Which condition is characterized by a decreased arterial CO2 tension?

The condition characterized by a decreased arterial CO2 tension is indeed alveolar hyperventilation. This occurs when there is an increase in the rate and/or depth of breathing, leading to excessive expulsion of carbon dioxide (CO2) from the body. When CO2 levels drop in the bloodstream, this results in a decreased arterial CO2 tension, also known as hypocapnia.

Alveolar hyperventilation can be triggered by various factors, such as anxiety, pain, or certain medical conditions, and it directly affects the gas exchange in the lungs. In contrast, conditions like asthma, chronic bronchitis, and pneumonia typically involve impaired gas exchange and can lead to elevated CO2 levels due to difficulty in airflow and inadequate removal of CO2 from the bloodstream.

Understanding the relationship between ventilation and arterial CO2 levels is crucial when assessing respiratory status in patients, particularly in differentiating between various respiratory conditions.