Comparison Between Various Jet Nebulizers Designed to Provide a Shorter Aerosol Treatment Time

Background: Providing aerosol therapy in a shorter time span can provide more rapid patient relief and improve workflow in a busy respiratory care department. Breath-enhanced (BE) nebulizers improve the flow to the patient and deliver more medication to the distal airway. The purpose of this study is to determine which nebulizer provides the optimal combination of both short treatment time and ability to provide the greatest amount of aerosol within the respirable range. Methods: Three different nebulizers were evaluated (no. = 5); two breath-enhanced (BE) jet nebulizers (MC300 and TurboMist), and one continuous (CONT) jet nebulizer (Misty Max 10) as control. Each nebulizer was loaded with 3 mL of 2.5 mg albuterol sulfate solution with the gas flow set to deliver 8 L/min. The nebulizer was connected to a spontaneous breathing servo lung model (ASL 5000) with the following settings: VT 500 mL, frequency 10, and I:E ratio of 1:2. A filter was placed between the mouthpiece of the nebulizer and the test lung to capture inspired aerosol. Gas flow was stopped every minute and the filter exchanged for a fresh one. Each nebulizer was run for 1 min after sputter was observed. Nebulizer output was determined by rinsing the filter medium in methanol and then placing the filtrate into HPLC. Parallel measurements of fine droplet fraction < 4.7 μm diameter (FDF < 4.7 μm) were made using a Spraytec laser diffractometer. Fine droplet mass (FDM < 4.7 μm) was determined as the product of recovered mass and FDF < 4.7 μm. Results: The TurboMist had the shortest time to sputter with the Misty Max 10 the longest (161.4 ± 6.6 to 287.0 ± 8.7 s, P < .01). Total output mass for each nebulizer was similar for all 3 nebulizers (403.2 ± 42.9 MC300, 339.8 ± 26.3 Misty Max 10, and 333.1 ± 19.6 μg TurboMist, P > .05). However, the FDF < 4.7 μm was significantly higher for one BE device (304.0 ± 32.3 MC300, 202.5 ± 11.9 TurboMist, and 262.5 ± 20.3 μg Misty Max 10, P < .01). Nebulizer efficiency was determined to be FDF < 4.7 μm divided by total output. Overall efficiency of each nebulizer was small (12 ± 1% MC300, 10 ± 1% Misty Max 10, and 8 ± 0% TurboMist, P < .01). Conclusions: All nebulizers tested were fast nebulizers. Device output and medication delivery to the distal airways must be considered when selecting an aerosol generator along with time. Poor aerosol delivery could require more frequent treatments which would negate the benefit of using a higher output nebulizer.Table 1: Fine droplet mass (particles < 4.7 μm ) per device.Figure 1: Median fine droplet mass output by nebulizer