Martin Schläpfer

Sevoflurane ameliorates gas exchange and attenuates lung damage in experimental lipopolysaccharide-induced lung injury.

Background:Acute lung injury is a common complication in critically ill patients. Several studies suggest that volatile anesthetics have immunomodulating effects. The aim of the current study was to assess possible postconditioning with sevoflurane in an in vivo model of endotoxin-induced lung injury. Methods:Rats were anesthetized, tracheotomized, and mechanically ventilated. Lipopolysaccharide (saline as control) was administered intratracheally. Upon injury after 2 h of propofol anesthesia, general anesthesia was continued with either sevoflurane or propofol for 4 h. Arterial blood gases were measured every 2 h. After 6 h of injury, bronchoalveolar lavage was performed and lungs were collected. Total cell count, albumin content, concentrations of the cytokines cytokine-induced neutrophil chemoattractant-1 and monocyte chemoattractant protein-1, and phospholipids were analyzed in bronchoalveolar lavage fluid. Expression of messenger RNA for the two cytokines and for surfactant protein B was determined in lung tissue. Histopathologic examination of the lung was performed. Results:Significant improvement of the ratio of oxygen tension to inspired oxygen fraction was shown with sevoflurane (mean ± SD: 243 ± 94 mmHg [32.4 kPa]) compared with propofol (88 ± 19 mmHg [11.7 kPa]). Total cell count representing effector cell recruitment as well as albumin content as a measure of lung permeability were significantly decreased in the sevoflurane–lipopolysaccharide group compared with the propofol–lipopolysaccharide group in bronchoalveolar lavage fluid. Expression of the cytokines protein in bronchoalveolar lavage fluid as well as messenger RNA in lung tissue was significantly lower in the sevoflurane–lipopolysaccharide group compared with the propofol–lipopolysaccharide group. Conclusions:Postconditioning with sevoflurane attenuates lung damage and preserves lung function in an in vivo model of acute lung injury.

The volatile anaesthetic sevoflurane attenuates lipopolysaccharide-induced injury in alveolar macrophages.

Acute lung injury (ALI) is a well‐defined inflammation whereby alveolar macrophages play a crucial role as effector cells. As shown previously in numerous experimental approaches, volatile anaesthetics might reduce the degree of injury in pre‐ or post‐conditioning set‐ups. Therefore, we were interested to evaluate the effect of the application of the volatile anaesthetic sevoflurane on alveolar macrophages regarding the expression of inflammatory mediators upon lipopolysaccharide (LPS) stimulation in vitro. Alveolar macrophages were stimulated with LPS. Two hours later, cells were exposed additionally to air (control) or to sevoflurane‐containing air for 4, 6, 8, 12 or 24 h. Tumour necrosis factor (TNF)‐α, cytokine‐induced neutrophil chemoattractant‐1 (CINC‐1), macrophage‐inflammatory protein‐2 (MIP‐2) and monocyte chemoattractant protein‐1 (MCP‐1) proteins were determined and chemotaxis assays were performed. To evaluate possible cellular signalling pathways phosphorylation of the kinases extracellular‐regulated kinase (ERK) and Akt was assessed. In the early phase of sevoflurane post‐conditioning expression of TNF‐α, CINC‐1, MIP‐2 and MCP‐1 was attenuated, leading to a diminished chemotaxis reaction for neutrophils. Phosphorylation of ERK seems to be a possible cellular mechanism in the sevoflurane‐induced protection in vitro. Pharmacological post‐conditioning of alveolar macrophages with sevoflurane immunmodulates the inflammatory response upon stimulation with endotoxin. This might be a possible option for a therapeutical approach in ALI.

Late pharmacologic conditioning with volatile anesthetics after cardiac surgery

IntroductionThe aim of this randomized controlled trial was to investigate whether volatile anesthetics used for postoperative sedation have any beneficial effects on myocardial injury in cardiac surgery patients after on-pump valve replacement.MethodsAnesthesia was performed with propofol. After arrival in the intensive care unit (ICU), 117 patients were randomized to be sedated for at least 4 hours with either propofol or sevoflurane. Sevoflurane was administered by using the anesthetic-conserving device. Troponin T, creatine kinase, creatine kinase from heart muscle tissue, myoglobin, and oxygenation index were determined on arrival at the ICU, 4 hours after sedation, and in the morning of the first postoperative day (POD1). Primary end points were cardiac injury markers on POD1. As secondary end points oxygenation, postoperative pulmonary complications, and ICU and hospital stay were documented.ResultsFifty-six patients were analyzed in the propofol arm, and 46 patients in the sevoflurane arm. Treatment groups were comparable with regard to patient demographics and intraoperative characteristics. Concentration of troponin T as the most sensitive marker for myocardial injury at POD1 was significantly lower in the sevoflurane group compared with the propofol group (unadjusted difference, -0.4; 95% CI, -0.7 to -0.1; P < 0.01; adjusted difference, -0.2; 95% CI, -0.4 to -0.02; P = 0.03, respectively).ConclusionsThe data presented in this investigation indicate that late postconditioning with the volatile anesthetic sevoflurane might mediate cardiac protection, even with a late, brief, and low-dose application.Trial registrationClinicalTrials.gov: NCT00924222.

Hypoxia of the growing liver accelerates regeneration

Background. After portal vein ligation of 1 side of the liver, the other side regenerates at a slow rate. This slow growth may be accelerated to rapid growth by adding a transection between the 2 sides, i.e., performing portal vein ligation and parenchymal transection. We found that in patients undergoing portal vein ligation and parenchymal transection, portal vein hyperflow in the regenerating liver causes a significant reduction of arterial flow due to the hepatic arterial buffer response. We postulated that the reduction of arterial flow induces hypoxia in the regenerating liver and used a rat model to assess hypoxia and its impact on kinetic growth. Methods. A rat model of rapid (portal vein ligation and parenchymal transection) and slow regeneration (portal vein ligation) was established. Portal vein flow and pressure data were collected. Liver regeneration was assessed in rats using computed tomography, proliferation with Ki‐67, and hypoxia with pimonidazole and HIF‐1&agr; staining. Results. The rat model confirmed acceleration of regeneration in portal vein ligation and parenchymal transection as well as the portal vein hyperflow seen in patients. Additionally, tissue hypoxia was observed after portal vein ligation and parenchymal transection, while little hypoxia staining was detected after portal vein ligation. To determine if hypoxia is a consequence or an inciting stimulus of rapid liver regeneration, we used a prolyl‐hydroxylase blocker to activate hypoxia signaling pathways in the slow model. This clearly accelerated slow to rapid liver regeneration. Inversely, abrogation of hypoxia led to a blunting of rapid growth to slow growth. The topical application of prolyl‐hydroxylase inhibitors on livers in rats induced spontaneous areas of regeneration. Conclusion. This study shows that pharmacologically induced hypoxic signaling accelerates liver regeneration similar to portal vein ligation and parenchymal transection. Hypoxia is likely an accelerator of liver regeneration. Also, prolyl‐hydroxylase inhibitors may be used to enhance liver regeneration pharmaceutically.

Propofol increases morbidity and mortality in a rat model of sepsis

IntroductionSevere sepsis is associated with approximately 50% mortality and accounts for tremendous healthcare costs. Most patients require ventilatory support and propofol is commonly used to sedate mechanically ventilated patients. Volatile anesthetics have been shown to attenuate inflammation in a variety of different settings. We therefore hypothesized that volatile anesthetic agents may offer beneficial immunomodulatory effects during the course of long-term intra-abdominal sepsis in rats under continuous sedation and ventilation for up to 24 hours.MethodsSham operation or cecal ligation and puncture (CLP) was performed in adult male Wistar rats followed by mechanical ventilation. Animals were sedated for 24 hours with propofol (7 to 20 mg/kg/h), sevoflurane, desflurane or isoflurane (0.7 minimal alveolar concentration each).ResultsSeptic animals sedated with propofol showed a mean survival time of 12 hours, whereas >56% of all animals in the volatile groups survived 24 hours (P <0.001). After 18 hours, base excess in propofol + CLP animals (−20.6 ± 2.0) was lower than in the volatile groups (isoflurane + CLP: -11.7 ± 4.2, sevoflurane + CLP: -11.8 ± 3.5, desflurane + CLP -14.2 ± 3.7; all P <0.03). Plasma endotoxin levels reached 2-fold higher levels in propofol + CLP compared to isoflurane + CLP animals at 12 hours (P <0.001). Also blood levels of inflammatory mediators (tumor necrosis factor-α, interleukin-1β, interleukin-10, CXCL-2, interferon-γ and high mobility group protein-1) were accentuated in propofol + CLP rats compared to the isoflurane + CLP group at the same time point (P <0.04).ConclusionsThis is the first study to assess prolonged effects of sepsis and long-term application of volatile sedatives compared to propofol on survival, cardiovascular, inflammatory and end organ parameters. Results indicate that volatile anesthetics dramatically improved survival and attenuate systemic inflammation as compared to propofol. The main mechanism responsible for adverse propofol effects could be an enhanced plasma endotoxin concentration, leading to profound hypotension, which was unresponsive to fluid resuscitation.

Sevoflurane reduces severity of acute lung injury possibly by impairing formation of alveolar oedema.

Pulmonary oedema is a hallmark of acute lung injury (ALI), consisting of various degrees of water and proteins. Physiologically, sodium enters through apical sodium channels (ENaC) and is extruded basolaterally by a sodium–potassium–adenosine–triphosphatase pump (Na+/K+‐ATPase). Water follows to maintain iso‐osmolar conditions and to keep alveoli dry. We postulated that the volatile anaesthetic sevoflurane would impact oedema resolution positively in an in‐vitro and in‐vivo model of ALI. Alveolar epithelial type II cells (AECII) and mixed alveolar epithelial cells (mAEC) were stimulated with 20 µg/ml lipopolysaccharide (LPS) and co‐exposed to sevoflurane for 8 h. In‐vitro active sodium transport via ENaC and Na+/K+‐ATPase was determined, assessing 22sodium and 86rubidium influx, respectively. Intratracheally applied LPS (150 µg) was used for the ALI in rats under sevoflurane or propofol anaesthesia (8 h). Oxygenation index (PaO2/FiO2) was calculated and lung oedema assessed determining lung wet/dry ratio. In AECII LPS decreased activity of ENaC and Na+/K+‐ATPase by 17·4% ± 13·3% standard deviation and 16·2% ± 13·1%, respectively. These effects were reversible in the presence of sevoflurane. Significant better oxygenation was observed with an increase of PaO2/FiO2 from 189 ± 142 mmHg to 454 ± 25 mmHg after 8 h in the sevoflurane/LPS compared to the propofol/LPS group. The wet/dry ratio in sevoflurane/LPS was reduced by 21·6% ± 2·3% in comparison to propofol/LPS‐treated animals. Sevoflurane has a stimulating effect on ENaC and Na+/K+‐ATPase in vitro in LPS‐injured AECII. In‐vivo experiments, however, give strong evidence that sevoflurane does not affect water reabsorption and oedema resolution, but possibly oedema formation.

The Effect of Hydroxyethyl Starches (hes 130/0.42 and Hes 200/0.5) on Activated Renal Tubular Epithelial Cells

BACKGROUND: Acute renal failure is a frequent complication of sepsis. Hydroxyethyl starch (HES) is widely used in the treatment of such patients. However, the effect of HES on renal function during sepsis remains controversial. We established an in vitro model of tumor necrosis factor-&agr; (TNF-&agr;)-stimulated human proximal tubular epithelial (HK-2) cells to assess the possible effects of HES 130/0.42 and HES 200/0.5 on these activated cells. METHODS: HK-2 cells were stimulated with TNF-&agr; in the presence or absence of HES 130/0.42 or 200/0.5. After 4, 10, and 18 h of incubation, monocyte chemoattractant protein-1 (MCP-1), a key chemoattractant for neutrophils and macrophages, was measured. In addition, viability and cytotoxicity assays were performed. RESULTS: MCP-1 expression was doubled upon TNF-&agr; exposure. In the presence of 2% and 4% HES 200/0.5 in 98% (96%) medium over a stimulation time period of 10 h and 18 h, the MCP-1 concentration was decreased between 26% and 56% (P < 0.05). TNF-&agr; stimulation resulted in a significant decrease of viability by 53%–63%, whereas viability decreased by only 32%–40% in coincubation with HES 130/0.42 (P < 0.005) and remained even less affected by TNF-&agr; in the presence of HES 200/0.5 (P < 0.001). The TNF-&agr;–induced cell death rate was attenuated in the presence of HES 200/0.5 (P < 0.05). CONCLUSIONS: This in vitro study shows that both HES products modulate cell injury upon inflammatory stimulation. The effect was more pronounced in the HES 200/0.5 group than for HES 130/0.42, suggesting a possible biological difference between the HES types.

Clinically relevant concentrations of lidocaine and ropivacaine inhibit TNFα-induced invasion of lung adenocarcinoma cells in vitro by blocking the activation of Akt and focal adhesion kinase

BACKGROUND Matrix-metalloproteinases (MMP) and cancer cell invasion are crucial for solid tumour metastasis. Important signalling events triggered by inflammatory cytokines, such as tumour necrosis factor α (TNFα), include Src-kinase-dependent activation of Akt and focal adhesion kinase (FAK) and phosphorylation of caveolin-1. Based on previous studies where we demonstrated amide-type local anaesthetics block TNFα-induced Src activation in malignant cells, we hypothesized that local anaesthetics might also inhibit the activation and/or phosphorylation of Akt, FAK and caveolin-1, thus attenuating MMP release and invasion of malignant cells. METHODS NCI-H838 lung adenocarcinoma cells were incubated with ropivacaine or lidocaine (1 nM-100 µM) in absence/presence of TNFα (20 ng ml(-1)) for 20 min or 4 h, respectively. Activation/phosphorylation of Akt, FAK and caveolin-1 were evaluated by Western blot, and MMP-9 secretion was determined by enzyme-linked immunosorbent assay. Tumour cell migration (electrical wound-healing assay) and invasion were also assessed. RESULTS Ropivacaine (1 nM-100 μM) and lidocaine (1-100 µM) significantly reduced TNFα-induced activation/phosphorylation of Akt, FAK and caveolin-1 in NCI-H838 cells. MMP-9 secretion triggered by TNFα was significantly attenuated by both lidocaine and ropivacaine (half-maximal inhibitory concentration [IC50]=3.29×10(-6) M for lidocaine; IC50=1.52×10(-10) M for ropivacaine). The TNFα-induced increase in invasion was completely blocked by both lidocaine (10 µM) and ropivacaine (1 µM). CONCLUSIONS At clinically relevant concentrations both ropivacaine and lidocaine blocked tumour cell invasion and MMP-9 secretion by attenuating Src-dependent inflammatory signalling events. Although determined entirely in vitro, these findings provide significant insight into the potential mechanism by which local anaesthetics might diminish metastasis.

Organ protection in allograft recipients: anesthetic strategies to reduce postoperative morbidity and mortality.

Purpose of reviewOrgan protection remains a primary objective in the anesthetic management of patients undergoing transplantation. An ongoing effort has been made to develop strategies to improve graft outcome and reduce postoperative morbidity and mortality, but trials have reported conflicting results. The aim of this review was to provide a comprehensive summary of the anesthetic management in transplant recipients and to identify current strategies for organ protection. Recent findingsDecreasing blood products requirements, intraoperative blood glucose control and adequate postoperative pain therapy may improve patient outcome. Vasopressors have been reported to reduce perioperative bleeding but might be associated with postoperative acute renal failure in liver transplantation. Early extubation may increase survival rates in recipients. These perioperative challenges, along with other protective strategies, have been addressed in 20 recently published studies: 10 randomized controlled trials, nine retrospective studies and one prospective study. SummaryThis review identified several promising strategies ensuring organ protection and improving patient outcome after solid organ transplantation. However, as outcomes were difficult to compare, further evidence will be needed before drawing firm conclusions.

Inflammatory Kidney and Liver Tissue Response to Different Hydroxyethylstarch (HES) Preparations in a Rat Model of Early Sepsis

Background Tissue hypoperfusion and inflammation in sepsis can lead to organ failure including kidney and liver. In sepsis, mortality of acute kidney injury increases by more than 50%. Which type of volume replacement should be used is still an ongoing debate. We investigated the effect of different volume strategies on inflammatory mediators in kidney and liver in an early sepsis model. Material and Methods Adult male Wistar rats were subjected to sepsis by cecal ligation and puncture (CLP) and assigned to three fluid replenishment groups. Animals received 30mL/kg of Ringer’s lactate (RL) for 2h, thereafter RL (75mL/kg), hydroxyethyl starch (HES) balanced (25mL/kg), containing malate and acetate, or HES saline (25mL/kg) for another 2h. Kidney and liver tissue was assessed for inflammation. In vitro rat endothelial cells were exposed to RL, HES balanced or HES saline for 2h, followed by stimulation with tumor necrosis factor-α (TNF-α) for another 4h. Alternatively, cells were exposed to malate, acetate or a mixture of malate and acetate, reflecting the according concentration of these substances in HES balanced. Pro-inflammatory cytokines were determined in cell supernatants. Results Cytokine mRNA in kidney and liver was increased in CLP animals treated with HES balanced compared to RL, but not after application of HES saline. MCP-1 was 3.5fold (95% CI: 1.3, 5.6) (p<0.01) and TNF-α 2.3fold (95% CI: 1.2, 3.3) (p<0.001) upregulated in the kidney. Corresponding results were seen in liver tissue. TNF-α-stimulated endothelial cells co-exposed to RL expressed 3529±1040pg/mL MCP-1 and 59±23pg/mL CINC-1 protein. These cytokines increased by 2358pg/mL (95% CI: 1511, 3204) (p<0.001) and 29pg/ml (95% CI: 14, 45) (p<0.01) respectively when exposed to HES balanced instead. However, no further upregulation was observed with HES saline. PBS supplemented with acetate increased MCP-1 by 1325pg/mL (95% CI: 741, 1909) (p<0.001) and CINC-1 by 24pg/mL (95% CI: 9, 38) (p<0.01) compared to RL. Malate as well as HES saline did not affect cytokine expression. Conclusion We identified HES balanced and specifically its component acetate as pro-inflammatory factor. How important this additional inflammatory burden on kidney and liver function is contributing to the sepsis-associated inflammatory burden in early sepsis needs further evaluation.