Objective: Positive end-expiratory pressure exerts its effects keeping open at end-expiration previously collapsed areas of the lung; consequently, higher positive end-expiratory pressure should be limited to patients with high recruitability. We aimed to determine which bedside method would provide positive end-expiratory pressure better related to lung recruitability.
Design: Prospective study performed between 2008 and 2011.
Setting: Two university hospitals (Italy and Germany).
Patients: Fifty-one patients with acute respiratory distress syndrome.
Interventions: Whole lung CT scans were taken in static conditions at 5 and 45 cm H2O during an end-expiratory/end-inspiratory pause to measure lung recruitability. To select individual positive end-expiratory pressure, we applied bedside methods based on lung mechanics (ExPress, stress index), esophageal pressure, and oxygenation (higher positive end-expiratory pressure table of lung open ventilation study).
Measurements and Main Results: Patients were classified in mild, moderate and severe acute respiratory distress syndrome. Positive end-expiratory pressure levels selected by the ExPress, stress index, and absolute esophageal pressures methods were unrelated with lung recruitability, whereas positive end-expiratory pressure levels selected by the lung open ventilation method showed a weak relationship with lung recruitability (r2 = 0.29; p < 0.0001). When patients were classified according to the acute respiratory distress syndrome Berlin definition, the lung open ventilation method was the only one which gave lower positive end-expiratory pressure levels in mild and moderate acute respiratory distress syndrome compared with severe acute respiratory distress syndrome (8 ± 2 and 11 ± 3 cm H2O vs 15 ± 3 cm H2O; p < 0.05), whereas ExPress, stress index, and esophageal pressure methods gave similar positive end-expiratory pressure values in mild, moderate, and severe acute respiratory distress syndrome. The positive end-expiratory pressure selected by the different methods were unrelated to each other with the exception of the two methods based on lung mechanics (ExPress and stress index).
Conclusions: Bedside positive end-expiratory pressure selection methods based on lung mechanics or absolute esophageal pressures provide positive end-expiratory pressure levels unrelated to lung recruitability and similar in mild, moderate, and severe acute respiratory distress syndrome, whereas the oxygenation-based method provided positive end-expiratory pressure levels related with lung recruitability progressively increasing from mild to moderate and severe acute respiratory distress syndrome.
1Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca’ Granda–Ospedale Maggiore Policlinico, Milan, Italy.
2Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy.
3Dipartimento di Radiologia, Fondazione IRCCS Ca’ Granda–Ospedale Maggiore Policlinico, Milan, Italy.
4Department of Anaesthesiology, Emergency and Intensive Care Medicine, Georg-August University of Göttingen, Göttingen, Germany.
* See also p. 448.
http://www.clinicaltrial.gov number: NCT00682942.
Gattinoni, Chiumello, Moerer, and Quintel contributed to conception and design. Caspani, Chiumello, Marino, Gallazzi, Lazzerini, Moerer, and Quintel contributed to acquisition of data. Gattinoni, Cressoni, Carlesso, Caspani, Marino, Gallazzi, Lazzerini, and Caironi contributed to analysis and interpretation of data. Gattinoni, Cressoni, Carlesso, and Chiumello contributed to drafting of the article. Caironi, Caspani, Marino, Gallazzi, Lazzerini, Moerer, and Quintel contributed to critical revision of the article for important intellectual content. Cressoni and Carlesso contributed to statistical analysis.
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Supported, in part, by institutional funding.
Dr. Gattinoni received an Italian grant (PR-0062) from Fondazione Fiera di Milano for Translational and Competitive Research (2007). The remaining authors have disclosed that they do not have any potential conflicts of interest.
Address requests for reprints to: Luciano Gattinoni, MD, FRCP, Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca’ Granda–Ospedale Maggiore Policlinico, via Francesco Sforza 35, 20122 Milan, Italy. E-mail: email@example.com