title: Medical nebulizer performance: effects of cascade impactor temperature.
abstract: BACKGROUND
  During operation of a jet nebulizer, the temperature of the nebulizer outlet could decrease by more than 10 degrees C, depending on the nebulizer type and operating conditions, such as driving flow rate and fill volume. The droplet size distribution generated from the nebulizer can be measured by a cascade impactor. However, when the cascade impactor is operated at ambient room temperature, the droplets could evaporate because of the temperature difference between the nebulizer outlet and the body of the impactor.
  
  
  METHODS
  An 8-stage cascade impactor was used to measure the particle size distribution from 4 different types of jet nebulizer (LC Plus, Side-Stream, VixOne, and Micromist) in 2 temperature conditions: ambient (22 degrees C) and low (10 degrees C). Two different formulations, albuterol (aqueous solution) and budesonide (suspension), were used.
  
  
  RESULTS
  There was a significantly larger (p < 0.05) mass median aerodynamic diameter and smaller respirable fraction for each nebulizer with the impactor at low temperature than with the impactor at ambient temperature. The mass median aerodynamic diameter of the nebulizers with the impactor operating at low temperature appeared 15-130% larger than with the impactor operating at ambient temperature, for both formulations. The respirable fraction also changed from 10% when the impactor was operated at low temperature to 65% when the impactor was operated at ambient temperature.
  
  
  CONCLUSIONS
  The results provide important information for the use of a cascade impactor to measure the particle-size distribution of nebulizer aerosols.
authors.affiliation: Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive SE, Albuquerque NM 87108, USA. yzhou@lrri.org
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.forename: Amitkumar
authors.initials: A
authors.lastname: Ahuja
authors.forename: Clinton M
authors.initials: CM
authors.lastname: Irvin
authors.forename: Dean A
authors.initials: DA
authors.lastname: Kracko
authors.forename: Jacob D
authors.initials: JD
authors.lastname: McDonald
authors.forename: Yung-Sung
authors.initials: YS
authors.lastname: Cheng
mesh_terms: D000280:Administration, Inhalation; D000420:Albuterol / Q000008:administration & dosage; D001993:Bronchodilator Agents / Q000008:administration & dosage; D019819:Budesonide / Q000008:administration & dosage; D006801:Humans; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D012107:Research Design; D012138:Respiratory Therapy; D013696:Temperature; D014481:United States
chemical_list: D001993:Bronchodilator Agents; D019819:Budesonide; D000420:Albuterol