Which of the following is a direct descriptor of hypercapnia?

• A. Elevated carbon dioxide in the blood
• B. Low carbon dioxide
• C. High oxygen
• D. Low nitrogen

Answer: (A)

Hypercapnia is defined by elevated carbon dioxide in the blood. CO2 is a waste product of metabolism that the lungs must remove through ventilation; when ventilation is inadequate or CO2 production exceeds removal, CO2 accumulates in the blood, raising the PaCO2. That direct descriptor—elevated carbon dioxide in the blood—captures what hypercapnia means. The other descriptions don’t fit: low CO2 describes hypocapnia, high oxygen refers to O2 levels rather than CO2, and low nitrogen isn’t a standard measure used to describe this condition.