Protective effects of aerosolized pulmonary surfactant powder in a model of ventilator-induced lung injury.

Mechanical ventilation may contribute to the impairment of the pulmonary surfactant system, which is one of the mechanisms leading to the progression of acute lung injury. To investigate the potential protective effects of pulmonary surfactant in a rat model of ventilator-induced lung injury, the surfactant powder was aerosolized using an in-house made device designed to deliver the aerosolized powder to the inspiratory line of a rodent ventilator circuit. Rats were randomized to (i) administration of aerosolized recombinant surfactant protein C based pulmonary surfactant, (ii) intratracheally instillation of the same surfactant re-constituted in saline, and (iii) no treatment.

Improvement of an In Vitro Model to Assess Delivered Dose and Particle Size for a Vibrating Mesh Nebulizer During Mechanical Ventilation.

Background: In an in vitro model of mechanical ventilation with gravity-dependent filter position we observed artificially high delivered doses resulting from liquid droplet collection and precipitation of aerosolized drug. We sequentially modified the model to obtain accurate reproducible measurements of delivered dose and particle size at endotracheal tube exit.

Methods: Stepwise changes in the model included (1) altering the endotracheal tube position to a gravity-independent position, (2) adding fluid traps, (3) humidifying air near the test lung, and (4) simplifying test lung and filters.