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Sökning: WFRF:(Jonson Björn) > (2005-2009) > Brochard Laurent > Jonson Björn

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  • Demoule, Alexandre, et al. (författare)
  • Relationship between pressure-volume curve and markers for collagen turn-over in early acute respiratory distress syndrome
  • 2006
  • Ingår i: Intensive Care Medicine. - Springer. - 0342-4642 .- 1432-1238. ; 32:3, s. 413-420
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: In acute respiratory distress syndrome, the relationships between changes in the elastic behavior of the respiratory system and biological markers of extra-cellular matrix or surfactant turn-over could give some insights into its pathophysiological determinants. DESIGN AND MEASUREMENTS: In 17 patients with acute respiratory distress syndrome, we assessed the relationship between chord compliance measured on pressure-volume curves obtained at two levels of positive end-expiratory pressure (0 and 10[Symbol: see text]cm[Symbol: see text]H(2)O) and biological markers of collagen turn-over or surfactant degradation in bronchoalveolar lavage fluid obtained simultaneously in the early phase of the disease (first 4 days). MAIN RESULTS: The compliance of the respiratory system obtained from the pressure-volume curves was significantly correlated with markers for collagen turn-over (type III procollagen peptide and matrix metalloproteinase 2) and with markers of surfactant degradation (type-IIA secretory phospholipase A2). The correlations were stronger when the curve was traced from positive end-expiratory pressure, suggesting that this condition may improve the assessment of tissue mechanics. A logarithmic relationship best described the correlation between compliance and type III procollagen peptide, in agreement with a collagen-dependent model of maximal distension. The marker for surfactant degradation was associated with ongoing alveolar inflammation (cellularity of bronchoalveolar lavage fluid and tumor necrosis factor-alpha concentration). Interleukin-10, an anti-inflammatory mediator, showed no correlation with compliance. CONCLUSION: These preliminary data suggest that a severe reduction in compliance in the early phase of acute respiratory distress syndrome is associated with both collagen deposition and surfactant degradation.
  • Devaquet, Jerome, et al. (författare)
  • Effects of inspiratory pause on CO2 elimination and arterial PCO2 in acute lung injury
  • 2008
  • Ingår i: Journal of Applied Physiology. - American Physiological Society. - 8750-7587 .- 1522-1601. ; 105:6, s. 1944-1949
  • Tidskriftsartikel (refereegranskat)abstract
    • A high respiratory rate associated with the use of small tidal volumes, recommended for acute lung injury (ALI), shortens time for gas diffusion in the alveoli. This may decrease CO2 elimination. We hypothesized that a postinspiratory pause could enhance CO2 elimination and reduce PaCO2 by reducing dead space in ALI. In 15 mechanically ventilated patients with ALI and hypercapnia, a 20% postinspiratory pause (Tp20) was applied during a period of 30 min between two ventilation periods without postinspiratory pause (Tp0). Other parameters were kept unchanged. The single breath test for CO2 was recorded every 5 min to measure tidal CO2 elimination (VtCO(2)), airway dead space (V-Daw), and slope of the alveolar plateau. PaO2, PaCO2, and physiological and alveolar dead space (V-Dphys, V-Dalv) were determined at the end of each 30-min period. The postinspiratory pause, 0.7 +/- 0.2 s, induced on average < 0.5 cmH(2)O of intrinsic positive end-expiratory pressure (PEEP). During Tp20, VtCO(2) increased immediately by 28 +/- 10% (14 +/- 5 ml per breath compared with 11 +/- 4 for Tp0) and then decreased without reaching the initial value within 30 min. The addition of a postinspiratory pause significantly decreased V-Daw by 14% and V-Dphys by 11% with no change in V-Dalv. During Tp20, the slope of the alveolar plateau initially fell to 65 +/- 10% of baseline value and continued to decrease. Tp20 induced a 10 +/- 3% decrease in PaCO2 at 30 min (from 55 +/- 10 to 49 +/- 9 mmHg, P < 0.001) with no significant variation in PaO2. Postinspiratory pause has a significant influence on CO2 elimination when small tidal volumes are used during mechanical ventilation for ALI.
  • Richard, Jean-Christophe M., et al. (författare)
  • Effects of vertical positioning on gas exchange and lung volumes in acute respiratory distress syndrome
  • 2006
  • Ingår i: Intensive Care Medicine. - Springer. - 1432-1238 .- 0342-4642. ; 32:10, s. 1623-1626
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Supine position may contribute to the loss of aerated lung volume in patients with acute respiratory distress syndrome (ARDS). We hypothesized that verticalization increases lung volume and improves gas exchange by reducing the pressure surrounding lung bases. Design and setting: Prospective observational physiological study in a medical ICU. Subjects and intervention: In 16 patients with ARDS we measured arterial blood gases, pressure-volume curves of the respiratory system recorded from positive-end expiratory pressure (PEEP), and changes in lung volume in supine and vertical positions (trunk elevated at 45 degrees and legs down at 45 degrees). Measurements and results: Vertical positioning increased PaO2 significantly from 94 +/- 33 to 142 +/- 49 mmHg, with an increase higher than 40% in 11 responders. The volume at 20 cmH(2)O measured on the PV curve from PEEP increased using the vertical position only in responders (233 +/- 146 vs. -8 +/- 91 ml in nonresponders); this change was correlated to oxygenation change (p = 0.55). End-expiratory lung volume variation from supine to vertical and 1 h later back to supine, measured in 12 patients showed a significant increase during the 1-h upright period in responders (n =7) but not in nonresponders (n = 5; 215 +/- 220 vs. 10 +/- 22 ml), suggesting a time-dependent recruitment. Conclusions: Vertical positioning is a simple technique that may improve oxygenation and lung recruitment in ARDS patients.
  • Åström, Elisabet, et al. (författare)
  • Pattern of inspiratory gas delivery affects CO(2) elimination in health and after acute lung injury.
  • 2008
  • Ingår i: Intensive Care Medicine. - Springer. - 0342-4642 .- 1432-1238. ; 34:2, s. 377-384
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective To avoid ventilator induced lung injury, tidal volume should be low in acute lung injury (ALI). Reducing dead space may be useful, for example by using a pattern of inspiration that prolongs the time available for gas distribution and diffusion within the respiratory zone, the mean distribution time (MDT). A study was conducted to investigate how MDT affects CO2 elimination in pigs at health and after ALI.<br /> Design and setting Randomised crossover study in the animal laboratory of Lund University Biomedical Center.<br /> Subjects and intervention Healthy pigs and pigs with ALI, caused by surfactant perturbation and lung-damaging ventilation were ventilated with a computer-controlled ventilator. With this device each breath could be tailored with respect to insufflation time and pause time (T I and T P) as well as flow shape (square, increasing or decreasing flow).<br /> Measurements and results The single-breath test for CO2 allowed analysis of the volume of expired CO2 and the volume of CO2 re-inspired from Y-piece and tubes. With a long MDT caused by long T I or T P, the expired volume of CO2 increased markedly in accordance with the MDT concept in both healthy and ALI pigs. High initial inspiratory flow caused by a short T I or decreasing flow increased the re-inspired volume of CO2. Arterial CO2 increased during a longer period of short MDT and decreased again when MDT was prolonged.<br /> Conclusions CO2 elimination can be enhanced by a pattern of ventilation that prolongs MDT. Positive effects of prolonged MDT caused by short T I and decreasing flow were attenuated by high initial inspiratory flow.<br /> Electronic supplementary material The online version of this article (doi:10.1007/s00134-007-0840-7) contains supplementary material, which is available to authorized users.
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