Fill volume, humidification and heat effects on aerosol delivery and fugitive emissions during noninvasive ventilation

The aim of this study was to determine the-effect of fill-volume, heat-and-humidification on aerosol-delivery and fugitive-aerosol-emissions from nebulizers placed proximal to the patient in single-limb-non-invasive-ventilation (NIV) adult-model. We compared a vibrating-mesh-nebulizer (VMN) and jet-nebulizer (JN) placed proximal to breathing-simulator with adult-settings (I:E 1:3, 15 breaths.min−1, tidal-volume 500 mL). Ventilator was set to (20 cm.H2O peak-inspiratory-pressure, peak-expiratory-pressure 5cmH2O) in spontaneous-mode. Each nebulizer was used to compare total-inhaled-dose (TID) collected in inhalation-filter of 3 different fill-volumes (5000 μg salbutamol diluted to 1, 2 and 4 mL using normal-saline) and 3 heat-and-humidification-conditions (no-heat and no-humidification, humidification with no-heat and heat-with-humidification) using 1 mL respirable-solution containing 5000 μg salbutamol diluted to 2 mL using normal-saline. TID with 1, 2 and 4 mL fill-volumes were similar with VMN but increased upto twofold with JN (p < 0.01). No significant effect of humidification or heat on TID was found for both VMN and JN. Upto 50% of emitted-aerosol escaped through the fixed-orifice-leak. Efficiency of JN varied with fill-volume. In contrast, the lower-residual-volume of VMN produced similar efficiency across fill-volumes with higher TID than JN. No need to switch-off the humidifier for aerosol-delivery in NIV, since variations of heat-and-humidity did not impact TID with both nebulizer. However, fugitive-aerosol-emissions represent a potential-risk to both healthcare-providers and acute-care-environment.