Long-term oxygen therapy and home non-invasive ventilation

Definition and principle of LTOT. Long-term oxygen therapy is supplemental oxygen given for at least 15 hours per day, which was shown in the NOTT and MRC trials to improve survival in severe COPD with persistent hypoxaemia. Along with smoking cessation, it is one of only two interventions proven to prolong life in COPD. It must be prescribed during a period of clinical stability and to current non-smokers.

Criteria for LTOT. Assess by arterial blood gas on two occasions at least 3 weeks apart when stable:

Benefits and limitations. LTOT improves survival (about 50% of patients survive a further 3 years), polycythaemia and neuropsychiatric function; cognitive gains are small and mostly in the oldest groups; quality-of-life benefit is modest and inconsistent. There are no randomised data on LTOT in advanced old age, or in isolated nocturnal or exertional hypoxaemia. Low BMI and comorbidity predict earlier death; disability, low BMI, lung function and LTOT use are the main mortality predictors in older COPD patients.

Practical and geriatric issues. Fire risk if the patient or household continues to smoke. The concentrator and long tubing are a trip and falls hazard — engineers should fit room-switching mechanisms. Cognitive impairment and poor manual dexterity threaten safe use. Care home logistics matter: staff training, and portable cylinders or conservers if the day room is far from the bedroom. Target saturation 88–92% in CO retainers — excessive oxygen 2 depresses hypoxic drive, increases coronary and cerebral arterial resistance and worsens acidosis.

Acute non-invasive ventilation. Indicated in acute hypercapnic respiratory failure with pH < 7.35 despite maximal medical therapy. Compared with standard treatment, NIV reduces mortality, the need for intubation and length of hospital stay. Bilevel positive airway pressure (BiPAP) is used. NIV is an appropriate ceiling of treatment in frail older patients with a do-not-intubate decision. High-flow nasal oxygen is safe and effective in exacerbated COPD with normocapnic or hypercapnic failure and is useful for do-not-intubate patients or intermediate care outside the ICU.

Home (domiciliary) NIV. Indicated for chronic hypercapnic respiratory failure — most importantly persistent hypercapnia (PaCO > 7 kPa) reassessed 2–4 weeks after an exacerbation, and also in obesity hypoventilation 2 syndrome, neuromuscular disease and chest-wall deformity (kyphoscoliosis). CPAP — not NIV — is the treatment for obstructive sleep apnoea. Success requires adequate cognition, mask tolerance, carer support and structured follow-up; palliative NIV may relieve symptoms at the end of life.

GOLD 2025 / 2026 reports confirm that LTOT is NOT indicated for isolated moderate resting desaturation or exercise-induced desaturation alone (based on the LOTT trial, which found no benefit in survival or hospitalisation) — oxygen should only be prescribed for severe resting hypoxaemia. Conversely, long-term home NIV should be considered in patients with severe chronic hypercapnia and a history of hospitalisation for acute respiratory failure, following the HOT-HMV trial, which showed that home NIV added to oxygen prolonged the time to readmission or death.