Impact of saline solution’s nebulisation on the biophysical properties of sputum in bronchiectasis

In bronchiectasis (BE), nebulisation of isotonic saline (IS) and hypertonic agents (hypertonic saline, HS, either alone or combined with hyaluronic acid, HS+HA) on the biophysical properties of sputum has been scarcely studied. This study aimed to compare the changes in biophysical properties of sputum before and after nebulization of IS vs. HS vs. HS+HA in BE patients. <bold>Methods:</bold> This was a post hoc analysis (Herrero-Cortina B, et al. 2018). Sputum samples were spontaneously expectorated and collected both before and after nebulisation. Their complex viscosity (|η*|), storage modulus (Gʹ) and loss modulus (Gʹʹ) were calculated with a RheoStress 1 rheometer (ThermoFisher, MA). Additionally, the solids concentration (%) was determined through a 48-hour freeze-drying process. <bold>Results:</bold> 124 sputum samples were included (Table 1). After nebulization, the HS+HA group presented the most significant change in biophysical properties. HS demonstrated a greater and statistically significant reduction in G’, G’’ and |η*| when comparing before and after nebulization. The HS and HS+HA groups displayed a notable difference in solid reduction, with an enhance decrease in the HS+HA group. <bold>Conclusions:</bold> In patients with BE, nebulising HS solutions appears to induce a greater modification in the biophysical properties of sputum, as well as in solid concentrations when compared to IS. <fig><object-id>erj;64/suppl_68/PA5085/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>