Use of home oxygen therapy in adults
Home oxygen therapy can provide significant health benefits in selected patients with chronic respiratory disease. This article provides a summary of the main types of oxygen therapy and the guidelines for their use.
Selected patients with chronic respiratory disease can benefit from using home oxygen therapy. Patient assessment is key: in the past, home oxygen was frequently provided without adequate assessment, leading to lack of clinical benefit and potentially wasted resources. In 2011, new regional contracts for home oxygen providers were introduced. Since that time, oxygen has been ordered via home oxygen order forms (HOOF) rather than GP prescription. In most areas, patients are assessed for home oxygen by home oxygen assessment and review teams, with primary care only involved for the provision of urgent oxygen on occasion out of hours.
There are five main categories of home oxygen, some of which are more often known by their acronyms (see Table 1). Long-term oxygen therapy (LTOT) has the greatest evidence base, but this is largely drawn from two small and historic randomised controlled trials in chronic obstructive pulmonary disease (COPD) patients.1,2 Evidence in other patient groups is limited and often extrapolated from COPD outcome data.
Table 1. Summary of different types of home oxygen therapy
The British Thoracic Society (BTS) has recently published its first home oxygen guideline,3 which presents available evidence and recommendations for home oxygen use. This review summarises the guideline recommendations relevant to primary care for each type of oxygen alongside practical considerations.
Long-term oxygen therapy
LTOT involves the use of continuous oxygen for at least 15 hours in every 24-hour period, at a flow rate to deliver sufficient oxygenation to achieve SpO2 >92 per cent. There are many misconceptions surrounding LTOT: the health benefits include improved life expectancy (usually after 18 months of use) and a potential (not universal) relief of dyspnoea. Use for up to 24 hours may be of additional benefit.
The two most important studies for LTOT use in COPD patients showed significant benefit and it would now be difficult to randomise patients to a placebo controlled trial without home oxygen. Most of the arterial blood gas, hours of use and patient selection criteria are derived from these studies. 1,2 Interestingly smokers were not excluded, nor their outcomes described separately to nonsmokers. Evidence does not therefore exist that smokers do not achieve the same benefit from LTOT treatment. However, there are serious safety concerns about smoking and fire risk with home oxygen. Smoking should be strongly discouraged. Indeed, many home oxygen teams require patients to have stopped smoking before LTOT assessment and a smoking-specific risk assessment is mandated in the BTS guidelines. The home oxygen provider has a contractual requirement to carry out a risk assessment in the patient’s home. Although this is not mandatory for the fire and rescue service, a community fire safety officer may visit to discuss fire safety, smoke alarms and safe exit routes in the event of a fire.
Patients who will benefit from LTOT treatment are those with stable COPD and a resting PaO2 =7.3kPa or patients with stable COPD with a resting PaO2 =8kPa, with evidence of peripheral oedema, polycythaemia or pulmonary hypertension. Screening oxygen saturation levels for referral for formal assessment are 92 and 94 per cent respectively. The benefits of LTOT are regardless of the level of raised PaCO2 (hypercapnia). Similar criteria for LTOT use are applied to other nonCOPD patient groups with respiratory or cardiac disease such as interstitial lung disease, cystic fibrosis and cardiac failure. Guidelines for selecting patients for referral for LTOT assessment are summarised in Table 2.
Table 2. Guidance for selecting patients for referral for long-term oxygen therapy (LTOT) assessment
Patients with neuromuscular disease or chest wall disorders, eg kyphoscoliosis causing restrictive lung disease, are at risk of developing type 2 respiratory failure and should not be given oxygen therapy without first establishing noninvasive ventilation. The amount of oxygen required needs to be carefully titrated using blood gas monitoring. These patients can be at particular risk if they become acutely unwell with a respiratory tract infection, and referral to an acute admissions unit for blood gas assessment is a priority in these circumstances.
Ambulatory oxygen therapy
Ambulatory oxygen therapy (AOT) involves carrying small portable oxygen cylinders while walking to improve walking distance by minimising breathlessness during exercise and shortening recovery time. Although oxygen cylinders are small, they can still be heavy for some patients to carry, and this is a common reason for patients not to use AOT. However, for selected patients, use of AOT can promote independence outside the home and enable exercise, which is beneficial to respiratory disease outcomes, eg in patients with cystic fibrosis.
A formal assessment should be carried out by home oxygen teams using a graded exercise test such as a shuttle walk test with and without oxygen. Suitable patients for referral are those who are ambulant outside their homes, who desaturate on exercise but in whom exercise capacity is limited by breathlessness with a prolonged or distressing recovery time.
Nocturnal oxygen therapy
Some patients with advanced cardiac failure develop periodic breathing patterns at night. They often wake recurrently due to low oxygen levels and consequently can suffer extreme daytime tiredness. An overnight sleep study or oximetry can detect this problem, and a trial of nocturnal oxygen therapy (NOT), usually given at low flow rates of 1L/min, can improve sleep quality and daytime alertness. There is no evidence to support overnight oxygen therapy alone in other patient groups, eg those with COPD and interstitial lung disease, outside current LTOT recommendations.
Palliative oxygen therapy
Palliative oxygen therapy (POT) can be considered in patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness, or who are hypoxaemic with resting SpO2 less than 92 per cent or who have normal resting oxygen levels but in whom all other approaches have been exhausted. Opioids have been shown in small studies to be more effective than oxygen in both hypoxaemic and nonhypoxaemic patients.4 Other options may be more effective and are outlined in Table 3.
Table 3. Approaches to breathlessness management to be tried before palliative oxygen therapy
If a patient remains distressed despite the above strategies, palliative oxygen can be ordered. Practical considerations regarding assessing response to POT are outlined in Table 4.
Table 4. Guidance for assessing response to palliative oxygen therapy (POT)
Short-burst oxygen therapy
Oxygen administered from large static cylinders used to be the commonest form of home oxygen therapy. Patients would use oxygen for short periods when breathless or for reassurance, hence the name shortburst oxygen therapy (SBOT). However, there is no evidence base to support its use. When funding arrangements for home oxygen changed from a ‘per cylinder’ to ‘daily use’ tariff, SBOT was identified as a significant waste of resources. Many patients, however, remain strongly adherent to the concept of SBOT, and removal of this form of home oxygen can be personally challenging. However, the number of patients now being started on SBOT is dwindling as home oxygen assessment teams become more established and community services offer improved support for respiratory patients following hospital discharge.
Risks of home oxygen therapy
Oxygen is highly flammable and there is increasing recognition and reporting of accidents related to fire in home oxygen patients.5 Risks involve all flammable sources, but the most frequently occurring risk is patients, or other household members, smoking. Patients should undergo smoking cessation counselling and support prior to initiation of home oxygen. For all households, a risk assessment should be carried out to minimise risk, particularly to children and those in multiple occupancy dwellings.
Other risks include trip and fall risks owing to oxygen tubing: these remain the responsibility of the home oxygen supplier who has a contractual duty to carry out a risk assessment.
This article has summarised the indications for use of the five different types of home oxygen therapy and highlighted some practical concerns around assessment and safety issues. More detail on patient assessment and monitoring can be found in the full British Thoracic Guidelines published in 2015.3 The establishment of specialised home oxygen assessment and review teams is key to ensuring correct home oxygen usage. Nevertheless, certain clinical scenarios remain challenging such as the use of oxygen in palliative care, and more research in this area would be welcome so that patients are given the best possible support to address their symptoms.
1. Nocturnal Oxygen Therapy Trial Group. Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease: a clinical trial. Ann Int Med 1980;93(3): 391–8.
2. Long term domiciliary oxygen therapy in chronic hypoxic cor pulmonale complicating chronic bronchitis and emphysema. Report of the Medical Research Council Working Party. Lancet 1981;1(8222):681–6.
3. Hardinge M, et al. BTS Guideline for home oxygen use in adults. BTS Home Oxygen Guideline Development Group on behalf of the British Thoracic Society Standards of Care Committee. Thorax 2015;70:Supplement 1. https://www.brit-thoracic.org.uk/documentlibrary/clinical-information/oxygen/homeoxygen-guideline-(adults)/bts-guidelines-forhome-oxygen-use-in-adults/
4. Abernethy AP, et al. Effect of palliative oxygen versus room air in relief of breathlessness in patients with refractory dyspnoea: a double-blind, randomised controlled trial. Lancet 2010;376(9743):784–93.
5. Centers for Disease Control and Prevention. Fatal fires associated with smoking during long-term oxygen therapy – Maine, Massachusetts, New Hampshire, and Oklahoma, 2000–2007. Morb Mortal Wkly Rep 2008;57(31):852–4.
Declaration of interests
Dr Hardinge has received speaker fees from pharmaceutical companies (GSK, Chiesi, Pfizer, Boehringer) over the past two years. Dr Freeman has received honoraria for speaking from Boehringer Ingelheim, Novartis, AstraZeneca, Almiralland Pfizer; he has also received educational support/grants from Napp and Pfizer. Dr Suntharalingam has received educational support from Bayer, GSK and Actelion, speaker fees from AstraZeneca, Teva, GSK and Actelion and consultancy fees from Boehringer, Bayer and Actelion. Dr Hippolyte has no interests to declare.