What are the treatment options for oxygen (O2) support in Chronic Obstructive Pulmonary Disease (COPD)?

Oxygen Support in COPD

Supplemental oxygen should be provided to hospitalized COPD patients when oxygen saturation falls below 90%, with the primary goal of maintaining saturation ≥90% and PaO2 ≥8.0 kPa (60 mmHg), prioritizing prevention of tissue hypoxia over concerns about CO2 retention. 1

Acute/Hospital Setting

Indications and Goals

• Initiate supplemental oxygen when saturation drops below 90% during acute exacerbations or hospitalization 1
• Target oxygen saturation ≥90% and/or PaO2 ≥8.0 kPa (60 mmHg) 1
• Avoid elevating PaCO2 by >1.3 kPa (10 mmHg) or lowering pH below 7.25 1

Delivery Methods and Titration

• Start with low-dose oxygen: 24% via Venturi mask or 1-2 L/min via nasal cannulae 1
• Primary delivery devices include nasal cannula and Venturi masks 1
• Alternative devices: non-rebreather masks, reservoir cannulae, or transtracheal catheters 1
• Monitor arterial blood gases regularly and adjust oxygen flow until target saturation is achieved 1

Critical Principle

Prevention of tissue hypoxia supersedes CO2 retention concerns 1. If CO2 retention occurs, monitor for acidemia; if acidemia develops, consider noninvasive or invasive mechanical ventilation rather than withholding oxygen 1

Long-Term Oxygen Therapy (LTOT)

Survival Benefit

LTOT is one of only two interventions (along with smoking cessation) proven to improve survival in COPD patients with chronic respiratory failure 1, 2. This represents the strongest mortality benefit available for severe COPD 1.

Prescribing Criteria

LTOT should be prescribed when patients meet the following criteria during a stable 3-4 week period on optimal medical therapy 1:

• Primary indication: PaO2 ≤7.3 kPa (55 mmHg), with or without hypercapnia 1
• Secondary indications: PaO2 7.3-7.9 kPa (55-59 mmHg) with evidence of:
  • Pulmonary hypertension 1
  • Cor pulmonale 1
  • Polycythemia 1
  • Severe nocturnal hypoxemia 1

Critical Assessment Requirements

• Arterial blood gas measurements must be obtained on at least two occasions, three weeks apart, when clinically stable 1
• Patients must have FEV1 <1.5 liters 1
• Contraindication: Active smoking (LTOT should not be prescribed to continuing smokers due to lack of benefit and safety concerns) 1

Dosing and Duration

• Flow rate: 1.5-2.5 L/min via nasal cannulae, adjusted to achieve PaO2 >8.0 kPa (60 mmHg) 1
• Minimum duration: 15 hours daily, including during sleep (greater survival benefit shown with continuous use) 1
• Verify with arterial blood gases that the set flow achieves target PaO2 without unacceptable PaCO2 rise 1
• Reassess dosage at least annually 1

Delivery Systems

• Oxygen concentrators: Easiest mode requiring only electricity supply, preferred for LTOT 1
• Nasal cannulae: Most commonly used delivery device 1
• Venturi masks: Deliver more accurate oxygen concentration 1
• Transtracheal oxygen: Consider for patients with high oxygen demands or cosmetic preferences 1
• Liquid oxygen: Allows portable system for travel and exercise 1

Post-Hospitalization Management

• Patients started on oxygen during acute exacerbation should have arterial blood gases rechecked 30-90 days after discharge 1
• Do not discontinue oxygen in patients who previously qualified during stable periods, even if PaO2 improves, as withdrawal may negate reparative effects and cause clinical deterioration 1
• Discontinue oxygen only if patient no longer meets prescribing criteria after recovering from exacerbation, as there is no proven survival benefit for mild hypoxemia 1

Monitoring and Follow-Up

• Six-monthly follow-up and reassessment required 1
• Home visits by respiratory health workers optimize compliance and proper use 1
• Patient education improves adherence to therapy 1

Ambulatory Oxygen

• Improves exercise tolerance and breathlessness in selected patients 1
• Active patients on LTOT require portable oxygen systems 1
• Consider for documented oxygen saturation fall >4% below 90% on standard walking test, with demonstrated improvement in exercise tolerance or breathlessness 1

Common Pitfalls

• Failing to reassess arterial blood gases during stable periods: Many patients are inappropriately prescribed oxygen based solely on measurements during acute exacerbations 1
• Inadequate duration of use: LTOT must be used minimum 15 hours daily; shorter durations do not provide survival benefit 1
• Withholding oxygen due to CO2 retention fears: Tissue hypoxia prevention is the priority; manage acidemia with ventilatory support if needed 1
• Premature discontinuation: Withdrawing oxygen from patients who qualified during stable periods may be detrimental even if PaO2 improves 1