Adrenaline Inhalation Under Tracheal Intubation by High-Flow Nasal Cannula for Laryngeal Edema

Postextubation laryngeal edema occasionally causes difficulty in breathing, especially in children due to their small airways or the presence of congenital airway abnormalities, resulting in reintubation or prolonged respiratory control. ¹ Pre-extubation intravenous corticosteroids and postextubation adrenaline nebules are used to prevent and treat laryngeal edema in the intensive care setting. However, patients who underwent pharyngolaryngeal surgery or have laryngitis have a high risk of reintubation due to excessive laryngeal edema. We reported the successful treatment of a high-risk case of laryngeal edema with pre-extubation adrenaline inhalation through high-flow nasal cannula (HFNC). Postextubation, the patient exhibited significant improvement of epiglottic edema.

A 6-year-old girl with laryngomalacia was treated with laser ablation for mucosal swelling of the arytenoid cartilages. Corticosteroids were administered intravenously, and rocuronium was given for 3 days to avoid mechanical irritation to the larynx. On postoperative day 3, epiglottic edema was detected using a laryngeal videoscope (Fig. 1A). The cuff-leak test showed air leakage around the endotracheal tube.

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FIG. 1.

Images of epiglottis taken through a laryngeal videoscope. (A) Before the inhalation of nebulized adrenaline through HFNC. The white arrow indicates swollen epiglottis. (B) After inhalation of nebulized adrenaline through HFNC. The edema of the epiglottis dramatically improved. (C) Postextubation. HFNC, high-flow nasal cannula.

However, she had a high risk for respiratory complications after extubation. Racemic adrenaline nebulization used a vibrating-mesh nebulizer under tracheal intubation to improve the edema and reduce the risk of respiratory difficulties after extubation (Nebulizer: Aerogen solo, Aerogen Ltd. Flow rate 0.3 mL/min, HFNC: Optiflow Jr, Fisher & Paykel Health Care, Nasal Cannula: Optiflow Junior 2, size L). The nebulizer was installed directly downstream of the humidifier in the HFNC circuit (2 L/(kg·min), Air). Then, 0.5 mL of racemic epinephrine (1 mg/mL), diluted with 2 mL of saline, was administrated into the nebulizer chamber.

Pressure support with synchronized intermittent mandatory ventilation was performed, and the ventilator settings were weaned to prepare for extubation. The tracheal tube cuff remained inflated to prevent entry of the atomized adrenaline into the lungs. Although Cuff leak test was not performed after the procedure, the ventilator showed an increased leak rate of 10%–20% from 0% under 20 cmH₂O endotracheal cuff pressure (Ventilator: Puritan Bennett™ 980 series, Medtronic). Edema improved after inhalation, followed by extubation. She exhibited no respiratory symptoms during spontaneous breathing (Fig. 1B, C). The next day, she had no respiratory symptoms and was moved to the general ward.

Inhalation by HFNC under tracheal intubation is challenging because the oral cavity is a dead space. A large volume of continuous flow by HFNC creates air convection from the nasal cavity to the oral cavity, resulting in air purging in the upper airway. ² Effective results with drug inhalation by HFNC have been documented. It delivers a sufficient drug dose to the airways. ³ Moreover, the increased airway pressure and enlarged pharyngeal space, induced by HFNC, allow the nebulized adrenaline to reach the larynx. ⁴ The median particle size, which passes through the pediatric nasal prongs, is ∼1 μm.

These small particles do not deposit in the upper airway under spontaneous breathing. However, the HFNC flow rate was high enough (20 L/min), and inertial impaction was effectively generated even for small particles, resulting in efficient deposition in the larynx. ⁵ Thus, inhalation by HFNC under tracheal intubation is a viable treatment option. It significantly improved the edema of the epiglottis preextubation. This study was limited because a quantitative measurement of the effectiveness of this procedure was not done. Thus, a quantitative method to evaluate laryngeal edema during intubation is needed.

In conclusion, adrenaline inhalation by HFNC under tracheal intubation could give great benefits on improving laryngeal edema.