Impaired mucociliary clearance

Disruption of these defense mechanisms can lead to bacterial colonization or viral infection. Mucus temperature is important in controlling respiratory infections because decreasing below central body core temperature not only impairs ciliary movement,hut also enhances viral replication,- greatly increasing the likelihood of respiratory infection. Drying of airway mucus also increases the possibility of respiratory infection by reducing mucus thickness and impairing mucociliary clearance, i- i--... 

Multiple factors play a role in the development of AOM. Viral infection of the nasopharynx impairs eustachian tube function and causes mucosal inflammation, impairing mucociliary clearance and promoting bacterial proliferation and infection. Children are predisposed to AOM because their eustachian tubes are shorter, more flaccid, and more horizontal than adults, which make them less functional for drainage and protection of the middle ear from bacterial entry. Clinical signs and symptoms of AOM are the result of host immune response and damage to cells caused by inflammatory mediators such as tumor necrosis factor and interleukins that are released from bacteria.4... 

Viscous middle ear effusions caused by allergy or irritant exposure may contribute to impaired mucociliary clearance and AOM in susceptible individuals.4 OME occurs chronically in atopic children, and effusion can persist for months after an episode of AOM. Children with chronic OME usually require tympanostomy tube placement to reduce complications such as hearing and speech impairment and recurrent otitis media. 

Increased access of irritants Impaired mucociliary clearance Loss of relaxing factors... 

The airway epithehum is also known to be injured by a variety of viral and bacterial products, a number of which have proteolytic activity themselves or which induce cellular injury as a consequence of the host immunological responses that they evoke. Episodes of airflow obstruction are known to accompany such infections and impaired mucociliary clearance is a common feature of certain infections. 

Cystic fibrosis is a hereditary disorder caused by mutation in the cystic fibrosis transmembrane conductance regulator gene that encodes a cyclic adenosine monophosphate-regulated chloride channel. Defects in chloride ion transport in the airway epithelia lead to abnormal airway secretions, impaired mucociliary clearance, chronic bacterial infection, bronchiectasis, and premature death. Delivery of the cystic fibrosis transmembrane conductance regulator cDNA by adenovirus vectors or the plasmid-liposome complex resulted in transient correction of the defects in patients with cystic fibrosis. Formulations of cationic lipid-DNA complexes for aerosol delivery are being explored to improve on the gene therapy approach. 

Normal physiological functioning of the sinuses depends on ostial patency, mucociliary function, and the quantity and quality of secretions. Retention of sinus secretions may result if ostial diameter is compromised if cilia are damaged, impairing mucociliary clearance of secretions or if increased viscosity or volume of secretions exceeds the clearing capacity of the sinus mucociliary drainage system. 

Patients with moderate to severe pulmonary disease requiring vascular access surgery will benefit most from a LRA technique. General anesthesia (GA) with intermittent positive pressure ventilation (IPPV) and use of muscle relaxants impairs respiration more than LRA with maintained spontaneous breathing. IPPV may cause dynamic overinflation or barotrauma to lungs, promote atelectasis and impair mucociliary clearance [7]. This may be associated with increased pulmonary morbidity, prolonged hospital stay, resource utilization and cost. 

The relationship between these defects and the clirrical marrifestations of cystic fibrosis still remains speculative. However, a reasonable hypothesis is that the ion transport defects may lead to suboptimal volttmes of airways surface liquid resulting in impaired mucociliary clearance, bacterial colonization, and... 

Some investigators suggest that an impaired mucociliary clearance and the increased retention of particles in the airways might correlate with the occurrence of lung cancer. Churg and Stevens (59) found an association between particles retained in certain airway walls and the occurrence of lung cancer in these lobes. The bronchial mucosa from the lobe with the cancer contained about three times more mineral particles than the lobe without the cancer. 

The particle size is the most important factor that contributes to the clearance of particles. For particles deposited in the anterior parts of the nose, wiping and blowing are important mechanisms whereas particles on the other areas of the nose are removed with mucus. The cilia move the mucus toward the glottis where the mucus and the particles are swallowed. In the tracheobronchial area, the mucus covering the tracheobronchial tree is moved upward by the cilia beating under the mucus. This mucociliary escalator transports deposited particles and particle-filled macrophages to the pharynx, where they are also swallowed. Mucociliary clearance is rapid in healthy adults and is complete within one to two days for particles in the lower airways. Infection and inflammation due to irritation or allergic reaction can markedly impair this form of clearance. 

Impairment of mucociliary clearance, the rate at which mucus is transported from the nose to the pharynx, was found in a study of 68 Danish hardwood furniture workers. Mucostasis (defined as a nasal transit time of 40 or more minutes) increased in direct proportion to the dust concentration at 25.5mg/m, 63% had mucostasis vs. 11% at 2.2 mg/m. ... 

An impairment of the mucociliary clearance increases the susceptibility against respiratory infectious diseases frequently associated with marginal vitamin A deficiency (Sommer et ah, 1984). Interestingly vitamin A status following supplementation with 15-mg RP monthly for 2.5 months (Rahman et ah, 1996) was not improved in the presence of respiratory tract infections (Sommer et ah, 1986). 

Major determinants of the efficiency of mucociliary clearance are cilia density, periciliary fluid, and composition of mucus. Some drugs and excipients, such as preservatives in drug formulations, may diminish the ciliary movement in the nasal cavity and trachea. A suggested adverse effect of ciliostasis (permanently or momentarily arrest or impairment of ciliary activity) is lower respiratory tract infection as a result of impaired nasal microbiological defense. 

Black, A., Evans, J.C., Hadfield, E.H., Macbeth, R.G., Morgan, A. Walsh, M. (1974) Impairment of nasal mucociliary clearance in woodworkers in the furniture industry. British Journal of Industrial Medicine, 31, 10-17. 

In several disease states, the mucociliary clearance is impaired, and in such subjects the clearance from the tracheobronchial tree almost certainly exceeds 24 hours [33,34], making the concept of alveolar deposition in terms of retention in excess of 24 hours invalid. The slowly cleared material in normal subjects has... 

Neutrophil elastase is implicated in the induction of bronchial disease, causing structural changes in lungs, impairment of mucociliary clearance, and impairment of host defenses. Protease inhibitors, namely, inhibitors of neutrophil elastase, are being investigated currently for the treatment of COPD. 

In normal conditions, secretion production is small and voluntary coughing is unproductive. However, when disease is present (such as in acute bronchitis), the molecular components change, production increases considerably, and sputum is formed from mucus, inflammatory cells, cell debris, and bacteria. Disruption of normal secretion or mucociliary clearance impairs pulmonary function and lung defense and increases risk of infection (14). However, it is not clear whether hypersecretion is only a marker of inflammation or a cause of pathological changes. There is even some evidence that stasis of mucus protects against inhaled material (15). 

Techniques for controlling and assisting the mobilization of secretions from the airways have long been advocated for use in the patient with impairment in mucociliary clearance or an ineffective cough mechanism. The goals of this therapy are to reduee airway obstruction, improve mucociliary clearance and ventilation, and optimize gas exehange. 

---