Abstract
INTRODUCTION: Patients receiving invasive mechanical ventilation with an endotracheal tube (ETT) can often benefit from pharmaceutical aerosols; however, drug delivery through the ventilator circuit is known to be very inefficient. The objective of this study was to improve the delivery of aerosol through an invasive mechanical ventilation system by redesigning circuit components using a streamlining approach.
METHODS: Redesigned components were the T-connector interface between the nebulizer and ventilator line and the Y-connector leading to the ETT. The streamlining approach seeks to minimize aerosol deposition and loss by eliminating sharp changes in flow direction and tubing diameter that lead to flow disruption. Both in vitro experiments and computational fluid dynamic (CFD) simulations were applied to analyze deposition and emitted dose of drug for multiple droplet size distributions, flows, and ETT sizes used in adults.
RESULTS: The experimental results demonstrated that the streamlined components improved delivery through the circuit by factors ranging from 1.3 to 1.5 compared with a commercial system for adult ETT sizes of 8 and 9 mm. The overall delivery efficiency was based on the bimodal aspect of the aerosol distributions and could not be predicted by median diameter alone. CFD results indicated a 20-fold decrease in turbulence in the junction region for the streamlined Y resulting in a maximum 9-fold decrease in droplet deposition. The relative effectiveness of the streamlined designs was found to increase with increasing particle size and increasing flow, with a maximum improvement in emitted dose of 1.9-fold.
CONCLUSIONS: Streamlined components can significantly improve the delivery of pharmaceutical aerosols during mechanical ventilation based on an analysis of multiple aerosol generation devices, ETT sizes, and flows.
- pharmaceutical aerosols
- respiratory drug delivery
- mesh nebulizer
- mechanical ventilation
- T-connector
- Y-connector
- streamlined designs
- endotracheal tube
- improved aerosol delivery
Footnotes
- Correspondence: P Worth Longest PhD, Virginia Commonwealth University, 401 West Main Street, P.O. Box 843015, Richmond, VA 23284-3015. E-mail: pwlongest{at}vcu.edu.
Dr Golshahi presented a version of this work at the 19th International Congress of the International Society for Aerosols in Medicine, held April 2013 in Chapel Hill, North Carolina.
This study was supported by Award R01 HL107333 from the National Heart, Lung, and Blood Institute.
All authors are employees of Virginia Commonwealth University. Virginia Commonwealth University is seeking patent applications with respect to the technology described in this article, which, if licensed, may result in a financial interest to the authors.
The content of this article is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health.
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