Patients with an altered mental status and a pulse ox reading of 90 percent should receive:

In the case of patients exhibiting altered mental status alongside a pulse oximetry reading of 90 percent, the priority in treatment is to provide supplemental oxygen. A pulse oxygen saturation of 90 percent indicates that the patient is experiencing hypoxemia, which can significantly impair oxygen delivery to vital organs and lead to further complications.

Administering oxygen helps to increase the amount of oxygen available in the bloodstream, improving tissue oxygenation and potentially reversing any neurological deficits resulting from low oxygen levels. This is crucial because the brain is highly sensitive to changes in oxygen supply; inadequate oxygen can lead to altered mental status and further deterioration.

In this context, while other options such as glucose or medications may play a role in specific medical conditions, they do not address the immediate respiratory issue indicated by the low oxygen saturation. Thus, providing oxygen is the most appropriate and effective intervention in this scenario to stabilize the patient and address their hypoxic condition.