Regulatory mechanisms, prophylaxis and treatment of vascular leakage following severe trauma and shock

Determination of Endothelial Barrier Resistance by Electric Cell-Substrate Impedance Sensing (ECIS) System

Endothelial cells lining the inner surface of blood vessels and lymphatic vessels play an indispensable role in vascular homeostasis. Apart from regulating vessel tone and forming an anti-thrombotic and anti-atherosclerotic surface, the dynamic endothelial barrier controls transport of solutes and fluid in and out of tissues at the capillary bed. Transit of circulating leukocytes into and out of circulation during inflammation and tissue repair is also regulated by the endothelium. Dysregulation of this barrier function of endothelial cells is a hallmark feature of multiple diseases and conditions such as sepsis, cancer metastasis, and edema. In this chapter we describe a detailed methodology to perform an in vitro experiment to monitor changes in barrier properties of human umbilical vein endothelial cells (HUVECs) in real time, in response to thrombin with electrical cell-substrate impedance sensing (ECIS) biosensor system.

Capillary leak and endothelial permeability in critically ill patients: a current overview

Capillary leak syndrome (CLS) represents a phenotype of increased fluid extravasation, resulting in intravascular hypovolemia, extravascular edema formation and ultimately hypoperfusion. While endothelial permeability is an evolutionary preserved physiological process needed to sustain life, excessive fluid leak-often caused by systemic inflammation-can have detrimental effects on patients' outcomes. This article delves into the current understanding of CLS pathophysiology, diagnosis and potential treatments. Systemic inflammation leading to a compromise of endothelial cell interactions through various signaling cues (e.g., the angiopoietin-Tie2 pathway), and shedding of the glycocalyx collectively contribute to the manifestation of CLS. Capillary permeability subsequently leads to the seepage of protein-rich fluid into the interstitial space. Recent insights into the importance of the sub-glycocalyx space and preserving lymphatic flow are highlighted for an in-depth understanding. While no established diagnostic criteria exist and CLS is frequently diagnosed by clinical characteristics only, we highlight more objective serological and (non)-invasive measurements that hint towards a CLS phenotype. While currently available treatment options are limited, we further review understanding of fluid resuscitation and experimental approaches to target endothelial permeability. Despite the improved understanding of CLS pathophysiology, efforts are needed to develop uniform diagnostic criteria, associate clinical consequences to these criteria, and delineate treatment options.

Pilot randomized controlled trial of restricted versus liberal crystalloid fluid management in pediatric post-operative and trauma patients

BACKGROUND

Intravenous (IV) fluid therapy is essential in the treatment of critically ill pediatric surgery and trauma patients. Recent studies have suggested that aggressive fluids may be detrimental to patients. Prospective studies are needed to compare liberal to restricted fluid management in these patients. The primary objective of this pilot trial is to test study feasibility-recruitment and adherence to the study treatment algorithm.

METHODS

We conducted a two-part pilot randomized controlled trial (RCT) comparing liberal to restricted crystalloid fluid management in 50 pediatric post-operative (1-18 years) and trauma (1-15 years) patients admitted to our pediatric intensive care unit (PICU). Patients were randomized to a high (liberal) volume or low (restricted) volume algorithm using unblinded, blocked randomization. A revised treatment algorithm was used after the 29th patient for the second part of the RCT. The goal of the trial was to determine the feasibility of conducting an RCT at a single site for recruitment and retention. We also collected data on the safety of study interventions and clinical outcomes, including pulmonary, infectious, renal, post-operative, and length of stay outcomes.

RESULTS

Fifty patients were randomized to either liberal (n = 26) or restricted (n = 24) fluid management strategy. After data was obtained on 29 patients, a first study analysis was performed. The volume of fluid administered and triggers for intervention were adapted to optimize the treatment effect and clarity of outcomes. Updated and refined fluid management algorithms were created. These were used for the second part of the RCT on patients 30-50. During this second study period, 54% (21/39, 95% CI 37-70%) of patients approached were enrolled in the study. Of the patients enrolled, 71% (15/21, 95% CI 48-89%) completed the study. This met our a priori recruitment and retention criteria for success. A data safety monitoring committee concluded that no adverse events were related to study interventions. Although the study was not powered to detect differences in outcomes, after the algorithm was revised, we observed a non-significant trend towards improved pulmonary outcomes in patients on the restricted arm, including decreased need for and time on oxygen support and decreased need for mechanical ventilation.

CONCLUSION

We demonstrated the feasibility and safety of conducting a single-site RCT comparing liberal to restricted crystalloid fluid management in critically ill pediatric post-operative and trauma patients. We observed trends in improved pulmonary outcomes in patients undergoing restricted fluid management. A definitive multicenter RCT comparing fluid management strategies in these patients is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04201704 . Registered 17 December 2019-retrospectively registered.

Effect of miR-21-3p on lung injury in rats with traumatic hemorrhagic shock resuscitated with sodium bicarbonate Ringer's solution

Background

Restricted fluid resuscitation is the most important early method for treating traumatic hemorrhagic shock (THS). This study sought to explore whether micro ribonucleic acid (miR)-21-3p affected resuscitated THS rats by regulating the glycocalyx and inflammation.

Methods

MiRNAs extracted from the lung tissues were analyzed by miRNA microarray assays. A rat model of THS was induced by hemorrhage from a left femur fracture. The pathological change in the lung tissues and glycocalyx structure was observed by hematoxylin and eosin staining and a transmission electron microscope examination. The miR-21-3p expression in the lung tissues and serum was detected by real-time quantitative polymerase chain reaction (RT-qPCR). The levels of glycocalyx-related factors and inflammation-related factors were determined by enzyme linked immunosorbent assays. The expression of glycocalyx-related proteins, cell junction-related proteins, and the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/nuclear factor kappa B (NF-κB) signaling pathway-related proteins was analyzed by Western blot.

Results

After RT-qPCR verification, the variation trend of miR-21-3p was in line with expected trends. The mean arterial pressure (MAP) and heart rate (HR) were decreased, and the lung injury and damage to the glycocalyx were all aggravated in the THS rats resuscitated with sodium bicarbonate Ringer's solution (BRS) or sodium lactate Ringer's solution (LRS). The expression of miR-21-3p was decreased in the THS rats resuscitated with BRS and increased in the THS rats resuscitated with LRS, and the upregulation of miR-21-3p further decreased the MAP and HR, and increased the levels of syndecan-1 (SDC-1), heparanase-1 (HPA1), interleukin (IL)-6, IL-1β, and tumor necrosis factor alpha (TNF-α) in the serum of the THS rats resuscitated with BRS. The upregulation of miR-21-3p also increased the expression of SDC-1, HPA1, β-catenin, matrix metallopeptidase (MMP)2, and MMP9, but decreased the expression of E-cadherin (E-cad) and activated the PI3K/Akt/NF-κB signaling pathway in the THS rats resuscitated with BRS and transfected with miR-21-3p compared to that of the THS rats resuscitated with BRS and transfected with miR-negative control (NC).

Conclusions

miR-21-3p promoted inflammation and glycocalyx damage by activating the PI3K/Akt/NF-κB signaling pathway, thereby aggravating the lung injury in the THS rats resuscitated with BRS.

The protective effect of pericytes on vascular permeability after hemorrhagic shock and their relationship with Cx43

Vascular hyperpermeability is a complication of hemorrhagic shock. Pericytes (PCs) are a group of mural cells surrounded by microvessels that are located on the basolateral side of the endothelium. Previous studies have shown that damage to PCs contributes to the occurrence of many diseases such as diabetic retinopathy and myocardial infarction. Whether PCs can protect the vascular barrier function following hemorrhagic shock and the underlying mechanisms are unknown. A hemorrhagic shock rat model, Cx43 vascular endothelial cell (VEC)-specific knockdown mice, and VECs were used to investigate the role of PCs in vascular barrier function and their relationship with Cx43. The results showed that following hemorrhagic shock, the number of PCs in the microvessels was significantly decreased and was negatively associated with an increase in pulmonary and mesenteric vascular permeability. Exogenous infusion of PCs (106 cells per rat) colonized the microvessels and improved pulmonary and mesenteric vascular barrier function. Upregulation of Cx43 in PCs significantly increased the number of PCs colonizing the pulmonary vessels. In contrast, downregulation of Cx43 expression in PCs or knockout of Cx43 in VECs (Cx43 KO mice) significantly reduced PC colonization in pulmonary vessels in vivo and reduced direct contact formation between PCs and VECs in vitro. It has been suggested that PCs have an important protective effect on vascular barrier function in pulmonary and peripheral vessels following hemorrhagic shock. Cx43 plays an important role in the colonization of exogenous PCs in the microvessels. This finding provides a potential new shock treatment measure.

Trauma-induced capillary leak syndrome after penetrating chest injury: Manifestation of massive ascites and pulmonary secretions aggravated by transfusion

Trauma with prolonged shock can cause systemic capillary leak syndrome regardless of the site of injury and a transfusion can aggravate it. The systemic capillary leak induces both an abdominal compartment syndrome and pulmonary edema, and a transfusion can aggra-vate these sequelae within hours. In our case, 21-year-old man with a penetrating injury in his left thorax experienced delay in rescue and definitive surgery. To manage life-threatening shock, massive blood transfusion and crystalloids had been infused. Cardiopulmonary cerebral resuscitations were performed 2 times during the surgery. Massive amount of pulmonary secretions emitted from his airways with severe hypoxia along with development of massive ascites causing abdominal compartment syndrome, while the surgery was underway. After temporary abdominal closure, he was moved to the intensive care unit and underwent venovenous extracorporeal membranous oxygenation. He recovered without any notable complications. It is important to prevent and correct the shock rapidly by appropriate rescue, controlling the source and infusing less amount of crystalloid and transfusion.

Effect of Change in Body Weight on Clinical Outcomes in Critically Ill Patients

Background

Intravenous fluid optimization is an essential component of managing patients in a critical care setting. A cumulative positive fluid balance is consistent with poor outcomes in patients admitted to the intensive care unit (ICU). The overall utility of net cumulative fluid balance as a surrogate for assessing fluid overload has been interrogated.

Materials and methods

This study was a prospective single-center observational study, which was done to correlate body weight changes with fluid balance in ICU patients and evaluate its impact on clinical outcomes. Inclusion criteria consisted of adult patients who were admitted to the critical care unit on specialized beds with integrated weighing scales between September 2017 and December 2018. The evaluation of the effect of changes in body weight on ICU survival was the primary objective of the study.

Results

We enrolled 105 patients in this study. The ICU mortality was 23.80% with non-survivors showing more weight gain than the survivors. Statistically significant weight gain was documented in the non-survivors on days 3 and 4 (1.9 vs 1.05; p = 0.0084 and 2.6 vs 1.6; p = 0.0030) of ICU admission. Non-survivors had greater cumulative positive fluid balance on fourth, fifth, and sixth days post-ICU admission when compared to survivors (3586 vs 1659 mL, p = 0.0322; 5418 vs 1255 mL, p = 0.0017; and 5430 vs 2305 mL p = 0.0264, respectively). In multivariate regression analysis, cumulative fluid balance did not correlate with days on mechanical ventilation or length of stay in ICU. Changes in body weight and cumulative fluid balance showed a good correlation.

Conclusion

In patients admitted to the ICU, weight gain on third and fourth days of admission is concordant with increased ICU mortality. Body weight changes were seen to correlate well with the cumulative fluid balance.

How to cite this article

Mishra RK, Pande A, Ramachandran R, Trikha A, Singh PM, Rewari V. Effect of Change in Body Weight on Clinical Outcomes in Critically Ill Patients. Indian J Crit Care Med 2021;25(9):1042–1048.

Continuous renal replacement therapy rescued life-threatening capillary leak syndrome in an extremely-low-birth-weight premature: a case report

BACKGROUND

Capillary leak syndrome (CLS) is a rare disease characterized by profound vascular leakage and presents as a classic triad of hypotension, hypoalbuminemia and hemoconcentration. Severe CLS is mostly induced by sepsis and generally life-threatening in newborns, especially in premature infants. Continuous renal replacement therapy (CRRT) plays an important role of supportive treatment for severe CLS. Unfortunately, CRRT in preterm infants has rarely been well defined.

CASE PRESENTATION

We report the case of a 11-day-old girl with CLS caused by sepsis, who was delivered by spontaneous vaginal delivery (SVD) at gestational age of 25 weeks and 4 days, and a birth weight of 0.89 Kilograms(kg). The infant received powerful management consisting of united antibiotics, mechanical ventilation, intravenous albumin and hydroxyethyl starch infusion, vasoactive agents, small doses of glucocorticoids and other supportive treatments. However, the condition rapidly worsened with systemic edema, hypotension, pulmonary exudation, hypoxemia and anuria in about 40 h. Finally, we made great efforts to perform CRRT for her. Fortunately, the condition improved after 82 h' CRRT, and the newborn was rescued and gradually recovered.

CONCLUSION

CRRT is an effective rescue therapeutic option for severe CLS and can be successfully applied even in extremely-low-birth-weight premature.

Protective Effects of Dexmedetomidine on the Vascular Endothelial Barrier Function by Inhibiting Mitochondrial Fission via ER/Mitochondria Contact

The damage of vascular endothelial barrier function induced by sepsis is critical in causing multiple organ dysfunctions. Previous studies showed that dexmedetomidine (Dex) played a vital role in protecting organ functions. However, whether Dex participates in protecting vascular leakage of sepsis and the associated underlying mechanism remains unknown yet. We used cecal ligation and puncture induced septic rats and lipopolysaccharide stimulated vascular endothelial cells (VECs) to establish models in vivo and in vitro, then the protective effects of Dex on the vascular endothelial barrier function of sepsis were observed, meanwhile, related mechanisms on regulating mitochondrial fission were further studied. The results showed that Dex could significantly reduce the permeability of pulmonary veins and mesenteric vessels, increase the expression of intercellular junction proteins, enhance the transendothelial electrical resistance and decrease the transmittance of VECs, accordingly protected organ functions and prolonged survival time in septic rats. Besides, the mitochondria of VECs were excessive division after sepsis, while Dex could significantly inhibit the mitochondrial fission and protect mitochondrial function by restoring mitochondrial morphology of VECs. Furthermore, the results showed that ER-MITO contact sites of VECs were notably increased after sepsis. Nevertheless, Dex reduced ER-MITO contact sites by regulating the polymerization of actin via α₂ receptors. The results also found that Dex could induce the phosphorylation of the dynamin-related protein 1 through down-regulating extracellular signal-regulated kinase1/2, thus playing a role in the regulation of mitochondrial division. In conclusion, Dex has a protective effect on the vascular endothelial barrier function of septic rats. The mechanism is mainly related to the regulation of Drp1 phosphorylation of VECs, inhibition of mitochondrial division by ER-MITO contacts, and protection of mitochondrial function.

In vitro endothelial hyperpermeability occurs early following traumatic hemorrhagic shock

BACKGROUND

Endothelial hyperpermeability is suggested to play a role in the development of microcirculatory perfusion disturbances and organ failure following hemorrhagic shock, but evidence is limited.

OBJECTIVE

To study the effect of plasma from traumatic hemorrhagic shock patients on in vitro endothelial barrier function.

METHODS

Plasma from traumatic hemorrhagic shock patients was obtained at the emergency department (ED), the intensive care unit (ICU), 24 h after ICU admission and from controls (n = 8). Sublingual microcirculatory perfusion was measured using incident dark field videomicroscopy at matching time points. Using electric cell-substrate impedance sensing, the effects of plasma exposure on in vitro endothelial barrier function of human endothelial cells were assessed.

RESULTS

Plasma from traumatic hemorrhagic shock patients collected at ED admission induced a 19% loss of in vitro endothelial resistance compared to plasma from controls (p < 0.001). This loss was due to reduced cell-cell contacts (p < 0.01). Plasma withdrawn at later time points did not affect endothelial barrier function (p > 0.99). Interestingly, in vitro endothelial resistance showed a positive association with in vivo microcirculatory perfusion (r = 0.56, p < 0.01).

CONCLUSIONS

Plasma from traumatic hemorrhagic shock patients obtained following ED admission, but not at later stages, induced in vitro endothelial hyperpermeability. This coincided with in vivo microcirculatory perfusion disturbances.

The Beneficial Effect of HES on Vascular Permeability and Its Relationship With Endothelial Glycocalyx and Intercellular Junction After Hemorrhagic Shock

Background

Vascular leakage is a common complication of hemorrhagic shock. Endothelial glycocalyx plays a crucial role in the protection of vascular endothelial barrier function. Hydroxyethyl starch (HES) is a commonly used resuscitation fluid for hemorrhagic shock. However, whether the protective effect of HES on vascular permeability after hemorrhagic shock is associated with the endothelial glycocalyx is unclear.

Methods

Using hemorrhagic shock rat model and hypoxia treated vascular endothelial cells (VECs), effects of HES (130/0.4) on pulmonary vascular permeability and the relationship to endothelial glycocalyx were observed.

Results

Pulmonary vascular permeability was significantly increased after hemorrhagic shock, as evidenced by the increased permeability of pulmonary vessels to albumin-fluorescein isothiocyanate conjugate (FITC-BSA) and Evans blue, the decreased transendothelial electrical resistance of VECs and the increased transmittance of FITC-BSA. The structure of the endothelial glycocalyx was destroyed, showing a decrease in thickness. The expression of heparan sulfate, hyaluronic acid, and chondroitin sulfate, the components of the endothelial glycocalyx, was significantly decreased. HES (130/0.4) significantly improved the vascular barrier function, recovered the thickness and the expression of components of the endothelial glycocalyx by down-regulating the expression of heparinase, hyaluronidase, and neuraminidase, and meanwhile increased the expression of intercellular junction proteins ZO-1, occludin, and VE-cadherin. Degradation of endothelial glycocalyx with degrading enzyme (heparinase, hyaluronidase, and neuraminidase) abolished the beneficial effect of HES on vascular permeability, but had no significant effect on the recovery of the expression of endothelial intercellular junction proteins induced by HES (130/0.4). HES (130/0.4) decreased the expression of cleaved-caspase-3 induced by hemorrhagic shock.

Conclusions

HES (130/0.4) has protective effect on vascular barrier function after hemorrgic shock.The mechanism is mainly related to the protective effect of HES on endothelial glycocalyx and intercellular junction proteins. The protective effect of HES on endothelial glycocalyx was associated with the down-regulated expression of heparinase, hyaluronidase, and neuraminidase. HES (130/0.4) had an anti-apoptotic effect in hemorrhagic shock.

Drp1 regulates mitochondrial dysfunction and dysregulated metabolism in ischemic injury via Clec16a-, BAX-, and GSH- pathways

The adaptation of mitochondrial homeostasis to ischemic injury is not fully understood. Here, we studied the role of dynamin-related protein 1 (Drp1) in this process. We found that mitochondrial morphology was altered in the early stage of ischemic injury while mitochondrial dysfunction occurred in the late stage of ischemia. Drp1 appeared to inhibit mitophagy by upregulating mito-Clec16a, which suppressed mito-Parkin recruitment and subsequently impaired the formation of autophagosomes in vascular tissues after ischemic injury. Moreover, ischemia-induced Drp1 activation enhanced apoptosis through inducing mitochondrial translocation of BAX and thereby increasing release of Cytochrome C to activate caspase-3/-9 signalling. Furthermore, Drp1 mediated metabolic disorders and inhibited the levels of mitochondrial glutathione to impair free radical scavenging, leading to further increases in ROS and the exacerbation of mitochondrial dysfunction after ischemic injury. Together, our data suggest a critical role for Drp1 in ischemic injury.

Rapid changes in the microvascular circulation of skeletal muscle impair insulin delivery during sepsis

Sepsis costs the healthcare system $23 billion annually and has a mortality rate between 10 and 40%. An early indication of sepsis is the onset of hyperglycemia, which is the result of sepsis-induced insulin resistance in skeletal muscle. Previous investigations have focused on events in the myocyte (e.g., insulin signaling and glucose transport and subsequent metabolism) as the causes for this insulin-resistant state. However, the delivery of insulin to the skeletal muscle is also an important determinant of insulin action. Skeletal muscle microvascular blood flow, which delivers the insulin to the muscle, is known to be decreased during sepsis. Here we test whether the reduced capillary blood flow to skeletal muscle belies the sepsis-induced insulin resistance by reducing insulin delivery to the myocyte. We hypothesize that decreased capillary flow and consequent decrease in insulin delivery is an early event that precedes gross cardiovascular alterations seen with sepsis. This hypothesis was examined in mice treated with either lipopolysaccharide (LPS) or polymicrobial sepsis followed by intravital microscopy of the skeletal muscle microcirculation. We calculated insulin delivery to the myocyte using two independent methods and found that LPS and sepsis rapidly reduce insulin delivery to the skeletal muscle by ~50%; this was driven by decreases in capillary flow velocity and the number of perfused capillaries. Furthermore, the changes in skeletal muscle microcirculation occur before changes in both cardiac output and arterial blood pressure. These data suggest that a rapid reduction in skeletal muscle insulin delivery contributes to the induction of insulin resistance during sepsis.

Effect of ERK inhibitor on corneal neovascularization induced by alkali burn in mice and its mechanism

The objective of this study is to explore the effect of extracellular signal–regulated kinase (ERK) inhibitors on corneal neovascularization induced by alkali burn in mice and its mechanism. A total of 30 standard diet (SD) healthy mice were divided into normal group, alkali burn group, and inhibitor group. Normal group was not treated. Alkali burn group and inhibitor group were used to establish corneal neovascularization model induced by alkali burn. After successful modeling, ERK inhibitor was used to intervene in inhibitor group, and saline of equal volume was used in normal group and alkali burn group. The area of corneal neovascularization was calculated and the expression of vascular endothelial growth factor (VEGF), c-Fos, c-Jun, ERK1/2, and p-ERK1/2 protein in cornea tissue of three groups of mice was detected. The relative expression of vascular area, length, VEGF, c-Fos, c-Jun, ERK1/2, and p-ERK1/2 protein in cornea tissue of mice in alkali burn group was significantly higher than that in normal group and inhibitor group. The relative expression of vascular area, length, VEGF, c-Fos, c-Jun, ERK1/2, and p-ERK1/2 protein in cornea tissue of mice in inhibitor group was higher than that in normal group, and the expression level of PEDF was lower than that in normal group ( P < 0.05). ERK inhibitors inhibit the formation of corneal neovascularization by inhibiting the expression of VEGF, c-Fos, and c-Jun proteins through the action of ERK signaling pathway.