Fig. 6

Schematic representation of nebulizer potential position in different NIV systems (a–d) and the effect on the amount of inhalable of drug (E–F). V = valve, that is the element used to produce the pressure when crossed by the flow, P = patient, HUM = humidifier. The dashed line represents the flow of one representative breath. The red line represents the bias flow for a standard mechanical ventilator in proportion to the breathing flow. Pink dots are aerosol particles produced by the nebulizer and dispersed into the flow. Aerosol particles are distributed directly into the bias flow when the nebulizer is placed along the inspiratory limb (e). In contrast, aerosol particles are not removed by the bias flow and are moved only by the breathing flow of the baby when the nebulizer is placed between the patient Y-piece and the airway opening (f). In principle, only the particles that can be inhaled are particles produced by the nebulizer and suspended in the airflow during inspiration. This concept is represented graphically by particles enclosed in inspiration: the concentration of the particles is greater when the nebulizer is placed between the Y piece and the airway opening, compared to when the nebulizer is positioned within the inspiratory limb