Which of the following conditions indicates respiratory alkalosis?

• A. Increased carbon dioxide levels
• B. Decreased oxygen levels
• C. Decreased carbon dioxide levels
• D. Increased oxygen saturation

Answer: (C)

Respiratory alkalosis is characterized by a decrease in carbon dioxide levels in the blood, leading to an increase in blood pH. When the body hyperventilates, more carbon dioxide is expelled from the lungs than is produced by the body’s metabolism. This reduction in carbon dioxide causes a decrease in hydrogen ions in the blood, which is what elevates the pH and results in a more alkaline state.

The first choice, which indicates increased carbon dioxide levels, is associated with respiratory acidosis rather than alkalosis. The second choice, concerning decreased oxygen levels, does not directly relate to the acid-base status in this context; while it might accompany respiratory distress, it isn't a primary indicator of respiratory alkalosis. The fourth choice, increased oxygen saturation, reflects improved oxygen delivery but does not have a direct correlation with carbon dioxide levels or the acid-base balance. Thus, the condition that indicates respiratory alkalosis is indeed marked by decreased carbon dioxide levels, aligning with the understanding of the physiological processes involved.