Sharon L. Ho

Evaluation of Four Breath-Enhanced Nebulizers for Home Use

The objective of this study was to evaluate relative efficiency in vitro of four reusable breath-enhanced nebulizers (Pari LC Star, Medic-Aid Ventstream, Devilbiss PermaNeb, Salter Ultramist), and to integrate the in vitro performance data of the nebulizers with the respiratory patterns of four cystic fibrosis (CF) patients to compare efficiency in vivo of each device for each individual patient. Six nebulizers of each type were used to nebulize a solution of 2.5 mg (0.5 mL) albuterol with 3.5 mL of 0.9% saline. Total albuterol output and the rate of albuterol output of each device were measured until end-nebulization and for 4 min, respectively, using entrained flows from 0 to 20 L/min through the inspiratory valve of the device. Particle size distributions and the respirable fraction (RF) were evaluated by laser diffraction technique. Regression analysis of the change in rate of output and change in RF values with inspiratory flows was done to characterize each nebulizers performance over the complete range of interest. Actual breath tracings of four CF patients were integrated with the equations specific to the in vitro performance of each nebulizer and in vivo nebulizer efficiency was calculated. The change in efficiency in vitro from 0 to 20 L/min flow, respectively, was highest for the Star (44-57%) and lowest for the Ultramist (13-15%). The mean predicted efficiency in vivo for the Star was threefold that of the Ultramist. Although all four nebulizers are breath-enhanced in design, clearly there are measurable differences in the performance and efficiency of each type. The Pari LC Star nebulizer has proven to be the nebulizer of choice among the devices tested.

Effect of dead volume on the efficiency and the cost to deliver medications in cystic fibrosis with four disposable nebulizers

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 microm or less), nebulizer dead (residual) volume (VD), 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 VD following nebulization. COST ANALYSIS The expected pulmonary deposition (DE) was estimated, and incorporated with the material and labour costs to determine the cost effectiveness of each type of nebulizer. RESULTS With a DE 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 VD 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.