Table 6 Recommendations on the use of trans-nasal aerosol pulmonary delivery

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 F_IO₂ 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]