Shock induced endotheliopathy (SHINE) in acute critical illness - a unifying pathophysiologic mechanism

Endothelial cell regulation of systemic haemodynamics and metabolism acts through the HIF transcription factors

BACKGROUND

The vascular endothelium has important endocrine and paracrine roles, particularly in the regulation of vascular tone and immune function, and it has been implicated in the pathophysiology of a range of cardiovascular and inflammatory conditions. This study uses a series of transgenic murine models to explore for the first time the role of the hypoxia-inducible factors, HIF-1α and HIF-2α in the pulmonary and systemic circulations as potential regulators of systemic vascular function in normoxic or hypoxic conditions and in response to inflammatory stress. We developed a series of transgenic mouse models, the HIF-1α Tie2Cre, deficient in HIF1-α in the systemic and pulmonary vascular endothelium and the L1Cre, a pulmonary endothelium specific knockout of HIF-1α or HIF-2α. In vivo, arterial blood pressure and metabolic activity were monitored continuously in normal atmospheric conditions and following an acute stimulus with hypoxia (10%) or lipopolysaccharide (LPS). Ex vivo, femoral artery reactivity was assessed using wire myography.

RESULTS

Under normoxia, the HIF-1α Tie2Cre mouse had increased systolic and diastolic arterial pressure compared to litter mate controls over the day-night cycle under normal environmental conditions. VO₂ and VCO₂ were also increased. Femoral arteries displayed impaired endothelial relaxation in response to acetylcholine mediated by a reduction in the nitric oxide dependent portion of the response. HIF-1α L1Cre mice displayed a similar pattern of increased systemic blood pressure, metabolic rate and impaired vascular relaxation without features of pulmonary hypertension, polycythaemia or renal dysfunction under normal conditions. In response to acute hypoxia, deficiency of HIF-1α was associated with faster resolution of hypoxia-induced haemodynamic and metabolic compromise. In addition, systemic haemodynamics were less compromised by LPS treatment.

CONCLUSIONS

These data show that deficiency of HIF-1α in the systemic or pulmonary endothelium is associated with increased systemic blood pressure and metabolic rate, a pattern that persists in both normoxic conditions and in response to acute stress with potential implications for our understanding of the pathophysiology of vascular dysfunction in acute and chronic disease.

Endothelial Dysfunction as a Component of Severe Acute Respiratory Syndrome Coronavirus 2-Related Multisystem Inflammatory Syndrome in Children With Shock

Supplemental Digital Content is available in the text.

NCT04420468.

Validation of the relationship between coagulopathy and localization of hydroxyethyl starch on the vascular endothelium in a rat hemodilution model

Various anticoagulant properties have been associated with hydroxyethyl starch (HES). However, the mechanism remains unclear and it has not been fully considered whether these properties are beyond the dilutional effect itself. The aim of this study was to reproduce the coagulopathy induced by HES and to test the hypothesis that the coagulopathy is caused by endothelial or glycocalyx damage due to localization of HES on the endothelium, which is caused by the high shear viscosity of dilutional blood. Using a rat model, we compared blood coagulability measured by Sonoclot, levels of endothelial and glycocalyx damage markers and coagulation factors, and blood shear viscosity when hemodilution was performed with physiological saline (PS), 6% HES 130/0.4 in PS, and 10% HES 200/0.5 in PS. We also evaluated the localization rates of fluorescently labeled HES on endothelium in the isolated aorta. HES decreased the fibrin gel formation rate more than did PS. HES was shown to cover the endothelium, possibly due to its high shear viscosity, and this mechanism potentially acted to protect, rather than damage, the endothelium and glycocalyx. However, this covering effect may be the cause of coagulopathy due to inhibition of von Willebrand factor secretion from the endothelium.

Fluid Therapy and the Microcirculation in Health and Critical Illness

Fluid selection and administration during shock is typically guided by consideration of macrovascular abnormalities and resuscitative targets (perfusion parameters, heart rate, blood pressure, cardiac output). However, the microcirculatory unit (comprised of arterioles, true capillaries, and venules) is vital for the effective delivery of oxygen and nutrients to cells and removal of waste products from the tissue beds. Given that the microcirculation is subject to both systemic and local control, there is potential for functional changes and impacts on tissue perfusion that are not reflected by macrocirculatory parameters. This chapter will present an overview of the structure, function and regulation of the microcirculation and endothelial surface layer in health and shock states such as trauma, hemorrhage and sepsis. This will set the stage for consideration of how these microcirculatory characteristics, and the potential disconnect between micro- and macrovascular perfusion, may affect decisions related to acute fluid therapy (fluid type, amount, and rate) and monitoring of resuscitative efforts. Available evidence for the impact of various fluids and resuscitative strategies on the microcirculation will also be reviewed.

Temporal profile of the pro- and anti-inflammatory responses to severe hemorrhage in patients with venous thromboembolism: Findings from the PROPPR trial

BACKGROUND

The Pragmatic Randomized Optimal Platelet and Plasma Ratios (PROPPR) trial showed that 15% of patients developed venous thromboembolism (VTE) following hemorrhage, but the mechanisms are unknown. Since inflammation is associated with hypercoagulability and thrombosis, our goal was to compare the temporal inflammatory profile following hemorrhagic shock in patients with and without VTE.

STUDY DESIGN

Secondary analysis was performed on data collected from PROPPR. Blood samples collected at 0 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours following admission were assayed on a 27-target cytokine panel, and compared between VTE (n = 83) and non-VTE (n = 475) patients. p < 0.05 indicated significance.

RESULTS

Over time, both groups exhibited elevations in proinflammatory mediators interleukin (IL)-6, IL-8, IL-10, granulocyte colony-stimulating factor 57, monocyte chemoattractant protein 1 and macrophage inflammatory protein 1β, and anti-inflammatory mediators IL-1ra and IL-10 (p < 0.05 vs. admission). Venous thromboembolism patients showed amplified responses for IL-6 (6-72 hours) and IL-8 (6-24 hours), which peaked at later time points, and granulocyte colony-stimulating factor 57 (12-24 hours), monocyte chemoattractant protein 1 (6-72 hours), and macrophage inflammatory protein-1 β (2-12 hours) (p < 0.05 vs. non-VTE per time point) that peaked at similar time points to non-VTE patients. The anti-inflammatory responses were similar between groups, but the interleukin-mediated proinflammatory responses continued to rise after the peak anti-inflammatory response in the VTE group. The occurrence rate of adverse events was higher in VTE (97%) versus non-VTE (87%, p = 0.009) and was associated with higher inflammation.

CONCLUSION

Patients with VTE following hemorrhagic shock exhibited a prolonged and amplified proinflammatory responses mediated by select interleukin, chemotactic, and glycoprotein cytokines that are not antagonized by anti-inflammatory mediators. This response is not related to randomization group, injury severity or degree of shock, but may be linked to adverse events.

LEVEL OF EVIDENCE

Prognostic, level III.

The effect of perturbations of the glycocalyx on microvascular perfusion in the obese trauma population: an in vitro study

Objectives

Patients with morbid obesity have impaired responses to resuscitation following severe injury, which may contribute to adverse outcomes. Obesity is associated with microvascular dysfunction and metabolic changes associated with altered hemorheological profiles. These include decreased red blood cell (RBC) deformity associated with increased aggregation and adhesion. These RBC changes may be impacted by the glycocalyx layer of the endothelial cell (EC) and RBC. Degradation of either or both glycocalyx layers may impair microvascular perfusion. This was studied from blood obtained from patients with obesity and in an in vitro microfluidic device to mimic the microvascular environment.

Methods

RBCs were obtained from fresh whole blood from normal controls and patients with obesity (body mass index 37.6–60.0). RBC glycocalyx was indexed by fluorescent intensity and shedding of EC glycocalyx components into the serum was determined by measurement of syndecan-1 and hyaluronic acid. In a second set of experiments, human umbilical vein endothelial cell monolayers (HUVEC) were perfused with RBC suspensions from control and patients with obesity using a microfluidic device and RBC adherence under normoxic or shock conditions (hypoxia+epinephrine) was determined using confocal microscopy. HUVEC glycocalyx thickness and shedding were also measured.

Results

Microfluidic studies demonstrated that RBC obtained from subjects with obesity had increased adhesion to the endothelial layer, which was more profound under shock conditions versus normal subjects. This appeared to be related to increased shedding of the endothelial glycocalyx following shock as well as a diminished RBC glycocalyx layer in the obese population.

Conclusion

Blood from patients with obesity have decreased RBC glycocalyx thickness accompanied by evidence of increased EC glycocalyx shedding. In vitro adhesion to the endothelium was more pronounced with RBC from patients with obesity and was significantly greater under ‘shock conditions’. Hemorheological properties of RBC from patients with obesity may account for failure of standard resuscitation procedures in the trauma patient.

Level of evidence

ABO blood types and sepsis mortality

Background

We aimed to determine if the ABO blood types carry different risks of 30-day mortality, acute kidney injury (AKI), and endothelial damage in critically ill patients with sepsis. This was a retrospective cohort study of three independent cohorts of critically ill patients from the United States and Scandinavia consisting of adults with septic shock. We compared the 30-day mortality across the blood types within each cohort and pooled the results in a meta-analysis. We also estimated the incidence of AKI and degree of endothelial damage, as measured by blood concentrations of soluble thrombomodulin and syndecan-1.

Results

We included 12,342 patients with severe sepsis. In a pooled analysis blood type B carried a slightly lower risk of 30-day all-cause mortality compared to non-blood type B (adjusted HR 0.88; 95%-CI 0.79–0.98; p = 0.02). There was no difference in the risk of AKI. Soluble thrombomodulin and syndecan-1 concentrations were lower in patients with blood type B and O compared to blood type A, suggesting less endothelial damage.

Conclusion

Septic patients with blood type B had less endothelial damage, and a small reduction in mortality. The exposure is, however, unmodifiable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00844-2.

Chinese expert consensus on diagnosis and treatment of trauma-induced hypercoagulopathy

Trauma-induced coagulopathy (TIC) is caused by post-traumatic tissue injury and manifests as hypercoagulability that leads to thromboembolism or hypocoagulability that leads to uncontrollable massive hemorrhage. Previous studies on TIC have mainly focused on hemorrhagic coagulopathy caused by the hypocoagulable phenotype of TIC, while recent studies have found that trauma-induced hypercoagulopathy can occur in as many as 22.2-85.1% of trauma patients, in whom it can increase the risk of thrombotic events and mortality by 2- to 4-fold. Therefore, the Chinese People's Liberation Army Professional Committee of Critical Care Medicine and the Chinese Society of Thrombosis, Hemostasis and Critical Care, Chinese Medicine Education Association jointly formulated this Chinese Expert Consensus comprising 15 recommendations for the definition, pathophysiological mechanism, assessment, prevention, and treatment of trauma-induced hypercoagulopathy.

Trauma-Induced Coagulopathy: Overview of an Emerging Medical Problem from Pathophysiology to Outcomes

Coagulopathy induced by major trauma is common, affecting approximately one-third of patients after trauma. It develops independently of iatrogenic, hypothermic, and dilutive causes (such as iatrogenic cause in case of fluid administration), which instead have a pejorative aspect on coagulopathy. Notwithstanding the continuous research conducted over the past decade on Trauma-Induced Coagulopathy (TIC), it remains a life-threatening condition with a significant impact on trauma mortality. We reviewed the current evidence regarding TIC diagnosis and pathophysiological mechanisms and summarized the different iterations of optimal TIC management strategies among which product resuscitation, potential drug administrations, and hemostatis-focused approaches. We have identified areas of ongoing investigation and controversy in TIC management.

Glycocalyx components affect platelet function, whole blood coagulation, and fibrinolysis: an in vitro study suggesting a link to trauma-induced coagulopathy

BACKGROUND

The mechanisms of trauma induced coagulopathy (TIC) are considered multifactorial. Amongst others, however, shedding of the endothelial glycocalyx resulting in increased concentrations of glycocalyx fragments in plasma might also play a role. Thus, we hypothesized that shedded glycocalyx components affect coagulation and may act as humoral mediators of TIC.

METHODS

To investigate effects of heparan sulfate, chondroitin sulfate, syndecan-1, versican, and thrombomodulin we added these fragments to in vitro assays of whole blood from healthy volunteers to yield concentrations observed in trauma patients. Platelet function, whole blood coagulation, and fibrinolysis were measured by standard coagulation tests, impedance aggregometry (IA), and viscoelastic tests (VET). To assess dose-response relationships, we performed IA with increasing concentrations of versican and VET with increasing concentrations of thrombomodulin.

RESULTS

Intrinsically activated clotting times (i.e., activated partial thromboplastin time and intrinsically activated VET with and without heparinase) were unaffected by any glycocalyx fragment. Thrombomodulin, however, significantly and dose-dependently diminished fibrinolysis as assessed by VET with exogenously added rt-PA, and increased rt-PA-induced lysis Indices after 30 (up to 108% of control, p <  0,0001), 45 (up to 368% of control, p <  0,0001), and 60 min (up to 950% of control, p <  0,0001) in VET. Versican impaired platelet aggregation in response to arachidonic acid (up to - 37,6%, p <  0,0001), ADP (up to - 14,5%, p <  0,0001), and collagen (up to - 31,8%, p <  0,0001) in a dose-dependent manner, but did not affect TRAP-6 induced platelet aggregation. Clotting time in extrinsically activated VET was shortened by heparan sulfate (- 7,2%, p = 0,024), chondroitin sulfate (- 11,6%, p = 0,016), versican (- 13%, p = 0,012%), and when combined (- 7,2%, p = 0,007).

CONCLUSIONS

Glycocalyx components exert distinct inhibitory effects on platelet function, coagulation, and fibrinolysis. These data do not support a 'heparin-like auto-anticoagulation' by shed glycosaminoglycans but suggest a possible role of versican in trauma-induced thrombocytopathy and of thrombomodulin in trauma-associated impairment of endogenous fibrinolysis.

Severe mesenteric traction syndrome is associated with increased systemic inflammatory response, endothelial dysfunction, and major postoperative morbidity

This study aimed to determine if mesenteric traction syndrome (MTS) triggers increased systemic inflammation and endothelial cell dysfunction. Patients developing severe MTS had pronounced early IL6 elevations followed by endothelial cell damage. Furthermore, these processes were associated with increased postoperative morbidity.

OBJECTIVE

To determine whether mesenteric traction syndrome (MTS) leads to increased systemic inflammation and dysfunction of the glycocalyx and endothelial cell and whether this correlates with the degree of postoperative morbidity.

INTRODUCTION

Severe MTS is associated with increased postoperative morbidity following major gastrointestinal surgery, but the pathophysiological mechanism has not been previously explored. Systemic inflammatory response and impaired glycocalyx and endothelial cells may be responsible for the development of symptoms.

METHODS

The study analyzed prospectively collected data from two cohorts (n = 67). The severity of the MTS response was graded intraoperatively and blood samples for PGI₂, catecholamines, IL6, and endothelial biomarkers obtained at predefined time points.

RESULTS

Patients undergoing either esophagectomy (n = 45) or gastrectomy (n = 22) were included. Surgery led to significantly increased plasma concentrations of all biomarkers. Yet, patients who developed severe MTS had higher baseline epinephrine levels (p < 0.05) and higher levels of PGI₂ (p < 0.05), Syndecan-1 (p < 0.001), and sVEGFR1 (p < 0.001). Peak values of IL6, Syndecan-1, sVEGFR1, and sTM all correlated to peak PGI₂. Lastly, patients with high postoperative morbidity had higher baseline epinephrine (p = 0.009) and developed higher plasma IL6 (p = 0.007) and sTM (p = 0.022).

CONCLUSION

The development of severe MTS during upper gastrointestinal surgery is associated with preoperative elevated plasma epinephrine and further a more pronounced proinflammatory response and damage to the vascular endothelium. The increased postoperative morbidity seen in patients with severe MTS may thus, in part, be explained by an inherent susceptibility towards an inappropriate secretion of PGI₂, which leads to an increased surgical stress response and endothelial damage. These findings must be confirmed in a new prospective cohort.

Endothelial Dysfunction is Associated With Increased Incidence, Worsened Severity, and Prolonged Duration of Acute Kidney Injury After Severe Trauma

INTRODUCTION

Nearly half of severely injured patients suffer acute kidney injury (AKI), but little is known about its pathogenesis or optimal management. We hypothesized that endothelial dysfunction, evidenced by elevated systemic soluble thrombomodulin (sTM) and syndecan-1, would be associated with higher incidence, worsened severity, and prolonged duration of AKI after severe trauma.

METHODS

A single-center cohort study of severely injured patients surviving ≥24 h from 2012 to 2016 was performed. Arrival plasma sTM and syndecan-1 were measured by ELISA. Outcomes included 7-day AKI incidence, stage, and prolonged AKI ≥2 days. The Kidney Disease Improving Global Outcomes guidelines were used for AKI diagnosis and staging. Univariate and multivariable analyses were performed.

RESULTS

Of 477 patients, 78% were male. Patients had a median age of 38 (interquartile ranges [IQR] 27-54) and injury severity score of 17 (IQR 10-26). AKI developed in 51% of patients. Those with AKI were older and displayed worse arrival physiology. Patients with AKI had higher plasma levels of syndecan-1 (median 34.9 ng/mL vs. 20.1 ng/mL) and sTM (6.5 ng/mL vs. 4.8 ng/mL). After adjustment, sTM and syndecan-1 were both associated with higher AKI incidence, worse AKI severity, and prolonged AKI duration. The strength and precision of the association of sTM and these outcomes were greater than those for syndecan-1. A sensitivity analysis excluding patients with AKI on arrival demonstrated the same relationship.

CONCLUSIONS

Elevated sTM and syndecan-1, indicating endothelial dysfunction, were associated with higher incidence, worsened severity, and prolonged duration of AKI after severe trauma. Treatments that stabilize the endothelium hold promise for AKI treatment in severely injured patients.

Pulmonary midkine inhibition ameliorates sepsis induced lung injury

Background

Midkine is a multi-functional molecule participating in a various key pathological process. We aimed to evaluate the change of midkine in sepsis and its association with angiotensin-converting enzyme (ACE) system, as well as the mechanism by which midkine induced in sepsis and lung injury.

Methods

The peripheral blood sample of septic patients on admission was obtained and measured for midkine, ACE and angiotensin II. Cecal ligation and puncture (CLP) mouse model was used, and adeno-associated virus (AAV) was stilled trans-trachea for regional targeting midkine expression, comparing the severity of lung injury. Furthermore, we studied the in vitro mechanism of midkine activates ACE system by using inhibitors targeting candidate receptors of midkine, and its effects on the vascular endothelial cells.

Results

Plasma midkine was significantly elevated in sepsis, and was closely associated with ACE system. Both circulating and lung midkine was increased in CLP mouse, and was related to severe lung injury. Regional interfering midkine expression in lung tissue by AAV could alleviate acute lung injury in CLP model. In vitro study elucidated that Notch 2 participated in the activation of ACE system and angiotensin II release, induced by midkine and triggered vascular endothelial injury by angiotensin II induced reactive oxygen species production.

Conclusions

Midkine inhibition ameliorates sepsis induced lung injury, which might via ACE/Ang II pathway and the participation of Notch 2 in the stimulation of ACE.

Trial registration

Clinicaltrials.gov NCT02605681. Registered 12 November 2015

Hemorrhagic Shock and Resuscitation Causes Glycocalyx Shedding and Endothelial Oxidative Stress Preferentially in the Lung and Intestinal Vasculature

INTRODUCTION

Hemorrhagic shock has recently been shown to cause shedding of a carbohydrate surface layer of endothelial cells known as the glycocalyx. This shedding of the glycocalyx is thought to be a mediator of the coagulopathy seen in trauma patients. Clinical studies have demonstrated increases in shed glycocalyx in the blood after trauma, and animal studies have measured glycocalyx disruption in blood vessels in the lung, skeletal muscle, and mesentery. However, no study has measured glycocalyx disruption across a wide range of vascular beds to quantify the primary locations of this shedding.

METHODS

In the present study, we used a rat model of hemorrhagic shock and resuscitation to more comprehensively assess glycocalyx disruption across a range of organs. Glycocalyx disruption was assessed by fluorescent-labelled wheat germ agglutinin or syndecan-1 antibody staining in flash frozen tissue.

RESULTS

We found that our model did elicit glycocalyx shedding, as assessed by an increase in plasma syndecan-1 levels. In tissue sections, we found that the greatest glycocalyx disruption occurred in vessels in the lung and intestine. Shedding to a lesser extent was observed in vessels of the brain, heart, and skeletal muscle. Liver vessel glycocalyx was unaffected, and kidney vessels, including the glomerular capillaries, displayed an increase in glycocalyx. We also measured reactive oxygen species (ROS) in the endothelial cells from these organs, and found that the greatest increase in ROS occurred in the two beds with the greatest glycocalyx shedding, the lungs and intestine. We also detected fibrin deposition in lung vessels following hemorrhage-resuscitation.

CONCLUSIONS

We conclude that the endothelium in the lungs and intestine are particularly susceptible to the oxidative stress of hemorrhage-resuscitation, as well as the resulting glycocalyx disruption. Thus these two vessel beds may be important drivers of coagulopathy in trauma patients.

SARS-CoV-2 infection: molecular mechanisms of severe outcomes to suggest therapeutics

Introduction:The year 2020 was defined by the 29,903 base pairs of RNA that codes for the SARS-CoV-2 genome. SARS-CoV-2 infects humans to cause COVID-19, spreading from patient-to-patient yet impacts patients very divergently.Areas covered: Within this review, we address the known molecular mechanisms and supporting data for COVID-19 clinical course and pathology, clinical risk factors and molecular signatures, therapeutics of severe COVID-19, and reinfection/vaccination. Literature and published datasets were reviewed using PubMed, Google Scholar, and NCBI SRA tools. The combination of exaggerated cytokine signaling, pneumonia, NETosis, pyroptosis, thrombocytopathy, endotheliopathy, multiple organ dysfunction syndrome (MODS), and acute respiratory distress syndrome (ARDS) create a positive feedback loop of severe damage in patients with COVID-19 that impacts the entire body and may persist for months following infection. Understanding the molecular pathways of severe COVID-19 opens the door for novel therapeutic design. We summarize the current insights into pathology, risk factors, secondary infections, genetics, omics, and drugs being tested to treat severe COVID-19.Expert opinion: A growing level of support suggests the need for stronger integration of biomarkers and precision medicine to guide treatment strategies of severe COVID-19, where each patient has unique outcomes and thus require guided treatment.

Terms, Definitions, Nomenclature, and Routes of Fluid Administration

Fluid therapy is administered to veterinary patients in order to improve hemodynamics, replace deficits, and maintain hydration. The gradual expansion of medical knowledge and research in this field has led to a proliferation of terms related to fluid products, fluid delivery and body fluid distribution. Consistency in the use of terminology enables precise and effective communication in clinical and research settings. This article provides an alphabetical glossary of important terms and common definitions in the human and veterinary literature. It also summarizes the common routes of fluid administration in small and large animal species.

Hemostatic defects in massive transfusion: an update and treatment recommendations

INTRODUCTION

Acute hemorrhage is a global healthcare issue, and remains the leading preventable cause of death in trauma. Acute severe hemorrhage can be related to traumatic, peripartum, gastrointestinal, and procedural causes. Hemostatic defects occur early in patients requiring massive transfusion. Early recognition and treatment of hemorrhage and hemostatic defects are required to save lives and to achieve optimal patient outcomes.

AREAS COVERED

This review discusses current evidence and trials aimed at identifying the optimal treatment for hemostatic defects in hemorrhage and massive transfusion. Literature search included PubMed and Embase.

EXPERT OPINION

Patients with acute hemorrhage requiring massive transfusion commonly develop coagulopathy due to specific hemostatic defects, and accurate diagnosis and prompt correction are required for definitive hemorrhage control. Damage control resuscitation and massive transfusion protocols are optimal initial treatment strategies, followed by goal-directed individualized resuscitation using real-time coagulation monitoring. Distinct phenotypes exist in trauma-induced coagulopathy, including 'Bleeding' or 'Thrombotic' phenotypes, and hyperfibrinolysis vs. fibrinolysis shutdown. The trauma 'lethal triad' (hypothermia, coagulopathy, acidosis) has been updated to the 'lethal diamond' (including hypocalcemia). A number of controversies in optimal management exist, including whole blood vs. component therapy, use of factor concentrates vs. blood products, optimal use of tranexamic acid, and prehospital plasma and tranexamic acid administration.

Obesity and impaired barrier function after shock: A biomimetic in vitro model using microfluidics

BACKGROUND

Impaired microvascular perfusion in the obese patient has been linked to chronic adverse health consequences. The impact on acute illnesses including trauma, sepsis, and hemorrhagic shock (HS) is uncertain. Studies have shown that endothelial glycocalyx and vascular endothelial derangements are causally linked to perfusion abnormalities. Trauma and HS are also associated with impaired microvascular perfusion in which glycocalyx injury and endothelial dysfunction are sentinel events. We postulate that obesity may impact the adverse consequences of HS on the vascular barrier. This was studied in vivo in a biomimetic model of HS using microfluidic technology.

METHODS

Human umbilical vein endothelial cell monolayers were established in a microfluidic device. Cells were exposed to standard or biomimetic shock conditions (hypoxia plus epinephrine) followed by perfusion from plasma obtained from obese or nonobese subjects. Endothelial glycocalyx and endothelial cellular injury were then determined.

RESULTS

Plasma from nonobese patients completely reversed glycocalyx and endothelial vascular barrier injury. Plasma from obese patients was only partially protective and was associated with differences in adipokines and other substances in the plasma of these patients.

CONCLUSION

Our study supports that obesity impairs HS resuscitation. This may be due to microrheological differences between nonobese and obese individuals and may contribute to the poorer outcome in this patient population.

Targeting Endothelial Dysfunction in Acute Critical Illness to Reduce Organ Failure

During hyperinflammatory conditions that can occur in acute critical illness, such as shock or hypoperfusion, inflammatory mediators activate the endothelium, fueling a proinflammatory host-response as well as procoagulant processes. These changes result in shedding of the glycocalyx, endothelial hyperpermeability, edema formation, and lead to disturbed microcirculatory perfusion and organ failure. Different fluid strategies that are used in shock may have differential effects on endothelial integrity. Collectively, low protein content fluids seem to have negative effects on the endothelial glycocalyx, aggravating endothelial hyperpermeability, whereas fluids containing albumin or plasma proteins may be superior to normal saline in protecting the glycocalyx and endothelial barrier function. Targeting the endothelium may be a therapeutic strategy to limit organ failure, which hitherto has not received much attention. Treatment targets aimed at restoring the endothelium should focus on maintaining glycocalyx function and/or targeting coagulation pathways or specific endothelial receptors. Potential treatments could be supplementing glycocalyx constituents or inhibiting glycocalyx breakdown. In this review, we summarize mechanisms of endothelial dysfunction during acute critical illness, such as the systemic inflammatory response, shedding of the glycocalyx, endothelial activation, and activation of coagulation. In addition, this review focuses on the effects of different fluid strategies on endothelial permeability. Also, potential mechanisms for treatment options to reduce endothelial hyperpermeability with ensuing organ failure are evaluated. Future research is needed to elucidate these pathways and to translate these data to the first human safety and feasibility trials.

Vascular Endothelial Glycocalyx Damage in COVID-19

The new coronavirus disease-2019 (COVID-19), which is spreading around the world and threatening people, is easily infecting a large number of people through airborne droplets; moreover, patients with hypertension, diabetes, obesity, and cardiovascular disease are more likely to experience severe conditions. Vascular endothelial dysfunction has been suggested as a common feature of high-risk patients prone to severe COVID-19, and measurement of vascular endothelial function may be recommended for predicting severe conditions in high-risk patients with COVID-19. However, fragmented vascular endothelial glycocalyx (VEGLX) is elevated in COVID-19 patients, suggesting that it may be useful as a prognostic indicator. Although the relationship between VEGLX and severe acute respiratory syndrome coronavirus 2 infections has not been well studied, some investigations into COVID-19 have clarified the relationship between VEGLX and the mechanism that leads to severe conditions. Clarifying the usefulness of VEGLX assessment as a predictive indicator of the development of severe complications is important as a strategy for confronting pandemics caused by new viruses with a high affinity for the vascular endothelium that may recur in the future.

An Assessment of Research Priorities to Dampen the Pendulum Swing of Burn Resuscitation

On June 17 to 18, 2019, the American Burn Association, in conjunction with Underwriters Laboratories, convened a group of experts on burn resuscitation in Washington, DC. The goal of the meeting was to identify and discuss novel research and strategies to optimize the process of burn resuscitation. Patients who sustain a large thermal injury (involving >20% of the total body surface area [TBSA]) face a sequence of challenges, beginning with burn shock. Over the last century, research has helped elucidate much of the underlying pathophysiology of burn shock, which places multiple organ systems at risk of damage or dysfunction. These studies advanced the understanding of the need for fluids for resuscitation. The resultant practice of judicious and timely infusion of crystalloids has improved mortality after major thermal injury. However, much remains unclear about how to further improve and customize resuscitation practice to limit the morbidities associated with edema and volume overload. Herein, we review the history and pathophysiology of shock following thermal injury, and propose some of the priorities for resuscitation research. Recommendations include: studying the utility of alternative endpoints to resuscitation, reexamining plasma as a primary or adjunctive resuscitation fluid, and applying information about inflammation and endotheliopathy to target the underlying causes of burn shock. Undoubtedly, these future research efforts will require a concerted effort from the burn and research communities.

Endothelial Responses in Sepsis

Endothelial cells (ECs) are vascular, nonconventional immune cells that play a major role in the systemic response after bacterial infection to limit its dissemination. Triggered by exposure to pathogens, microbial toxins, or endogenous danger signals, EC responses are polymorphous, heterogeneous, and multifaceted. During sepsis, ECs shift toward a proapoptotic, proinflammatory, proadhesive, and procoagulant phenotype. In addition, glycocalyx damage and vascular tone dysfunction impair microcirculatory blood flow, leading to organ injury and, potentially, life-threatening organ failure. This review aims to cover the current understanding of the EC adaptive or maladaptive response to acute inflammation or bacterial infection based on compelling recent basic research and therapeutic clinical trials targeting microvascular and endothelial alterations during septic shock.

Enigmatic role of coagulopathy among sepsis survivors: a review of coagulation abnormalities and their possible link to chronic critical illness

There are sparse clinical data addressing the persistence of disordered coagulation in sepsis and its role in chronic critical illness. Coagulopathy in the absence of anticoagulant therapy and/or liver disease can be highly variable in sepsis, but it tends to be prolonged in patients in the intensive care unit with a length of stay greater than 14 days. These coagulation abnormalities tend to precede multisystem organ failure and persistence of these coagulation derangements can predict 28-day mortality. The studies evaluated in this review consistently link sepsis-associated coagulopathy to poor long-term outcomes and indicate that disordered coagulation is associated with unfavorable outcomes in chronic critical illness. However, the causative mechanism and the definitive link remain unclear. Longer follow-up and more granular data will be required to fully understand coagulopathy in the context of chronic critical illness.

Disseminated intravascular coagulation: new identity as endotheliopathy-associated vascular microthrombotic disease based on in vivo hemostasis and endothelial molecular pathogenesis

Disseminated intravascular coagulation (DIC) can be correctly redefined as disseminated intravascular microthrombosis based on "two-path unifying theory" of in vivo hemostasis. "DIC" is a form of vascular microthrombotic disease characterized by "microthrombi" composed of platelets and unusually large von Willebrand factor multimers (ULVWF). Microthrombotic disease includes not only "DIC", but also microthrombosis occurring in thrombotic thrombocytopenic purpura (TTP), TTP-like syndrome, and focal, multifocal and localized microthrombosis. Being a hemostatic disease, microthrombotic disease occurs as a result of lone activation of ULVWF path via partial in vivo hemostasis. In endothelial injury associated with critical illnesses such as sepsis, the vascular damage is limited to the endothelial cell and activates ULVWF path. In contrast, in intravascular traumatic injury, the local damage may extend from the endothelial cell to subendothelial tissue and sometimes beyond, and activates both ULVWF and tissue factor (TF) paths. When endotheliopathy triggers exocytosis of ULVWF and recruits platelets, ULVWF path is activated and promotes microthrombogenesis to produce microthrombi composed of microthrombi strings, but when localized vascular damage causes endothelial and subendothelial tissue damage, both ULVWF and TF paths are activated and promote macrothrombogenesis to produce macrothrombus made of complete "blood clots". Currently, "DIC" concept is ascribed to activated TF path leading to fibrin clots. Instead, it should be correctly redefined as microthrombosis caused by activation of ULVWF path, leading to endotheliopathy-associated microthrombosis. The correct term for acute "DIC" is disseminated microthrombosis-associated hepatic coagulopathy, and that for chronic "DIC" is disseminated microthrombosis without hepatic coagulopathy. TTP-like syndrome is hematologic phenotype of endotheliopathy-associated microthrombosis. This correct concept of "DIC" is identified from novel theory of "in vivo hemostasis", which now can solve every mystery associated with "DIC" and other associated thrombotic disorders. Thus, sepsis-associated coagulopathy is not "DIC", but is endotheliopathy-associated vascular microthrombotic disease.

[Hyperfibrinolysis after Resuscitation due to Acute Pulmonary Artery Embolism]

In an 81-year-old patient, acute hemodynamic instability requiring resuscitation occurred during an elective transurethral prostate resection. The procedure was ended prematurely and after ROSC a CT diagnosis was carried out, which confirmed the suspected diagnosis of fulminant pulmonary embolism. Anticoagulant therapy with heparin was initiated. About two hours after admission to the intensive care unit, hemorrhage requiring massive transfusion developed, which according to viscoelastometric diagnostics was most likely due to fulminant hyperfibrinolysis. This case report describes the pathophysiology of so-called post-cardiac arrest coagulopathy and discusses the use of antifibrinolytic therapy in patients with thrombotic complications such as pulmonary artery embolism.

The therapeutic efficacy of adjunct therapeutic plasma exchange for septic shock with multiple organ failure: a single-center experience

Background

Sepsis remains a common condition with high mortality when multiple organ failure develops. The evidence for therapeutic plasma exchange (TPE) in this setting is promising but inconclusive. Our study aims to evaluate the efficacy of adjunct TPE for septic shock with multiple organ failure compared to standard therapy alone.

Methods

A retrospective, observational chart review was performed, evaluating outcomes of patients with catecholamine-resistant septic shock and multiple organ failure in intensive care units at a tertiary care hospital in Winston-Salem, NC, from August 2015 to March 2019. Adult patients with catecholamine-resistant septic shock (≥ 2 vasopressors) and evidence of multiple organ failure were included. Patients who received adjunct TPE were identified and compared to patients who received standard care alone. A propensity score using age, gender, chronic co-morbidities (HTN, DM, CKD, COPD), APACHE II score, SOFA score, lactate level, and number of vasopressors was used to match patients, resulting in 40 patients in each arm.

Results

The mean baseline APACHE II and SOFA scores were 32.5 and 14.3 in TPE patients versus 32.7 and 13.8 in control patients, respectively. The 28-day mortality rate was 40% in the TPE group versus 65% in the standard care group (p = 0.043). Improvements in baseline SOFA scores at 48 h were greater in the TPE group compared to standard care alone (p = 0.001), and patients receiving adjunct TPE had a more favorable fluid balance at 48 h (p = 0.01). Patients receiving adjunct TPE had longer ICU and hospital lengths of stay (p = 0.003 and p = 0.006, respectively).

Conclusions

Our retrospective, observational study in adult patients with septic shock and multiple organ failure demonstrated improved 28-day survival with adjunct TPE compared to standard care alone. Hemodynamics, organ dysfunction, and fluid balance all improved with adjunct TPE, while lengths of stay were increased in survivors. The study design does not allow for a generalized statement of support for TPE in all cases of sepsis with multiple organ failure but offers valuable information for a prospective, randomized clinical trial.

Endothelial glycocalyx damage as a systemic inflammatory microvascular endotheliopathy in COVID-19

In atherosclerosis patients, vascular endothelial dysfunction is commonly observed alongside damage of the vascular endothelial glycocalyx, an extracellular matrix bound to and encapsulating the endothelial cells lining the blood vessel wall. Although atherosclerotic risk factors have been reported in severe patients with coronavirus disease 2019 (COVID-19), the exact mechanisms are unclear. The mortality associated with the COVID-19 outbreak is increased by comorbidities, including hypertension, diabetes, obesity, chronic obstructive pulmonary disease (COPD), and cardiovascular disease. Besides, older individuals and smokers have significantly worse outcomes. Interestingly, these comorbidities and risk factors are consistent with the pathophysiology that causes vascular endothelial glycocalyx damage. Moreover, vascular glycocalyx dysfunction causes microvascular leakage, which results in interstitial pulmonary abnormal shadows (multiple patchy shadows with a ground glass inter-pneumonic appearance). This is frequently followed by severe acute respiratory distress syndrome (ARDS), closely related to coagulo-fibrinolytic changes contributing to disseminated intravascular coagulation (DIC) and Kawasaki disease shock syndrome, as well as inducing activation of the coagulation cascade, leading to thromboembolism and multiple organ failure. Notably, SARS-CoV-2, the causative virus of COVID-19, binds to ACE2, which is abundantly present not only in human epithelia of the lung and the small intestine, but also in vascular endothelial cells and arterial smooth muscle cells. Moreover, COVID-19 can induce severe septic shock, and sepsis can easily lead to systemic degradation of the vascular endothelial glycocalyx. In the current review, we propose new concepts and therapeutic goals for COVID-19-related vascular endothelial glycocalyx damage, based on previous vascular endothelial medicine research.

Effect of Coagulation Factor Concentrates on Markers of Endothelial Cell Damage in Experimental Hemorrhagic Shock

BACKGROUND

Plasma-based resuscitation showed protective effects on the endothelial glycocalyx compared with crystalloid resuscitation. There is paucity of data regarding the effect of coagulation factor concentrates (CFC) on the glycocalyx in hemorrhagic shock (HS). We hypothesized that colloid-based resuscitation supplemented with CFCs offers a therapeutic value to treat endothelial damage following HS.

METHODS

Eighty-four rats were subjected to pressure-controlled (mean arterial pressure (MAP) 30-35 mm Hg) and lab-guided (targeted cutoff: lactate >2.2. mmol/L and base deficit > 5.5 mmol/L) HS. Animals were resuscitated with fresh frozen plasma (FFP), human albumin (HA) or Ringer's lactate (RL) and RL or HA supplemented with fibrinogen concentrate (FC) or prothrombin complex concentrate (PCC). Serum epinephrine and the following markers of endothelial damage were assessed at baseline and at the end-of-observation (120 min after shock was terminated): syndecan-1, heparan sulfate, and soluble vascular endothelial growth factor receptor 1 (sVEGFR 1).

RESULTS

Resuscitation with FFP had no effect on sVEGFR1 compared with crystalloid-based resuscitation (FFP: 19.3 ng/mL vs. RL: 15.9 ng/mL; RL+FC: 19.7 ng/mL; RL+PCC: 18.9 ng/mL; n.s.). At the end-of-observation, syndecan-1 was similar among all groups. Interestingly, HA+FC treated animals displayed the highest syndecan-1 concentration (12.07 ng/mL). Resuscitation with FFP restored heparan sulfate back to baseline (baseline: 36 ng/mL vs. end-of-observation: 36 ng/mL).

CONCLUSION

The current study revealed that plasma-based resuscitation normalized circulating heparan sulfate but not syndecan-1. Co-administration of CFC had no further effect on glycocalyx shedding suggesting a lack of its therapeutic potential.

LEVEL OF EVIDENCE

VExperimental in vivo study.

Multiple limb compartment syndrome as a manifestation of capillary leak syndrome secondary to metformin and dipeptidyl peptidase IV inhibitor overdose: A case report

RATIONALE

Capillary leak syndrome is a condition that increases systemic capillary permeability and causes characteristic manifestations such as recurrent hypovolemia, systemic edema, and hemoconcentration. Acute limb compartment syndrome is a possible complication of severe capillary leak syndrome. However, timely diagnosis and prompt treatment are challenging because of atypical presentation.

PATIENT CONCERNS

An 18-year-old woman with a history of clinical depression was admitted to our intensive care unit (ICU) because of metformin and vildagliptin overdose. She developed marked vasodilatory shock with recurrent severe hypovolemia and disseminated intravascular coagulation. After urgent hemodialysis and plasma exchange, she started to stabilize hemodynamically. However, her limbs became stone-hard with massive edema. Her serum creatinine kinase level increased to an extremely high level.

DIAGNOSIS

Extremities were distended, and her skin developed pallor with blistering. Intramuscular pressure in both forearms and lower legs was significantly elevated.

INTERVENTIONS

Decompressive fasciotomy was performed. Hemodialysis was continued because of rhabdomyolyses-induced acute kidney injury.

OUTCOMES

The patient was finally able to walk by herself at the time of hospital discharge on day 109.

LESSONS

The possibility of acute compartment syndrome should be considered in patients with marked capillary leakage, especially after aggressive fluid resuscitation. It is important to be aware of the compartment syndrome in an ICU setting because communication barriers often mask typical symptoms and make diagnosis difficult.

Treatment Modalities in the Intensive Care Unit for Coronavirus Disease 2019

The last Influenza pandemic of 1918 happened before the advent of modern medicine. We have come a long way since then. But the COVID-19 pandemic has still caught us unprepared on many fronts. The review focuses on the management of critically ill COVID-19 patients and the various treatment modalities being employed to counter this incompletely understood disease.

The Diagnosis and Treatment of Acute Traumatic Bleeding and Coagulopathy

BACKGROUND

Uncontrolled bleeding with trauma-induced coagulopathy (TIC) is still the most common avoidable cause of death in multiple trauma. The aging of the population has led to an increasing number of bleeding trauma patients with pre-existing anticoagulation. Such patients are not treated uniformly, even in major trauma centers.

METHODS

This review is based on a selective search of the literature (Medline/PubMed, Cochrane Reviews) and summarizes current treatment recommendations, including those of the newly revised European trauma guidelines.

RESULTS

The treatment of traumatic hemorrhage begins at the site of the accident, with compression, tourniquets, pelvic binders, and rapid transport to a certified trauma center. The early use of tourniquets was shown to lessen the trans- fusion requirement (packed red blood cells: 2.0 ± 0.1 vs. 9.3 ± 0.6; p < 0.001; fresh frozen plasma concentrates: 1.4 ± 0.08 vs. 6.2 ± 0.4; p < 0.001), while external pelvic stabilization was shown to reduce mortality (19.1% vs. 33.3%). Upon the patient's arrival in the hospital, steps are taken to measure, monitor, and support clotting function. Bleeding is controlled surgically according to the principles of damage control. Modern clotting management consists of goal-oriented, individualized therapy, including the use of point-of-care viscoelastic test procedures. Idarucizumab can be used as an antidote to the thrombin inhibitor dabigatran, andexanet alpha as an antidote to factor Xa inhibitors.

CONCLUSION

The evidence-based treatment of patients with hemorrhage from severe trauma, in accordance with the existing guidelines, can improve the clinical outcome. Corresponding algorithms, adapted to local logistics and infrastructure, must be developed and implemented.

Role of albumin in the preservation of endothelial glycocalyx integrity and the microcirculation: a review

The endothelial glycocalyx comprises a complex layer of membrane-bound proteoglycans, secreted glycosaminoglycans, glycoproteins, glycolipids and bound plasma proteins such as albumin and antithrombin associated with the endothelial surface. The glycocalyx plays an important role in vascular homeostasis, regulating vascular permeability and cell adhesion, and acts as a mechanosensor for hemodynamic shear stresses; it also has antithrombotic and anti-inflammatory functions. Plasma proteins such as albumin are physiologically bound within the glycocalyx, thus contributing to stability of the layer. Albumin is the major determinant of plasma colloid osmotic pressure. In addition, albumin transports sphingosine-1-phosphate which has protective endothelial effects, acts as a free radical scavenger, and has immunomodulatory and anti-inflammatory effects. This review examines the physiological function of the endothelial glycocalyx and the role of human albumin in preserving glycocalyx integrity and the microcirculation.

The successful use of therapeutic plasma exchange for severe COVID-19 acute respiratory distress syndrome with multiple organ failure

The COVID-19 pandemic has brought about an urgent need for effective treatment, while conserving vital resources such as intensive care unit beds and ventilators. Antivirals, convalescent plasma, and biologics have been used with mixed results. The profound "cytokine storm" induced endotheliopathy and microthrombotic disease in patients with COVID-19 may lead to acute respiratory distress syndrome, sepsis, and multi-organ failure. We present a case of SARS-COV2 pneumonia with septic shock and multi-organ failure that demonstrated significant clinical improvement after therapeutic plasma exchange. A 65-year-old female with multiple comorbidities presented with progressive dyspnea and dry cough. She was found to be COVID-19 positive with pneumonia, and developed progressive hypoxemia and shock requiring vasopressors, cardioversion, and non-invasive positive pressure ventilation. Given her worsening sepsis with multi-organ failure, she underwent therapeutic plasma exchange with rapid clinical improvement. Her case supports the theory that plasma exchange may help abate the "cytokine storm" induced endotheliopathy and microthrombosis associated with COVID-19. Further studies are needed to identify markers of this pathway and the potential role of plasma exchange in these critically ill patients.

Medical Management of COVID-19: Evidence and Experience

Coronavirus disease 2019 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and this infectious disease is termed COVID-19 in short. On a global scale, as of June 1, 2020, the World Health Organization (WHO) published statistics of 6,057,853 infected patients and 371,166 deaths worldwide. Despite reported observational data about the experimental use of certain drugs, there is no conclusively proven curative therapy for COVID-19 as of now; however, remdesivir received emergency use authorization (EUA) by the Food and Drug Administration (FDA) recently for use in patients hospitalized with COVID-19. There are several ongoing clinical trials related to the pharmacological choices of therapy for COVID-19 patients; however, drug trials related to observational studies so far have yielded mixed results and therefore have created a sense of confusion among healthcare professionals (HCPs). In this review article, we seek to collate and provide a summary of treatment strategies for COVID-19 patients with a variable degree of illness and discuss pharmacologic and other therapies intended to be used either as experimental medicine/therapy or as part of supportive care in complicated cases of COVID-19.

Evaluation and Predictors of Fluid Resuscitation in Patients With Severe Sepsis and Septic Shock

OBJECTIVES

Rapid fluid resuscitation has become standard in sepsis care, despite "low-quality" evidence and absence of guidelines for populations "at risk" for volume overload. Our objectives include as follows: 1) identify predictors of reaching a 30 mL/kg crystalloid bolus within 3 hours of sepsis onset (30by3); 2) assess the impact of 30by3 and fluid dosing on clinical outcomes; 3) examine differences in perceived "at-risk" volume-sensitive populations, including end-stage renal disease, heart failure, obesity, advanced age, or with documentation of volume "overload" by bedside examination.

DESIGN

Retrospective cohort study. All outcome analyses controlled for sex, end-stage renal disease, heart failure, sepsis severity (severe sepsis vs septic shock), obesity, Mortality in Emergency Department Sepsis score, and time to antibiotics.

SETTING

Urban, tertiary care center between January 1, 2014, and May 31, 2017.

PATIENTS

Emergency Department treated adults (age ≥18 yr; n = 1,032) with severe sepsis or septic shock.

INTERVENTIONS

Administration of IV fluids by bolus.

MEASUREMENTS AND MAIN RESULTS

In total, 509 patients received 30by3 (49.3%). Overall mortality was 17.1% (n = 176), with 20.4% mortality in the shock group. Patients who were elderly (odds ratio, 0.62; 95% CI, 0.46-0.83), male (odds ratio, 0.66; CI, 0.49-0.87), obese (odds ratio, 0.18; CI, 0.13-0.25), or with end-stage renal disease (odds ratio, 0.23; CI, 0.13-0.40), heart failure (odds ratio, 0.42; CI, 0.29-0.60), or documented volume "overload" (odds ratio, 0.30; CI, 0.20-0.45) were less likely to achieve 30by3. Failure to meet 30by3 had increased odds of mortality (odds ratio, 1.52; CI, 1.03-2.24), delayed hypotension (odds ratio, 1.42; CI, 1.02-1.99), and increased ICU stay (~2 d) (β = 2.0; CI, 0.5-3.6), without differential effects for "at-risk" groups. Higher fluid volumes administered by 3 hours correlated with decreased mortality, with a plateau effect between 35 and 45 mL/kg (p < 0.05).

CONCLUSIONS

Failure to reach 30by3 was associated with increased odds of in-hospital mortality, irrespective of comorbidities. Predictors of inadequate resuscitation can be identified, potentially leading to interventions to improve survival. These findings are retrospective and require future validation.

Hypoxia/reoxygenation decreases endothelial glycocalyx via reactive oxygen species and calcium signaling in a cellular model for shock

BACKGROUND

Ischemia/reperfusion injury (IRI) has been shown to cause endothelial glycocalyx (EG) damage.Whether the hypoxic/ischemic insult or the oxidative and inflammatory stress of reperfusion plays a greater part in glycocalyx damage is not known. Furthermore, the mechanisms by which IRI causes EG damage have not been fully elucidated. The aims of this study were to determine if hypoxia alone or hypoxia/reoxygenation (H/R) caused greater damage to the glycocalyx, and if this damage was mediated by reactive oxygen species (ROS) and Ca signaling.

METHODS

Human umbilical vein endothelial cells were cultured to confluence and exposed to either normoxia (30 minutes), hypoxia (2% O2 for 30 minutes), or H/R (30 minutes hypoxia followed by 30 minutes normoxia). Some cells were pretreated with ROS scavengers TEMPOL, MitoTEMPOL, Febuxostat, or Apocynin, or with the Ca chelator BAPTA or Ca channel blockers 2-aminoethoxydiphenyl borate, A967079, Pyr3, or ML204. Intracellular ROS was quantified for all groups. Endothelial glycocalyx was measured using fluorescently tagged wheat germ agglutinin and imaged with fluorescence microscopy.

RESULTS

Glycocalyx thickness was decreased in both hypoxia and H/R groups, with the decrease being greater in the H/R group. TEMPOL, MitoTEMPOL, BAPTA, and 2-aminoethoxydiphenyl borate prevented loss of glycocalyx in H/R. The ROS levels were likewise elevated compared with normoxia in both groups, but were increased in the H/R group compared with hypoxia alone. BAPTA did not prevent ROS production in either group.

CONCLUSION

In our cellular model for shock, we demonstrate that although hypoxia alone is sufficient to produce glycocalyx loss, H/R causes a greater decrease in glycocalyx thickness. Under both conditions damage is dependent on ROS and Ca signaling. Notably, we found that ROS are generated upstream of Ca, but that ROS-mediated damage to the glycocalyx is dependent on Ca.

Pathophysiological Response to Trauma-Induced Coagulopathy: A Comprehensive Review

Hypercoagulability can occur after severe tissue injury, that is likely related to tissue factor exposure and impaired endothelial release of tissue plasminogen activator (tPA). In contrast, when shock and hypoperfusion occur, activation of the protein C pathway and endothelial tPA release induce a shift from a procoagulant to a hypocoagulable and hyperfibrinolytic state with a high risk of bleeding. Both thrombotic and bleeding phenotypes are associated with increased mortality and are influenced by the extent and severity of tissue injury and degree of hemorrhagic shock. Response to trauma is a complex, dynamic process in which risk can shift from bleeding to thrombosis depending on the injury pattern, hemostatic treatment, individual responses, genetic predisposition, and comorbidities. Based on this body of knowledge, we will review and consider future directions for the management of severely injured trauma patients.

Efficacy and safety of iloprost in patients with septic shock-induced endotheliopathy-Protocol for the multicenter randomized, placebo-controlled, blinded, investigator-initiated trial

BACKGROUND

In Europe 700.000 new cases of sepsis occur annually and more than 100.000 of these patients die due to multiorgan failure (MOF). We have identified shock-induced endotheliopathy (SHINE) to be associated with development of MOF and mortality. Furthermore, in patients with septic shock those with circulating levels of thrombomodulin (TM) above 10 ng/mL have twice the mortality (56% vs 28%) than those with levels below this level. Pilot studies indicate that infusion of iloprost (1 ng/kg/min) is associated with improved endothelial function in patients with septic shock.

MATERIAL AND METHODS

This is a multicenter, randomized, blinded, investigator-initiated, adaptive phase 2B trial in up to 384 patients with septic shock-induced endotheliopathy defined by TM > 10 ng/mL who are allocated 1:1 to 72 hours continuous infusion of iloprost 1 ng/kg/min or placebo (equal volume of saline). The primary outcome is the mean daily modified Sequential Organ Failure Assessment (SOFA) score in the ICU up to day 90. Secondary outcomes include 28- and 90-day all-cause mortality, days alive without vasopressor in the ICU within 90 days, days alive without mechanical ventilation in the ICU within 90 days, days alive without renal replacement therapy in the ICU within 90 days, numbers of serious adverse reactions, and the number of serious adverse events within the first 7 days.

DISCUSSION

This trial tests the safety and efficacy of iloprost vs placebo for 72 hours in patients with septic shock and SHINE. The outcome measures focus on the potential effect of the intervention to mitigate organ failure.

TRIAL REGISTRATION

COMBAT-SHINE trial-EudraCT no. 2019-001131-31-Clinicaltrials.gov: NCT04123444-Ethics Committee no. H-19018258.

Prehospital plasma is associated with distinct biomarker expression following injury

BACKGROUNDPrehospital plasma improves survival in severely injured patients transported by air ambulance. We hypothesized that prehospital plasma would be associated with a reduction in immune imbalance and endothelial damage.METHODSWe sampled blood from 405 trauma patients enrolled in the Prehospital Air Medical Plasma (PAMPer) trial upon hospital admission (0 hours) and 24 hours post admission across 6 U.S. sites. We assayed samples for 21 inflammatory mediators and 7 markers associated with endothelial function and damage. We performed hierarchical clustering analysis (HCA) of these biomarkers of the immune response and endothelial injury. Regression analysis was used to control for differences across study and to assess any association with prehospital plasma resuscitation.RESULTSHCA distinguished two patient clusters with different injury patterns and outcomes. Patients in cluster A had greater injury severity and incidence of blunt trauma, traumatic brain injury, and mortality. Cluster A patients that received prehospital plasma showed improved 30-day survival. Prehospital plasma did not improve survival in cluster B patients. In an adjusted analysis of the most seriously injured patients, prehospital plasma was associated with an increase in adiponectin, IL-1β, IL-17A, IL-23, and IL-17E upon admission, and a reduction in syndecan-1, TM, VEGF, IL-6, IP-10, MCP-1, and TNF-α, and an increase in IL-33, IL-21, IL-23, and IL-17E 24 hours later.CONCLUSIONPrehospital plasma may ameliorate immune dysfunction and the endotheliopathy of trauma. These effects of plasma may contribute to improved survival in injured patients.TRIAL REGISTRATIONNCT01818427.FUNDINGDepartment of Defense; National Institutes of Health, U.S. Army.

The Revised Starling Equation: The Debate of Albumin Versus Crystalloids Continues

Objectives: The purpose of this critical narrative review is to discuss the revised Starling equation for microvascular fluid exchange and the associated implications for intravenous fluid administration. Data Sources: PubMed (1946 to December 2019) and EMBASE (1947 to December 2019) were used, and bibliographies of retrieved articles were searched for additional articles. Study Selection and Data Extraction: Articles pertaining to the revised Starling equation and microvascular fluid exchange. Additionally, prospective human studies involving the disposition and oncotic action of radiolabeled albumin and large randomized trials comparing fluid requirements associated with isotonic crystalloid and albumin administration were included. Data Synthesis: In the revised Starling equation, oncotic forces act across the endothelial cell layer, more specifically between the fluid in the vessel lumen and the protein-sparse subglycocalyx space. The revised Starling equation and radiolabeled investigations of albumin necessitate a reconsideration of conventional views of the plasma-expanding properties of exogenous albumin. Large clinical trials demonstrate that the administration of iso-oncotic or hyper-oncotic albumin solutions in patients undergoing resuscitation does not have the reductions in fluid requirements anticipated from a traditional understanding of the oncotic actions of albumin. Relevance to Patient Care and Clinical Practice: When used as a resuscitation fluid, albumin does not have the degree of plasma expansion or intravascular retention commonly used to justify its use. Conclusions: The principles underlying the revised Starling equation in conjunction with data from radiolabeled studies of albumin and large clinical trials demonstrate that albumin does not have the perceived degree of plasma expansion or duration of intravascular retention beyond crystalloid solutions predicted by the classic Starling equation.

Endothelial glycocalyx in acute care surgery - what anaesthesiologists need to know for clinical practice

The endothelial glycocalyx (EG) is the thin sugar-based lining on the apical surface of endothelial cells. It has been linked to the physiological functioning of the microcirculation and has been found to be damaged in critical illness and after acute care surgery. This review aims to describe the role of EG in severely injured patients undergoing surgery, discuss specific situations (e.G. major trauma, hemorrhagic shock, trauma induced coagulopathy) as well as specific interventions commonly applied in these patients (e.g. fluid therapy, transfusion) and specific drugs related to perioperative medicine with regard to their impact on EG.EG in acute care surgery is exposed to damage due to tissue trauma, inflammation, oxidative stress and inadequate fluid therapy. Even though some interventions (transfusion of plasma, human serum albumin, hydrocortisone, sevoflurane) are described as potentially EG protective there is still no specific treatment for EG protection and recovery in clinical medicine.The most important principle to be adopted in routine clinical practice at present is to acknowledge the fragile structure of the EG and avoid further damage which is potentially related to worsened clinical outcome.

The protective effect of hydroxyethyl starch solution on the glycocalyx layer in an acute hemorrhage mouse model

PURPOSE

Fluid therapy focused on glycocalyx (GCX) protection in hemorrhagic shock is a current focus of research. Hydroxyethyl starch (HES) solution is commonly used for fluid resuscitation; however, its effects on the GCX remain unclear. The primary aim of this study was to explore the protective effect of HES130 in maintaining GCX thickness and reducing plasma syndecan-1 expression.

METHODS

An acute hemorrhage murine model with the dorsal skin chambers was used to measure GCX thickness and to evaluate vascular permeability. Groups of mice were treated with normal saline (NS), albumin (NS-A), HES130 (NS-V), or no exsanguination or infusion (C). We measured syndecan-1 plasma concentrations, performed blood gas analysis, and analyzed the 7-day cumulative mortality.

RESULTS

GCX thickness in NS mice was significantly reduced compared to that in group C, but no other groups showed a difference compared to group C. The plasma concentration of syndecan-1 was significantly higher in NS mice than in group C. There were no significant differences in the fluorescence intensity of dextran in the interstitial space. HES70 leakage was suppressed in NS-V mice compared to those in other groups. HES70 was localized to the inner vessel wall in C, NS, and NS-A mice, but not in group NS-V. Blood gas analysis indicated that pH and lactate showed the greatest improvements in NS-V mice. The 7-day cumulative mortality rate was the highest in group NS.

CONCLUSION

Resuscitation with HES130 protected the GCX and suppressed vascular permeability of HES70 during early stages of acute massive hemorrhage.

Reversible Microvascular Hyporeactivity to Acetylcholine During Diabetic Ketoacidosis

OBJECTIVES

Metabolic acidosis is commonly observed in critically ill patients. Experimental studies suggested that acidosis by itself could impair vascular function, but this has been poorly investigated in human.

DESIGN

Prospective observational study.

SETTING

Medical ICU in a tertiary teaching hospital.

PATIENTS

To assess the relationship between metabolic acidosis severity and microvascular reactivity, we included adult diabetic patients admitted in ICU for ketoacidosis. Microvascular response to acetylcholine iontophoresis was measured at admission (baseline) and after correction of metabolic acidosis (24 hr).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Thirty-nine patients with diabetic ketoacidosis were included (68% male), with a median age of 43 (31-57) years. At admission, microvascular reactivity negatively correlated with acidosis severity (R = -0.53; p < 0.001). Microvascular response was strongly depressed at pH less than 7.20 (area under the curve, 1,779 [740-3,079] vs 12,944 [4,874-21,596] at pH > 7.20; p < 0.0001). In addition, acidosis severity was significantly correlated with capillary refill time (R = 0.50; p = 0.02). At H24, after rehydration and insulin infusion, clinical and biological disorders were fully corrected. After acidosis correction, microvascular reactivity increased more in patients with severe baseline acidosis (pH < 7.20) than in those with mild baseline acidosis (area under the curve, +453% [213%-1,470%] vs +121% [79%-312%]; p < 0.01).

CONCLUSIONS

We identified an alteration of microvascular reactivity during metabolic acidosis in critically ill patients with diabetic ketoacidosis. Microvascular hyporeactivity recovered after acidosis correction.

Association of endothelial and glycocalyx injury biomarkers with fluid administration, development of acute kidney injury, and 90-day mortality: data from the FINNAKI observational study

Background

Injury to endothelium and glycocalyx predisposes to vascular leak, which may subsequently lead to increased fluid requirements and worse outcomes. In this post hoc study of the prospective multicenter observational Finnish Acute Kidney Injury (FINNAKI) cohort study conducted in 17 Finnish intensive care units, we studied the association of Syndecan-1 (SDC-1), Angiopoetin-2 (Ang-2), soluble thrombomodulin (sTM), vascular adhesion protein-1 (VAP-1) and interleukin-6 (IL-6) with fluid administration and balance among septic critical care patients and their association with development of acute kidney injury (AKI) and 90-day mortality.

Results

SDC-1, Ang-2, sTM, VAP-1 and IL-6 levels were measured at ICU admission from 619 patients with sepsis. VAP-1 decreased (p < 0.001) and IL-6 increased (p < 0.001) with increasing amounts of administered fluid, but other biomarkers did not show differences according to fluid administration. In linear regression models adjusted for IL-6, only VAP-1 was significantly associated with fluid administration on day 1 (p < 0.001) and the cumulative fluid balance on day 5/ICU discharge (p = 0.001). Of 415 patients admitted without AKI, altogether 112 patients (27.0%) developed AKI > 12 h from ICU admission (AKI_>12 h). They had higher sTM levels than patients without AKI, and after multivariable adjustment log, sTM level was associated with AKI_>12 h with OR (95% CI) of 12.71 (2.96–54.67), p = 0.001). Ninety-day non-survivors (n = 180; 29.1%) had higher SDC-1 and sTM levels compared to survivors. After adjustment for known confounders, log SDC-1 (OR [95% CI] 2.13 [1.31–3.49], p = 0.002), log sTM (OR [95% CI] 7.35 [2.29–23.57], p < 0.001), and log Ang-2 (OR [95% CI] 2.47 [1.44–4.14], p = 0.001) associated with an increased risk for 90-day mortality. Finally, patients who had high levels of all three markers, namely, SDC-1, Ang-2 and sTM, had an adjusted OR of 5.61 (95% CI 2.67–11.79; p < 0.001) for 90-day mortality.

Conclusions

VAP-1 and IL-6 associated with fluid administration on the first ICU day. After adjusting for confounders, sTM was associated with development of AKI after 12 h from ICU admission. SDC-1, Ang-2 and sTM were independently associated with an increased risk for 90-day mortality.