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Inhaled hyperosmolar agents for bronchiectasis

  • Review
  • Intervention


  • P Wills,

  • M Greenstone

Dr Peter Wills, Consultant Physician, Dept of Respiratory Medicine, Hillingdon Hospital, Pield Heath Road, Uxbridge, Middlesex, UB8 3NN, UK.



Mucus retention in the lungs is a prominent feature of bronchiectasis. The stagnant mucus becomes chronically colonised with bacteria, which elicit a host neutrophilic response. This fails to eliminate the bacteria, and the large concentration of host-derived protease may contribute to the airway damage. The sensation of retained mucus is itself a cause of suffering, and the failure to maintain airway sterility probably contributes to the frequent respiratory infections experienced by many patients.

Hypertonic saline inhalation is known to accelerate tracheobronchial clearance in many conditions, probably by inducing a liquid flux into the airway surface, which alters mucus rheology in a way favourable to mucociliary clearance. Inhaled dry powder mannitol has a similar effect. Such agents are an attractive approach to the problem of mucostasis, and deserve further clinical evaluation.


To determine whether inhaled hyperosmolar substances are efficacious in the treatment of bronchiectasis

Search strategy

MEDLINE and Cochrane databases were searched, and leaders in the field contacted. Searches were current as of October 2004.

Selection criteria

Any trial using hyperosmolar inhalation in patients with bronchiectasis not caused by cystic fibrosis.

Data collection and analysis

Two reviewers assessed studies for suitability.

Main results

One randomised study recruiting 11 participants was included in the review. The outcome measure was tracheobronchial clearance of a particulate radio aerosol after inhalation of dry mannitol on a single occasion, with appropriate control. Airway clearance doubled in the central and intermediate regions of the lung, but not in the peripheral region, after mannitol administration. No side effects were observed, but two patients were premedicated with nedocromil to prevent bronchospasm. Findings from two other non-randomised studies indicated that a single-dose administration of mannitol led to short term improvement in mucociliary clearance, and showed that less mucus retention was still observable 24 hours after dosing in one study. In a third study of mannitol administered once daily over 12 days (open label) an improvement in health status persisted for 7 days after cessation of treatment.

Authors' conclusions

Dry powder mannitol has been shown to improve tracheobronchial clearance in bronchiectasis, as well as cystic fibrosis, asthmatics, and normal subjects. It is not yet available for clinical use. Hypertonic saline has not been specifically tested in bronchiectasis, but improves clearance in these other conditions and in chronic bronchitis. Longer term randomised controlled studies of mannitol and hypertonic saline with clinical endpoints are now needed.

Plain language summary

Plain language summary

Inhalation of dry powder mannitol and of hypertonic saline solution can help clear lung secretions in cases of bronchiectasis; more research is needed on the effects of long term administration.

Bronchiectasis is a lung condition that usually develops after a series of lung problems (such as childhood infections, problems in the lung structure, tuberculosis, and cystic fibrosis). A lot of mucus collects in the lungs, causing discomfort and the need to cough it up. The mucus also collects bacteria, and causes infections and other lung and breathing problems. Inhaling hypertonic saline liquids may help clear this mucus, as may the drug mannitol (inhaled in dry powder form). The review of trials found some evidence that mannitol may help. More research is needed.