AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Development of Controlled Condensational Growth for Aerosol Delivery During Nasal High Flow Therapy
GENG TIAN, Yoen-Ju Son, Michael Hindle, Worth Longest, Virginia Commonwealth University
Abstract Number: 137 Working Group: Health Related Aerosols
Abstract Non-invasive ventilation methods including high flow therapy (HFT) through a nasal cannula interface are becoming increasingly popular as a way to provide breathing support and help move patients off of endotracheal tubes faster. However, an effective method to deliver pharmaceutical aerosols to patients receiving HFT is not currently available. The objective of this study is to quantify performance of controlled condensational growth for pulmonary aerosol drug delivery during HFT considering the effects of a realistic nasal cannula interface, transient inhalation, and the inclusion of hygroscopic excipients. Controlled condensational growth during HFT is a newly proposed strategy in which submicrometer aerosols are delivered to one nostril and warm air saturated with water vapor is delivered to the other nostril. The small particle size allows the aerosol to easily penetrate the delivery lines, cannula, and narrow nasal passages. Aerosol size increase due to condensation and hygroscopic growth beginning in the nasopharynx and continuing into the lungs result in micrometer-size droplets (2-4 micrometers) that will deposit by impaction and sedimentation within the lower airways. In vitro experiments with a characteristic nasal airway model extending through the trachea are used to evaluate transport and deposition of hygroscopic and non-hygroscopic aerosols. Computational fluid dynamics simulations are validated based on the in vitro experiments and used to explore local drug deposition as a result of including the nasal cannula and transient inhalation. Including a hygroscopic excipient to enhance and better control the final particle size is also explored. Results indicate very low nasal depositional losses, the need for on-demand aerosol generation during inhalation, and aerosol growth to 2 micrometers and above within the trachea. Ultimately, the proposed technology will provide a highly effective method for delivering pharmaceutical aerosols to patients, for local or systemic therapy, without interruption of their ventilatory support.