Long-Term Oxygen Therapy (LTOT)

Long-Term Oxygen Therapy (LTOT): Clinical Use, Benefits & Guidelines

Long-Term Oxygen Therapy (LTOT) helps reverse hypoxaemia and prevent hypoxia in individuals with chronic lung diseases. Clinical studies have demonstrated that LTOT significantly improves life expectancy, particularly in patients with conditions like COPD.

Clinical Evidence and Benefits

A landmark study by the British Medical Research Council (MRC) found that patients receiving oxygen for 15 hours per day, including during sleep, had lower mortality compared to those not receiving oxygen. Similarly, the Nocturnal Oxygen Therapy Trial (NOTT) showed that continuous oxygen use (around 19 hours per day) resulted in even better survival outcomes compared to shorter durations.

Though the exact mechanism behind these benefits is not fully understood, improvements in pulmonary haemodynamic are considered a contributing factor. Long-term use has also shown a modest reduction in pulmonary artery pressure and helps reverse secondary polycythemia, improve cardiac function, reduce dyspnoea, and enhance quality of life and exercise tolerance.

Oxygen Use During Sleep

Many patients with chronic oxygen needs experience significant desaturation at night even with daytime flow rates. Adjusting flow rates or providing supplemental oxygen during sleep can help correct nocturnal hypoxaemia. While there’s evidence of improved quality of life with nocturnal oxygen, its effect on long-term survival remains inconclusive unless there’s significant daytime hypoxaemia.

Oxygen Use During Exercise

Supplemental oxygen during physical activity can reduce shortness of breath and improve endurance. Patients may experience improved breathing patterns, reduced ventilation needs, and less dynamic hyperinflation. LTOT is often prescribed for patients who are hypoxaemic at rest or who desaturate only during exertion, although long-term outcome data specific to exercise-induced hypoxaemia is still limited.

Determining Oxygen Flow Settings

Oxygen settings should be customized based on the patient’s needs during:

• Rest: Flow should maintain SpO₂ ≥ 90%. Use ABG to confirm accuracy.

• Sleep: May require an increased flow rate or monitored through overnight oximetry or polysomnography.

• Exercise: Flow should maintain PaO₂ > 60 mmHg or SaO₂ > 90% during physical activity.

Appropriate Candidates for LTOT

Patients with chronic, stable respiratory disease should be assessed under optimal medical management. Candidates typically include:

Optimizing Medical Treatment

Before initiating LTOT, it’s essential to ensure the patient is on a full and effective treatment plan. In the NOTT study, nearly 50% of initially qualifying patients no longer needed oxygen after four weeks of optimized therapy. Reassessment after stabilization is crucial.

Initiating and Managing LTOT

• An arterial blood gas (ABG) test after 30 minutes on room air is standard before starting LTOT.

• Pulse oximetry is useful for ongoing flow adjustments but not for initial qualification.

• LTOT should ideally be provided continuously (24 hours/day), including portable options for active patients.

Portable and Stationary Oxygen Systems

• Ambulatory Systems: Lightweight, lasting ≥ 4–6 hours at 2 L/min, and easy to carry.

• Stationary Systems: Delivered via concentrators, compressed gas, or liquid forms.

• Larger Cylinders: Suitable for limited mobility beyond the concentrator range.

Continued Assessment

Some patients initially require oxygen during acute exacerbations but may no longer need it after recovery. These individuals should be reevaluated 30–90 days post-stabilization. Conversely, stable patients who qualify for LTOT typically require long-term treatment.

LTOT as a Long-Term Commitment

Evidence shows oxygen may have reparative effects. Discontinuation in stable patients can lead to decline, suggesting that once LTOT is established, it should be viewed as a permanent component of care unless a physician determines otherwise.

Reimbursement and Documentation

To ensure insurance coverage, documentation must support medical necessity with detailed clinical and physiological data. Most healthcare systems follow similar criteria.

Patient Education and Adherence

Patient understanding and compliance play a critical role in successful LTOT outcomes. Addressing misconceptions, emotional reactions, and social concerns is essential. Encouraging education and providing reassurance about the therapy’s life-enhancing potential can significantly improve adherence.