In vitro characteristics of tobramycin aerosol from ultrasonic and jet nebulizers

Abstract

Study Objective. To compare the in vitro performance of an ultrasonic nebulizer and a jet nebulizer in producing a respirable aerosol of tobramycin solution for injection. Design. In vitro observational study. Devices. Ultrasonic and jet nebulizers. Intervention. Output was determined by measuring the difference in nebulizer weight before and after nebulizing 3 ml of tobramycin injection solution. Mass median aerodynamic diameter (MMAD) and respirable mass were determined by sampling tobramycin aerosol into a cascade impactor. Measurements and Main Results. Mean (SD) output was 1.14 (0.09) ml/minute for the ultrasonic nebulizer and 0.64 (0.08) ml/minute (p<0.001) for the jet nebulizer. Mean MMAD for the jet nebulizer (2.31 [0.10] μm) was less than that of the ultrasonic nebulizer (2.81 [0.17] μm, p<0.001). The majority of tobramycin aerosol produced was in the respirable range for both the ultrasonic (65.1% [4.10%]) and jet (60.6% [0.73%], p=0.008) nebulizers. Conclusion. Despite small, clinically unimportant differences in aerosol size and respirable fraction, either device would be acceptable to administer tobramycin injection solution.