A nebuliser is a device that converts liquid into aerosol droplets suitable for inhalation. Nebulisers use oxygen, compressed air or ultrasonic power to break up medication solutions and deliver a therapeutic dose of aerosol particles directly to the lungs. The use of nebulisers in the community is declining, but they may still be useful in certain clinical situations, and are preferred by some patients.
A wide variety of nebulisers are available. Nebulisers can be driven by compressed gas (jet nebuliser) or by an ultrasonically vibrating crystal (ultrasonic nebuliser). Conventional jet nebulisers waste a great deal of the drug during expiration and ultrasonic nebulisers are becoming more common.
In order to produce small enough particles from solution in 5-10 minutes, gas flow rates of at least 6 L/minute are usually necessary. Ultrasonic nebulisers use a rapidly vibrating piezoelectric crystal to produce aerosol particles. Ultrasonic nebuliser machines are often smaller and quieter. Adaptive aerosol delivering devices release a precise dose that is tailored to the individual's breathing pattern.
Nebulisers are highly inefficient and many deliver only 10% of the prescribed drug dose to the lungs. Much of the drug is caught on the internal apparatus or wasted during exhalation. The efficiency of drug delivery depends on the type and volume of nebuliser chamber and the flow rate at which it is driven. Some chambers have reservoir and valve systems to increase efficiency of particle delivery during inspiration and reduce environmental losses during expiration. Breath-assisted open vent systems improve drug delivery but are dependent on the patient having an adequate expiratory flow.
Facemasks and mouthpieces are equally effective for administration of aerosol particles but breathless patients may prefer facemasks. Both nebulisers and spacers used for small children employ facemasks. Facemasks should be avoided or sealed very tightly when anticholinergic drugs are administered to patients with glaucoma. Facemasks should ideally also be avoided for delivery of nebulised corticosteroids, to prevent contact with the surrounding facial skin and eyes.
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Use of nebulisers in various clinical conditions
Nebulisers are used for emergency and domiciliary treatment of many respiratory diseases. Indications for nebuliser use include the management of exacerbations and long-term treatment of chronic obstructive pulmonary disease (COPD), management of cystic fibrosis, bronchiectasis, HIV/AIDS and symptomatic relief in palliative care. The British Guideline produced jointly by the British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network (SIGN) on the management of asthma identifies a limited use for nebulisers in this condition.
See also the separate article Which Device in Asthma.
Nebulisers are no longer recommended as first-line treatment for acute asthma. The British BTS/SIGN Guideline states that there is insufficient evidence to make recommendations about the use of nebulisers in the emergency situation but does recommend their use in severe asthma attacks. The Guideline cites evidence suggesting that a spacer and metered dose inhaler (MDI) combination can be as effective, if not more effective, in many situations in which nebulisers were formally used. This includes both acute and stable asthma. A spacer plus MDI is to be preferred because of the following issues:
- More effective treatment with fewer side-effects because of a better pattern of deposition
- Problems of poor inhaler technique are largely overcome but spacers need to be used properly too.
- Easily used by children and the elderly (except those with weak or arthritic hands).
- As effective as a nebuliser in treatment of acute attacks but light, cheap, maintenance free, portable and available on prescription.
- Useful for treatment of first attacks of wheezing in patients who have not used inhalers before.
- Useful for administration of bronchodilator when testing reversibility in the surgery to establish the diagnosis of asthma.
- Reduced prescribing costs by basing treatment on the much cheaper metered-dose inhalers.
There are few cases in which the British Guideline recommends nebuliser use. It initially states that there are insufficient data to make a recommendation about their use in life-threatening asthma. However, later the Guideline does recommend that the nebulised route (oxygen-driven) be used for the delivery of high-dose beta agonists in acute asthma with life-threatening features. Nebulisers have, however, certainly been used in this situation to deliver high-dose inhaled drugs. If a nebuliser is used in the emergency situation, there are theoretical risks of oxygen desaturation whilst using air-driven compressors. Therefore, nebulisers should be oxygen-driven with a 'high flow regulator' fitted to the cylinder in order to provide the necessary flow rate of 6 L/minute.
Nebulisers are less useful for domiciliary management of stable asthma, but patient preference should be taken into account, and some patients - especially those with brittle asthma - may have more confidence in nebulisers than in MDIs. Such patients require a verbal and written plan for self-treatment and it is essential that repeated use of the nebuliser does not lead to failure to seek medical help and the prompt use of steroids.
Although patients with COPD are considered to have irreversible bronchoconstriction, most show some reversibility with high-dose bronchodilators. The nebulised aqueous vapour is also believed to alter mucus viscosity and assist expectoration. Therefore, air-driven nebulisers are used frequently in the treatment of acute exacerbations and maintenance of COPD. However, there is no actual evidence of superiority of nebulisers over metered-dose inhalers for delivery of bronchodilator therapy in COPD.
The National Institute for Health and Clinical Excellence (NICE) recommends that when using nebulisers in COPD the following should be considered:
- Hand-held devices are usually best, with a spacer if appropriate.
- Consider a nebuliser for people with distressing or disabling breathlessness despite maximum therapy with inhalers.
- Assess the individual and/or carer's ability to use the nebuliser before prescribing and arrange appropriate support and maintenance of equipment.
- Allow the patient to choose either a facemask or mouthpiece where possible.
- Continue nebuliser treatment only if there is an improvement in symptoms, daily living activities, exercise capacity or lung function.
- Cognitive function and praxis are more important than age in determining the ability of an older patient to use hand-held inhalers or nebulisers.
- Patients experiencing difficulties using hand-held inhalers may also have difficulty using nebulisers.
- Nebulised therapy should not continue to be prescribed without assessing and confirming that one or more of the following occurs:
- A reduction in symptoms.
- An increase in the ability to undertake activities of daily living.
- An increase in exercise capacity.
- An improvement in lung function.
- Nebulised therapy should not be prescribed without an assessment of the patient's and/or carer's ability to use it.
- Patients should be offered a choice between a facemask and a mouthpiece to administer their nebulised therapy, unless the drug specifically requires a mouthpiece (for example, anticholinergic drugs).
- Both nebulisers and hand-held inhalers can be used to administer inhaled therapy during exacerbations of COPD.
- If a patient is hypercapnic or acidotic the nebuliser should be driven by compressed air, not oxygen (to avoid worsening hypercapnia). If oxygen therapy is needed it should be administered simultaneously by nasal cannulae. The driving gas for nebulised therapy should always be specified in the prescription.
A study of domiciliary nebuliser treatment found that compliance was good and patients generally perceive it as providing good symptom control and allowing them to be less dependent on carers or health professionals. The study concludes that nebulisers are helpful in managing chronic lung disease in the community with benefit to patient wellbeing and potential health cost savings.
However, it has also been shown that patients poorly understand the principles of nebuliser treatment and are unaware when compressors frequently malfunction. Patients benefit greatly from improved nebuliser education, written instructions and technical support, which can be provided by nurse-led domiciliary services.
Cystic fibrosis, bronchiectasis, AIDS-associated infections and terminal disease
Nebulisers are used to deliver bronchodilators, corticosteroids and recombinant DNase (rhDNase) to the lungs of patients with cystic fibrosis.
- Bronchodilator therapy not only improves airway obstruction but also increases mucociliary clearance of viscous secretions.
- High-dose corticosteroids are used to minimise airway inflammation in the treatment of bronchial hyperactivity and to reduce the rate of decline of respiratory function.
- rhDNase 1 reduces the viscosity of sputum in cystic fibrosis by digesting DNA of extracellular neutrophils, which is present in huge quantities due to chronic epithelial inflammation. Patients should use specified nebuliser systems to ensure optimal delivery of rhDNase.
- Regular nebulised antipseudomonal treatment also improves lung function and reduces the frequency of exacerbations of infection in people with cystic fibrosis.
Long-term nebulised antibiotics are also useful in bronchiectasis, when other methods of delivery have been unsuccessful. Nebulised antibiotic therapy should be combined with regular postural drainage and courses of oral or intravenous antibiotics for acute exacerbations.
Nebulised pentamidine is occasionally used in the specialist prevention or treatment of pneumocystic pneumonia (PCP). Regular treatment is effective against mild PCP and intermittent inhalation of nebulised pentamidine is effective prophylaxis against infection.
Many nebulised drugs are employed in palliative care but few indications are based on published evidence. However, regular nebulised normal saline helps to loosen tenacious secretions, may reduce breathlessness and is unlikely to do harm. There is also anecdotal evidence to support the use of nebulised opioids in patients with dyspnoea related to cancer and but this has not been supported in clinical trials.
A patient's ability to use equipment correctly must be assessed before recommending nebulised therapy. The actual nebulisers and compressors are not prescribable on the NHS although they can be bought VAT-free. It is important to select a nebuliser chamber and a compressor which are compatible. Access to equipment, servicing, advice and support must also be organised.
- Nebulisers should be cleaned daily in regular usage and after each use in intermittent use.
- The mask, mouthpiece and chamber should be disconnected, disassembled and washed in a warm detergent and water solution. The components should be left to dry overnight.
- Before reuse, the nebuliser should be run for a few seconds before adding medications.
- Disposable components such as the mouthpiece, mask, tubing and nebuliser chamber should be changed every 3 to 4 months.
- Compressors require annual servicing by manufacturer or local service provider.
- Patients must have a written plan describing whom to contact in the case of emergency, such as a respiratory or practice nurse.
- If nebuliser times are slow, the equipment should be cleaned and treatment tried again. If it remains slow, a spare nebuliser should be used.
- Patients must be advised to self-treat, such as with multiple doses of a handheld device, and to ask for medical help.
Further reading & references
- Chronic obstructive pulmonary disease, NICE Clinical Guideline (June 2010)
- Brocklebank D, Ram F, Wright J, et al; Comparison of the effectiveness of inhaler devices in asthma and chronic obstructive airways disease: a systematic review of the literature. Health Technol Assess. 2001;5(26):1-149.
- No authors listed; Current best practice for nebuliser treatment. The Nebulizer Project Group of the British Thoracic Society Standards of Care Committee. Thorax. 1997 Apr;52 Suppl 2:S1-3.
- Rees J; Methods of delivering drugs. BMJ. 2005 Sep 3;331(7515):504-6.
- No authors listed; Nebulizer therapy. Guidelines. British Thoracic Society Nebulizer Project Group. Thorax. 1997 Apr;52 Suppl 2:S4-24.
- De Benedictis FM, Selvaggio D; Use of inhaler devices in pediatric asthma. Paediatr Drugs. 2003;5(9):629-38.
- British Guideline on the Management of Asthma; British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network - SIGN, 2008 (latest revision May 2011)
- Ward MJ; Nebulisers for asthma. Thorax. 1997 Apr;52 Suppl 2:S45-8.
- O'Driscoll BR; O'Driscoll BR; Nebulisers for chronic obstructive pulmonary disease. Thorax. 1997 Apr;52 Suppl 2:S49-52.
- Barta SK, Crawford A, Roberts CM; Survey of patients' views of domiciliary nebuliser treatment for chronic lung disease. Respir Med. 2002 Jun;96(6):375-81.
- Boyter AC, Carter R; How do patients use their nebuliser in the community? Respir Med. 2005 Nov;99(11):1413-7. Epub 2005 Apr 21.
- Godden DJ, Robertson A, Currie N, et al; Domiciliary nebuliser therapy--a valuable option in chronic asthma and chronic obstructive pulmonary disease? Scott Med J. 1998 Apr;43(2):48-51.
- Conway SP, Watson A; Nebulised bronchodilators, corticosteroids, and rhDNase in adult patients with cystic fibrosis. Thorax. 1997 Apr;52 Suppl 2:S64-8.
- Ryan G, Mukhopadhyay S, Singh M; Nebulised anti-pseudomonal antibiotics for cystic fibrosis. Cochrane Database Syst Rev. 2000;(2):CD001021.
- Steinfort DP, Steinfort C; Effect of long-term nebulized colistin on lung function and quality of life in patients with chronic bronchial sepsis. Intern Med J. 2007 Jul;37(7):495-8.
- Currie DC; Nebulisers for bronchiectasis. Thorax. 1997 Apr;52 Suppl 2:S72-4.
- McIvor RA, Berger P, Pack LL, et al; An effectiveness community-based clinical trial of Respirgard II and Fisoneb nebulizers for Pneumocystis carinii prophylaxis with aerosol pentamidine in HIV-infected individuals. Toronto Aerosol Pentamidine Study (TAPS) Group. Chest. 1996 Jul;110(1):141-6.
- How your doctor can help with breathlessness, CancerHelp UK
- Ahmedzai S, Davis C; Nebulised drugs in palliative care. Thorax. 1997 Apr;52 Suppl 2:S75-7.
- The Care and Use of Nebulisers, The Cardiothoracic Centre – Liverpool 2008
|Original Author: Dr Laurence Knott||Current Version: Dr Colin Tidy||Peer Reviewer: Dr Hayley Willacy|
|Last Checked: 19/01/2012||Document ID: 498 Version: 4||© EMIS|
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