If an excessive amount of oxygen is given to a COPD patient, what respiratory changes may occur?

• A. Respiratory alkalosis
• B. Hypercapnia and respiratory acidosis
• C. Hypoxemia
• D. Metabolic acidosis

Answer: (B)

In COPD, giving too much oxygen can blunt the drive to breathe because the body often relies on low oxygen levels to stimulate ventilation rather than CO2. When you flood the system with oxygen, ventilation may decrease, allowing carbon dioxide to build up. The higher CO2 level (hypercapnia) shifts the blood’s pH toward acidity, producing respiratory acidosis. In chronic COPD, the kidneys may compensate by retaining bicarbonate, which can blunt the pH change, but the primary issue remains the rise in CO2 from reduced ventilation. Respiratory alkalosis would come from excessive breathing, not from oxygen suppression, so that isn’t the expected outcome here. Hypoxemia would be improved, not caused, by excess oxygen, and metabolic acidosis isn’t a direct result of oxygen therapy in this context.