A 68-year-old male with severe chronic obstructive pulmonary disease (COPD) presents with worsened dyspnea, increased sputum volume, and sputum purulence (Anthonisen Type 1 exacerbation). Blood gas shows pH 7.32, PaCO2 56 mmHg, and PaO2 58 mmHg on room air. After bronchodilators, what is the most appropriate next intervention for respiratory acidosis?

Answer and explanation

Correct answer: B. Non-invasive positive pressure ventilation (BiPAP) with close arterial blood gas monitoring

  1. Step 1: Recognize acute hypercapnic respiratory failure secondary to severe COPD exacerbation with moderate respiratory acidosis (pH 7.25 - 7.35).
  2. Step 2: Non-invasive ventilation (NIV with bilevel positive airway pressure) reduces intubation rates, hospital stay, and in-hospital mortality in acute COPD exacerbations.
  3. Step 3: Uncontrolled 100% oxygen can blunt hypoxic drive and worsen hypercapnia through ventilation-perfusion mismatch and the Haldane effect.
Answer
Non-invasive positive pressure ventilation (NIV / BiPAP).
Why not the others: 'Immediate endotracheal intubation and mechanical ventilation' is invasive and indicated if NIV fails or if consciousness is severely impaired; 'High-flow 100% oxygen via non-rebreather reservoir mask' risks worsening CO2 retention and narcosis; 'Intravenous sodium bicarbonate 8.4% infusion' is contraindicated in respiratory acidosis as it increases dissolved CO2.

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