Worth Longest P, Hindle Michael, Das Choudhuri Suparna
Department of Mechanical Engineering, Virginia Commonwealth University, Richmond, Virginia, USA.
J Aerosol Med Pulm Drug Deliv. 2009 Jun;22(2):67-83. doi: 10.1089/jamp.2008.0692.
For most newly developed spray aerosol inhalers, the generation time is a potentially important variable that can be fully controlled. The objective of this study was to determine the effects of spray aerosol generation time on transport and deposition in a standard induction port (IP) and more realistic mouth-throat (MT) geometry.
Capillary aerosol generation (CAG) was selected as a representative system in which spray momentum was expected to significantly impact deposition. Sectional and total depositions in the IP and MT geometries were assessed at a constant CAG flow rate of 25 mg/sec for aerosol generation times of 1, 2, and 4 sec using both in vitro experiments and a previously developed computational fluid dynamics (CFD) model.
Both the in vitro and numerical results indicated that extending the generation time of the spray aerosol, delivered at a constant mass flow rate, significantly reduced deposition in the IP and more realistic MT geometry. Specifically, increasing the generation time of the CAG system from 1 to 4 sec reduced the deposition fraction in the IP and MT geometries by approximately 60 and 33%, respectively. Furthermore, the CFD predictions of deposition fraction were found to be in good agreement with the in vitro results for all times considered in both the IP and MT geometries. The numerical results indicated that the reduction in deposition fraction over time was associated with temporal dissipation of what was termed the spray aerosol "burst effect." Based on these results, increasing the spray aerosol generation time, at a constant mass flow rate, may be an effective strategy for reducing deposition in the standard IP and in more realistic MT geometries.
对于大多数新开发的喷雾气雾剂吸入器而言，产生时间是一个可完全控制的潜在重要变量。本研究的目的是确定喷雾气雾剂产生时间对在标准诱导口（IP）和更符合实际的口咽（MT）几何结构中的传输和沉积的影响。
选择毛细管气雾剂产生（CAG）作为一个代表性系统，其中喷雾动量预计会对沉积产生显著影响。在25毫克/秒的恒定CAG流速下，使用体外实验和先前开发的计算流体动力学（CFD）模型，对气雾剂产生时间为1、2和4秒时在IP和MT几何结构中的局部和总沉积进行评估。
体外和数值结果均表明，在恒定质量流速下延长喷雾气雾剂的产生时间，可显著减少在IP和更符合实际的MT几何结构中的沉积。具体而言，将CAG系统的产生时间从1秒增加到4秒，可使IP和MT几何结构中的沉积分数分别降低约60%和33%。此外，发现CFD对沉积分数的预测与在IP和MT几何结构中所有考虑时间的体外结果高度吻合。数值结果表明，沉积分数随时间的降低与所谓的喷雾气雾剂“爆发效应”的时间消散有关。基于这些结果，在恒定质量流速下增加喷雾气雾剂的产生时间，可能是减少在标准IP和更符合实际的MT几何结构中沉积的有效策略。
