• Am. J. Respir. Crit. Care Med. · Feb 2016

    Acute Lung Injury Causes Asynchronous Alveolar Ventilation Which Can Be Corrected by Individual Sighs.

    • Arata Tabuchi, Hannah T Nickles, Michael Kim, John W Semple, Edmund Koch, Laurent Brochard, Arthur S Slutsky, Axel R Pries, and Wolfgang M Kuebler.
    • 1 Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.
    • Am. J. Respir. Crit. Care Med. 2016 Feb 15; 193 (4): 396-406.

    RationaleImproved ventilation strategies have been the mainstay for reducing mortality in acute respiratory distress syndrome. Their unique clinical effectiveness is, however, unmatched by our understanding of the underlying mechanobiology, and their impact on alveolar dynamics and gas exchange remains largely speculative.ObjectivesTo assess changes in alveolar dynamics and associated effects on local gas exchange in experimental models of acute lung injury (ALI) and their responsiveness to sighs.MethodsAlveolar dynamics and local gas exchange were studied in vivo by darkfield microscopy and multispectral oximetry in experimental murine models of ALI induced by hydrochloric acid, Tween instillation, or in antibody-mediated transfusion-related ALI.Measurements And Main ResultsIndependent of injury mode, ALI resulted in asynchronous alveolar ventilation characteristic of alveolar pendelluft, which either spontaneously resolved or progressed to a complete cessation or even inversion of alveolar ventilation. The functional relevance of the latter phenomena was evident as impaired blood oxygenation in juxtaposed lung capillaries. Individual sighs (2 × 10 s at inspiratory plateau pressure of 30 cm H2O) largely restored normal alveolar dynamics and gas exchange in acid-induced ALI, yet not in Tween-induced surfactant depletion.ConclusionsWe describe for the first time in detail the different forms and temporal sequence of impaired alveolar dynamics in the acutely injured lung and report the first direct visualization of alveolar pendelluft. Moreover, we identify individual sighs as an effective strategy to restore intact alveolar ventilation by a mechanism independent of alveolar collapse and reopening.

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