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Introduction: Many devices (e.g., nebulizers and spacers) are used to deliver aerosol in a non-invasive ventilation circuit (NIV) without any special recommendation. The aim of the present work was to compare the doses delivered from seven different aerosol delivery systems when placed in the NIV using automatic continuous positive airway pressure (Auto-CPAP). Methods: Three spacers and three vibrating mesh nebulizers were compared to a Sidestream jet nebulizer (SIDE). Each device was placed proximal to a breathing simulator in a standard NIV circuit with a 500 ml tidal volume, 15 breaths/min and a 1:3 inspiratory-expiratory ratio. Two ml of salbutamol solution containing 10,000 lg was nebulized using Aerogen Pro (PRO), Aerogen Solo (SOLO), NIVO and SIDE. Twelve metered dose inhaler doses, containing 100 lg salbutamol each, were delivered using AeroChamber MV (AC), AeroChamber Vent (VC) and AeroChamber Mini (MC). Total emitted dose (TED) and its percentage were determined. Aerodynamic droplet characteristics were measured using cooled Andersen Cascade Impactor. Results: The vibrating mesh nebulizers used had significantly more (p\0.001) TED compared to the jet nebulizer. The spacers used had higher TED % (p\0.001) compared to the nebulizers. The fine particle fraction of SIDE was the highest (p = 0.021) and mass median aerodynamic diameter of the spacers was the smallest (p = 0.001). The fine particle dose from vibrating mesh nebulizers was the greatest (p = 0.02).

These similarities and differences between the three aerosol generators tested suggest that aerosol delivery methods should be carefully chosen or substituted in non-invasive ventilated patients.

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