increased residual volume to total lung capacity ratio. This is due to increased airways 
resistance, an abnormality that is present early in the disease. Hyperaeration is often manifested 
on the chest x-rays of newborn infants with cystic fibrosis. Obstruction to airways produces a 
typical pulmonary function pattern of airflow obstruction with reduced FEV l5 reduced peak flow 
rate, and reduced forced expiratory flow from 25-75% vital capacity. Later in the disease, the 
carbon monoxide diffusion capacity decreases and is a reliable indicator of impaired pulmonary 
function. 
Eventually, the lung disease of CF leads to hypoxemia from intrapul monary shunting. 
Hypoxemia leads to increased pulmonary vascular resistance, pulmonary hypertension, and cor 
pulmonale. Ninety-five percent of CF patients will eventually die from cor pulmonale 
complicating severe pulmonary hypertension secondary to progressive, generalized derangement 
of the pulmonary architecture (Wood et.al., 1976). The prognosis for life expectancy in cystic 
fibrosis has been improving, and the latest data from 1991 show a median survival of 29.4 years 
(Cystic Fibrosis Patient Registry, 1991: Annual Data Report). 
1.2 Lung Disease in Cystic Fibrosis: The lung disease of cystic fibrosis starts early in life, 
and most infants already have symptoms at the time of diagnosis (Allan et.al., 1980). There 
appears to be a generalized dysfunction of small airways early in life which is probably the 
result of defective hydration of secretions, possibly made worse by the increased susceptibility 
to infection. Some infants with cystic fibrosis develop severe obstructive airways disease, 
requiring mechanical ventilation (Garland et.al., 1989). 
In addition to small airways obstruction from abnormal secretions, cystic fibrosis patients 
also have an increased susceptibility to lower respiratory infection, especially with the gram 
negative organism Pseudomonas aeruginosa . The combination of abnormal secretions and 
infection lead to a necrotizing bronchitis and bronchiolitis with destruction of airway walls, 
bronchiectasis, and eventually respiratory failure. Inflammation is a major component of this 
airways disease. There is a profound pulmonary neutrophilia and neutrophil products such as 
elastase, cathepsin G, and eicosanoids contribute to the inflammation (Berger, 1991). Very high 
concentrations of interleukin- 1 and interleukin-8 have been found in alveolar surface liquid and 
appear to contribute to the recruitment of neutrophils to the lung (Wilmott et.al., 1990; 
McElvaney et.al., 1992). Initial pulmonary infections in cystic fibrosis are usually with 
Staphylococcus aureus . Hemophilus influenzae . E. coli . and klebsiella infections also occur. 
Inevitably, patients become colonized with Pseudomonas aeruginosa , especially the mucoid strain 
of Pseudomonas aeruginosa . In some studies, such colonization is associated with poorer 
survival than in patients not colonized (Wilmott et.al., 1985; Pamela B. Davis, Cystic Fibrosis 
Foundation Consensus Conference: Clinical Outcomes for Evaluation of New Cystic Fibrosis 
Therapies, 1992). 
1.3 Present Medical Treatment of Cystic Fibrosis: The treatment can be broken into two 
main areas: treatment of the gastrointestinal disease and treatment of the pulmonary disease. 
Treatment of the gastrointestinal disease is based on supplements of pancreatic enzymes, 
supplementation with fat-soluble vitamins, and a high-calorie diet. In patients where weight is 
not optimum, in spite of this nutritional therapy, enteral feedings may be used via gastrostomy, 
nasogastric tube, or jej unostomy. In general, the nutritional problems are easier to manage than 
the progressive pulmonary disease. In patients with advanced pulmonary disease, nutritional 
status often becomes poor due to repeated infections, poor appetite, and cachexia. 
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