PT  - JOURNAL ARTICLE
AU  - P. Worth Longest
AU  - Mandana Azimi
AU  - Laleh Golshahi
AU  - Michael Hindle
TI  - Improving Aerosol Drug Delivery During Invasive Mechanical Ventilation with Redesigned Components
AID  - 10.4187/respcare.02782
DP  - 2013 Oct 08
TA  - Respiratory Care
PG  - respcare.02782
4099  - http://rc.rcjournal.com/content/early/2013/10/08/respcare.02782.short
4100  - http://rc.rcjournal.com/content/early/2013/10/08/respcare.02782.full
AB  - Background. Patients receiving invasive mechanical ventilation with an endotracheal tube (ETT) can often benefit from pharmaceutical aerosols; however, drug delivery through the ventilation 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, flow rates, and ETT sizes used in adults. Results. The experimental results demonstrated that the streamlined components improved delivery through the circuit by factors ranging from 1.3-1.5 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 rate 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 flow rates.