The influence of changing interfaces on aerosol delivery within high flow oxygen setting in adults: An in-vitro study

Abstract

Despite the fact that the nasal-cannula is more comfortable than facemask, using facemask with high flow oxygen therapy (HFOT) may be beneficial in mouth-breathers. The aim of the present work was to evaluate aerosol-delivery both between different interfaces and flows using HFOT setting.The experiment was conducted using an Aerogen-Solo vibrating mesh nebulizer connected proximally to the humidifier in HFOT circuit using three different interfaces (nasal-cannula, mouthpiece, and valved-facemask) at 10, 20 and 30 L/min oxygen-flows. The amount of drug deposited on each part was quantified using HPLC.Total inhalable dose using facemask and mouthpiece (15.3% and 13.7% of nominal-dose, respectively) was significantly higher (p < 0.001) than that delivered by nasal-cannula (6.5% of nominal-dose) at oxygen-flow 10 L/min. Aerosol-delivery was decreased with increasing oxygen-flow regardless of the interface used. Aerosol-deposition within the interface increased significantly with increasing gas flow in nasal-cannula only. The mean inhaled-dose delivered without oxygen was 11.1, 7.4 and 1.3% of nominal-dose by valved-facemask, mouthpiece and nasal-cannula, respectively. Aerosol-deposition in the tubing of nasal-cannula only was significantly (p < 0.001) increased when aerosol nebulization was not combined with oxygen-delivery (88.0% of nominal-dose).Valved-facemask or mouthpiece can serve as an acceptable option in mouth-breathers for HFOT combined with aerosol-delivery. Increasing gas-flow decreased dose-delivered.