Association between the viscoelastic characteristics and sputum colour in patients with bronchiectasis

<b>Introduction:</b> In patients with non-cystic fibrosis bronchiectasis (NCFB), classifying sputum according to the colour can estimate the presence of infection and/or inflammation. The aim of the study was to identify if there’s an association between viscoelastic characteristics and sputum color in patients with NCFB. <b>Methods:</b> Cross-sectional observational study in patients with NCFB. The sputum colour&nbsp;was classified according Murray9s scale. Viscoelastic characteristics were measured with a rheometer (HAAKE MARS III), with a plate-plate spindle diameter of 35mm and gap of 0.4mm under 37°C. The mean of the storage modulus (elasticity, Gʹ) and loss modulus (viscosity, Gʹʹ) were measured and the magnitude of the complex modulus (stiffness, |G*|) and phase angle (δ) were calculated. <b>Results:</b> We enrolled 64 samples from 64 NCFB&nbsp;patients (Fig.1A). Purulent samples showed significantly higher values in comparison to mucoid and mucopurulent groups, whereas deformation was significantly lower.&nbsp;Moreover, the viscosity dynamic assessment regarding to applied shear stress showed that purulent samples viscosity remained the highest all along (Fig.1B). <b>Conclusions:</b> Purulent samples showed a greater storage modulus, loss modulus and viscosity compared with mucoid or mucopurulent ones.&nbsp;The sputum colour is a validated and easy assessment with&nbsp;significant association with viscoelastic characteristics.