Nebulisers in General Practice

A nebuliser is a device that converts liquid into aerosol droplets suitable for inhalation.¹ Nebulisers use oxygen, compressed air or ultrasonic power to break up medication solutions² and deliver a therapeutic dose of aerosol particles directly to the lungs.³ The use of nebulisers in the community is declining.⁴ However they may still be useful in certain clinical situations, and are preferred by some patients.

Nebulisers can be driven by compressed gas (jet nebuliser) or by an ultrasonically vibrating crystal (ultrasonic nebuliser).⁴ In order to produce small enough particles from solution in 5-10 minutes, gas flow rates of at least 6 l/min are usually necessary. Ultrasonic nebulisers use a rapidly vibrating piezoelectric crystal to produce aerosol particles. Ultrasonic nebuliser machines are often smaller and quieter.⁵ Air jet nebulisers are most frequently used but ultrasonic nebulisers are becoming more common.¹

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.³

Facemasks and mouthpieces are equally effective for administration of aerosol particles but breathless patients may prefer 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.¹

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.³ The 2008 British Guideline on the management of asthma identifies a limited use for nebulisers in this condition.⁶

Asthma⁶

The 2008 British Guideline no longer recommends nebulised therapy for the majority of asthma care. It 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 better pattern of deposition
• Problems of poor inhaler technique 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) is 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/min.

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.⁷

Chronic obstructive pulmonary disease

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.⁸ However there is no actual evidence of superiority of nebulisers over metered-dose inhalers for delivery of bronchodilator therapy in COPD.²

NICE recommend that when using nebulisers in COPD the following should be considered:¹

• Consider a nebuliser for patients with distressing or disabling breathlessness despite maximal therapy with inhalers.
• Assess the patient and/or carer's ability to use the nebuliser before prescribing, and arrange access to equipment, servicing, advice and support.
• Allow the patient to choose whether to use a facemask or mouthpiece, unless taking a drug (such as an anticholinergic drug) where a mouthpiece is required.
• Continue nebuliser treatment only if there is a reduction in symptoms, or an improvement in activities of daily living, exercise capacity or lung function.

A study of domiciliary nebuliser treatment found that compliance was good and patients generally perceive it to provide good symptom control and allow 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 well-being and potential health cost savings.⁹ 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 instructions¹⁰ and technical support, which can be provided by nurse-led domiciliary services.¹¹

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.¹² Regular nebulised anti-pseudomonal treatment also improves lung function and reduces the frequency of exacerbations of infection in people with cystic fibrosis.¹³

Long-term nebulised antibiotics are also useful in bronchiectasis, when other methods of delivery have been unsuccessful.¹⁴ Nebulised antibiotic therapy should be combined with regular postural drainage and courses of oral or intravenous antibiotics for acute exacerbations.¹⁵

Nebulised pentamidine is occasionally used in the specialist prevention or treatment of Pneumocystis pneumonia (PCP). Regular treatment is effective against mild PCP and intermittent inhalation of nebulised pentamidine is effective prophylaxis against infection.¹⁶

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.^17,18

A patient's ability to correctly use equipment must be assessed before recommending nebulised therapy. The actual nebulisers and compressors are not prescribable on the NHS⁴ although they can be bought VAT-free. It is important to select a nebuliser chamber and compressor that are compatible.⁵ Access to equipment, servicing, advice and support must also be organised.¹

Cleaning

• 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.

Maintenance

• 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.

Breakdown

• 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.⁵