• João Batista Borges, Eduardo L V Costa, Maria Bergquist, Luca Lucchetta, Charles Widström, Enn Maripuu, Fernando Suarez-Sipmann, Anders Larsson, Marcelo B P Amato, and Göran Hedenstierna.
• 1Hedenstierna Laboratory, Department of Surgical Sciences, Section of Anaesthesiology & Critical Care, Uppsala University, Uppsala, Sweden. 2Pulmonary Division, Cardio-Pulmonary Department, Heart Institute (Incor), University of São Paulo, São Paulo, Brazil. 3Research and Education Institute, Hospital Sirio-Libanês, São Paulo, Brazil. 4Hedenstierna Laboratory, Department of Medical Sciences, Clinical Physiology, Uppsala University, Uppsala, Sweden. 5Intensive Care Department, Hospital San Matteo, Pavia, Italy. 6Department of Medical Physics, University Hospital, Uppsala, Sweden. 7Centros de Investigación Biomédica en Red de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
• Crit. Care Med.. 2015 May 1;43(5):e123-32.

ObjectivePET with [18F]fluoro-2-deoxy-D-glucose can be used to image cellular metabolism, which during lung inflammation mainly reflects neutrophil activity, allowing the study of regional lung inflammation in vivo. We aimed at studying the location and evolution of inflammation by PET imaging, relating it to morphology (CT), during the first 27 hours of application of protective-ventilation strategy as suggested by the Acute Respiratory Distress Syndrome Network, in a porcine experimental model of acute respiratory distress syndrome.DesignProspective laboratory investigation.SettingUniversity animal research laboratory.SubjectsTen piglets submitted to an experimental model of acute respiratory distress syndrome.InterventionsLung injury was induced by lung lavages and 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressure and high inspiratory pressures. During 27 hours of controlled mechanical ventilation according to Acute Respiratory Distress Syndrome Network strategy, the animals were studied with dynamic PET imaging of [18F]fluoro-2-deoxy-D-glucose at two occasions with 24-hour interval between them.Measurements And Main Results[18F]fluoro-2-deoxy-D-glucose uptake rate was computed for the total lung, four horizontal regions from top to bottom (nondependent to dependent regions) and for voxels grouped by similar density using standard Hounsfield units classification. The global lung uptake was elevated at 3 and 27 hours, suggesting persisting inflammation. In both PET acquisitions, nondependent regions presented the highest uptake (p = 0.002 and p = 0.006). Furthermore, from 3 to 27 hours, there was a change in the distribution of regional uptake (p = 0.003), with more pronounced concentration of inflammation in nondependent regions. Additionally, the poorly aerated tissue presented the largest uptake concentration after 27 hours.ConclusionsProtective Acute Respiratory Distress Syndrome Network strategy did not attenuate global pulmonary inflammation during the first 27 hours after severe lung insult. The strategy led to a concentration of inflammatory activity in the upper lung regions and in the poorly aerated lung regions. The present findings suggest that the poorly aerated lung tissue is an important target of the perpetuation of the inflammatory process occurring during ventilation according to the Acute Respiratory Distress Syndrome Network strategy.

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