An arterial CO2 tension of less than 35 mm Hg indicates what condition?

• A. Alveolar hypoventilation
• B. Normal ventilation
• C. Alveolar hyperventilation
• D. Acidosis

Answer: (C)

An arterial CO2 tension of less than 35 mm Hg indicates a condition known as alveolar hyperventilation. When the CO2 levels in the blood drop below this threshold, it suggests that the lungs are expelling carbon dioxide at a rate faster than the body is producing it. This increased rate of ventilation leads to a decrease in carbon dioxide tension, which can result from factors such as anxiety, high levels of physical activity, or certain medical conditions affecting respiratory drive.

In conditions where there is alveolar hyperventilation, the body is effectively reducing the concentration of carbon dioxide, which can lead to respiratory alkalosis as a result. Therefore, recognizing hyperventilation based on CO2 tension is crucial for understanding the patient's respiratory status and guiding appropriate interventions.