Factors Influencing Aerosol Delivery During Invasive Ventilation

Area of Science:

• Pulmonary Medicine
• Biomedical Engineering
• Respiratory Care

Background:

• Aerosol delivery during mechanical ventilation is influenced by patient factors, device setup, and ventilator parameters.
• Optimizing aerosolized medication delivery is crucial for effective treatment in mechanically ventilated patients.

Purpose of the Study:

• To investigate the impact of ventilator settings, humidification, nebulizer position, bias flow, and circuit adapters on aerosol delivery during invasive mechanical ventilation.
• To determine which factors most significantly influence inhaled drug doses in various ventilation circuit conditions.

Main Methods:

• An in vitro model was used to test albuterol aerosol delivery via a vibrating mesh nebulizer under 28 conditions.
• Systematic evaluation across dry, dry with exhaled humidity, and heated humidified circuits.
• Variables included ventilator settings, nebulizer position, bias flow, and circuit adapters; drug deposition was quantified.

Main Results:

• High ventilator settings increased inhaled doses, particularly in dry circuits without humidity (11-22% increase).
• The influence of ventilator settings and nebulizer position decreased significantly with the introduction of exhaled or heated humidification.
• Bias flow and circuit adapter type had minimal impact, except under specific dry circuit conditions.

Conclusions:

• Ventilator settings and nebulizer placement are key determinants of aerosol delivery in dry, non-humidified circuits.
• Humidification (exhaled or heated) mitigates the impact of ventilator settings and nebulizer position, leading to more consistent aerosol delivery.
• Bias flow and adapter design appear to have a minor role in overall aerosol deposition during invasive mechanical ventilation.