Evaluation of Aerosol Delivery Through an Oxygen Hood With Different Aerosol Inlet

Abstract

Background: Aerosol delivery to infants and children is a challenge due to their intolerance of the interface of a jet nebulizer. The effectiveness of aerosol delivery through an oxygen hood to infants has been proven. Yet, the influence of hood design and breath pattern on the aerosolized drug dose is not well explored. This study aimed to evaluated nebulized drug delivered through a facemask vs. a hood with infant and toddler breath pattern.

Methods: A breathing simulation (ASL 5000, Ingmar Medical Inc.) was used to generate infant (V_T 50 mL, respiratory rate 33 b/min, flow 13.1 L/min) and toddler (V_T 100 mL, respiratory rate 24 b/min, flow 14.5 L/min) breath patterns, and connected to either an infant or a child intubation mannequin. A bacterial filter was placed between the ASL 5000 and the bronchi of the mannequin to collect aerosolized drug particles. A united-dose of salbutamol (5 mg/2.5 mL) was placed in a small volume nebulizer (Galmed Inc., Taiwan) and diluted to 4 mL. The nebulizer was connected either to a pediatric facemask or a customized infant oxygen hood (22 x 25.5 x 20 cm), or a child oxygen hood (36 x 33 x 27 cm) with and without a cover, and a hole with 2.5 cm diameter at the center of the top, back, and side. Drug mass deposited in the filter and on the face of the mannequin was analyzed by UV spectrophotometry at 276 nm wavelength (n = 5). Statistical analyses were performed with ANOVA and Scheffe post hoc test, with a significance level of P < 0.05.

Results: Table 1 below illustrates comparisons between the inhaled drug dose and face dose between infant and child breath patterns. The inhaled dose was significantly greater with an oxygen hood and the nebulizer at the back for infant breath pattern, and with a facemask for toddler breath pattern (P < 0.001).

Conclusions: Aerosol delivery through an oxygen hood, with the nebulizer placed at the center of the back of the hood, is effective in the infant model. A facemask was more effective for toddler breath patterns.