• Infant tolerance of inhalation of hypertonic saline [ Time Frame: 100 minutes ] [ Designated as safety issue: No ]
  
• The immediate effect of HS on lung function in infants with CF, as measured by differences in expiratory flows before and after inhalation of hypertonic saline [ Time Frame: 100 minutes ] [ Designated as safety issue: No ]
  

• The usefulness of inhalation of hypertonic saline as a technique to obtain secretions from the lower respiratory tract for microbiological diagnosis [ Time Frame: 100 minutes ] [ Designated as safety issue: No ]
  

Cystic fibrosis lung disease is characterized by mucous retention which favors secondary bacterial infection and inflammation, which leads to lung damage and ultimately respiratory failure. Classically, therapeutic interventions are aimed to improve mucociliary clearance, to reduce both bacterial load and lower airway inflammation.

Hypertonic saline (HS) has been used for the induction of sputum production in all age groups to obtain secretions from the lower respiratory for diagnostic purposes. Hypertonic saline is also used in older children with CF, who do not produce sputum spontaneously, to obtain representative samples for microbiology.

There is evidence from studies in patients with cystic fibrosis that HS can improve mucociliary clearance. The improvement was more impressive in areas that were well ventilated, making it likely that HS will work better in patients with relatively preserved pulmonary function. Newer evidence also suggests that the osmotic effect on the airway surface that was expected to be short lived, may actually persist for longer time periods (up to 8 hours). All these data indicate that HS may be a useful agent in the treatment of CF patients.

As the effect on mucociliary clearance was found to be better in areas with adequate ventilation, it is logical to assume that treatment with HS may be most efficacious when initiated early in the disease process. So far, no data on the tolerability of inhalation of HS are available for infants with cystic fibrosis. However, evidence from infants with AIDS as well as recent studies in infants with bronchiolitis suggest that hypertonic saline can be safely administered by inhalation in infants. Nevertheless, proof of tolerability in CF infants is a prerequisite for longer term studies of HS in this age group. In older children, tolerability has been tested by measuring pulmonary function both before and after inhalation of HS saline. Similar data are not yet available for infants.