Hemorrhagic Shock

Trauma-targeted delivery of tranexamic acid improves hemostasis and survival in rat liver hemorrhage model

BACKGROUND

Trauma-associated hemorrhage and coagulopathy remain leading causes of mortality. Such coagulopathy often leads to a hyperfibrinolytic phenotype where hemostatic clots become unstable because of upregulated tissue plasminogen activator (tPA) activity. Tranexamic acid (TXA), a synthetic inhibitor of tPA, has emerged as a promising drug to mitigate fibrinolysis. TXA is US Food and Drug Administration-approved for treating heavy menstrual and postpartum bleeding, and has shown promise in trauma treatment. However, emerging reports also implicate TXA for off-target systemic coagulopathy, thromboembolic complications, and neuropathy.

OBJECTIVE

We hypothesized that targeted delivery of TXA to traumatic injury site can enable its clot-stabilizing action site-selectively, to improve hemostasis and survival while avoiding off-target effects. To test this, we used liposomes as a model delivery vehicle, decorated their surface with a fibrinogen-mimetic peptide for anchorage to active platelets within trauma-associated clots, and encapsulated TXA within them.

METHODS

The TXA-loaded trauma-targeted nanovesicles (T-tNVs) were evaluated in vitro in rat blood, and then in vivo in a liver trauma model in rats. TXA-loaded control (untargeted) nanovesicles (TNVs), free TXA, or saline were studied as comparison groups.

RESULTS

Our studies show that in vitro, the T-tNVs could resist lysis in tPA-spiked rat blood. In vivo, T-tNVs maintained systemic safety, significantly reduced blood loss and improved survival in the rat liver hemorrhage model. Postmortem evaluation of excised tissue from euthanized rats confirmed systemic safety and trauma-targeted activity of the T-tNVs.

CONCLUSION

Overall, the studies establish the potential of targeted TXA delivery for safe injury site-selective enhancement and stabilization of hemostatic clots to improve survival in trauma.

Comparative analysis of isoform-specific and non-selective histone deacetylase inhibitors in attenuating the intestinal damage after hemorrhagic shock

BACKGROUND

Isoform-specific histone deacetylase inhibitors (HDACIs) MC1568 and ACY1083 are comparable to the non-selective HDACI valproic acid (VPA) in improving survival in rodents undergoing lethal hemorrhage. However, the organ-specific properties of isoform-specific HDACIs have not been fully evaluated. Also, whether they can act synergistically is not known. We hypothesized that isoform-specific HDACIs are superior to VPA in attenuating intestinal injury and act synergistically when coadministered.

METHODS

Sprague Dawley rats were hemorrhaged (40% of total blood volume) and randomized to receive (n=4 per group) (1) MC1568 (5 mg/kg), (2) ACY1083 (30 mg/kg), (3) MC1568+ACY1083 (combination: 5 mg/kg + 30 mg/kg, respectively), (4) VPA (250 mg/kg), or (5) normal saline (NS; vehicle; 250 μL). Animals were observed for 3 hours, after which blood samples were collected and samples of the ileum were harvested. Expression of interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and cytokine-induced neutrophil chemoattractant 1 (CINC-1) was assessed in the tissues using enzyme-linked immunosorbent assay. Intestinal cleaved caspase 3 (c-caspase 3) levels were assessed as a marker of apoptosis, and histologic sections of the ileum were examined for signs of bowel injury. Levels of IL-1β and TNF-α were also measured in the serum as global markers of inflammation.

RESULTS

Treatments with MC1568, ACY1083, MC1568+ACY1083, and VPA were associated with decreased IL-1β levels in the intestine and serum compared with NS. IL-1β and TNF-α levels were significantly lower in the ACY1083 group compared with the VPA group. CINC-1 levels were significantly lower in the isoform-specific HDACI groups compared with the NS; however, no significant differences were seen with VPA. All treatment groups had a lower expression of intestinal c-caspase 3 compared with NS. Furthermore, MC1568 and ACY1083 groups had lower apoptosis compared with the VPA group. Bowel injury scores were significantly lower in the isoform-specific HDACI groups compared with the NS group; however, the attenuation in the VPA-treated animals did not reach statistical significance.

DISCUSSION

Isoform-specific HDACIs provide superior intestinal protection compared with VPA in a rodent model of hemorrhagic shock.

LEVEL OF EVIDENCE

Preclinical study.

Protective Effect of Phosphatidylserine Blockade in Hemorrhagic Shock

BACKGROUND

Phosphatidylserine (PS) is a key cell membrane phospholipid normally maintained on the inner cell surface but externalizes to the outer surface in response to cellular stress. We hypothesized that PS exposure mediates organ dysfunction in hemorrhagic shock. Our aims were to evaluate PS blockade on (1) pulmonary, (2) renal, and (3) gut function, as well as (4) serum lysophosphatidic acid (LPA), an inflammatory mediator generated by PS externalization, as a possible mechanism mediating organ dysfunction.

MATERIALS AND METHODS

Rats were either (1) monitored for 130 min (controls, n = 3), (2) hemorrhaged then resuscitated (hemorrhage only group, n = 3), or (3) treated with Diannexin (DA), a PS blocking agent, followed by hemorrhage and resuscitation (DA + hemorrhage group, n = 4). Pulmonary dysfunction was assessed by arterial partial pressure of oxygen, renal dysfunction by serum creatinine, and gut dysfunction by mesenteric endothelial permeability (L_P). LPA levels were measured in all groups.

RESULTS

Pulmonary: there was no difference in arterial partial pressure of oxygen between groups. Renal: after resuscitation, creatinine levels were lower after PS blockade with DA versus hemorrhage only group (P = 0.01). Gut: L_P was decreased after PS blockade with DA versus hemorrhage only group (P < 0.01). Finally, LPA levels were also lower after PS blockade with DA versus the hemorrhage only group but higher than the control group (P < 0.01).

CONCLUSIONS

PS blockade with DA decreased renal and gut dysfunction associated with hemorrhagic shock and attenuated the magnitude of LPA generation. Our findings suggest potential for therapeutic targets in the future that could prevent organ dysfunction associated with hemorrhagic shock.

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.

Histone H4 induces platelet ballooning and microparticle release during trauma hemorrhage

Membrane ballooning is a fundamental mechanism by which platelets contribute to thrombin generation. However, this process has not previously been described in human disease. In this study, we demonstrated the presence of ballooning procoagulant platelets free in the circulation of critically injured humans, a phenomenon which results in systemic generation of thrombin and contributes to an acute coagulopathy. The surfaces of ballooning platelets were decorated with the damage-associated molecular pattern histone H4, and exposure of healthy platelets to histone caused membrane disruption and recapitulated the phenotypic changes in injured patients. These findings provide a description of platelet ballooning contributing to human disease and identify histone release from injured tissues as a driver of the procoagulant ballooning process.

Trauma hemorrhage is a leading cause of death and disability worldwide. Platelets are fundamental to primary hemostasis, but become profoundly dysfunctional in critically injured patients by an unknown mechanism, contributing to an acute coagulopathy which exacerbates bleeding and increases mortality. The objective of this study was to elucidate the mechanism of platelet dysfunction in critically injured patients. We found that circulating platelets are transformed into procoagulant balloons within minutes of injury, accompanied by the release of large numbers of activated microparticles which coat leukocytes. Ballooning platelets were decorated with histone H4, a damage-associated molecular pattern released in massive quantities after severe injury, and exposure of healthy platelets to histone H4 recapitulated the changes in platelet structure and function observed in trauma patients. This is a report of platelet ballooning in human disease and of a previously unrecognized mechanism by which platelets contribute to the innate response to tissue damage.

Pathophysiological significance of clock genes BMAL1 and PER2 as erythropoietin-controlling factors in acute blood hemorrhage

This study aimed to characterize the pathophysiology, including possible correlations, of clock gene expression and erythropoietin (EPO) production in the acute stage of blood hemorrhage. Specimens of human cortical tissues (right and left kidneys) and cardiac blood were collected at autopsy from 52 cases following mortality due to acute-stage blood hemorrhage following sharp instrument injury. BMAL1 and PER2 mRNA levels were determined by reverse transcription-polymerase chain reaction; BMAL1 and PER2 protein levels were assessed using immunohistochemistry; BMAL1 protein levels were quantitatively measured by western blotting; and serum EPO levels were measured by chemiluminescent enzyme immunoassay. Separately, a rat model of hemorrhagic conditions was generated and used to confirm the results obtained with autopsy-derived specimens. A positive correlation was observed between BMAL1 protein and serum EPO levels, but not between BMAL1 mRNA levels and serum EPO levels. We also noted that Per2 mRNA expression became elevated in humans who survived for > 3 h after acute hemorrhagic events, with subsequent decreases in serum EPO levels. The rat model showed that even short (30-min) intervals of blood loss yielded increases in both Bmal1 mRNA and serum EPO levels; longer (60-min) intervals resulted in increases in Per2 mRNA expression along with decreases in serum EPO. Thus, the acute-stage human hemorrhage cases and the rat hemorrhage model yielded similar tendencies for clock gene expression and EPO secretion. In conclusion, our results indicated that clock genes are involved in the regulation of EPO production during the early stages of hypoxia/ischemia resulting from the acute hemorrhagic events.

Extracellular CIRP (eCIRP) and inflammation

Cold-inducible RNA-binding protein (CIRP) was discovered 2 decades ago while studying the mechanism of cold stress adaptation in mammals. Since then, the role of intracellular CIRP (iCIRP) as a stress-response protein has been extensively studied. Recently, extracellular CIRP (eCIRP) was discovered to also have an important role, acting as a damage-associated molecular pattern, raising critical implications for the pathobiology of inflammatory diseases. During hemorrhagic shock and sepsis, inflammation triggers the translocation of CIRP from the nucleus to the cytosol and its release to the extracellular space. eCIRP then induces inflammatory responses in macrophages, neutrophils, lymphocytes, and dendritic cells. eCIRP also induces endoplasmic reticulum stress and pyroptosis in endothelial cells by activating the NF-κB and inflammasome pathways, and necroptosis in macrophages via mitochondrial DNA damage. eCIRP works through the TLR4-MD2 receptors. Studies with CIRP-/- mice reveal protection against inflammation, implicating eCIRP to be a novel drug target. Anti-CIRP Ab or CIRP-derived small peptide may have effective therapeutic potentials in sepsis, acute lung injury, and organ ischemia/reperfusion injuries. The current review focuses on the pathobiology of eCIRP by emphasizing on signal transduction machineries, leading to discovering novel therapeutic interventions targeting eCIRP in various inflammatory diseases.

Associations between changes in precerebral blood flow and cerebral oximetry in the lower body negative pressure model of hypovolemia in healthy volunteers

Reductions in cerebral oxygen saturation (ScO₂) measured by near infra-red spectroscopy have been found during compensated hypovolemia in the lower body negative pressure (LBNP)-model, which may reflect reduced cerebral blood flow. However, ScO₂ may also be contaminated from extracranial (scalp) tissues, mainly supplied by the external carotid artery (ECA), and it is possible that a ScO₂ reduction during hypovolemia is caused by reduced scalp, and not cerebral, blood flow. The aim of the present study was to explore the associations between blood flow in precerebral arteries and ScO₂ during LBNP-induced hypovolemia. Twenty healthy volunteers were exposed to LBNP 20, 40, 60 and 80 mmHg. Blood flow in the internal carotid artery (ICA), ECA and vertebral artery (VA) was measured by Doppler ultrasound. Stroke volume for calculating cardiac output was measured by suprasternal Doppler. Associations of changes within subjects were examined using linear mixed-effects regression models. LBNP reduced cardiac output, ScO₂ and ICA and ECA blood flow. Changes in flow in both ICA and ECA were associated with changes in ScO₂ and cardiac output. Flow in the VA did not change during LBNP and changes in VA flow were not associated with changes in ScO₂ or cardiac output. During experimental compensated hypovolemia in healthy, conscious subjects, a reduced ScO₂ may thus reflect a reduction in both cerebral and extracranial blood flow.

Trauma-induced coagulopathy: The past, present, and future

Trauma remains a leading cause of death worldwide, and most early preventable deaths in both the civilian and military settings are due to uncontrolled hemorrhage, despite paradigm advances in modern trauma care. Combined tissue injury and shock result in hemostatic failure, which has been identified as a multidimensional molecular, physiologic and clinical disorder termed trauma-induced coagulopathy (TIC). Understanding the biology of TIC is of utmost importance, as it is often responsible for uncontrolled bleeding, organ failure, thromboembolic complications, and death. Investigations have shown that TIC is characterized by multiple phenotypes of impaired hemostasis due to altered biology in clot formation and breakdown. These coagulopathies are attributable to tissue injury and shock, and encompass underlying endothelial, immune and inflammatory perturbations. Despite the recognition and identification of multiple mechanisms and mediators of TIC, and the development of targeted treatments, the mortality rates and associated morbidities due to hemorrhage after injury remain high. The purpose of this review is to examine the past and present understanding of the multiple distinct but highly integrated pathways implicated in TIC, in order to highlight the current knowledge gaps and future needs in this evolving field, with the aim of reducing morbidity and mortality after injury.

Practical approaches to managing postpartum haemorrhage with limited resources

Mortality from postpartum haemorrhage (PPH) is higher in low resource settings due to increased incidence, higher case fatality rates and poor general health of the population. The challenges of managing PPH with limited resources are presented. Feasible interventions for preventing and treating PPH for home births are described. Given that maternity care is organised around levels of care in low resource settings, guidance is provided for what measures can be performed to manage PPH at different levels of care (clinic, community health centre, district hospital, regional and central hospital); and by which cadre (midwife, clinical officer, general doctor, specialist). Effective management of PPH requires on-going training and emergency drills. Reducing mortality from PPH is not possible without available urgent transport from home to facility and between levels of care. In addition, the essential building blocks of the health system must be functional to enable effective management of PPH.

Outcomes following trauma laparotomy for hypotensive trauma patients: A UK military and civilian perspective

BACKGROUND

The management of trauma patients has changed radically in the last decade, and studies have shown overall improvements in survival. However, reduction in mortality for the many may obscure a lack of progress in some high-risk patients. We sought to examine the outcomes for hypotensive patients requiring laparotomy in UK military and civilian cohorts.

METHODS

We undertook a review of two prospectively maintained trauma databases: the UK Joint Theatre Trauma Registry for the military cohort (February 4, 2003, to September 21, 2014) and the trauma registry of the Royal London Hospital major trauma center (January 1, 2012, to January 1, 2017) for civilian patients. Adults undergoing trauma laparotomy within 90 minutes of arrival at the emergency department (ED) were included.

RESULTS

Hypotension was present on arrival at the ED in 155 (20.4%) of 761 military patients. Mortality was higher in hypotensive casualties (25.8% vs. 9.7% in normotensive casualties; p < 0.001). Hypotension was present on arrival at the ED in 63 (35.7%) of 176 civilian patients. Mortality was higher in hypotensive patients (47.6% vs. 12.4% in normotensive patients; p < 0.001). In both cohorts of hypotensive patients, neither the average injury severity, the prehospital time, the ED arrival systolic blood pressure, nor mortality rate changed significantly during the study period.

CONCLUSIONS

Despite improvements in survival after trauma for patients overall, the mortality for patients undergoing laparotomy who arrive at the ED with hypotension has not changed and appears stubbornly resistant to all efforts. Specific enquiry and research should continue to be directed at this high-risk group of patients.

LEVEL OF EVIDENCE

Prognostic/Epidemiologic, level IV.

A US military Role 2 forward surgical team database study of combat mortality in Afghanistan

BACKGROUND

Timely and optimal care can reduce mortality among critically injured combat casualties. US military Role 2 surgical teams were deployed to forward positions in Afghanistan on behalf of the battlefield trauma system. They received prehospital casualties, provided early damage control resuscitation and surgery, and rapidly transferred casualties to Role 3 hospitals for definitive care. A database was developed to capture Role 2 data.

METHODS

A retrospective review and descriptive analysis were conducted of battle-injured casualties transported to US Role 2 surgical facilities in Afghanistan from February 2008 to September 2014. Casualties were analyzed by mortality status and location of death (pretransport, intratransport, or posttransport), military affiliation, transport time, injury type and mechanism, combat mortality index-prehospital (CMI-PH), and documented prehospital treatment.

RESULTS

Of 9,557 casualties (median age, 25.0 years; male, 97.4%), most (95.1%) survived to transfer from Role 2 facility care. Military affiliation included US coalition forces (37.4%), Afghanistan National Security Forces (23.8%), civilian/other forces (21.3%), Afghanistan National Police (13.5%), and non-US coalition forces (4.0%). Mortality differed by military affiliation (p < 0.001). Among fatalities, most were Afghanistan National Security Forces (30.5%) civilian/other forces (26.0%), or US coalition forces (25.2%). Of those categorized by CMI-PH, 40.0% of critical, 11.2% of severe, 0.8% of moderate, and less than 0.1% of mild casualties died. Most fatalities with CMI-PH were categorized as critical (66.3%) or severe (25.9%), whereas most who lived were mild (56.9%) or moderate (25.4%). Of all fatalities, 14.0% died prehospital (pretransport, 5.8%; intratransport, 8.2%), and 86.0% died at a Role 2 facility (posttransport). Of fatalities with documented transport times (median, 53.0 minutes), most (61.7%) were evacuated within 60 minutes.

CONCLUSIONS

Role 2 surgical team care has been an important early component of the battlefield trauma system in Afghanistan. Combat casualty care must be documented, collected, and analyzed for outcomes and trends to improve performance.

LEVEL OF EVIDENCE

Therapeutic/Care Management, level IV.

The evolution of pediatric transfusion practice during combat operations 2001-2013

BACKGROUND

Hemostatic resuscitation principles have significantly changed adult trauma resuscitation over the past decade. Practice patterns in pediatric resuscitation likely have changed as well; however, this evolution has not been quantified. We evaluated pediatric resuscitation practices over time within a combat trauma system.

METHODS

The Department of Defense Trauma Registry was queried from 2001 to 2013 for pediatric patients (<18 years). Patients with burns, drowning, and missing injury severity score were excluded. Volumes of crystalloid, packed red blood cells (PRBC), whole blood, plasma, and platelets (PLT) given in the first 24 hours were calculated per kilogram body weight. Tranexamic acid use was also determined. Patients were divided into Early (2001-2005) and Late (2006-2013) cohorts, and subgroups of transfused (TX+) and massively transfused (MT+) patients were created. Intensive care unit and hospital length of stay and 24-hour and in-hospital mortality rates were compared.

RESULTS

A total of 4,358 patients met inclusion criteria. Comparing Early versus Late, injuries from explosions, isolated or predominant head injuries, and injury severity score all increased. The proportion of TX+ patients also increased significantly (13.6% vs 37.4%, p < 0.001) as did the number of MT+ patients (2.1% vs 15.5%, p < 0.001). Transfusion of high plasma:RBC and PLT:RBC ratios increased in both the TX+ and MT+ subgroups, although overall, PLT and whole blood use was low. After adjusting for differences between groups, the odds of death was no different Early versus Late but decreased significantly in the MT+ patients with time as a continuous variable.

CONCLUSION

Transfusion practice in pediatric combat casualty care shifted toward a more hemostatic approach over time. All-cause mortality was low and remained stable overall and even decreased in MT+ patients despite more injuries due to explosions, more head injuries, and greater injury severity. However, further study is required to determine the optimal resuscitation practices in critically injured children.

LEVEL OF EVIDENCE

Epidemiologic study, level IV.

A Quantitative Study of the Dimensional Change of Inferior Vena Cava on Computed Tomography During Acute Hemorrhage Shock in Swine

Background: The purpose of this study was to examine the dimensional change of IVC during acute hemorrhage through a volume-controlled acute hemorrhagic shock model in swine. Methods: Volume-controlled hemorrhage was performed in 10 adult Bama mini pigs. Enhanced CT scan and hemodynamic monitoring were performed when the cumulative blood loss volume reached 0%, 10%, 20%, 30%, and 40%. The transverse diameter (T) and anteroposterior diameter (AP) of IVC were measured in axial images. Hemodynamic parameters were obtained with Pulse Contour Cardiac Output (PiCCO) hemodynamic monitor device. Arterial blood samples were also collected for artery blood gas analysis at each time point. Results: As the blood loss volume increased, the collapsibility (T/AP) and cross section area (CSA) of IVC significantly changed first in hepatic level and pre-renal level. The significant decrease of the CSA of IVC (shrink) occurred early when the blood loss volume reached only 10%, but the collapse of IVC occurred until the blood loss volume reached 30%. Conclusions: IVC shrank early but collapsed late during the acute hemorrhage in swine. The finding of collapsed IVC on CT scans suggested severe hypovolemic shock. Evaluation of the IVC at the CT scans can be an adjunctive test of the hemodynamic status in trauma patients.

Platelet count as a new biomarker for acute kidney injury induced by hemorrhagic shock

The aim of this study was to investigate the association between nadir platelet count and acute kidney injury (AKI) or 28-day all-cause mortality induced by hemorrhagic shock (HS), and to determine the cutoff value of nadir platelet count in HS clinical practice. This retrospective study included hospitalized patients enrolled in a tertiary-care teaching hospital from January 1, 2010 to December 31, 2015. Clinical data from HS admitted to the intensive care unit (ICU) were evaluated. Nadir platelet count was defined as the lowest values in the first 48 h. Multivariate logistic regression and Cox proportional hazards regression were used to assess the correlation between nadir platelet count and AKI or 28-day all-cause mortality induced by HS, respectively; the area under receiver operating characteristic (AU-ROC) and Youde's index were used to determine the optimal cutoff value of nadir platelet count. Kaplan-Meier's method and log-rank test were assessed for the 28-day all-cause mortality in AKI and non-AKI groups. Of 1589 patients screened, 84 patients (mean age,37.1 years; 58 males) were included in the primary analysis in which 30 patients with AKI. Multiple logistic results indicated that nadir platelet count was a risk factor of AKI (OR = 0.71,95% confidence interval [CI] 0.54-0.93, P < 0.05). Cox regression analysis revealed that nadir platelet count was independent risk factors for 28-day all-cause mortality (Hazard ratios [HR]0.89,95%CI 0.76-0.99, P < 0.05). Kaplan-Meier curve showed that 28-day all-cause mortality was significantly higher in patients with AKI than non-AKI (P < 0.001).These results suggest that nadir platelet count in the first 48 h is a new biomarker for AKI and 28-day all-cause mortality induced by HS. Moreover, the risk for AKI and 28-day all-cause mortality in HS patients decreased by 29% and 11%, respectively, for every 10 × 10⁹/L increase in platelet count. Additional studies are needed to investigate whether elevation of nadir platelet count reduces the risk in different genders.

Exogenous ghrelin ameliorates acute lung injury by modulating the nuclear factor κB inhibitor kinase/nuclear factor κB inhibitor/nuclear factor κB pathway after hemorrhagic shock

Previous studies have shown that ghrelin, a peptide produced in the stomach, attenuates acute lung injury (ALI) in various animal models, and that some of these effects are associated with inhibition of the nuclear factor κB signaling pathway. This study investigated whether ghrelin exerts beneficial effects on hemorrhagic shock (HS)-induced ALI by modulating nuclear factor κB inhibitor kinase/nuclear factor κB inhibitor/nuclear factor κB (IKK/IκBα/NF-κB) pathway activity. HS was induced in male SD rats by withdrawing blood to a mean arterial pressure (MAP) of 40 mm Hg for 1 h; rats then received ghrelin (10 nmol/kg) or vehicle intravenously and were resuscitated with the shed blood and an equal volume of Ringer lactate solution followed by observation for 2 h. After resuscitation, samples were collected and analyzed for lung histopathology, wet to dry weight ratio (W/D), bronchoalveolar lavage fluid (BALF) protein, neutrophil infiltration, plasma inflammatory cytokines (TNF-α and IL-6), and cytoplasmic phosphorylated IKKβ, IκBα, phosphorylated IκBα and nuclear NF-κB expression. Compared to those in the two sham groups, lung injury, W/D, BALF protein, neutrophil infiltration, plasma TNF-α and IL-6 levels, and IKK/IκBα/NF-κB pathway activation were significantly increased in HS rats. After ghrelin administration, all parameters analyzed were decreased compared to those without ghrelin in HS rats. Moreover, ghrelin alleviated the decreased MAP after resuscitation compared to that in HS rats. Exogenous ghrelin attenuates the inflammatory response and acute lung injury after HS. These beneficial effects appear to be mediated through inhibition of IKK/IκBα/NF-κB signaling.

Metabolomics analysis of gut barrier dysfunction in a trauma-hemorrhagic shock rat model

Intestinal barrier dysfunction has been implicated in the development of multiorgan dysfunction syndrome caused by the trauma-hemorrhagic shock (THS). However, the mechanisms underlying THS-induced gut barrier injury are still poorly understood. In the present study, we used the metabolomics analysis to test the hypothesis that altered metabolites might be related to the development of THS-induced barrier dysfunction in the large intestine. Under the induction of THS, gut barrier failure was characterized by injury of permeability and mucus layer, which were companied by the decreased expression of zonula occludens-1 in the colon and increased levels of inflammatory factors including tumor necrosis factor-α, interferon-γ, interleukin (IL)-6, and IL-1β in the serum. A total of 16 differential metabolites were identified in colonic tissues from THS-treated rats compared with control rats. These altered metabolites included dihydroxy acetone phosphate, ribose-5-phosphate, fructose, glyceric acid, succinic acid, and adenosine, which are critical intermediates or end products that are involved in pentose phosphate pathway, glycolysis, and tricarboxylic acid cycle as well as mitochondrial adenosine triphosphate biosynthesis. These findings may offer important insight into the metabolic alterations in THS-treated gut injury, which will be helpful for developing effective metabolites-based strategies to prevent THS-induced gut barrier dysfunction.

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.

Quality Management of massive transfusion protocol incorporating tranexamic acid adherence

Massive transfusion protocols (MTP) vary at different institutions. We implemented an algorithm in the transfusion service to support our Level I trauma center in 2007 and periodically monitor MTP utilization as part of ongoing quality management. At the last review in 2013, median plasma: RBC ratio was 1:1.8. We undertook a retrospective 3-year review of MTP activations stratifying by trauma versus non-trauma indications, and blood component utilization of the massive transfusion (MT) cases, adding a review of tranexamic acid (TXA) administration to the audit. The median transfused plasma: RBC ratio was 1:1.9 in trauma MT, and 1:1.6 in the non-trauma MT cases. Non-trauma MT patients at our institution were significantly older and more coagulopathic at MTP initiation compared to trauma MT patients, received fewer RBC units (15.5 versus 20.2), and had higher mortality. TXA adherence increased over the 3-year period to 60% of all trauma MTP activations in 2017.

Intravenous Vitamin C attenuates hemorrhagic shock-related renal injury through the induction of SIRT1 in rats

To investigate the effect of intravenous Vitamin C (VC) on hemorrhagic shock (HS)-associated rat renal injury and the involved mechanism. Thirty SD rats were randomly assigned to the sham surgery (sham), hemorrhagic shock (HS), HS+100 mg/kg VC (H + VL), HS+500 mg/kg VC (H + VH) and HS+100 mg/kg VC + EX527 (H + VL + E) groups. Tissue and blood samples were collected 6 h after surgery. Kidney pathological changes were scored. Creatinine (CRE), blood urea nitrogen (BUN), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) levels in serum and Vitamin C levels and superoxide dismutase (SOD) activity and the ability to suppress hydroxyl radical (RAFHR) in plasma were measured. The expression of Sirtuin1 (SIRT1), Acetyl-NF-κB (Ace-NF-κB), heme oxygenase-1 (HO-1), TNF-α, and IL-1β in tissues was analyzed by ELISA or western-blot. In the HS group, the kidney pathological score and CRE, BUN, TNF-α, and IL-1β levels in serum were significantly higher than in the Sham group (P < 0.05), while SOD and RAFHR were significantly decreased in the plasma (P < 0.05). SOD activity and SIRT1 expression were remarkably lower in the kidney in the HS group than in the Sham group (P < 0.05), while MDA, TNF-α, and IL-1β concentrations and Acetyl-NF-κB andHO-1 expression in the kidney showed a noteworthy increase compared to the Sham group (P < 0.05). Compared to the HS group, VC treatment led to a remarkable reduction in the kidney pathological score and CRE,BUN,TNF-α, and IL-1β levels (P < 0.05), and a significant increase in Vitamin C, SOD, and RAFHR levels in the plasma (P < 0.05). Additionally, MDA, TNF-α, IL-1β and Acetyl-NF-κB expression levels were decreased in the kidney (P < 0.05), while SOD, SIRT1 and HO-1 levels were notably enhanced. There were no differences between the H + VL and H + VH groups aside from plasma Vitamin C levels. The effect of Vitamin C was decreased after the addition of EX527, which inhibits SIRT1. Intravenous Vitamin C might attenuate HS-related renal injury via the SIRT1 pathway, and it appears that there were no differences in the effects between the high and low doses.

Two-wavelength oximetry of tissue microcirculation based on sidestream dark-field imaging

Monitoring oxygen saturation (SO2) in microcirculation is effective for understanding disease dynamics. We have developed an SO2 estimation method, sidestream dark-field (SDF) oximetry, based on SDF imaging. SDF imaging is a noninvasive and clinically applicable technique to observe microcirculation. We report the first in vivo experiment observing the changes in SO2 of microcirculation using SDF oximetry. First, heat from the light-emitting diodes used for the SDF imaging might affect hemodynamics in microcirculation, hence, we performed an experiment to evaluate the influence of that on the SDF oximetry. The result suggested that SDF oximetry had enough stability for long-term experiments. Then, to evaluate the sensitivity of SDF oximetry to alterations in the hemodynamics of the microcirculation, we observed the time-lapsed SO2 changes in the dermis microcirculation of rats under hypoxic stimulation. We confirmed that the SO2 estimated by SDF oximetry was in accordance with changes in the fraction of inspired oxygen (FiO2). Thus, SDF oximetry is considered to be able to observe SO2 changes that occur in accordance with alteration of the microcirculation.

Complication patterns in patients undergoing venoarterial extracorporeal membrane oxygenation in intensive care unit: Multiple correspondence analysis and hierarchical ascendant classification

Background

Treatment by venoarterial extracorporeal membrane oxygenation (VA-ECMO) is widely used today, even though it is associated with high risks of complications and death. While studies have focused on the relationship between some of these complications and the risk of death, the relationship between different complications has never been specifically examined, despite the fact that the occurrence of one complication is known to favor the occurrence of others. Our objective was to describe the relationship between complications in patients undergoing VA-ECMO in intensive care unit (ICU) and to identify, if possible, patterns of patients according to complications.

Methods and findings

As part of a retrospective cohort study, we conducted a multiple correspondence analysis followed by a hierarchical ascendant classification in order to identify patterns of patients according to main complications (sepsis, thromboembolic event, major transfusion, major bleeding, renal replacement therapy) and in-ICU death. Our cohort of 145 patients presented an in-ICU mortality rate of 50.3%. Morbidity was high, with 36.5% of patients presenting three or more of the five complications studied. Multiple correspondence analysis revealed a cumulative inertia of 76.9% for the first three dimensions. Complications were clustered together and clustered close to death, prompting the identification of four patterns of patients according to complications, including one with no complications.

Conclusions

Our study, based on a large cohort of patients undergoing VA-ECMO in ICU and presenting a mortality rate comparable to that reported in the literature, identified numerous and often interrelated complications. Multiple correspondence analysis and hierarchical ascendant classification yielded clusters of patients and highlighted specific links between some of the complications studied. Further research should be conducted in this area.

Role of metabolic changes of mucosal layer in the intestinal barrier dysfunction following trauma/hemorrhagic shock

BACKGROUND

The mucosal layer plays an important role in regulating the intestinal barrier function. However, the underlying mechanisms of intestinal barrier dysfunction caused by trauma-hemorrhagic shock (THS) are still unknown.

METHODS

In this study, we examined the barrier damages, inflammatory responses as well as the metabolic changes of the mucosal layer of the colon in a THS rat model.

RESULTS

The results showed that compared to the rats treated with trauma only, THS induced marked failure of intestinal barrier characterized by increased intestinal permeability, inflammatory cell infiltration and decreased expression of genes involved in epithelial integrity. Moreover, decreased colonic mucus content and goblet cell numbers indicated that the mucosal layer was also impaired in response to THS. This was companied by the anomalous inflammatory responses in the tissue. Finally, microdialysis catheter examination showed that metabolites including glycerol, glucose, lactate and pyruvate, glutamate and glutamine were also altered by THS.

CONCLUSION

Our results provide evidence that mucus layer-associated metabolic changes may contribute to the THS-induced intestinal barrier dysfunction.

New insights into the pathophysiology of postoperative hemorrhage in thyroid surgery: An experimental study in a porcine model

BACKGROUND

Postoperative cervical hemorrhage is a rare but life-threatening complication that can cause severe morbidity. Different mechanisms leading to asphyxia have been described based only on clinical observation.

METHODS

We performed a series of in vivo animal studies simulating post-thyroidectomy hemorrhage and its effect on respiratory drive. Three series of tests were carried out in 12 German domestic pigs under general anesthesia. The pigs were breathing spontaneously with secured airways. An additional series using functional magnetic resonance imaging of the pigs' brainstem was also conducted.

RESULTS

The first experimental series carried out on 2 animals revealed an obvious difference between the effects of cervical hemorrhage and external bleeding with development of hemorrhagic shock. An experimental setting for the repeated simulation of cervical hemorrhage was established. A pressure-dependent mechanism was discovered that led to apnea in every animal despite the secured airway. In 8 of 10 animals, relief of cervical pressure led to complete respiratory recovery. The test was repeated up to 6 times per pig. Apnea was induced in 25 of 25 test procedures (100%) and was followed by respiratory recovery in 22 of 25 tests (88%). The threshold pressure at which the respiratory rate started to decrease was 47 ± 14 Torr when blood was used to increase the cervical compartment pressure. When silicone oil was used in a further experimental series, the threshold pressure was similar at 44 ± 21 Torr. The cervical compartment pressure needed to induce apnea was 74 ± 18 Torr using blood and 74 ± 39 Torr using silicone oil, both of which exceeded the mean arterial pressure by 28 Torr during apnea. Functional magnetic resonance imaging revealed a decrease in brainstem activity during phases of increased cervical compartment pressure, which suggests a possible role for cerebral vascular perfusion.

CONCLUSION

Respiratory drive can be suppressed by increased pressure in the cervical compartment, possibly because of a pressure-dependent impairment in cerebral perfusion through a form of cervical compartment phenomenon or, less likely, a pressure-dependent reflex (nervous) mechanism.

Blood pressure variability, heart functionality, and left ventricular tissue alterations in a protocol of severe hemorrhagic shock and resuscitation

Autonomic control of blood pressure (BP) and heart rate (HR) is crucial during bleeding and hemorrhagic shock (HS) to compensate for hypotension and hypoxia. Previous works have observed that at the point of hemodynamic decompensation a marked suppression of BP and HR variability occurs, leading to irreversible shock. We hypothesized that recovery of the autonomic control may be decisive for effective resuscitation, along with restoration of mean BP. We computed cardiovascular indexes of baroreflex sensitivity and BP and HR variability by analyzing hemodynamic recordings collected from five pigs during a protocol of severe hemorrhage and resuscitation; three pigs were sham-treated controls. Moreover, we assessed the effects of severe hemorrhage on heart functionality by integrating the hemodynamic findings with measures of plasma high-sensitivity cardiac troponin T and metabolite concentrations in left ventricular (LV) tissue. Resuscitation was performed with fluids and norepinephrine and then by reinfusion of shed blood. After first resuscitation, mean BP reached the target value, but cardiovascular indexes were not fully restored, hinting at a partial recovery of the autonomic mechanisms. Moreover, cardiac troponins were still elevated, suggesting a persistent myocardial sufferance. After blood reinfusion all the indexes returned to baseline. In the harvested heart, LV metabolic profile confirmed the acute stress condition sensed by the cardiomyocytes. Variability indexes and baroreflex trends can be valuable tools to evaluate the severity of HS, and they may represent a more useful end point for resuscitation in combination with standard measures such as mean values and biological measures.

NEW & NOTEWORTHY Autonomic control of blood pressure was highly impaired during hemorrhagic shock, and it was not completely recovered after resuscitation despite global restoration of mean pressures. Moreover, a persistent myocardial sufferance emerged from measured cardiac troponin T and metabolite concentrations of left ventricular tissue. We highlight the importance of combining global mean values and biological markers with measures of variability and autonomic control for a better characterization of the effectiveness of the resuscitation strategy.

The Chemistry of Lyophilized Blood Products

With the development of new biologics and bioconjugates, storage and preservation have become more critical than ever before. Lyophilization is a method of cell and protein preservation by removing a solvent such as water from a substance followed by freezing. This technique has been used in the past and still holds promise for overcoming logistic challenges in safety net hospitals with limited blood banking resources, austere environments such as combat, and mass casualty situations where existing resources may be outstripped. This method allows for long-term storage and transport but requires the bioconjugation of preservatives to prevent cell destabilization. Trehalose is utilized as a bioconjugate in platelet and red blood cell preservation to maintain protein thermodynamics and stabilizing protein formulations in liquid and freeze-dried states. Biomimetic approaches have been explored as alternatives to cryo- and lyopreservation of blood components. Intravascular hemostats such as PLGA nanoparticles functionalized with PEG motifs, topical hemostats utilizing fibrinogen or chitosan, and liposomal encapsulated hemoglobin with surface modifications are effectively stored long-term through bioconjugation. In thinking about the best methods for storage and transport, we are focusing this topical review on blood products that have the longest track record of preservation and looking at how these methods can be applied to synthetic systems.

A global perspective on vasoactive agents in shock

PURPOSE

We set out to summarize the current knowledge on vasoactive drugs and their use in the management of shock to inform physicians' practices.

METHODS

This is a narrative review by a multidisciplinary, multinational-from six continents-panel of experts including physicians, a pharmacist, trialists, and scientists.

RESULTS AND CONCLUSIONS

Vasoactive drugs are an essential part of shock management. Catecholamines are the most commonly used vasoactive agents in the intensive care unit, and among them norepinephrine is the first-line therapy in most clinical conditions. Inotropes are indicated when myocardial function is depressed and dobutamine remains the first-line therapy. Vasoactive drugs have a narrow therapeutic spectrum and expose the patients to potentially lethal complications. Thus, these agents require precise therapeutic targets, close monitoring with titration to the minimal efficacious dose and should be weaned as promptly as possible. Moreover, the use of vasoactive drugs in shock requires an individualized approach. Vasopressin and possibly angiotensin II may be useful owing to their norepinephrine-sparing effects.

Blood transfusion strategies for acute upper gastrointestinal bleeding: are we back where we started?

Blood transfusion practices for acute upper gastrointestinal hemorrhage have changed over time. Restrictive strategies, which gave way to more liberal approaches for the greater part of the 20^th century, have again gained traction as emerging research suggests restricting transfusion is associated with similar, or possibly better outcomes in UGI bleeding. In a large, retrospective cohort study from an integrated health care system in Taiwan, Chen, et al., report the association between early blood transfusion and clinical outcomes in patients presenting to the emergency department with UGI bleeding, and these findings are discussed in the context of current knowledge and practice.

The Role of Plasma Transfusion in Massive Bleeding: Protecting the Endothelial Glycocalyx?

Massive hemorrhage is a leading cause of death worldwide. During the last decade several retrospective and some prospective clinical studies have suggested a beneficial effect of early plasma-based resuscitation on survival in trauma patients. The underlying mechanisms are unknown but appear to involve the ability of plasma to preserve the endothelial glycocalyx. In this mini-review, we summarize current knowledge on glycocalyx structure and function, and present data describing the impact of hemorrhagic shock and resuscitation fluids on glycocalyx. Animal studies show that hemorrhagic shock leads to glycocalyx shedding, endothelial inflammatory changes, and vascular hyper-permeability. In these animal models, plasma administration preserves glycocalyx integrity and functions better than resuscitation with crystalloids or colloids. In addition, we briefly present data on the possible plasma components responsible for these effects. The endothelial glycocalyx is increasingly recognized as a critical component for the physiological vasculo-endothelial function, which is destroyed in hemorrhagic shock. Interventions for preserving an intact glycocalyx shall improve survival of trauma patients.

Evaluation of capillary leakage after vasopressin resuscitation in a hemorrhagic shock model

Background

Hemorrhagic shock (HS) is a major threat to patients with trauma and spontaneous bleeding. The aim of the study was to investigate early effects of vasopressin on metabolic and hemodynamic parameters and endothelium permeability by measuring capillary leakage compared to those of other resuscitation strategies in a HS model.

Methods

Forty-five Sprague-Dawley rats were randomized into five groups: S group (n = 5), sham-operated rats without shock or resuscitation; HS group (n = 10), HS and no resuscitation; RL group (n = 10), HS and resuscitation with Ringer’s lactate (RL); RLB group (n = 10), HS and resuscitation with two-third shed blood plus RL; and vasopressin group (n = 10), HS and resuscitation with RL, followed by continuous infusion of 0.04 U/kg/min vasopressin. The effects of resuscitation on hemodynamic parameters [mean arterial pressure (MAP), superior mesenteric artery blood flow (MBF), and mesenteric vascular resistances (MVR)], arterial blood gases, bicarbonate, base deficit, and lactate levels as well as on capillary leakage in the lung, ileum, and kidney were investigated. Capillary leakage was evaluated with Evans blue dye extravasation.

Results

In the vasopressin group, the MAP was higher than in the RL and RLB groups (p < 0.001), while MBF was decreased (p < 0.001). MVR were increased only in the vasopressin group (p < 0.001). Capillary leakage was increased in the lungs of the animals in the vasopressin group compared to that in the lungs of animals in the RLB group (p < 0.05); this increase was associated with the lowest partial pressure of oxygen (p < 0.05). Conversely, decreased capillary leakage was observed with vasopressin in the ileum (p < 0.05). Increased capillary leakage was observed in the kidney in the RLB and vasopressin groups (p < 0.05). Lastly, vasopressin use was associated with higher base deficit and lactate levels when compared to the RL and RLB groups (p < 0.001).

Conclusion

Although vasopressin was proposed as a vasoactive drug for provisional hemodynamic optimization in the early phase of HS resuscitation, the overall findings of this experimental study focus on the possible critical side effects of vasopressin on metabolic parameters and endothelium permeability.