After surgery, what is a common reason for a patient's oxygen saturation to drop?

A common reason for a patient's oxygen saturation to drop after surgery is hypoventilation. During the postoperative period, patients may experience decreased respiratory rate or depth due to the effects of anesthesia, pain, or sedation, which can lead to inadequate ventilation and impaired gas exchange. This reduced respiratory function can cause carbon dioxide retention and lower oxygen levels in the blood, ultimately resulting in decreased oxygen saturation.

In this context, it's important to understand that while dehydration, anxiety, and infection can all affect a patient’s overall well-being and recovery, they do not directly cause immediate respiratory compromise that would lead to a drop in oxygen saturation following a surgical procedure. Hypoventilation, on the other hand, directly impacts the breathing mechanics and is a critical factor to monitor in the PACU setting to ensure adequate oxygenation.