Previous studies have demonstrated that mechanical ventilation is an important factor in the development of lung injury. The purpose of this study was to determine if bacterial pneumonia and mechanical ventilation synergistically lead to the development of acute lung injury (ALI) in order to elucidate immunopathogenic mechanisms in a clinically relevant model. (Table)
Methods C57/Bl6 mice were administered Staphylococcus aureus using an oropharyngeal aspiration model and subsequently mechanically ventilated (tidal volume=10 mg/kg, rate=150/min, end-expiratory pressure=0, FIO2=0.21) for 6 hours.
Bacterial Clearance and Dissemination - No differences in bacterial clearance were seen between the ventilated and non-ventilated mice. Cultures of spleen homogenates were negative in both groups at 6 hours.
Conclusions Mechanical ventilation augments lung inflammation, without affecting bacterial clearance or extra-pulmonary bacterial dissemination, in a murine model of ventilator-associated bacterial pneumonia (VAP). This model will be useful for elucidation of immunologic mechanisms involved in the pathogenesis of VAP.