Quantifying Aerosol Delivery Through a Tracheostomy Interface Using Jet and Vibrating Mesh Nebulizers in a Simulated Spontaneously Breathing Pediatric Tracheostomy Model

Abstract

Background:

The purpose of this study was to evaluate aerosol delivery efficiency through a tracheostomy interface attached to a jet nebulizer, vibrating mesh nebulizer (VMN) combined with an aerosol adapter, and VMN combined with a heated humidified breathing circuit in a simulated spontaneously breathing pediatric model with tracheostomy tube (TT). Aerosol delivery at different flow output levels was also investigated with VMN.

Methods:

An in vitro model consisting of a pediatric manikin with an anatomically correct airway and uncuffed TT (5.0-mm inner diameter) was connected to a lung simulator via a collecting filter at the level of the carina to simulate a spontaneously breathing child weighing 20 kg (V_T 140 mL, RR 24, I:E ratio 1:2.5). Albuterol sulfate was administered using a jet nebulizer (AirLife Side-Stream, 2.5 mg/3.5 mL) and VMN (Aerogen Solo, 2.5 mg/1.5 mL). The jet nebulizer was attached to the TT via a tracheostomy interface (OPT970, Fisher & Paykel) and operated at 6 L/min with a resulting flow output of 13 L/min during nebulization. The VMN was attached to the TT via the tracheostomy interface with an aerosol adapter (Aerogen Ultra) or heated humidified breathing circuit (RT232, Fisher & Paykel) with VMN placed at inlet of humidifier (Fisher & Paykel 850) set at 37 C. In both VMN conditions, aerosol was delivered through the tracheostomy interface at flows of 2, 6, and 13 L/min. Prior to testing, flows were verified with a mass flow meter (TSI, Shoreview, MN). Flow was discontinued at the end of nebulization. Each device was tested in triplicate. Drug was analyzed by spectrophotometry (276 nm). ANOVA followed by Holm-Sidak multiple comparison was used for data analysis, P < .05.

Results:

There was no significant difference in the percent of inhaled albuterol between the jet nebulizer (2.88 ± 0.1%), VMN with aerosol adapter at 13 L/min (2.87 ± 0.3%) or VMN with heated humidified breathing circuit at 6 L/min (2.2 ± 0.3%). However, the VMN combined with aerosol adapter delivered significantly more medication than any other tested condition at output flows of 2 L/min (7.01 ± 0.7%) and 6 L/min (6.49 ± 0.5%)(P < .05). Aerosol delivery at 2 and 13 L/min with the VMN combined with a heated humidified breathing circuit was significantly less than any other tested condition.

Conclusions:

In this pediatric tracheostomy model, the inhaled dose delivered through a tracheostomy interface was greatest when aerosol was generated with the VMN combined with aerosol adapter at output flows of 2 and 6 L/min.