Abstract
BACKGROUND: As the use of continuous high-frequency oscillation (CHFO) combined with nebulization during mechanical ventilation becomes more prevalent clinically, it is important to evaluate its aerosol delivery efficacy.
METHODS: A bench study was conducted simulating two adult and two pediatric conditions. The CHFO device (Metaneb) integrated into the inspiratory limb of a conventional critical care ventilator was attached to an endotracheal tube (ETT) with a collection filter and test lung. High frequency oscillation with high flow setting was used with jet nebulizers attached to the manifold, and a vibrating mesh nebulizer (VMN) placed between ETT and ventilator circuit versus at the inlet of the humidifier. Albuterol (2.5 mg in 3 mL) was nebulized for each condition (n=3). Drug was eluted from the collection filter and assayed with UV spectrophotometry (276 nm).
RESULTS: During CHFO, mean inhaled dose with jet nebulizers were very low (<2% with adult settings and <1% with pediatric settings). Across both adult and pediatric conditions, when VMN was placed between ETT and Y-piece during CHFO, inhaled dose was higher than that with VMN placed at the inlet of humidifier, median 11.1% (IQR 7.0% - 13.7%) vs median 6.0% (IQR 3.9% - 7.2%) P = .002, but still lower than the inhaled dose with VMN placed at inlet of humidifier with CHFO off, median 22.7% (IQR 19.5% - 25.4%) vs median 11.1% (IQR 7.0% - 13.7%) P<.001. Inhaled dose with the 10-year old scenario was higher than the 5-year old scenario in all settings except aerosol delivery via CHFO.
CONCLUSIONS: During invasive mechanical ventilation with CHFO, aerosol delivery with JN in the manifold resulted in marginal inhaled dose. VMN at the ETT during CHFO delivered 6 fold more aerosol than JN, while delivering only half of inhaled dose with VMN placed at the inlet of humidifier without CHFO.
- Continuous high-frequency oscillation
- aerosol delivery
- mechanical ventilation
- vibrating mesh nebulizer
- jet nebulizer.
Footnotes
- Correspondence
Ahmad Elshafei. Address: 1720 W. Harrison St, Room 1202 Lower Level Tower, Chicago, IL 60612, Email: Ahmad_A_Elshafei{at}rush.edu
- Received January 18, 2021.
- Accepted August 31, 2021.
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