Cystic fibrosis hypersecretion

The rate of removal of mucus from the airways is determined by such factors as mucus viscosity, the amount of mucus produced, and the degree of ciliary activity. These processes may be influenced by a variety of diseases, including asthma, cystic fibrosis, and chronic bronchitis [82,83], In patients suffering from cystic fibrosis or chronic bronchitis, mucus hypersecretion is evident and mucociliary function is impaired. The failure to clear mucus from the airways leads to airway obstruction and to chronic colonization of the airways with bacterial organisms (which leads to lung infections and airway inflammation and damage). In asthmatic subjects, airway mucus is more viscous and ciliary transport mechanisms are inhibited [82,83]. In these diseases, the therapeutic objective is to improve mucus clearance from the airways. For example, aerosols of water or saline (especially hypertonic saline) promote clearance of mucus by... 

The primary alteration of the respiratory tract of patients with cystic fibrosis is the hypersecretion of mucus. It is not known whether the mucus is normal or contains excessive amounts of electrolytes. In any case, the mucus secretion is not properly evacuated. It first occludes the smaller bronchi. If the occlusion is incomplete, the alveoli become distended, the inspired air cannot be expired, and emphysematous blebs develop. If the obstruction is complete, atelectasis occurs. The changes in the bronchi and the pulmonary parenchyma favor infection, especially by staphylococci. Pulmonary abscesses, bronchial pneumonia, bronchitis, and pneumonia develop in fact, children with cystic fibrosis often die from respiratory infection. Pneumothorax, hemoptysis, and emphysema are rare complications of the pulmonary disturbance observed in cystic fibrosis (see Fig. 4-46). 

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