortality rate, which may be caused by a 'cytokine storm'. However, there is little information on how cytokines and chemokines change over time in these patients. We aimed to describe the characteristics of HSES by examining changes in serum biomarker levels over time. Six patients with HSES were included. We retrospectively evaluated their clinical course and imaging/laboratory data. We measured serum levels of multiple cytokines [interleukin 1ß (IL-1ß), IL-2, IL-4, IL-6, IL-10, IL-17, interferon-gamma, and tumor necrosis factor alpha], chemokines (IL-8, monocyte chemoattractant protein-1, interferon-inducible protein-10), and growth and differentiation factor (GDF)-15. The highest cytokine and chemokine levels were noted in the first 24 h, and decreased thereafter. The GDF-15 level was markedly high. Cytokine, chemokine, and GDF-15 levels were significantly higher in patients with HSES than in controls in the first 24 h, except for IL-2 and IL-4. Patients with HSES have high inflammatory cytokine and chemokine levels, a high GDF-15 level in the first 24 h, and high lactate levels. Our study provides new insights on the pathophysiology of HSES, a detailed clinical picture of patients with HSES, and potential biomarkers.

Hypocalcemia in trauma patients: A systematic review.

BACKGROUND: During hemorrhagic shock and subsequent resuscitation, pathways reliant upon calcium such as platelet function, intrinsic and extrinsic hemostasis, and cardiac contractility are disrupted. The objective of this systematic review was to examine current literature for associations between pretransfusion, admission ionized hypocalcemia, and composite outcomes including mortality, blood transfusion requirements, and coagulopathy in adult trauma patients. METHODS: This review was reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. We searched Ovid MEDLINE and grey literature from database inception till May 3, 2020. Case series and reports were excluded. Reference lists of appraised studies were also screened for articles that the aforementioned databases might not have captured. The Newcastle-Ottawa Scale was used to assess study quality. RESULTS: A total of 585 abstracts were screened through database searching and alternative sources. Six unique full-text studies were reviewed, of which three were excluded. Admission ionized hypocalcemia was present in up to 56.2% of the population in studies included in this review. Admission ionized hypocalcemia was also associated with increased mortality in all three studies, with increased blood transfusion requirements in two studies, and with coagulopathy in one study. CONCLUSION: Hypocalcemia is a common finding in shocked trauma patients. While an association between admission ionized hypocalcemia and mortality, blood transfusion requirements, and coagulopathy has been identified, further prospective trials are essential to corroborating this association. LEVEL OF EVIDENCE: Systematic review, level III.

A road map from single-cell transcriptome to patient classification for the immune response to trauma.

Immune dysfunction is an important factor driving mortality and adverse outcomes after trauma but remains poorly understood, especially at the cellular level. To deconvolute the trauma-induced immune response, we applied single-cell RNA sequencing to circulating and bone marrow mononuclear cells in injured mice and circulating mononuclear cells in trauma patients. In mice, the greatest changes in gene expression were seen in monocytes across both compartments. After systemic injury, the gene expression pattern of monocytes markedly deviated from steady state with corresponding changes in critical transcription factors, which can be traced back to myeloid progenitors. These changes were largely recapitulated in the human single-cell analysis. We generalized the major changes in human CD14+ monocytes into 6 signatures, which further defined 2 trauma patient subtypes (SG1 vs. SG2) identified in the whole-blood leukocyte transcriptome in the initial 12 hours after injury. Compared with SG2, SG1 patients exhibited delayed recovery, more severe organ dysfunction, and a higher incidence of infection and noninfectious complications. The 2 patient subtypes were also recapitulated in burn and sepsis patients, revealing a shared pattern of immune response across critical illness. Our data will be broadly useful to further explore the immune response to inflammatory diseases and critical illness.

Freeze-dried platelets promote clot formation, attenuate endothelial cell permeability, and decrease pulmonary vascular leak in a murine model of hemorrhagic shock.

BACKGROUND: Hemorrhagic shock (HS) and trauma induce endothelial barrier compromise, inflammation, and aberrant clotting. We have shown that fresh human platelets (Plts) and Plt extracellular vesicles mitigate vascular leak in murine models of injury. Here, we investigate the potential of freeze-dried platelets (FDPlts) to attenuate pulmonary vascular permeability, decrease inflammation, and promote clotting in a murine model of HS. METHODS: Human FDPlts were characterized using in vitro assays of Plt marker expression, aggregation, coagulation, and endothelial cell permeability. An intravital model of vascular injury in the mouse cremaster muscle was used to assess the ability of FDPlts to incorporate into clots. Mouse groups subjected to controlled hemorrhage for 90 minutes were (1) lactated Ringer solution (LR), (2) FDPlts, (3) fresh human Plts, (4) murine whole blood (WB), and (5) shams (only instrumented). Hemorrhagic shock mouse endpoints included coagulation, pulmonary vascular permeability, and lung injury. RESULTS: Freeze-dried Plts expressed Plt-specific markers and retained functionality similar to fresh Plts. In in vitro assays of Plt aggregation, differences were noted. In vivo, FDPlts and Plts were found to incorporate into clots in postcapillary venules in the mouse cremaster muscle. Hemorrhagic shock mice resuscitated with LR displayed increased pulmonary vascular permeability compared with sham (sham, 686.6 ± 359.7; shock-LR, 2,637 ± 954.7; p = 0.001), and treatment with FDPlts or WB attenuated permeability compared with shock: shock-FDPlts, 1,328 ± 462.6 (p = 0.05), and shock-WB, 1,024 ± 370.5 (p = 0.0108). However, human Plts (Days 1-3) did not attenuate vascular leak in HS mice compared with shock-LR (shock-Plts, 3,601 ± 1,581; p = 0.33). CONCLUSION: FDPlts contribute to clot formation similar to fresh human Plts. FDPlts also attenuated vascular permeability in vitro and in vivo. Mouse WB resuscitation but not fresh human Plts attenuated vascular permeability after HS. These data suggest that the effect of FDPlts may be a suitable alternative to fresh Plts in modulating hemostasis and the endotheliopathy associated with injury.

Quantitative Assessment of Blood Lactate in Shock: Measure of Hypoxia or Beneficial Energy Source.

Blood lactate concentration predicts mortality in critically ill patients and is clinically used in the diagnosis, grading of severity, and monitoring response to therapy of septic shock. This paper summarizes available quantitative data to provide the first comprehensive description and critique of the accepted concepts of the physiology of lactate in health and shock, with particular emphasis on the controversy of whether lactate release is simply a manifestation of tissue hypoxia versus a purposeful transfer ("shuttle") of lactate between tissues. Basic issues discussed include (1) effect of nonproductive lactate-pyruvate exchange that artifactually enhances flux measurements obtained with labeled lactate, (2) heterogeneous tissue oxygen partial pressure (Krogh model) and potential for unrecognized hypoxia that exists in all tissues, and (3) pathophysiology that distinguishes septic from other forms of shock. Our analysis suggests that due to exchange artifacts, the turnover rate of lactate and the lactate clearance are only about 60% of the values of 1.05 mmol/min/70 kg and 1.5 L/min/70 kg, respectively, determined from the standard tracer kinetics. Lactate turnover reflects lactate release primarily from muscle, gut, adipose, and erythrocytes and uptake by the liver and kidney, primarily for the purpose of energy production (TCA cycle) while the remainder is used for gluconeogenesis (Cori cycle). The well-studied physiology of exercise-induced hyperlactatemia demonstrates massive release from the contracting muscle accompanied by an increased lactate clearance that may occur in recovering nonexercising muscle as well as the liver. The very limited data on lactate kinetics in shock patients suggests that hyperlactatemia reflects both decreased clearance and increased production, possibly primarily in the gut. Our analysis of available data in health and shock suggests that the conventional concept of tissue hypoxia can account for most blood lactate findings and there is no need to implicate a purposeful production of lactate for export to other organs.

Antishock Characteristics of Erythrocyte-mediated Endoplasmic Reticulum Stress in Macrophages in Severe Hemorrhagic Shock Environment Based on TLR9-cGAS-STING-IFN Signal Axis.

This study aimed to investigate the protective effects of erythrocyte-mediated endoplasmic reticulum (ER) stress in macrophages in hemorrhagic shock. An hemorrhagic shock model was established in male BALB/c mice. Animals were randomly divided into three groups (n = 8): control group (A), erythrocyte reinfusion group (B), and TLR9 inhibition group (C). Eight healthy BALB/c mice were also included as group N (n = 8). Mice in group A were not treated, while mice in groups B and C were transfused with red blood cells separated from the blood of mice in group N. Flow cytometry was used to detect the expression of erythrocyte surface protein TLR9 in each group. Immunofluorescence assay was used to analyze the distribution and relative expression of protein STING in macrophages. Flow cytometry was used to analyze the expression of STING, ATF6, and IRE1 in macrophages. Enzyme-linked immunosorbent assay was used to analyze the levels of inflammatory signal molecules, including IFN-α, IFN-ß, IL-6, CCL4, CCL5, and IL-6. FITC-Annexin V was used to analyze the apoptosis of immune cells (macrophages) in mouse blood samples and to detect the concentration of calcium ions in erythrocyte cytoplasm. The results showed that the expression of erythrocyte surface protein TLR9; the distribution of STING-positive cells in macrophages; the expressions of STING, ATF6, and IRE1 in macrophages; the levels of inflammatory signal molecules; the apoptosis rate of macrophages; and the intracellular calcium concentration in erythrocytes in group B were higher than those in group A, followed by group C. These results suggest that TLR9 regulates ER stress in macrophages of mice with hemorrhagic shock through the TLR9-cGAS-STING-IFN signaling pathway. Increased expression of TLR9 enhanced macrophage activity, reduced apoptosis, enhanced inflammatory response and immune response, and restored electrolyte level, which might be a therapeutic option for the treatment of hemorrhagic shock.