Albuterol Aerosol Delivered via Metered-Dose Inhaler to Intubated Pediatric Models of 3 Ages, With 4 Spacer Designs

OBJECTIVE: To determine the amount of albuterol, in various particle size ranges, delivered from a hydrofluoroalkane-propelled metered-dose inhaler (Airomir) in 3 models of pediatric intubation (ages 8 months, 4 years, and 16 years) using 4 types of aerosol reservoir: 3 spacers (ACE, AeroChamber HC MV, metal NebuChamber without 1-way valve) and 1 holding chamber (metal NebuChamber with 1-way valve).

METHODS: Five reservoirs of each type were tested with albuterol sulfate delivered via metered-dose inhaler that delivers 100 μg of albuterol per actuation. Each reservoir was connected to an endotracheal tube (ETT) that corresponded to the given patient age (8 months = 4 French; 4 years = 5 French; 16 years = 7.5 French) and to a valved system that allowed connection of the ETT to a cascade impactor. Simulated tidal volumes representative of children of the given ages were passed through the reservoir. Both the cascade impactor and the ETT were enclosed within a 100% humidity, 37° C environment.

RESULTS: For the total amount of albuterol inhaled onto the impactor, and both the 1.1-4.7 μm and 1.1-3.3 μm inhaled fine-particle fractions, the NebuChamber-with-valve showed significantly greater drug delivery than the NebuChamber-without-valve, the AeroChamber HC MV, or the ACE (p < 0.001). Among the reservoirs without valves the NebuChamber showed significantly greater delivery than the AeroChamber HC MV or ACE (p < 0.001) for total drug deposition and for both the 1.1-4.7 μm and 1.1-3.3 μm fine-particle fractions. These results were consistent over all age groups. The AeroChamber HC MV had significantly greater delivery (total deposition) than the ACE (p < 0.001), except in the 4-year-old model. There were no significant differences between the AeroChamber HC MV and the ACE for either the 1.1-4.7 μm or the 1.1-3.3 μm fine-particle fraction.

CONCLUSIONS: An aerosol reservoir with 1-way valve positioned between the spacer and the ETT improved the amount of inhaled albuterol 300–900%, compared to the other reservoirs.