Guidelines for Long-Term Oxygen Therapy (LTOT)
LTOT should be prescribed for patients with chronic hypoxemia (PaO₂ ≤7.3 kPa or ≤55 mmHg) for a minimum of 15 hours per day, as this improves survival and pulmonary hemodynamics. 1
Patient Selection Criteria
Primary Indications
- COPD patients:
Other Conditions Requiring LTOT
- Interstitial lung disease (ILD): Same criteria as COPD 1
- Cystic fibrosis: Same criteria as COPD 1
- Pulmonary hypertension: When PaO₂ ≤8 kPa (60 mmHg) 1
- Advanced cardiac failure: Same criteria as COPD 1
- Neuromuscular/chest wall disorders: Consider NIV first, with LTOT as additional therapy if hypoxemia persists 1
Assessment Process
Initial Referral
- Refer patients with stable resting SpO₂ ≤92% for blood gas assessment 1
- Consider referral at SpO₂ ≤94% if peripheral edema, polycythemia, or pulmonary hypertension is present 1
Timing of Assessment
- Assess after a period of clinical stability (at least 8 weeks from last exacerbation) 1
- Avoid prescribing LTOT during acute exacerbations 1
Blood Gas Measurement
- Initial assessment requires arterial blood gas (ABG) sampling 1
- Two ABG measurements at least 3 weeks apart are required to confirm need for LTOT 1
- For oxygen titration, capillary blood gases (CBG) can be used to measure PaCO₂ and pH 1
- Cutaneous capnography can be used to measure PaCO₂ but not pH 1
Oxygen Prescription Details
Flow Rate
- Start at 1 L/min and titrate up in 1 L/min increments until SpO₂ >90% 1
- Confirm with ABG that PaO₂ ≥8 kPa (60 mmHg) is achieved 1
- For non-hypercapnic patients, increase flow rate by 1 L/min during sleep 1
- Assess need for increased flow during exercise for active patients 1
Duration
Special Considerations
Hypercapnia Management
- Monitor patients with baseline hypercapnia for respiratory acidosis after each flow rate titration 1
- If PaCO₂ rises >1 kPa (7.5 mmHg) during assessment:
Smoking
- Discuss limited clinical benefit with patients who continue to smoke 1
- Provide smoking cessation support 3
Follow-up Protocol
Initial Follow-up
- Home visit within 4 weeks by a specialist nurse or healthcare professional 1, 3
- Check compliance, smoking status, symptoms of hypercapnia, and oxygen saturation 1
Ongoing Monitoring
- 3-month follow-up with blood gas assessment to confirm continued need 1, 3
- Subsequent follow-ups every 6-12 months 1, 3
- Annual review to reassess prescription and adjust flow rate as necessary 3
Patient Education and Safety
- Provide formal education by a specialist home oxygen assessment team 1
- Warn about dangers of using oxygen near open flames 3
- Advise on securing oxygen equipment during transport 3
- Inform patients that home oxygen may be removed if reassessment shows clinical improvement 1
Common Pitfalls to Avoid
- Premature prescription: Avoid prescribing LTOT during or immediately after an exacerbation 1
- Inadequate monitoring: Failure to reassess after 3 months may result in unnecessary continuation 1
- Overlooking hypercapnia: Always monitor for worsening CO₂ retention during oxygen titration 1
- Insufficient duration: Less than 15 hours daily use significantly reduces survival benefit 2
- One-size-fits-all approach: Patients with cognitive or physical impairments may need a single fixed flow rate 1
- Routine overnight flow increase: Evidence challenges the recommendation to routinely increase overnight oxygen flow 4
LTOT remains a cornerstone treatment for chronic hypoxemia that improves survival when properly prescribed and monitored, though its benefits are primarily established in COPD patients with robust evidence from early trials showing reduced mortality (33% vs. 55%) 2.