Early inflammation mainly affects normally and poorly aerated lung in experimental ventilator-induced lung injury*.
OBJECTIVE
The common denominator in most forms of ventilator-induced lung injury is an intense inflammatory response mediated by neutrophils. PET with [(18)F]fluoro-2-deoxy-D-glucose can be used to image cellular metabolism, which, during lung inflammatory processes, mainly reflects neutrophil activity, allowing the study of regional lung inflammation in vivo. The aim of this study was to assess the location and magnitude of lung inflammation using PET imaging of [(18)F]fluoro-2-deoxy-D-glucose in a porcine experimental model of early acute respiratory distress syndrome.


METHODS
Prospective laboratory investigation.


METHODS
A university animal research laboratory.


METHODS
Seven piglets submitted to experimental ventilator-induced lung injury and five healthy controls.


METHODS
Lung injury was induced by lung lavages and 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressure and high inspiratory pressures. All animals were subsequently studied with dynamic PET imaging of [(18)F]fluoro-2-deoxy-D-glucose. CT scans were acquired at end expiration and end inspiration.


RESULTS
[(18)F]fluoro-2-deoxy-D-glucose uptake rate was computed for the whole lung, four isogravitational regions, and regions grouping voxels with similar density. Global and intermediate gravitational zones [(18)F]fluoro-2-deoxy-D-glucose uptakes were higher in ventilator-induced lung injury piglets compared with controls animals. Uptake of normally and poorly aerated regions was also higher in ventilator-induced lung injury piglets compared with control piglets, whereas regions suffering tidal recruitment or tidal hyperinflation had [(18)F]fluoro-2-deoxy-D-glucose uptakes similar to controls.


CONCLUSIONS
The present findings suggest that normally and poorly aerated regions--corresponding to intermediate gravitational zones--are the primary targets of the inflammatory process accompanying early experimental ventilator-induced lung injury. This may be attributed to the small volume of the aerated lung, which receives most of ventilation.
1Hedenstierna Laboratory, Department of Surgical Sciences, Section of Anaesthesiology & Critical Care, Uppsala University, Uppsala, Sweden. 2Pulmonary Divison, Heart Institute (Incor) Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. 3Research and Education Institute, Hospital Sírio Libanês, São Paulo, Brazil. 4Centros de Investigación Biomédica en Red de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain. 5Department of Hospital Physics, Uppsala University Hospital, Uppsala, Sweden. 6Hedenstierna Laboratory, Department of Medical Sciences, Clinical Physiology, Uppsala University, Uppsala, Sweden.
João Batista
JB
Borges
Eduardo L V
EL
Costa
Fernando
F
Suarez-Sipmann
Charles
C
Widström
Anders
A
Larsson
Marcelo
M
Amato
Göran
G
Hedenstierna
D000818:Animals; D001784:Blood Gas Analysis; D019788:Fluorodeoxyglucose F18; D006403:Hematologic Tests; D006439:Hemodynamics; D007249:Inflammation / Q000276:immunology; D008168:Lung / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D049268:Positron-Emission Tomography; D011659:Pulmonary Gas Exchange; D019275:Radiopharmaceuticals; D013552:Swine; D055397:Ventilator-Induced Lung Injury / Q000276:immunology*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18