A post-op patient has a sudden decrease in SpO2 levels to 88%. What should be the nurse's first action?

A. Increase the patient's IV fluid rate: Accelerating fluid administration does not address the primary issue of impaired gas exchange or pulmonary ventilation. In fact, excessive fluids could exacerbate low oxygen levels if the patient is developing pulmonary edema. This intervention is irrelevant to resolving acute desaturation. B. Reassure the patient and continue to monitor: A saturation level of 88% represents significant hypoxemia that requires immediate active intervention to prevent tissue hypoxia. Passive monitoring while a patient is in respiratory distress allows for further physiological decline. Clinical action must prioritize correcting the oxygen deficit over observation. C. Notify the anesthesiologist immediately: While communication with the surgical team is necessary, the nurse must first stabilize the patient's immediate physiological threat. Delaying life-saving oxygen therapy to place a phone call can lead to avoidable complications. Assessment and immediate intervention must precede notification in emergency situations. D. Administer supplemental oxygen via nasal cannula: Increasing the fraction of inspired oxygen is the priority action to correct acute hypoxemia. This intervention immediately supports cellular oxygenation and reduces the workload of the heart and lungs. It is the standard initial nursing response for postoperative respiratory depression.