Synopsis
Distinguish chronic hypoxaemia from hypoventilation, prescribe home oxygen only after formal assessment, and coordinate safe long-term ventilatory support with specialist follow-up.
- Oxygen treats hypoxaemia; ventilation treats inadequate carbon dioxide clearance. A patient can need one, both or neither, and pulse oximetry alone cannot distinguish them.
- Refer stable COPD patients for LTOT assessment when resting saturation is persistently 92% or less, but prescribe from specialist blood-gas assessment rather than oximetry alone.
- NICE supports LTOT in stable COPD with PaO2 below 7.3 kPa, or 7.3 to 8 kPa with qualifying complications such as pulmonary hypertension, oedema or secondary polycythaemia.
- Confirm chronic stability with repeated arterial blood gases at least three weeks apart and titrate oxygen while checking for worsening hypercapnia or acidosis.
- Survival benefit depends on substantial daily use; NICE advises at least fifteen hours each day for eligible COPD patients.
- Do not use short-burst oxygen for chronic breathlessness in people who are not hypoxaemic; fans, rehabilitation and cause-directed symptom care are usually more appropriate.
- Ambulatory oxygen requires formal exercise assessment and a device the person can actually carry and use; desaturation alone does not guarantee functional benefit.
- Smoking, vaping, flames, gas cooking and some emollients create serious fire risk around oxygen; assess the whole household and document mitigation.
- Home NIV is specialist treatment for chronic ventilatory failure from neuromuscular, chest-wall, obesity-related or selected COPD disease, with interface, settings and backup planning individualised.
- Review oxygen and ventilation after discharge, after clinical change and at least through the national service intervals; withdraw equipment when reassessment shows it is no longer indicated.
Key red flags
Morning headache, hypersomnolence, orthopnoea, disturbed sleep, weak cough, recurrent chest infections or raised bicarbonate and PaCO2 suggests hypoventilation needing specialist sleep and ventilatory assessment.
Drowsiness, rising PaCO2 or acidosis during oxygen titration in COPD, obesity, neuromuscular or chest-wall disease means oxygen must be paired with urgent ventilatory assessment rather than simply withheld or increased.
Persistent hypercapnia, recurrent admission, worsening symptoms, major mask leak, pressure injury or inability to tolerate the device requires early home-ventilation review and sometimes a different interface or mode.
Active smoking or vaping near oxygen, open flames, unsafe storage, cognition problems, poor electrical resilience or repeated falls can make the prescription hazardous and requires multidisciplinary risk mitigation.
Investigation priorities
Screen for referral to formal home-oxygen assessment.
Management branches
Resting hypoxaemia persists after recovery and optimal treatment of the underlying disease.
- Ensure clinical stability, optimise lung and cardiac disease, address tobacco dependence and obtain repeated resting oximetry before specialist referral.
- The home oxygen service obtains serial stable blood gases, checks NICE eligibility and titrates the flow while monitoring PaCO2 and pH.
- Agree equipment, prescribed flow and daily duration, complete household safety assessment, and educate the patient and carers about fire and trip risk.
- Review face to face with blood gas within three months of initiation and at least annually, withdrawing LTOT if eligibility no longer persists.