EFFECT OF AGE-RELATED BREATHING PARAMETERS ON THE PERFORMANCE OF A NEW NEBULIZER SYSTEM - AN IN-VITRO STUDY

A new continuously operated nebulizer system (PARI LC) has been design ed for use in patients from one month of age to adulthood. Two differe nt configurations are available, one with a soft 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 en ables the entrained air to pass through the nebulizing chamber, thus i ncreasing aerosol output during inspiration. In this study the effect of tidal volume and breathing frequency on the nebulizer efficiency ha s been investigated by using a breath simulator at fixed 50% inspirati on and 50% expiration cycles. Sodium fluoride was used as a tracer and analysed from filters simulating the aerosol to be inhaled by a patie nt (aerosol delivered) and the amount exhausted to the environment (ae rosol wasted). Each configuration of the nebulizer was tested by simul ating the relevant breathing conditions in a range from 50 to 500 mi t idal volume at variable frequency. The results demonstrate that for an average inspiratory now between 15 and 19 l/min approximately 70% of the aerosol produced will be inhaled due to the air entrainment effect and the valve system. With decreasing inspiratory now the air entrain ment effect and the resulting proportion of aerosol delivered are redu ced. However, since the deadspace ventilated during exhalation is mini mized in the systems, still approximately 20 to 40% of the total aeros ol can be inhaled at an average inspiratory now as low as 4 to 5 l/min .