Tracheal pressure generated by high-flow nasal cannula in 3D-Printed pediatric airway models

Objective: Heated and humidified high flow nasal cannula (HFNC) is an increasingly used form of noninvasive respiratory support with the potential to generate significant tracheal pressure. The aim of this study was to quantify the pressure generated by HFNC within the trachea in anatomically correct, pediatric airway models. Methods: 3D-printed upper airway models of a preterm neonate, term neonate, toddler, and small child were connected to a spontaneous breathing computerized lung model at age-appropriate ventilation settings. Two commercially available HFNC systems were applied to each airway model at increasing flows and the positive end-expiratory pressure (PEEP) was recorded at the level of the trachea. Results: Increasing HFNC flow produced a quadratically curved increase in tracheal pressure in closed-mouth models. The maximum flow tested in each model generated a tracheal pressure of 7 cm H₂O in the preterm neonate, 10 cm H₂O in the term neonate, 9 cm H₂O in the toddler, and 24 cm H₂O in the small child. Tracheal pressure decreased by at least 50% in open-mouth models. Conclusions: HFNC was found to demonstrate a predictable flow-pressure relationship that achieved sufficient distending pressure to consider treatment of pediatric obstructive sleep apnea and tracheomalacia in the closed-mouth models tested.