In-vitro comparison of 4 large-volume nebulizers in 8 hours of continuous nebulization

Continuous albuterol nebulization has become the standard of care for patients with status asthmaticus. Predictable albuterol delivery is paramount for effective therapy. We compared the aerosol characteristics, solution output, and albuterol output of 4 brands of large-volume nebulizer.

We studied 6 units of the following nebulizer brands: AirLife Misty Finity (Cardinal Health), Flo-Mist (Smith's Medical), Heart (WestMed), and Hope (B&B Medical Technologies). All the nebulizers were operated according to the manufacturers' recommendations and connected to 180-cm of flexible corrugated tubing. We diluted 80 mg of albuterol sulfate nebulizer solution in saline solution, per the manufacturer's recommendations (admixture required to deliver 10 mg/h). Solution output, solution retained in the tubing, reservoir albuterol concentration, and albuterol output were determined hourly for 8 hours. The ambient and aerosol temperatures were recorded every 30 minutes. The target outputs were ± 20% of the manufacturer's specification. Aerosol characteristics were determined via cascade impaction, with aerosol collected between 60 and 70 min of operation.

All the aerosols had an adequate size for pulmonary deposition. The increase in reservoir albuterol concentration was < 20% for the first 4 hours. There were no significant differences in achieving the target albuterol output, but none of the nebulizers achieved the target albuterol output during the 1st hour. Albuterol output was similar between the nebulizers for the first 5 hours. There were no differences in reaching the target solution output. The Misty Finity and Hope had a solution output consistent with the manufacturers' specifications. The amount of solution retained in the tubing was greatest with the Heart (23%); other nebulizers' tubing-retained-solution ranged from 6-9%. Albuterol output corrected for the tubing-retained solution rendered similar results. Aerosol temperature decreased with aerosol production and increased in the corrugated tubing, but was below the ambient temperature at the patient interface.

The tested nebulizers had similar performance during the first 5 hours. The nebulizer solution might need to be replaced if treatment is planned for longer period. The Misty Finity and Hope nebulizers had a more consistent solution output.