Effects of mechanical ventilation of isolated mouse lungs on surfactant and inflammatory cytokines

Mechanical ventilation of the lung is an essential but potentially harmful therapeutic intervention for patients with acute respiratory distress syndr ome. The objective of the current study was to establish and characterize a n isolated mouse lung model to study the harmful effects of mechanical vent ilation. Lungs were isolated from BalbC mice and randomized to either a nonventilate d group, a conventionally ventilated group (tidal volume 7 mL.kg(-1), 4 cm positive end-expiratory pressure (PEEP)) or an injuriously ventilated group (20 mL.kg(-1), 0 cm PEEP). Lungs were subsequently analysed for lung compl iance, morphology, surfactant composition and inflammatory cytokines. Injurious ventilation resulted in significant lung dysfunction, which mas a ssociated with a significant increase in pulmonary surfactant, and surfacta nt small aggregates compared to the other two groups. Injurious ventilation also led to a significantly increased concentration of interleukin-6 and t umour necrosis factor-a in the lavage. It was concluded that the injurious effects of mechanical ventilation can e ffectively be studied in isolated mouse lung, which offers the potential of studying genetically altered animals. It mas also concluded that in this m odel, the lung injury is, in part, mediated by the surfactant system and th e release of inflammatory mediators.