The influence of purulence on ciliary and cough transport in bronchiectasis.

BACKGROUND: Individuals with bronchiectasis exhibit colonization and infection of the respiratory system, with a consequent alteration of the macroscopic appearance of secretions, which ranges from mucoid to purulent. Purulence is related to the structural conformation, rheological profile, and transport indexes of mucus. We analyzed and compared the transport properties of respiratory secretions with mucoid appearance versus those with purulent appearance in patients with bronchiectasis and in subjects without lung disease.
METHODS: In a simulated cough machine we assessed the mucociliary transport and contact angle of 32 mucoid and 19 purulent samples from subjects with bronchiectasis, and 21 samples from subjects without lung disease.
RESULTS: Mucociliary transport was lower in the mucoid samples (0.78 ± 0.22) and in the purulent samples (0.73 ± 0.22) than in the samples from subjects without lung disease (1 ± 0.19). The purulent samples had less displacement in the simulated cough machine (7.57 ± 3 cm) than did the mucoid samples (23 ± 15 cm) or the samples from subjects without lung disease (34 ± 8.4 cm), as did the mucoid samples compared to the samples from subjects without lung disease. The purulent samples had a higher contact angle (25 ± 6.1°) than the mucoid samples (17 ± 7.8°) or the samples from subjects without lung disease (10 ± 2.5°), as did the mucoid samples compared to the samples from subjects without lung disease.
CONCLUSIONS: Respiratory secretions in individuals with bronchiectasis have poor transport properties, which manifest as reduced mucociliary transport, reduced mucus transport by cough, and higher contact angle. These features were more accentuated in the purulent samples. This simple classification can be used by therapists to plan treatments, and by researchers to obtain more homogeneity between groups of subjects.