Abstract
ABSTRACT
We describe an aerosol delivery system adapted to mechanical ventilation in pediatric intensive care but also applicable to adults and to experimental situations. A ServoVentilator 900C is used for mechanical ventilation. Aerosol particles are produced into the inspiratory line of the breathing circuit by an air jet nebulizer. The supply of compressed air to the nebulizer is controlled by pneumatic valves. These are operated by an electronic circuit which is connected to the ServoVentilator. The aerosol is produced during the expiratory phase only. The tubing in the inspiratory line of the breathing circuit between the nebulizer and the y–piece acts as a reservoir for the aerosol produced during an expiration, and the aerosol is delivered with the ensuing inspiration. A filter is placed in the expiratory line to trap excess aerosol particles.
The performance of the aerosol delivery system at different modes of ventilation was assessed by nebulizing a solution of budesonide and measuring the amount of drug delivered at the tip of the tracheal cannula. The distribution of aerosol in the airways was assessed by administration of radioactive aerosol to rabbits. The results showed aerosol delivery to be highly reproducible and to give minimum interference with the ventilator treatment.
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