The clinical manifestations of CF reflect the progressive derangements to 
the airways (Boat et al., 1989). Early in the disease there is cough, 
together with respiratory tract infection. The sputum becomes thick and 
purulent. There is a long period of chronic bronchitis with acute exacerba- 
tions. Eventually, the permanent derangements of the respiratory tract 
cause symptoms of shortness of breath. The cycles of chronic and acute 
infection eventually culminate in limitation of activity, weight loss, and 
end-stage lung disease with hypoxemia, pulmonary hypertension, cor pulmona- 
le and death (Boat et al., 1989; Shwachman and Kulczycki, 1958). Even with 
aggressive treatment to control infection, clear the airways of secretions, 
and improve nutrition, the 1991 survival data for CF in the USA demon- 
strates that only 50% survive beyond the age of 29 (Patient registry data, 
Cystic Fibrosis Foundation) . 
1.3 Current Therapy for the Respiratory Manifestations of Cystic Fibrosis 
Current therapy for the lung disease in cystic fibrosis requires a multi- 
disciplinary approach of outpatient and inpatient care. Outpatient therapy 
includes frequent postural drainage and chest percussion, administration of 
antibiotics, and bronchodilators . While these therapies are used by most 
clinicians caring for patients with CF, the therapy often varies in differ- 
ent centers. For example, while most clinicians agree regarding the bene- 
fits of postural drainage and chest percussion, some advocate it for all 
patients while others reserve it for those with copious sputum production. 
Likewise, some centers advocate continuous antibiotic therapy while others 
reserve antibiotics for documented infections. Bronchodilator therapy may 
give symptomatic relief to many individuals with CF but the response is not 
universal. Use of other therapeutic strategies such as mucolytics , expec- 
torants and chronic corticosteroids or other anti-inflammatory agents 
remain unproven. Early vaccination for measles and pertussis is important 
and yearly influenza vaccination is advocated. 
Inpatient therapy is necessary when there are exacerbations of pulmonary 
infections or complications of CF lung disease such as hemoptysis, pneumo- 
thorax, respiratory failure, pulmonary hypertension, and cor pulmonale. For 
acute infections requiring hospitalization, empiric antibiotic therapy is 
necessary at first but is then based on culture and sensitivity results 
from respiratory secretions . Patients with acute infections are also given 
increased postural drainage and chest percussion, bronchodilator therapy, 
and occasionally corticosteroids. The treatment of the lung complications 
of cystic fibrosis does not differ from the treatment of other chronic lung 
disease states. 
1.4 New Therapies Being Evaluated for the Respiratory Manifestations of 
Cystic Fibrosis 
New strategies to treat cystic fibrosis include aerosol therapy with recom- 
binant human DNase (to cleave DNA in purulent respiratory secretory, thus 
helping to clear the airways of the thick, infected mucus), aerosolized 
plasma al- antitrypsin or recombinant human secretory leukoprotease inhibi- 
tor (to inhibit neutrophil elastase on the respiratory epithelial surface, 
Recombinant DNA Research, Volume 16 
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