Evidence for use of long-term oxygen therapy in patients with chronic obstructive pulmonary disease

• Patients with stable chronic obstructive pulmonary disease (COPD) and a resting PaO₂ ≤7.3 kPa should be assessed for long-term oxygen therapy (LTOT) which offers survival benefit and improves pulmonary haemodynamics. (Grade A)

• LTOT should be ordered for patients with stable COPD with a resting PaO₂ ≤8 kPa with evidence of peripheral oedema, polycythaemia (haematocrit ≥55%) or pulmonary hypertension. (Grade A)

• LTOT should be ordered for patients with resting hypercapnia if they fulfil all other criteria for LTOT. (Grade B)

Evidence for use of LTOT in other respiratory or cardiac disease

• LTOT should be ordered for patients with interstitial lung disease (ILD) with a resting PaO₂ ≤7.3 kPa. (Grade D)

• LTOT should be ordered for patients with ILD with a resting PaO₂ ≤8 kPa in the presence of peripheral oedema, polycythaemia (haematocrit ≥55%) or evidence of pulmonary hypertension. (Grade D)

Good practice point

• Patients with ILD who experience severe breathlessness could be considered for palliative oxygen therapy (POT). (√)

LTOT in patients with cystic fibrosis

• LTOT should be ordered for patients with cystic fibrosis (CF) with a resting PaO₂ ≤7.3 kPa. (Grade D)

• LTOT should be ordered for patients with CF with a resting PaO₂ ≤8 kPa in the presence of peripheral oedema, polycythaemia (haematocrit ≥55%) or evidence of pulmonary hypertension. (Grade D)

LTOT in patients with pulmonary hypertension

• LTOT should be ordered for patients with pulmonary hypertension, including idiopathic pulmonary hypertension, when the PaO₂ is ≤8 kPa. (Grade D)

LTOT in patients with neuromuscular or chest wall disorders

• Non-invasive ventilation (NIV) should be the treatment of choice for patients with chest wall or neuromuscular disease causing type 2 respiratory failure. Additional LTOT may be required in case of hypoxaemia not corrected with NIV. (Grade D)

LTOT in patients with advanced cardiac failure

• LTOT should be ordered for patients with advanced cardiac failure with a resting PaO₂ ≤7.3 kPa. (Grade D)

• LTOT should be ordered for patients with advanced cardiac failure with a resting PaO₂ ≤8 kPa in the presence of peripheral oedema, polycythaemia (haematocrit ≥55%) or evidence of pulmonary hypertension on ECG or echocardiograph. (Grade D)

Outcomes of LTOT in patients who continue to smoke

• If LTOT is ordered for patients who are continuing to smoke, the potential for more limited clinical benefit should be discussed with the patient. (Grade D)

Referral and assessment of patients for LTOT

• Written and verbal information should be given to patients referred to home oxygen assessment services at the time of referral. (Grade D)

• Patients with a resting stable oxygen saturation (SpO₂) of ≤92% should be referred for a blood gas assessment in order to assess eligibility for LTOT. (Grade C)

Good practice point

• In patients with clinical evidence of peripheral oedema, polycythaemia (haematocrit ≥55%) or pulmonary hypertension, referral for LTOT assessment may be considered at SpO₂ levels ≤94% to identify patients with a resting PaO₂ ≤8 kPa. (√)

Referral for home oxygen at hospital discharge

• Patients should undergo formal assessment for LTOT after a period of stability of at least 8 weeks from their last exacerbation. (Grade B)

Good practice points

• Patients who have borderline saturations (ie 93–94%) should have their oxygen saturations monitored at their annual review with their general practitioner (GP) or practice nurse, or sooner if they experience an exacerbation in the interim. (√)

• Patients who exacerbate frequently and are unable to achieve a period of stability lasting 8 weeks may need to be assessed at an earlier stage after exacerbation. If LTOT is ordered for such patients, they should be counselled that in the future LTOT may no longer be required once they achieve a more stable state. (√)

• Patients should not normally have LTOT ordered at the time of an acute exacerbation of their underlying condition. However, if home oxygen is ordered (eg, at hospital discharge), it should be limited to patients with an SpO₂ of ≤92%, who are breathless, and unable to manage off oxygen. These patients should undergo a blood gases assessment and be counselled that in the future LTOT may not be required after formal reassessment. (√)

• The date of the patient's last exacerbation should be included in the referral request to the home oxygen assessment service. (√)

Use of pulse oximetry, arterial and capillary blood gases in assessment for LTOT

• Patients potentially requiring LTOT should not be assessed using pulse oximetry alone. (Grade D)

Assessment using arterial blood gases and capillary blood gases

• Patients being assessed for LTOT should undergo initial assessment for suitability using arterial blood gases (ABG) sampling. (Grade A)

• Patients assessed for LTOT during a period of apparent clinical stability should undergo two ABG measurements at least 3 weeks apart, before the need for LTOT can be confirmed. (Grade B)

• Patients undergoing LTOT assessment should be reassessed with ABG after oxygen titration is complete to determine whether adequate oxygenation has been achieved without precipitating respiratory acidosis and/or worsening hypercapnia. (Grade D)

• For oxygen titration during LTOT assessment, capillary blood gases (CBG) sampling can be used in place of ABG sampling for re-measuring PaCO₂ and pH at different oxygen flow rates. (Grade A)

• For oxygen titration during LTOT assessment, cutaneous capnography can be used in place of ABG sampling for re-measuring PaCO₂ alone but not pH at different oxygen flow rates. (Grade A)

Good practice points

• Patients undergoing a radial ABG should be assessed with an Allen's test first, to ensure they have a dual blood supply to the hand from both radial and ulnar arteries. (√)

• Patients undergoing a radial ABG should be consented for the procedure with a discussion of possible risks. (√)

• In many community commissioned home oxygen service–assessment and review (HOS-AR) services it is not practical for patients to undergo ABG sampling during LTOT assessment. Under such circumstances, a combination of CBGs and oximetry (but not capnography) could be used as an alternative tool for initial assessment for LTOT, and after oxygen titration is complete. Some patients may receive LTOT unnecessarily using this approach, but it is unlikely that any patient would be inappropriately denied LTOT. (√)

Management of hypercapnia during LTOT assessment

• Patients with baseline hypercapnia should be monitored for the development of respiratory acidosis and worsening hypercapnia using ABGs after each titration of flow rate, as well as an ABG after oxygen titration is complete. (Grade D)

Good practice points

• Patients who develop a respiratory acidosis and/or a rise in PaCO₂ of >1 kPa (7.5 mm Hg) during an LTOT assessment may have clinically unstable disease. These patients should undergo further medical optimisation and be reassessed after 4 weeks. (√)

• Patients who develop a respiratory acidosis and/or a rise in PaCO₂ of >1 kPa (7.5 mm Hg) during an LTOT assessment on two repeated occasions, while apparently clinically stable, should only have domiciliary oxygen ordered in conjunction with nocturnal ventilatory support. (√)

LTOT hours of use

• LTOT should be ordered for a minimum of 15 h per day, and up to 24 h per day may be of additional benefit. (Grade C)

LTOT flow rates

• Patients eligible for LTOT should be initiated on a flow rate of 1 L/min and titrated up in 1 L/min increments until SpO₂ >90%. An ABG should then be performed to confirm that a target PaO₂ ≥8 kPa (60 mm Hg) at rest has been achieved. (Grade B)

• Non-hypercapnic patients initiated on LTOT should increase their flow rate by 1 L/min during sleep in the absence of any contraindications. (Grade B)

• Patients initiated on LTOT who are active outdoors should receive an ambulatory oxygen assessment to assess whether their flow rate needs increasing during exercise. (Grade B)

Good practice points

• Ambulatory and nocturnal oximetry may be performed to allow more accurate flow rates to be ordered for exercise and sleep, respectively. (√)

• Patients initiated on LTOT who have cognitive, visual or coordination impairments, may not be able to safely manipulate their own flow rates and should be maintained on a single flow rate. (√)

• Flow rates may be increased at 20 min intervals during an oxygen titration until a target PaO₂ is achieved. (√)

Patient education at time of assessment

• Patients initiated on LTOT should be provided with formal education by a specialist home oxygen assessment team to ensure compliance with therapy. (Grade D)

• Patients being commenced on home oxygen on discharge from hospital should be advised that home oxygen may be removed if reassessment shows clinical improvement. (Grade D)

Follow-up of LTOT patients

• LTOT patients should receive follow-up at 3 months after LTOT has been ordered, which should include assessment of blood gases and flow rate to ensure LTOT is still indicated and therapeutic. (Grade A)

• LTOT patients should receive follow-up visits at 6–12 months after their initial 3-month follow-up, which can be either home based or in combination with hospital visits. (Grade D)

• Follow-up visits should be conducted by a specialist home oxygen assessment team with the necessary skills to deliver patient education and manage withdrawal of home oxygen. (Grade D)

Good practice point

• All patients for whom LTOT has been ordered should be visited at home within 4 weeks by a specialist nurse or healthcare professional with experience of domiciliary oxygen therapy. The visit provides an opportunity to highlight potential risks and should be used to reinforce education and offer support to the patient and carer. Compliance may be checked, along with smoking status, symptoms of hypercapnia and oxygen saturations on oxygen to check that oxygen is therapeutic. (√)

Nocturnal oxygen therapy

• Nocturnal oxygen therapy (NOT) is not recommended in patients with COPD who have nocturnal hypoxaemia but who fail to meet the criteria for LTOT. (Grade A)

Good practice point

• Other causes of nocturnal desaturation in COPD should be considered such as obesity hypoventilation, respiratory muscle weakness or obstructive sleep apnoea (OSA). (√)

NOT in patients with cardiac disease and nocturnal desaturation

• NOT can be ordered for severe heart failure patients who do not fulfil indications for LTOT and have evidence of sleep disordered breathing (SDB) leading to daytime symptoms, after other causes of nocturnal desaturation have been excluded (eg, obesity hypoventilation or OSA) and heart failure treatment has been optimised. Treatment with modalities of ventilatory support should also be considered. (Grade B)

Good practice point

• If NOT is ordered for patients with severe heart failure, it should be ordered at a low flow rate of 1–2 L/min and response should be assessed by a reduction in symptoms of daytime sleepiness, and SDB indices as measured by an overnight oximetry study. A blood gas assessment should be undertaken to exclude worsening hypercapnia and respiratory acidosis. Treatment with modalities of ventilatory support should be considered for patients who are hypercapnic. (√)

NOT in patients with CF

• NOT should not be given to patients with CF with nocturnal hypoxaemia alone who do not fulfil LTOT criteria. It can be considered in patients with evidence of established ventilatory failure, where it should be given with NIV support. (Grade B)

NOT in patients with ILD

• NOT should not be given to patients with ILD with nocturnal hypoxaemia alone, who do not fulfil LTOT criteria. (Grade B)

NOT in patients with neuromuscular weakness

• Patients with neuromuscular weakness affecting respiratory muscles should not have NOT alone ordered. It can be considered in patients with evidence of established ventilatory failure, where it should be given with NIV support. (Grade B)

NOT in patients with OSA, obesity hypoventilation syndrome or overlap syndrome

• Patients with OSA, obesity hypoventilation syndrome (OHS) or overlap syndrome should not have NOT alone ordered. It can be considered in patients with evidence of established ventilatory failure, where it should be given with NIV support. (Grade D)

Ambulatory oxygen therapy

• AOT should not be routinely offered to patients who are not eligible for LTOT. (Grade B)

• AOT should not be routinely offered to patients already on LTOT. (Grade D)

• Ambulatory oxygen therapy (AOT) assessment should only be offered to patients already on LTOT if they are mobile outdoors. (Grade A)

• AOT should be offered to patients for use during exercise in a pulmonary rehabilitation programme or during an exercise programme following a formal assessment demonstrating improvement in exercise endurance. (Grade B)

Good practice points

• Patients started on AOT should be reviewed regularly. If AOT was started during an exacerbation or when unwell, an initial review at 4–6 weeks to check it is still indicated is essential. (√)

• Home visits may be useful to identify problems with equipment or set-up. Further reviews should be carried out every 6 months when stable, or sooner if the patient’s clinical status changes. (√)

• AOT therapy may offer patients with active lifestyles or active treatment regimens (eg, CF) additional benefits. All patients should be assessed for AOT in the context of their daily activity and therapies. (√)

• It is recognised that there may be some patients, for example with ILD and disabling breathlessness, who do not qualify for LTOT but who do desaturate on exercise who may benefit from AOT. Once all other medical interventions have been optimised, these patients could be considered for AOT following formal assessment and continued provision following demonstration of benefit and compliance. (√)

• Patients with high respiratory rates (common in CF and ILD) should receive AOT at a selected flow rate via a Venturi mask, which exceeds their peak tidal and exertional inspiratory flow, and be supplied with home oxygen equipment which is able to deliver the required high flow rates. (√)

• AOT may be offered to LTOT patients who could otherwise not achieve 15 h per day oxygen usage, or who are severely hypoxaemic and are too symptomatic to leave their house without supplemental oxygen but may need to do so, for example to attend their GP or hospital appointments. Formal assessment is not required in these circumstances. (√)

Palliative oxygen therapy

• Patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness should not receive treatment with POT if they are non-hypoxaemic or have mild levels of hypoxaemia above current LTOT thresholds (SpO₂ ≥92%). (Grade A)

• Patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness should receive assessment for a trial of treatment with opiates from an appropriately trained healthcare professional. (Grade A)

• Patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness should receive assessment for a trial of treatment with non-pharmacological treatments including fan therapy from an appropriately trained healthcare professional. (Grade D)

Good practice point

• POT may on occasion be considered by specialist teams for patients with intractable breathlessness unresponsive to all other modalities of treatment. In those instances, individual formal assessment of the effect of palliative oxygen on reducing breathlessness and improving quality of life should be made. (√)

Short burst oxygen therapy

• Short burst oxygen therapy (SBOT) should not be ordered for use prior to or following exercise in hypoxaemic or normoxic patients with COPD. (Grade A)

• SBOT should not be ordered on discharge from hospital for non-hypoxaemic patients with severe COPD. (Grade A)

Use of SBOT in cluster headache

• SBOT delivering high flow oxygen therapy (12 L/min via a non-rebreather mask) should be offered to treat acute attacks of cluster headache (CH). (Grade A)

Good practice point

• Appropriate equipment will need to be provided in order to ensure delivery of high flow rate oxygen at 12 L/min for CH using a non-rebreather mask. Patients will usually have warning of a CH attack, and so provision should be made for urgent 4 h installation of home oxygen, if available, rather than a permanent home supply being provided. (√)

Equipment for home oxygen therapy

• Oxygen concentrators should be used to deliver LTOT at flow rates of 4 L/min or less. (Grade B)

• Portable oxygen should be delivered by whatever mode is best suited to the individual needs of the patient to increase the daily amount of oxygen used and activity levels in mobile patients. (Grade C)

Good practice point

• The type of portable device selected should balance patient factors with cost effectiveness, resources and safety. (√)

Oxygen delivery

• Nasal cannulae should be considered as the first choice of delivery device for patients requiring home oxygen therapy. As an alternative some patients may benefit from or prefer a Venturi mask system. (Grade D)

• Oxygen-conserving devices can be used in home oxygen patients requiring high flow rates to increase the time the cylinder will last. (Grade B)

Good practice points

• Venturi masks should be considered in patients in whom there are concerns about existing or developing hypercapnic respiratory failure, those with a high resting respiratory rate or those with cognitive problems. (√)

• Oxygen-conserving devices should be considered in patients who are active outside the home, following an ambulatory oxygen assessment. (√)

Humidification

• Humidification of home oxygen should not be ordered for non-tracheostomy patients. (Grade D)

Good practice point

• Patients receiving oxygen via a tracheostomy should receive humidified oxygen. (√)

Carrying home oxygen

• Less able patients should be offered wheeled devices or backpacks if assessment shows they improve ambulation and quality of life. (Grade B)

Good practice point

• When being transported in cars, cylinders should be secured either with a seat belt, or in the foot-well or car boot, possibly using a cylinder box. Liquid oxygen should always be transported in an upright position. A warning triangle may be displayed and insurance companies should be informed. (√)

Safety and home oxygen therapy

• Smoking cessation should be discussed and written education given to all patients prior to ordering home oxygen and at each subsequent review if the patient continues to smoke. (Grade C)

• Patients should be made aware in writing of the dangers of using home oxygen within the vicinity of any naked flame such as pilot lights, cookers, gas fires and candles. (Grade D)

• Patients and family members who continue to smoke in the presence of home oxygen should be warned of the associated dangers of smoking in the presence of oxygen. (Grade D)

Good practice points

• Safety should be a factor when making decisions regarding the ordering of oxygen. Education and written information should be provided to the patient and family or carers regarding the safe use of oxygen and its equipment. (√)

• The risks of prescribing oxygen to active smokers should be considered on a case-by-case basis: this should include a home visit to assess the patient's home situation, attitude toward risks and smoking behaviour. Home oxygen assessment services may decide not to prescribe home oxygen to smokers if the risks are in their judgement too high. Particular consideration needs to be given to risks to children and risks to neighbours in multiple occupancy dwellings. A risk assessment tool should be used, and the health professional who is undertaking the risk assessment may need to visit the home in conjunction with the local fire service and/or the oxygen contractor. Where there is reasonable doubt, the therapy should not be prescribed. (√)

• Patients who continue to smoke or live with other household smokers should be informed that the home oxygen order will be reviewed and evidence of increased risk may lead to withdrawal of home oxygen therapy. (√)

• Carbon monoxide monitoring and measuring urine cotinine may help identify those patients who continue to smoke. (√)

• Patients should be made aware that they should not use e-cigarettes and chargers within the vicinity of their home oxygen. (√)

• Oil-based emollients and petroleum jelly can support combustion in the presence of oxygen. Patients should be made aware that only water-based products should be used on the hands and face or inside the nose while using oxygen. (√)

• The oxygen supplier should be informed if the patient continues to smoke in order for the engineer to consider it in the home oxygen supplier risk assessment. (√)

• Patients and family or carers should be instructed not to remove the fire breaks or to change flow rate on their oxygen equipment. Only oxygen tubing and connections supplied by the oxygen company should be used. (√)

• The local fire service should be made aware of patients who are using oxygen at home and especially those who continue to smoke in order for a home safety assessment to be carried out. (√)

• Patients and carers should be aware that tubing should be checked on a regular basis and repositioned as necessary to ensure safety by preventing trips and falls. (√)

Evidence for use of LTOT in patients with COPD

Evidence for use of LTOT in patients with other respiratory or cardiac disease

Outcomes of LTOT in patients who continue to smoke

Accurate reports of individual smoking status can be difficult to obtain reliably in clinical practice. All trial data around smoking come from trials conducted with COPD patients.25 Unfortunately, the small numbers of patients included in the main RCTs is not optimal in discriminating between the impact of LTOT on smokers and non-smokers.4 ,5 There are no randomised or cohort studies investigating LTOT according to smoking status.

Cigarette smoking predisposes to secondary polycythaemia, accelerated decline in lung function and increased mortality in COPD. Thus, the beneficial effect of LTOT may be offset by raised carboxyhaemoglobin levels from continued cigarette smoking.26 The MRC study did not exclude smokers but did ‘urge all patients to give up smoking’.5 In the LTOT group, 52% of the patients were smokers (reduced to 44% at the end of the study). There were no recorded adverse events attributable to smoking in the MRC trial. There was an overall survival benefit in patients given oxygen (benefits in smoking and non-smoking populations were not reported separately).

The significant risk associated with combining cigarette smoking and oxygen therapy is reviewed in a later safety section of the guideline.

Evidence statement

• Evidence is insufficient to determine adverse clinical outcomes related to the effect of continuing smoking in LTOT patients compared to non-smokers. Evidence level 2+

Recommendation

• If LTOT is ordered for patients who are continuing to smoke, the potential for more limited clinical benefit should be discussed with the patient. (Grade D)

Referral and assessment of patients for LTOT

Referral to home oxygen assessment services provides the appropriate means for patients to be assessed for home oxygen therapy. Patients should have a definite diagnosis and be medically optimised prior to referral for assessment by an oxygen service. These services should have the appropriate clinical expertise, equipment and access to appropriate support services to enable the patient to have the best available care and outcomes, with the best use of resources. Guidance for commissioners in England and Wales has been published.27

Patient education at time of assessment

A few studies have evaluated the provision of patient education, usually in the form of verbal or written information, at the time of oxygen assessment. A comparison of patients who had received formal assessment with ABGs on two separate occasions together with education by a specialist respiratory team with patients commencing LTOT in primary care, mostly on the basis of oximetry alone, demonstrated a significantly higher compliance (82% vs 44%; p=0.002) and understanding of the rationale for treatment (93% vs 41%; p<0.00001).52 These findings were supported by a large case series of 930 patients in whom education consisting of a home visit by a nurse or physiotherapist was an important factor in those patients’ compliance with ≥15 h/day of oxygen use.53 Ordering LTOT on hospital discharge does not prepare patients for a follow-up assessment or the implications of oxygen removal if they no longer meet the criteria for LTOT:54 psychological dependence on oxygen therapy was reported as a major issue in these patients, causing distress for patients and staff as well as requiring significant resources and expertise to address.

Evidence statements

• Patients initiated on LTOT without formal education exhibit poor compliance with therapy. Evidence level 2+

• Providing written information to patients commenced on home oxygen in hospital does not prepare them for follow-up or the implication of not meeting the criteria for LTOT. Evidence level 3

Recommendations

• Patients initiated on LTOT should be provided with formal education by a specialist home oxygen assessment team to ensure compliance with therapy. (Grade D)

• Patients being commenced on home oxygen on discharge from hospital should be advised that home oxygen may be removed if reassessment shows clinical improvement. (Grade D)

Follow-up of LTOT patients

Follow-up of LTOT patients is necessary for a variety of reasons: to ensure that LTOT treatment is still required, that the oxygen order is still adequate (and therefore that the potential for healthcare gains such as survival are realised), that patients are compliant with treatment, and that any concerns or problems are addressed. Although home oxygen patients may be a relatively small group of lung disease patients in general, they are a very resource intensive group. Targeted follow-up of this group could provide significant benefits in terms of cost effective healthcare utilisation.

The original MRC and NOTT LTOT studies both provided titration of flow rate at a 3-month follow-up appointment as part of their protocol.4 ,5 Cottrell et al55 randomised 50 LTOT patients to follow-up at 2, 6 or 12 months. They costed hospital interventions given/required over a 1-year period, and found that the 2-monthly follow-up group had significantly higher evaluation costs with no benefit in terms of emergency department or hospital visits, length of stay in hospital or mortality: the only clinical benefit shown was an improvement in the psychological component of the sickness impact profile.

Other studies have focused on the setting for reassessment using different models, some of which might now be called ‘integrated respiratory services’. Cross-sectional studies have reported ‘added value’ from reviewing patients in their homes, which included identifying and correcting problems with the concentrator, humidifier, the length of the patient's tubing and factors impacting on the patient’s usage.56 ,57 In a prospective 10-year case–control study in which 217 LTOT patients were randomised to ‘home care’ (defined as 6-monthly hospital appointments and 2–3-monthly home visits) or standard care (management by hospital physician only), home care decreased exacerbation rates.58 Randomisation of 122 LTOT patients to follow-up with a hospital-based homecare programme (monthly phone call, home visits every 3 months, and home or hospital visits on a demand basis) or conventional medical care, demonstrated significantly decreased costs in the homecare follow-up group, which was mainly due to a reduction in use of hospital resources, despite the cost of running the service itself.59 Reports from focus groups60 and case series53 highlight the importance of education from specialist nurses or physiotherapists in increasing compliance and addressing patient concerns.

Withdrawal of home oxygen

Case series in which LTOT patients have been followed up have shown that a significant proportion of patients no longer required oxygen as originally ordered.33 ,61 In addition, it has been well recognised that compliance with LTOT can be poor and that withdrawal of home oxygen through non-use is sometimes indicated. Withdrawal of LTOT can be distressing to patients, challenging for staff and entail a significant use of resources.37 See appendix 7 for a suggested protocol for withdrawal of home oxygen therapy.

Evidence statements

• Follow-up of LTOT patients 3 months after starting LTOT, can ensure that LTOT is still required and that the flow rate is appropriate. Evidence level 1+

• Six-monthly follow-up has a similar effect to 2-monthly follow-up in terms of healthcare utilisation but at decreased cost. Evidence level 3

• Home follow-up alone or in combination with hospital follow-up is more effective than hospital follow-up. Evidence level 2+

• Follow-up with a specialist home oxygen assessment team including education improves compliance with LTOT. Evidence level 3

Recommendations

• LTOT patients should receive follow-up at 3 months after LTOT is ordered, which should include assessment of blood gases and flow rate to ensure LTOT is still indicated and therapeutic. (Grade A)

• LTOT patients should receive follow-up visits at 6–12 months after their initial 3-month follow-up, which can be either home based or in combination with hospital or clinic visits. (Grade D)

• Follow-up visits should be conducted by a specialist home oxygen assessment team with the necessary skills to deliver patient education and manage withdrawal of home oxygen. (Grade D)

Good practice point

• All patients for whom LTOT has been ordered should be visited at home within 4 weeks by a specialist nurse or healthcare professional with experience of domiciliary oxygen therapy. The visit provides an opportunity to highlight potential risks and should be used to reinforce education and offer support to the patient and carer. Compliance may be checked, along with smoking status, symptoms of hypercapnia and oxygen saturations on oxygen to check that oxygen is therapeutic. (√)

NOT in COPD patients with nocturnal desaturation

The worsening of hypoxaemia during sleep in patients with advanced COPD has been well established in many studies. There is retrospective evidence that nocturnal desaturation is associated with worse survival. The evidence as to whether patients who fail to meet the criteria for LTOT but are hypoxaemic during sleep benefit from NOT is assessed here.

There are only a small numbers of studies addressing this population of patients. Of these, three studies examined outcomes over 2–3 years, and three studies looked at mortality. Patients were recruited from out-patients settings, largely in teaching hospitals. In a multicentre study, 76 patients with COPD (obstructive sleep apnoea (OSA) excluded) were identified as having nocturnal desaturation but did not qualify for LTOT.62 A total of 41 patients were randomised to receive NOT which was titrated to achieve saturations >90% throughout the night. In the follow-up period, 22 patients went on to develop hypoxaemia requiring LTOT, 16 patients died (nine in the LTOT group), and there was no difference in the PAP (measured by cardiac catheter) between the two groups. A double-blind crossover study63 randomised 23 patients with COPD and nocturnal hypoxaemia to receive air or NOT over a 1-night period. No difference was seen in the quality of sleep (assessed by questionnaire and EEG) between the two groups. In six centres, 203 patients diagnosed with COPD and significant hypoxaemia (PaO₂ <7.8 kPa, 59 mm Hg) were randomised to continuous oxygen therapy (24 h) or NOT (12 h).4 The primary end point was all cause mortality. There was a 1.94 times increase in ‘all cause’ mortality in the NOT group compared to the continuous oxygen therapy group. A multicentre retrospective study investigated the data of patients from five centres who had polysomnography performed.64 Patients had mild to moderate daytime hypoxaemia with a PaO₂ >60 mmg Hg (8 kPa) and evidence of desaturation during sleep without signs of sleep apnoea. A total of 169 subjects with COPD (77 desaturators and 92 non-desaturators) were analysed. The mean survival was significantly less in the desaturator group (2.89±1.7 years vs 3.7±1.7 years; p<0.003). Thirty-five of the desaturator group were reported to have received some form of oxygen supplementation, however it was not clear how many hours this was for or if it was used nocturnally; on analysis it did not alter survival. In a double-blind study of 51 patients with moderate COPD and daytime PaO₂ >60 mm Hg including 38 with desaturation, patients were allocated to receive NOT at 3 L/min or room air.65 After 3 years, the NOT-treated group PAP had reduced by 0.49 kPa (3.7 mm Hg) and had increased in the air-treated group by 0.52 kPa (3.9 mm Hg; p<0.02). There was no difference in mortality; however, only nine in the sham group and seven in the oxygen group completed the study.

Evidence statements

• Patients with mild daytime hypoxaemia and nocturnal hypoxaemia have a worse survival compared to patients with no nocturnal desaturation. Evidence level 1+

• When administered to patients who are either normoxaemic or have baseline ABG levels above the threshold for LTOT, NOT alone does not show consistent improvements in pulmonary haemodynamics leading to a survival advantage. Evidence level 1+

• No additional significant benefit in sleep quality is derived from nocturnal supplemental oxygen in patients with nocturnal hypoxaemia. Evidence level 1−

Recommendation

• NOT is not recommended in patients with COPD who have nocturnal hypoxaemia but who fail to meet the criteria for LTOT. (Grade A)

Good practice point

• Other causes of nocturnal desaturation in COPD should be considered such as obesity hypoventilation, respiratory muscle weakness or OSA. (√)

NOT in patients with cardiac disease and nocturnal desaturation

A variety of factors can contribute to the development of nocturnal hypoxaemia in patients with heart failure: hypoventilation during sleep, reduced oxygen stores due to restricted lung volumes, sleep disordered breathing (SDB) and impaired gas exchange due to ventilation–perfusion mismatch. As previously, this section refers to patients who are either normoxic during the day, or have mild daytime hypoxaemia but do not fulfil LTOT criteria.

SDB in heart failure is due to central sleep apnoea (CSA) associated with Cheyne-Stokes respiration (CSR), often in combination with OSA. These frequently co-exist, and can be clinically difficult to differentiate. The presence of SDB is associated with atrial fibrillation and a worse New York Heart Association (NYHA) functional class. It is commoner in male patients, those over 60 years of age, and those with daytime hypocapnia (PaCO₂ <5.06 kPa, 38 mm Hg). SDB in heart failure can have few symptoms and come to light following reports by carers, or presents with symptoms of disrupted sleep such as increased daytime sleepiness, poor subjective sleep quality, insomnia, inattention and poor concentration. Recurrent nocturnal desaturations can lead to paroxysmal nocturnal dyspnoea, morning headaches, nocturnal angina and arrhythmias. SDB is important in the context of heart failure as it can predict mortality and also contribute to disease progression (through intermittent hypoxaemia and arousals inducing adrenergic surges and negative intra-pleural pressure swings which increase left ventricular transmural pressure leading to an increase in afterload). Some international guidelines on heart failure management advocate screening for SDB in selected patients. Treatment approaches have been to maximise treatment for the underlying cardiac disorder, and to consider additional therapies which include NOT or ventilatory support such as continuous positive airways pressure (CPAP), adaptive servo-ventilation (ASV) or NIV.

There are significant limitations in the evidence of the impact of treatment of SDB on heart-related outcomes: most studies evaluate surrogate outcomes (blood pressure, cardiac function, catecholamines) rather than clinically important outcomes (health-related quality of life, hospitalisation and mortality). In addition, the literature evaluating NOT against modalities of ventilation is limited.

NOT in patients with other respiratory diseases and nocturnal desaturation

AOT in patients not eligible for LTOT

There are a number of hypothetical benefits from the use of AOT in patients who are not hypoxaemic at rest but who desaturate on exercise, including increased oxygen transport, allowing greater utilisation of oxygen by exercising muscles, delayed onset of inspiratory muscle fatigue, reduction in symptoms of dyspnoea and improved right ventricular function.

Studies that have examined the use of AOT in non-LTOT users can be divided into those which have assessed the acute impact of AOT on exercise capacity during a single assessment, those studying the potential benefits of AOT during an exercise training programme, and those that have examined the potential longer term benefits of AOT on activity levels and quality of life.

Use of AOT during exercise

A Cochrane review of single assessment cross-over studies on the short-term impact of AOT versus placebo air on exercise capacity in moderate to severe COPD patients, reported that AOT significantly improved all outcomes of endurance exercise capacity (distance, time, number of steps) and that maximal exercise work rate also increased.82 Benefits in terms of reduced breathlessness, levels of oxygenation and minute ventilation at the time that the placebo test ended were also reported. However, the clinical significance of the size of improvement seen in these single assessment studies is unclear.83

The addition of supplemental oxygen during exercise training may allow patients who normally desaturate on exercise to tolerate higher levels of activity and therefore gain more from training. A meta- analysis included three RCTs examining the use of AOT during exercise training in COPD patients using comparable outcome measures.84 Although there were significant improvements in two parameters (constant power exercise time and constant power exercise end-of-test Borg score), there was no beneficial effect from oxygen-supplemented training in a number of other parameters including maximal exercise outcomes, functional exercise outcomes (6MWT), shuttle walk distance, health-related quality of life and oxygenation status. A recent single-blinded RCT examined use of AOT in a pulmonary rehabilitation programme in 51 ‘oxygen responders’ who were selected based on whether they had >10% improvement in exercise capacity when using AOT at baseline.85 Significant improvements in walking distance as measured by an endurance shuttle walking test pre- and post-course (490 m, 95% CI 228 to 750; p≤0.001) were shown for those who had used AOT during pulmonary rehabilitation. This area has also been reviewed in the BTS Guideline on Pulmonary Rehabilitation in Adults 2013.86

In a study of CF patients with advanced lung disease and normal resting oxygen saturations, patients could exercise for longer periods using supplemental oxygen during graded exercise tests.87 In a Cochrane review of AOT in CF, six studies evaluated oxygen supplementation during exercise. Oxygenation improved, but mild hypercapnia resulted and participants receiving oxygen therapy were able to exercise for a significantly longer duration.24 Evidence for an effect of AOT on daily activity is lacking, but in clinical practice use of AOT to support exercise, physiotherapy and activities of daily living in patients with CF is commonplace.

Long-term impact of AOT

There are limited data on whether the symptomatic benefits outweigh the practical difficulties associated with using AOT in everyday life.

A large parallel double-blinded 12-week RCT randomised 143 COPD patients to use of AOT versus a control group using compressed air.88 There were no significant improvements in the AOT group in terms of dyspnoea, quality of life or functional capacity, although only 50 patients were shown to desaturate (defined in this case as SpO₂ <88%). Average cylinder usage in both groups was low at just 40 min/day, and 46% of the AOT group reported they would prefer to cease using oxygen therapy altogether at the end of the study. A number of smaller studies (ie, n=20–45 patients) have examined the short-term benefits of AOT in either crossover or parallel blinded studies, lasting between 6 and 10 weeks.89–93 Modest statistically significant improvements were seen in exercise capacity93 and in health-related quality of life.89 However, the majority failed to show any sustained benefit from AOT in a number of variables, including dyspnoea, exercise capacity, St. George's Respiratory Questionnaire (SGRQ), health-related quality of life, activity levels, distance walked or time away from home.

AOT in patients eligible for LTOT

AOT is often ordered for LTOT patients, or those who require oxygen 24 h per day, to allow those who regularly mobilise outdoors to leave the house and maintain their oxygen saturations within desired levels. Conversely for patients who require LTOT or are dependent on oxygen 24 h per day, but are not able to mobilise outdoors, AOT may assist them to leave the house on an occasional basis, for example for hospital appointments.

Re-analysis of data from the NOTT study4 ,94 showed that in LTOT patients, AOT increased the chances of patients achieving the 15 oxygen hours per day threshold, which has been shown to confer survival benefits, a finding supported by other studies.95 However, AOT may prove burdensome for LTOT patients and not improve quality of life or exercise capacity. A 1-year double-blinded crossover trial in 24 LTOT patients allocated them to one of: standard therapy of LTOT via an oxygen concentrator only, standard therapy plus AOT, or standard therapy plus ambulatory compressed air. Use of AOT did not improve any of the primary outcome measures, including quality of life, exercise tolerance or daily duration of oxygen use, and the trial was stopped prematurely after an interim analysis.96 However, patients were expected to collect their oxygen cylinders from the hospital themselves, which is likely to have had an impact on usage.

Some patients find the weight of standard cylinders prohibits use, and so lightweight cylinders may be considered. Use of lightweight cylinders for AOT in comparison with ‘normal’ weight cylinders had no impact on the hours of use or on activity levels, both of which were low at randomisation and throughout the study in a 6-month unblinded RCT of 17 LTOT patients.97 Poor compliance with AOT may result from lack of information provision, perceived unreliability of the delivery system, system weight, self-consciousness in public, and carer issues surrounding managing and using AOT equipment.98

Assessment for AOT

Oxygen saturation (SpO₂) measured from a finger probe or the earlobe, is frequently used in clinical practice during exercise to assess patients and their response to AOT. When oximetry in 20 COPD patients performing 6MWTs with AOT both non-invasively using ear-oximetry (SpO₂) and invasively using CO-oximetry (SaO₂) was compared,97 flow rates were incrementally increased until both SaO₂ and SpO₂ were >90%. Significant differences were noted between SpO₂ and SaO₂ readings, which would potentially have led to different flow rates being ordered in 50% of subjects. For patients with a high respiratory rate, for example those with CF or ILD, assessment using Venturi oxygen at a flow rate sufficient to exceed the patient’s peak tidal (and exertional) inspiratory flow can offer advantages over oxygen therapy delivered by nasal cannulae. If total gas flow exceeds the patient's inspiratory flow rate, a Venturi mask will deliver an accurate oxygen concentration which may decrease the work of breathing and facilitate CO₂ control.99 See the section on equipment for information on oxygen conservers.

Evidence statements

• AOT has been shown to improve survival in patients on LTOT by helping them to achieve 15 h per day usage. Evidence level 1++

• AOT acutely increases exercise capacity in laboratory-based exercise tests in patients who are not eligible for LTOT but who desaturate during exercise. Evidence level 1+

• Long-term use of AOT has not been shown to confer any sustained benefits in dyspnoea, exercise capacity, functional capacity, time away from home or quality of life in patients who are not eligible for LTOT. Evidence level 1+

• AOT has not been shown to improve quality of life, exercise tolerance or oxygen usage in patients on LTOT. Evidence level 1−

• AOT leads to improvement in walking distance when given in a pulmonary rehabilitation programme setting to patients who have demonstrated a >10% improvement in exercise capacity when using AOT at baseline assessment. Evidence level 1−

Recommendations

• AOT should not be routinely offered to patients who are not eligible for LTOT. (Grade B)

• AOT should not be routinely offered to patients already on LTOT. (Grade D)

• AOT assessment should only be offered to patients already on LTOT if they are mobile outdoors. (Grade A)

• AOT should be offered to patients for use during exercise in a pulmonary rehabilitation programme or during an exercise programme following a formal assessment demonstrating improvement in exercise endurance. (Grade B)

Good practice points

• Patients started on AOT should be reviewed regularly. If AOT was started during an exacerbation or when unwell, an initial review at 4–6 weeks to check it is still indicated is essential. (√)

• Home visits may be useful to identify problems with equipment or set-up. Further reviews should be carried out every 6 months when stable, or sooner if the patient’s clinical status changes. (√)

• AOT therapy may offer patients with active lifestyles or active treatment regimens (eg, CF) additional benefits. All patients should be assessed for AOT in the context of their daily activity and therapies. (√)

• It is recognised that there may be some patients, for example with ILD and disabling breathlessness, who do not qualify for LTOT but who do desaturate on exercise, who may benefit from AOT. Once all other medical interventions have been optimised, these patients could be considered for AOT following formal assessment and AOT use could continue following demonstration of benefit and compliance. (√)

• Patients with high respiratory rates (common in CF and ILD) should receive AOT at a flow rate via a Venturi mask, which exceeds their peak tidal and exertional inspiratory flow, and be supplied with home oxygen equipment which is able to deliver the required high flow rates. (√)

• AOT may be offered to LTOT patients who could otherwise not achieve 15 h per day oxygen usage, or who are severely hypoxaemic and are too symptomatic to leave their house without supplemental oxygen but may need to do so, for example to attend GP or hospital appointments. Formal assessment is not required in these circumstances. (√)

• For suggested patient selection criteria and an AOT assessment procedure for AOT during pulmonary rehabilitation, see appendix 1.

Effects of POT in comparison with air

The studies reviewed excluded patients with cognitive impairment106 ,107 and those with a prognosis of <1 month.107 Oxygen was delivered by nasal cannula or mask, and flow rate varied from 2 to 5 L/min. Studies also varied regarding duration of oxygen therapy, ranging from 15 min106 and 60 min108 to 15 h.107 Oxygen was delivered at rest in two studies,106 ,109 on exertion in one108 and continuously for 15 h in another study.107 No studies looked at life expectancy, but one study reported quality of life.107

A double-blind crossover study randomised 51 patients with advanced cancer, 17 of whom were hypoxaemic (SpO₂ <90%) to 15 min of either air or palliative oxygen.106 Patients (whether hypoxaemic at baseline or not) improved symptomatically with both air and oxygen, but there were no significant differences between the treatments. A systematic review and meta-analysis of the efficacy of palliative oxygen for relief of dyspnoea in hypoxaemic (mean SpO₂ 88%) or non-hypoxaemic cancer patients included 134 patients.108 Although palliative oxygen was administered in a variety of ways (nasal cannula or mask; rest or 6MWT; flow rate 3–5 L/min), there was no improvement in dyspnoea. A double-blind RCT compared air with palliative oxygen (2 L/min for 15 h per day for 7 days from a concentrator) in 239 patients with cancer or end-stage cardiorespiratory disease.107 There was no statistically significant difference between the two groups in breathlessness (measured twice daily), frequency of side effects, or change in quality of life between groups. Finally, a cohort study failed to demonstrate any symptomatic benefit over 2 weeks of the provision of home palliative oxygen as measured by routine recording of breathlessness with each clinical encounter with a specialist community palliative care team.110

Effects of POT in comparison with other therapies such as opiates, fan therapy and cognitive behaviour therapy

There are no reported studies comparing POT with fan therapy, cognitive behavioural therapy or other techniques for symptomatic relief of breathlessness.

One study assessed the effects of oxygen and opioid treatment on ventilation and palliation of dyspnoea in hypoxaemic (SpO₂ <90%) and non-hypoxaemic (SpO₂ ≥90%) palliative care patients (either opioid-naive or pre-treated with strong opioids) in a prospective non-randomised study.109 Whereas opioid administration resulted in a significant decrease in the intensity of dyspnoea in hypoxaemic or in non-hypoxaemic patients, nasal oxygen therapy did not. There was no significant correlation between intensity of dyspnoea and SpO₂, and no significant difference between hypoxaemic or non-hypoxaemic patients with regard to transcutaneous CO₂ increase or SpO₂ decrease after administration of opioids.

Evidence statements

• Measurements of oxygenation do not correlate well with the subjective experience of dyspnoea in patients with cancer or end-stage cardiorespiratory disease. Evidence level 2+

• Hypoxaemic patients do not experience a significant difference in symptoms between air and POT despite having improved oxygen saturations when administered oxygen. Evidence level 2+

• Non-hypoxaemic patients or those with mild levels of hypoxaemia who would not normally qualify for LTOT do not experience symptomatic benefit with POT compared with air. Evidence level 1++

• Opioids are significantly better than POT in reducing the intensity of dyspnoea in non-hypoxaemic or hypoxaemic patients. Evidence level 1+

Recommendations

• Patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness should not receive treatment with POT if they are non-hypoxaemic or have mild levels of hypoxaemia above current LTOT thresholds (SpO₂ ≥92%). (Grade A)

• Patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness should receive assessment for a trial of treatment with opiates from an appropriately trained healthcare professional. (Grade A)

• Patients with cancer or end-stage cardiorespiratory disease who are experiencing intractable breathlessness should receive assessment for a trial of treatment with non-pharmacological treatments including fan therapy, from an appropriately trained healthcare professional. (Grade D)

Good practice point

• POT may on occasion be considered by specialist teams for patients with intractable breathlessness unresponsive to all other modalities of treatment. In those instances, individual formal assessment of the effect of palliative oxygen on reducing breathlessness and improving quality of life should be made. (√)

• For suggested patient selection criteria and a protocol for POT assessment, see appendix 3.

Use of SBOT in respiratory disease

The studies reviewed were limited to patients with COPD and included normoxic and hypoxaemic patients with moderate to severe disease. Two studies examined oxygen delivery before and after exercise, while four studies administered oxygen after exercise. One study that examined the benefit of oxygen after exercise included patients given LTOT,111 however hypoxaemic and non-hypoxaemic patients were not analysed separately. There were no studies that specifically examined the benefits of SBOT ordered for hypoxaemic patients alone.

In order to examine the effect of supplemental oxygen before and after exercise in stable COPD patients with moderate to severe disease who demonstrated exercise desaturation, Nandi et al112 undertook two double-blind randomised studies. In the first study, 34 subjects received either cylinder air or oxygen 28% at a flow rate of 4 L/min for 10 min before a 6MWT. In the second study, 18 subjects received either cylinder air or cylinder oxygen for 5 min immediately after a 6MWT. Those that took part in both studies did so on different days. Distance walked, oxygen saturations and breathlessness as measured by a VAS were recorded as was time to recovery. No difference was found in distance walked, subjective breathlessness or recovery time when oxygen was administered prior to exercise. Nor was there any significant difference in distance walked, recovery time or breathlessness when oxygen was administered following exercise. The authors concluded that no recommendation could be made to support a useful therapeutic role for SBOT.

Similarly, SBOT was not found to have any effect on performance when administered before and after exercise in 22 non-hypoxaemic COPD patients with moderate to severe disease.113 Subjects undertook four 6MWTs at each of two sessions. Cylinder air or oxygen was randomly administered prior to the first two walk tests and during recovery following the final two tests. The group found no significant difference in distance walked or breathlessness as measured by the Borg score for air and oxygen given prior to exercise and no significant difference in mean time to resting Borg score when oxygen was given after exercise.

Another study compared oxygen, air, fan and no treatment in 34 stable patients with moderate to severe COPD who were short of breath on minimal exertion and who were not hypoxaemic (SaO₂ ≤93% at rest).114 Patients undertook an exercise step test on four occasions and after each test were given either oxygen 4 L/min from a face mask, air from a face mask, air from a fan, or no intervention. Fourteen patients desaturated on exercise below 90%. Oxygen therapy had no significant effect on Borg scores even for those patients who desaturated. Oxygen saturation rose more quickly and to a higher level when the oxygen mask was used compared with other treatments (p<0.009), but this increase of 2% had no effect on subjective breathlessness as measured by the Borg score.

Patients were asked to choose whether they received treatment before or after exercise in a study that examined 22 stable COPD patients with moderate to severe disease.111 Subjects were studied at home undertaking an activity of choice (mean resting SaO₂ 93.1% (range 82–98%)). All had domiciliary oxygen ordered for them and 50% were on LTOT. In this double-blind study, cylinder air or oxygen was randomly administered after exercise. Interestingly, all subjects chose after exercise. The exercise was repeated after a rest period and the alternative treatment administered. There was no difference in recovery times with oxygen compared with air. Five patients were able to correctly identify oxygen from air on both occasions. This group had shorter subjective and objective recovery times when compared with the rest of the group, although this did not reach statistical significance.

A reduced recovery time as measured by a VAS was associated with oxygen use compared with compressed air or placebo in a study of 19 subjects with stable severe COPD (mean (SD) PaO₂ 8.05 (1.52) kPa).115 Subjects undertook three step tests to maximal dyspnoea and then were administered either cylinder oxygen 67% via a mask, cylinder air at the same flow for 20 min, or no mask in random order. The results were not found to be reproducible when the seven responders were re-tested after a time lapse of between 1 week and 1 month.

In a study undertaken by Stevenson and Calverley, 18 stable COPD patients were included, none of whom were hypoxaemic at rest, although six patients did desaturated on exercise (range 88–96%).116 Patients attended on two occasions at least 1 week apart. At each visit, patients performed a maximal cardiorespiratory exercise test following which they randomly received either air or oxygen (FiO₂ 0.4) in a single-blind crossover fashion. At one visit the subject remained instrumented during recovery, while at the other visit the mouthpiece and nose clips were replaced with a Venturi mask at a flow rate of 10 L/min. The results revealed that following exercise, administration of oxygen when compared with compressed air was associated with a reduced ventilatory effort and dynamic hyperinflation resolution was shorter; however, there was no reduction of breathlessness as measured by the Borg score at any time during recovery between oxygen and air inhalation, nor did oxygen influence the rate at which symptoms were resolved. The authors concluded that the routine use of oxygen to aid recovery of symptoms after exercise does not appear to be justified.

Healthcare utilisation and quality of life were measured in a randomised double-blind placebo-controlled trial in patients with moderate to severe disease following an admission to hospital with an exacerbation of COPD.117 A total of 78 non-hypoxaemic patients were recruited and were randomised to cylinder air, cylinder oxygen or usual care for 6 months following discharge from hospital. The subjects who were randomised to cylinder air or cylinder oxygen were instructed to use it at 2 L/min via nasal cannulae as needed for relief of distressing or limiting breathlessness. Cylinder use was self-recorded in patient diaries. Healthcare utilisation was assessed by number of COPD-related readmissions and unscheduled emergency department or primary care visits. Quality of life was measured using the Chronic Respiratory Disease Questionnaire (CRQ), the Hospital Anxiety and Depression Scale (HAD) and the Medical Outcomes Study Short Form (SF-36). There was no significant difference between patient groups in any of the health-related quality of life measures apart from the emotions domain of the CRQ for the usual care group. Hospital readmission and healthcare utilisation were high. However, there was no significant difference between groups. Cylinder use was initially high but fell rapidly within weeks in both the cylinder air and oxygen groups. The authors conclude that these results do not offer any support for the use of SBOT on discharge from hospital following an acute exacerbation of COPD.

Evidence statements

• SBOT does not improve exercise tolerance or reduce breathlessness when administered either before or following exercise to hypoxaemic or non-hypoxaemic patients with moderate to severe COPD. Evidence level 1++

• SBOT does not improve health-related quality of life or reduce healthcare utilisation when ordered for patients following an acute exacerbation of COPD. Evidence level 1++

Recommendations

• SBOT should not be ordered for use prior to or following exercise in hypoxaemic or normoxic patients with COPD. (Grade A)

• SBOT should not be ordered on discharge from hospital for non-hypoxaemic patients with severe COPD. (Grade A)

Use of SBOT in CH

CH pain is the most severe of the primary headache syndromes. It is characterised by periodic attacks of strictly unilateral pain associated with ipsilateral cranial autonomic symptoms. The majority of patients have episodic cluster headache (ECH), with cluster periods that typically occur in a circannual rhythm, while 10% have the chronic form (CCH), with no significant remissions between cluster periods. High flow oxygen therapy is used to relieve pain and is delivered usually from static oxygen cylinders in the patient's home.

In a double-blind randomised, placebo-controlled cross-over trial, 109 adults were treated for CH attacks with either 100% oxygen (12 L/min) or inhaled air, given via a facial mask for 15 min at the start of an attack. Fifty-seven patients with ECH and 19 with CCH were available for the analysis.118 Oxygen was significantly superior to placebo in elimination of pain or provision of ‘adequate pain relief’ at 15 min in 78% of patients (vs 20% with air). In a case series of 52 randomly selected out-patients with either active ECH or CCH, 100% oxygen was administered through a facial mask at a rate of 7 L/min for 15 min at the onset of each of 10 cluster attacks.119 Overall, 75% of patients obtained significant relief (defined as complete or almost complete reduction of pain in seven of 10 attacks within 15 min) from cluster pain. These findings were supported by a double-blind crossover study of 19 patients where use of SBOT (6 L/min via non-rebreather face masks for 15 min) produced significantly higher average relief scores for all oxygen-treated patients.120 A case report of three patients unresponsive to oxygen given at 7–10 L/min reported complete or near complete alleviation of headache after 100% oxygen at a rate of 14–15 L/min.121 Non-responders to SBOT have more often smoked in the past (p=0.014), had longer CH attacks (p=0.049), and reported more inter-ictal headache (p=0.02) than responders.122

A single-blind crossover trial of 50 patients has compared sublingual ergotamine tartrate to SBOT (100% oxygen via a face mask, at a rate of 7 L/min for 15 min) for symptomatic relief of cluster attacks showed no statistical difference between treatment groups.119

NICE (National Institute of Health and Care Excellence) guidelines on the diagnosis and management of headaches in young people and adults, published in September 2012, recommend oxygen and/or a subcutaneous or nasal triptan for the acute treatment of CH.123 It is recommended that oxygen should be given at a flow rate of at least 12 L/min with a non-rebreather mask and a reservoir bag arranged as home oxygen. (NICE refers to ambulatory oxygen in this context which differs from the definition of ambulatory oxygen used in this guideline).

Evidence statement

• SBOT delivering high flow oxygen (12 L/min via a non-rebreather mask) is an effective symptomatic treatment for acute CH attacks. Evidence level 1+

Recommendation

• SBOT delivering high flow oxygen therapy (12 L/min via a non-rebreather mask) should be offered to treat acute attacks of CH. (Grade A)

Good practice point

• Appropriate equipment will need to be provided in order to ensure delivery of high flow rate oxygen at 12 L/min for CH using a non-rebreather mask. Patients will usually have warning of a CH attack, and so provision should be made for urgent 4 h installation of home oxygen, if available, rather than a permanent home supply being provided. (√)

Oxygen source: concentrators, cylinders and liquid oxygen – description and indications for use

Home oxygen can be delivered from cylinders, concentrators or as liquid oxygen. Each of these oxygen sources can be static or portable, and the source selected is dependent upon the mobility and clinical circumstances of the patient, along with the costs of installation and supply as determined by the oxygen provider. There are few published studies comparing the different modes of oxygen source in different clinical situations. Some studies have compared similar devices, but many of these are now out-dated and technology has superseded them.

Oxygen delivery: nasal cannulae and masks, oxygen-conserving devices and trans-tracheal devices–description and indications for use

Methods of home oxygen delivery depend upon the patient's requirements and the setting for delivery of care. Interfaces used for home oxygen fall into two main categories: nasal cannulae and face masks using the Venturi system. Trans-tracheal delivery is rarely used but will be briefly described. In addition, oxygen-conserving devices may be used to facilitate oxygen delivery. Most home oxygen tubing has a ‘fire break’ inserted at the patient end of the tubing just before the nasal cannula or mask: this is a thermal fuse which when triggered will stop the oxygen supply in the event of fire.

Other equipment: trolleys and backpacks, humidifiers–description and indications for use

Patient compliance with treatment is greatly improved with supplementary equipment which may help address practical issues around home oxygen provision.

Smoking and home oxygen therapy

There is increasing recognition of the significant risks of fire and personal injury associated with smoking and the use of home oxygen therapy. LTOT patients can be enabled to achieve smoking cessation,52 but despite these necessary interventions, many patients with respiratory disease, and especially COPD, continue to smoke. In addition, the clinician’s assessment of smoking status relies mainly on patients’ testimony and evidence has shown that this can be inaccurate.61 There have been no high quality trials to enable an objective assessment of the risks and benefits of the use of home oxygen in those who continue to smoke. However, there is emerging evidence from case reports of the risks of continued smoking and oxygen use. A study in four American states from 2000 to 2007 documented 38 fatalities associated with smoking and oxygen therapy, and 16 non-fatal injuries reported which included harm to two fire-fighters and one policeman.151 Of the fatalities, 34 (89%) were using LTOT and smoking at the time the fire began, three were household members of smokers receiving LTOT, and one was a non-smoker with LTOT who was unintentionally ignited by a family member who was smoking. Two retrospective case series of patients admitted to burns units reported harm caused by smoking while using home oxygen.152 ,153 Of 27 patients over a 7-year period who were identified with burns directly attributed to home oxygen use, 24 were smoking while using oxygen, two were lighting pilot lights, and one was lighting his wife's cigarette.152 Of 21 patients in a 12-year period who experienced partial thickness burn injuries, 57% sustained inhalation injury, five (22%) required intubation and mechanical ventilation, and two died during hospitalisation.153 In addition, 86 home oxygen-related burn injuries were documented in a retrospective study designed to compare the outcome characteristics of patients admitted to a burns unit who had been intubated compared with those who had not been intubated.154 Lighting a cigarette was the cause of the majority of injuries (87%), while exposure to other naked flame sources accounted for others (lighting a cooker 5%, electrical spark 5%, candles 2%, and other open flames 1%). There are an increasing number of anecdotal reports of e-cigarettes and chargers causing fire-related incidents if used in the vicinity of home oxygen.

No studies were identified that examined improvements in safety if smoking status in home oxygen patients was monitored either by urinary cotinine measurements or CO (carbon monoxide) monitoring compared to no monitoring.

Role of risk assessments

Recognition of the danger of fire and personal injury caused by smoking and home oxygen use has led to pragmatic approaches to individual assessment of risks on a case-by-case basis. A risk assessment may be conducted by the home oxygen assessment service and the fire and rescue service according to local protocols. Home oxygen suppliers carry out a formal risk assessment twice under the current UK National Framework Agreement: once at the time of taking the order and a field-based assessment at the patient's location when the order is delivered. Further risk assessment should then take place every 6 months thereafter. See appendix 4 for examples of risk assessment tools.

Some home oxygen services have adopted the practice of asking patients to sign a disclaimer acknowledging the risks of behaviours such as smoking near home oxygen.

Responsibilities of the oxygen supplier

Certain responsibilities around risk assessment are outlined in the National Framework Agreement for home oxygen services (December 2000, transitioned to NHS England 2013), which outlines the contractual obligations of home oxygen supply companies in England and Wales. In Scotland, a national home oxygen service was established by Health Facilities Scotland in 2012, and the single contracted supplier is also obliged to carry out a similar risk assessment prior to oxygen installation.

These risk assessment obligations for home oxygen suppliers in England are:

• A desk risk assessment should be conducted upon receipt of a home oxygen order to ensure that the oxygen equipment ordered matches the requirements and the equipment can be delivered safely.

• The supplier shall ensure that a field-based risk assessment is carried out at the time of installation to verify whether the requirement of the home oxygen order form (HOOF) can be supplied safely and in accordance with the requirements. See appendix 5 for details of HOOF forms.

• A field-based risk assessment must be conducted in each patient's primary and/or secondary location every 6 months after the initial field-based risk assessment to ensure that risk is monitored on an ongoing basis. The supplier shall file a copy of such field-based risk assessment and provide it to the clinical commissioning group home oxygen service lead where risk has been identified

• The field-based risk assessment will identify potential fire-related risk in the patient's home. During this assessment, the supplier shall check for the presence of an operational smoke detector or alarm. In the event that a smoke detector or fire alarm is not present, the supplier shall inform the local fire authorities of this fact, together with any specific fire risks that have been identified.

• The concentrator and any cylinders are positioned with sufficient ventilation and at a safe distance from any naked flame, cooking or heating appliance.

• Oxygen equipment should be placed in a position where it will not cause an obstruction to patients or family members, especially those who may have mobility or sight impairment.

• A fixed installation should be considered to fix tubing and reduce trip hazard.

• A second concentrator may be necessary in larger properties or if patients have difficulty using the stairs.

• Verbal and written information should be given to the patient or carer regarding the use of the equipment provided.

• The engineer should be satisfied that the patient can use the provided oxygen equipment safely.

• The oxygen concentrator must be checked regularly to ensure the filters are cleaned, the flow metres are accurate, and the concentrator delivers oxygen at the correct concentration.

• The oxygen contractor should inform the assessment service of any safety issues concerning the patient and the oxygen equipment and its use.

• The data collected by the oxygen contractor related to safety such as fire and accidents as a result of oxygen equipment and its use in the home, should be made available to oxygen assessment services.

Role of the fire and rescue service

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.

Trips and falls

Patients with home oxygen often have mobility or sight impairment, and equipment and tubing can jeopardise safety. No studies were found that examined the number of accidents that occurred as the result of home oxygen equipment or tubing.

Evidence statements

• Serious burns, inhalation injury or death can be caused by using oxygen while smoking or using oxygen near a naked flame. Evidence level 3

• Patients who are educated regarding the dangers of smoking and using oxygen are more likely to quit smoking. Evidence level 2+

Recommendations

• Smoking cessation should be discussed and written education given to all patients prior to ordering home oxygen and at each subsequent review if the patient continues to smoke. (Grade C)

• Patients should be made aware in writing of the dangers of using home oxygen within the vicinity of any naked flame such as pilot lights, cookers, gas fires and candles. (Grade D)

• Patients and family members who continue to smoke in the presence of home oxygen should be warned of the associated dangers of smoking in the presence of oxygen. (Grade D)

Good practice points

• Safety should be a factor when making decisions regarding ordering home oxygen. Education and written information should be provided to the patient and their family or carers regarding the safe use of oxygen and its equipment. (√)

• The risks of prescribing oxygen to active smokers should be considered on a case-by-case basis: this should include a home visit to assess the patient's home situation, attitude toward risks and smoking behaviour. Home oxygen assessment services may decide not to prescribe home oxygen to smokers if the risks are in their judgement too high. Particular consideration needs to be given to risks to children and risks to neighbours in multiple occupancy dwellings. A risk assessment tool should be used, and the health professional who is undertaking the risk assessment may need to visit the home in conjunction with the local fire service and/or the oxygen contractor. Where there is reasonable doubt, the therapy should not be prescribed. (√)

• Patients who continue to smoke or live with other household smokers should be informed that the order for home oxygen will be reviewed and evidence of increased risk may lead to withdrawal of home oxygen therapy. (√)

• Carbon monoxide monitoring and measuring urine cotinine may help identify those patients who continue to smoke. (√)

• Patients should be made aware that they should not use e-cigarettes and chargers within the vicinity of their home oxygen. (√)

• Oil-based emollients and petroleum jelly can support combustion in the presence of oxygen. Patients should be made aware that only water-based products should be used on the hands and face or inside the nose while using oxygen. (√)

• The oxygen supplier should be informed if the patient continues to smoke in order for the engineer to consider it in the home oxygen supplier risk assessment. (√)

• Patients and family or carers should be instructed not to remove the fire breaks or to change the flow rate on their oxygen equipment. Only oxygen tubing and connections supplied by the oxygen company should be used. (√)

• The local fire service should be made aware of patients who are using oxygen at home and especially those who continue to smoke in order for a home safety assessment to be carried out. (√)

• Patients and carers should be aware that tubing should be checked on a regular basis and repositioned as necessary to ensure safety by preventing trips and falls. (√)