Background: Current clinical practice during high-flow nasal therapy (HFNT) involves utilization of a nasal cannula to provide humidification, with a facemask placed over the cannula to deliver aerosol. Few studies have compared aerosol delivery across various delivery interfaces during HFNT. The objective of this study was to address this gap in the literature and evaluate aerosol delivery using two nebulizer types across different drug delivery interfaces, nasal cannula, facemask, and mouthpiece, during simulated adult HFNT.
Methods: A facemask or mouthpiece and/or a nasal cannula were positioned on an anatomically correct adult head model. The head model was connected to a breathing simulator via a collection filter. Both healthy breathing pattern and distressed breathing patterns were utilized. Aerosol dose was determined by quantifying the mass of drug captured on a filter positioned distal to the trachea.
Results: During simulated healthy breathing, a significantly greater aerosol dose was observed when the vibrating mesh nebulizer (VMN) was integrated with HFNT alone, supplying aerosol and humidified air simultaneously (2.88 ± 0.15%), as opposed to using with a facemask (0.33 ± 0.07%, 1.62 ± 0.46%, and 1.07 ± 0.25% at 0 L/min (LPM), 2LPM, and 6LPM, respectively) or mouthpiece (0.56 ± 0.13%, 2.16 ± 0.06%, and 1.82 ± 0.41% at 0LPM, 2LPM, and 6LPM). In addition, aerosol delivery was also significantly greater when the VMN was integrated into simulated HFNT (2.88 ± 0.15%), in comparison with using the jet nebulizer (JN) with a facemask (0.82 ± 0.16%) or a mouthpiece (0.86 ± 0.11%). During simulated distressed breathing, a significantly greater aerosol dose was observed when the VMN was integrated with HFNT, supplying aerosol and humidified air simultaneously (6.81 ± 0.45%), compared with using a facemask (0.86 ± 0.04%, 2.96 ± 0.26%, and 4.23 ± 0.93% at 0LPM, 2LPM, and 6LPM) or mouthpiece (0.73 ± 0.37%, 0.97 ± 0.20%, and 3.11 ± 0.53% at 0LPM, 2LPM, and 6LPM, respectively). Aerosol delivery was also greater when the VMN was integrated into HFNT (6.81 ± 0.45%), in comparison with using the JN with a facemask (5.72 ± 0.71%) or a mouthpiece (0.69 ± 0.53%). Furthermore, across all drug delivery interfaces, and in line with previous reports, aerosol delivery was greater during simulated distressed breathing, in comparison with simulated healthy adult breathing.
Conclusions: This article will be of considerable benefit in enhancing the understanding of aerosol delivery during HFNT, an increasingly adopted therapeutic intervention by healthcare professionals.
Keywords: Aerosol; Aerosol chamber; Facemask; High-flow nasal therapy; Mouthpiece; Nasal cannula; Vibrating mesh nebulizer.