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.Key Words: Aerosol; Cost effectiveness; Cystic fibrosis; Dead volume; Efficiency; Nebulizer Effet de l'espace mort sur la performance et le coût de l'administration de médicaments aux patients atteints de fibrose kystique du pancréas avec quatre nébuliseurs jetables OBJECTIFS : Évaluer les facteurs qui modifient la performance d'un nébuliseur et comparer la rentabilité relative des médicaments nébulisés et utilisés pour traiter la fibrose kystique du pancréas (FKP) au moyen de quatre types de nébuliseurs jetables largement utilisés dans les hôpitaux. Updraft II, Baxter Misty-Neb, Marquest Whisper Jet (WJ) et Marquest Acorn II ont été évalués relativement à leur production de gouttelettes respirables (particules de 5 µm et moins), à l'espace mort (V D ) résiduel du nébuliseur, et au temps requis pour une nébuli-voir page suivante I nhalational aerosol therapy is widely used as a method to deliver bronchodilators and antibiotics in the treatment of cystic fibrosis (CF). It is commonly accepted that the ideal particle size for pulmonary deposition at the level of the lower airways is within the range of 1 and 5 mm in diameter, and, from this concept, the respirable fraction (RF) of aerosol output has been defined as the mass of drug carried in droplets 5 mm or less (1-3), although it is recognized that data in the pediatric age group are limited and in vitro data may not correlate with in vivo data (4). While the combination of particle size distribution, gas flow driving the nebulizer and the fill volume ...

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“…Several current disposable nebulizers do create particle sizes below 5 μm, as measured by laser diffraction. 16 …”

Drug administration by jet nebulization

“…Such information is frequently not available, making an appropriate choice of equipment difficult. 12 While most aerosol droplets in nature are formed by condensation of a supersaturated gas around a suspended nucleus, e.g., cloud formation, the production of droplets of medical aerosol involves a different mechanism. Basically, nebulization can be accomplished by ultrasonic or jet nebulization.…”

“…15,16 This places considerable physical demands on the equipment. Repetitive use of disposable devices in the laboratory can lead to degradation of the particle size distribution when the device is driven hard from a 50 psi source of compressed air 12 although, with the use of a compressor in the home environment, the clinical significance of this is questionable. 17,18 However, the plastic in disposable devices may not stand up to proper cleaning, and failure to adequately clean the device leads to significant bacterial contamination.…”

“…12 This phenomenon is most probably due to the differences in surface tension in the agents being nebulized. 5 All of this leaves the clinician with a dilemma in making the appropriate choice of device for clinical use in CF.…”

“…46 In the rhDNase studies cited above, although the dose of medication was standardized, the use of several different models of nebulizers could have resulted in a pulmonary deposition of drug that was highly variable and dependent upon the efficiency of the nebulizer used. 12 The different efficiency of each model might have effectively resulted in nonstandardized doses and, thus, possibly contributed to the variation in outcome that was seen. Three nebulizer systems, including two disposable nebulizers and one reusable nebulizer, have been approved for the delivery of rhDNase in clinical trials, since similar in vitro efficiency of these devices was reported.…”