In vitro comparison of the circulaire and AeroTee to a traditional nebulizer T-piece with corrugated tubing.

BACKGROUND: Nebulizers are a popular means of delivering aerosolized medication, primarily albuterol, to the bronchial airways of patients, and there has been extensive research done on numerous nebulizers used with nebulizer T-pieces and corrugated tubing. Very little research has been performed on other types of nebulizer delivery systems and there is no substantial information on how effective various nebulizer delivery systems are in terms of the quantity and particle size of aerosolized medication delivered to the patient. In this study the Circulaire and the AeroTee, two devices that rely on bags to store aerosol during patient exhalation, are evaluated and compared to the conventional nebulizer T-piece with corrugated tubing. METHODS: Three each of the nebulizer T-piece with corrugated tubing, the Circulaire, and the AeroTee were sampled using 3 Vixone nebulizers. Each one of the 3 nebulizer delivery systems used the same 3 Vixone nebulizers. Each nebulizer delivery system was evaluated by connecting a constant-flow vacuum and compressed gas source cycled to simulate patient breathing at a respiratory rate of 14 breaths/min and an inspiration-expiration ratio of 1:2. Medication delivered was determined by sampling a portion of the simulated patient's flow onto a membrane filter and calculating the total medication received by the patient. Particle size was determined by sampling with a cascade impactor under ambient conditions. RESULTS: The Circulaire delivered significantly less medication than the nebulizer T-piece with corrugated tubing (p < 0.001), whereas the AeroTee delivered substantially more medication than the nebulizer T-piece with corrugated tubing (p < 0.001). The particle size delivered by the Circulaire was significantly smaller than that of the nebulizer T-piece with corrugated tubing (p < 0.001), whereas the AeroTee delivered particle size equivalent to a nebulizer T-piece with corrugated tubing (p = 0.82). CONCLUSION: There are clinically important differences between nebulizer delivery systems. When evaluating the optimum means for delivering aerosolized medication, equal consideration should be given to both the brand of nebulizer and the nebulizer delivery system.

Continuous nebulization therapy for asthma with aerosols of beta2 agonists.

BACKGROUND: Various studies have demonstrated the benefits of continuous nebulization therapy for delivering aerosols of the beta2 agonists such as terbutaline sulfate or albuterol sulfate to patients with severe asthma and/or impending respiratory failure. OBJECTIVE: The purpose of this investigation was to explicate the operational factors associated with the use of nebulizers for extended aerosol respiratory therapy including those factors that affect the prescribed aerosol dosages and the relationship to actual delivery of prescribed drugs to the respiratory airways of the lungs of a patient under treatment conditions. METHODS: Operational characteristics and methods have been investigated for use of long-running nebulizers for continuous nebulization therapy. Factors considered were particle size distribution, setup conditions, aerosolization concentrations and rates, delivery fraction of aerosol reaching patient, and changes in medication concentration during extended operation. With a large volume nebulizer, aerosols can be delivered to the patient without dilution via a standard open mask for up to eight hours without refill. The pneumatic HEART nebulizer with 240 mL reservoir was evaluated. RESULTS: The nebulizer was operated from a single compressed air or oxygen source and found to provide from 10 to 15 L/min of aerosol with 38 to 50 microL of aerosolized medicine per liter of air (or oxygen) and utilize from 30 to 56 mL/hour of medicinal liquid. The mass median aerodynamic diameter of the aerosol droplets was found to be about 2.0 microm (sigma(g) = 2.7). Delivery efficiency to the patient mask was about 90%. The aerosolized medicine delivered to the patient can be increased by adjusting the flow rate of the gas source or changing the solution concentration of medicine. Typically, several milligrams of drug can be delivered to the patient as inhaled aerosol per hour of treatment of which about one-quarter can be expected to be deposited in the lungs. During eight hours of operation the concentration of medicinal solution increased by about a factor of two because of water evaporation. CONCLUSIONS: Continuous nebulization therapy is an important means of treating patients with severe asthma. Dosage criteria can be established based on the operating characteristics of the nebulizer system, drug solution concentration, and patient respiration.