Effect of Age Related Breathing Parameters on the Performance of a New Nebulizer System: An In-Vitro Study

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Abstract
A new continuously operated nebulizer system (PARI LC) has been designed for use in patients from one month of age to adulthood. Two different configurations are available, one with a son silicon face mask for use in babies and infants (three different mask sizes), and one with a mouthpiece with integrated expiratory valve. The nebulizer is based on an open-vent technology in combination with a valve system which enables the entrained air to pass through the nebulizing chamber, thus increasing aerosol output during inspiration. In this study the effect of tidal volume and breathing frequency on the nebulizer efficiency has been investigated by using a breath simulator at fixed 50% inspiration and 50% expiration cycles. Sodium fluoride was used as a tracer and analysed from filters simulating the aerosol to be inhaled by a patient (aerosol delivered) and the amount exhausted to the environment (aerosol wasted). Each configuration of the nebulizer was tested by simulating the relevant breathing conditions in a range from 50 to 500 ml tidal volume at variable frequency. The results demonstrate that for an average inspiratory flow between 15 and 19 1/min approximately 70% of the aerosol produced will be inhaled due to the air entrainment effect and the valve system. With decreasing inspiratory flow the air entrainment effect and the resulting proportion of aerosol delivered are reduced. However, since the deadspace ventilated during exhalation is minimized in the systems, still approximately 20 to 40% of the total aerosol can be inhaled at an average inspiratory flow as low as 4 to 5 1/min.