What should the nurse do first when obtaining a low pulse oximeter reading of 89% in a postoperative client?

In this situation, the most appropriate first action is to assess the client's respiratory status. A pulse oximeter reading of 89% indicates that the oxygen saturation in the client's blood is lower than the normal range, which typically falls between 95% and 100%.

Before taking further steps, it is crucial for the nurse to evaluate the patient's breathing pattern, effort, and any other signs of respiratory distress—such as cyanosis, use of accessory muscles, or abnormal lung sounds. By assessing the respiratory status, the nurse can gather vital information to determine the cause of the low pulse oximeter reading and decide on the next appropriate interventions.

While applying supplemental oxygen, repeating the test, or notifying the healthcare provider are important actions that may follow, they are contingent on understanding the patient's current respiratory condition first. This thorough assessment allows for a more tailored and effective response to the low oxygen saturation level.