Administration of aerosol to patients receiving high-flow nasal oxygen (HFNO) ranges from concurrent aerosol delivery by mouthpiece to aerosol via cannula alone. This study examines the conditions to provide optimal aerosol delivery with low- or high-flow nasal oxygen with concurrent mouthpiece or through nasal cannula alone, and the impact on fugitive aerosols.

A vibrating mesh nebuliser delivered salbutamol via mouthpiece, aerosol holding chamber and nasal cannula to an adult head model simulating relaxed breathing. The mean±sd inhaled dose (%) was assayed from a filter distal to the trachea. Optical particle sizers were used to measure fugitive aerosol concentrations during aerosol delivery.

Concurrent low-flow nasal oxygen (LFNO) and aerosol delivery with a mouthpiece and aerosol holding chamber increased the inhaled dose (%) available, 31.44±1.33% when supplemented with 2 L·min^-1 of nasal oxygen. Concurrent HFNO above 30 L·min^-1 resulted in a lower inhaled dose (%) compared to aerosol delivered through HFNO alone. The addition of concurrent LFNO or HFNO resulted in no increase in aerosol levels in the test room.

Concurrent LFNO with a mouthpiece and aerosol holding chamber is an effective and safe means of aerosol delivery.