Respiratory system2 of 3
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Airway clearance and treatment of infection
Management of the respiratory system in CF is centred on preventing airway obstruction by improving mucociliary clearance, preventing and treating bacterial infection of the airway.1,3 Since CF lung disease is also associated with increased levels of inflammation, anti-inflammatory strategies are used.
The clearance of thick mucus from the lung can be achieved by the approaches detailed below.
Mucolytic agents thin the sputum, enabling more efficient mucociliary transport and the clearance of mucus from the airway. Several therapies are available:2,4
- Dornase alfa — a solution of recombinant human deoxyribonuclease (rhDNase), an enzyme that cleaves excessive DNA found in CF sputum, that reduces viscoelasticity. Dornase alfa has been shown to improve lung function in short- and long-term clinical trials.5
- Hypertonic saline — meta-analyses have shown that a 3–7% solution of nebulised hypertonic saline improves mucociliary clearance in patients with CF.2,18
- Mannitol inhaled dry powder has been reported as a promising treatment for bronchiectasis19 and chronic CF-related lung disease.20 Similar to hypertonic saline, mannitol creates an osmotic gradient promoting the flow of water into the airway lumen.
Airway clearance techniques such as postural drainage and percussion are used to loosen and expel mucus from the lung.3 Moreover, there is mounting evidence that exercise improves respiratory function in CF4 sufferers.
Antibiotics can be administered through an oral, inhaled or intravenous route; the latter may be relied on more in the case of pulmonary exacerbations. Some physicians recommend continuous anti-staphylococcal antibiotic prophylaxis in young children with CF,10, 11 but this is not uniform practice. Early eradication of Pseudomonas aeruginosa infections is important and can be achieved through nebulised anti-pseudomonal therapy – tobramycin nebuliser solution (TNS), colistimethate sodium (colistin) and aztreonam are routinely used in clinical practice.12
Anti-inflammatory agents have been administered to CF sufferers for many years, the most powerful of which are corticosteroids. Nevertheless, neither oral nor inhaled corticosteroids are recommended for routine use.5 High-dose ibuprofen has been demonstrated as effective in slowing the progression of lung disease and is recommended by the Cystic Fibrosis Foundation;6,7 however, because of its side-effect profile it is not used much. Azithromycin maintenance therapy improves respiratory function, possibly also by dampening inflammation.
Lung transplantation is the last therapeutic option for patients with CF who have end-stage lung disease. In Europe, adults are usually referred for transplantation when the FEV1 plateaus at less than 30% of the predicted value and when the patient has a poor quality of life. Nevertheless, age, sex, lung infection and bacteria colonisation will all affect transplant eligibility.14