01Purpose and principlesWhat the treatment does and how it fits into care.
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.
Key points
- 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.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
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.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Stable resting pulse oximetryFirst step - Why
- Screen for referral to formal home-oxygen assessment.
- Interpretation and limitations
- Persistent saturation of 92% or less in stable COPD supports referral, not automatic prescription. Oximetry is affected by perfusion and cannot measure PaCO2 or establish LTOT eligibility.
- 02
Serial arterial blood gases while clinically stable - Why
- Confirm chronic hypoxaemia and assess carbon dioxide safety.
- Interpretation and limitations
- NICE uses two measurements at least three weeks apart in stable COPD. Interpret PaO2 with PaCO2, pH and bicarbonate; repeat during oxygen titration when hypercapnia risk exists.
- 03
Ambulatory oxygen walk assessment - Why
- Test exercise desaturation and practical benefit from a chosen device.
- Interpretation and limitations
- Use a repeatable walking protocol, comparing exercise performance and symptoms with the equipment the person will use. A corrected saturation without meaningful mobility benefit may not justify burden.
- 04
Overnight oximetry with transcutaneous carbon dioxide or sleep study - Why
- Identify sleep-disordered breathing and nocturnal hypoventilation.
- Interpretation and limitations
- Desaturation alone cannot separate OSA from hypoventilation. Carbon dioxide pattern, respiratory events and daytime gas determine whether CPAP, NIV or another pathway is appropriate.
- 05
Spirometry, vital capacity and respiratory muscle assessment - Why
- Define disease causing chronic pump or gas-exchange failure.
- Interpretation and limitations
- Serial decline and supine fall can support neuromuscular weakness; obstruction supports COPD. Results guide referral and monitoring but do not replace symptoms and blood gases.
- 06
Home oxygen and ventilation risk assessment - Why
- Identify fire, equipment, adherence, carer and access hazards.
- Interpretation and limitations
- Assess household smoking, flames, emollients, tubing, electricity, dexterity, cognition and emergency access. Mitigation is individual; unresolved material risk requires multidisciplinary review of whether and how treatment can be supplied.
04Treatment approachPreparation, options, escalation and aftercare.
01LTOTConfirm durable oxygen needFirst stepResting hypoxaemia persists after recovery and optimal treatment of the underlying disease.+
- 1Ensure clinical stability, optimise lung and cardiac disease, address tobacco dependence and obtain repeated resting oximetry before specialist referral.
- 2The home oxygen service obtains serial stable blood gases, checks NICE eligibility and titrates the flow while monitoring PaCO2 and pH.
- 3Agree equipment, prescribed flow and daily duration, complete household safety assessment, and educate the patient and carers about fire and trip risk.
- 4Review face to face with blood gas within three months of initiation and at least annually, withdrawing LTOT if eligibility no longer persists.
02Home NIVAssess chronic hypoventilationSymptoms, raised bicarbonate or PaCO2, weakness or chest-wall disease suggests ventilatory pump failure.+
- 1Confirm the underlying neuromuscular, obesity, chest-wall, sleep or obstructive disorder and identify bulbar, secretion and carer-support needs.
- 2Obtain daytime gas, respiratory function and overnight oxygen-carbon dioxide assessment through a home mechanical ventilation service.
- 3Select CPAP only for predominant obstructive upper-airway disease; use bilevel or other NIV when ventilatory assistance and backup breathing are needed.
- 4Titrate interface and settings to symptoms, gas exchange, sleep and adherence, then provide equipment failure, power-cut and acute-illness plans.
03DischargeReassess temporary oxygenHome oxygen is supplied during or immediately after an acute hospital admission.+
- 1Record that need may be temporary, the target saturation, flow, hypercapnia risk and named service responsible for reassessment.
- 2EscalationProvide fire, smoking, equipment and escalation education before discharge, confirming the patient can use the exact device safely.
- 3Arrange home oxygen team review within the recommended interval with stable blood gas; do not allow a temporary order to become indefinite by default.
- 4Withdraw or revise oxygen systematically if physiology recovers, explaining breathlessness strategies and coordinating supplier collection.
04Acute changeUse the emergency support planEscalationA home-supported patient develops infection, drowsiness, secretion failure or escalating breathlessness.+
- 1EscalationUse the written escalation contact and assess ABCDE, target saturation, ventilator function, mask or circuit, secretions and likely precipitant.
- 2Give oxygen to the documented target and obtain blood gas early when hypercapnic risk or altered consciousness is present.
- 3Do not make large unplanned setting changes; involve the home ventilation team and acute respiratory or critical-care service according to severity.
- 4After recovery, review whether equipment, settings, airway-clearance plan and treatment ceiling remain appropriate.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Long-term oxygen therapy
Use the specialist-titrated flow for at least fifteen hours daily in eligible stable COPD, with separate rest, sleep and exertion instructions where prescribed.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.
Specialist-prescribed ambulatory oxygen
Use only the assessed portable device and flow during the specified activity, for the duration demonstrated to provide practical benefit.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.
Nocturnal non-invasive ventilation
Use the individual home-ventilation interface, mode, inspiratory and expiratory pressures, backup rate and oxygen entrainment prescribed by the specialist service.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.
06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- For LTOT, reassess stable blood gas and risk within three months after initiation and at least annually through the home oxygen service.
- Review prescribed versus actual daily oxygen use, device function, smoking or vaping, household flames, tubing falls and travel or power resilience.
- For home NIV, monitor symptoms, daytime PaCO2 or bicarbonate, overnight oxygen-carbon dioxide control, device adherence, leak and residual respiratory events.
- Inspect mask pressure areas, nasal and oral dryness, eye leak, secretion clearance, bulbar safety and the patient's or carer's ability to assemble the circuit.
- After any hospital admission, weight change, neuromuscular decline or recurrent morning symptoms, seek early specialist reassessment rather than waiting for routine annual review.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Saturation is a screening tool
Pulse oximetry identifies who may need assessment but cannot measure arterial oxygen tension accurately enough to prescribe LTOT or reveal carbon dioxide retention.
Breathlessness is not hypoxaemia
Severe dyspnoea can occur with normal oxygenation, and silent chronic hypoxaemia can be minimally breathless. Oxygen should follow physiology, not symptom intensity alone.
CPAP and NIV differ
CPAP supplies one distending pressure to splint the upper airway; bilevel NIV adds inspiratory support and often a backup rate to augment ventilation.
Recovery changes eligibility
Oxygen started around an exacerbation may no longer be required once inflammation, ventilation-perfusion mismatch and mobility recover, making planned reassessment essential.
Equipment is part of treatment
A theoretically correct prescription fails if the patient cannot lift a cylinder, fit a mask, tolerate noise or respond to a power cut.
08Common pitfallsFrequent interpretation and management errors.
- 01
Ordering LTOT from one low saturation during an acute exacerbation without stable blood-gas confirmation.
- 02
Prescribing oxygen for breathlessness in a normoxic patient and overlooking rehabilitation, fan therapy or the underlying cause.
- 03
Increasing oxygen for drowsy hypercapnic failure without checking blood gas and providing ventilatory support.
- 04
Confusing CPAP for upper-airway obstruction with bilevel ventilation for hypoventilation.
- 05
Ignoring smoking, vaping, emollient, flame, trip and electricity risks in the patient's actual home.
- 06
Failing to review and withdraw temporary discharge oxygen when chronic eligibility is not confirmed.