What blood gas changes occur during hyperventilation?

During hyperventilation, the primary change observed is a decrease in carbon dioxide (CO2) levels in the blood. This occurs because hyperventilation involves rapid and deep breathing, which increases the rate of CO2 elimination from the body. As the CO2 levels drop, this leads to a state known as respiratory alkalosis, characterized by an increase in blood pH.

In terms of partial pressures, the decrease in CO2 (or hypercapnia) correlates with a decrease in arterial carbon dioxide tension (PaCO2). While oxygen levels (PaO2) can be mildly affected during hyperventilation, they typically remain stable or can even increase slightly as a result of wider alveolar expansion and improved gas exchange. However, significant changes in PaO2 are not a characteristic of hyperventilation, as oxygen saturation levels usually remain within the normal range unless other underlying conditions exist.

Thus, the correct answer highlights the significant decrease in CO2 levels while noting that PaO2 may increase; this aligns with physiological responses during hyperventilation.