• Aydra Mendes Almeida Bianchi, Maycon Moura Reboredo, Leda Marília Fonseca Lucinda, Fernando Fonseca Reis, Manfrinni Vinícius Alves Silva, Maria Aparecida Esteves Rabelo, Marcelo Alcantara Holanda, Júlio César Abreu Oliveira, José Ángel Lorente, and Bruno do Valle Pinheiro.
• Pulmonary Research Laboratory, Hospital Universitário da Universidade Federal de Juiz de Fora, Av. Eugênio do Nascimento - s/nº, Dom Bosco, Juiz de Fora, MG, 36038-330, Brazil.
• Lung. 2016 Apr 1; 194 (2): 193-9.

IntroductionThe benefits of prone position ventilation are well demonstrated in the severe forms of acute respiratory distress syndrome, but not in the milder forms. We investigated the effects of prone position on arterial blood gases, lung inflammation, and histology in an experimental mild acute lung injury (ALI) model.MethodsALI was induced in Wistar rats by intraperitoneal Escherichia coli lipopolysaccharide (LPS, 5 mg/kg). After 24 h, the animals with PaO2/FIO2 between 200 and 300 mmHg were randomized into 2 groups: prone position (n = 6) and supine position (n = 6). Both groups were compared with a control group (n = 5) that was ventilated in the supine position. All of the groups were ventilated for 1 h with volume-controlled ventilation mode (tidal volume = 6 ml/kg, respiratory rate = 80 breaths/min, positive end-expiratory pressure = 5 cmH2O, inspired oxygen fraction = 1) RESULTS: Significantly higher lung injury scores were observed in the LPS-supine group compared to the LPS-prone and control groups (0.32 ± 0.03; 0.17 ± 0.03 and 0.13 ± 0.04, respectively) (p < 0.001), mainly due to a higher neutrophil infiltration level in the interstitial space and more proteinaceous debris that filled the airspaces. Similar differences were observed when the gravity-dependent lung regions and non-dependent lung regions were analyzed separately (p < 0.05). The BAL neutrophil content was also higher in the LPS-supine group compared to the LPS-prone and control groups (p < 0.05). There were no significant differences in the wet/dry ratio and gas exchange levels.ConclusionsIn this experimental extrapulmonary mild ALI model, prone position ventilation for 1 h, when compared with supine position ventilation, was associated with lower lung inflammation and injury.

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