What physiological change indicates respiratory alkalosis?

Respiratory alkalosis occurs when there is an increase in blood pH due to a decrease in carbon dioxide (CO2) levels. This decrease in CO2 is primarily caused by hyperventilation, which leads to the exhalation of more CO2 than the body produces. Since CO2 is an acid when dissolved in blood (it forms carbonic acid), a reduction in CO2 levels results in a reduction of acidity, thus increasing pH and creating an alkaline state.

In this context, decreased levels of CO2, or PCO2, are the key indicator of respiratory alkalosis. The body attempts to restore balance by various compensatory mechanisms, but the initial physiological change remains a decrease in CO2. Understanding this process is crucial to diagnosing and managing conditions that lead to respiratory alkalosis effectively.