Rheological analysis of sputum from patients with chronic bronchial diseases.

Bronchial diseases are characterised by the weak efficiency of mucus transport through the lower airways, leading in some cases to the muco-obstruction of bronchi. It has been hypothesised that this loss of clearance results from alterations in the mucus rheology, which are reflected in sputum samples collected from patients, making sputum rheology a possible biophysical marker of these diseases and their evolution. However, previous rheological studies have focused on quasi-static viscoelastic (linear storage and loss moduli) properties only, which are not representative of the mucus mobilisation within the respiratory tract. In this paper, we extend this approach further, by analysing both quasi-static and some dynamic (flow point) properties, to assess their usability and relative performance in characterising several chronic bronchial diseases (asthma, chronic obstructive pulmonary disease, and cystic fibrosis) and distinguishing them from healthy subjects. We demonstrate that pathologies influence substantially the linear and flow properties. Linear moduli are weakly condition-specific and even though the corresponding ranges overlap, distinct levels can be identified. This directly relates to the specific mucus structure in each case. In contrast, the flow point is found to strongly increase in muco-obstructive diseases, which may reflect the complete failure of mucociliary clearance causing episodic obstructions. These results suggest that the analysis of quasi-static and dynamic regimes in sputum rheology is in fact useful as these regimes provide complementary markers of chronic bronchial diseases.

Hyaluronic acid gel based on CPM® technology with and without lidocaine: Is there a difference?

BACKGROUND: In 2011, a cohesive polydensified matrix (CPM® ) hyaluronic acid (HA) gel filler was approved by the USA Food and Drug Administration. In 2014, lidocaine was added to the gel during its manufacturing process. OBJECTIVES: To compare the behavior and rheological properties of a CPM® HA gel with and without lidocaine. METHODS: In our office, we performed simple tests to document the cohesiveness and resistance to traction force of both gels. In two different laboratories, the rheological properties of both gels were measured. We used comparative data of the gel without lidocaine collected from over 6 years. We also observed the gels' behavior when injected into the superficial and mid-reticular dermis, comparing their distribution using both ultrasonography and histology. RESULTS: Over more than 10 years, we observed no difference between both gels, even if clinically we felt a difference in the gels' viscosity upon injection. Their behaviors during injection were similar. Using more sophisticated tests measuring the gels' rheological properties with different techniques, namely sheer sweeps, a difference was, however, noted between the two gels. CONCLUSIONS: Adding lidocaine to CPM® HA gel renders it more viscous. Whether this means a difference in the clinical results, however, would require a comparative clinical study over an extended time period.