Sevoflurane did not show better protective effect on endothelial glycocalyx layer compared to propofol during lung resection surgery with one lung ventilation

Sedation with propofol and isoflurane differs in terms of microcirculatory parameters: A randomized animal study using dorsal skinfold chamber mouse model

OBJECTIVE

This study aimed to explore the effects of sedative doses of propofol and isoflurane on microcirculation in septic mice compared to controls. Isoflurane, known for its potential as a sedation drug in bedside applications, lacks clarity regarding its impact on the microcirculation system. The hypothesis was that propofol would exert a more pronounced influence on the microvascular flow index, particularly amplified in septic conditions.

MATERIAL AND METHODS

Randomized study was conducted from December 2020 to October 2021 involved 60 BALB/c mice, with 52 mice analyzed. Dorsal skinfold chambers were implanted, followed by intraperitoneal injections of either sterile 0.9 % saline or lipopolysaccharide for the control and sepsis groups, respectively. Both groups received propofol or isoflurane treatment for 120 min. Microcirculatory parameters were obtained via incident dark-field microscopy videos, along with the mean blood pressure and heart rate at three time points: before sedation (T0), 30 min after sedation (T30), and 120 min after sedation (T120). Endothelial glycocalyx thickness and syndecan-1 concentration were also analyzed.

RESULTS

In healthy controls, both anesthetics reduced blood pressure. However, propofol maintained microvascular flow, differing significantly from isoflurane at T120 (propofol, 2.8 ± 0.3 vs. isoflurane, 1.6 ± 0.9; P < 0.001). In the sepsis group, a similar pattern occurred at T120 without statistical significance (propofol, 1.8 ± 1.1 vs. isoflurane, 1.2 ± 0.7; P = 0.023). Syndecan-1 levels did not differ between agents, but glycocalyx thickness index was significantly lower in the isoflurane-sepsis group than propofol (P = 0.001).

CONCLUSIONS

Propofol potentially offers protective action against microvascular flow deterioration compared to isoflurane, observed in control mice. Furthermore, a lower degree of sepsis-induced glycocalyx degradation was evident with propofol compared to isoflurane.

Insights into the Molecular Mechanism of Endothelial Glycocalyx Dysfunction during Heart Surgery

The endothelial glycocalyx (EGC) is a layer of proteoglycans (associated with glycosaminoglycans) and glycoproteins, which adsorbs plasma proteins on the luminal surface of endothelial cells. Its main function is to participate in separating the circulating blood from the inner layers of the vessels and the surrounding tissues. Physiologically, the EGC stimulates mechanotransduction, the endothelial charge, thrombocyte adhesion, leukocyte tissue recruitment, and molecule extravasation. Hence, severe impairment of the EGC has been implicated in various pathological conditions, including sepsis, diabetes, chronic kidney disease, inflammatory disorders, hypernatremia, hypervolemia, atherosclerosis, and ischemia/reperfusion injury. Moreover, alterations in EGC have been associated with altered responses to therapeutic interventions in conditions such as cardiovascular diseases. Investigation into the function of the glycocalyx has expanded knowledge about vascular disorders and indicated the need to consider new approaches in the treatment of severe endothelial dysfunction. This review aims to present the current understanding of the molecular mechanisms underlying cardiovascular diseases and to elucidate the impact of heart surgery on EGC dysfunction.

The endothelium: gatekeeper to lung ischemia-reperfusion injury

The success of lung transplantation is limited by the high rate of primary graft dysfunction due to ischemia-reperfusion injury (IRI). Lung IRI is characterized by a robust inflammatory response, lung dysfunction, endothelial barrier disruption, oxidative stress, vascular permeability, edema, and neutrophil infiltration. These events are dependent on the health of the endothelium, which is a primary target of IRI that results in pulmonary endothelial barrier dysfunction. Over the past 10 years, research has focused more on the endothelium, which is beginning to unravel the multi-factorial pathogenesis and immunologic mechanisms underlying IRI. Many important proteins, receptors, and signaling pathways that are involved in the pathogenesis of endothelial dysfunction after IR are starting to be identified and targeted as prospective therapies for lung IRI. In this review, we highlight the more significant mediators of IRI-induced endothelial dysfunction discovered over the past decade including the extracellular glycocalyx, endothelial ion channels, purinergic receptors, kinases, and integrins. While there are no definitive clinical therapies currently available to prevent lung IRI, we will discuss potential clinical strategies for targeting the endothelium for the treatment or prevention of IRI. The accruing evidence on the essential role the endothelium plays in lung IRI suggests that promising endothelial-directed treatments may be approaching the clinic soon. The application of therapies targeting the pulmonary endothelium may help to halt this rapid and potentially fatal injury.

Cerebrovascular glycocalyx damage and microcirculation impairment in patients with temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is increasingly associated with blood-brain barrier dysfunction and microvascular alterations, yet the pathophysiological link is missing. An important barrier function is exerted by the glycocalyx, a gel-like layer coating the endothelium. To explore such associations, we used intraoperative videomicroscopy to quantify glycocalyx and microcirculation properties of the neocortex and hippocampus of 15 patients undergoing resective brain surgery as treatment for drug-resistant TLE, and 15 non-epileptic controls. Fluorescent lectin staining of neocortex and hippocampal tissue was used for blood vessel surface area quantification. Neocortical perfused boundary region, the thickness of the glycocalyx' impaired layer, was higher in patients (2.64 ± 0.52 µm) compared to controls (1.31 ± 0.29 µm), P < 0.01, indicative of reduced glycocalyx integrity in patients. Moreover, erythrocyte flow velocity analysis revealed an impaired ability of TLE patients to (de-)recruit capillaries in response to changing metabolic demands (R2 = 0.75, P < 0.01), indicating failure of neurovascular coupling mechanisms. Blood vessel quantification comparison between intraoperative measurements and resected tissue showed strong correlation (R2 = 0.94, P < 0.01). This is the first report on in vivo assessment of glycocalyx and microcirculation properties in TLE patients, confirming the pivotal role of cerebrovascular changes. Further assessment of the cerebral microcirculation in relation to epileptogenesis might open avenues for new therapeutic targets for drug-resistant epilepsy.

Immediate Postoperative High Syndecan-1 is Associated with Short-Term Morbidity and Mortality After Robot-Assisted Esophagectomy: A Prospective Observational Study

BACKGROUND

Disruption of the endothelial glycocalyx (EG) is associated with a poor prognosis in various clinical settings. This study aimed to determine the association between immediate postoperative serum syndecan-1 levels, a representative marker for EG degradation, and major postoperative morbidity and mortality in patients undergoing robot-assisted esophagectomy.

METHODS

Patients who underwent robot-assisted esophagectomy between 2018 and 2022 were prospectively enrolled. The primary outcome was the association between immediate postoperative syndecan-1 levels and the occurrence of major postoperative morbidity and mortality within 30 days of surgery. Patients were classified into low and high syndecan-1 groups based on the optimal cut-off value of syndecan-1 for predicting major morbidity and mortality. A multivariable logistic regression analysis was performed to investigate the risk factors for major morbidity and mortality.

RESULTS

A total of 207 patients were analyzed. Patients with high syndecan-1 levels (≥48 ng/mL) showed a significantly greater incidence of unexpected returns to the operating room and anastomotic leaks and longer durations of hospital and intensive care unit stays than patients with low syndecan-1 levels (<48 ng/mL). Immediate postoperative syndecan-1 levels ≥48 ng/mL (odds ratio [OR] 2.32, 95% confidence interval [CI] 1.23-4.76), American Society of Anesthesiologists physical status ≥III (OR 3.36, 95% CI 1.56-7.22), and current smoker (OR 4.02, 95% CI 1.52-10.61) were independently associated with major morbidity and mortality within 30 days of esophagectomy.

CONCLUSIONS

Immediate postoperative syndecan-1 levels ≥48 ng/mL could be used for the early detection of patients at high risk of complications after robot-assisted esophagectomy.

Endothelial Dysfunction in Patients Undergoing Cardiac Surgery: A Narrative Review and Clinical Implications

Cardiac surgery is one of the highest-risk procedures, usually involving cardiopulmonary bypass and commonly inducing endothelial injury that contributes to the development of perioperative and postoperative organ dysfunction. Substantial scientific efforts are being made to unravel the complex interaction of biomolecules involved in endothelial dysfunction to find new therapeutic targets and biomarkers and to develop therapeutic strategies to protect and restore the endothelium. This review highlights the current state-of-the-art knowledge on the structure and function of the endothelial glycocalyx and mechanisms of endothelial glycocalyx shedding in cardiac surgery. Particular emphasis is placed on potential strategies to protect and restore the endothelial glycocalyx in cardiac surgery. In addition, we have summarized and elaborated the latest evidence on conventional and potential biomarkers of endothelial dysfunction to provide a comprehensive synthesis of crucial mechanisms of endothelial dysfunction in patients undergoing cardiac surgery, and to highlight their clinical implications.

Effect of sevoflurane-remifentanil and propofol-remifentanil anesthesia on glycocalyx shedding during deep inferior epigastric perforator flap breast reconstruction: a prospective randomized, controlled trial

BACKGROUND

The endothelial glycocalyx (EG) is an important structure that regulates vascular homeostasis. Deep inferior epigastric perforator (DIEP) flap is expected to cause substantial EG breakdown owing to the long procedural duration and ischemia- reperfusion injury. This prospective, randomized, controlled study aimed to compare syndecan-1 levels during sevoflurane-remifentanil and propofol-remifentanil anesthesia in patients who underwent DIEP flap breast reconstruction.

METHODS

Fifty-one patients were randomized to either sevoflurane (n = 26) or propofol (n = 25) groups. Anesthesia was maintained with remifentanil in combination with either sevoflurane or propofol. The primary endpoint was the concentration of serum syndecan-1 measured at 1 h after surgery.

RESULTS

Fifty patients (98.0%) completed the study. Patients in the propofol group had significantly lower levels of syndecan-1 than patients in the sevoflurane group at 1 h after operation (23.8 ± 1.6 vs. 30.9 ± 1.7 ng/ml, respectively; Bonferroni corrected P = 0.012). There were no significant differences between groups in postoperative complications. The postoperative hospital stay was 8.4 ± 2.5 days in the sevoflurane group and 7.4 ± 1.0 days in the propofol group (P = 0.077).

CONCLUSIONS

Propofol-remifentanil anesthesia resulted in lesser increases in syndecan-1 levels compared to increases with sevoflurane-remifentanil anesthesia in patients who underwent DIEP flap reconstruction. Our results suggest that propofol-remifentanil anesthesia shows protective effects against EG damage during DIEP flap breast reconstruction in contrast to sevoflurane-remifentanil anesthesia.

General anaesthesia with double-lumen intubation compared to opioid-sparing strategies with laryngeal mask for thoracoscopic surgery: A randomised trial

BACKGROUND

General anaesthesia for thoracoscopic lung surgery can be performed with the opioid-sparing strategies without intubation and may reduce the risk of glottic injury and enhance recovery after surgery. We therefore tested the primary hypothesis that avoiding intubation reduces glottic injury.

METHODS

Adults having elective thoracoscopic lung resections were randomised to: (1) intubated group: routine general anaesthesia with a double-lumen tube intubation; or, (2) non-intubated group: a bundle of opioid-sparing strategies, which included paravertebral blocks and total intravenous anaesthesia with minimal remifentanil infusion from 0.05 to 1.0 ng/mL (avoid sufentanil unless the respiratory rate exceeds 25/min or the systolic blood pressure exceeds 30% of the baseline value), no muscle relaxation, and spontaneous ventilation through a laryngeal mask. The primary outcome was glottal injury as determined by transnasal bronchoscopy one hour after removal of the laryngeal mask or double-lumen tube.

RESULTS

Two hundred seventeen patients were assessed for the primary outcome. Sufentanil use was reduced 96% and remifentanil was reduced 40% in non-intubated opioid-sparing patients. The incidence of glottal injury was 9% (10/109) in the non-intubated vs. 37% (40/108) in the intubated patients (RR: 0.25; 95%CI: 0.13-0.47, P < 0.001). The non-intubated group also had less postoperative sore throat (8% vs. 39%; P < 0.001) and hoarseness (3% vs. 19%; P < 0.001). Postoperative pulmonary complications and lung injury biomarkers did not differ between the groups. Compared to the intubated group, the non-intubated group had less postoperative pain, faster recovery, and improved quality-of-life scores.

CONCLUSIONS

Non-intubated opioid-sparing strategies for video-assisted lung resections reduce airway injury and promote postoperative recovery.

CLINICAL TRIAL NUMBER AND REGISTRY URL

ChiCTR1800018198 https://www.chictr.org.cn/showproj.aspx?proj=30780.

Restricted, optimized or liberal fluid strategy in thoracic surgery: A narrative review

Perioperative fluid balance has a major impact on clinical and functional outcome, regardless of the type of interventions. In thoracic surgery, patients are more vulnerable to intravenous fluid overload and to develop acute respiratory distress syndrome and other complications. New insight has been gained on the mechanisms causing pulmonary complications and the role of the endothelial glycocalix layer to control fluid transfer from the intravascular to the interstitial spaces and to promote tissue blood flow. With the implementation of standardized processes of care, the preoperative fasting period has become shorter, surgical approaches are less invasive and patients are allowed to resume oral intake shortly after surgery. Intraoperatively, body fluid homeostasis and adequate tissue oxygen delivery can be achieved using a normovolemic therapy targeting a “near-zero fluid balance” or a goal-directed hemodynamic therapy to maximize stroke volume and oxygen delivery according to the Franck–Starling relationship. In both fluid strategies, the use of cardiovascular drugs is advocated to counteract the anesthetic-induced vasorelaxation and maintain arterial pressure whereas fluid intake is limited to avoid cumulative fluid balance exceeding 1 liter and body weight gain (~1-1.5 kg). Modern hemodynamic monitors provide valuable physiological parameters to assess patient volume responsiveness and circulatory flow while guiding fluid administration and cardiovascular drug therapy. Given the lack of randomized clinical trials, controversial debate still surrounds the issues of the optimal fluid strategy and the type of fluids (crystalloids versus colloids). To avoid the risk of lung hydrostatic or inflammatory edema and to enhance the postoperative recovery process, fluid administration should be prescribed as any drug, adapted to the patient's requirement and the context of thoracic intervention.

Inhalational versus intravenous anesthetics during one lung ventilation in elective thoracic surgeries: A narrative review

The anesthesia regimen used during one lung ventilation (OLV) carry the potential to affect intra-operative course and post-operative outcomes, by its effects on pulmonary vasculature and alveolar inflammation. This narrative review aims to understand the pathophysiology of acute lung injury during one lung ventilation, and to study the effects of inhalational versus intravenous anaesthetics on intraoperative and post-operative outcomes, following thoracic surgery. For this purpose, we independently searched 'PubMed', 'Google Scholar' and 'Cochrane Central' databases to find out randomized controlled trials (RCTs), in English language, which compared the effects of intravenous versus inhalational anaesthetics on intraoperative and post-operative outcomes, in elective thoracic surgeries, in human beings. In total, 38 RCTs were included in this review. Salient results of the review are- Propofol reduced intraoperative shunt and maintained better intraoperative oxygenation than inhalational agents. However, use of modern inhalational anaesthetics during OLV reduced alveolar inflammation significantly, as compared to propofol. Regarding post-operative complications, the evidence is not conclusive enough but slightly in favour of inhalational anaesthetics. Thus, we conclude that modern inhalational anaesthetics, by their virtue of better anti-inflammatory properties, exhibit lung protective effects and hence, seem to be safe for maintenance of anesthesia during OLV in elective thoracic surgeries. Further research is required to establish the safety of these agents with respect to long term post-operative outcomes like cancer recurrence.

Sevoflurane protects the liver from ischemia-reperfusion injury by regulating Nrf2/HO-1 pathway

We aimed to investigate the role and mechanism of sevoflurane (SEV) preconditioning in liver ischemia-reperfusion (I/R) injury. In vivo, rats were randomly divided into Sham group, I/R rat model group, I/R + SEV group and SEV group. In vitro, hypoxia-reoxygenation (H/R) cell model were established. Hematoxylin-Eosin (H&E) and TUNEL assay were used to evaluate the degree of tissue damage and detect apoptosis in rats, respectively. HO-1, nuclear Nrf2 and cytosolic Nrf2 expressions were detected by immunohistochemical staining, Western blot analysis and quantitative real-time PCR (qRT-PCR), respectively. Contents of Lactate dehydrogenase (LDH), malondialdehyde (MDA), and reactive oxygen species (ROS) were determined by corresponding kits. Inflammatory factor levels, cell viability, apoptosis were detected by enzyme-linked immunosorbent assay (ELISA), MTT assay, and flow cytometry, respectively.In the I/R group, liver damage was severe, apoptosis-positive cells were increased, HO-1 and nuclear Nrf2 expressions were increased, and cytosolic Nrf2 expression was decreased. After SEV pretreatment, the degree of liver injury and apoptosis in rats were significantly reduced, HO-1 and nuclear Nrf2 expressions were increased significantly, and cytosolic Nrf2 expression was decreased. 4% SEV had the best mitigating effect on H/R-induced liver cell damage, as evidenced by reduced contents of LDH and MDA, decreased inflammatory factors, a lowered apoptosis rate, inhibited ROS production, effectively promoted Nrf2 nucleation, and activated Nrf/HO-1 pathway. ML385 pretreatment significantly inhibited the effect of SEV on hepatocytes.Sevoflurane protects the liver from ischemia-reperfusion injury by regulating the Nrf2/HO-1 pathway.

Human glycocalyx shedding: Systematic review and critical appraisal

BACKGROUND

The number of studies measuring breakdown products of the glycocalyx in plasma has increased rapidly during the past decade. The purpose of the present systematic review was to assess the current knowledge concerning the association between plasma concentrations of glycocalyx components and structural assessment of the endothelium.

METHODS

We performed a literature review of Pubmed to determine which glycocalyx components change in a wide variety of human diseases and conditions. We also searched for evidence of a relationship between plasma concentrations and the thickness of the endothelial glycocalyx layer as obtained by imaging methods.

RESULTS

Out of 3,454 publications, we identified 228 that met our inclusion criteria. The vast majority demonstrate an increase in plasma glycocalyx products. Sepsis and trauma are most frequently studied, and comprise approximately 40 publications. They usually report 3-4-foldt increased levels of glycocalyx degradation products, most commonly of syndecan-1. Surgery shows a variable picture. Cardiac surgery and transplantations are most likely to involve elevations of glycocalyx degradation products. Structural assessment using imaging methods show thinning of the endothelial glycocalyx layer in cardiovascular conditions and during major surgery, but thinning does not always correlate with the plasma concentrations of glycocalyx products. The few structural assessments performed do not currently support that capillary permeability is increased when the plasma levels of glycocalyx fragments in plasma are increased.

CONCLUSIONS

Shedding of glycocalyx components is a ubiquitous process that occurs during both acute and chronic inflammation with no sensitivity or specificity for a specific disease or condition.

The Endothelial Glycocalyx and Organ Preservation-From Physiology to Possible Clinical Implications for Solid Organ Transplantation

The endothelial glycocalyx is a thin layer consisting of proteoglycans, glycoproteins and glycosaminoglycans that lines the luminal side of vascular endothelial cells. It acts as a barrier and contributes to the maintenance of vascular homeostasis and microperfusion. During solid organ transplantation, the endothelial glycocalyx of the graft is damaged as part of Ischemia Reperfusion Injury (IRI), which is associated with impaired organ function. Although several substances are known to mitigate glycocalyx damage, it has not been possible to use these substances during graft storage on ice. Normothermic machine perfusion (NMP) emerges as an alternative technology for organ preservation and allows for organ evaluation, but also offers the possibility to treat and thus improve organ quality during storage. This review highlights the current knowledge on glycocalyx injury during organ transplantation, presents ways to protect the endothelial glycocalyx and discusses potential glycocalyx protection strategies during normothermic machine perfusion.

The Effect of Tranexamic Acid Administration on Early Endothelial Damage Following Posterior Lumbar Fusion Surgery

Tranexamic acid (TXA) protects against endothelial glycocalyx injury in vitro. We aimed to evaluate whether TXA could protect against endothelial glycocalyx degradation in patients undergoing posterior lumbar fusion surgery. Patients aged 30–80 years were enrolled. The TXA group was administered a loading dose of 10 mg/kg, followed by a 1 mg/kg/h infusion. Serum syndecan-1 and heparan sulfate concentrations, which are biomarkers of glycocalyx degradation, were measured at preoperative baseline (T0), immediately post-surgery (T1), and 2 h post-surgery (T2). Postoperative complications were assessed, including hypotension, desaturation, and acute kidney injury. Among the 121 patients who completed the study, 60 received TXA. There were no significant differences in the marker concentrations at each time point. However, the postoperative increase in syndecan-1 levels from baseline was significantly attenuated in the TXA group compared with the control group (median (interquartile range); T1 vs. T0: −1.6 (−5.3–2.6) vs. 2.2 (−0.7–4.8), p = 0.001; T2 vs. T0: 0.0 (−3.3–5.5) vs. 3.6 (−0.1–9.3), p = 0.013). Postoperative complications were significantly associated with the magnitude of the change in syndecan-1 levels (for T2 vs. T0: odds ratio: 1.08, 95% confidence interval: 1.02–1.14, p = 0.006). TXA administration was associated with reduced syndecan-1 shedding in patients undergoing posterior lumbar fusion surgery.

Impact of Anesthetic Agents on Endothelial Glycocalyx Injury during Total Knee Arthroplasty: Desflurane- vs. Propofol-Based Anesthesia-A Prospective Randomized Controlled Trial

Background

Ischemia-reperfusion injury and inflammation after tourniquet deflation in total knee arthroplasty are known to be associated with endothelial glycocalyx (EG) injury. This study is aimed at comparing EG injury between desflurane- and propofol-based anesthesia in patients undergoing total knee arthroplasty.

Materials and Methods

Patients were allocated to the desflurane group or propofol group. The opioid remifentanil was administered intraoperatively in both groups. Blood samples were obtained from the arterial line preoperatively, immediately before and 5 min after tourniquet deflation, and at 1, 6, and 24 h, postoperatively. Serum syndecan-1, cytokines (interleukin-1β, 6, 10, and tumour necrosis factor-α), and other laboratory values were investigated.

Results

Eighty patients were included in the final analysis. The change in syndecan-1 did not significantly differ between the desflurane and propofol groups (peak median level of syndecan-1; 754.5 pg/ml vs. 780.3 pg/ml, respectively, P = 0.512). Laboratory values (serum cytokines, creatinine phosphokinase, lactate dehydrogenase, and lactate levels) were also similar between the two groups. Pulmonary oxygenation was briefly improved after tourniquet deflation in the desflurane group but was similar between the two groups begging at 1 h, postoperatively.

Conclusions

The effect of desflurane was not superior to that of propofol in protecting the EG from ischemia-reperfusion injury during total knee arthroplasty. This trial is registered with Trial Registry Number NCT02756715 (http://clinicaltrials.gov).

Effect of volatile and total intravenous anesthesia on syndecan-1 shedding after minimally invasive gastrectomy: a randomized trial

This study aimed to compare the effects of volatile anesthesia and total intravenous anesthesia (TIVA) on syndecan-1 shedding in patients with gastric cancer undergoing minimally invasive gastrectomy. Patients were randomly assigned to either the Volatile (n = 68) or the TIVA (n = 68) group. Anesthesia was maintained with sevoflurane/remifentanil or propofol/remifentanil in the Volatile and TIVA groups, respectively. Serum syndecan-1 was evaluated at pre-operation, end of operation, and postoperative day (POD) 1. Inflammatory markers including white blood cell (WBC) count, neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein (CRP), were also measured at pre-operation, end of operation, and POD 1, 2, 3, and 5. The TIVA group showed significantly lower levels of syndecan-1 at the end of the operation compared to the Volatile group; however, no difference was seen between the groups at POD 1. The WBC count and NLR were significantly lower in the TIVA group at the end of the operation than the Volatile group, but there were no differences between the groups at POD 1, 2, 3, and 5. CRP levels were similar between the groups at all time points. In conclusion, despite TIVA being superior to volatile anesthesia in protecting endothelial glycocalyx during the operation, both did not prevent postoperative syndecan-1 shedding after gastrectomy.

Clinical trial registration number: NCT04183296 (ClinicalTrial.gov, 03/12/2019).

The Effects of Volatile Anesthetics on Lung Ischemia-Reperfusion Injury: Basic to Clinical Studies

Case reports from as early as the 1970s have shown that intravenous injection of even a small dose of volatile anesthetics result in fatal lung injury. Direct contact between volatile anesthetics and pulmonary vasculature triggers chemical damage in the vessel walls. A wide variety of factors are involved in lung ischemia-reperfusion injury (LIRI), such as pulmonary endothelial cells, alveolar epithelial cells, alveolar macrophages, neutrophils, mast cells, platelets, proinflammatory cytokines, and surfactant. With a constellation of factors involved, the assessment of the protective effect of volatile anesthetics in LIRI is difficult. Multiple animal studies have reported that with regards to LIRI, sevoflurane demonstrates an anti-inflammatory effect in immunocompetent cells and an anti-apoptotic effect on lung tissue. Scattered studies have dismissed a protective effect of desflurane against LIRI. While a single-center randomized controlled trial (RCT) found that volatile anesthetics including desflurane demonstrated a lung-protective effect in thoracic surgery, a multicenter RCT did not demonstrate a lung-protective effect of desflurane. LIRI is common in lung transplantation. One study, although limited due to its small sample size, found that the use of volatile anesthetics in organ procurement surgery involving "death by neurologic criteria" donors did not improve lung graft survival. Future studies on the protective effect of volatile anesthetics against LIRI must examine not only the mechanism of the protective effect but also differences in the effects of different types of volatile anesthetics, their optimal dosage, and the appropriateness of their use in the event of marked alveolar capillary barrier damage.

Novel Strategies for Endothelial Preservation in Lung Transplant Ischemia-Reperfusion Injury

Lung ischemia reperfusion (IR) injury inevitably occurs during lung transplantation. The pulmonary endothelium is the primary target of IR injury that potentially results in severe pulmonary dysfunction. Over the last decades, various molecules, receptors, and signaling pathways were identified in order to develop treatment strategies for the preservation of the pulmonary endothelium against IR injury. We here review the latest and most promising therapeutic strategies for the protection of the endothelium against IR injury. These include the stabilization of the endothelial glycocalyx, inhibition of endothelial autophagy, inhibition of adhesion molecules, targeting of angiotensin-converting enzyme, and traditional viral and novel non-viral gene transfer approaches. Though some of these strategies proved to be promising in experimental studies, very few of these treatment concepts made the transfer into clinical application. This dilemma underscores the need for more experimental evidence for the translation into clinical studies to invent therapeutic concepts against IR injury-mediated endothelial damage.

Effect of peri-operative crystalloid fluid rate on circulating hyaluronan in healthy dogs: A pilot study

Hypervolemia can damage the endothelial glycocalyx, a key regulator of vascular permeability, coagulation and inflammation. A starting peri-operative crystalloid fluid rate of 5mL/kg/h is recommended for healthy dogs undergoing elective procedures but higher rates continue to be commonly used. This study aimed to determine if a higher starting perioperative fluid rate was associated with a greater increase in plasma concentrations of hyaluronan, a marker correlated with glycocalyx damage, in systemically healthy dogs undergoing elective surgical procedures. Based on a sample size calculation, 38 dogs undergoing ovariohysterectomy or castration were randomly assigned to receive lactated Ringer's at a starting perioperative fluid rate of 10mL/kg/h (n=19) or 5mL/kg/h (n=19). Plasma hyaluronan concentrations were measured by ELISA in pre- and post-fluid therapy samples. There were no significant differences between groups in hyaluronan values before (baseline, P=0.52) or after perioperative fluid administration (P=0.62). Compared to respective baseline values, hyaluronan values significantly increased following 5 and 10ml/kg/h fluid administration (P=0.02 for both comparisons). This preliminary study identified an increase in hyaluronan over the course of fluid therapy with both the low and high fluid rate. One possible explanation is that both fluid rates contribute to glycocalyx disruption, but it should be emphasized that hyaluronan is not specific to the glycocalyx. Further studies are needed to determine the origin of the increased circulating hyaluronan and its clinical significance in dogs undergoing elective surgical procedures.

Endothelial cells, neutrophils and platelets: getting to the bottom of an inflammatory triangle

Severe fibrotic and thrombotic events permeate the healthcare system, causing suffering for millions of patients with inflammatory disorders. As late-state consequences of chronic inflammation, fibrosis and thrombosis are the culmination of pathological interactions of activated endothelium, neutrophils and platelets after vessel injury. Coupling of these three cell types ensures a pro-coagulant, cytokine-rich environment that promotes the capture, activation and proliferation of circulating immune cells and recruitment of key pro-fibrotic cell types such as myofibroblasts. As the first responders to sterile inflammatory injury, it is important to understand how endothelial cells, neutrophils and platelets help create this environment. There has been a growing interest in this intersection over the past decade that has helped shape the development of therapeutics to target these processes. Here, we review recent insights into how neutrophils, platelets and endothelial cells guide the development of pathological vessel repair that can also result in underlying tissue fibrosis. We further discuss recent efforts that have been made to translate this knowledge into therapeutics and provide perspective as to how a compound or combination therapeutics may be most efficacious when tackling fibrosis and thrombosis that is brought upon by chronic inflammation.

Effect of sevoflurane and propofol on tourniquet-induced endothelial damage: a pilot randomized controlled trial for knee-ligament surgery

BACKGROUND

The glycocalyx layer is a key structure in the endothelium. Tourniquet-induced ischemic periods are used during orthopedic surgery, and the reactive oxygen species generated after ischemia-reperfusion may mediate the shedding of the glycocalyx. Here, we describe the effects of tourniquet-induced ischemia-reperfusion and compare the effects of sevoflurane and propofol on the release of endothelial biomarkers after ischemia-reperfusion in knee-ligament surgery.

METHODS

This pilot, single-center, blinded, randomized, controlled trial included 16 healthy patients. After spinal anesthesia, hypnosis was achieved with sevoflurane or propofol according to randomization. During the perioperative period, five venous blood samples were collected for quantification of syndecan-1, heparan sulfate, and thrombomodulin from blood serum by using ELISA assays kits. Sample size calculation was performed to detect a 25% change in the mean concentration of syndecan-1 with an alpha of 0.05 and power of 80%.

RESULTS

For our primary outcome, a two-way ANOVA with post-hoc Bonferroni correction analysis showed no differences in syndecan-1 concentrations between the sevoflurane and propofol groups at any time point. In the sevoflurane group, we noted an increase in syndecan-1 concentrations 90 min after tourniquet release in the sevoflurane group from 34.6 ± 24.4 ng/mL to 47.9 ± 29.8 ng/mL (Wilcoxon test, p < 0.01) that was not observed in patients randomized to the propofol group. The two-way ANOVA showed no intergroup differences in heparan sulfate and thrombomodulin levels.

CONCLUSIONS

Superficial endothelial damage without alterations in the cell layer integrity was observed after tourniquet knee-ligament surgery. There was no elevation in serum endothelial biomarkers in the propofol group patients. Sevoflurane did not show the protective effect observed in in vitro and in vivo studies.

TRIAL REGISTRATION

The trial was registered in www.clinicaltrials.gov (ref: NCT03772054, Registered 11 December 2018).

Hypervolemia does not cause degradation of the endothelial glycocalyx layer during open hysterectomy performed under sevoflurane or propofol anesthesia

BACKGROUND

Fluid-induced hypervolemia may stimulate the release of natriuretic peptides and cause degradation (shedding) of the endothelial glycocalyx layer. Sevoflurane is believed to protect the glycocalyx, but the importance of using sevoflurane to prevent shedding during routine surgery is unclear.

METHODS

The plasma concentrations of brain natriuretic peptide and two biomarkers of glycocalyx shedding, syndecan-1, and heparan sulfate, were measured in 26 patients randomized to receive general anesthesia with sevoflurane or propofol during open abdominal hysterectomy. The fluid therapy consisted of 25 mL/kg (approximately 2 L) of Ringer´s lactate over 30 minutes. Blood hemoglobin and plasma albumin were used to indicate plasma volume expansion and capillary leakage.

RESULTS

The plasma concentrations of brain natriuretic peptide and shedding products showed low levels throughout the surgery (median brain natriuretic peptide, 21 ng/L; syndecan-1, 12.9 ng/mL; and heparan sulfate, 6.5 µg/mL), but the heparan sulfate concentration increased 2 hours post-operatively (to 17.3 µg/mL, P < .005). No differences were noted between the propofol and sevoflurane groups in any of the measured parameters. Albumin was apparently recruited to the bloodstream during the first 20 minutes, when the intravascular retention of infused fluid was almost 100%. The urine flow was <1 mL/min, despite the vigorous volume loading.

CONCLUSIONS

No relevant elevations of brain natriuretic peptide or degradation products of the glycocalyx layer were observed when hypervolemia was induced during open abdominal hysterectomy performed with sevoflurane or propofol anesthesia. Plasma volume expansion from Ringer´s lactate was pronounced.

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.

Thoracotomy for emergency repair of iatrogenic tracheal rupture: single center analysis of perioperative management and outcomes

Background

Iatrogenic tracheal ruptures are rare but life-threatening airway complications that often require surgical repair. Data on perioperative vital functions and anesthetic regimes are scarce. The goal of this study was to explore comorbidity, perioperative management, complications and outcomes of patients undergoing thoracotomy for surgical repair.

Methods

We retrospectively evaluated adult patients who required right thoracotomy for emergency surgical repair of iatrogenic posterior tracheal ruptures and were admitted to a university hospital over a 15-year period (2004–2018). The analyses included demographic, diagnostic, management and outcome data on preinjury morbidity and perioperative complications.

Results

Thirty-five patients who met the inclusion criteria were analyzed. All but two patients (96%) presented with critical underlying diseases and/or emergency tracheal intubations. The median time (interquartile range) from diagnosis to surgery was 0.3 (0.2–1.0) days. The durations of anesthesia, surgery and one-lung ventilation (OLV) were 172 (128–261) min, 100 (68–162) min, and 52 (40–99) min, respectively. The primary airway management approach to OLV was successful in only 12 patients (34%). Major complications during surgery were observed in 10 patients (29%). Four patients (11%) required cardiopulmonary resuscitation, one of whom received extracorporeal membrane oxygenation, and another one of these patients died during surgery. Major complications were associated with significantly higher all-cause 30-day mortality (p = 0.002) and adjusted mortality (p = 0.001) compared to patients with minor or no complications.

Conclusions

Surgical repair of iatrogenic tracheal ruptures requires advanced perioperative care in a specialized center due to high morbidity and potential complications. Airway management should include early anticipation of alternative OLV approaches to provide acceptable conditions for surgery.

Endothelial Glycocalyx Shedding Occurs during Ex Vivo Lung Perfusion: A Pilot Study

Background

Damage to the endothelium has been established as a key pathological process in lung transplantation and ex vivo lung perfusion (EVLP), a new technology that provides a platform for the assessment of injured donor lungs. Damage to the lung endothelial glycocalyx, a structure that lines the endothelium and is integral to vascular barrier function, has been associated with lung dysfunction. We hypothesised that endothelial glycocalyx shedding occurs during EVLP and aimed to establish a porcine model to investigate the mechanism underlying glycocalyx breakdown during EVLP.

Methods

Concentrations of endothelial glycocalyx breakdown products, syndecan-1, hyaluronan, heparan sulphate, and CD44, were measured using the ELISA and matrix metalloproteinase (MMP) activity by zymography in the perfusate of both human (n = 9) and porcine (n = 4) lungs undergoing EVLP. Porcine lungs underwent prolonged EVLP (up to 12 hours) with perfusion and ventilation parameters recorded hourly.

Results

During human EVLP, endothelial glycocalyx breakdown products in the perfusate increased over time. Increasing MMP-2 activity over time was positively correlated with levels of syndecan-1 (r = 0.886; p=0.03) and hyaluronan (r = 0.943; p=0.02). In the porcine EVLP model, hyaluronan was the only glycocalyx product detectable during EVLP (1 hr: 19 (13–84) vs 12 hr: 143 (109–264) ng/ml; p=0.13). Porcine hyaluronan was associated with MMP-9 activity (r = 0.83; p=0.02) and also with dynamic compliance (r = 0.57; p=0.03).

Conclusion

Endothelial glycocalyx products accumulate during both porcine and human EVLP, and this accumulation parallels an accumulation of matrix-degrading enzyme activity. Preliminary evidence in our porcine EVLP model suggests that shedding may be related to organ function, thus warranting additional study.