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Lung Mechanics (lung + mechanic)
Selected AbstractsRegional pulmonary pressure volume curves in mechanically ventilated patients with acute respiratory failure measured by electrical impedance tomographyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2006J. Hinz Background:, We hypothized, that in mechanically ventilated patients with acute respiratory failure, regional pressure volume curves differ markedly from conventional global pressure volume curves of the whole lung. Methods:, In nine mechanically ventilated patients with acute respiratory failure during an inspiratory low-flow manoeuvre, conventional global pressure volume curves were registered by spirometry and regional pressure volume curves in up to 912 regions were assessed simultaneously using electrical impedance tomography. We compared the lower (LIP) and upper (UIP) inflection points obtained from the conventional global pressure volume curve and regional pressure volume curves. Results:, We identified from the conventional global pressure volume curves LIP [3,11 (8) cmH2O] in eight patients and UIP [31,39 (33) cmH2O] in three patients. Using electrical impedance tomography (EIT), LIP [3,18 (8) cmH2O] in 54,264 (180) regions and UIP [23,42 (36) cmH2O] in 149,324 (193) regions (range and median) were identified. Lung mechanics measured by conventional global pressure volume curves are similar to the median of regional pressure volume curves obtained by EIT within the tomographic plane. However, single regional pressure volume curves differ markedly with a broad heterogeneity of lower and upper inflection points. Conclusion:, Lower and upper inflection points obtained from conventional global pressure volume curves are not representative of all regions of the lungs. [source] The effects of methylene blue on ovine post-pneumonectomy pulmonary oedemaACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2010E. V. SUBOROV Background: We recently reported that post-pneumonectomy pulmonary oedema (PPO) occurs after ventilating the remaining lung with excessive tidal volumes. Studies in small animals have indicated that nitric oxide (NO) release increases in hyper-inflated lungs, but confirmatory evidence from larger animals is still lacking. We hypothesized that PPO could be prevented by methylene blue (MB), an inhibitor of NO synthase. Methods: Sheep were subjected to a right-sided pneumonectomy (PE) and randomly assigned to a protectively ventilated group ((PROTV group, n=7) with tidal volumes of 6 ml/kg at 20 inflations/min and a positive end-expiratory pressure (PEEP) of 2 cmH2O, and two groups undergoing ,injurious ventilation' (INJV) with tidal volumes of 12 ml/kg and zero end-expiratory pressure (ZEEP), a control group (INJV group, n=7) and a treatment group subjected to MB 1 h after PE (INJV+MB group, n=7). Haemodynamic variables, lung mechanics, blood gases and plasma nitrites and nitrates (NOx) were determined. Results: PE reduced pulmonary blood volume, extravascular lung water (EVLWI) and quasistatic lung compliance in all groups, in parallel with a rise in peak airway pressure (P<0.05). In the INJV group, pulmonary arterial pressure, EVLWI and pulmonary vascular permeability index increased and arterial oxygenation decreased towards cessation of the experiments. These changes were not antagonized by MB. Plasma NOx increased in all the groups compared with baseline, but with no intergroup difference. Conclusion: MB did not reduce PPO and accumulation of NOx in sheep subjected to ventilation with excessive tidal volumes and ZEEP. [source] Pneumomediastinum simulating a panic attack in a patient with anorexia nervosaINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 1 2003Anita Karim Abstract Objective Pneumomediastinum is a rare complication of anorexia nervosa. Although the mechanism is unknown, severe malnutrition may affect lung mechanics by altering the connective tissue, predisposing to pneumomediastinum. Method We describe a young male with anorexia nervosa and panic disorder who presented with symptoms similar to those of a panic attack and was diagnosed with spontaneous pneumomediastinum. Results This case illustrates the importance of considering pneumomediastinum in the differential diagnosis of panic attack in patients with eating disorders. Discussion Although spontaneous pneumomediastinum has a generally benign course, it must be differentiated from the potentially life-threatening secondary pneumomediastinum due to an esophageal tear. © 2002 by Wiley Periodicals, Inc. Int J Eat Disord 33: 104,107, 2003. [source] Lack of Clinical Efficacy of a Phosphodiesterase-4 Inhibitor for Treatment of Heaves in HorsesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2006Jean-Pierre Lavoie Phosphodiesterase-4 (PDE 4) enzyme inhibitors have been shown to have anti-inflammatory properties in various animal disease processes and therefore could be effective drugs for the treatment of equine airway diseases. The purpose of this study was to evaluate the efficacy and adverse effects of the PDE 4 inhibitor L-826,141 in horses with heaves. In a blinded parallel design, horses with heaves exposed daily to moldy hay were given a placebo for 14 days and then administered either L-826,141 (n = 6; loading dose of 1 mg/kg IV followed by 0.5 mg/kg IV q48h) or dexamethasone (n = 6; 0.04 mg/kg IV q24h) from days 15 to 29 (study 1). Pulmonary function and bronchoalveolar (BAL) cytology were evaluated weekly from baseline (day 0) to 29 days. In study 2, horses were treated with L-826,141 (1.0 mg/kg IV q24h) for 8 days. Although ex vivo lipopolysaccharide-induced tumor necrosis factor (TNF)-, and LTB4 production by fresh blood were inhibited up to 90% after repeated administrations of L-826,141, this treatment failed to improve lung function. In contrast, dexamethasone (positive control) treatment resulted in significant improvement in lung mechanics and airway function in all horses. Neither drug had a significant effect on BAL total cell counts and differential cytology. Administration of the PDE 4 inhibitor L-826,141 for up to 14 days to horses with heaves was not associated with an improvement in airway function or inflammation. These findings suggest that the PDE 4 enzyme is not a key mediator of lung inflammation in heaves. [source] Natural surfactant combined with beclomethasone decreases oxidative lung injury in the preterm lambPEDIATRIC PULMONOLOGY, Issue 12 2009Carlo Dani MD Abstract We performed a randomized study in preterm lambs to assess the hypothesis that the treatment with natural surfactant combined with beclomethasone might decrease pulmonary oxidative stress in an animal model of respiratory distress syndrome (RDS). Animals received 200,mg/kg of porcine natural surfactant or 200,mg/kg of natural surfactant combined with 400 or 800,µg/kg of beclomethasone. Lung tissue oxidation was studied by measuring total hydroperoxide (TH), advanced oxidation protein products (AOPP), and non-protein bound iron (NPBI) in bronchial aspirate samples. In addition, lung mechanics was evaluated. TH was lower in the groups treated with surfactant plus 400 or 800,µg/kg of beclomethasone than in the surfactant group; AOPP was lower in the group treated with surfactant plus 800,µg/kg of beclomethasone than in the other groups; NPBI was similar in all groups. Surfactant treatment was followed by a sustained improvement of tidal volume (TV) and airway resistance, while dynamic compliance did not vary. However, the mean airway pressure needed to obtain similar values of TV was lower in the group treated with surfactant plus 800,µg/kg of beclomethasone than in other groups. We concluded that natural surfactant combined with beclomethasone at 800,µg/kg is effective in reducing the oxidative lung stress and improving the respiratory function in an animal model of RDS. Pediatr Pulmonol. 2009; 44:1159,1167. © 2009 Wiley-Liss, Inc. [source] The effect of fetal tracheal occlusion on lung tissue mechanics and tissue composition,PEDIATRIC PULMONOLOGY, Issue 2 2009Jacques C. Jani MD Abstract Fetal tracheal occlusion (TO) is currently used to treat severe cases of congenital diaphragmatic hernia (DH). Clinical and experimental studies suggest an improved postnatal outcome, but lung tissue mechanics after TO have not been studied. We determined the effect of TO on mechanical impedance and lung tissue components in a rabbit model for DH. At 23 days of gestation (term,=,31 days) either a sham thoracotomy or a diaphragmatic defect was induced. DH fetuses were randomly assigned to undergo 5 days later TO. Fetuses were delivered by term cesarean section to determine lung to body weight ratio (LBWR), dynamic lung mechanics and lung impedance. Airway resistance (Raw), elastance (HL), tissue damping (GL) and hysteresivity (GL/HL) were calculated from impedance data. Collagen I and III and elastin were quantified histologically. LBWR was significantly increased by TO compared to DH (P,<,0.001) and resistance and compliance of the respiratory system (Rrs, Crs) were improved as well. TO resulted in a significant decrease of Raw comparable to observations in sham-fetuses, without effect on lung tissue mechanics HL, GL and hysteresivity. This coincides with a significant decrease of collagen I, III and elastin in comparison to DH fetuses. In this first report on lung tissue mechanics in a rabbit model of DH, TO had a substantial effect on tissue morphology yet this was not mirrored in lung mechanics. We conclude that the effect of TO on lung mechanics without in utero reversal of occlusion, is dominated by airway remodeling. Pediatr Pulmonol. 2009; 44:112,121. © 2009 Wiley-Liss, Inc. [source] Improved lung function after thoracocentesis in patients with paradoxical movement of a hemidiaphragm secondary to a large pleural effusionRESPIROLOGY, Issue 5 2007Lee-Min WANG Background and objectives: Previous studies have shown little or no improvement in pulmonary function and arterial blood oxygenation after therapeutic thoracocentesis. This study investigated changes in pulmonary function, arterial blood gases and dyspnoea after therapeutic thoracocentesis in patients with paradoxical movement (PM) of a hemidiaphragm due to pleural effusion. Methods: Twenty-one patients with pleural effusion and PM of a hemidiaphragm and 41 patients with pleural effusion but without paradoxical movement (NPM) were studied before and 24 h after thoracocentesis. Lung function measurements included lung mechanics, blood gas exchange and the Borg dyspnoea scale. Results: At thoracocentesis a mean of 1220 mL of pleural fluid was removed from the PM group and 1110 mL from the NPM group. Post-thoracocentesis the PM group showed small but significant improvement (P < 0.05) in FEV1 (63% vs 73%), FVC (67% vs 77%), PaO2 (66 mm Hg vs 73 mm Hg), A-a O2 gradient (38 mm Hg vs 30 mm Hg), and the Borg scale (5.1 vs 2.1). The NPM group showed no significant change in any parameter. Conclusions: Statistically significant improvement in pulmonary function following thoracocentesis was observed in patients with pleural effusion and PM of the hemidiaphragm. Patient selection may therefore explain the different outcomes of thoracocentesis reported in previous studies. [source] | ||||||||||