Why is the SpO2 target lower for COPD patients?

• A. Because they have chronic CO2 retention where high O2 can depress ventilatory drive
• B. To prevent oxygen toxicity
• C. Because oxygen therapy is ineffective in COPD
• D. To save oxygen usage

Answer: (B)

In COPD with chronic CO2 retention, the body's drive to breathe is more influenced by low oxygen levels than by carbon dioxide. Giving too much oxygen can remove the hypoxic stimulus that helps stimulate respiration, leading to hypoventilation and a rise in CO2 (hypercapnia). To prevent this dangerous buildup while still keeping oxygenation adequate, clinicians target a lower SpO2—typically around 88–92%. This balance helps maintain sufficient oxygen delivery without suppressing the patient’s spontaneous ventilation.

Context helps: COPD patients often have damaged airways and gas exchange, so keeping oxygen within that range reduces the risk of CO2 retention while avoiding significant hypoxemia. While oxygen toxicity is a consideration with very high FiO2, the primary reason for a lower SpO2 target in COPD is to avoid depressing respiratory drive and CO2 retention, not to prevent oxygen toxicity.