What is a common indicator that a patient may require increased oxygen levels?

The correct indication that a patient may require increased oxygen levels is when SpO2 levels fall below 90%. This threshold is critical because an SpO2 reading below this level typically suggests that the oxygen saturation in the blood is inadequate for meeting the body's physiological needs. Normal arterial oxygen saturation is generally considered to be between 95% and 100%, so values below 90% can indicate hypoxemia, a condition where there is a deficiency of oxygen in the blood that could lead to serious health complications if not addressed.

Monitoring SpO2 levels is a standard practice in assessing a patient's respiratory status, and any significant drop may warrant immediate intervention, such as increasing supplemental oxygen, to ensure that the tissues and organs receive sufficient oxygen for optimal function.

In contrast, the other choices do not serve as reliable indicators for needing increased oxygen therapy. Increased appetite, a normal heart rate, and good color in lips and skin are generally not associated with low oxygen levels and do not provide accurate assessments regarding a patient's respiratory needs.