Dyspnoea (shortness of breath) is described as 'an uncomfortable awareness of breathing'.  It is a subjective symptom which may not correlate with measurable physical abnormalities such as hypoxia. Treating the dominant cause of breathlessness, including the contributing co-morbidities, is likely to be most effective, but is not always possible.
Shortness of breath becomes more frequent in patients as their disease progresses,  is associated with a poorer prognosis,  and is usually multifactorial in patients with advanced disease. The effective assessment and management of dyspnoea is increasingly regarded as an important quality measure in palliative care. 
What is known
Numerous assessment tools for dyspnoea exist, but there is no consensus about which is the appropriate tool for palliative care. 
Evidence supports the use of either oral or parenteral opioids for relieving the symptom of dyspnoea, and most of this evidence relates to morphine. There is no evidence to support the use of nebulised opioids, however. A recent systematic review identified low level evidence for the efficacy of fentanyl for dyspnoea. 
A recent meta-analysis has shown that oxygen does not improve symptoms of dyspnoea in cancer patients who are mildly or non-hypoxaemic, although there may be a sub-population who do experience benefit.  A systematic review found no strong evidence for the benefit of oxygen in patients with dyspnoea and advanced disease from any cause, although the numbers studied were very small. 
The use of nebulised frusemide for dyspnoea has been investigated. A recent systematic review suggests it is a promising approach, although the included studies were small and diverse. 
If drainage of a malignant pleural effusion is required and is clinically appropriate, evidence supports the effectiveness of thoracoscopic talc pleurodesis. There is also low level evidence to support the safety and effectiveness of tunneled pleural catheters in this setting. 
Research from small trials supports non-pharmacological interventions including general support, breathing re-training, activity planning and adaptation strategies, counselling and relaxation. [1,10] These are complex interventions and it is not clear which components in the package may be most effective. Nurse or physiotherapist-led interventions including breathlessness clinics may improve management of dyspnoea in palliative care patients with lung cancer.  For Chronic Obstructive Pulmonary Disease (COPD) patients who are able to participate in pulmonary rehabilitation, there is evidence of a clinically significant benefit in terms of dyspnoea, fatigue and wellbeing  and home-based physiotherapy interventions may also offer benefit. 
Benzodiazepines are frequently prescribed for management of distress associated with dyspnea, but have not been shown to be of benefit. They cause more drowsiness than opioids, and should be used if non-pharmacological methods and opioids have failed to control the symptom. [14,15]
There is limited evidence to support the use of non-invasive ventilation to relieve the experience of dyspnoea in Chronic Obstructive Pulmonary Disease COPD. 
What it means in practice
- Routine assessment of patients for dyspnoea is essential in palliative care, and assessment needs to include a measure both of intensity of the symptom, and of any associated distress or impairment. 
- Opioids are the first line pharmacological management for dyspnoea patients with advanced disease or cancer.
- Oxygen prescription should be individualised, based on a formal assessment of benefit after a therapeutic trial in the individual patient. 
- Non-pharmacological allied health and nursing interventions offer an additional strategy to help patients manage their symptoms. Interventions should be tailored to the individual patient. Those who are very disabled by dyspnoea or close to the end of life may be best cared for with a pharmacological approach.
- Refractory dyspnoea at the end-of-life, which causes severe distress and does not respond to medical management is a challenging problem. Sometimes sedation is required. Guidelines for sedation for refractory symptoms at the end of life have been proposed.