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Phasic flow mechanisms of mucus clearance.
1Division of Pulmonary Disease, Mount Sinai Medical Centre, Miami Beach, Fl 33140.
European Journal of Respiratory Diseases. Supplement
|January 1, 1987
Summary
Airway mucus can be cleared by two-phase gas-liquid flow during normal breathing. This mechanism is effective for patients with bronchial hypersecretion, especially with controlled breathing patterns.
Area of Science:
- Pulmonary Physiology
- Respiratory Mechanics
Background:
- Excessive bronchial secretions impede airway clearance.
- Normal tidal breathing involves airflow rates capable of transporting secretions.
Purpose of the Study:
- To investigate the efficacy of two-phase gas-liquid flow in clearing bronchial secretions.
- To determine the conditions under which this mechanism is effective during normal breathing.
Main Methods:
- Analysis of two-phase gas-liquid flow dynamics in airways.
- Assessment of secretion transport speed relative to airflow rates.
- Evaluation of secretion properties (thickness, viscosity, elasticity).
Main Results:
- Two-phase gas-liquid flow effectively transports bronchial secretions at normal tidal breathing rates.
- Secretion thickness of approximately 10% of airway diameter facilitates this flow.
- Periodic airflow and higher expiratory than inspiratory velocity enhance secretion transport towards the larynx.
- Increased secretion elasticity and decreased viscosity promote higher transport rates.
- Effective conditions for this flow are met in the 8th to 9th airway generations.
Conclusions:
- Two-phase gas-liquid flow is a significant mechanism for airway mucus clearance, even during normal breathing.
- Controlled breathing techniques, like huffing, leverage this mechanism for improved secretion removal in conditions of bronchial hypersecretion.