In-vitro pressure analysis in nasal high flow therapy for infants

Background: Nasal high flow therapy (NHF) increases the airway pressure and induces wash-out. Both effects however are are very difficult to assess in-vivo. Objective: We aim at obtaining detailed information about airway pressure and wash-out from experiments with 3D-printed airway tracts of infants. Methods: The 3D-printed geometries are retrieved from the SAINT model, and provided with 37 pressure holes along the airway tract. A range of flow rates and cannula sizes is used to obtain a relation between flow rate, pressure, and wash-out. Results: Three 3D-printed models have been obtained, see Fig. 1. A consistent relation between flow rate and pressure difference over the device including various cannula sizes has been established, see Fig. 2, and complete pressure-profiles along the upper airway tract were obtained, also see Fig. 2. Conclusions: At end-inspiration or end-expiration the pressure along the airway tract from the nasal cavity downward is approximately constant. This also indicates that wash-out is limited to the nasal cavity region.