title: Quantifying Aerosol Delivery in Simulated Spontaneously Breathing Patients With Tracheostomy Using Different Humidification Systems With or Without Exhaled Humidity.
abstract: BACKGROUND
  Aerosol and humidification therapy are used in long-term airway management of critically ill patients with a tracheostomy. The purpose of this study was to determine delivery efficiency of jet and mesh nebulizers combined with different humidification systems in a model of a spontaneously breathing tracheotomized adult with or without exhaled heated humidity.
  
  
  METHODS
  An in vitro model was constructed to simulate a spontaneously breathing adult (tidal volume, 400 mL; breathing frequency, 20 breaths/min; inspiratory-expiratory ratio, 1:2) with a tracheostomy using a teaching manikin attached to a test lung through a collecting filter (Vital Signs Respirgard II). Exhaled heat and humidity were simulated using a cascade humidifier set to deliver 37°C and >95% relative humidity. Albuterol sulfate (2.5 mg/3 mL) was administered with a jet nebulizer (AirLife Misty Max) operated at 10 L/min and a mesh nebulizer (Aeroneb Solo) using a heated pass-over humidifier, unheated large volume humidifier both at 40 L/min output and heat-and-moisture exchanger. Inhaled drug eluted from the filter was analyzed via spectrophotometry (276 nm).
  
  
  RESULTS
  Delivery efficiency of the jet nebulizer was less than that of the mesh nebulizer under all conditions (P < .05). Aerosol delivery with each nebulizer was greatest on room air and lowest when heated humidifiers with higher flows were used. Exhaled humidity decreased drug delivery up to 44%.
  
  
  CONCLUSIONS
  The jet nebulizer was less efficient than the mesh nebulizer in all conditions tested in this study. Aerosol deposition with each nebulizer was lowest with the heated humidifier with high flow. Exhaled humidity reduced inhaled dose of drug compared with a standard model with nonheated/nonhumidified exhalation. Further clinical research is warranted to understand the impact of exhaled humidity on aerosol drug delivery in spontaneously breathing patients with tracheostomy using different types of humidifiers.
authors.affiliation: Department of Respiratory Therapy, Georgia State University, Atlanta, Georgia. arzuari@hotmail.com.
authors.forename: Arzu
authors.initials: A
authors.lastname: Ari
authors.affiliation: Department of Respiratory Therapy, Georgia State University, Atlanta, Georgia.
authors.forename: Robert
authors.initials: R
authors.lastname: Harwood
authors.affiliation: Department of Respiratory Therapy, Georgia State University, Atlanta, Georgia.
authors.forename: Meryl
authors.initials: M
authors.lastname: Sheard
authors.affiliation: University of Dammam, Dammam, Saudi Arabia.
authors.forename: Maher Mubarak
authors.initials: MM
authors.lastname: Alquaimi
authors.affiliation: Department of Respiratory Therapy, Georgia State University, Atlanta, Georgia.
authors.forename: Bshayer
authors.initials: B
authors.lastname: Alhamad
authors.affiliation: James B Fink, LLC, San Mateo, California, and the Department of Respiratory Therapy, Georgia State University, Atlanta, Georgia.
authors.forename: James B
authors.initials: JB
authors.lastname: Fink
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols / Q000008:administration & dosage*; D000420:Albuterol / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D016503:Drug Delivery Systems / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D000068998:Humidifiers; D006813:Humidity; D008348:Manikins; D009330:Nebulizers and Vaporizers; D012119:Respiration; D014139:Tracheostomy
chemical_list: D000336:Aerosols; D001993:Bronchodilator Agents; D000420:Albuterol
keywords: aerosols; and tracheostomy; drug delivery; humidification; nebulizers