Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Distinguish chronic hypoxaemia from hypoventilation, prescribe home oxygen only after formal assessment, and coordinate safe long-term ventilatory support with specialist follow-up.
LTOT is a disease-modifying treatment for selected people with severe chronic resting hypoxaemia, best established in COPD. It is not a generic treatment for breathlessness and should not be ordered from one low saturation during an exacerbation. The home oxygen team confirms clinical stability, repeated arterial oxygen tension, tolerability of the prescribed flow, carbon dioxide response, intended hours and equipment. A temporary discharge order after acute illness must be actively reassessed because oxygenation may recover.
Home ventilation addresses pump failure. During sleep, weakened respiratory muscles, obesity-related loading or severe chest-wall restriction may first produce nocturnal hypoventilation, morning headache, unrefreshing sleep and daytime fatigue before daytime hypercapnia develops. Bilevel NIV supplies inspiratory pressure support and a backup strategy tailored by a home mechanical ventilation service. CPAP splints an obstructed upper airway but does not provide the same ventilatory assistance.
Safety and usability decide real benefit. Oxygen tubing causes trips; concentrators need electricity and backup; cylinders require secure storage; masks cause pressure injury, leak, dryness and claustrophobia. Patients and carers need equipment training, cleaning, travel and power-cut plans, emergency contacts and clear instructions on which settings they may alter. Neither oxygen nor ventilation should be changed casually by an untrained clinician without knowing the original prescription.
Persistently low resting saturation when clinically stable, especially with oedema, pulmonary hypertension or raised haematocrit, should trigger formal LTOT assessment rather than an immediate unsupervised home order.
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.
Oxygen accelerates combustion and can worsen hypercapnia. Never smoke or vape near equipment; avoid flames and unsafe petroleum-based products, maintain target saturation, and do not alter flow without the assessment plan.
Device weight and pulse-dose delivery can negate benefit. It is not routine for isolated breathlessness, and air travel requires separate assessment; retain the same household fire and storage precautions.
Do not interchange masks, circuits or oxygen ports casually because delivered ventilation can change. Monitor leak, skin injury, aspiration and secretion ability; acute drowsiness or device failure requires urgent assessment.
Pulse oximetry identifies who may need assessment but cannot measure arterial oxygen tension accurately enough to prescribe LTOT or reveal carbon dioxide retention.
Severe dyspnoea can occur with normal oxygenation, and silent chronic hypoxaemia can be minimally breathless. Oxygen should follow physiology, not symptom intensity alone.
CPAP supplies one distending pressure to splint the upper airway; bilevel NIV adds inspiratory support and often a backup rate to augment ventilation.
Oxygen started around an exacerbation may no longer be required once inflammation, ventilation-perfusion mismatch and mobility recover, making planned reassessment essential.
A theoretically correct prescription fails if the patient cannot lift a cylinder, fit a mask, tolerate noise or respond to a power cut.
Ordering LTOT from one low saturation during an acute exacerbation without stable blood-gas confirmation.
Prescribing oxygen for breathlessness in a normoxic patient and overlooking rehabilitation, fan therapy or the underlying cause.
Increasing oxygen for drowsy hypercapnic failure without checking blood gas and providing ventilatory support.
Confusing CPAP for upper-airway obstruction with bilevel ventilation for hypoventilation.
Ignoring smoking, vaping, emollient, flame, trip and electricity risks in the patient's actual home.
Failing to review and withdraw temporary discharge oxygen when chronic eligibility is not confirmed.
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A patient with COPD is clinically stable and repeatedly has resting SpO2 of 91% in clinic. What is the best next step?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes