Signs Of Acute Lung Injury Research Articles

Липосомальная форма дексаметазона в коррекции экспериментального острого повреждения легких

Objective. To investigate the possibility of pharmacological correction of acute lung injury of aspiration genesis with a liposomal form of dexamethasone in experiment. Materials and methods. For the experiment, simple liposomes were prepared from phosphatidylcholine and cholesterol with an average size of 320±50 nm and a dexamethasone concentration of 2.98±0.02 mg/ml. The study used outbred white rats, divided into four groups of 16 animals. 1st group Control (without experimental therapy), 2nd group - Experiment 1, where a solution of dexamethasone was injected intravenously at a dose of 6 mg/kg, 3rd group - Experiment 2, where an intravenous combination of dexamethasone solution (6 mg/kg) and hypertonic (7.5%) NaCl solution was administered once, and group 4 - Experiment 3, where liposomes with dexamethasone (6 mg/kg) were injected intravenously once in hypertensive (7.5%) NaCl solution. The main functional parameters of the animals (heart rate, blood pressure, saturation of hemoglobin with oxygen, partial pressure of blood oxygen and respiration rate) were subject to analysis. Functional parameters were analyzed before modeling acute lung injury and after 5 min, 1, 4, 24 hours, and 6 days. At the end of the experiment (day 6) the degree of pulmonary edema and histological signs of acute lung injury were assessed. Morphology was assessed quantitatively in each group. Results. The study found that liposomal dexamethasone in hypertonic NaCl solution, when administered intravenously, was more effective than aqueous dexamethasone solution in correcting functional impairment in acute lung injury. The combination of hypertonic sodium chloride solution with dexamethasone more markedly increases blood pressure and reduces the degree of pulmonary oedema. In acidine pepsin aspiration, liposomal dexamethasone in hypertonic NaCl solution most effectively increased animal survival. Conclusion. Compared with dexamethasone in hypertonic NaCl solution, liposomal dexamethasone is more effective in increasing animal survival and protecting lung tissue from aspiration damage by acidine pepsin.

THE MORPHOLOGY OF THE LUNGS AT THE EXPERIMENTAL ACUTE INJURY AND ITS PHARMACOCORRECTION

The study of lung morphology under the influence of various environmental factors is of great interest for various areas of medicine and biology. The study of pathological changes in the respiratory part of the lung of rats with aspiration acute injury and the action of pharmacological correction was carried out. Acetone was used as a damaging agent, and HyperHAES was used as a means of pharmacological correction, containing 7.2% NaCl solution in combination with 6% hydroxyethyl starch, as well as a liposomal form of N-acetylcysteine, which was administered to experimental animals once intravenously after induction of acute lung injury. The control group of animals received antibiotic therapy. The staining of the slides was carried out using hematoxylin and eosin. A quantitative assessment of the histological signs of lung tissue damage was carried out. As a result of the study of preparations of the lungs, the degree of pulmonary edema was established, as well as the anti-edema effect of pharmacological corrections. On the 6th day of the experiment, the anti-edematous effect was retained only after the introduction of N-acetylcysteine. Histological examination of the lungs showed generalized destruction of the organ architectonics in response to the impact of a damaging factor and its reduction under the influence of pharmacological corrections. In the control group, the signs of acute lung injury were most extensive. One day after the administration of the HyperHAEC solution, there were no hemorrhages in the histological picture of the lungs. In a quantitative assessment of the histological signs of acute lung injury, it was shown that the maximum positive effect from the administration of HyperHAES develops 24 hours after application. N-acetylcysteine primarily led to a decrease in leukocyte infiltration and prevented the development of a suppurative process. The lung-protective effect of N-acetylcysteine was realized in 24 hours from the moment of administration and persisted until the 6th day of the experiment. The use of pharmacological correction agents in acute lung injury was reflected in the picture of the lethality of the experimental animals. When HyperHAES was applied, 37.5% of animals died by day 6, in the group with N-acetylcysteine - 28.6%, while in the control group all animals died.

ADAMTS-13 regulates neutrophil recruitment in a mouse model of invasive pulmonary aspergillosis

Von Willebrand factor (VWF) is secreted as an acute phase protein during inflammation. ADAMTS-13 regulates the size and prothrombotic activity of VWF by it’s specific proteolytic activity. To determine the relevance of this regulatory pathway for the innate inflammatory response by polymorphonuclear neutrophils (PMN), we employed a mouse model of invasive pulmonary aspergillosis (IPA) where PMN functionality is crucial for fungal clearance and survival. IPA was induced by intratracheal application of Aspergillus fumigatus (A. fumigatus) conidia in wildtype (129/Sv/Pas) or ADAMTS-13 deficient (Adamts13−/−) mice. While neutropenic mice developed lethal IPA, all wildtype mice survived the infection. In contrast to wildtype or VWF deficient mice, Adamts13−/− mice displayed more severe signs of disease with a lethal course in 24% with an increased fungal burden and signs of acute lung injury. Histology sections demonstrated a more pronounced perivascular leukocyte infiltration in support of a dysregulated inflammatory response in Adamts13−/− mice. Importantly, we observed no general defect in the activation of neutrophil functions in response to conidia or hyphae in vitro. Therefore, we conclude that the proteolytic regulation of VWF by ADAMTS-13 or ADAMTS-13 by itself is an important mechanism to control PMN recruitment in acute inflammatory processes, such as fungal pneumonias.

Interleukin (IL)-10 Is an Effective Therapeutic for Murine Transfusion Related Acute Lung Injury (TRALI)

Transfusion related acute lung injury (TRALI) is the leading cause of transfusion-induced fatalities and is characterized by acute respiratory distress following blood transfusion. Donor antibodies present in the transfused blood product such as anti-human leukocyte antigen (HLA) or anti-human neutrophil antigen (HNA) antibodies are frequently involved. Currently, there is no treatment available for TRALI apart from supportive measures such as oxygen. The pathogenesis the disorder is incompletely understood, however, several animal models have contributed to our understanding of TRALI disease pathology. Most TRALI reactions are considered to be due to a two-hit paradigm where the first hit is a predisposing patient factor such as inflammation while the second hit is the transfusion. It is widely believed that the second hit delivers antibodies that trigger TRALI in the recipient. The anti-MHC class I antibody, 34-1-2s, has been widely used as an agent that delivers the second TRALI hit in mice. We have previously shown that CD4+ T cells, more specifically, CD4+CD25+FoxP3+ T-regulatory cells (Tregs) convey protection against TRALI (Blood. 126 (23):2342, 2015; abstract #82075, manuscript submitted). In the current study, we utilized a C57BL/6 mouse model of severe TRALI by first depleting mice of CD4+ T cells and then injecting them with the anti-MHC class I monoclonal antibodies (34-1-2s+AF6-88.5.5.3) and we examined the effects of the anti-inflammatory cytokine IL-10 on the antibody-mediated TRALI reaction.IL-10 (45 µg/kg iv) or volume-matched PBS was injected 15 minutes after the administration of anti-MHC antibodies when the onset of TRALI symptoms (e.g. a 2 degree drop in rectal temperature indicative of systemic shock) began. Results show that 90 minutes after anti-MHC class I antibody injection, control mice injected with PBS exhibited a high degree of pulmonary edema as assessed by significantly elevated lung wet-to-dry weight ratios (W/D: 5.84 ± 1.02). Pulmonary neutrophil levels were also found to be increased and lung tissue histology confirmed severe signs of acute lung injury. In contrast, mice injected with IL-10 completely recovered from TRALI; after 90 minutes post-antibody injection they displayed no signs of pulmonary edema (W/D: 4.76 ± 0.04, ** p<0.004 compared to mice injected with PBS) and no signs of severe acute lung injury as assessed by lung tissue histology. Pulmonary neutrophil levels, however, were equally increased in both groups indicating that although IL-10 rescues the mice from acute lung injury, it does not interfere with pulmonary neutrophil recruitment. Preliminary data suggests that IL-10 administration interferes with the ability of neutrophils to generate reactive oxygen species (ROS) that mediate lung injury. Our results suggest that IL-10 therapy significantly rescues an ongoing severe TRALI reaction and this may prove to be an effective and feasible therapeutic strategy in combating human TRALI. DisclosuresNo relevant conflicts of interest to declare.

Neutrophil Recruitment Is Regulated By Adamts-13 in a Murine Model of Invasive Aspergillosis

▪Introduction: During inflammation von Willebrand factor (VWF) multimers are secreted as an acute phase protein whereupon the size and the prothrombotic activity play an essential role. The size of VWF multimers is regulated by the specific proteolytic activity of ADAMTS-13 (a disintegrin and metalloprotease with ThromboSpondin type 1 repeats-13) which is diminished under several pathological conditions. Employing a murine model of invasive pulmonary aspergillosis (IPA) we aimed to determine the relevance of this regulatory pathway for innate inflammatory responses and polymorphonuclear neutrophil (PMN) recruitment which is crucial for fungal clearance and survival.Methods: IPA was induced by intratracheal application of Aspergillus fumigatus (A. fumigatus) conidia in wildtype (129/Sv/Pas) or Adamts13 deficient (Adamts13-/-) mice. 24 h after infection some mice were sacrificed for analysis of fungal load and histology. To assess fungal load as CFU lung homogenates were plated and cultured on Sabourough agar plates. Paraffin sections of the lungs were prepared and stained with mouse complement component C3d antibody for histological analysis. In addition, degranulation, oxidative burst activity and CD62L shedding were assessed in PMN of wildtype and Adamts13-/- mice. Chemotactic properties of A. fumigatus -activated and control serum from wildtype and knock-out mice was evaluated by migration of purified human PMN, isolated by dextran sedimentation and Histopaque® centrifugation, in a transwell assay (Corning® HTS Transwell®-96 well permeable support; 3µm).Results: Adamts13 deficiency in mice was accompanied by a worse outcome of IPA infections compared to wildtype controls. Adamts13-/- mice displayed more severe signs of disease and a lethal course was observed in about 24% of animals. Compared to Adamts13-/- mice all neutropenic mice developed lethal IPA after infection, but all wild-type mice survived the disease. Besides, examination of the lungs revealed a higher fungal burden along with increased signs of acute lung injury, complement deposition and levels of pro-inflammatory cytokines in Adamts13-/- mice. Furthermore a more pronounced perivascular leukocyte infiltration was observed in histological sections indicating a dysregulated inflammatory response in Adamts13-/- mice. Importantly, the activation of neutrophil effector functions in response to TLR agonist or in PMN-mediated fungal killing of conidia or hyphae revealed no general defect in vitro. Despite enhanced complement deposition in the lungs in Adamts13-/- mice, PMN migration towards complement-activated serum revealed unaltered chemotactic properties comparing A. fumigatus -activated serum of wildtype and knock-out mice.Conclusion: In acute inflammatory processes such as fungal pneumonia the proteolytic regulation of VWF by ADAMTS-13 is an important mechanism to control PMN recruitment and outcome of infections. DisclosuresNo relevant conflicts of interest to declare.

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Introduction: The use of airway pressure release ventilation (APRV) has been well characterized in patients with Acute Lung Injury, Acute Respiratory Distress Syndrome, and atelectasis after major surgeries. APRV allows for the minimization of pulmonary barotrauma and facilitates lung-protective inverse-ratio ventilatory strategies in patients with significant injury who may not tolerate inverted ratios in other ventilation modes. We report the successful use of APRV for surgical site protection in a case of membranous tracheal injury requiring surgical repair and postoperative non-ventilatory extracorporeal membrane oxygenation (ECMO) support. A 57 year-old male with a past history significant for esophageal adenocarcinoma s/p robotically assisted esophogectomy presented as a transfer from outside hospital on post operative day 8 after bronchoscopy demonstrated a 7mm perforation in the left main-stem bronchus and multiple punctate perforations of the carina extending into the proximal right main-stem bronchus. A 37-French left double lumen tube was placed to maintain ventilation distal to these defects, and the patient was taken to the operating room for emergent surgical repair and veno-venous ECMO cannulation. Surgical repair was acheived using a combination of autologous pericardial patch and serratus muscle flap, and the patient was admitted to the ICU for management of non-ventilatory ECMO. His lungs were initially managed for 48 hours with a closed 5cm H2O CPAP circuit, with initiation of APRV ventilation on postoperative day 3. Initial CXR demonstrated complete opacification of bilateral lung fields, and initial tidal volumes were 35-50 cc using a P-high of 15 cm H20 and P-low of 5cm H2O. Inverse-ratio ventilation was achieved at 7:1 using a T-high of 5 seconds, and T-low of 0.7 seconds. Peak airway pressures were maintained below 20cm H2O for 48 hours after resumption of ventilation and below 25cm H2O for an additional 48 hours. Mean airway pressures were consistently 10-11cm H2O during the first 48 hours after resumption of ventilation, and peaked at 16cm H2O on postoperative day 6. Respiratory parameters normalized by 96 hours after resumption of ventilation with the patient spontaneously ventilating in excess of 8cc/kg, and ECMO was de-cannulated. Chest radiography on postoperative day 6 demonstrated clear bilateral lung fields, and bronchoscopy demonstrated patent and intact surgical repairs to the membranous trachea. The patient tolerated this ventilatory strategy well, never developed any signs of acute lung injury, and sedation was weaned sufficiently by postoperative day 4 for him to meaningfully interact with his family. The use of inverse-ratio ventilation with APRV in this case provided an ideal management strategy to minimize barotrauma on surgical airway repairs while recruiting previously non-ventilated lungs after ECMO.

Human platelets pathogen reduced with riboflavin and ultraviolet light do not cause acute lung injury in a two‐event SCID mouse model

Pathogen reduction technologies (PRTs) can induce platelet (PLT) lesions that reduce PLT survival and recovery from circulation and may be associated with acute lung injury (ALI). Human PLTs (hPLTs) in plasma with or without single or multiple Mirasol PRT treatments were assessed in vitro by aggregation and percentage of P-selectin expression. In vivo studies included PLT recovery in SCID mice and assessment of ALI in a two-event mouse model in which the sensitizing event was lipopolysaccharide injection and the second event was infusion of Mirasol-treated hPLTs. A single-dose Mirasol treatment (5 J/cm(2) ) did not induce any change in aggregation in response to adenosine 5'-diphosphate (ADP) while a five-times-repeat Mirasol treatment (5×) increased aggregation response to low concentration of ADP. Mirasol PLTs (1×-5×) had increased percentage of P-selectin-positive PLTs after treatment and decreased aggregation with TRAP as the agonist. In vivo recovery in SCID mice was reduced extensively with Mirasol treatments (1× and 5×). In the two-event model of ALI, only the 5× Mirasol PLTs accumulated in the lung and this was not accompanied by changes in lung histology or increases in MIP-2 levels in bronchoalveolar lavage fluid. Mirasol PRT treatment induced PLT activation and reduced in vivo recovery in a SCID mouse model of transfusion. In our two-event mouse model of ALI, the 5× Mirasol hPLTs accumulated in the lung, but did not cause signs of ALI. The 1× Mirasol treatment did not lead to PLT lung accumulation or ALI in this model.

Morphological Signs of Acute Lung Injury of Varying Etiology (Experimental Study)

Objective: to reveal pulmonary morphological changes in acute lung injury (ALI) of varying etiology. Material and methods. An experiment was carried out on 4 groups of albino non-inbred male rats weighing 300—400 g. The following ALI models were 1) acidin-pepsin solution (PH-1.2) aspiration; 2) blood aspiration; 3) blood loss (50% circulating blood volume) concurrent with vascular thrombosis in the microcirculatory bed; 4) artificial ventilation-induced ALI. The duration of the study was 1 hour to 3 days. Histological lung slices were stained with hematoxylin and eosin; a Schiff reaction was conducted. Results. All the animals developed interstitial edema, exhibited desquamation of the bronchial epithelium; damage to the capillary endothelium and basement membranes; segmental leukocyte, macrophage, and lymphocyte infiltration of intraalveolar septa, atelectases, hemorrhages, and sludges. Conclusion. Morphological signs in ALI are nonspecific and they do not depend on an etiological factor. Morphological changes in ALI result in damage to the endothelium of lung capillaries and their basement membranes, higher capillary permeability, extravascular fluid accumulation, and protein exudation with the development of noncardiogenic pulmonary edema. Key words: acute lung injury, blood loss, artificial ventilation, aspiration.

Inhibition of neuronal nitric oxide synthase in ovine model of acute lung injury*

Acute respiratory distress syndrome/acute lung injury is a serious complication of burn patients with concomitant smoke inhalation injury. Nitric oxide has been shown to play a major role in pulmonary dysfunction from thermal damage. In this study, we have tested the hypothesis that inhibition of neuronal nitric oxide synthase could ameliorate the severity of acute lung injury using our well-established ovine model of cutaneous burn and smoke inhalation. Prospective, randomized, controlled, experimental animals study. Investigational intensive care unit at university hospital. Adult female sheep. Female sheep (n = 16) were surgically prepared for the study. Seven days after surgery, all sheep were randomly allocated into three study groups: sham (noninjured, nontreated, n = 6); control (injured, treated with saline, n = 6); and neuronal nitric oxide synthase (injured, treated with specific neuronal nitric oxide synthase inhibitor, ZK 234238 (n = 4). Control and neuronal nitric oxide synthase groups were given a cutaneous burn (40% of total body surface, third degree) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anesthesia. Animals in sham group received fake injury also under halothane anesthesia. After injury or fake injury procedure, all sheep were placed on ventilators and resuscitated with lactated Ringer's solution. Neuronal nitric oxide synthase group was administered with continuous infusion of ZK 234238 started 1 hr postinjury with a dose of 100 microg/kg/hr. Sham and control groups received same amount of saline. Cardiopulmonary hemodynamics monitored during the 24-hr experimental time period was stable in the sham group. Control sheep developed multiple signs of acute lung injury. This pathophysiology included decreased pulmonary gas exchange and lung compliance, increased pulmonary edema, and inflammatory indices, such as interleukin-8. Treatment of injured sheep with neuronal nitric oxide synthase inhibitor attenuated all the observed pulmonary pathophysiology. The results provide definitive evidence that inhibition of neuronal nitric oxide synthase-derived excessive nitric oxide may be a novel and beneficial treatment strategy for pulmonary pathology in burn victims with smoke inhalation injury.

IL-10 deficiency augments acute lung but not liver injury in hemorrhagic shock

In hemorrhagic shock and trauma, patients are prone to develop systemic inflammation with remote organ dysfunction, which is thought to be caused by pro-inflammatory mediators. This study investigates the role of the immuno-modulatory cytokine IL-10 in the development of organ dysfunction following hemorrhagic shock. Male C57/BL6 and IL-10 KO mice were subjected to volume controlled hemorrhagic shock for 3 h followed by resuscitation. Animals were either sacrificed 3 or 24 h after resuscitation. To assess systemic inflammation, serum IL-6, IL-10, KC, and MCP-1 concentrations were measured with the Luminex™ multiplexing platform; acute lung injury (ALI) was assessed by pulmonary myeloperoxidase (MPO) activity and lung histology and acute liver injury was assessed by hepatic MPO activity, hepatic IL-6 levels, and serum ALT levels. There was a trend towards increased IL-6 and KC serum levels 3 h after resuscitation in IL-10 KO as compared to C57/BL6 mice; however this did not reach statistical significance. Serum MCP-1 levels were significantly increased in IL-10 KO mice 3 and 24 h following resuscitation as compared to C57/BL6 mice. In IL-10 KO mice, pulmonary MPO activity was significantly increased 3 h following resuscitation and after 24 h histological signs of acute lung injury were more apparent than in C57/BL6 mice. In contrast, no significant differences in any liver parameters were detected between IL-10 KO and C57/BL6 mice. Our data indicate that an endogenous IL-10 deficiency augments acute lung but not liver injury following hemorrhagic shock.

In Impaired Pulmonary Oxygenizing Function in Cardiosurgical Patients

Objective: to study the impact of administration of surfactant-BL, followed by alveolar mobilization on the parameters of pulmonary oxygenizing function and biomechanics in patients with impaired lung oxygenizing function (ILOF) in the early postoperative period. Subjects and methods. Eight patients aged 48—73 years (mean 59.1±3.0 years) were examined. The indication for alveolar mobilization was an oxygenation index (PaO2/FiO2) of less than 300 mm Hg during artificial ventilation (AV). Alveolar mobilization was carried out under AV, by regulating from the pressure to achieve its airways maximum of 31.6± 1.2 cm H2O and a PEEP of 16.4±0.4 cm H2O. The indication for the use of surfactant-BL (Biosurf, Saint Petersburg) was a reduction of PaO2/FiO2 below 300 mm Hg while attempting to activate the patients. The dose of the agent was 300—450 mg (3.5±0.3 mg/kg) when endobronchially injected. Results. The average increase of PaO2/FiO2 after the first maneuver was 152 mm Hg (p<0.05), that of static thoracopulmonary compliance (Cst) was 12.2 ml/cm H2O (p<0.05); intrapulmonary blood shunting (Qs/Qt) reduced by 5% (p<0.05). On trying to activate the patients, PaO2/FiO2, Cst and Qs/Qt stopped differing from the values recorded before the maneuver. After administering surfactant-BL, followed by alveolar mobilization, there were increases in PaO2/FiO2 (by 177 mm Hg), Cst, and Cdyn (by 15.7 and 14 ml/cm H2O, respectively) (p<0.05). In 7 (87.5%) cases, the trachea was extubated within 6 hours after transferring from the operating suite at a PaO2/FiO2 of 350.9±21.4 mm Hg. Acute respiratory distress syndrome was diagnosed in 1 (12.5%) case. Conclusion. Surfactant-BL substantially enhances the efficiency of the alveolar mobilization maneuver in ILOF early after surgery under extracorporeal circulation. The combined use of the surfactant and the maneuver ensures a stable normalization of the biomechanical properties and oxygenizing function of the lung. There are good grounds to believe that the tested tactics plays a therapeutic and prophylactic role in the early signs of acute lung injury. Key words: impaired lung oxygenizing function, acute lung injury, extracorporeal circulation, pulmonary surfactant system, surfactant-BL, alveolar mobilization, artificial ventilation.

Acute Lung Injury In Pneumonias

The review of the literature considers the etiology and pathogenesis of acute lung injury (ALI) in pneumonias. The development of ALI in pneumonias is largely determined by the properties of microorganisms and by the features of the macroor-ganism. The pathogenic properties of microorganisms lead to a damage to the air-blood barrier and to an impairment of the local protective mechanism in the lung. Alveolar damage, a systemic inflammatory reaction, and extracardiac pulmonary edema provoke ALI in pneumonias. The authors show it difficult to make a differential diagnosis and important to detect the early signs of ALI in pneumonias of various genesis. Transpulmonary thermodilution and identification of the markers of alveolar epithelial damage are promising methods. Key words: acute lung injury, pneumonia, sepsis, cytokines, transpul-monary thermodilution.

Losartan, an angiotensin II receptor blocker, fails to attenuate pulmonary dysfunction in ovine burn and smoke model

Elevated levels of angiotensin II (AngII) in the lung have been shown in response to burn and smoke inhalation injury. AngII has been associated with increased nitric oxide levels, leading to nuclear oxidative damage in Type II lung epithelial cells. Losartan is an AngII receptor blocker, specific to AT1A receptors. Using an ovine model of acute respiratory distress, we hypothesized that blocking AngII receptors with losartan would improve the clinical conditions seen in response to the injury. Chronically prepared adult ewes received a 40% total body surface area third degree flame burn followed by 48 breaths of cotton smoke. The sheep were randomly divided into two groups: control (injury, no treatment, n=6) and treatment (injury + losartan, n= 6). Losartan was given intravenously as a bolus (50 mg) at 1hour post‐injury. All animals received 4ml/kg/%burn of Ringer's lactate and were mechanically ventilated. Control animals showed severe signs of acute lung injury evidenced by deterioration of pulmonary gas exchange (PaO2/FiO2, pulmonary shunt fraction), increased lung water content, and increased pulmonary transvascular fluid flux, and vascular permeability index. Although there was a trend for reduction of lung lymph flow and permeability index, these alterations could not be shown as statistically affected by this dosage of losartan in this 24‐hour ovine model of acute lung injury. SBI 8450, PPG 5P01GM066312

Combined anticoagulants ameliorate acute lung injury in sheep after burn and smoke inhalation

Burn and smoke inhalation-related multiple organ dysfunction is associated with a severe fall in the plasma concentration of antithrombin. Therefore the aim of the present study was to test the hypothesis that intravenous administration of recombinant human antithrombin in combination with aerosolized heparin will ameliorate acute lung injury in sheep exposed to cutaneous burn and smoke inhalation. Sheep were prepared operatively for study and, 7 days post-surgery, sheep were given a cutaneous burn (40% of total body surface area, third-degree burn) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anaesthesia. After injury, sheep were placed on a ventilator and resuscitated with Ringer's lactate solution. The animals were divided into three groups: sham group (non-injured and non-treated; n=6), saline group (injured and received saline; n=6) and rhAT.iv.+Hep group [injured and treated with rhAT (recombinant human antithrombin) and heparin; n=6]. In the rhAT.iv.+Hep group, rhAT was infused continuously for 48 h starting 1 h post-injury with a dose of 0.34 mg.h(-1).kg(-1) of body weight and heparin (10000 units) was aerosolized every 4 h starting at 1 h post-injury. The experiment lasted 48 h. Haemodynamics were stable in sham group, whereas the saline-treated sheep developed multiple signs of acute lung injury, including decreased pulmonary gas exchange, increased inspiratory pressures, extensive airway obstruction and increased pulmonary oedema. These pathological changes were associated with a severe fall in plasma antithrombin concentration, lung tissue accumulation of leucocytes and excessive production of NO. Treatment of injured sheep with anticoagulants attenuated all of the pulmonary pathophysiology observed. In conclusion, the results provide definitive evidence that anticoagulant therapy may be a novel and effective treatment tool in the management of burn patients with concomitant smoke inhalation injury.

Classification of Acute Respiratory Distress Syndrome

The editorial proposes a new classification of acute respiratory distress syndrome (ARDS). Acute lung injury (ALI) is regarded as the first stage of ARDS. Diagnostic tests based on the use of new technologies, such as determination of pulmonary extravascular water, pulmonary capillary permeability index, oxygenation index, and hemodynamic disorders are recommended. The early signs of acute lung injury should be detected to perform early appropriate therapy in order to prevent further complications and to reduce mortality rates.

Aerosolized anticoagulants ameliorate acute lung injury in sheep after exposure to burn and smoke inhalation

Acute lung injury is a detrimental complication for victims of burn accidents. Airway obstruction plays an important role in pulmonary dysfunction in these patients. In this study, we tested the hypothesis that aerosolized anticoagulants will reduce the degree of airway obstruction and improve pulmonary function in sheep with severe combined burn and smoke inhalation injury by preventing the formation of airway fibrin clots. Prospective, randomized, controlled, experimental animal study. Investigational intensive care unit at a university hospital. Adult female sheep. After 7 days of surgical recovery, sheep were given a cutaneous burn (40% of total body surface, third degree) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anesthesia. After injury, sheep were placed on ventilators and resuscitated with lactated Ringer's solution. Sheep were randomly divided into five groups: sham, noninjured and nontreated (n = 6); control, injured and aerosolized with saline (n = 6); recombinant human antithrombin (rhAT) + heparin, injured and aerosolized with rhAT (290 units for each) and heparin (10,000 units for each) (n = 6); rhAT, injured and aerosolized with rhAT alone (290 units for each; n = 5); and heparin, injured and aerosolized with heparin alone (10,000 units for each; n = 5). rhAT and heparin were aerosolized every 4 hrs, starting at 2 hrs postinjury. Cardiopulmonary hemodynamics were monitored during a 48-hr experimental time period. Control sheep developed multiple signs of acute lung injury. This pathophysiology included decreased pulmonary gas exchange and lung compliance, increased pulmonary edema, and extensive airway obstruction. These variables were stable in sham animals. The aerosolization of rhAT or heparin alone did not significantly improve deteriorated pulmonary gas exchange. However, aerosolization of these anticoagulants in combination significantly attenuated all the observed pulmonary pathophysiology. The results provide definitive evidence that aerosolized rhAT and heparin in combination may be a novel treatment strategy for pulmonary pathology in burn victims with smoke inhalation injury.

Intravital microscopy of the murine pulmonary microcirculation

Intravital microscopy (IVM) is considered as the gold standard for in vivo investigations of dynamic microvascular regulation. The availability of transgenic and knockout animals has propelled the development of murine IVM models for various organs, but technical approaches to the pulmonary microcirculation are still scarce. In anesthetized and ventilated BALB/c mice, we established a microscopic access to the surface of the right upper lung lobe by surgical excision of a window of 7- to 10-mm diameter from the right thoracic wall. The window was covered by a transparent polyvinylidene membrane and sealed with alpha-cyanoacrylate. Removal of intrathoracic air via a trans-diaphragmal intrapleural catheter coupled the lung surface to the window membrane. IVM preparations were hemodynamically stable for at least 120 min, with mean arterial blood pressure above 70 mmHg, and mean arterial Po(2) and arterial Pco(2) in the range of 90-100 Torr and 30-40 Torr, respectively. Imaged lungs did not show any signs of acute lung injury or edema. Following infusion of FITC dextran, subpleural pulmonary arterioles and venules of up to 50-microm diameter and alveolar capillary networks could be visualized during successive expiratory plateau phases over a period of at least 2 h. Vasoconstrictive responses to hypoxia (11% O(2)) or infusion of the thromboxane analog U-46619 were prominent in medium-sized arterioles (30- to 50-microm diameter), minor in small arterioles <30 microm, and absent in venules. The presented IVM model may constitute a powerful new tool for investigations of pulmonary microvascular responses in mice.

Pulmonary Circulation in Acute Lung Injury in the Presence of Acute Poisoning by Toxic Substances

Objective: to evaluate the efficiency of therapy in patients with acute intoxication with neurotropic poisons and protracted hypoxia complicated by pneumonia under guidance of impedance study of pulmonary circulation and pulmonary hydration. Subjects and methods. Ninety-six patients with acute intoxication with neurotropic poisons were examined and treated. They were divided into 3 groups: 1) 60 patients without signs of acute lung injury (ALI); 2) 17 with ALI in whom impedance methods for diagnosis and therapy monitoring were used; 3) 19 with ALI who were treated without impedance study. Systemic and pulmonary circulation and pulmonary hydration were evaluated via the one-stage application of integral body rheography (IBR) by the procedure developed by M. I. Tishchenko, thoracic rheography (TRG) after B. B. Sramek, and integral two-frequency impedance study. Results. In patients with ALI, increased thoracic fluid was accompanied by the decreased differential rheogram amplitude, which suggested the diminished pulsating component of blood flow, but the higher amplitude ratio of the differential rheograms obtained at IBR and TRG indicated the presence of impaired regional pulmonary circulation. The patients with ALI, followed by evolving pneumonia had lower differential rheogram amplitudes measured by TRG; they tended to have higher thoracic fluid levels and lower ejection rates. Conclusion. In patients with acute severe intoxication with neurotropic poisons, the risk for ALI is determined by the severity of intoxication and the duration and depth of hypoxia. The development of a critical condition determines the degree of pulmonary hyperhydration that depends on the pattern of cardiovascular abnormalities (a fall of single cardiac performance and pulmonary microcirculato-ry disorders). Monitoring of blood circulatory and microcirculatory disorders determines the basic treatment options and outcome. Key words: acute intoxication with neurotropic poisons, acute lung injury, pneumonia, integral body rheography, thoracic rheography, integral two-frequency impedance study.

Activation of the STAT pathway in acute lung injury.

Acute lung injury (ALI) is a devastating clinical problem with a mortality as high as 60%. It is now appreciated that ALI represents a cytokine excess state that involves the microvasculature of multiple organs. The signal transducers and activators of transcription (STAT) family of transcription factors activate critical mediators of cytokine responses, but there is limited knowledge about their role in mediating ALI. In the present study, we demonstrate that the STAT transcription factors are activated rapidly in the lungs after intraperitoneal and intranasal LPS administration in mice. We also demonstrated that LPS activates both the STAT kinases, Src and JAK, in the lung with kinetics that are consistent with STAT activation. LPS treatment resulted in STAT3 activation throughout the resident lung cells, as well as in the recruited inflammatory cells. Whereas direct LPS treatment did not lead to STAT activation in cultured epithelial or endothelial cells, IL-6 activated STAT3 in both of these cell types. Furthermore, IL-6 was induced by LPS in serum and in the lung with kinetics consistent with STAT3 activation, suggesting that IL-6 may be one mechanism of STAT activation by LPS. In addition, STAT activation required reactive oxygen species, as the overexpression of catalase in mice prevented LPS-mediated STAT activation in the lung. STATs may be a common pathway for mediating ALI, regardless of the inciting factor, as STAT activation also occurred in both a gastric acid aspiration and acute pancreatitis model of ALI. Finally, STATs are activated in the lung long before signs of ALI are present, suggesting that the STAT transcription factors may play a role in initiating the inflammatory response seen in the lung.

High-frequency oscillatory ventilation and partial liquid ventilation after acute lung injury in premature lambs with respiratory distress syndrome.

Conventional mechanical ventilatory support (CV) contributes to lung injury in premature lambs with respiratory distress syndrome, a disease that is characterized by progressive deterioration of gas exchange and increased lung inflammation. Lung recruitment strategies, such as high-frequency oscillatory ventilation (HFOV) and partial liquid ventilation (PLV), improve gas exchange and attenuate lung inflammation when instituted immediately after birth. However, whether these recruitment strategies are effective as rescue treatment after established lung injury is unknown. To determine the separate and combined effects of HFOV and PLV when initiated after the establishment of acute lung injury in severe respiratory distress syndrome, we studied the effects of these strategies on gas exchange and histologic signs of acute lung injury in premature lambs. Animals were intubated, treated with surfactant and ventilated with 1.00 FIO2 for 4 hrs. After 2 hrs, animals were either continued on CV (controls) or treated with one of three strategies: HFOV; CV + PLV; or HFOV + PLV. The response to low-dose inhaled nitric oxide (5 ppm) was measured in each group at the end of the study. An animal laboratory affiliated with University of Colorado School of Medicine. A total of 20 premature lambs at 115-118 days of gestation (term = 147 days). In comparison with control animals, each of the rescue therapies improved PaO2 after 1 hr of treatment. The HFOV and HFOV + PLV groups had higher PaO2 than CV + PLV or CV alone (p < .05). Mean airway pressure (Paw) was lower in the PLV groups during CV or HFOV compared with their controls (p < .05). Inhaled NO improved PaO2 in all groups; however, the increase in PaO2 was greatest in the HFOV + PLV group (p < .05). Histologic examination and myeloperoxidase assay were not different between groups. We conclude that each lung recruitment strategy improved oxygenation in premature lambs with established lung injury.