Inhaled nebulised adrenaline delivery in children and adults: A simulation study

Sometimes, there is an urgent need to administer inhaled adrenaline to children, awake, sedated or anaesthetised to treat asthma, bronchospasm, croup, and suspected laryngeal/pharyngeal oedema or stridor, which can become severe or even life-threatening. To better inform emergency dosing and administration guidelines, we aimed to quantify the amount of adrenaline delivered for inhalation from a nebuliser, in a simulated experimental delivery set-up for spontaneously breathing children and adults, either via an anaesthetic face mask, a Laryngeal Mask Airway (LMA) or an Endotracheal tube (ETT).

Adrenaline was delivered using a jet or vibrating-mesh nebuliser as per standard hospital protocols for each patient's weight: 3, 12, 30 and 75 kg, using age and weight-appropriate LMA, ETT or facemask, and collected on a filter to represent the inhaled dose. Adrenaline was rinsed from the filter and stored at 4 degrees Celsius until quantified using liquid chromatography.

The facemask delivered a smaller inhaled mass percentage (2-10%) compared to an LMA (8-15%) with any patient weight (p < 0.001), and an ETT (12-32%) delivered 2 times more than an LMA (p < 0.001).

The dose delivered using an LMA was approximately four times that of the facemask for infants and young children, and ETT was two times more than LMA. Future research should consider improving the delivery efficiency of nebulised adrenaline via LMA for children of all sizes in appropriate circumstances and investigate improving drug delivery to children via facemask, as well as the safety and efficacy of higher-dosage regimens.