Dataset Information

Rheological effects of hypertonic saline and sodium bicarbonate solutions on cystic fibrosis sputum in vitro.

ABSTRACT:

Background

Cystic fibrosis (CF) is a life-threatening multiorgan genetic disease, particularly affecting the lungs, where recurrent infections are the main cause of reduced life expectancy. In CF, mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein impair transepithelial electrolyte and water transport, resulting in airway dehydration, and a thickening of the mucus associated with abnormal viscoelastic properties. Our aim was to develop a rheological method to assess the effects of hypertonic saline (NaCl) and NaHCO₃ on CF sputum viscoelasticity in vitro, and to identify the critical steps in sample preparation and in the rheological measurements.

Methods

Sputum samples were mixed with hypertonic salt solutions in vitro in a ratio of either 10:4 or 10:1. Distilled water was applied as a reference treatment. The rheological properties of sputum from CF patients, and the effects of these in vitro treatments, were studied with a rheometer at constant frequency and strain, followed by frequency sweep tests, where storage modulus (G'), loss modulus (G″) and loss factor were determined.

Results

We identified three distinct categories of sputum: (i) highly elastic (G' > 100,000 Pa), (ii) elastic (100,000 Pa > G' > 1000 Pa), and (iii) viscoelastic (G' < 1000). At the higher additive ratio (10:4), all of the added solutions were found to significantly reduce the gel strength of the sputum, but the most pronounced changes were observed with NaHCO₃ (p < 0.001). Samples with high elasticity exhibited the greatest changes while, for less elastic samples, a weakening of the gel structure was observed when they were treated with water or NaHCO₃, but not with NaCl. For the viscoelastic samples, the additives did not cause significant changes in the parameters. When the lower additive ratio (10:1) was used, the mean values of the rheological parameters usually decreased, but the changes were not statistically significant.

Conclusion

Based on the rheological properties of the initial sputum samples, we can predict with some confidence the treatment efficacy of each of the alternative additives. The marked differences between the three categories suggest that it is advisable to evaluate each sample individually using a rheological approach such as that described here.

SUBMITTER: Budai-Szucs M

PROVIDER: S-EPMC8276516 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Inhaled hypertonic saline (HS) is an attractive agent for chronic maintenance therapy in infants and toddlers with cystic fibrosis (CF) because it improves defective mucociliary clearance. Prior to undertaking a clinical trial of HS efficacy in young children with CF, tolerability, adherence, and safety must be established.Three-center, open label evaluation of the short-term tolerability, adherence, and safety of 7% HS administered twice daily for 14 days in children with CF 12-30 months of age. The primary objective was to evaluate the proportion of participants unable to tolerate single and repeated doses of 7% HS according to protocol-defined criteria. Participants inhaled a test dose of HS at the enrollment visit; test dose intolerance was defined as fulfillment of at least one of 4 criteria. Participants who tolerated the test dose inhaled 7% HS twice daily for 14±2 days.Twenty children were enrolled. One was withdrawn due to maternal concern over fussiness with application of the facemask for the test dose. Of the 19 participants administered the test dose, 1 was withdrawn due to test dose intolerance (5%, 95% confidence interval 0, 26%). Eighteen participants completed the study; 1 was intolerant (95% CI 0, 27%) at the final visit due to new wheezes on exam in association with an upper respiratory infection and otitis media. Home symptom diaries demonstrated cough as the main symptom in the hour following inhalation, which decreased in frequency over the study period. Adherence as assessed by daily home diary and returned study drug ampoules was high. Participants reported receiving both treatments on a median of 100% of days; a median of 25 ampoules were used during a median of 13 days.7% HS appears well tolerated for up to 14 days in infants and toddlers with CF, with high adherence. These results provide encouraging short-term tolerability and adherence data for future trials assessing the safety and efficacy of 7% HS in young children with CF.