Emergency Medicine Drugs Practice Test 2026 – Comprehensive Exam Prep

In COPD, some patients rely on hypoxic drive to breathe—their brain responds more to low oxygen than to high CO2. Giving too much oxygen can blunt that drive, leading to reduced ventilation and a rise in CO2 (hypercapnia), which can cause respiratory acidosis. Because of this, oxygen therapy is given carefully and titrated to modest saturation targets (often around 88–92%), with close monitoring to balance improving oxygenation against the risk of CO2 retention.

It isn’t that oxygen always worsens COPD or that it has no effect—the risk applies to those who depend on low oxygen levels to drive respiration, not to all patients. Oxygen should not be avoided in all COPD; it’s used when there is true hypoxemia, but delivered in a controlled way to minimize respiratory drive depression.