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Updated: Jul 2, 2026
Methodology for Sputum Induction and Laboratory Processing
Published on: December 17, 2017
Physical and transport properties of sputum from children with idiopathic bronchiectasis
Gregory J Redding1, Chikako Kishioka2, Patricia Martinez3
1Children's Hospital & Regional Medical Center, Seattle, WA.
Insights
Childhood idiopathic bronchiectasis (IB) sputum exhibits significantly different physical properties, including enhanced cough transportability, compared to cystic fibrosis (CF) and chronic bronchitis (CB) sputum. These findings suggest cough-focused therapies may effectively clear airway mucus in children with IB.
Area of Science:
- Pulmonary Medicine
- Pediatric Respiratory Health
- Mucus Biophysics
Background:
- Childhood idiopathic bronchiectasis (IB) is a prevalent respiratory condition, particularly in indigenous populations, often unrelated to cystic fibrosis (CF) or immunodeficiency.
- The physical and transport properties of sputum in children with IB have not been well-characterized, limiting targeted therapeutic strategies.
- Understanding these properties is crucial for developing effective airway clearance techniques for pediatric IB patients.
Purpose of the Study:
- To investigate and compare the physical and transport properties of sputum in children with idiopathic bronchiectasis (IB).
- To evaluate how these properties differ from those found in children with cystic fibrosis (CF) and adults with chronic bronchitis (CB).
- To identify potential therapeutic implications based on observed sputum characteristics.
Main Methods:
- Sputum samples were collected from children with stable IB and chronic productive cough.
- Key physical properties including viscosity, elasticity, cohesivity, and adhesivity were measured.
- In vitro analysis assessed mucociliary and cough transportability, with comparisons to existing data from CF and CB patient cohorts.
Main Results:
- Sputum from children with IB showed significantly lower elasticity (12-20%) and viscosity (23-32%) compared to CF and CB.
- Surface frictional adhesion was markedly reduced in IB sputum (55% of CF/CB values).
- Cough transportability was substantially improved in IB sputum (43-54% greater than CF/CB), while mucociliary transportability was similar across all groups.
Conclusions:
- Sputum from children with IB possesses distinct physical and transport properties, notably enhanced cough clearance.
- Therapeutic strategies emphasizing cough effectiveness may be sufficient for airway mucus clearance in pediatric IB.
- These unique sputum characteristics may contribute to the differential clinical progression observed between pediatric IB and CF.
Background:
Childhood idiopathic bronchiectasis (IB) unrelated to cystic fibrosis (CF) or known immunodeficiency remains a common problem among indigenous populations in developed and developing countries. The physical and transport properties of sputum among children with IB have not been described, and these properties may suggest therapies that would be particularly effective for this group of children.
Methods:
Sputum from children in stable condition with IB and chronic daily productive cough was collected to measure viscosity, elasticity, cohesivity, adhesivity, and mucociliary and cough transportability in vitro. The results were compared to banked data from the sputa of children with CF and adults with chronic bronchitis (CB) measured by the same methods.
Results:
Sputa from children with CF and adults with CB had similar values for viscosity, elasticity, frictional adhesion, cough transportability, and mucociliary transportability. The elasticity of sputum from children with IB was 12 to 20%, respectively, of the value of CB and CF sputum (p < 0.01). The viscosity of sputum from children with IB was 23 to 32%, respectively, of the value of CB and CF sputum (p < 0.02). The surface frictional adhesion for sputum from children with IB was 55% of the values from both CF and CB sputa (p < 0.0001). Cough transportability for sputum from children with IB was 43 to 54% greater, respectively, than that for sputum from CB and CF patients (p < 0.0001). Mucociliary transportability was similar for all three groups (p > 0.05).
Conclusions:
The physical and transport properties of sputum from children with IB who are stable in the outpatient setting are substantially different and lead to improved cough transportability compared to sputum from children with CF or adults with CB. Therapies that focus on cough may be sufficient to improve airway mucus clearance in children with IB. Sputum properties may explain in part the different clinical course of children with IB compared to children with CF.
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