What are the indications where its use would be superior?
Let us peep into the background of the pathophysiology of the respiratory tract to understand this …
Viruses – influenza, parainfluenza, measles, varicella-zoster, respiratory syncytial virus (RSV). Common, often self limiting but can be complicated
Respiratory tract defences
Mucociliary clearance mechanisms
Mucosal immune system
The Lungs: Function Lung Clearance What do the Lungs do? Exchange of gases How do they do it? Mucus Clearance Effect of Disease Retention Adverse Effects Diagnosis Treatment
Closer understanding based on Burri & Weibel 1973
Closer understanding The cilia on the right side are damaged as occurs in chronic bronchitis, giving rise to decreased clearance of the mucus secretions and difficulty in expectoration Bronchial Epithelium (seen in cross-section) This is what cilia look like ??? Or like this ???
Interaction of cilia and mucus Knowles and Boucher, J Clin Invest, 2002: 109: 571-7 Tarran et al. J Gen Physiol 2001: 118: 223-36 Mucus transport - as seen by time-lapse photos in cell culture experiments
Mucus clearance & retention
Mucus Clearance is dependent on Mucociliary function & Cough reflex,
Clearance from whole Lung and Tracheobronchial would be different
Dependence on Deposition Distribution
Mucus composition with relation to Salt and Water or temperature makes a difference
Medication / Physiotherapy effect outcomes
Mucus clearance & retention Pavia 1985
Mucus retention in chronic bronchitis Pavia 1985
Drugs that increase and aid clearance of respiratory tract secretions
Hypoviscosity agents (Wetting agents)
95% water, 2% glycoproteins
Gel layer-high viscosity from goblet cells
Sol layer – low viscosity from submucosal bronchial glands
Both goblet cells and bronchial sub-mucosal glands increase secretion when irritated.
Vagal stimulation will also increase bronchial sub-mucosal gland secretion.