1 Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University , Richmond, VA.
J Aerosol Med Pulm Drug Deliv. 2014 Oct;27(5):371-85. doi: 10.1089/jamp.2013.1077. Epub 2013 Dec 3.
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.
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 μm, and 4.9 μm. 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.
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-μm 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 μm) and monodisperse (∼2.5 μm) particle sizes, respectively.
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%.
本研究旨在通过评估气溶胶粒径、新型 Y 型连接器以及气溶胶输送时间对接受有创机械通气的足月（3.6kg）婴儿的影响，确定其最佳气溶胶输送条件。
采用振动网孔式雾化器进行体外实验，通过含有商业（CM）或新型流线型（SL）Y 型连接器以及 3mm 气管内导管（ETT）的通气回路，评估质量中值空气动力学直径为 880nm、1.78μm 和 4.9μm 的气溶胶的药物沉积分数和发射剂量。气溶胶在整个吸气周期（T1 输送）或吸气周期的前半部分（T2 输送）输送到回路中。使用经验证的计算流体动力学（CFD）模拟和全肺模型预测来评估在循环通气过程中肺沉积和呼出剂量。
在稳定的气管流量为 5L/min 的情况下，880nm 和 1.78-μm 气溶胶的 80%-90%从 ETT 中传输。基于循环通气的 CFD 模拟，与 CM 设备相比，SL Y 型设计使 Y 型连接器中的沉积损失降低了约 2-4 倍，肺输送效率提高了约 2 倍。与 T1 输送相比，在吸气周期的前半部分（T2）输送气溶胶可使通气回路中的呼出剂量降低 4 倍。与 CM 设备相比，使用 SL Y 型连接器和 T2 输送可实现最佳肺沉积，优化的多分散性（约 1.78μm）和单分散性（约 2.5μm）气溶胶的最佳肺沉积分别为 45%和 60%。
优化选定因素并使用新型 SL Y 型连接器可将婴儿接受的医疗气溶胶的肺输送效率从目前的<1-10%提高到 45-60%的范围。
