The Effect of Aerosol Devices and Administration Techniques on Drug Delivery in a Simulated Spontaneously Breathing Pediatric Model with a Tracheostomy

Background: Evidence on aerosol delivery via tracheostomy is lacking. The purpose of this study was to evaluate the effect of aerosol device and administration technique on drug delivery in a simulated spontaneously breathing pediatric model with tracheostomy. Methods: Delivery efficiencies during spontaneous breathing with assisted and unassisted administration techniques were compared using the jet nebulizer (JN- MicroMist), vibrating mesh nebulizer (VMN- Aeroneb Solo) and pressurized metered-dose inhaler (pMDI- ProAirHFA). The direct administration of aerosols in spontaneously breathing patients (unassisted technique) was compared to administration of aerosol therapy via a manual resuscitation bag (assisted technique) attached to the aerosol delivery device and synchronized with inspiration. An in-vitro lung model consisted of an uncuffed tracheostomy tube (4.5 mmID) was attached to a collecting filter (Respirgard) which was connected to a dual-chamber test lung (TTL) and a ventilator (Hamilton). The breathing parameters of a 2 years-old child were set at an RR of 25 breaths/min, a Vt of 150 mL, a Ti of 0.8 sec and PIF of 20 L/min. Albuterol sulfate was administered with each nebulizer (2.5 mg/3 ml) and pMDI with spacer (4 puffs, 108 µg/puff). Each aerosol device was tested five times with both administration techniques (n=5). Drug collected on the filter was eluted with 0.1 N HCl and analyzed via spectrophotometry. Results: The amount of aerosol deposited in the filter was quantified and expressed as inhaled mass and inhaled mass percent. The pMDI with spacer had the highest inhaled mass percent, while the VMN had the highest inhaled mass. The results of this study also found that JN had the least efficient aerosol device used in this study. The trend of higher deposition with unassisted versus assisted administration of aerosol was not significant (p\u3e0.05). Conclusions: Drug deposited distal to the tracheostomy tube with JN was lesser than either VMN or pMDI. Delivery efficiency was similar with unassisted and assisted aerosol administration technique in this in vitro pediatric model