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Home > Professional Reference > Prescribing Oxygen

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Prescribing Oxygen

This PatientPlus article is written for healthcare professionals so the language may be more technical than the condition leaflets. You may find the abbreviations list helpful.

The NHS oxygen contract

The method of prescribing home oxygen was changed in February 2006. Details of the changes are available in the EMIS home oxygen order forms (HOOF) wizard1 but the main changes are:2

  1. All oxygen therapy is to be supplied by designated contractors - there are four contractors that cover England and one of these also covers Wales.
  2. Hospital specialists can directly prescribe oxygen on dedicated HOOF forms and this is the same for both primary and secondary care.
  3. Ambulatory oxygen therapy is now available on prescription - previously this was rarely funded by hospitals and had to be purchased privately or obtained through charities.

Note, the home oxygen contract is changing in 2011/12 and as such this data may not reflect what is currently available in your area. This article will be revised once details are available.

More details on the new oxygen contract

  • All patients needing home oxygen in England and Wales must now be referred to a hospital specialist (e.g. chest physician), for diagnosis and full physiological assessment including blood gases.
  • A HOOF is then faxed to the contractor who decides on the appropriate equipment. GPs will no longer use FP10 prescriptions for pharmacists to provide cylinders through a local supplier.3
  • Using a HOOF, GPs are only able to order short burst oxygen for palliative use or emergency use while awaiting assessment.
  • Home oxygen is now funded from PCT budgets, whether ordered by a GP or hospital. A home oxygen record (HOR) form should be sent to the GP with diagnosis, blood gas measurements (at least 2), flow rate, hours of use per day, use of nasal cannulae or masks and provision of humidifier.
  • The aim is to improve quality of life for patients on long-term oxygen and to reduce costs by matching provision to need.
  • A consent form must be completed by all patients. This includes those already using oxygen concentrators but in such cases a HOOF will not be needed.

The National Patient Satisfaction Survey of the Home Oxygen Service published by the Department of Health in 2008 reported that 88% of patients believe that their quality of life has improved since receiving the service.4

Types of oxygen therapy

There are now 5 types of oxygen provision:

  1. Long-term oxygen therapy (LTOT).
  2. Ambulatory - new development with light portable cylinders lasting 6 hours.
  3. Short burst - via a cylinder.
  4. Travel - usually portable cylinders. For holidays in the UK, the usual contractor will make reciprocal arrangements with another contractor to supply oxygen at the holiday destination.
  5. Emergency oxygen - can be supplied within 4 hours. Enough for 3 days will be arranged prior to specialist assessment. Out of hours arrangements exist - but the emergency doctor may need to carry a supply of HOOFs to leave with the patient or fax to suppliers. A second HOOF will be required if the patient is to continue oxygen after the emergency period pending assessment.

Indications for long-term oxygen therapy

The concentration of oxygen depends on the condition being treated:

  • High concentration oxygen, up to 60%, is safe in conditions such as pneumonia, pulmonary thrombo-embolism and fibrosing alveolitis.
  • Low concentration oxygen (of 24-28%) is used in patients with chronic obstructive pulmonary disease (COPD) or other conditions causing underventilation and CO2 retention. 24-28% oxygen significantly increases haemoglobin saturation, without risking further underventilation and a rising pCO2, which can cause coma and death. Repeated blood gas measurements are required to assess the correct oxygen concentration.

British Thoracic Society Guidelines5

Long-term oxygen therapy is indicated for the following conditions:

Chronic hypoxaemia

In patients with chronic hypoxaemia, LTOT should usually be prescribed after appropriate assessment, when the PaO2 is consistently at or below 7.3 kPa (55 mmHg) when breathing air during a period of clinical stability. Clinical stability is defined as the absence of exacerbation of chronic lung disease for the previous five weeks. The level of PaCO2 (which may be normal or elevated) does not influence the need for LTOT prescription.

In addition, LTOT can be prescribed in chronic hypoxaemia patients when the clinically stable PaO2 is between 7.3 kPa and 8 kPa, together with the presence of one of the following:

  • Secondary polycythaemia
  • Clinical and or echocardiographic evidence of pulmonary hypertension

LTOT should not be prescribed in patients with chronic hypoxaemia with a PaO2 value above 8kPa .

Nocturnal hypoventilation

  • Obesity
  • Neuromuscular/spinal/chest wall disease
  • Obstructive sleep apnoea with continuous positive airway pressure (CPAP) therapy

Assessment for LTOT requires referral to a physician with a specialist interest in these disorders. LTOT will normally be used as an adjunct to non-invasive ventilation (NIV) or CPAP.

Palliative Use
Domiciliary oxygen therapy can be prescribed for palliation of dyspnoea in pulmonary malignancy and other causes of disabling dyspnoea due to terminal disease. One study however suggested that opiates are better in controlling dyspnoea in this situation and implied that it may only be effective if hypoxia is demonstrated.6 This was supported by a large meta-analysis.7

Smoking and home oxygen

Patients should be made aware of the dangers of continuing to smoke in the presence of home oxygen therapy.

Assessment

Assessment is important because some breathless patients are not hypoxic, and hypoxic (even cyanosed) patients are not always breathless.8 Detailed assessment involving structured exercise testing and blood gas measurements may be needed.

Equipment

Oxygen cylinders

These cylinders have 'medium' (2 litres/minute) and 'high' (4 litres/minute) settings. Portable oxygen cylinders last approximately 2 hours at 2 litres/minute. Oxygen concentrators are more economical than cylinders for more than 8 hours a day. Exceptionally, 2 oxygen concentrators can be combined using a 'Y' connection. Accessories include face mask, nasal cannulae and humidifier. Masks supply either 24% or 28% oxygen. Nasal cannula allows the patient to talk and eat but the concentration is not controlled and mucosal drying can occur in sensitive individuals. Flow rate is normally 2 l/minute via nasal cannulae or from a 24% controlled oxygen face mask, aiming for a PaO2 of 8 kPa. If oxygenation is insufficient, the oxygen flow rate should be increased gradually. Some patients may require greater than 4 l/minute and may need an additional oxygen concentrator.

Long-term oxygen therapy

See BTS guidelines' box above for indications. LTOT prolongs survival in COPD if given for at least 15 hours daily to include night time (arterial hypoxaemia is worse at night), to raise oxygen tension above 8 kPa.

Oxygen should not be started at the time of hospital discharge, when patients are still recovering from an exacerbation. Patients should be seen 5 weeks later to assess blood gases when they are clinically stable, then visited within 4 weeks by a respiratory nurse specialist, be reviewed by a specialist after 3 months and have 12-monthly blood gases.

Ambulatory oxygen therapy

Most patients needing this will also be using LTOT. Housebound patients may benefit from occasional use (e.g. up to an hour a day). More active patients on LTOT may benefit from ambulatory oxygen for longer, though few need it for longer than 4 hours daily. The same flow rate should be used as for LTOT. Further assessment is not essential unless the flow rate needs re-adjusting. The aim is to enable the patient to leave the home to improve quality of life, although expectations should be reasonable. One study of COPD patients found that although the use of ambulatory oxygen enhanced activities, the actual amount of physical activity did not increase.9

The cost of ambulatory oxygen does not appear to be excessive compared to conventional oxygen cylinder use.10

Patients not on LTOT but with exercise desaturation (a fall in SaO2 of 4% below 90%) may benefit from ambulatory oxygen to increase exercise capacity. This group needs detailed assessment with walking tests. Ambulatory oxygen should only be prescribed if there is evidence of exercise desaturation and improvement in exercise capacity.

Short burst oxygen therapy11

Short burst therapy (e.g. for 10 to 20 minutes) is indicated to relieve dyspnoea in palliative care or episodic breathlessness, not relieved by other treatments in severe COPD, interstitial lung disease or heart failure. Review annually and repeat assessment in the event of clinical deterioration.

Patient education

Education should cover diagnosis, use of ambulatory oxygen therapy, principles of treatment, maintenance of portable equipment, servicing arrangements and electricity reimbursement, use of nasal cannulae or masks, requirement for humidifier, contact telephone number and advice on travel. Further education is provided by the engineer at the time of delivery. A family member or carer should attend the education sessions.

N.B: The patient should be made aware of the dangers of smoking and fire risk.

Pulse oximetry

Used to measure SaO2, can be a useful guide:

  • To spot exercise desaturation (a drop of at least 4% below 90%).
  • To diagnose sleep apnoea.
  • To monitor ambulatory oxygen flow rate (aim to maintain above 90% during exercise).

Oxygen for children12

  • Many children only need oxygen for a limited period.
  • Assessment is different to adults due to difficulty of arterial blood sampling and growth and neuro-development considerations.
  • Specific equipment is required to allow for lower oxygen flows.
  • Almost all children receiving long-term oxygen therapy also require ambulatory oxygen therapy. Many children require LTOT overnight only (less than the 15 hours that forms part of the adult LTOT definition).
  • Provision of oxygen may be necessary at school.
  • All children require supervision from a parent/carer.

Document references

  1. HOOF Wizard; Help for doctors wishing to order oxygen for patients. Provided by Dr Ian Rubenstein of Eagle House Surgery, Enfield; log in required to access information
  2. Wedzicha JA, Calverley PM; All change for home oxygen services in England and Wales. Thorax. 2006 Jan;61(1):7-9.
  3. Home Oxygen Service: Briefing Note, Dept of Health; Advice for contractors, including names of regional suppliers
  4. Department of Health; Patients endorse Home Oxygen Service 2008.
  5. Working Group on Home Oxygen Services, British Thoracic Society (January 2006); Clinical Component for the home oxygen service in England and Wales
  6. Clemens KE, Quednau I, Klaschik E; Use of oxygen and opioids in the palliation of dyspnoea in hypoxic and non-hypoxic palliative care patients: a prospective study. Support Care Cancer. 2009 Apr;17(4):367-77. Epub 2008 Aug 22. [abstract]
  7. Uronis HE, Currow DC, McCrory DC, et al; Oxygen for relief of dyspnoea in mildly- or non-hypoxaemic patients with cancer: a systematic review and meta-analysis. Br J Cancer. 2008 Jan 29;98(2):294-9. Epub 2008 Jan 8. [abstract]
  8. Bruera E, de Stoutz N, Velasco-Leiva A, et al; Effects of oxygen on dyspnoea in hypoxaemic terminal-cancer patients.; Lancet. 1993 Jul 3;342(8862):13-4. [abstract]
  9. Sandland CJ, Morgan MD, Singh SJ; Patterns of domestic activity and ambulatory oxygen usage in COPD. Chest. 2008 Oct;134(4):753-60. Epub 2008 Jul 14. [abstract]
  10. Mapel DW, Robinson SB, Lydick E; A comparison of health-care costs in patients with chronic obstructive pulmonary disease using lightweight portable oxygen systems versus traditional compressed-oxygen systems. Respir Care. 2008 Sep;53(9):1169-75. [abstract]
  11. Drug and Therapeutics Bulletin; Why prescribe short-burst oxygen? 2007 Sep;45(9):70-2.
  12. Clinical Component for the Domiciliary Oxygen Service for Children in England and Wales, British Thoracic Society, 2005.

Internet and further reading

  • HOOF Wizard; Help for doctors wishing to order oxygen for patients. Provided by Dr Ian Rubenstein of Eagle House Surgery, Enfield; log in required to access information
  • Home Oxygen Service; homeoxygen.nhs.uk 2009.; NHS website for public and professionals
The clinicians responsible for the production of this document are:
Original Author: Dr Gurvinder Rull
Last Checked: 15 Jun 2009		Current Version: Dr Laurence Knott
Document ID: 470  Version: 5		Peer Reviewer: Dr Huw Thomas
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