Placing nebulizers within a HFT circuit upstream from the humidification chamber may enable to deliver clinically relevant masses of aerosol at the cannula outlet, but more importantly downstream of the nose and pharynx, even in case of high patients' inspiratory flow. This method of aerosol therapy is expected to produce a bronchodilatatory effect to be evaluated in the clinical settings.

Aerosol therapy in infants and toddlers is challenging. Nebulization within a nasal high flow (NHF) circuit is attractive. The aim of this study was to quantify aerosol lung deposition when combined with NHF as compared with standard practice. Lung doses were measured scintigraphically after nebulization with jet and mesh nebulizer placed within a NHF circuit in a spontaneously breathing non-human primate model (macaque) and in the anatomical bench SAINT model, respectively representing a full-term newborn and a 9-month-old toddler. In the SAINT model, lung depositions observed with the mesh nebulizer placed in the NHF circuit set at 2 and 4 L/min were 3.3% and 4.2% of the nebulizer charge, respectively, and similar to the 1.70% observed with the control standard facemask jet nebulization (6 L/min flow). In the macaque model, the depositions observed with the mesh nebulizer in the NHF circuit set at 2 and 4 L/min were 0.49% and 0.85%, respectively, also similar to the control measurement (0.71%). Mesh nebulization within a NHF circuit set at 8 L/min and jet nebulization either within a NHF circuit or placed on top of the cannula (NHF set at 2 L/min; total flow of 8 L/min), resulted in a significantly lower lung depositions. Mesh nebulization within a NHF circuit delivering up to 4 L/min gas is likely to be at least as effective than jet nebulization with a facemask in infants and toddlers. Aerosol facemask placement on top of cannulas or jet nebulization within the NHF circuit may be less effective. Pediatr Pulmonol. 2017;52:337-344. © 2016 Wiley Periodicals, Inc.

BackgroundThere is an absence of controlled clinical data showing bronchodilation effectiveness after nebulization via nasal high-flow therapy circuits.ResultsTwenty-five patients with reversible airflow obstruction received, in a randomized order: (1) 2.5 mg albuterol delivered via a jet nebulizer with a facial mask; (2) 2.5 mg albuterol delivered via a vibrating mesh nebulizer placed downstream of a nasal high-flow humidification chamber (30 L/min and 37 °C); and (3) nasal high-flow therapy without nebulization. All three conditions induced significant individual increases in forced expiratory volume in one second (FEV1) compared to baseline. The median change was similar after facial mask nebulization [+ 350 mL (+ 180; + 550); + 18% (+ 8; + 30)] and nasal high flow with nebulization [+ 330 mL (+ 140; + 390); + 16% (+ 5; + 24)], p = 0.11. However, it was significantly lower after nasal high-flow therapy without nebulization [+ 50 mL (− 10; + 220); + 3% (− 1; + 8)], p = 0.0009. FEV1 increases after facial mask and nasal high-flow nebulization as well as residual volume decreases were well correlated (p < 0.0001 and p = 0.01). Both techniques showed good agreement in terms of airflow obstruction reversibility (kappa 0.60).ConclusionAlbuterol vibrating mesh nebulization within a nasal high-flow circuit induces similar bronchodilation to standard facial mask jet nebulization. Beyond pharmacological bronchodilation, nasal high flow by itself may induce small but significant bronchodilation.Electronic supplementary materialThe online version of this article (10.1186/s13613-018-0473-8) contains supplementary material, which is available to authorized users.