Influence of propofol and volatile anaesthetics on the inflammatory response in the ventilated lung

Effects of anesthesia with sevoflurane on outcome parameters in murine experimental studies

PURPOSE

Multiple murine studies modelling the immuno-pathophysiological consequences of trauma, shock, burn or sepsis were performed during the last decades. Almost every animal model requires anesthesia for practical and ethical reasons. Furthermore, often, corresponding control groups involve untreated animals without or with a limited exposure to anesthetics. However, the influences of anesthetic drugs on immuno-pathophysiological reactions remain insufficiently investigated. Therefore, we aimed to closer characterize the anesthetic impact exemplified by sevoflurane on the organ performance in mice and thereby investigate the influence of anesthesia itself on major outcome parameters in animal studies.

METHODS

C57/BL6 mice were subjected either to 270 min of sevoflurane narcosis or directly euthanized. Plasma, BAL-fluids, lungs, kidneys, liver and intestine were collected and examined for immunological, functional and morphological changes.

RESULTS

Systemic levels of the cytokine keratinocyte chemoattractant (KC) were raised in the narcosis group, while concentrations of high mobility group box protein 1 (HMGB-1) as a major inflammatory marker were reduced. In the lungs, levels of HMGB-1 and interleukin 6 (IL-6) were reduced. In contrast, systemic concentrations of intestinal fatty acid binding-protein (i-FABP) as an intestinal damage marker were elevated. Furthermore, liver-type fatty acid binding-protein (L-FABP) levels were lower in the narcosis animals, and inflammatory markers were reduced in liver tissues. Anesthesia also ameliorated the inflammatory reaction in renal tissues, while plasma levels of urea and creatinine were elevated, reflecting either dehydration and/or impaired renal function.

CONCLUSION

As anesthesia with sevoflurane exhibited distinct effects in different organs, it is difficult to predict its specific impact on targets of interest in in vivo studies. Therefore, further studies are required to clarify the effects of different anesthetic drugs. Overall, the inclusion of a control group subjected to the same anesthesia protocol as the experimental groups of interest seems helpful to precisely define the inherent impact of the anesthetic when investigating immuno-pathophysiologic conditions in vivo.

Total Intravenous Anesthesia Is Preferred Over Volatile Agents in Cardiac Surgery

The choice of maintenance anesthetic during cardiopulmonary bypass has been a subject of ongoing debate. Systematic reviews on the topic have so far failed to demonstrate a difference between volatile agents and total intravenous anesthesia (TIVA) in terms of mortality, myocardial injury, and neurological outcomes. Studies using animal models and noncardiac surgical populations suggest numerous mechanisms whereby TIVA has been associated with more favorable outcomes. However, even if the different anesthetic methods are assumed to equivalent in terms of patient outcomes in the context of cardiac surgery, additional factors, namely variables of occupational exposure and environmental impact, strongly support the preferred use of TIVA.

The impact of stress and anesthesia on animal models of infectious disease

Stress and general anesthesia have an impact on the functional response of the organism due to the detrimental effects on cardiovascular, immunological, and metabolic function, which could limit the organism's response to an infectious event. Animal studies have formed an essential step in understanding and mitigating infectious diseases, as the complexities of physiology and immunity cannot yet be replicated in vivo. Using animals in research continues to come under increasing societal scrutiny, and it is therefore crucial that the welfare of animals used in disease research is optimized to meet both societal expectations and improve scientific outcomes. Everyday management and procedures in animal studies are known to cause stress, which can not only cause poorer welfare outcomes, but also introduces variables in disease studies. Whilst general anesthesia is necessary at times to reduce stress and enhance animal welfare in disease research, evidence of physiological and immunological disruption caused by general anesthesia is increasing. To better understand and quantify the effects of stress and anesthesia on disease study and welfare outcomes, utilizing the most appropriate animal monitoring strategies is imperative. This article aims to analyze recent scientific evidence about the impact of stress and anesthesia as uncontrolled variables, as well as reviewing monitoring strategies and technologies in animal models during infectious diseases.

The deleterious impact of exposure to different inhaled anesthetics is time dependent

In this study, the effects of exposure to isoflurane, sevoflurane and desflurane on the oxidative response and inflammation at different times was analyzed in the lungs of adult C57BL/6 mice. 120 animals were divided into 3 groups (n = 40): Isoflurane (ISO), Sevoflurane (SEV) and Desflurane (DES) and exposed to these anesthetics for 1 h (n = 10), 2 h (n = 10) and 3 h (n = 10), at a minimum alveolar concentration (MAC) equal to 1. The control group (CG) (n = 10) was exposed to ambient air. 24 h after the experimental protocol, the animals were euthanized and the bronchoalveolar lavage fluid (BALF), blood and lung tissue samples were collected. In the BALF, animals exposed to isoflurane for 2 h and 3 h showed a greater influx of leukocytes, especially macrophages compared to the CG. The ISO3h had lower leukocyte counts in the peripheral blood compared to CG, ISO1h and ISO2h. There was an increase in CCL-2 levels in the ISO3h compared to the CG. Superoxide dismutase activity was higher in ISO1h compared to CG. The activity of catalase was higher in the ISO1h and ISO2h compared to the CG. The lipid peroxidation, as well as carbonylated protein were higher in the ISO3h compared to the CG (p < 0.05). Similar results were observed in the exposure of SEV and DES compared to inflammation and redox imbalance in different periods. This study demonstrated that time is a determinant to promote a local and systemic inflammatory response to different inhalational anesthetics in a healthy murine model.

Etomidate Alleviates Ischemia-Anoxia Reperfusion Injury in Intestinal Epithelial Cells by Inhibiting the Activation of traf6-Regulated NF-KB Signaling

Objective: The present study aimed to investigate the role of etomidate in intestinal cell ischemia and hypoxia-reperfusion injury and potential mechanisms. Method: In this study, we establish the intestinal epithelial cells ischemia-reperfusion model in vitro. CCK8 was used to detect cell viability and flow cytometry assay was used to detect apoptosis levels of treated OGD/R model cells. ELISA measured the expression level of oxidative stress factors and inflammatory factors. Furthermore, western blot assay was used to detect the expression the apoptosis-related factors and TNFR-associated factors in treated OGD/R model cells. Result: Etomidate does not affect the activity of intestinal epithelial cells, and can protect intestinal epithelial cells to reduce ischemiareperfusion injury, and the expression of inflammatory factors and oxidative stress in cells with mild intestinal epithelial ischemia-reperfusion injury. Etomidate alleviates apoptosis of intestinal epithelial ischemia-reperfusion injury cells. Etomidate inhibits the activation of traf6-mediated NF-κB signal during ischemia-anoxia reperfusion of intestinal epithelial cells. Conclusion: Taken together, our study demonstrated that etomidate attenuates inflammatory response and apoptosis in intestinal epithelial cells during ischemic hypoxia-reperfusion injury and inhibits activation of NF-κB signaling regulated by TRAF6.

The Effects of Anesthetics and Perioperative Medications on Immune Function: A Narrative Review

Preclinical and clinical studies have sought to better understand the effect of anesthetic agents, both volatile and intravenous, and perioperative adjuvant medications on immune function. The immune system has evolved to incorporate both innate and adaptive components, which are delicately interwoven and essential for host defense from pathogens and malignancy. This review summarizes the complex and nuanced relationship that exists between each anesthetic agent or perioperative adjuvant medication studied and innate and adaptive immune function with resultant clinical implications. The most commonly used anesthetic agents were chosen for review including volatile agents (sevoflurane, isoflurane, desflurane, and halothane), intravenous agents (propofol, ketamine, etomidate, and dexmedetomidine), and perioperative adjuvant medications (benzodiazepines, opioids, nonsteroidal anti-inflammatory drugs [NSAIDs], and local anesthetic agents). Patients who undergo surgery experience varying combinations of the aforementioned anesthetic agents and adjuncts, depending on the type of surgery and their comorbidities. Each has unique effects on immunity, which may be more or less ideal depending on the clinical situation. Further study is needed to better understand the clinical effects of these relationships so that patient-specific strategies can be developed to improve surgical outcomes.

Anesthetics may modulate cancer surgical outcome: a possible role of miRNAs regulation

Background

microRNAs (miRNAs) are single-stranded and noncoding RNA molecules that control post-transcriptional gene regulation. miRNAs can be tumor suppressors or oncogenes through various mechanism including cancer cell biology, cell-to-cell communication, and anti-cancer immunity.

Main Body

Anesthetics can affect cell biology through miRNA-mediated regulation of messenger RNA (mRNA). Indeed, sevoflurane was reported to upregulate miR-203 and suppresses breast cancer cell proliferation. Propofol reduces matrix metalloproteinase expression through its impact on miRNAs, leading to anti-cancer microenvironmental changes. Propofol also modifies miRNA expression profile in circulating extracellular vesicles with their subsequent anti-cancer effects via modulating cell-to-cell communication.

Conclusion

Inhalational and intravenous anesthetics can alter cancer cell biology through various cellular signaling pathways induced by miRNAs’ modification. However, this area of research is insufficient and further study is needed to figure out optimal anesthesia regimens for cancer patients.

Sedating Mechanically Ventilated COVID-19 Patients with Volatile Anesthetics: Insights on the Last-Minute Potential Weapons

Coronavirus Disease 2019 (COVID-19) has spread globally with the number of cases exceeding seventy million. Although trials on potential treatments of COVID-19 Acute Respiratory Distress Syndrome (ARDS) are promising, the introduction of an effective therapeutic intervention seems elusive. In this review, we explored the potential therapeutic role of volatile anesthetics during mechanical ventilation in the late stages of the disease. COVID-19 is thought to hit the human body via five major mechanisms: direct viral damage, immune overactivation, capillary thrombosis, loss of alveolar capillary membrane integrity, and decreased tissue oxygenation. The overproduction of pro-inflammatory cytokines will eventually lead to the accumulation of inflammatory cells in the lungs, which will lead to ARDS requiring mechanical ventilation. Respiratory failure resulting from ARDS is thought to be the most common cause of death in COVID-19. The literature suggests that these effects could be directly countered by using volatile anesthetics for sedation. These agents possess multiple properties that affect viral replication, immunity, and coagulation. They also have proven benefits at the molecular, cellular, and tissue levels. Based on the comprehensive understanding of the literature, short-term sedation with volatile anesthetics may be beneficial in severe stages of COVID-19 ARDS and trials to study their effects should be encouraged.

Propofol reduces renal ischemia/reperfusion-induced acute lung injury by stimulating sirtuin 1 and inhibiting pyroptosis

The activation of pyroptosis is an important feature of renal ischemia/reperfusion (rI/R)-induced acute lung injury (ALI). Propofol, a general anesthetic, is known to inhibit inflammation in I/R-induced ALI. We investigated whether propofol could suppress pyroptosis during rI/R-induced ALI by upregulating sirtuin 1 (SIRT1). We generated an in vivo model of rI/R-induced ALI by applying microvascular clamps to the renal pedicles of rats for 45 min. Pathological studies revealed that rI/R provoked substantial lung injury and inflammatory cell infiltration. The rI/R stimulus markedly activated pyroptotic proteins such as NLRP3, ASC, caspase 1, interleukin-1β and interleukin-18 in the lungs, but reduced the mRNA and protein levels of SIRT1. Propofol treatment greatly inhibited rI/R-induced lung injury and pyroptosis, whereas it elevated SIRT1 expression. Treatment with the selective SIRT1 inhibitor nicotinamide reversed the protective effects of propofol during rI/R-induced ALI. Analogous defensive properties of propofol were detected in vitro in rat alveolar macrophages incubated with serum from the rI/R rat model. These findings indicate that propofol attenuates rI/R-induced ALI by suppressing pyroptosis, possibly by upregulating SIRT1 in the lungs.

Comparison of the Effects of Low-flow and Normal-flow Desflurane Anaesthesia on Inflammatory Parameters in Patients Undergoing Laparoscopic Cholecystectomy

Objective

According to previous studies, anaesthesia type has an important effect on immune response. However, there are limited data determining the effect of low-flow and normal-flow desflurane anaesthesia on inflammatory parameters. This study aimed to investigate the effect of low-flow and normal-flow desflurane anaesthesia on inflammatory parameters in patients undergoing laparoscopic cholecystectomy.

Methods

A total of 92 patients who underwent laparoscopic cholecystectomy were retrospectively included in this study. The patients were divided into the following 2 groups according to the type of anaesthesia they received: low-flow desflurane anaesthesia group (fresh gas flow rate: 0.5 L min^-1) and normal-flow desflurane anaesthesia group (fresh gas flow rate: 2 L min^-1). Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were obtained before the procedure and 6 hours after the end of the procedure for all patients.

Results

Although pre-procedural NLR and PLR were similar between the normal-flow and low-flow anaesthesia groups, post-procedural NLR (4.38±2.00 vs. 3.51±1.37, p=0.023) and PLR (144.38±71.04 vs. 120.58±35.35, p=0.037) were significantly higher in the normal-flow anaesthesia group. In addition, compared with pre-procedural values, post-procedural NLR (from 2.31±1.02 to 4.38±2.00, p<0.001) and PLR (from 125.60±50.97 to 144.38±71.04, p=0.017) were significantly increased in the normal-flow anaesthesia group, whereas post-procedural NLR (from 2.88±2.51 to 3.51±1.37, p=0.135) and PLR (from 121.86±42.78 to 120.58±35.35, p=0.847) did not change significantly in the low-flow anaesthesia group.

Conclusion

The study results indicated that postoperative inflammatory response was significantly lower with low-flow desflurane anaesthesia than with normal-flow desflurane anaesthesia.

The effect of anesthetic preconditioning with sevoflurane on intracellular signal-transduction pathways and apoptosis, in a lung autotransplant experimental model

Background

Anesthetic pre-conditioning attenuates inflammatory response during ischemia-reperfusion lung injury. The molecular mechanisms to explain it are not fully understood. The aim of our investigation was to analyze the molecular mechanism that explain the anti-inflammatory effects of anesthetic pre-conditioning with sevoflurane focusing on its effects on MAPKs (mitogen-activated protein kinases), NF-κB (nuclear factor kappa beta) pathways, and apoptosis in an experimental lung autotransplant model.

Methods

Twenty large white pigs undergoing pneumonectomy plus lung autotransplant were divided into two 10-member groups on the basis of the anesthetic received (propofol or sevoflurane). Anesthetic pre-conditioning group received sevoflurane 3% after anesthesia induction and it stopped when one-lung ventilation get started. Control group did not receive sevoflurane in any moment during the whole study period. Intracellular signal-transduction pathways (MAPK family), transcription factor (NF-κB), and apoptosis (caspases 3 and 9) were analyzed during experiment.

Results

Pigs that received anesthetic pre-conditioning with sevoflurane have shown significant lower values of MAPK-p38, MAPK-P-p38, JNK (c-Jun N-terminal kinases), NF-κB p50 intranuclear, and caspases (p < 0.05) than pigs anesthetized with intravenous propofol.

Conclusions

Lung protection of anesthetic pre-conditioning with sevoflurane during experimental lung autotransplant is, at least, partially associated with MAPKs and NF κB pathways attenuation, and antiapoptotic effects.

[The effect of anesthetic preconditioning with sevoflurane on intracellular signal-transduction pathways and apoptosis, in a lung autotransplant experimental model]

BACKGROUND

Anesthetic pre-conditioning attenuates inflammatory response during ischemia-reperfusion lung injury. The molecular mechanisms to explain it are not fully understood. The aim of our investigation was to analyze the molecular mechanism that explain the anti-inflammatory effects of anesthetic pre-conditioning with sevoflurane focusing on its effects on MAPKs (mitogen-activated protein kinases), NF-κB (nuclear factor kappa beta) pathways, and apoptosis in an experimental lung autotransplant model.

METHODS

Twenty large white pigs undergoing pneumonectomy plus lung autotransplant were divided into two 10-member groups on the basis of the anesthetic received (propofol or sevoflurane). Anesthetic pre-conditioning group received sevoflurane 3% after anesthesia induction and it stopped when one-lung ventilation get started. Control group did not receive sevoflurane in any moment during the whole study period. Intracellular signal-transduction pathways (MAPK family), transcription factor (NF-κB), and apoptosis (caspases 3 and 9) were analyzed during experiment.

RESULTS

Pigs that received anesthetic pre-conditioning with sevoflurane have shown significant lower values of MAPK-p38, MAPK-P-p38, JNK (c-Jun N-terminal kinases), NF-κB p50 intranuclear, and caspases (p<0.05) than pigs anesthetized with intravenous propofol.

CONCLUSIONS

Lung protection of anesthetic pre-conditioning with sevoflurane during experimental lung autotransplant is, at least, partially associated with MAPKs and NF κB pathways attenuation, and antiapoptotic effects.

Immune Modulation by Volatile Anesthetics

Volatile general anesthetics continue to be an important part of clinical anesthesia worldwide. The impact of volatile anesthetics on the immune system has been investigated at both mechanistic and clinical levels, but previous studies have returned conflicting findings due to varied protocols, experimental environments, and subject species. While many of these studies have focused on the immunosuppressive effects of volatile anesthetics, compelling evidence also exists for immunoactivation. Depending on the clinical conditions, immunosuppression and activation due to volatile anesthetics can be either detrimental or beneficial. This review provides a balanced perspective on the anesthetic modulation of innate and adaptive immune responses as well as indirect effectors of immunity. Potential mechanisms of immunomodulation by volatile anesthetics are also discussed. A clearer understanding of these issues will pave the way for clinical guidelines that better account for the impact of volatile anesthetics on the immune system, with the ultimate goal of improving perioperative management.

Desflurane inhalation before ischemia increases ischemia-reperfusion-induced vascular leakage in isolated rabbit lungs

BACKGROUND

Isoflurane and sevoflurane protect lungs with ischemia-reperfusion (IR) injury. We examined the influence of desflurane on IR lung injury using isolated rabbit lungs perfused with a physiological salt solution.

METHODS

The isolated lungs were divided into three groups: IR, desflurane-treated ischemia-reperfusion (DES-IR), and ventilation/perfusion-continued control (Cont) groups (n = 6 per group). In the DES-IR group, inhalation of desflurane at 1 minimum alveolar concentration (MAC) was conducted in a stable 30-min phase. In the IR and DES-IR groups, ventilation/perfusion was stopped for 75 min after the stable phase. Subsequently, they were resumed. Each lung was placed on a balance, and weighed. Weight changes were measured serially throughout this experiment. The coefficient of filtration (K_fc) was determined immediately before ischemia and 60 min after reperfusion. Furthermore, bronchoalveolar lavage fluid (BALF) was collected from the right bronchus at the completion of the experiment. After the completion of the experiment, the left lung was dried, and the lung wet-to-dry weight ratio (W/D) was calculated.

RESULTS

The K_fc values at 60 min after perfusion were 0.40 ± 0.13 ml/min/mmHg/100 g in the DES-IR group, 0.26 ± 0.07 ml/min/mmHg/100 g in the IR group, and 0.22 ± 0.08 (mean ± SD) ml/mmHg/100 g in the Cont group. In the DES-IR group, the K_fc at 60 min after the start of reperfusion was significantly higher than in the other groups. In the DES-IR group, W/D was significantly higher than in the Cont group. In the DES-IR group, the BALF concentrations of nitric oxide metabolites were significantly higher than in the other groups. In the DES-IR group, the total amount of vascular endothelial growth factor in BALF was significantly higher than in the Cont group.

CONCLUSIONS

The pre-inhalation of desflurane at 1 MAC exacerbates pulmonary IR injury in isolated/perfused rabbit lungs.

Anti-inflammatory effects of propofol on lipopolysaccharides-treated rat hepatic Kupffer cells

This study is set to explore the role of commonly used intravenous anesthetic propofol on the inflammatory response of rat liver Kupffer cells (KCs) induced by lipopolysaccharides (LPS). The isolated KCs were cultured at the density of 1 × 10(5)/ml, divided into five groups randomly after 48 h culture: group C, control group; group L, KCs were treated with 1 μg/ml LPS for 24 h; groups P1, P2, P3, KCs were pretreated with propofol at low (25 μM), medium (50 μM), high (100 μM) concentration for 2 h, respectively, and then were stimulated with 1 μg/ml LPS for 24 h. The expressions of tumor necrosis factor-α (TNF-α) mRNA and interleukin-1β (IL-1β) mRNA of every group were measured by RT-PCR. Nuclear NF-ΚB p65 was determined by Western blot. The concentrations of IL-1β and TNF-α in supernatant were measured by ELISA. Compared with the group C, TNF-α mRNA and IL-1β mRNA in group L were significantly up-regulated and NF-ΚB p65 was significantly up-regulated after LPS treatment (P < 0.05). Meanwhile, TNF-α and IL-1β were also significantly increased (P < 0.05). With propofol the mRNA expressions of aforementioned inflammatory mediators were significantly down-regulated and NF-ΚB p65 was significantly inhibited in group P2 and P3 (P < 0.05), compared with group L. However, low propofol concentration did not exhibit any effect (group P1, P > 0.05). Propofol at medium and high concentration can counteract the LPS-induced inflammatory response in KCs by regulating NF-ΚB p65 protein expression.

Sevoflurane prevents liver inflammatory response induced by lung ischemia-reperfusion

BACKGROUND

Transplants cause ischemia-reperfusion (IR) injury that can affect distant organs. Liver is particularly sensitive to IR injury. The present randomized experimental study was designed to investigate a possible protective effect of sevoflurane against liver inflammatory response to lung IR in a lung upper lobe left autotransplant model.

METHODS

Two groups (sevoflurane and control) of eight swines each were submitted to upper lobe left lung autotransplant. Hypnotic maintenance was performed with sevoflurane 3% or propofol 8 to 10 mg/kg per hr until pneumonectomy was done; then propofol was used for all animals. Blood and liver samples were taken in four different moments: prepneumonectomy, prereperfusion, 10 min postreperfusion and 30 min postreperfusion to measure levels of interleukin (IL)-1β, IL-10, tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1, nuclear factor (NF)-κB, C-reactive protein, ferritin and caspase 3. Non-parametric test was used to find statistical meaning.

RESULTS

Lung IR markedly increased the expression of TNF-α, IL-1β, MCP-1, NF-κB and caspase activity in control livers compared with basal levels, whereas liver IL-10 expression decreased 10 and 30 min post-reperfusion. Sevoflurane significantly decreased TNF-α, IL-1β, MCP-1, NF-κB liver expression and caspase 3 activity. Sevoflurane also reverted the lung IR-induced decrease in IL-10 expression.

CONCLUSIONS

The present results indicate that lung IR caused hepatic injury. Sevoflurane attenuated liver injury in a model of upper lobe left lung autotransplant in pigs.

The immune response to anesthesia: part 2 sedatives, opioids, and injectable anesthetic agents

OBJECTIVE

To review the immune response to injectable anesthetics and sedatives and to compare the immunomodulatory properties between inhalation and injectable anesthetic protocols.

STUDY DESIGN

Review.

METHODS AND DATABASES

Multiple literature searches were performed using PubMed and Google Scholar from March 2012 through November 2013. Relevant anesthetic and immune terms were used to search databases without year published or species constraints. The online database for Veterinary Anaesthesia and Analgesia and the Journal of Veterinary Emergency and Critical Care were searched by issue starting in 2000 for relevant articles.

CONCLUSION

Sedatives, injectable anesthetics, opioids, and local anesthetics have immunomodulatory effects that may have positive or negative consequences on disease processes such as endotoxemia, generalized sepsis, tumor growth and metastasis, and ischemia-reperfusion injury. Therefore, anesthetists should consider the immunomodulatory effects of anesthetic drugs when designing anesthetic protocols for their patients.

Effects of anesthesia with sevoflurane and propofol on the cytokine/chemokine production at the airway epithelium during esophagectomy

Post-operative pulmonary complications such as pneumonia, acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are closely associated with morbidity and mortality after esophagectomy. One lung ventilation (OLV) is commonly used during esophagectomy. However, the effect of the anesthetic agents on the inflammatory response induced by OLV has yet to be evaluated, particularly during esophagectomy, which causes several complications in the lung. The aim of the present study was to determine the effects of anesthetic agents, such as sevoflurane or propofol, on the inflammatory reactions at the airway. Twenty patients undergoing esophagectomy were randomized to receive either sevoflurane (n=10) or propofol (n=10) as a main anesthetic agent. Epithelial lining fluid (ELF) was obtained from ventilated‑dependent lung (DL) and collapsed non-dependent lung (NDL) by a bronchoscopic microsampling method. The levels of inflammatory cytokines and chemokine [tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, IL-10 and IL-12p70] in the ELF were measured using multiplexed bead-based immunoassays before and after OLV. The results indicated that the levels of IL-6 in ELF were significantly increased in both the ventilated DL and collapsed NDL after OLV compared with the levels prior to OLV in the sevoflurane group. By contrast, there was no significant change in the IL-6 levels in the propofol group in the ventilated DL and collapsed NDL before and after OLV. Similarly, IL-8 levels were markedly increased in the ventilated DL and collapsed NDL after OLV compared with those before OLV in the sevoflurane group, whereas there was no significant change in IL-8 levels in the propofol group in the ventilated DL and collapsed NDL before and after OLV. In contrast to the changes in IL-6 and IL-8 levels, levels of IL-10, an anti-inflammatory cytokine, were not obviously changed in both the ventilated DL and collapsed NDL before and after OLV in the sevoflurane group. However, IL-10 levels in the propofol group were increased in the ventilated DL and collapsed NDL after OLV compared with those before OLV. Of note, the levels of TNF-α, IL-1β and IL-12p70 in ELF were below the detection limits. These observations suggested that propofol anesthesia more potently suppresses the surgical stress-induced inflammatory perturbation at the local milieu of the airway during esophagectomy compared with sevoflurane anesthesia.

Anesthesia, surgery, illness and Alzheimer's disease

Patients and their families have, for many decades, detected subtle changes in cognition subsequent to surgery, and only recently has this been subjected to scientific scrutiny. Through a combination of retrospective human studies, small prospective biomarker studies, and experiments in animals, it is now clear that durable consequences of both anesthesia and surgery occur, and that these intersect with the normal processes of aging, and the abnormal processes of chronic neurodegeneration. It is highly likely that inflammatory cascades are at the heart of this intersection, and if confirmed, this suggests a therapeutic strategy to mitigate enhanced neuropathology in vulnerable surgical patients.

Protective mechanical ventilation during general anesthesia for open abdominal surgery improves postoperative pulmonary function

BACKGROUND

The impact of intraoperative ventilation on postoperative pulmonary complications is not defined. The authors aimed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function.

METHODS

Prospective randomized, open-label, clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure (standard ventilation strategy) or tidal volumes of 7 ml/kg ideal body weight, 10 cm H2O positive end-expiratory pressure, and recruitment maneuvers (protective ventilation strategy). Modified Clinical Pulmonary Infection Score, gas exchange, and pulmonary functional tests were measured preoperatively, as well as at days 1, 3, and 5 after surgery.

RESULTS

Patients ventilated protectively showed better pulmonary functional tests up to day 5, fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1, 3, and 5 (mmHg; mean ± SD): 77.1 ± 13.0 versus 64.9 ± 11.3 (P = 0.0006), 80.5 ± 10.1 versus 69.7 ± 9.3 (P = 0.0002), and 82.1 ± 10.7 versus 78.5 ± 21.7 (P = 0.44) respectively. The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3. The percentage of patients in hospital at day 28 after surgery was not different between groups (7 vs. 15% respectively, P = 0.42).

CONCLUSION

A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay.

Caveolar uptake and endothelial-protective effects of nanostructured lipid carriers in acid aspiration murine acute lung injury

PURPOSE

Nanostructured lipid carriers (NLC), nanosized phospholipids/triglyceride particles developed for drug delivery, are considered biologically inactive. We assessed the efficacy of unloaded NLC as experimental treatment for acute lung injury (ALI).

METHODS

To induce ALI, C57Black/6 male mice received intratracheal injections of HCl or saline; A single dose of 16 mg/Kg NLC or saline was injected intravenously concomitantly with HCl challenge. NLC uptake mechanisms and effects on endothelial permeability and signaling were studied in cultured endothelial cells and neutrophils.

RESULTS

NLC pre-treatment attenuated pulmonary microvascular protein leak, airspace inflammatory cells, thrombin proteolytic activity and histologic lung injury score 24 h post insult. Using fluorescence measurements and flow cytometry in mouse lung microvascular endothelial cell culture homogenates, we determined that NLC rendered fluorescent by curcumin labeling are taken up by endothelial cells from mice expressing caveolin-1, the coat protein of caveolar endocytic vesicles, but not from caveolin-1 gene-disrupted mice, which lack caveolae. In contrast, conventional emulsions (CE), consisting of larger particles, were not incorporated. In addition, NLC pre-treatment of cultured human lung microvascular endothelial cells abrogated thrombin-induced activation of p44/42, albumin permeability response, actin cytoskeletal remodeling and interleukin-6 production. Finally, NLC but not CE abrogated lipopolysaccharide-triggered interleukin-8 release.

CONCLUSIONS

NLC are engulfed by endothelial caveolae and possess endothelial-protective effects. These novel properties may be of potential utility in ALI.

Propofol attenuates pulmonary injury induced by collapse and reventilation of lung in rabbits

Propofol is an anesthetic drug with antioxidant and anti-inflammatory properties. We previously found that propofol attenuated lipopolysaccharide-induced acute lung injury in rabbits. This study was performed to evaluate the effects of propofol on lung injury caused by collapse and reventilation in rabbits. The wet/dry weight ratio of the lung, lung injury scores, percentage of polymorphonuclear leukocytes, albumin concentration, malondialdehyde, and interleukin-8 levels in bronchoalveolar lavage fluid were significantly increased in both lungs of the reventilation group. The degree of increase in these parameters was more significant in the right (reventilated) than in the left (non-reventilated) lung. Propofol attenuated these changes. These findings suggest that reventilation of a collapsed lung can cause injury in the contralateral non-reventilated lung as well as the reventilated lung. Propofol may provide a beneficial effect on lung injury induced by collapse and reventilation of the lung.

Sevoflurane reduces clinical disease in a mouse model of multiple sclerosis

Background

Inhalational anesthetics have been shown to influence T cell functions both in vitro and in vivo, in many cases inducing T cell death, suggesting that exposure to these drugs could modify the course of an autoimmune disease. We tested the hypothesis that in mice immunized to develop experimental autoimmune encephalomyelitis (EAE), a well established model of multiple sclerosis (MS), treatment with the commonly used inhalational anesthetic sevoflurane would attenuate disease symptoms.

Methods

C57Bl6 female mice were immunized with myelin oligodendrocyte glycoprotein (MOG) peptide residues 35 to 55 to induce a chronic demyelinating disease. At day 10 after immunization, the mice were subjected to 2 h of 2.5% sevoflurane in 100% oxygen, or 100% oxygen, alone. Following treatment, clinical scores were monitored up to 4 weeks, after which brain histology was performed to measure the effects on astrocyte activation and lymphocyte infiltration. Effects of sevoflurane on T cell activation were studied using splenic T cells isolated from MOG peptide-immunized mice, restimulated ex vivo with MOG peptide or with antibodies to CD3 and CD28, and in the presence of different concentrations of sevoflurane. T cell responses were assessed 1 day later by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for proliferation, lactate dehydrogenase (LDH) release for cell death, and inflammatory activation by production of interleukin (IL)-17 and interferon (IFN)γ.

Results

Clinical scores in the oxygen-treated group increased until day 28 at which time they showed moderate to severe disease (average clinical score of 2.9). In contrast, disease progression in the sevoflurane-treated group increased to 2.1 at day 25, after which it remained unchanged until the end of the study. Immunohistochemical analysis revealed reduced numbers of infiltrating leukocytes and CD4⁺ cells in the CNS of the sevoflurane-treated mice, as well as reduced glial cell activation. In splenic T cells, low doses of sevoflurane reduced IFNγ production, cell proliferation, and increased LDH release.

Conclusions

These results are the first to show attenuation of EAE disease by an inhaled anesthetic and are consistent with previous reports that inhaled anesthetics, including sevoflurane, can suppress T cell activation that, in the context of autoimmune diseases such as MS, could lead to reduced clinical progression.