Effect of Dead Volume on the Efficiency and the Cost to Deliver Medications in Cystic Fibrosis with Four Disposable Nebulizers

Abstract

OBJECTIVES: To evaluate the factors that affect nebulizer efficiency and to compare the relative cost effectiveness of nebulized medications used in the treatment of cystic fibrosis (CF), delivered by four types of disposable jet nebulizers that are widely used in hospitals.DESIGN: The Hudson 1730 Updraft II, Baxter Misty-Neb, Marquest Whisper Jet (WJ), and Marquest Acorn II were evaluated in terms of respirable aerosol output (particles 5 µm or less), nebulizer dead (residual) volume (V_D), and time for complete nebulization using saline, salbutamol and tobramycin at flows of 6 and 8 L/min. The respirable fraction (RF) was determined by laser diffraction, and drug output was calculated from the initial volume and concentration of the drug in the nebulizer minus the product of final drug concentration and the V_D following nebulization.COST ANALYSIS: The expected pulmonary deposition (D_E) was estimated, and incorporated with the material and labour costs to determine the cost effectiveness of each type of nebulizer.RESULTS: With a D_E greater than two times that of the WJ at a cost of 2.4 times less, the Updraft II proved most efficient and cost effective of all the nebulizers evaluated in this study.CONCLUSIONS: The cost effectiveness of each nebulizer was determined by its efficiency, which in turn was predominantly related to its V_D and RF at each flow. The efficiencies of these four devices were different and could not have been predicted from specifications provided by the respective manufacturers.