What action should the nurse take upon assessing a gastric aspirate pH of 4.5 in a client with a nasogastric tube?

The appropriate action in this scenario is to administer a dose of a prescribed antacid. A gastric aspirate pH of 4.5 indicates that the contents are acidic, which is consistent with normal gastric secretions. However, for clients who are at risk of complications from excess acidity—such as those with gastric ulcers or gastroesophageal reflux disease—administering an antacid can help neutralize the stomach acid and provide relief from symptoms associated with excessive acidity.

In this context, addressing the acidity is crucial for managing the patient’s comfort and preventing complications. The prescribed antacid would have been ordered specifically to alleviate symptoms or treat conditions related to gastric acid excess, making its administration appropriate following the pH assessment.

The other options, such as documenting the findings, while necessary in the nursing process, do not address the immediate need that the pH reading represents. Simply reassessing the pH in 4 hours would defer action without providing any therapeutic benefit in the interim. Instilling sterile water is also not appropriate, as it does not contribute to managing acidity and could further dilute gastric secretions, potentially affecting future pH readings.