Table 6.

Recommendations on the use of trans-nasal aerosol pulmonary delivery

Techniques for aerosol delivery with HFNC	Recommendations	Evidence resource
Aerosol generator	VMN is more efficient than jet nebulizer when placed in-line with HFNC	In vitro pediatric [33, 38] In vivo adult [11, 41]
Discontinue HFNC treatment to deliver conventional aerosol treatment	Not recommended.	Adult in vivo [9, 10, 12] Pediatric in vivo [16, 18] In vitro pediatric [33, 37, 38] In vitro adult [32].
Use conventional aerosol device with concurrent HFNC	Not recommended.	Adult in vitro [32] Pediatric in vitro [34]
Nebulizer placement	VMN should be placed at the inlet of humidifier, except when gas flow is extremely low, such as ≤ 0.25 L/kg/min for infants	Pediatric in vitro [25, 30] Adult in vitro [26, 39]
Gas flow setting during trans-nasal aerosol delivery	If possible, titrate HFNC gas flow below the patient’s inspiratory flow	Pediatric in vivo [38, 40] Adult in vivo [42] Pediatric in vitro [23, 33, 38] Adult in vitro [26, 27, 44].
Open mouth breathing during trans-nasal aerosol delivery	When gas flow exceeds patient inspiratory flow, open mouth breathing reduces inhaled dose; when gas flow is below the patient’s inspiratory flow, open mouth breathing could generate higher inhaled dose.	Adult in vitro [26] Pediatric in vitro [37]
Use heliox to deliver aerosol via HFNC	Might be considered for pediatric patients	Adult in vitro study [27] Pediatric in vitro [23]
Use dry gas to deliver aerosol via HFNC	Not recommended	adult in vivo [42]
Using frequent unit doses or infusion pump to deliver continuous albuterol for asthma exacerbation	If possible, use unit dose to deliver albuterol and decrease gas flow during nebulization; return flow to original setting when nebulization is completed. Titrate FIO2 to maintain SpO2 during the periods of flow reduction. If infusion pump has to be used, relative low gas flow and a higher nominal dose could be considered.	Pediatric in vitro [37]
Stable COPD	Standard dose (2.5 mg) of albuterol is sufficient to elicit bronchodilation responses with HFNC gas flow set at 15–20 L/min.	Adult in vivo [9, 10, 12]
COPD exacerbation	Standard dose (2.5 mg) of albuterol as a starting dose with HFNC flow set at 20–30 L/min is recommended during trans-nasal aerosol delivery.	Adult in vivo [9, 10, 12]
Pulmonary hypertension without hypoxemia	HFNC flow set at 5–10 L/min is recommended	Adult in vivo [15]
Pulmonary hypertension with refractory hypoxemia	Titrating HFNC flow at bedside based on patient’s response in order to determine the optimal flow for each individual patient is recommended	Adult in vivo [15]

HFNC high-flow nasal cannula, VMN vibrating mesh nebulizer, F_IO₂ fraction of inspired oxygen, SpO₂ peripheral capillary oxygen saturation, COPD chronic obstructive pulmonary disease