What is the most appropriate treatment for a 55-year-old woman with chronic obstructive pulmonary disease (COPD) on a combination of long-acting β2-agonist (beta-2 agonist) and inhaled glucocorticoid and albuterol (salbutamol) as needed, presenting with worsening symptoms, hypoxemia (oxygen saturation 86%), abnormal arterial blood gas (ABG) results, bilateral lower extremity edema, and high mean pulmonary artery pressure?

Start Oxygen Therapy Immediately

This patient requires supplemental oxygen therapy as the most appropriate immediate treatment given her hypoxemia (oxygen saturation 86%, PaO2 8.6 kPa) during a COPD exacerbation. 1, 2

Clinical Reasoning

Why Oxygen Therapy is the Priority

The patient presents with significant hypoxemia that requires immediate correction:

• Current oxygen saturation is 86%, well below the target of ≥90% 1, 3
• PaO2 is 8.6 kPa (approximately 64 mmHg), which is below the therapeutic goal of >8.0 kPa (60 mmHg) 1, 2
• Prevention of tissue hypoxia supersedes CO2 retention concerns, even though this patient has respiratory alkalosis (pH 7.6, PCO2 7.5 kPa) 4, 1

The European Respiratory Society explicitly recommends supplemental oxygen for hospitalized COPD patients when oxygen saturation falls below 90%, with the goal of maintaining saturation ≥90% and PaO2 ≥8.0 kPa 1. This patient clearly meets these criteria.

Implementation Strategy

Start with low-dose oxygen delivery: 3

• Begin with 24% oxygen via Venturi mask or 1-2 L/min via nasal cannulae 3
• Target oxygen saturation of 88-92% to avoid worsening respiratory acidosis 3
• Monitor arterial blood gases within 60 minutes of initiating oxygen therapy 3

Titrate oxygen flow carefully: 1, 3

• Gradually increase oxygen concentration until PaO2 is above 8.0 kPa (60 mmHg) 1
• Monitor for CO2 retention; if acidemia develops, consider noninvasive ventilation 4, 2

Why Not the Other Options?

Oral diuretics (Option B): While the patient has bilateral lower extremity edema and elevated pulmonary artery pressure (52 mmHg) suggesting cor pulmonale, diuretics should only be administered if there is peripheral edema AND raised jugular venous pressure 3. This patient explicitly has no jugular venous distension, making diuretics inappropriate at this time. Additionally, cor pulmonale management should be addressed only after oxygenation is optimized, as the condition is secondary to chronic hypoxemia 2.

Oral prednisone (Option C): The patient is already on combination inhaled corticosteroid therapy. While systemic corticosteroids (30-40 mg prednisone daily for 10-14 days) are recommended for COPD exacerbations 4, 3, correcting hypoxemia takes immediate priority. Corticosteroids would be an appropriate next step after oxygen therapy is initiated.

Mucolytics (Option A): There is no evidence-based indication for mucolytics as first-line treatment in this clinical scenario. The patient's primary problem is hypoxemia, not mucus clearance 4.

Additional Considerations

Long-Term Oxygen Therapy Assessment

This patient may qualify for long-term oxygen therapy (LTOT) given: 4, 2

• High pulmonary artery pressure (52 mmHg) indicating pulmonary hypertension
• Peripheral edema
• Hypoxemia

The American Thoracic Society indicates LTOT is appropriate for stable patients with PaO2 ≤7.3 kPa (55 mmHg) or PaO2 between 7.3-8.0 kPa with evidence of pulmonary hypertension or peripheral edema 2. However, if oxygen is prescribed during an exacerbation, arterial blood gases should be rechecked in 30-90 days during a stable period to determine ongoing need 4.

Common Pitfalls to Avoid

• Do not withhold oxygen due to concerns about CO2 retention - tissue hypoxia prevention is the priority 4, 1
• Avoid uncontrolled high-flow oxygen which may worsen hypercapnia 3
• Do not fail to reassess arterial blood gases after initiating oxygen therapy 3
• Monitor for respiratory acidosis development requiring noninvasive ventilation 4, 3