AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
In vitro Aerosol Delivery to the Lungs during Non-Invasive Ventilation High Flow Nasal Therapy
LALEH GOLSHAHI, Worth Longest, Mandana Azimi, Ross Walenga, Michael Hindle, Virginia Commonwealth University
Abstract Number: 701 Working Group: Health Related Aerosols
Abstract Administration of conventional sized aerosols through a nasal cannula during high flow nasal therapy (HFNT) results in high drug depositional losses in the circuit components and extrathoracic airways. Controlled condensational growth techniques employing submicrometer aerosols are evaluated to minimize aerosol losses and maximize drug delivery to the lungs during HFNT. A mixer-heater and an Aeroneb Lab nebulizer were used to generate submicrometer (MMAD=0.9±0.2 micro-meter) aerosols from a 0.2% albuterol sulfate and 0.2% sodium chloride in water formulation. A streamlined cannula was employed with aerosol delivered at 20LPM for the excipient enhanced growth (EEG) technique. A divided and streamlined cannula was employed for enhanced condensational growth (ECG) with aerosol delivered at 20LPM to one nostril and heated and humidified air to the other nostril at 15LPM. The cannula was placed in an adult nose-mouth-throat (NMT) model with a filter at the exit of the trachea and attached to a breath simulator. Aerosol was delivered continuously or intermittently (1s or 2s) synchronized with peak inspiratory flows of 23, 35 and 44LPM, respectively. Aerosol drug deposition in the NMT model and the HFNT components was determined by HPLC. The drug mass collected on the filter was considered as the in vitro lung dose. Losses in the HFNT components were low (<10.6%), and there were low drug deposition losses in the NMT model (<6.6%). Emitted doses were greater than 74% of the nominal dose. Mean (SD) lung doses of 62.5(1.7)%, 73.1(2.3)%, and 74.5(3.3)% were produced using 1-second intermittent EEG aerosol delivery with peak inspiratory flows of 23, 35, and 44LPM, respectively. These were significantly greater than observed using the continuous delivery method (31.63(0.54)%). Respiratory losses were consistently lower during 1s delivery compared to 2s and decreased with increasing inspiratory flow rate. Efficient aerosol delivery of submicrometer aerosols was feasible using the controlled condensational techniques.