Comparison of ambient and spray aerosol deposition in a standard induction port and more realistic mouth–throat geometry

Longest, P. Worth; Hindle, Michael; Choudhuri, Suparna Das; Xi, Jinxiang

doi:10.1016/j.jaerosci.2008.03.008

Cited by 108 publications

(82 citation statements)

References 44 publications

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“…Considering aerosol transport, the LRN j-x model was previously shown to accurately predict particle transport and deposition for both monodisperse and polydisperse aerosol distributions in airway models and delivery devices on a regional and highly localized basis. (35)(36)(37)(38) Computational grids of the airflow passages were constructed based on previously established best practices. (39,40) The resulting meshes representing the wye connectors with ETTs for the CM and SL designs contained approximately 774,000 and 829,000 cells, respectively.…”

Section: Cfd Simulationsmentioning

confidence: 99%

Optimal Delivery of Aerosols to Infants During Mechanical Ventilation

Longest

Azimi

Hindle

2014

Journal of Aerosol Medicine and Pulmonary Drug Delivery

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Purpose: The objective of this study was to determine optimal aerosol delivery conditions for a full-term (3.6 kg) infant receiving invasive mechanical ventilation by evaluating the effects of aerosol particle size, a new wye connector, and timing of aerosol delivery. Methods: In vitro experiments used a vibrating mesh nebulizer and evaluated drug deposition fraction and emitted dose through ventilation circuits containing either a commercial (CM) or new streamlined (SL) wye connector and 3-mm endotracheal tube (ETT) for aerosols with mass median aerodynamic diameters of 880 nm, 1.78 lm, and 4.9 lm. The aerosol was released into the circuit either over the full inhalation cycle (T1 delivery) or over the first half of inhalation (T2 delivery). Validated computational fluid dynamics (CFD) simulations and whole-lung model predictions were used to assess lung deposition and exhaled dose during cyclic ventilation. Results:In vitro experiments at a steady-state tracheal flow rate of 5 L/min resulted in 80-90% transmission of the 880-nm and 1.78-lm aerosols from the ETT. Based on CFD simulations with cyclic ventilation, the SL wye design reduced depositional losses in the wye by a factor of approximately 2-4 and improved lung delivery efficiencies by a factor of approximately 2 compared with the CM device. Delivery of the aerosol over the first half of the inspiratory cycle (T2) reduced exhaled dose from the ventilation circuit by a factor of 4 compared with T1 delivery. Optimal lung deposition was achieved with the SL wye connector and T2 delivery, resulting in 45% and 60% lung deposition for optimal polydisperse (*1.78 lm) and monodisperse (*2.5 lm) particle sizes, respectively. Conclusions: Optimization of selected factors and use of a new SL wye connector can substantially increase the lung delivery efficiency of medical aerosols to infants from current values of < 1-10% to a range of 45-60%.

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Section: Cfd Simulationsmentioning

confidence: 99%

Optimal Delivery of Aerosols to Infants During Mechanical Ventilation

Longest

Azimi

Hindle

2014

Journal of Aerosol Medicine and Pulmonary Drug Delivery

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“…5). The reduction in the velocity gradient was expected to cause an increase in the turbulent viscosity associated with the downstream propagation to the connection tube of the preseparator [20]. It means that those air recirculation zones were observed at the center of the preseparator, above the orifice, and it was predominant after exiting the orifice.…”

Section: Streamline Field Conditions Of the Preseparator And Whole Camentioning

confidence: 99%

The Comparison of Fluid Dynamics Parameters in an Andersen Cascade Impactor Equipped With and Without a Preseparator

et al. 2014

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Abstract. The fluid dynamic data in Andersen cascade impactor (ACI) are still lacking. Airflows and those affected parameters can be predicted in a preseparator and Andersen cascade impactor (ACI) by computational modeling. This study developed a validated computational fluid dynamic (CFD) model of an ACI and investigated the effects of the preseparator on the CFD parameters. Validation of the computational nozzle velocity for each of the stage 0 to stage 5 of the ACI stages was found to be within a 3.56% error. The flow field indicated that the preseparator accelerated the airflow velocity at the induction tube from 1.13 to 3.71±0.09 m/s and 2.40 to 8.68±0.16 m/s (at 28.3 and 60 L/min of flow rate, respectively). The preseparator produced a nozzle's wall shear stress ranged from 0.08 to 0.34 Pa on a collection plate, while the ex-preseparator spread wall shear from the plate's center was in a range of 0.11 to 0.37 Pa (at 28.3 L/min of flow rate). Moreover, the nozzle velocities increased along the distance from the middle of the collection plate to the periphery. The CFD explained the airflow of the preseparator equipped model by accelerating the airflow along the inlet port to maximize the trapping of desirable particles and the generation of a smooth wall shear stress at the collection plate to reduce the particle reentrainment. While, the ex-preseparator generated an airflow that resulted in a higher wall shear stress occurring on the lower stages.

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“…Considering aerosol transport, the low Reynolds number k-model was previously shown to accurately predict particle transport and deposition for both monodisperse and polydisperse aerosol distributions in airway models and delivery devices on a regional and highly localized basis. [16][17][18][19] Computational grids of the air-flow passages were constructed based on previously established best practices. 20,21 The resulting meshes representing the Y-connectors with ETTs for the commercial and SL designs (see Fig.…”

Section: Cfd Simulationsmentioning

confidence: 99%

Improving Aerosol Drug Delivery During Invasive Mechanical Ventilation With Redesigned Components

Pw¹,

Azimi

Golshahi

et al. 2013

Respir Care

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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.

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Comparison of ambient and spray aerosol deposition in a standard induction port and more realistic mouth–throat geometry

Cited by 108 publications

References 44 publications

Optimal Delivery of Aerosols to Infants During Mechanical Ventilation

Optimal Delivery of Aerosols to Infants During Mechanical Ventilation

The Comparison of Fluid Dynamics Parameters in an Andersen Cascade Impactor Equipped With and Without a Preseparator

Improving Aerosol Drug Delivery During Invasive Mechanical Ventilation With Redesigned Components

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