What symptom might indicate high carbon dioxide levels in a client?

High carbon dioxide levels, a condition known as hypercapnia, can lead to various physiological responses. Flushed skin can occur as a result of increased blood flow and dilation of blood vessels in response to a rising carbon dioxide concentration in the blood. When the body experiences an excess of carbon dioxide, it triggers a series of compensatory mechanisms to help restore balance, and the resultant vasodilation can manifest as flushed skin.

Increased carbon dioxide levels may also lead to other symptoms like headache, confusion, and lethargy; however, among the given options, flushed skin is the most likely indicator directly associated with high carbon dioxide levels. While cyanosis can indicate hypoxemia (low oxygen), and anxiety might be a response rather than a direct indicator of elevated carbon dioxide, they are not the most characteristic symptoms in this context. Increased appetite is also not linked to high carbon dioxide levels, making flushed skin the most relevant symptom here.