How is hypercarbia characterized in terms of blood gas levels?

Hypercarbia, also known as hypercapnia, is characterized by elevated levels of carbon dioxide (CO2) in the bloodstream. This condition arises when there is an imbalance in the body's ability to eliminate carbon dioxide, which could be due to various respiratory issues, such as chronic obstructive pulmonary disease (COPD), respiratory failure, or hypoventilation.

When CO2 accumulates in the blood, it increases the partial pressure of carbon dioxide, which can lead to respiratory acidosis and can affect the body's pH balance. Symptoms of hypercarbia may include headache, confusion, drowsiness, and in severe cases, can lead to loss of consciousness or respiratory distress.

In contrast, the other options refer to conditions that are not associated with hypercarbia. Low oxygen levels in the blood indicate hypoxemia, while low carbon dioxide levels would define a state of hypocapnia, which occurs in hyperventilation. Elevated oxygen levels do not relate to hypercarbia either, as oxygen levels are independent of CO2 levels and primarily reflect the adequacy of oxygenation. Thus, elevated carbon dioxide levels in the blood is the defining characteristic of hypercarbia.