Aerosol Delivery via Continuous High-Frequency Oscillation During Mechanical Ventilation

Area of Science:

• Respiratory Care
• Pulmonary Medicine
• Biomedical Engineering

Background:

• Mechanical ventilation is increasingly combined with continuous high-frequency oscillation (cHFO) and nebulization.
• Evaluating aerosol delivery efficacy during cHFO is crucial for clinical practice.

Purpose of the Study:

• To assess aerosol delivery efficiency of jet and vibrating mesh nebulizers during cHFO in simulated adult and pediatric mechanical ventilation.
• To compare different nebulizer placements and the impact of cHFO on inhaled drug doses.

Main Methods:

• A bench study simulated adult and pediatric conditions using a test lung and endotracheal tube (ETT).
• cHFO was applied with jet nebulizers and vibrating mesh nebulizers (VMN) at various positions (manifold, ETT, humidifier inlet).
• Albuterol dose was measured using ultraviolet spectrophotometry after elution from a collection filter.

Main Results:

• Jet nebulizers delivered a marginal inhaled dose (<2% adult, <1% pediatric) during cHFO.
• VMN placed between ETT and Y-piece during cHFO yielded higher doses (median 11.1%) than at the humidifier inlet (median 6.0%).
• VMN delivery during cHFO was significantly lower than without cHFO (median 11.1% vs. 22.7%).

Conclusions:

• Jet nebulizers provide minimal aerosol delivery during invasive mechanical ventilation with cHFO.
• VMN at the ETT during cHFO offers a 6-fold increase over jet nebulizers but half the dose compared to VMN without cHFO.
• Optimizing aerosol delivery during cHFO requires strategic nebulizer placement and consideration of oscillation settings.