Inhalation of the BK(Ca)-opener NS1619 attenuates right ventricular pressure and improves oxygenation in the rat monocrotaline model of pulmonary hypertension.

BACKGROUND: Right heart failure is a fatal consequence of chronic pulmonary hypertension (PH). The development of PH is characterized by increased proliferation of vascular cells, in particular pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells. In the course of PH, an escalated right ventricular (RV) afterload occurs, which leads to increased perioperative morbidity and mortality. BK(Ca) channels are ubiquitously expressed in vascular smooth muscle cells and their opening induces cell membrane hyperpolarization followed by vasodilation. Moreover, BK activation induces anti-proliferative effects in a multitude of cell types. On this basis, we hypothesized that treatment with the nebulized BK channel opener NS1619 might be a therapy option for pulmonary hypertension and tested this in rats. METHODS: (1) Rats received monocrotaline injection for PH induction. Twenty-four days later, rats were anesthetized and NS1619 or the solvent was administered by inhalation. Systemic hemodynamic parameters, RV hemodynamic parameters, and blood gas analyses were measured before as well as 30 and 120 minutes after inhalation. (2) Rat PASMCs were stimulated with PDGF-BB in the presence and absence of NS1619. AKT, ERK1 and ERK2 activation were investigated by western blot analyses, and relative cell number was determined 48 hours after stimulation. RESULTS: Inhalation of a 12 µM and 100 µM NS1619 solution significantly reduced RV pressure without affecting systemic arterial pressure. Blood gas analyses demonstrated significantly reduced carbon dioxide and improved oxygenation in NS1619-treated animals pointing towards a considerable pulmonary shunt-reducing effect. In PASMC's, NS1619 (100 µM) significantly attenuated PASMC proliferation by a pathway independent of AKT and ERK1/2 activation. CONCLUSION: NS1619 inhalation reduces RV pressure and improves oxygen supply and its application inhibits PASMC proliferation in vitro. Hence, BK opening might be a novel option for the treatment of pulmonary hypertension.

Comparing hemodynamics, blood gas analyses and proinflammatory cytokines in endotoxemic and severely septic rats.

Lipopolysaccharide (LPS) is often used in short-term models of inflammation. Since endotoxemia and sepsis are different entities we have recently established a short-term sepsis model in rats induced by cecal ligation and incision (CLI). This retrospective study was conducted in order to identify similarities and differences between both experimental approaches. 32 anesthetized/ventilated male rats from the following four groups were analysed (each n=8): CTRL-group (0.9% NaCl i.v.); LPS-group (5mg/kg i.v.); SHAM-group (laparotomy); CLI-group (1.5 cm blade incision). Mean arterial blood pressure (MAP) and blood gas parameters (arterial base excess (BE) and pH) were continuously recorded. Total observation time was 300 min. Plasma samples were obtained afterwards. LPS and CLI induced significant arterial hypotension and metabolic acidosis compared to CTRL- or SHAM-group, respectively. Yet, between the LPS- and CLI-groups, there were no differences in MAP, BE and pH. LPS significantly induced IL-1ß, IL-6 and TNF-α in the plasma. In contrast, CLI showed a clear tendency towards increased IL-1ß and IL-6 plasma levels and did not affect TNF-α. Our results indicate that the CLI sepsis model is suitable for short-term investigations on hemodynamic alterations and blood gas analyses during sepsis. 300 min after the proinflammatory insult, plasma concentrations of IL-1ß and IL-6 in the plasma remain considerably lower after CLI compared to endotoxemia. Low TNF-α concentrations 300 min after sepsis induction could be interpreted as considerable immunosuppression during CLI sepsis.

Effects of short-term infusion of lipid emulsions on pro-inflammatory cytokines and lymphocyte apoptosis in septic and non-septic rats.

Long-term administration of PUFA is known to modulate immune functions and apoptotic pathways depending on the respective amount of n-6 and n-3 fatty acids (FA). Data on short-term effects on apoptotic pathways are rare. Apoptosis of splenic lymphocytes is the hallmark of detrimental sepsis. Therefore, we aimed to compare the immediate effects of parenterally administered n-6-enriched soyabean oil (SO)- and n-3-enriched fish oil (FO)-based lipid emulsions after laparotomy (LAP; sham procedure) and after induction of acute, severe sepsis by caecal ligation and incision. After 390 min of observation time, plasma was analysed for IL-1ß, IL-6 and NEFA. Apoptosis in splenic lymphocytes was quantified by Annexin-V expression. After LAP, infusion of both FO and SO did not change cytokine concentrations. Sepsis increased both cytokines. FO but not SO further augmented the rise. After LAP, SO increased NEFA, and both lipid emulsions reduced free arachidonic acid (AA). Sepsis resulted in a dramatic decrease in NEFA and AA. The drop in NEFA and AA was prevented by both SO and FO. In addition, FO resulted in an increased concentration of n-3 FA under both conditions. Infusion of both lipid emulsions induced apoptosis in splenic lymphocytes after LAP. Sepsis-induced apoptosis was not further enhanced by FO or SO. The present study shows that short-term administration of FO as opposed to SO caused pro-inflammatory effects during sepsis. Moreover, short-term administration of both SO and FO suffices to induce apoptosis in splenic lymphocytes. Finally, SO and FO do not further enhance sepsis-induced splenic apoptosis.

Protective properties of inhaled IL-22 in a model of ventilator-induced lung injury.

High-pressure ventilation induces barotrauma and pulmonary inflammation, thus leading to ventilator-induced lung injury (VILI). IL-22 has both immunoregulatory and tissue-protective properties. Functional IL-22 receptor expression is restricted to nonleukocytic cells, such as alveolar epithelial cells. When applied via inhalation, IL-22 reaches the pulmonary system directly and in high concentrations, and may protect alveolar epithelial cells against cellular stress and biotrauma associated with VILI. In A549 lung epithelial cells, IL-22 was able to induce rapid signal transducer and activator of transcription (STAT)-3 phosphorylation/activation, and hereon mediated stable suppressor of cytokine signaling (SOCS) 3 expression detectable even 24 hours after onset of stimulation. In a rat model of VILI, the prophylactic inhalation of IL-22 before induction of VILI (peak airway pressure = 45 cm H(2)O) protected the lung against pulmonary disintegration and edema. IL-22 reduced VILI-associated biotrauma (i.e., pulmonary concentrations of macrophage inflammatory protein-2, IL-6, and matrix metalloproteinase 9) and mediated pulmonary STAT3/SOCS3 activation. In addition, despite a short observation period of 4 hours, inhaled IL-22 resulted in an improved survival of the rats. These data support the hypothesis that IL-22, likely via activation of STAT3 and downstream genes (e.g., SOCS3), is able to protect against cell stretch and pulmonary baro-/biotrauma by enhancing epithelial cell resistibility.

Cuff overinflation and endotracheal tube obstruction: case report and experimental study.

BACKGROUND: Initiated by a clinical case of critical endotracheal tube (ETT) obstruction, we aimed to determine factors that potentially contribute to the development of endotracheal tube obstruction by its inflated cuff. Prehospital climate and storage conditions were simulated. METHODS: Five different disposable ETTs (6.0, 7.0, and 8.0 mm inner diameter) were exposed to ambient outside temperature for 13 months. In addition, every second of these tubes was mechanically stressed by clamping its cuffed end between the covers of a metal emergency case for 10 min. Then, all tubes were heated up to normal body temperature, placed within the cock of a syringe, followed by stepwise inflation of their cuffs to pressures of 3 kPa and > or =12 kPa, respectively. The inner lumen of the ETT was checked with the naked eye for any obstruction caused by the external cuff pressure. RESULTS: Neither in tubes that were exposed to ambient temperature (range: -12 degrees C to +44 degrees C) nor in those that were also clamped, visible obstruction by inflated cuffs was detected at any of the two cuff pressure levels. CONCLUSIONS: We could not demonstrate a critical obstruction of an ETT by its inflated cuff, neither when the cuff was over-inflated to a pressure of 12 kPa or higher, nor in ETTs that had been exposed to unfavorable storage conditions and significant mechanical stress.

A point-of-care assessment of the effects of desmopressin on impaired platelet function using multiple electrode whole-blood aggregometry in patients after cardiac surgery.

BACKGROUND: Blood loss after cardiac surgery can be caused by acquired platelet dysfunction after cardiopulmonary bypass. Monitoring of platelet function is clinically important for the identification of patients experiencing such platelet dysfunction. 1-Deamino-8-D-arginine vasopressin (desmopressin acetate, DDAVP) has been shown to augment platelet function and to reduce blood loss in patients with platelet dysfunction. In this study, we examined the feasibility of whole blood multiple electrode aggregometry (MEA) for the detection of cardiopulmonary bypass-induced platelet dysfunction and investigated its ability to monitor DDAVP treatment. METHODS: Fifty-eight consecutive patients with blood loss exceeding 150 mL/h in the first 2 consecutive hours after cardiac surgery were screened for suspected isolated platelet dysfunction. Twenty-two patients had suspected isolated platelet dysfunction and were enrolled in the study. Platelet dysfunction was assumed if conventional coagulation analyses (platelet count, activated partial thromboplastin time, international normalized ratio, and fibrinogen) did not show abnormal values as defined for transfusion of allogenic blood products, and no surgical cause of bleeding was suspected. Eleven patients received 0.3 microg/kg DDAVP, and 11 patients received no therapy in a nonrandomized manner. MEA was performed after stimulation with thrombin receptor-activating peptide (TRAPtest, 32 microM), adenosine diphosphate (ADPtest, 6.4 microM), and arachidonic acid (ASPItest, 0.5 mM) before and 2 hours after intervention. Conventional laboratory variables were recorded. The Mann-Whitney test was used to detect differences between the groups, and the Wilcoxon test was used to detect differences before and after intervention. RESULTS: All enrolled patients showed platelet dysfunction that manifested as impaired platelet aggregation in MEA before intervention. After the intervention, platelet function improved in the DDAVP group (49 U [30/72 U], median [25th/75th percentile] postintervention vs 15 U [8/21 U] preintervention for the ASPItest [P < 0.001]; 35 U [24/54 U] vs 14 U [7/28 U] for the ADPtest [P = 0.002]; and 85 U [66/115 U] vs 64 U [26/88 U] for the TRAPtest [P = 0.007]). In contrast, MEA remained unchanged in the control group (22 U [10/50 U] postintervention vs 33 U [14/57 U] preintervention for the ASPItest [P = 0.175]; 17 U [12/20 U] vs 14 U [10/28 U] for the ADPtest [P = 0.147]; and 65 U [41/89 U] vs 57 U [30/91 U] for the TRAPtest [P = 0.123]). CONCLUSIONS: Impaired platelet function after cardiac surgery can be assessed at the bedside using MEA. The effect of DDAVP on impaired platelet function can also be detected as significant improvement in platelet aggregation to all activators. This device might be helpful for the identification of patients who may benefit from DDAVP therapy.

Effect of inhaled and intravenous lidocaine on inflammatory reaction in endotoxaemic rats.

BACKGROUND AND OBJECTIVE: Systemically administered lidocaine has been shown to have anti-inflammatory properties. Inhalation is an attractive way of application because of high pulmonary compound concentrations and potentially fewer systemic side effects. The aim of this study was to clarify whether inhaled or, likewise, intravenous lidocaine can attenuate the inflammatory response in a model of experimental endotoxaemia in the rat. METHODS: Animals randomly received (nine animals in each group) lidocaine, either aerosolized 4 mg kg(-1) (Lid(Ae4.0)) and 0.4 mg kg(-1) (Lid(Ae0.4)) or 4 mg kg(-1) intravenously (Lid(iv)) before intravenous injection of 5 mg kg(-1) lipopolysaccharide (LPS). Administration of lidocaine was repeated after 2 h. Additional control animals were observed either without (sham) or with the infusion of LPS. Following 5 h of experimental endotoxaemia, the concentrations of tumour necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta) and IL-6 were measured in bronchoalveolar lavage fluid and blood plasma. Release of nitrite in ex-vivo cultured alveolar macrophages was measured by Griess assay. RESULTS: Bronchoalveolar lavage fluid levels of IL-1beta and TNFalpha in Lid(Ae4.0) (IL-1beta, -47%; TNFalpha, -41%; P < 0.05) and Lid(iv) (IL-1beta, -55%; TNFalpha, -54%; P < 0.05) but not in Lid(Ae0.4) were significantly lower than in LPS. Plasma cytokine levels were not attenuated. Nitrite was found to be significantly reduced in Lid(Ae4.0) (-46%), Lid(Ae0.4) (-39%) and Lid(iv) (-41%) when compared with LPS (P < 0.05, respectively). CONCLUSION: Pretreatment of endotoxaemic rats either with Lid(Ae4.0) or with Lid(iv) attenuated the levels of proinflammatory mediators in bronchoalveolar lavage fluid. Plasma cytokine levels were not affected. Nebulized lidocaine (0.4 mg kg(-1)) inhibited the nitrite release but did not affect the cytokine levels.

Sevoflurane and isoflurane decrease TNF-alpha-induced gene expression in human monocytic THP-1 cells: potential role of intracellular IkappaBalpha regulation.

The nuclear factor (NF)-kappaB/inhibitory (I)kappaBalpha pathway is one of the most important intracellular signal transduction pathways during inflammation which is induced by a variety of major early response cytokines. Recent studies suggest that volatile anesthetics interfere with inflammatory cytokine production through inhibition of intracellular signal transduction pathways. We, therefore, aimed to investigate the effects of the volatile anesthetics sevoflurane and isoflurane on NF-kappaB/IkappaBalpha-dependent intracellular signal transduction in human monocytic THP-1 cells induced by tumor necrosis factor-alpha (TNF-alpha) and production of interleukin-8 (IL-8) and downstream heme oxygenase-1 (HO-1). THP-1 cells, a human monocytic cell line, were used in an in vitro model which enables the exposure to volatile anesthetics. Using this model, THP-1 cells were subjected to sevoflurane or isoflurane exposure (1 MAC each) and were stimulated with TNF-alpha (50 or 100 ng/ml). Compared to untreated cells, expression of intracellular HO-1-protein and release of IL-8 into cell culture supernatants and corresponding mRNA expression were attenuated in THP-1 cells exposed to sevoflurane and isoflurane, respectively. Moreover, translocation of NF-kappaB and degradation of IkappaBalpha were markedly reduced by both anesthetics. Notably, under unstimulated conditions, exposure to sevoflurane induced a sustained upregulation of the IkappaBalpha content in THP-1 cells. We demonstrated inhibition of TNF-alpha-induced gene expression and release of IL-8 and HO-1 in human monocytic THP-1 cells exposed to both volatile anesthetics. This was associated with an upregulated intracellular IkappaBalpha content followed by decreased NF-kappaB translocation. This was more sustained during exposure to sevoflurane and may provide an additional intracellular mechanism for the anti-inflammatory effects associated with sevoflurane administration.

Effects of intravenous and inhaled levosimendan in severe rodent sepsis.

PURPOSE: We aimed at comparing the effects of intravenous (i.v.) and inhaled (inh.) levosimendan (LEVO) on survival, inflammatory cytokines and the apoptotic mediator caspase-3 in a rat model of severe sepsis induced by cecal ligation and incision (CLI). METHODS: Twenty-eight anesthetized/ventilated male Sprague-Dawley rats (body weight 528 +/- 20 g) underwent laparotomy. Cecal mobilisation served as control (SHAM, n = 7). In all other groups, severe sepsis was induced by CLI. No further intervention occurred in the CLI-group (n = 7). 180 min after CLI, 24 microg/kg i.v. LEVO was administered in the CLI + LEVO-IV-group (n = 7), and 24 microg/kg inh. LEVO was administered via jet nebulizer in the CLI + LEVO-INH-group (n = 7). RESULTS: CLI induced arterial hypotension, with i.v. and inh. LEVO attenuating blood pressure decrease over 390 min [CLI 34(31/50), CLI + LEVO-IV 82(69/131)*, CLI + LEVO-INH 78(62/85)* mmHg; median(25/75% quartile), *P < 0.05]. CLI induced metabolic acidosis. I.v. and inh. LEVO avoided arterial pH [CLI 7.18(7.16/7.2), CLI + LEVO-IV 7.27(7.24/7.31)*, CLI + LEVO-INH 7.26(7.24/7.28)*] and base excess deterioration [CLI -19(-21.8/-17.9), CLI + LEVO-IV -13(-14.8/-12)*, CLI + LEVO-INH -12.7(-14/-12.2)* mmol/l]. Overall mortality in the CLI-group was 57% compared to 0%* in both LEVO-treated groups after 390 min. LEVO administration significantly attenuated the increase in proinflammatory interleukin (IL)-1beta [CLI 896(739/911), CLI + LEVO-IV 302(230/385)*, CLI + LEVO-INH 346(271/548) pg/ml] and IL-6 [CLI 35651(31413/35816), CLI + LEVO-IV 21156(18397/28026), CLI + LEVO-INH 13674(10105/24843) pg/ml] in the plasma and reduced cleaved caspase-3 expression in the spleen. CONCLUSIONS: In a rat model of severe sepsis induced by CLI, i.v. and inh. LEVO equally attenuated arterial hypotension, metabolic acidosis and prolonged survival. Moreover, i.v. and inh. LEVO inhibited proinflammatory mediator release and reduced splenic caspase-3 expression.

Inhaled IL-10 reduces biotrauma and mortality in a model of ventilator-induced lung injury.

BACKGROUND: High-pressure ventilation induces barotrauma and pulmonary inflammation, thus leading to ventilator-induced lung injury (VILI). By limiting the pulmonal inflammation cascade the anti-inflammatory cytokine interleukin (IL)-10 may have protective effects. Via inhalation, IL-10 reaches the pulmonary system directly and in high concentrations. METHODS: Thirty six male, anesthetized and mechanically ventilated Sprague-Dawley rats were randomly assigned to the following groups (n=9, each): SHAM: pressure controlled ventilation with p(max)=20cmH(2)O, PEEP=4; VILI: ventilator settings were changed for 20min to p(max)=45cmH(2)O, PEEP=0; IL-10(high): inhalation of 10microg/kg IL-10 prior to induction of VILI; and IL-10(low): inhalation of 1microg/kg IL-10 prior to induction of VILI. All groups were ventilated and observed for 4h. RESULTS: High-pressure ventilation increased the concentrations of macrophage inflammatory protein (MIP)-2 and IL-1beta in bronchoalveolar lavage fluid (BALF) and plasma. This effect was reduced by the inhalation of IL-10 (10microg/kg). Additionally, IL-10 increased the animal survival time (78% vs. 22% 4-h mortality rate) and reduced NO-release from ex vivo cultured alveolar macrophages. Moreover, VILI-induced pulmonary heat shock protein-70 expression was reduced by IL-10 aerosol in a dose-dependent manner. Similarly, the activation of matrix metalloproteinase (MMP)-9 in BALF was reduced dose-dependently by IL-10. IL-10-treated animals showed a lower macroscopic lung injury score and less impairment of lung integrity and gas exchange. CONCLUSIONS: Prophylactic inhalation of IL-10 improved survival and reduced lung injury in experimental VILI. Results indicate that this effect may be mediated by the inhibition of stress-induced inflammation and pulmonary biotrauma.

Cecal ligation and incision: an acute onset model of severe sepsis in rats.

BACKGROUND: Sepsis is a leading cause of death among critically ill patients. Up to now, severe sepsis with acute onset in animals has been induced mainly through injection of single bacteria species or endotoxin and not through a surgical procedure, which might adequately mirror the situation in septic patients. We therefore aimed to establish a surgical model of severe sepsis in rodents fulfilling international sepsis criteria. MATERIALS AND METHODS: Twenty-eight anesthetized/ventilated Sprague Dawley rats underwent laparotomy and cecal mobilization. The cecum was either replaced into the abdomen (SHAM, n = 14) or the cecum and the mesenteric blood vessels were ligated, and the cecum was opened through a 1.5 cm blade incision (cecal ligation and incision, CLI, n = 14). RESULTS: Within 390 min, mortality was 0% (SHAM) and 50% (CLI), respectively. Compared with SHAM, CLI resulted in a 43% reduction of mean arterial blood pressure and in severe metabolic acidosis as measured by arterial base excess and pH. CLI led to a 15-fold increase in mononuclear cell population and to a 5-fold accumulation of nitrite in peritoneal lavage. Abdominal swabs from the Douglas cavity in CLI-animals showed gram-positive and gram-negative bacterial growth on agar compared with sterile swabs from SHAM-animals. In CLI-animals, plasma IL-1beta level was increased to 435 pg/mL (SHAM: 10 pg/mL) and plasma IL-6 level to 19718 pg/mL (SHAM: 832 pg/mL). CONCLUSIONS: CLI causes bacterial peritonitis with subsequent systemic inflammation and organ dysfunction. Thus, CLI mimics clinical sepsis and provides a surgical short term model of severe sepsis in rodents.

Inhaled levosimendan reduces mortality and release of proinflammatory mediators in a rat model of experimental ventilator-induced lung injury.

OBJECTIVES: Mechanical ventilation during critical care can cause structural and functional disturbances in the lung with subsequent release of proinflammatory mediators, termed ventilator-induced lung injury (VILI). VILI progressively provokes decreased efficiency of gas exchange with subsequent hypoxic pulmonary vasoconstriction leading to cardiopulmonary alterations, such as pulmonary hypertension and right heart failure. We therefore aimed to evaluate whether inhalation therapy with levosimendan, a calcium-sensitizer with pulmonary vasodilating properties, could attenuate VILI and improve short-term survival in a rat experimental model. DESIGN: Experimental animal model. SETTING: University hospital. SUBJECTS: Forty male Sprague-Dawley rats. INTERVENTIONS: Rats were randomly treated as follows (n = 8, each group): 1) inhalation of the solvent only before induction of VILI, no further intervention; 2) inhalation of 240 microg of levosimendan before VILI induction; 3) inhalation of 24 microg of levosimendan before VILI induction; 4) intravenous administration of 24 microg/kg levosimendan before VILI induction; 5) control group with surgical preparation only. All groups were observed for 4 hrs. MEASUREMENTS AND MAIN RESULTS: After 4 hrs following induction of VILI, levels of interleukin-1beta and macrophage inflammatory protein-2 in plasma and bronchoalveolar lavage fluid were analyzed by enzyme-linked immunosorbent assay. Nitric oxide release from alveolar macrophages was measured by Griess assay. Content of matrix metalloproteinase-2 and matrix metalloproteinase-9 in bronchoalveolar lavage fluid was analyzed by gelatin zymography. Inhalation of 240 microg of levosimendan significantly improved survival after 4 hrs and mean arterial blood pressure compared with VILI only. Additionally, inhalation of 240 microg and infusion of 24 microg/kg levosimendan significantly reduced the release of interleukin-1beta, the nitric oxide release from alveolar macrophages, macrophage inflammatory protein-2 in plasma, and the macrophage inflammatory protein-2 and matrix metalloproteinase-9 content in bronchoalveolar lavage fluid compared with VILI only. CONCLUSIONS: Our study demonstrates that prophylactic inhalation of 240 microg of levosimendan improves survival and reduces release of inflammatory mediators in our experimental model of VILI. This might affect the clinical prophylaxis and treatment of VILI.

Short-term exposure to high-pressure ventilation leads to pulmonary biotrauma and systemic inflammation in the rat.

Though often lifesaving, mechanical ventilation itself bears the risk of lung damage [ventilator-induced lung injury (VILI)]. The underlying molecular mechanisms have not been fully elucidated, but stress-induced mediators seem to play an important role in biotrauma related to VILI. Our purpose was to evaluate an animal model of VILI that allows the observation of pathophysiologic changes along with parameters of biotrauma. For VILI induction, rats (n=16) were ventilated with a peak airway pressure (pmax) of 45 cm H2O and end-expiratory pressure (PEEP) of 0 for 20 min, followed by an observation time of 4 h. In the control group (n=8) the animals were ventilated with a pmax of 20 cm H2O and PEEP of 4. High-pressure ventilation resulted in an increase in paCO2 and a decrease in paO2 and mean arterial pressure. Only 4 animals out of 16 survived 4 h and VILI lungs showed severe macroscopic and microscopic damage, oedema and neutrophil influx. High-pressure ventilation increased the cytokine levels of macrophage inflammatory protein-2 and IL-1beta in bronchoalveolar lavage and plasma. VILI also induced pulmonary heat shock protein-70 expression and the activity of matrix metalloproteinases. The animal model used enabled us to observe the effect of high-pressure ventilation on mortality, lung damage/function and biotrauma. Thus, by combining barotrauma with biotrauma, this animal model may be suitable for studying therapeutical approaches to VILI.

Norepinephrine and vasopressin counteract anti-inflammatory effects of isoflurane in endotoxemic rats.

Volatile anesthetics such as isoflurane have been shown to offer anti-inflammatory effects during experimental endotoxemia whereas the alpha-adrenergic vasopressor norepinephrine exhibits proinflammatory properties on systemic cytokine release under the same conditions. However, during major surgery and in patients with systemic inflammatory response syndrome or sepsis both agents are frequently administered concurrently. We therefore aimed to investigate the influence of preexisting i.v. administration of noradrenaline or vasopressin on the anti-inflammatory effects of isoflurane during experimental endotoxemia. Anesthetized, ventilated Sprague-Dawley rats (n=7 per group) were randomly treated. In the LPS-only group, animals received lipopolysaccharide (LPS, 5 mg/kg, i.v.) with no further specific treatment. In the LPS-isoflurane group, isoflurane inhalation at 1 MAC was initiated simultaneously with induction of endotoxemia (LPS 5 mg/kg, i.v.). Animals in the LPS-isoflurane-norepinephrine group received norepinephrine infusion at 50 microg/kg/h 10 min prior to injection of LPS and inhalation of isoflurane. In the LPS-isoflurane-vasopressin group, vasopressin was administered at 0.5 IE/kg/h 10 min prior to LPS and isoflurane. In the LPS-norepinephrine and the LPS-vasopressin groups the infusion of each vasopressor was started prior to LPS injection without any application of isoflurane. A Sham group served as the control. After 4 h of endotoxemia, plasma levels of TNFalpha, IL-1beta and IL-10 were measured. Alveolar macrophages (AM) were cultured ex vivo for nitrite assay. Induction of endotoxemia resulted in a significant rise in measured plasma cytokines and nitrite production from cultured AM. Inhalation of isoflurane significantly attenuated plasma levels of TNFalpha (-65%) and IL-1beta (-53%) compared to the LPS-only group whereas it had no effect on nitrite production from cultured AM. Preexisting infusions of norepinephrine or vasopressin abolished the anti-inflammatory effects of isoflurane. The data demonstrate that the administration of norepinephrine or vasopressin both counteracted the anti-inflammatory effects of inhaled isoflurane on proinflammatory cytokine release during experimental endotoxemia in rats.

Targeting caspase-1 by inhalation-therapy: effects of Ac-YVAD-CHO on IL-1 beta, IL-18 and downstream proinflammatory parameters as detected in rat endotoxaemia.

OBJECTIVE: We set out to investigate whether the nebulized and inhaled specific caspase-1 inhibitor Ac-YVAD-CHO has the potential to attenuate the pulmonary and systemic release of the caspase-1-dependent cytokines interleukin-1 beta (IL-1 beta) and interleukin-18 (IL-18) as well as their downstream enzymes iNOS and COX-2 in rat experimental endotoxaemia. DESIGN AND SETTING: Controlled, randomized animal study in a university research facility. SUBJECT: Male Sprague-Dawley rats (n=32) were randomly treated as follows: Inhaled Ac-YVAD-CHO was administered in eight rats at a inhaled total dosage of 5 mg and in eight rats at a inhaled total dose of 0.5 mg before infusion of lipopolysaccharide (LPS; 5 mg/kg, i.v.). Eight animals received LPS only. Eight animals served as controls without endotoxaemia. MEASUREMENTS AND RESULTS: After 4h of endotoxaemia, levels of IL-1 beta, IL-18 and TNF-alpha in plasma and bronchoalveolar fluid (BALF) were analyzed. Nitric oxide (NO) release from alveolar macrophages was measured by Griess assay. Amounts of iNOS protein in alveolar macrophages and COX-2 protein in lung homogenates were determined by Western blotting. Significant reductions in release of IL-1 beta (-58%, p<0.05) and IL-18 (-51%, p<0.05) in plasma and IL-1 beta (-59%, p<0.05) in BALF were found in animals pretreated with inhaled caspase-1 inhibitor compared with animals without therapy. Expression of iNOS in alveolar macrophages and COX-2 in lung tissue was concurrently decreased in the treatment groups compared with control animals. CONCLUSIONS: Our data demonstrate that administration of the caspase-1 inhibitor Ac-YVAD-CHO by inhalation is able to reduce the pulmonary and systemic release of proinflammatory mediators in rat endotoxaemia. These results further underscore that inhalation may constitute an effective route of anti-inflammatory drug administration, beneficial in the clinical setting of ARDS.

Prehospital emergency endotracheal intubation using the Bonfils intubation fiberscope.

Among all prehospital emergency intubations, difficulties occur in 7-10%. Furthermore, intubation conditions often worsen when the cervical spine is immobilized in trauma patients. We report on six patients in whom the Bonfils intubation fiberscope, a reusable, rigid fiberoptic device, was used for emergency endotracheal intubation in the field. Three of these patients had an anticipated or unanticipated difficult airway: two trauma patients with immobilized cervical spine and one patient in cardiac arrest in whom direct laryngoscopy failed twice. Endotracheal intubation with the Bonfils intubation fiberscope was successful in all cases in the first attempt. The Bonfils intubation fiberscope therefore demonstrated its value as an additional airway management device in both emergency and prehospital settings.

Comparison of direct and video-assisted views of the larynx during routine intubation.

OBJECTIVE: To compare the direct and indirect (video monitor) views of the glottic opening using a new Macintosh blade that is modified to provide a video image of airway structures during laryngoscopy. DESIGN: Prospective multicenter trial. SETTING: 11 university-affiliated hospitals. PATIENTS: 867 adults undergoing elective surgery requiring general anesthesia and tracheal intubation. INTERVENTIONS: Patients received general anesthesia and were paralyzed. Direct laryngoscopy was supervised by one of the investigators at each institution. The best possible view was obtained with a Macintosh video laryngoscope during direct vision using standard techniques such as external laryngeal manipulation and backward, upward, and rightward pressure, if necessary. The laryngoscopist then looked at the video monitor and performed any necessary maneuvers to obtain the best view on the video monitor. Thus, 2 assessments were made during the same laryngoscopy (direct naked-eye view vs video monitor view). Tracheal intubation was then performed using the monitor view. Glottic views were rated according to the Cormack-Lehane scoring system, as modified by Yentis and Lee. A questionnaire was completed for each patient. MEASUREMENTS AND MAIN RESULTS: Data from 865 patients were suitable for analysis. Visualization was considered easy (Cormack-Lehane score<3) in 737 patients and difficult (Cormack-Lehane score=3 or 4) in 21 for both direct and video-assisted views. In 7 patients, the view was considered easy during direct visualization yet difficult on the video monitor view. On the other hand, the view was considered difficult in 100 patients during direct visualization yet easy on the video monitor view (P<0.001). CONCLUSIONS: Video-assisted laryngoscopy provides an improved view of the larynx, as compared with direct visualization. This technique may be useful for cases of difficult intubation and reintubation as well as for teaching laryngoscopy and intubation.

Desflurane differentially affects the release of proinflammatory cytokines in plasma and bronchoalveolar fluid of endotoxemic rats.

Previous studies have indicated that volatile anaesthetics can attenuate the inflammatory response to lipopolysaccharide (LPS) and other proinflammatory stimuli in vitro and in vivo. Thus far, no studies are available on the influences of desflurane on the cytokine-release. We therefore aimed to investigate the effects of desflurane on the systemic and pulmonary release of proinflammatory cytokines in endotoxemic rats. Eighteen anaesthetized and ventilated Sprague-Dawley rats were randomly assigned to the following groups: LPS-only: Six animals received LPS (5 mg/kg, i.v.) with no further intervention. LPS-Desflurane: Six animals received continuous inhalation of 1MAC Desflurane before and during endotoxemia with LPS (5 mg/kg, i.v.). Sham: Six animals served as control without inhalation of desflurane and endotoxemia. After 4 h, levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in plasma and bronchoalveolar fluid were analyzed. Nitrite production as a readout for nitric oxide (NO) release from alveolar macrophages was measured by Griess assay. IkappaB-alpha degradation and iNOS-protein in macrophage homogenates were determined by Western Blotting. Inhalation of desflurane during endotoxemia showed a significant decrease in release of the proinflammatory cytokines TNF-alpha (-61%, P< or =0.05) and IL-1beta (-47%, P< or =0.05) in plasma as compared to LPS-only group, whereas the release of IL-6 was not significantly affected by desflurane. Within the lung, the NO-release was notably increased in supernatants of cultured alveolar macrophages from desflurane-group compared to both LPS-only and Sham group. IkappaB-alpha degradation in alveolar macrophages was impaired in the Desflurane-group as compared to the LPS-only group. Our data implicate that inhalation of 1MAC Desflurane during experimental endotoxemia differentially affects the inflammatory response in rats.

Interleukin-10 aerosol reduces proinflammatory mediators in bronchoalveolar fluid of endotoxemic rat.

OBJECTIVE: We aimed to clarify if inhaled interleukin (IL)-10 attenuates pulmonary and systemic inflammation as indicated by reduced content of proinflammatory mediators in bronchoalveolar lavage fluid (BALF) and plasma in experimental endotoxemia in the rat. DESIGN: Laboratory experiment. SETTING: University research institute. SUBJECTS: Anesthetized, ventilated rats (sd, 550 +/- 50 g). INTERVENTIONS: Rats were randomly treated as follows: Nebulized IL-10 (calculated deposition fraction, 0.1 microg/lung) was administered in eight rats before infusion of lipopolysaccharide (5 mg/kg, intravenously). Eight animals received the same insult with no further treatment. Eight rats served as controls without endotoxemia but with aerosolized saline. MEASUREMENTS AND MAIN RESULTS: BALF and plasma levels of tumor necrosis factor (TNF)-alpha, IL-1beta, IL-6, interferon (IFN)-gamma, and RANTES were analyzed. Alveolar macrophages were cultured ex vivo for nitrite assay. In those animals treated with IL-10-aerosol, BALF levels of proinflammatory cytokines were reduced significantly compared with animals without IL-10 therapy (TNF-alpha, -87%; IL-1beta, -73%; IL-6, -44%; IFN-gamma, -39%; RANTES, -84%). In addition, nitrite release from cultured alveolar macrophages was suppressed by IL-10 inhalation (-96%). With the exception of TNF-alpha, similar results were observed for plasma levels of proinflammatory cytokines. CONCLUSIONS: The present data indicate that nebulized IL-10 reached the lungs in therapeutic effective concentrations and elicited anti-inflammatory effects on immunocompetent cells that are comparable to those already known from its intravenous administration in experimental endotoxemia.

A brief exposure to isoflurane (50 s) significantly impacts on plasma cytokine levels in endotoxemic rats.

Induction of anesthesia by inhalation of isoflurane is a frequently used procedure in models of immunological diseases. Here we investigated effects of a brief exposure to isoflurane on cytokine production by endotoxemic rats. Anesthesia was either performed by pentobarbital/fentanyl without or accompanied by a 50-s inhalation pretreatment with isoflurane. After 4 h of endotoxemia, plasma levels of TNFalpha, IL-1beta, and RANTES were determined. Isoflurane significantly inhibited plasma levels of TNFalpha and IL-1beta by 69.3% and 61.8%, respectively. Levels of RANTES were similarly reduced by 43.1% (n.s.). Moreover, isoflurane significantly attenuated basal nitrite production by alveolar macrophages isolated from endotoxemic rats (by 59.4%). Thus, we confirm anti-inflammatory properties of isoflurane and beyond that clearly demonstrate that even a short exposure (<1 min) can profoundly affect pro-inflammatory parameters in experimental endotoxemia. These unforeseen observations suggest that short-term inhalation of isoflurane for induction of anesthesia may be an unsuitable procedure particularly in animal models of acute inflammation.